Giant dipole resonance parameters with uncertainties from photonuclear cross sections
NASA Astrophysics Data System (ADS)
Plujko, V. A.; Capote, R.; Gorbachenko, O. M.
2011-09-01
Updated values and corresponding uncertainties of isovector giant dipole resonance (IVGDR or GDR) model parameters are presented that are obtained by the least-squares fitting of theoretical photoabsorption cross sections to experimental data. The theoretical photoabsorption cross section is taken as a sum of the components corresponding to excitation of the GDR and quasideuteron contribution to the experimental photoabsorption cross section. The present compilation covers experimental data as of January 2010.
Matsumoto, E.; Nakayama, S.; Hayami, R.; Fushimi, K.; Kawasuso, H.; Yasuda, K.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Fujiwara, M.; Yosoi, M.; Nakanishi, K.; Kawase, K.; Hashimoto, H.; Oota, T.; Sagara, K.; Kudoh, T.; Asaji, S.; Ishida, T.; Tanaka, M.
2007-02-26
We investigated the analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) of 4He by using the 4He(7Li,7Be) reaction at an incident energy of 455 MeV and at forward scattering angles. The {delta}S=0 and {delta}S=1 spectra for 4He were obtained by measuring the 0.43-MeV 7Be {gamma}-ray in coincidence with the scattered 7Be. From the {delta}S=0 and {delta}S=1 spectra thus obtained, the strength distributions of the GDR and SDR in 4He can be derived and the results are compared with the previous data.
Pygmy dipole resonance and dipole polarizability in {sup 90}Zr
Iwamoto, C.; Tamii, A.; Shima, T.; Hashimoto, T.; Suzuki, T.; Fujita, H.; Hatanaka, K.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Okamoto, A.; Kondo, T.; Nakada, H.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Shimbara, Y.; Nagashima, M.; Sakuda, M.; Mori, T.; and others
2014-05-02
Electric dipole (E1) reduced transition probability B(E1) of {sup 90}Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability α{sub D} which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.
Pygmy dipole resonance and dipole polarizability in 90Zr
NASA Astrophysics Data System (ADS)
Iwamoto, C.; Tamii, A.; Utsunomiya, H.; Akimune, H.; Nakada, H.; Shima, T.; Hashimoto, T.; Yamagata, T.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Suzuki, T.; Fujita, H.; Shimbara, Y.; Nagashima, M.; Sakuda, M.; Mori, T.; Izumi, T.; Okamoto, A.; Kondo, T.; Lui, T.-W.; Bilgier, B.; Kozer, H. C.; Hatanaka, K.
2014-05-01
Electric dipole (E1) reduced transition probability B(E1) of 90Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability αD which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.
Dipole-quadrupole Förster resonance in cesium Rydberg gas
NASA Astrophysics Data System (ADS)
Maineult, Wilfried; Pelle, Bruno; Faoro, Riccardo; Arimondo, Ennio; Pillet, Pierre; Cheinet, Patrick
2016-11-01
The resonant energy transfer between two close particles, also known as Förster resonance in atomic or biological systems, is usually associated with dipole-dipole interaction. In Rydberg atoms, it is a widely used tool to enhance the interactions between particles. Here, we observe a resonant energy transfer between Rydberg atoms that cannot be attributed to a dipole-dipole interaction, owing to selection rules, and comes instead from an efficient dipole-quadrupole process. We compare the measured probability transfer with a theoretical model including quadrupolar terms and find very good agreement with our measurement. Further studies of those multipolar resonances should probe their dependences on various parameters (quantum numbers, relative orientation of the atoms), and may find some applications in quantum procedures where dipole-dipole resonance cannot be used, for instance where the states of interest have a difference in angular momentum of two.
Ricz, S.; Ricsoka, T.; Holste, K.; Borovik, A. Jr.; Bernhardt, D.; Schippers, S.; Mueller, A.; Koever, A.; Varga, D.
2010-04-15
The angular distribution of the Kr 4p photoelectrons was investigated in the photon energy range of the (3d){sup -1{yields}}np resonant excitations. The experimental dipole ({beta}) and nondipole ({gamma} and {delta}) anisotropy parameters were determined for the spin-orbit components of the Kr 4p shell. A simple theoretical model was developed for the description of the photoionization and excitation processes. An interference effect was observed between the direct photoionization and the resonant excitation participator Auger decay processes in the photon energy dependence of the experimental anisotropy parameters.
Description of resonant processes in the dipole moment interaction
NASA Astrophysics Data System (ADS)
Vargas Morales, M.; Torres Rodríguez, M. A.; De Los Santos García, S. I.; García Guzman, A.; Martínez Niconoff, G.
2016-09-01
We analyze the resonant interaction between cumulus of nano-particles distributed on a two-dimensional array controlling the polarization states on the illumination, this allows controlling the dipole moment induced in a tunable-way obtaining an analytic expression for the refractive index. The resonant effects depend on the parameters that characterize the spatial distribution of the particle arrangement. We present two cases, firstly the interaction is described using a linear polarization on a linear particle array, and secondly it is obtained using circular polarization inducing resonant interaction between ring-particle kind structures. The refractive index associated to both configurations is implemented in the Fresnel equations for the study of the reflectivity and transmittance of optical fields. As a main result of the analysis is that we can to identify and control the parameters required for the synthesis of metamaterials. Computer simulations are presented.
New Insight into the Pygmy Dipole Resonance in Stable Nuclei
Neumann-Cosel, P. von
2008-11-11
Two examples of recent work on the structure of low-energy electric dipole modes are presented. The first part discusses the systematics of the pygmy dipole resonance (PDR) in stable tin isotopes deduced from high-resolution ({gamma},{gamma}') experiments. These help to distinguish between microscopic QRPA calculations based on either a relativistic or a nonrelativistic mean-field description, predicting significantly different properties of the PDR. The second part presents attempts to unravel the structure of dipoles modes at energies below the giant dipole resonance (GDR) in {sup 208}Pb with a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg.
Structure of the pygmy dipole resonance in 124Sn
NASA Astrophysics Data System (ADS)
Endres, J.; Savran, D.; Butler, P. A.; Harakeh, M. N.; Harissopulos, S.; Herzberg, R.-D.; Krücken, R.; Lagoyannis, A.; Litvinova, E.; Pietralla, N.; Ponomarev, V. Yu.; Popescu, L.; Ring, P.; Scheck, M.; Schlüter, F.; Sonnabend, K.; Stoica, V. I.; Wörtche, H. J.; Zilges, A.
2012-06-01
Background: In atomic nuclei, a concentration of electric dipole strength around the particle threshold, commonly denoted as pygmy dipole resonance, may have a significant impact on nuclear structure properties and astrophysical scenarios. A clear identification of these states and the structure of this resonance is still under discussion.Purpose: We present an experimental and theoretical study of the isospin character of the pygmy dipole resonance and investigation of a splitting of the electric dipole strength previously observed in experiments on N=82 nuclei.Method: The pygmy dipole resonance has been studied in the semi-magic Z=50 nucleus 124Sn by means of the (α,α'γ) coincidence method at Eα=136MeV using the Big-Bite Spectrometer at the Kernfysisch Versneller Instituut in Groningen, The Netherlands.Results: A splitting of the low-energy part of the electric dipole strength was identified in 124Sn by comparing the differential cross sections measured in (α,α'γ) to results stemming from (γ,γ') photon-scattering experiments. While an energetically lower-lying group of states is observed in both kinds of experiments, a higher-lying group of states is only excited in the (γ,γ') reaction. In addition, theoretical calculations using the self-consistent relativistic quasiparticle time-blocking approximation and the quasiparticle-phonon model have been performed. Both calculations show a qualitative agreement with the experimental data and predict a low-lying isoscalar component that is dominated by neutron-skin oscillations as expected for the pygmy dipole resonance. Furthermore, the states at higher energies show a pronounced isovector component and a different radial dependence of the corresponding transition densities as expected for the tail of the giant dipole resonance.Conclusions: An experimental signature of the neutron-skin oscillation of the pygmy dipole resonance has been corroborated. The combination of the presented reactions might make it
Plasmon-Induced Resonant Energy Transfer: a coherent dipole-dipole coupling mechanism
NASA Astrophysics Data System (ADS)
Bristow, Alan D.; Cushing, Scott K.; Li, Jiangtian; Wu, Nianqiang
Metal-insulator-semiconductor core-shell nanoparticles have been used to demonstrate a dipole-dipole coupling mechanism that is entirely dependent on the dephasing time of the localized plasmonic resonance. Consequently, the short-time scale of the plasmons leads to broad energy uncertainty that allows for excitation of charge carriers in the semiconductor via stimulation of photons with energies below the energy band gap. In addition, this coherent energy transfer process overcomes interfacial losses often associated with direct charge transfer. This work explores the efficiency of the energy transfer process, the dipole-dipole coupling strength with dipole separation, shell thickness and plasmonic resonance overlap. We demonstrate limits where the coherent nature of the coupling is switched off and charge transfer processes can dominate. Experiments are performed using transient absorption spectroscopy. Results are compared to calculations using a quantum master equation. These nanostructures show strong potential for improving solar light-harvesting for power and fuel generation.
Beam induced electron cloud resonances in dipole magnetic fields
NASA Astrophysics Data System (ADS)
Calvey, J. R.; Hartung, W.; Makita, J.; Venturini, M.
2016-07-01
The buildup of low energy electrons in an accelerator, known as electron cloud, can be severely detrimental to machine performance. Under certain beam conditions, the beam can become resonant with the cloud dynamics, accelerating the buildup of electrons. This paper will examine two such effects: multipacting resonances, in which the cloud development time is resonant with the bunch spacing, and cyclotron resonances, in which the cyclotron period of electrons in a magnetic field is a multiple of bunch spacing. Both resonances have been studied directly in dipole fields using retarding field analyzers installed in the Cornell Electron Storage Ring. These measurements are supported by both analytical models and computer simulations.
Influence of medium chirality on electric dipole-dipole resonance energy transfer
NASA Astrophysics Data System (ADS)
Rodriguez, Justo J.; Salam, A.
2010-09-01
Electric dipole-dipole resonance energy transfer taking place between two chromophores in an absorptive and dispersive chiral medium is studied. Quantized electromagnetic field operators in this environment are first obtained from the time-harmonic Maxwell equations and the Drude-Born-Fedorov equations. Second-order time-dependent perturbation theory and the Fermi Golden rule are used to calculate the transfer rate. A complicated dependence on the permittivity, permeability and chirality admittance of the medium is found. In the near-zone, the rate is amplified in a medium with negligible absorption comprised of one enantiomer relative to that in a racemic mixture.
Investigation of pygmy dipole resonance in 154Sm
NASA Astrophysics Data System (ADS)
Quliyev, Huseynqulu; Zenginerler, Zemine; Guliyev, Ekber; Kuliev, Ali Akbar
2017-02-01
In this paper, an investigation of the pygmy dipole resonance (PDR) in 154Sm nucleus has been performed using quasi particle random-phase approximation (QRPA). Analysis of the numerical results indicates that both ΔK=1 and ΔK=0 branches plays significant role in formation of PDR.
Huygens’ Metasurfaces Enabled by Magnetic Dipole Resonance Tuning in Split Dielectric Nanoresonators
Liu, Sheng; Vaskin, Aleksandr; Campione, Salvatore; ...
2017-06-07
Dielectric metasurfaces that exploit the different Mie resonances of nanoscale dielectric resonators are a powerful platform for manipulating electromagnetic fields and can provide novel optical behavior. Here in this work, we experimentally demonstrate independent tuning of the magnetic dipole resonances relative to the electric dipole resonances of split dielectric resonators (SDRs). By increasing the split dimension, we observe a blue shift of the magnetic dipole resonance toward the electric dipole resonance. Therefore, SDRs provide the ability to directly control the interaction between the two dipole resonances within the same resonator. For example, we achieve the first Kerker condition by spectrallymore » overlapping the electric and magnetic dipole resonances and observe significantly suppressed backward scattering. Moreover, we show that a single SDR can be used as an optical nanoantenna that provides strong unidirectional emission from an electric dipole source.« less
Investigating the Pygmy Dipole Resonance Using β Decay
NASA Astrophysics Data System (ADS)
Scheck, M.; Mishev, S.; Ponomarev, V. Yu.; Chapman, R.; Gaffney, L. P.; Gregor, E. T.; Pietralla, N.; Spagnoletti, P.; Savran, D.; Simpson, G. S.
2016-04-01
In this contribution it is explored whether γ -ray spectroscopy following β decay with high Q values from mother nuclei with low ground-state spin can be exploited as a probe for the pygmy dipole resonance. The suitability of this approach is demonstrated by a comparison between data from photon scattering, 136Xe (γ ,γ') , and 136I [J0π=(1-)]→136Xe* β -decay data. It is demonstrated that β decay populates 1- levels associated with the pygmy dipole resonance, but only a fraction of those. The complementary insight into the wave functions probed by β decay is elucidated by calculations within the quasiparticle phonon model. It is demonstrated that β decay dominantly populates complex configurations, which are only weakly excited in inelastic scattering experiments.
Positronium-dipole induced resonances in e +-H and e +-alkali systems
NASA Astrophysics Data System (ADS)
Umair, M.; Jonsell, S.
2017-02-01
We derive general universal scaling relations governing resonances induced by the dipole moment of excited positronium interacting with atomic ions. A single non-universal parameter, which contains all the system-dependent information, is defined. Our results are compared to numerical calculations, using complex scaling, for S, P, and D-wave resonances below the positronium n = 2 threshold in the {{e}}+-(H, Li, Na, K) systems. The energy and width ratios of the successive resonances are found to agree well with the analytically derived scaling law.
Soft dipole resonance and halo structure of 11Li
NASA Astrophysics Data System (ADS)
Kanungo, Rituparna
2016-03-01
The discovery of the nuclear halo in rare isotopes has ushered a new era in nuclear science breaking the boundaries of conventional concepts. The halo properties elucidate new features that till date remain a challenge to decipher from fundamental principles. Our knowledge on the halo is still gradually unfolding and reaching new levels of precision as efforts continue towards new experimental developments. In recent times, low-energy reactions in inverse kinematics have become possible providing a wealth of new structure information. In this presentation we will introduce a new reaction spectroscopy facility, IRIS, with a novel thin windowless solid H2/D2 target for studying transfer and inelastic scattering reactions of rare isotopes with very low yields. It was postulated that the loosely bound halo of two neutrons may lead to a core-halo oscillation resulting in dipole resonance(s) at very low excitation energy, called soft dipole resonance. Despite decades of search for this new phenomenon using various techniques, such as, no firm conclusion was reached. The presentation will discuss new results from IRIS that shows evidence of a soft dipole resonance state and further unveils its isoscalar character. New results of neutron transfer from 11Li will be presented showing resonance state(s) in the neutron unbound 10Li subsystem hence facilitating a description of the wavefunction of 11Li. NSERC, Canada Foundation for Innovation, Nova Scotia Research and Innovation Trust, grant-in-aid program of the Japanese government under Contract No. 23224008, US DOE Contract No. DE-AC52-07NA27344.
Investigation of the isoscalar giant dipole resonance in Pb-208
NASA Astrophysics Data System (ADS)
Davis, Benny Fay
1997-11-01
An investigation of the Isoscalar Giant Dipole Resonance in 208Pb is described in the present dissertation. The 208Pb(/alpha,/alpha/sp/prime) reaction was employed using a high resolution spectrometer (K600) and a 200 MeV α beam at the Indiana University Cyclotron Facility in Bloomington, Indiana. The K600 spectrometer yielded measurements of particle identification (ΔE vs. E), energy/momentum, timing with the cyclotron frequency and slope of the particle track. This latter characteristic permitted us to perform ray-tracing back through the spectrometer to the Lead target and hence, learn the scattering angle associated with each event. The 2o acceptance of the spectrometer and software cuts allowed us to measure angular distributions around 0o. Based on the present study, we have identified a previously known but unresolved Isoscalar Giant Dipole Resonance (ISGDR). This ISGDR remained unresolved for years due to the fact that a competing resonance, namely the High Energy Octupole Resonance (HEOR), sat at roughly the same energy in all of the finite angle spectra taken previously. Our method solved the problem by utilizing the fact that the only differences in angular distributions of a dipole (L = 1) and an octupole (L = 3) resonance occur around a scattering angle of 0o. In the 0o to 2o angular range, the angular distribution of the HEOR is nearly flat. Therefore, the HEOR's contribution can be removed using a 'difference-of- spectra' technique where a 0o to 1o angular cut is subtracted from a 1o to 2o angular cut (normalized for solid angle differences) removing any effect in the spectra possessing a flat angular distribution, namely the HEOR and most of the experimental background. From these measurements, we have obtained the first conclusive evidence for the ISGDR and have extracted the value of KA, the incompressibility of nuclear matter.
Direct neutron decay of the isoscalar giant dipole resonance
Hunyadi, M. Berg, A. M. van den; Davids, B.; Harakeh, M. N.; Huu, M. A. de; Woertche, H. J.; Csatlos, M.; Gulyas, J.; Krasznahorkay, A.; Sohler, D.; Garg, U.; Fujiwara, M.; Blasi, N.
2007-08-15
The direct and statistical neutron decay of the isoscalar giant dipole resonance has been studied in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb using the ({alpha}, {alpha}' n) reaction at a bombarding energy of 200 MeV. The spectra of fast decay neutrons populating valence hole states of the Z, N - 1 nuclei were analyzed, and estimates for the branching ratios were determined. The observation of the nucleon-direct-decay channels helped to select giant-resonance strengths and suppress the underlying background and continuum, which led to an indication of the existence of a new mode with L 2 character, presumably the overtone of the isoscalar giant quadrupole resonance.
Comment on "Thermal shape fluctuation model study of the giant dipole resonance in 152Gd"
NASA Astrophysics Data System (ADS)
Chakrabarty, D. R.; Datar, V. M.
2016-10-01
A recent paper [A. K. Rhine Kumar and P. Arumugam, Phys. Rev. C 92, 044314 (2015), 10.1103/PhysRevC.92.044314] presented calculations of the giant dipole resonance width and γ -ray absorption cross sections for 152Gd at various temperatures and angular momenta and compared these with the experimental data. In the comparison of the cross sections, the authors used the linearized representations of the experimental spectra which actually represent the absorption cross sections divided by the γ -ray energy. In this Comment we make the comparison with the appropriate absorption cross sections derived from the data. The comparison shows a reasonable agreement if the higher value of the dipole-dipole interaction parameter, mentioned in the paper, is used in the calculation.
The Giant Dipole Resonance at Very High Temperatures
NASA Astrophysics Data System (ADS)
Suomijärvi, T.; Le Faou, J. H.; Blumenfeld, Y.; Piattelli, P.; Agodi, C.; Alamanos, N.; Alba, R.; Auger, F.; Bellia, G.; Chomaz, Ph.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Gaardhøje, J. J.; Garron, J. P.; Gillibert, A.; Lamehi-Rachti, M.; Liguori-Neto, R.; Loukachine, K.; Maiolino, C.; Migneco, E.; Montironi, S.; Russo, G.; Roynette, J. C.; Santonocito, D.; Sapienza, P.; Scarpaci, J. A.; Smerzi, A.
1995-02-01
Gamma-rays emitted from hot nuclei of mass around 115 and excitation energies above 300 MeV, formed in the 36Ar + 90Zr at 27 MeV/u, 36Ar + 94Zr at 32 MeV/u and 36Ar + 98Mo at 37 MeV/u, have been measured with the MEDEA multidetector in coincidence with evaporation residues. The γ-ray yield from the decay of the Giant Dipole Resonance is independent of excitation energy and of bombarding energy.
Giant dipole resonance in 201Tl at low temperature
NASA Astrophysics Data System (ADS)
Dang, N. Dinh; Hung, N. Quang
2012-10-01
The thermal pairing gap obtained by embedding the exact solutions of the pairing problem into the canonical ensemble is employed to calculate the width and strength function of the giant dipole resonance (GDR) within the phonon damping model. The results of calculations describe reasonably well the data for the GDR width as well as the GDR linearized strength function, recently obtained for 201Tl in the temperature region between 0.8 and 1.2 MeV, for which other approaches that neglect the effect of nonvanishing thermal pairing fail to describe.
Excitation-energy dependence of the giant dipole resonance width
NASA Astrophysics Data System (ADS)
Enders, G.; Berg, F. D.; Hagel, K.; Kühn, W.; Metag, V.; Novotny, R.; Pfeiffer, M.; Schwalb, O.; Charity, R. J.; Gobbi, A.; Freifelder, R.; Henning, W.; Hildenbrand, K. D.; Holzmann, R.; Mayer, R. S.; Simon, R. S.; Wessels, J. P.; Casini, G.; Olmi, A.; Stefanini, A. A.
1992-07-01
High-energy γ rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of 136Xe+48Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width Γ is studied as a function of the fragment excitation energy E*. A saturation at about Γ=10 MeV is observed for E*/A>=1.0 MeV/nucleon.
Dipole-dipole resonance line shapes in a cold Rydberg gas
NASA Astrophysics Data System (ADS)
Richards, B. G.; Jones, R. R.
2016-04-01
We have explored the dipole-dipole mediated, resonant energy transfer reaction, 32 p3 /2+32 p3 /2→32 s +33 s , in an ensemble of cold 85Rb Rydberg atoms. Stark tuning is employed to measure the population transfer probability as a function of the total electronic energy difference between the initial and final atom-pair states over a range of Rydberg densities, 2 ×108≤ρ ≤3 ×109 cm-3. The observed line shapes provide information on the role of beyond nearest-neighbor interactions, the range of Rydberg atom separations, and the electric field inhomogeneity in the sample. The widths of the resonance line shapes increase approximately linearly with the Rydberg density and are only a factor of 2 larger than expected for two-body, nearest-neighbor interactions alone. These results are in agreement with the prediction [B. Sun and F. Robicheaux, Phys. Rev. A 78, 040701(R) (2008), 10.1103/PhysRevA.78.040701] that beyond nearest-neighbor exchange interactions should not influence the population transfer process to the degree once thought. At low densities, Gaussian rather than Lorentzian line shapes are observed due to electric field inhomogeneities, allowing us to set an upper limit for the field variation across the Rydberg sample. At higher densities, non-Lorentzian, cusplike line shapes characterized by sharp central peaks and broad wings reflect the random distribution of interatomic distances within the magneto-optical trap (MOT). These line shapes are well reproduced by an analytic expression derived from a nearest-neighbor interaction model and may serve as a useful fingerprint for characterizing the position correlation function for atoms within the MOT.
Integral characteristic parameters of the giant {ital M}1 resonance
Bastrukov, S.I.; Molodtsova, I.V.; Shilov, V.M.
1995-08-01
The dipole magnetization of a heavy spherical nucleus is studied with macroscopic standpoint. The semiclassical model under consideration focuses on the giant {ital M}1 resonance as a result of long wavelength oscillations of the collective magnetization current induced in the surface massive layer of finite depth. The macroscopic picture of the excited collective flow is found to be like that for the torsional elastic vibrations of the peripheral layer against the central spherical region inert with respect to external perturbation. The emphasis is placed on calculation of scaling behavior of integral characteristic parameters of magnetic dipole resonance.
Evaluation of the Chromium Resonance Parameters Including Resonance Parameter Covariance
Leal, Luiz C; Derrien, Herve; Guber, Klaus H; Arbanas, Goran; Wiarda, Dorothea
2011-01-01
The intent of this work is to report the results and describe the procedures utilized to evaluate the chromium isotopes' cross sections, i.e., (50)Cr, (52)Cr, (53)Cr, and (54)Cr, for criticality safety applications. The evaluations were done in the resolved resonance region using the reduced Reich-Moore R-matrix formalism. The novel aspect of this evaluation is the inclusion of new transmission and capture cross-section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) for energies below 100 keV and the extension of the (53)Cr energy region. The resonance analysis was performed with the multilevel R-matrix code, SAMMY, which utilizes the generalized least-squares technique based on the Bayes' theory. Complete sets of resonance parameters and resonance parameter covariance matrices (RPCMs) were obtained for each of the chromium isotopes from the SAMMY analysis of the experimental database.
NASA Astrophysics Data System (ADS)
Wang, K.; Ma, Y. G.; Zhang, G. Q.; Cao, X. G.; He, W. B.; Shen, W. Q.
2017-01-01
Proton capture reaction is an important process concerning the astrophysical origin of the elements. In present work, we focus on giant dipole resonance (GDR) in proton capture reactions, such as 11B(p ,γ )12C , 27Al(p ,γ )28Si , 39K(p ,γ )40Ca , and 67Co(p ,γ )68Ni in a framework of an extended quantum molecular dynamics model. The systematic properties of GDR parameters including the peak energy, the strength, and full width at half maximum (FWHM) have been studied. The dependence of FWHM on temperature has also been discussed. Some comparisons with experimental data have been presented.
On field line resonances of hydromagnetic Alfven waves in dipole magnetic field
Chen, Liu; Cowley, S.C.
1989-07-01
Using the dipole magnetic field model, we have developed the theory of field line resonances of hydromagnetic Alfven waves in general magnetic field geometries. In this model, the Alfven speed thus varies both perpendicular and parallel to the magnetic field. Specifically, it is found that field line resonances do persist in the dipole model. The corresponding singular solutions near the resonant field lines as well as the natural definition of standing shear Alfven eigenfunctions have also been systematically derived. 11 refs.
Evolution of the giant dipole resonance properties with excitation energy
NASA Astrophysics Data System (ADS)
Santonocito, D.; Blumenfeld, Y.
2006-10-01
The studies of the evolution of the hot Giant Dipole Resonance (GDR) properties as a function of excitation energy are reviewed. The discussion will mainly focus on the A ˜ 100-120 mass region where a large amount of data concerning the width and the strength evolution with excitation energy are available. Models proposed to interpret the main features and trends of the experimental results will be presented and compared to the available data in order to extract a coherent scenario on the limits of the development of the collective motion in nuclei at high excitation energy. Experimental results on the GDR built in hot nuclei in the mass region A ˜ 60-70 will be also shown, allowing to investigate the mass dependence of the main GDR features. The comparison between limiting excitation energies for the collective motion and critical excitation energies extracted from caloric curve studies will suggest a possible link between the disappearance of collective motion and the liquid-gas phase transition.
Loading Dynamics and Characteristics of a Far Off-Resonance Optical Dipole Trap
NASA Astrophysics Data System (ADS)
Martinez, Y. N.; Mickelson, P. G.; Nagel, S. B.; Killian, T. C.
2007-06-01
We implement an optical dipole trap in a crossed beam configuration for experiments with ultracold strontium. Strontium atoms cooled to nearly 1 μK are loaded into the optical dipole trap from a magneto-optical trap operating on the 689 nm intercombination line. Loading dynamics and characteristics of the far off-resonance dipole trap are explored as part of our group's study of ultracold collisions in strontium.
Loading Dynamics and Characteristics of a Far Off-Resonance Optical Dipole Trap
NASA Astrophysics Data System (ADS)
Mickelson, P. G.; Martinez, Y. N.; Nagel, S. B.; Traverso, A. J.; Killian, T. C.
2007-10-01
We implement an optical dipole trap in a crossed beam configuration for experiments with ultracold strontium. Strontium atoms cooled to nearly 1 μK are loaded into the optical dipole trap from a magneto-optical trap operating on the 689 nm intercombination line. Loading dynamics and characteristics of the far off-resonance dipole trap are explored as part of our group's study of ultracold collisions in strontium.
Dipole Excitation of Soft and Giant Resonances in 132Sn and neighboring unstable nuclei
NASA Astrophysics Data System (ADS)
Boretzky, Konstanze
2006-04-01
The evolution of dipole-strength distributions above the one-neutron threshold was investigated for exotic neutron-rich nuclei in a series of experiments using the electromagnetic projectile excitation at beam energies around 500 MeV/u. For halo nuclei, the large observed dipole strength (shown here for 11Be) is explained within the direct-breakup model to be of non-collective character. For neutron-rich oxygen isotopes, the origin of the observed low-lying strength is concluded to be due to single-particle transitions on theoretical grounds. The dipole strength spectra for 130,132Sn exhibit resonance-like structures observed at energies around 10 MeV exhausting a few percent of the Thomas-Reiche-Kuhn (TRK) sum rule, separated clearly from the dominant Giant Dipole Resonance (GDR). The data agree with predictions for a new dipole mode related to the oscillation of excess neutrons versus the core nucleons ("pygmy resonance").
NASA Astrophysics Data System (ADS)
Faraji, Elham; Baghshahi, Hamid Reza; Tavassoly, Mohammad Kazem
2017-02-01
In this paper, the non-resonant interaction of two two-level atoms with two quantized cavity fields is studied by considering the dipole-dipole interaction between the two atoms. The correlation between the fields has been taken into account and the parametric down conversion is considered. Under certain initial conditions which is determined for the atoms and the fields, the analytical solution for the time-dependent Schrödinger equation is obtained. Employing this solution, we are able to discuss about some physical properties such as atomic population inversion and entanglement between various subsystems, i.e. “atoms-fields” and “atom-atom” by using respectively von Neumann entropy and negativity. It is deduced from the numerical results that, the mentioned quantities can be controlled by the atomic dipole-dipole interaction and detuning parameter, appropriately. The results show that the degree of entanglement between the two atoms is increased due to the presence of dipole-dipole coupling of the atoms at the beginning of atom-field interaction. Furthermore, it is found that, in the non-resonance condition, the so-called entanglement sudden death occurs in the presence of dipole-dipole interaction.
Magnetic dipole strength in 128Xe and 134Xe in the spin-flip resonance region
NASA Astrophysics Data System (ADS)
Massarczyk, R.; Rusev, G.; Schwengner, R.; Dönau, F.; Bhatia, C.; Gooden, M. Â. E.; Kelley, J. Â. H.; Tonchev, A. Â. P.; Tornow, W.
2014-11-01
The magnetic dipole strength in the energy region of the spin-flip resonance is investigated in 128Xe and 134Xe using quasimonoenergetic and linearly polarized γ -ray beams at the High-Intensity γ -Ray Source facility in Durham, North Carolina, USA. Absorption cross sections were deduced for the magnetic and electric and dipole strength distributions separately for various intervals of excitation energy, including the strength of states in the unresolved quasicontinuum. The magnetic dipole strength distributions show structures resembling a resonance in the spin-flip region around an excitation energy of 8 MeV. The electric dipole strength distributions obtained from the present experiments are in agreement with the ones deduced from an earlier experiment using broad-band bremsstrahlung instead of a quasimonoenergetic beam. The experimental magnetic and electric dipole strength distributions are compared with phenomenological approximations and with predictions of a quasiparticle random phase approximation in a deformed basis.
Transparency window for the absorptive dipole resonance in a symmetry-reduced grating structure.
Dong, Zheng-Gao; Ni, Pei-Gen; Zhu, Jie; Zhang, X
2012-03-26
We demonstrate that a transparency window can be obtained within the absorptive dipole resonant regime, by slightly reducing the symmetric arrangement of a dipole-like bar grating covered by a waveguiding layer. The physical understanding is that, under the condition of reducing the grating symmetry, the lossy dipole plasmon resonance can be completely transferred into the waveguide mode in a way of destructive interference. In accompany with the tunable transparency window modulated by the symmetry-reduced displacement, an ultra high group index (slowing down the light) as well as a vortex distribution of the electromagnetic field is found.
Nuclear Resonance Fluorescence off 54Cr: The Onset of the Pygmy Dipole Resonance
NASA Astrophysics Data System (ADS)
Ries, P. C.; Beck, T.; Beller, J.; Krishichayan; Gayer, U.; Isaak, J.; Löher, B.; Mertes, L.; Pai, H.; Pietralla, N.; Romig, C.; Savran, D.; Schilling, M.; Tornow, W.; Werner, V.; Zweidinger, M.
2016-06-01
Low-lying electric and magnetic dipole excitations (E1 and M1) below the neutron separation threshold, particularly the Pygmy Dipole Resonance (PDR), have drawn considerable attention in the last years. So far, mostly moderately heavy nuclei in the mass regions around A = 90 and A = 140 were examined with respect to the PDR. In the present work, the systematics of the PDR have been extended by measuring excitation strengths and parity quantum numbers of J = 1 states in lighter nuclei near A = 50 in order to gather information on the onset of the PDR. The nuclei 50,52,54Cr and 48,50Ti were examined via bremsstrahlung produced at the DArmstadt Superconducting electron Linear Accelerator (S-DALINAC) with photon energies up to 9.7 MeV with the method of nuclear resonance fluorescence. Numerous excited states were observed, many of which for the first time. The parity quantum numbers of these states have been determined at the High Intensity Gamma-ray Source (HIγS) of the Triangle Universities Nuclear Laboratory in Durham, NC, USA. Informations to the methods and the experimental setups will be provided and the results on 54Cr achieved will be discussed with respect to the onset of the PDR.
Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances
NASA Astrophysics Data System (ADS)
Thompson, I. J.; Escher, J. E.; Arbanas, G.
2014-04-01
Semidirect capture, a two-step process that excites a giant-dipole resonance followed by its radiative de-excitation, is a dominant process near giant-dipole resonances, that is, for incoming neutron energies within 5-20 MeV. At lower energies such processes may affect neutron capture rates that are relevant to astrophysical nucleosynthesis models. We implement a semidirect capture model in the coupled-channel reaction code Fresco and validate it by comparing the cross section for direct-semidirect capture 208Pb(n,γ)209Pb to experimental data. We also investigate the effect of low-energy electric dipole strength in the pygmy resonance. We use a conventional single-particle direct-semidirect capture code Cupido for comparison. Furthermore, we present and discuss our results for direct-semidirect capture reaction 130Sn(n,γ)131Sn, the cross section of which is known to have a significant effect on nucleosynthesis models.
Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances
Thompson, I J; Escher, Jutta E; Arbanas, Goran
2013-01-01
Semidirect capture, a two-step process that excites a giant-dipole resonance followed by its radiative de-excitation, is a dominant process near giant-dipole resonances, that is, for incoming neutron energies within 5 20 MeV. At lower energies such processes may affect neutron capture rates that are relevant to astrophysical nucleosynthesis models. We implement a semidirect capture model in the coupled-channel reaction code Fresco and validate it by comparing the cross section for direct-semidirect capture 208Pb(n,g)209Pb to experimental data. We also investigate the effect of low-energy electric dipole strength in the pygmy resonance. We use a conventional single-particle direct-semidirect capture code Cupido for comparison. Furthermore, we present and discuss our results for direct-semidirect capture reaction 130Sn(n,g)131Sn, the cross section of which is known to have a significant effect on nucleosynthesis models.
Point dipole and quadrupole scattering approximation to collectively responding resonator systems
NASA Astrophysics Data System (ADS)
Watson, Derek W.; Jenkins, Stewart D.; Ruostekoski, Janne
2017-07-01
We develop a theoretical formalism for collectively responding point scatterers where the radiating electromagnetic fields from each emitter are considered in the electric dipole, magnetic dipole, and electric quadrupole approximation. The contributions of the electric quadrupole moment to electromagnetically-mediated interactions between the scatterers are derived in detail for a system where each scatterer represents a linear R L C circuit resonator, representing common metamaterial resonators in radiofrequency, microwave, and optical regimes. The resulting theory includes a closed set of equations for an ensemble of discrete resonators that are radiatively coupled to each other by propagating electromagnetic fields, incorporating potentially strong interactions and recurrent scattering processes. The effective model is illustrated and tested for examples of pairs of interacting point electric dipoles, where each pair can be qualitatively replaced by a model point emitter with different multipole radiation moments.
Photon scattering studies of the giant dipole resonance in medium weight nuclei
Bowles, T.J.; Holt, R.J.; Jackson, H.E.; Laszewski, R.M.; McKeown, R.D.; Nathan, A.M.; Specht, J.R.
1981-11-01
Quasimonochromatic photons have been used to measure elastic and inelastic photon scattering cross sections in the giant dipole resonance region of /sup 52/Cr, Fe, /sup 60/Ni, /sup 92/Mo, and /sup 96/Mo in an experiment in which the elastic and inelastic scattering are resolved. The elastic scattering cross sections show clear evidence for isospin splitting of the giant dipole resonance. The inelastic scattering to low-lying vibrational levels, which is a measure of the coupling between the giant dipole resonance and collective surface vibrations, is in qualitative agreement with the predictions of the dynamic collective model. However, when examined in detail, this model does not provide an adequate description of the scattering data.
The role of dipole resonances in the photodetachment of AgF-
NASA Astrophysics Data System (ADS)
Douguet, N.; Dulieu, O.; Fonseca Dos Santos, S.; Kokoouline, V.; Raoult, M.
2016-05-01
Dipole electronic resonances could play a significant role in the formation and photodetachment of negative molecular ions by providing a doorway for attachment of a low-energy electron incident on the neutral molecule. In this study, we consider photodetachment of the AgF-anion. Vibrational and rotational degrees of freedom are included in the theoretical approach. Close-coupling equations for the electron motion are solved using the renormalized Numerov method. The photodetachment cross section is computed. It demonstrates a significant effect of the dipole resonances on the photodetachment spectrum. Anisotropy in the photoelectron spectrum near the dipole resonances is studied. Our results are compared with recent experimental data. Supported by the National Science Foundation, Grant No PHY-15-06391.
NASA Astrophysics Data System (ADS)
Chatzakis, Ioannis; Luo, Liang; Wang, Jigang; Shen, Nian Hai; Koschny, Thomas; Soukoulis, Costas
2011-03-01
Currently, there is strong interest to explore the dynamic control of the electromagnetic properties of metamaterials, which have important implications on their optoelectronic applications. While the design, fabrication and photo-doping of metamaterial/semiconductor structures have been actively pursued, some fundamental issues related to highly photo-excited states, their dynamic tuning and temporal evolution remain open. Using optical-pump terahertz probe spectroscopy, we report on the pump fluence dependence of the electric dipole resonance tunability in metamaterials. We find a previously undiscovered large non-monotonic variation on the strength of the dipole resonance peak with the photo-injected carrier concentration.
Tunable Dipole Surface Plasmon Resonances of Silver Nanoparticles by Cladding Dielectric Layers
Liu, Xiaotong; Li, Dabing; Sun, Xiaojuan; Li, Zhiming; Song, Hang; Jiang, Hong; Chen, Yiren
2015-01-01
The tunability of surface plasmon resonance can enable the highest degree of localised surface plasmon enhancement to be achieved, based on the emitting or absorbing wavelength. In this article, tunable dipole surface plasmon resonances of Ag nanoparticles (NPs) are realized by modification of the SiO2 dielectric layer thicknesses. SiO2 layers both beneath and over the Ag NPs affected the resonance wavelengths of local surface plasmons (LSPs). By adjusting the SiO2 thickness beneath the Ag NPs from 5 nm to 20 nm, the dipole surface plasmon resonances shifted from 470 nm to 410 nm. Meanwhile, after sandwiching the Ag NPs by growing SiO2 before NPs fabrication and then overcoating the NPs with various SiO2 thicknesses from 5 nm to 20 nm, the dipole surface plasmon resonances changed from 450 nm to 490 nm. The SiO2 cladding dielectric layer can tune the Ag NP surface charge, leading to a change in the effective permittivity of the surrounding medium, and thus to a blueshift or redshift of the resonance wavelength. Also, the quadrupole plasmon resonances were suppressed by the SiO2 cladding layer because the dielectric SiO2 can suppress level splitting of surface plasmon resonances caused by the Ag NP coupling effect. PMID:26218501
NASA Astrophysics Data System (ADS)
Zhu, Guo-Zhu; Huang, Dao-Ling; Wang, Lai-Sheng
2017-07-01
We report a photoelectron imaging and photodetachment study of cryogenically cooled 3-hydroxyphenoxide (3HOP) anions, m-HO(C6H4)O-. In a previous preliminary study, two conformations of the cold 3HOP anions with different dipole bound states were observed [D. L. Huang et al., J. Phys. Chem. Lett. 6, 2153 (2015)]. Five near-threshold vibrational resonances were revealed in the photodetachment spectrum from the dipole-bound excited states of the two conformations. Here, we report a more extensive investigation of the two conformers with observation of thirty above-threshold vibrational resonances in a wide spectral range between 18 850 and 19 920 cm-1 (˜1000 cm-1 above the detachment thresholds). By tuning the detachment laser to the vibrational resonances in the photodetachment spectrum, high-resolution conformation-selective resonant photoelectron images are obtained. Using information of the autodetachment channels and theoretical vibrational frequencies, we are able to assign the resonant peaks in the photodetachment spectrum: seventeen are assigned to vibrational levels of anti-3HOP, eight to syn-3HOP, and five to overlapping vibrational levels of both conformers. From the photodetachment spectrum and the conformation-selective resonant photoelectron spectra, we have obtained fourteen fundamental vibrational frequencies for the neutral syn- and anti-m-HO(C6H4)Oṡ radicals. The possibility to produce conformation-selected neutral beams using resonant photodetachment via dipole-bound excited states of anions is discussed.
Nonlinear SU(2,1) Model of Multiple Giant Dipole Resonance Coulomb Excitation
NASA Astrophysics Data System (ADS)
Hussein, Mahir; de Toledo Piza, Antonio; Vorov, Oleg
2000-10-01
We construct a three-dimensional analytically soluble model of the nonlinear effects in Coulomb excitation of multiphonon Giant Dipole Resonances (GDR) based on the SU(2,1) algebra^1. Analytical expressions for the multi-phonon transition probabilities are derived. For reasonably small magnitude of nonlinearity x~= 0.15-0.3, the enhancement factor for the Double Giant Resonance excitation probabilities and the cross sections reaches values 1.3-2 compatible^1,2 with experimental data from relativistic ion collision experiments^3. The full 3-dimensional model predicts enhancement of the multiple GDR cross sections at low and high bombarding energies (with the minimum at ~= 1.3 GeV for the Pb+Pb colliding system). Enhancement factors for Double GDR measured in thirteen different processes with various projectiles and targets at different bombarding energies are well reproduced with the same value of the nonlinearity parameter with the exception of the anomalous case of ^136Xe which requires a larger value. The work has been supported by the FAPESP and by the CNPq. References ^1 M. S. Hussein, A. F. R. de Toledo Piza and O. K.Vorov, Ann. Phys. (N.Y.), 2000, to appear. ^2 M. S. Hussein, A. F. R. de Toledo Piza and O. K.Vorov, Phys. Rev. C59,R1242 (1999). ^3 T. Aumann, P.F. Bortignon, and H. Emling, Annu. Rev. Nucl. Part. Sci. 48, 351 (1998).
Giant dipole resonance in very hot nuclei of mass A~=115
NASA Astrophysics Data System (ADS)
Suomijärvi, T.; Blumenfeld, Y.; Piattelli, P.; Le Faou, J. H.; Agodi, C.; Alamanos, N.; Alba, R.; Auger, F.; Bellia, G.; Chomaz, Ph.; Coniglione, R.; del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Gaardhøje, J. J.; Garron, J. P.; Gillibert, A.; Lamehi-Rachti, M.; Liguori-Neto, R.; Maiolino, C.; Migneco, E.; Russo, G.; Roynette, J. C.; Santonocito, D.; Sapienza, P.; Scarpaci, J. A.; Smerzi, A.
1996-05-01
Gamma rays, light charged particles, and evaporation residues emitted from hot nuclei formed in the 36Ar+90Zr reaction at 27 MeV/nucleon have been measured at the GANIL facility with the 4π barium fluoride multidetector MEDEA. The combination of the residue and particle measurements shows that nuclei with masses around 115 and excitation energies between 350 and 550 MeV are produced. The γ spectra measured in coincidence with the evaporation residues exhibit three components: a low-energy statistical component, a high-energy contribution due to nucleon-nucleon bremsstrahlung during the initial stages of the collision, and a contribution from the decay of the giant dipole resonance built on highly excited states. The characteristics of the bremsstrahlung component are in agreement with previously published systematics. The γ yield from the decay of the giant dipole resonance remains constant over the excitation energy range studied. A comparison with other experiments shows that the N/Z asymmetry in the entrance channel does not affect the γ yield. Statistical calculations performed using the code CASCADE and supposing a fixed width and full sum rule strength for the dipole resonance strongly overpredict the data. The hypothesis of a continuously increasing width of the resonance with temperature gives a better agreement with experiment near the centroid of the resonance but overpredicts the γ spectra at higher energies. The best account of the data is given by assuming a cutoff of γ emission from the resonance above an excitation energy of approximately 250 MeV. This cutoff is discussed in terms of the time necessary to equilibrate the dipole oscillations with the hot compound nucleus. Finally, some evidence is given for a possible new low-energy component of the dipole strength at very high temperatures.
NASA Technical Reports Server (NTRS)
Ding, D. Q.; Denton, . E.; Hudson, M. K.; Lysak, R. L.
1995-01-01
The poloidal mode field line resonance in the Earth's dipole magnetic field is investigated using cold plasma ideal MHD simulations in dipole geometry. In order to excite the poloidal mode resonance, we use either an initial or a continuous velocity perturbation to drive the system. The perturbation is localized at magnetic shell L = 7 with plasma flow in the radial direction (electric field component in the azimuthal direction). It is found that with the initial perturbation alone, no polodial mode resonance can be obtained and the initially localized perturbation spreads out across all magnetic L shells. With the continuous perturbation, oscillating near the poloidal resonance frequency, a global-scale poloidal cavity mode can be obtained. For the first time, a localized guided poloidal mode resonance is obtained when a radial component of electric field is added to the initial perturbation such that the curl of the electric field is everywhere perpendicular to the background dipole magnetic field. During the localized poloidal resonance, plasma vortices parallel/antiparallel to the background dipole magnetic field B(sub 0). This circular flow, elongated radially, results in twisting of magnetic field flux tubes, which, in turn, leads to the slowdown of the circular plasma flow and reversal of the plasma vortices. The energy associated with the localized poloidal resonance is conserved as it shifts back and forth between the oscillating plasma vortices and the alternately twisted magnetic flux tubes. In the simulations the eigenfunctions associated with the localized poloidal resonance are grid-scale singular functions. This result indicates that ideal MHD is inadequate to describe the underlying problem and nonideal MHD effects are needed for mode broadening.
Design Concept and Parameters of a 15 T $Nb_{3}Sn$ Dipole Demonstrator for a 100 TEV Hadron Collider
Zlobin, A. V.; Andreev, N.; Barzi, E.; Kashikhin, V. V.; Novitski, I.
2015-06-01
FNAL has started the development of a 15 T $Nb_{3}Sn$ dipole demonstrator for a 100 TeV scale hadron collider. This paper describes the design concept and parameters of the 15 T $Nb_{3}Sn$ dipole demonstrator. The dipole magnetic, mechanical and quench protection concept and parameters are presented and discussed.
The Isoscalar Giant Dipole Resonance in {sup 20}Pb, {sup 90}Zr and the Nuclear Compressibility
Yildirim, Serbulent; Koeroglu, Ulas
2008-11-11
The isoscalar giant dipol resonance (ISGDR) in finite nuclei is studied within the framework of a relativistic transport approach. The excitation energies of spherical {sup 90}Zr and {sup 208}Pb nuclei are obtained for different quantum hydrodynamical Lagrangian parametrization. The sensitivity of ISGDR excitation energy on the nuclear bulk to surface properties are also investigated.
Evolution of the pygmy dipole resonance in Sn isotopes
NASA Astrophysics Data System (ADS)
Toft, H. K.; Larsen, A. C.; Bürger, A.; Guttormsen, M.; Görgen, A.; Nyhus, H. T.; Renstrøm, T.; Siem, S.; Tveten, G. M.; Voinov, A.
2011-04-01
Nuclear level density and γ-ray strength functions of Sn121,122 below the neutron separation energy are extracted with the Oslo method using the (He3,He3'γ) and (He3,αγ) reactions. The level densities of Sn121,122 display steplike structures, interpreted as signatures of neutron pair breaking. An enhancement in both strength functions, compared to standard models for radiative strength, is observed in our measurements for Eγ≳5.2 MeV. This enhancement is compatible with pygmy resonances centered at ≈8.4(1) and ≈8.6(2) MeV, respectively, and with integrated strengths corresponding to ≈1.8-5+1% of the classical Thomas-Reiche-Kuhn sum rule. Similar resonances were also seen in Sn116-119. Experimental neutron-capture cross reactions are well reproduced by our pygmy resonance predictions, while standard strength models are less successful. The evolution as a function of neutron number of the pygmy resonance in Sn116-122 is described as a clear increase of centroid energy from 8.0(1) to 8.6(2) MeV, but with no observable difference in integrated strengths.
NASA Astrophysics Data System (ADS)
Bastrukov, S. I.; Molodtsova, I. V.; Podgainy, D. V.; Mişicu, Ş.; Chang, H.-K.
2008-06-01
Motivated by arguments of the nuclear core-layer model formulated in [S.I. Bastrukov, J.A. Maruhn, Z. Phys. A 335 (1990) 139], the macroscopic excitation mechanism of the electric pygmy dipole resonance (PDR) is considered as owing its origin to perturbation-induced effective decomposition of a nucleus into two spherical domains-undisturbed inner region treated as a static core and dynamical layer undergoing elastic shear vibrations. The elastic restoring force is central to the excitation mechanism under consideration and has the same physical meaning as in macroscopic model of nuclear giant resonances involving distortions of the Fermi-sphere providing unified description of isoscalar giant electric and magnetic resonances of multipole degree ℓ ⩾ 2 in terms of two fundamental vibrational modes in an elastic sphere, to wit, as spheroidal (electric) and torsional (magnetic) modes of shear elastic oscillations of the nodeless field of material displacements excited in the entire nucleus volume. In the present Letter focus is placed on the emergence of dipole overtone in the frequency spectrum of spheroidal elastic vibrations as Goldstone soft mode. To emphasis this feature of dipole resonant excitation imprinted in the core-layer model we regain spectral equation for the frequency of spheroidal elastic vibrations trapped in the finite-depth layer, derived in the above paper, but using canonical equation of an elastic continuous medium. The obtained analytic equations for the frequency of dipole vibrational state in question and its excitation strength lead to the following estimates for the PDR energy centroid EPDR (E 1) = [ 31 ± 1 ]A - 1 / 3 MeV and the total excitation probability BPDR (E 1) = [ 1.85 ± 0.05 ]10-3Z2A - 2 / 3e2fm2 throughout the nuclear chart exhibiting fundamental character of this soft dipole mode of nuclear resonant response.
Optical Control of the Resonant Dipole-Dipole Interaction between Rydberg Atoms
NASA Astrophysics Data System (ADS)
de Léséleuc, Sylvain; Barredo, Daniel; Lienhard, Vincent; Browaeys, Antoine; Lahaye, Thierry
2017-08-01
We report on the local control of the transition frequency of a spin 1 /2 encoded in two Rydberg levels of an individual atom by applying a state-selective light shift using an addressing beam. With this tool, we first study the spectrum of an elementary system of two spins, tuning it from a nonresonant to a resonant regime, where "bright" (super-radiant) and "dark" (subradiant) states emerge. We observe the collective enhancement of the microwave coupling to the bright state. We then show that after preparing an initial single spin excitation and letting it hop due to the spin-exchange interaction, we can freeze the dynamics at will with the addressing laser, while preserving the coherence of the system. In the context of quantum simulation, this scheme opens exciting prospects for engineering inhomogeneous X Y spin Hamiltonians or preparing spin-imbalanced initial states.
Finite amplitude method applied to the giant dipole resonance in heavy rare-earth nuclei
NASA Astrophysics Data System (ADS)
Oishi, Tomohiro; Kortelainen, Markus; Hinohara, Nobuo
2016-03-01
Background: The quasiparticle random phase approximation (QRPA), within the framework of nuclear density functional theory (DFT), has been a standard tool to access the collective excitations of atomic nuclei. Recently, the finite amplitude method (FAM) was developed in order to perform the QRPA calculations efficiently without any truncation on the two-quasiparticle model space. Purpose: We discuss the nuclear giant dipole resonance (GDR) in heavy rare-earth isotopes, for which the conventional matrix diagonalization of the QRPA is numerically demanding. A role of the Thomas-Reiche-Kuhn (TRK) sum rule enhancement factor, connected to the isovector effective mass, is also investigated. Methods: The electric dipole photoabsorption cross section was calculated within a parallelized FAM-QRPA scheme. We employed the Skyrme energy density functional self-consistently in the DFT calculation for the ground states and FAM-QRPA calculation for the excitations. Results: The mean GDR frequency and width are mostly reproduced with the FAM-QRPA, when compared to experimental data, although some deficiency is observed with isotopes heavier than erbium. A role of the TRK enhancement factor in actual GDR strength is clearly shown: its increment leads to a shift of the GDR strength to higher-energy region, without a significant change in the transition amplitudes. Conclusions: The newly developed FAM-QRPA scheme shows remarkable efficiency, which enables one to perform systematic analysis of GDR for heavy rare-earth nuclei. The theoretical deficiency of the photoabsorption cross section could not be improved by only adjusting the TRK enhancement factor, suggesting the necessity of an approach beyond self-consistent QRPA and/or a more systematic optimization of the energy density functional (EDF) parameters.
Effects of Meandering on Dipole Antenna Resonant Frequency
2012-01-01
predicted to be 238.3 MHz using (1) from [12] (1) Shifting the resonant frequency of an antenna downwards is generally a method to improve the radiation...geometry constant during mea- surement. The XEPS is transparent at microwave frequencies and thus does not measurably perturb the antenna impedance... Methods for modeling wire antennas loaded with shielded networks,” IEEE Trans. Antennas Propag., vol. 52, no. 4, pp. 961–968, Apr. 2004. [4] E. W
Neutron Resonance Parameters for Cm-242 (Curium)
NASA Astrophysics Data System (ADS)
Sukhoruchkin, S. I.; Soroko, Z. N.
This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Cm-242 (Curium).
Neutron Resonance Parameters for Np-237 (Neptunium)
NASA Astrophysics Data System (ADS)
Sukhoruchkin, S. I.; Soroko, Z. N.
This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Np-237 (Neptunium).
Resonant properties of dipole skyrmions in amorphous Fe/Gd multilayers
NASA Astrophysics Data System (ADS)
Montoya, S. A.; Couture, S.; Chess, J. J.; Lee, J. C. T.; Kent, N.; Im, M.-Y.; Kevan, S. D.; Fischer, P.; McMorran, B. J.; Roy, S.; Lomakin, V.; Fullerton, E. E.
2017-06-01
The dynamic response of dipole skyrmions in Fe/Gd multilayer films is investigated by ferromagnetic resonance measurements and compared to micromagnetic simulations. We detail thickness- and temperature-dependent studies of the observed modes as well as the effects of magnetic field history on the resonant spectra. Correlation between the modes and the magnetic phase maps constructed from real-space imaging and scattering patterns allows us to conclude that the resonant modes arise from local topological features such as dipole skyrmions but do not depend on the collective response of a close-packed lattice of these chiral textures. Using micromagnetic modeling, we are able to quantitatively reproduce our experimental observations which suggests the existence of localized spin-wave modes that are dependent on the helicity of the dipole skyrmion. We identify four localized spin-wave excitations for the skyrmions that are excited under either in-plane or out-of-plane rf fields. Lastly we show that dipole skyrmions and nonchiral bubble domains exhibit qualitatively different localized spin-wave modes.
The decay pattern of the Pygmy Dipole Resonance of 140Ce
NASA Astrophysics Data System (ADS)
Löher, B.; Savran, D.; Aumann, T.; Beller, J.; Bhike, M.; Cooper, N.; Derya, V.; Duchêne, M.; Endres, J.; Hennig, A.; Humby, P.; Isaak, J.; Kelley, J. H.; Knörzer, M.; Pietralla, N.; Ponomarev, V. Yu.; Romig, C.; Scheck, M.; Scheit, H.; Silva, J.; Tonchev, A. P.; Tornow, W.; Wamers, F.; Weller, H.; Werner, V.; Zilges, A.
2016-05-01
The decay properties of the Pygmy Dipole Resonance (PDR) have been investigated in the semi-magic N = 82 nucleus 140Ce using a novel combination of nuclear resonance fluorescence and γ-γ coincidence techniques. Branching ratios for transitions to low-lying excited states are determined in a direct and model-independent way both for individual excited states and for excitation energy intervals. Comparison of the experimental results to microscopic calculations in the quasi-particle phonon model exhibits an excellent agreement, supporting the observation that the Pygmy Dipole Resonance couples to the ground state as well as to low-lying excited states. A 10% mixing of the PDR and the [21+ × PDR ] is extracted.
Evidence of Soft Dipole Resonance in ^{11}Li with Isoscalar Character
Kanungo, R.; Sanetullaev, A.; Jansen, Gustav R.; Tanaka, J.; Ishimoto, S.; Myo, T.; Suzuki, T.; Andreoiu, C.; Bender, P.; Chen, A. A.; Davids, B.; Fallis, J.; Fortin, J. P.; Galinski, N.; Gallant, A. T.; Garrett, P. E.; Hackman, G.; Hadinia, B.; Hagen, Gaute; Keefe, M.; Krucken, R.; Lighthall, J.; McNeice, E.; Miller, D.; Otsuka, T.; Purcell, J.; Randhawa, J. S.; Roger, T.; Rojas, A.; Savajols, H.; Shotter, A.; Tanihata, I.; Thompson, I. J.; Unsworth, C.; Voss, P.; Wang, Z.
2015-05-12
The first conclusive evidence of a dipole resonance in ^{11}Li having isoscalar character observed from inelastic scattering with a novel solid deuteron target is reported. The experiment was performed at the newly commissioned IRIS facility at TRIUMF. The results show a resonance peak at an excitation energy of 1.03±0.03 MeV with a width of 0.51±0.11 MeV (FWHM). The angular distribution is consistent with a dipole excitation in the distorted-wave Born approximation framework. The observed resonance energy together with shell model calculations show the first signature that the monopole tensor interaction is important in ^{11}Li. The first ab initio calculations in the coupled cluster framework are also included.
Evidence of Soft Dipole Resonance in 11Li with Isoscalar Character
Kanungo, R.; Sanetullaev, A.; Jansen, Gustav R.; ...
2015-05-12
The first conclusive evidence of a dipole resonance in 11Li having isoscalar character observed from inelastic scattering with a novel solid deuteron target is reported. The experiment was performed at the newly commissioned IRIS facility at TRIUMF. The results show a resonance peak at an excitation energy of 1.03±0.03 MeV with a width of 0.51±0.11 MeV (FWHM). The angular distribution is consistent with a dipole excitation in the distorted-wave Born approximation framework. The observed resonance energy together with shell model calculations show the first signature that the monopole tensor interaction is important in 11Li. The first ab initio calculations inmore » the coupled cluster framework are also included.« less
The decay pattern of the Pygmy Dipole Resonance of 140 Ce
Löher, B.; Savran, D.; Aumann, T.; ...
2016-05-01
The decay properties of the Pygmy Dipole Resonance (PDR) have been investigated in the semi-magic N=82 nucleus 140Ce using a novel combination of nuclear resonance fluorescence and γ–γ coincidence techniques. Branching ratios for transitions to low-lying excited states are determined in a direct and model-independent way both for individual excited states and for excitation energy intervals. Comparison of the experimental results to microscopic calculations in the quasi-particle phonon model exhibits an excellent agreement, supporting the observation that the Pygmy Dipole Resonance couples to the ground state as well as to low-lying excited states. A 10% mixing of the PDR andmore » the [21+×PDR] is extracted.« less
The decay pattern of the Pygmy Dipole Resonance of ^{140} Ce
Löher, B.; Savran, D.; Aumann, T.; Beller, J.; Bhike, M.; Cooper, N.; Derya, V.; Duchêne, M.; Endres, J.; Hennig, A.; Humby, P.; Isaak, J.; Kelley, J. H.; Knörzer, M.; Pietralla, N.; Ponomarev, V. Yu.; Romig, C.; Scheck, M.; Scheit, H.; Silva, J.; Tonchev, A. P.; Tornow, W.; Wamers, F.; Weller, H.; Werner, V.; Zilges, A.
2016-05-01
The decay properties of the Pygmy Dipole Resonance (PDR) have been investigated in the semi-magic N=82 nucleus ^{140}Ce using a novel combination of nuclear resonance fluorescence and γ–γ coincidence techniques. Branching ratios for transitions to low-lying excited states are determined in a direct and model-independent way both for individual excited states and for excitation energy intervals. Comparison of the experimental results to microscopic calculations in the quasi-particle phonon model exhibits an excellent agreement, supporting the observation that the Pygmy Dipole Resonance couples to the ground state as well as to low-lying excited states. A 10% mixing of the PDR and the [21+×PDR] is extracted.
Microscopic nature of the pygmy dipole resonance: the stable Ca isotopes.
Hartmann, T; Babilon, M; Kamerdzhiev, S; Litvinova, E; Savran, D; Volz, S; Zilges, A
2004-11-05
The electric dipole strength distribution in 44Ca has been measured up to 10 MeV in high resolution photon scattering experiments for the first time. The data obtained have been compared to earlier measurements on (40,48)Ca in order to view the evolution of the electric pygmy dipole resonance (PDR). Calculations that were performed within the framework of the microscopic extended theory of finite Fermi systems, which adds contributions of the quasiparticle-phonon coupling to random phase approximation calculations, give a qualitative agreement with the experimental data for all three isotopes. We have shown that it is necessary to include this coupling to describe the PDR.
Integral data analysis for resonance parameters determination
Larson, N.M.; Leal, L.C.; Derrien, H.
1997-09-01
Neutron time-of-flight experiments have long been used to determine resonance parameters. Those resonance parameters have then been used in calculations of integral quantities such as Maxwellian averages or resonance integrals, and results of those calculations in turn have been used as a criterion for acceptability of the resonance analysis. However, the calculations were inadequate because covariances on the parameter values were not included in the calculations. In this report an effort to correct for that deficiency is documented: (1) the R-matrix analysis code SAMMY has been modified to include integral quantities of importance, (2) directly within the resonance parameter analysis, and (3) to determine the best fit to both differential (microscopic) and integral (macroscopic) data simultaneously. This modification was implemented because it is expected to have an impact on the intermediate-energy range that is important for criticality safety applications.
Limiting Temperatures for Collective Motion: The Giant Dipole Resonance in Very Hot Nuclei
NASA Astrophysics Data System (ADS)
Piattelli, P.; Blumenfeld, Y.; Le Faou, J. H.; Suomijärvi, T.; Agodi, C.; Alamanos, N.; Alba, R.; Auger, F.; Bellia, G.; Chomaz, Ph.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Gaardhøje, J. J.; Garron, J. P.; Gillibert, A.; Lamehi-Rachti, M.; Liguori-Neto, R.; Loukachine, K.; Maiolino, C.; Migneco, E.; Roynette, J. C.; Santonocito, D.; Sapienza, P.; Scarpaci, J. A.
1996-02-01
The study of the Giant Dipole Resonance (GDR) excited in hot nuclei allows to follow the evolution of collective motion with increasing nuclear temperature. A brief review of the characteristics of the GDR excited in nuclei with excitation energies up to ˜ 500 MeV is given. The results of recent experiments in which very hot nuclei have been studied with a nearly 4π detector are presented. Gamma-rays, light charged particles and evaporation residues emitted from hot nuclei of mass around 115 and excitation energies above 300 MeV, formed in the 36Ar + 90Zr at 27 MeV/u and 36Ar + 98Mo at 37 MeV/u reactions, have been measured with the MEDEA multidetector. The γ-ray yield from the decay of the Giant Dipole Resonance in these nuclei has been found to be independent of excitation energy and bombarding energy. The measured γ-ray spectra are compared with statistical calculations encompassing several recent theoretical models for the quenching of gamma-ray emission from the dipole resonance at very high temperatures. The best agreement with the data is obtained by assuming a cut-off of the resonance γ-emission above an excitation energy of 250 MeV.
Low-lying dipole resonance in neutron-rich Ne isotopes
NASA Astrophysics Data System (ADS)
Yoshida, Kenichi; van Giai, Nguyen
2008-07-01
Microscopic structure of the low-lying isovector dipole excitation mode in neutron-rich Ne26,28,30 is investigated by performing deformed quasiparticle-random-phase-approximation (QRPA) calculations. The particle-hole residual interaction is derived from a Skyrme force through a Landau-Migdal approximation. We obtain the low-lying resonance in Ne26 at around 8.6 MeV. It is found that the isovector dipole strength at Ex<10 MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule. This excitation mode is composed of several QRPA eigenmodes, one is generated by a ν(2s1/2-12p3/2) transition dominantly and the other mostly by a ν(2s1/2-12p1/2) transition. The neutron excitations take place outside of the nuclear surface reflecting the spatially extended structure of the 2s1/2 wave function. In Ne30, the deformation splitting of the giant resonance is large, and the low-lying resonance overlaps with the giant resonance.
Temperature dependence of the giant dipole resonance width in 152Gd
NASA Astrophysics Data System (ADS)
Ghosh, C.; Mishra, G.; Rhine Kumar, A. K.; Dokania, N.; Nanal, V.; Pillay, R. G.; Kumar, Suresh; Rout, P. C.; Joshi, Sandeep; Arumugam, P.
2016-07-01
To investigate the dependence of giant dipole resonance (GDR) width on temperature (T ) and angular momentum (J ), high energy γ -ray spectra were measured in the reaction 28Si+124Sn at E28Si=135 MeV. The J information was deduced from multiplicity of low-energy γ rays. The GDR parameters, namely, the centroid energy and width are extracted using statistical model analysis. The observed variation of the GDR width for T ˜1.2 -1.37 MeV and J ˜20 ℏ -40 ℏ is consistent with the universal scaling given by Kusnezov et al., which is applicable in the liquid-drop regime. The GDR input cross sections extracted from the statistical model best fits are compared with thermal shape fluctuation model (TSFM) calculations and are found to be in good agreement. The TSFM calculations predominantly favor the noncollective oblate shape, while the statistical model fit with both prolate and oblate shapes describes the data. The present data together with earlier measurements indicate a very slow variation of the GDR width for T ˜1.2 to 1.5 MeV. The observed trend is well explained by the TSFM calculations, although the calculated values are ˜4 %-13% higher than the data.
Giant dipole resonance studies in Ba isotopes at E /A ≈5 MeV
NASA Astrophysics Data System (ADS)
Ghosh, C.; Kumar, A. K. Rhine; Dey, Balaram; Nanal, V.; Pillay, R. G.; Arumugam, P.; Anoop, K. V.; Dokania, N.; Garai, Abhijit; Gupta, Ghnashyam; Mirgule, E. T.; Mishra, G.; Mondal, Debasish; Pal, S.; Pose, M. S.; Rout, P. C.
2017-07-01
Exclusive measurements of high-energy γ rays have been performed in 124Ba and 136Ba at the same excitation energy (˜49 MeV ) to study the properties of the giant dipole resonance (GDR) over a wide N /Z range. The high-energy γ rays are measured in coincidence with the multiplicity of low-energy γ rays to disentangle the effect of temperature (T ) and angular momentum (J ). The GDR parameters are extracted employing a simulated Monte Carlo statistical model analysis. The observed γ -ray spectra of 124Ba can be explained with prolate deformation, whereas a single-component Lorentzian function which corresponds to a spherical shape could explain the γ -ray spectra of 136Ba. The observed GDR width in 136Ba is narrower compared to that of 124Ba. The statistical model best-fit GDR cross sections are found to be in reasonable agreement with the thermal shape fluctuation model (TSFM) calculations. Further, it is shown that the variation of GDR width with T is well reproduced by the TSFM calculations over the temperature range of 1.1-1.7 MeV.
Experimental study of the isovector giant dipole resonance in 80Zr and 81Rb
NASA Astrophysics Data System (ADS)
Ceruti, S.; Camera, F.; Bracco, A.; Mentana, A.; Avigo, R.; Benzoni, G.; Blasi, N.; Bocchi, G.; Bottoni, S.; Brambilla, S.; Crespi, F. C. L.; Giaz, A.; Leoni, S.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Wieland, O.; Bazzacco, D.; Ciemala, M.; Farnea, E.; Gottardo, A.; Kmiecik, M.; Maj, A.; Mengoni, D.; Michelagnoli, C.; Modamio, V.; Montanari, D.; Napoli, D.; Recchia, F.; Sahin, E.; Ur, C.; Valiente-Dobón, J. J.; Wasilewska, B.; Zieblinski, M.
2017-01-01
The isovector giant dipole resonance (IVGDR) γ decay was measured in the compound nuclei 80Zr and 81Rb at an excitation energy of E*=54 MeV. The fusion reaction 40Ca+40Ca at Ebeam=136 MeV was used to form the compound nucleus 80Zr, while the reaction 37Cl+44Ca at Ebeam=95 MeV was used to form the compound nucleus 81Rb at the same excitation energy. The IVGDR parameters extracted from the analysis were compared with the ones found at higher excitation energy (E*=83 MeV). The comparison allows one to observe two different nuclear mechanisms: (i) the IVGDR intrinsic width remains constant with the excitation energy in the nucleus 81Rb; (ii) the isospin-violating spreading width (i.e., Coulomb spreading width) remains constant with the excitation energy in the nucleus 80Zr. The experimental setup used for the γ -ray detection was composed by the AGATA demonstrator array coupled to the large-volume LaBr3:Ce detectors of the HECTOR+ array.
Electric dipole strength distribution below the E1 giant resonance in N = 82 nuclei
NASA Astrophysics Data System (ADS)
Guliyev, Ekber; Kuliev, Ali; Guner, Mehmet
2010-12-01
In this study quasiparticle random-phase approximation with the translational invariant Hamiltonian using deformed mean field potential has been conducted to describe electric dipole excitations in 136Xe, 138Ba, 140Ce, 142Nd, 144Sm and 146Gd isotones. The distribution of the calculated E1 strength shows a resonance like structure at energies between 6-8 MeV exhausting up to 1% of the isovector electric dipole Energy Weighted Sum Rule and in some aspects nicely confirms the experimental data. It has been shown that the main part of E1 strength, observed below the threshold in these nuclei may be interpreted as main fragments of the Pygmy Dipole resonance. The agreement between calculated mean excitation energies as well as summed B(E1) value of the 1- excitations and the available experimental data is quite good. The calculations indicate the presence of a few prominent positive parity 1+ States in heavy N = 82 isotones in the energy interval 6-8 MeV which shows not all dipole excitations were of electric character in this energy range.
Electric dipole strength distribution below the E1 giant resonance in N = 82 nuclei
NASA Astrophysics Data System (ADS)
Guliyev, Ekber; Kuliev, Ali; Guner, Mehmet
2010-12-01
In this study quasiparticle random-phase approximation with the translational invariant Hamiltonian using deformed mean field potential has been conducted to describe electric dipole excitations in 136Xe, 138Ba, 140Ce, 142Nd, 144Sm and 146Gd isotones. The distribution of the calculated E1 strength shows a resonance like structure at energies between 6-8 MeV exhausting up to 1% of the isovector electric dipole Energy Weighted Sum Rule and in some aspects nicely confirms the experimental data. It has been shown that the main part of E1 strength, observed below the threshold in these nuclei may be interpreted as main fragments of the Pygmy Dipole resonance. The agreement between calculated mean excitation energies as well as summed B( E1) value of the 1- excitations and the available experimental data is quite good. The calculations indicate the presence of a few prominent positive parity 1+ States in heavy N = 82 isotones in the energy interval 6-8 MeV which shows not all dipole excitations were of electric character in this energy range.
The Giant Dipole Resonance built on highly excited states — results of the MEDEA experiment
NASA Astrophysics Data System (ADS)
Suomijärvi, T.; Le Faou, J. H.; Blumenfeld, Y.; Piattelli, P.; Agodi, C.; Alamanos, N.; Alba, R.; Auger, F.; Bellia, G.; Chomaz, Ph.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Gaardhøje, J. J.; Garron, J. P.; Gillibert, A.; Lamehi-Rachti, M.; Liguori-Neto, R.; Maiolino, C.; Migneco, E.; Russo, G.; Roynette, J. C.; Santonocito, D.; Sapienza, P.; Scarpaci, J. A.; Smerzi, A.
1994-03-01
Gamma-rays, light charged particles and evaporation residues emitted from hot nuclei formed in the 36Ar + 90Zr reaction at 27 MeV/u have been measured with a nearly 4π barium fluoride multidetector. It is shown that hot Sn-like nuclei with a range of excitation energies between 300 and 600 MeV are produced. The γ-ray yield from the decay of the Giant Dipole Resonance in these nuclei is shown to remain constant over this excitation energy range. The measured γ-ray spectra are compared with statistical calculations encompassing several recent theoretical models for the quenching of gamma-ray emission from the dipole resonance at very high temperatures.
Study of the Pygmy Dipole Resonance with Hadronic and Electromagnetic Probes
NASA Astrophysics Data System (ADS)
Endres, J.; Zilges, A.; Litvinova, E.; Savran, D.; Butler, P. A.; Herzberg, R.-D.; Harakeh, M. N.; Stoica, V. I.; Wörtche, H. J.; Harissopulos, S.; Lagoyannis, A.; Krücken, R.; Ring, P.; Pietralla, N.; Ponomarev, V. Yu.; Scheck, M.; Sonnabend, K.; Popescu, L.
2013-03-01
The structure of the pygmy dipole resonance has been investigated in the nuclei 140Ce, 138Ba, 124Sn, and 94Mo by performing experiments using different probes. On the one hand, real-photon scattering experiments have been conducted using the nuclear resonance fluorescence (NRF) method. On the other hand, α-scattering experiments have been done using the (α, α', γ) coincidence technique. An unexpected difference in the excitation cross sections of the dipole strength below the particle threshold has been observed. While a group of PDR states could be excited in both kinds of experiments, a group of energetically higher-lying states could only be excited in NRF. In order to understand this phenomenon, theoretical calculations using the quasiparticle-phonon model (QPM) and the relativistic quasiparticle time-blocking approximation (RQTBA) have been performed for the nucleus 124Sn. A possible explanation for the observed splitting was found.
Recent results on giant dipole resonance decays in highly excited nuclei
Snover, K.A.
1991-12-31
Some recent results on Giant Dipole Resonance (GDR) decays in highly excited, equilibrated nuclei, are discussed based primarily on work done at Seattle. Four sections address the following topics: oblate shapes of rotating, highly excited Zr--Mo nuclei; adiabatic versus `motionally narrowed` GDR decay; large spin-driven deformations observed in hot medium-mass nuclei; and search for entrance channel effects in GDR decay following {sup 58}Ni {plus} {sup 92}Zr fusion. 22 refs.
Recent results on giant dipole resonance decays in highly excited nuclei
Snover, K.A.
1991-01-01
Some recent results on Giant Dipole Resonance (GDR) decays in highly excited, equilibrated nuclei, are discussed based primarily on work done at Seattle. Four sections address the following topics: oblate shapes of rotating, highly excited Zr--Mo nuclei; adiabatic versus motionally narrowed' GDR decay; large spin-driven deformations observed in hot medium-mass nuclei; and search for entrance channel effects in GDR decay following [sup 58]Ni [plus] [sup 92]Zr fusion. 22 refs.
Resolving spin-orbit- and hyperfine-mediated electric dipole spin resonance in a quantum dot.
Shafiei, M; Nowack, K C; Reichl, C; Wegscheider, W; Vandersypen, L M K
2013-03-08
We investigate the electric manipulation of a single-electron spin in a single gate-defined quantum dot. We observe that so-far neglected differences between the hyperfine- and spin-orbit-mediated electric dipole spin resonance conditions have important consequences at high magnetic fields. In experiments using adiabatic rapid passage to invert the electron spin, we observe an unusually wide and asymmetric response as a function of the magnetic field. Simulations support the interpretation of the line shape in terms of four different resonance conditions. These findings may lead to isotope-selective control of dynamic nuclear polarization in quantum dots.
Effects of head models and dipole source parameters on EEG fields.
Peng, Li; Peng, Mingming; Xu, Anhuai
2015-01-01
Head model and an efficient method for computing the forward EEG (electroencephalography)problem are essential to dipole source localization(DSL). In this paper, we use less expensive ovoid geometry to approximate human head, aiming at investigating the effects of head shape and dipole source parameters on EEG fields. The application of point least squares (PLS) based on meshless method was introduced for solving EEG forward problem and numerical simulation is implemented in three kinds of ovoid head models. We present the performances of the surface potential in the face of varying dipole source parameters in detail. The results show that the potential patterns are similar for different dipole position in different head shapes, but the peak value of potential is significantly influenced by the head shape. Dipole position induces a great effect on the peak value of potential and shift of peak potential. The degree of variation between sphere head model and non-sphere head models is seen at the same time. We also show that PLS method with the trigonometric basis is superior to the constant basis, linear basis, and quadratic basis functions in accuracy and efficiency.
Effects of Head Models and Dipole Source Parameters on EEG Fields
Peng, Li; Peng, Mingming; Xu, Anhuai
2015-01-01
Head model and an efficient method for computing the forward EEG (electroencephalography)problem are essential to dipole source localization(DSL). In this paper, we use less expensive ovoid geometry to approximate human head, aiming at investigating the effects of head shape and dipole source parameters on EEG fields. The application of point least squares (PLS) based on meshless method was introduced for solving EEG forward problem and numerical simulation is implemented in three kinds of ovoid head models. We present the performances of the surface potential in the face of varying dipole source parameters in detail. The results show that the potential patterns are similar for different dipole position in different head shapes, but the peak value of potential is significantly influenced by the head shape. Dipole position induces a great effect on the peak value of potential and shift of peak potential. The degree of variation between sphere head model and non-sphere head models is seen at the same time. We also show that PLS method with the trigonometric basis is superior to the constant basis, linear basis, and quadratic basis functions in accuracy and efficiency. PMID:25893011
NASA Astrophysics Data System (ADS)
Musorin, A. I.; Barsukova, M. G.; Shorokhov, A. S.; Neshev, D. N.; Kivshar, Y. S.; Fedyanin, A. A.
2017-09-01
The advantages of gyrotopic materials are combined with the field of high-index metamaterials. The enhancement of the magneto-optical response in the spectral vicinity of the magnetic dipole resonance of a dielectric silicon nanodisks is numerically shown.
Resonance parameter analysis with SAMMY
Larson, N.M.; Perey, F.G.
1988-01-01
The multilevel R-matrix computer code SAMMY has evolved over the past decade to become an important analysis tool for neutron data. SAMMY uses the Reich-Moore approximation to the multilevel R-matrix and includes an optional logarithmic parameterization of the external R-function. Doppler broadening is simulated either by numerical integration using the Gaussian approximation to the free gas model or by a more rigorous solution of the partial differential equation equivalent to the exact free gas model. Resolution broadening of cross sections and derivatives also has new options that more accurately represent the experimental situation. SAMMY treats constant normalization and some types of backgrounds directly and treats other normalizations and/or backgrounds with the introduction of user-generated partial derivatives. The code uses Bayes' method as an efficient alternative to least squares for fitting experimental data. SAMMY allows virtually any parameter to be varied and outputs values, uncertainties, and covariance matrix for all varied parameters. Versions of SAMMY exist for VAX, FPS, and IBM computers.
NASA Astrophysics Data System (ADS)
Ciemała, M.; Kmiecik, M.; Maj, A.; Mazurek, K.; Bracco, A.; Kravchuk, V. L.; Casini, G.; Barlini, S.; Baiocco, G.; Bardelli, L.; Bednarczyk, P.; Benzoni, G.; Bini, M.; Blasi, N.; Brambilla, S.; Bruno, M.; Camera, F.; Carboni, S.; Cinausero, M.; Chbihi, A.; Chiari, M.; Corsi, A.; Crespi, F. C. L.; D'Agostino, M.; Degerlier, M.; Fornal, B.; Giaz, A.; Gramegna, F.; Krzysiek, M.; Leoni, S.; Marchi, T.; Matejska-Minda, M.; Mazumdar, I.; Meczyński, W.; Million, B.; Montanari, D.; Morelli, L.; Myalski, S.; Nannini, A.; Nicolini, R.; Pasquali, G.; Piantelli, S.; Prete, G.; Roberts, O. J.; Schmitt, Ch.; Styczeń, J.; Szpak, B.; Valdré, S.; Wasilewska, B.; Wieland, O.; Wieleczko, J. P.; Ziebliński, M.; Dudek, J.; Dinh Dang, N.
2015-05-01
High-energy giant dipole resonance (GDR) γ rays were measured following the decay of the hot, rotating compound nucleus of 88Mo, produced at excitation energies of 124 and 261 MeV. The reaction 48Ti + 40Ca at 300 and 600 MeV bombarding energies has been used. The data were analyzed using the statistical model Monte Carlo code gemini++. It allowed extracting the giant dipole resonance parameters by fitting the high-energy γ -ray spectra. The extracted GDR widths were compared with the available data at lower excitation energy and with theoretical predictions based on (i) The Lublin-Strasbourg drop macroscopic model, supplemented with thermal shape fluctuations analysis, and (ii) The phonon damping model. The theoretical predictions were convoluted with the population matrices of evaporated nuclei from the statistical model gemini++. Also a comparison with the results of a phenomenological expression based on the existing systematics, mainly for lower temperature data, is presented and discussed. A possible onset of a saturation of the GDR width was observed around T =3 MeV.
Nature of the pygmy dipole resonance in 140Ce studied in (alpha, alpha' gamma) experiments.
Savran, D; Babilon, M; van den Berg, A M; Harakeh, M N; Hasper, J; Matic, A; Wörtche, H J; Zilges, A
2006-10-27
A concentration of electric-dipole excitations below the particle threshold, which is frequently denoted as the pygmy dipole resonance, has been studied in the semimagic nucleus 140Ce in (alpha, alpha' gamma) experiments at E alpha = 136 MeV. The technique of alpha-gamma coincidence experiments allows the separation of E1 excitations from states of other multipolarities in the same energy region and provides an excellent energy resolution to allow a detailed analysis for each state. The experimental results show that the PDR splits into two parts with different nuclear structure: one part which is excited in (alpha, alpha' gamma) as well as (gamma, gamma') experiments and one part which is excited only in (gamma, gamma').
Effect of angular momentum on giant dipole resonance observables in the 28Si+116Cd reaction
NASA Astrophysics Data System (ADS)
Mukul, Ish; Roy, A.; Sugathan, P.; Gehlot, J.; Mohanto, G.; Madhavan, N.; Nath, S.; Dubey, R.; Mazumdar, I.; Gothe, D. A.; Kaur, Maninder; Kumar, A. K. Rhine; Arumugam, P.
2013-08-01
Background: Giant dipole resonance (GDR) has been used as an important tool for studying nuclear properties in hot rotating nuclei. Exclusive measurements using low-energy γ-ray multiplicity filters provide more control over angular momentum selection in such measurements.Purpose: Study the effect of angular momentum and temperature on nuclear deformations and GDR widths at high excitation energies in 144Sm.Methods: Exclusive measurements of GDR γ rays were carried out in the 28Si+116Cd reaction populated at two different excitation energies. Beam energies of 125 and 140 MeV pumped the nuclei to average temperatures
NASA Astrophysics Data System (ADS)
Huang, Dao-Ling; Liu, Hong-Tao; Ning, Chuan-Gang; Dau, Phuong Diem; Wang, Lai-Sheng
2017-01-01
We report both non-resonant and resonant high-resolution photoelectron imaging of cryogenically-cooled deprotonated uracil anions, N1[U-H]-, via vibrational levels of a dipole-bound excited state. Photodetachment spectroscopy of N1[U-H]- was reported previously (Liu et al., 2014), in which forty-six vibrational autodetachment resonances due to the excited dipole-bound state were observed. By tuning the detachment laser to the vibrational levels of the dipole-bound state, we obtained high-resolution resonant photoelectron spectra, which are highly non-Franck-Condon. The resonant photoelectron spectra reveal many Franck-Condon inactive vibrational modes, significantly expanding the capability of photoelectron spectroscopy. A total of twenty one fundamental vibrational frequencies for the N1[U-H]rad radical are obtained, including all eight low-frequency out-of-plane modes, which are forbidden in non-resonant photoelectron spectroscopy. Furthermore, the breakdown of the Δv = -1 propensity rule is observed for autodetachment from many vibrational levels of the dipole-bound state, due to anharmonic effects. In particular, we have observed intramolecular electron rescattering in a number of resonant photoelectron spectra, leading to excitations of low-frequency vibrational modes. Further theoretical study may be warranted, in light of the extensive experimental data and new observations, to provide further insight into the autodetachment dynamics and vibronic coupling in dipole-bound states, as well as electron molecule interactions.
Extra γ-ray strength for 116,117Sn arising from pygmy dipole resonance
NASA Astrophysics Data System (ADS)
Kamata, M.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Itoh, O.; Iwamoto, C.; Kondo, T.; Toyokawa, H.; Lui, Y.-W.; Goriely, S.
2010-06-01
Photoneutron cross sections were measured for 117Sn and 116Sn near neutron thresholds with quasi-monochromatic laser Compton scattering γ-rays. The measured cross sections for 117Sn and 116Sn are strongly enhanced from the threshold behavior expected for L = 1 neutron emissions after E1 photoexcitation. This suggests the presence of extra γ-ray strength in the low-energy tail of the giant dipole resonance. The present cross sections were analyzed together with radiative neutron capture cross sections for 116Sn within the framework of the statistical model calculation. It is shown that the extra γ-ray strength can be interpreted as pygmy E1 resonance which was previously reported in the nuclear resonance fluorescence experiment for 116Sn and 124Sn.
Extra gamma-ray strength for {sup 116,117}Sn arising from pygmy dipole resonance
Kamata, M.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Itoh, O.; Iwamoto, C.; Kondo, T.; Toyokawa, H.; Lui, Y.-W.; Goriely, S.
2010-06-01
Photoneutron cross sections were measured for {sup 117}Sn and {sup 116}Sn near neutron thresholds with quasi-monochromatic laser Compton scattering gamma-rays. The measured cross sections for {sup 117}Sn and {sup 116}Sn are strongly enhanced from the threshold behavior expected for L = 1 neutron emissions after E1 photoexcitation. This suggests the presence of extra gamma-ray strength in the low-energy tail of the giant dipole resonance. The present cross sections were analyzed together with radiative neutron capture cross sections for {sup 116}Sn within the framework of the statistical model calculation. It is shown that the extra gamma-ray strength can be interpreted as pygmy E1 resonance which was previously reported in the nuclear resonance fluorescence experiment for {sup 116}Sn and {sup 124}Sn.
The pygmy dipole resonance in 68Ni and the neutron skin
NASA Astrophysics Data System (ADS)
Wieland, O.; Bracco, A.
2011-04-01
A search of the pygmy resonance in 68Ni was made using the virtual photon technique. The experiment was carried out using the radioactive beam 68Ni at 600 A MeV, produced with fragmentation of 86Kr at 900 A MeV on a 9Be target. The 68Ni beam was separated by a fragment separator, and the γ-rays produced at the interaction with the Au target were detected with the RISING and FRS set-up at the GSI laboratory in Germany, also including the HECTOR array. The measured γ-ray spectra show a peak centered at approximately 11 MeV, whose intensity can be explained in term of an enhanced strength of the dipole response function (pygmy resonance). A pygmy structure of this type was also predicted by different models for this unstable neutron-rich nucleus. Correlations between the behavior of the nuclear symmetry energy, the neutron skins, and the percentage of energy-weighted sum rule (EWSR) exhausted by the pygmy dipole resonance (PDR) are investigated by using different random phase approximation (RPA) models.
Jia, Hongwei; Liu, Haitao; Zhong, Ying
2015-01-01
The radiation of an electric dipole emitter can be drastically enhanced if the emitter is placed in the nano-gap of a metallic dipole antenna. By assuming that only surface plasmon polaritons (SPPs) are excited on the antenna, we build up an intuitive pure-SPP model that is able to comprehensively predict the electromagnetic features of the antenna radiation, such as the total or radiative emission rate and the far-field radiation pattern. With the model we can distinguish the respective contributions from SPPs and from other surface waves to the antenna radiation. It is found that for antennas with long arms that support higher-order resonances, SPPs provide a dominant contribution to the antenna radiation, while for other cases, the contribution of surface waves other than SPPs should be considered. The model reveals an intuitive picture that the enhancement of the antenna radiation is due to surface waves that are resonantly excited on the two antenna arms and that are further coupled into the nano-gap or scattered into free space. From the model we can derive a phase-matching condition that predicts the antenna resonance and the resultant enhanced radiation. The model is helpful for a physical understanding and intuitive design of antenna devices. PMID:25678191
Jia, Hongwei; Liu, Haitao; Zhong, Ying
2015-02-13
The radiation of an electric dipole emitter can be drastically enhanced if the emitter is placed in the nano-gap of a metallic dipole antenna. By assuming that only surface plasmon polaritons (SPPs) are excited on the antenna, we build up an intuitive pure-SPP model that is able to comprehensively predict the electromagnetic features of the antenna radiation, such as the total or radiative emission rate and the far-field radiation pattern. With the model we can distinguish the respective contributions from SPPs and from other surface waves to the antenna radiation. It is found that for antennas with long arms that support higher-order resonances, SPPs provide a dominant contribution to the antenna radiation, while for other cases, the contribution of surface waves other than SPPs should be considered. The model reveals an intuitive picture that the enhancement of the antenna radiation is due to surface waves that are resonantly excited on the two antenna arms and that are further coupled into the nano-gap or scattered into free space. From the model we can derive a phase-matching condition that predicts the antenna resonance and the resultant enhanced radiation. The model is helpful for a physical understanding and intuitive design of antenna devices.
Nucleon-nucleon symmetry potential term and giant dipole resonance {gamma}-ray emission
Giuliani, G.; Papa, M.
2006-03-15
A study of the dependence of the giant dipole resonance {gamma}-ray yield from different functional forms of the symmetry term for the nucleon-nucleon interaction potential has been performed through the semiclassical molecular dynamics approach CoMD-II. We studied central and midperipheral reactions in the charge/mass asymmetric system {sup 40}Ca+{sup 48}Ca at 45 MeV/nucleon. The calculations show that the balance between the dynamical and the statistical emission is very sensitive to the 'stiffness' of the symmetry term. This sensitivity could be highlighted by measuring the degree of coherence and the anisotropy ratio related to the dynamically emitted radiation.
Shimada, Rintaro; Hamaguchi, Hiro-o
2014-05-28
We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-β-carotene (β-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute β-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of β-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of β-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of β-carotene with the vibrations of a proximate solvent molecule through solute-solvent dipole-dipole and dipole-quadrupole interactions. It is shown that the infrared active modes arise from the dipole-dipole interaction, whereas Raman active modes from the dipole-quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å.
NASA Astrophysics Data System (ADS)
Shimada, Rintaro; Hamaguchi, Hiro-o.
2014-05-01
We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-β-carotene (β-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute β-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of β-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of β-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of β-carotene with the vibrations of a proximate solvent molecule through solute-solvent dipole-dipole and dipole-quadrupole interactions. It is shown that the infrared active modes arise from the dipole-dipole interaction, whereas Raman active modes from the dipole-quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å.
Inhomogeneous and intrinsic damping of giant dipole resonance in hot rotating nuclei with A ~ 150
NASA Astrophysics Data System (ADS)
Chakrabarty, D. R.; Datar, V. M.; Kumar, Suresh; Mirgule, E. T.; Mitra, A.; Nanal, V.; Pillay, R. G.; Rout, P. C.
2010-05-01
High-energy gamma rays in the range of ~4-28 MeV were measured in the reaction 28Si+124Sn at E(28Si) ~ 185 MeV in coincidence with low-energy gamma ray multiplicities and evaporation residues. The centroid energy and width of the giant dipole resonance were extracted for various multiplicity windows from the statistical model analysis. These extracted widths, along with those from an earlier measurement at E(28Si) ~ 149 MeV, show a discrepancy with the results of a calculation under the thermal shape fluctuation model which describes the inhomogeneous damping of the resonance. An empirical form of the temperature and angular momentum dependence of the width, describing the data at both the beam energies, has been derived. The present results suggest that the contributions from both the inhomogeneous damping and the intrinsic collisional damping processes should be included.
Development of the new gamma-ray calorimeter for the measurement of Pigmy Dipole Resonance
NASA Astrophysics Data System (ADS)
Shikata, Mizuki; Nakamura, Takashi; Togano, Yasuhiro; Kondo, Yosuke
2014-09-01
A new γ-ray calorimeter CATANA (CAlorimeter for gamma γ-ray Transition in Atomic Nuclei at high isospin Asynmetry) has been developed to measure highly excited states like the pygmy dipole resonance and the giant dipole resonance. CATANA will be used with the SAMURAI spectrometer at RIBF. The excitation energy spectrum will be reconstructed combining the invariant mass of the reaction products measured by SAMURAI and γ-ray energies from CATANA. CATANA has focused on achieving a high detection efficiency. It is calculated as 56% for 1 MeV γ-rays from beam with a velocity of β = 0.6. The CATANA array consists of 200 CsI(Na) crystals and covers angles from 10 to 120 degrees along the beam axis. In this study, we have tested prototype crystals of CATANA to evaluate their performance. A position dependence of the light input have been measured and compared with a Monte-Carlo simulation based on GEANT4. In this talk, we will report the design of CATANA and the result of the tests and the simulation.
Measurement of the magnetic-field parameters of the NICA Booster dipole magnet
NASA Astrophysics Data System (ADS)
Kostromin, S. A.; Borisov, V. V.; Bichkov, A. V.; Golubitsky, O. M.; Donyagin, A. N.; Morozov, N. A.; Samsonov, E. V.; Omelyanenko, M. M.; Khodzhibagiyan, H. G.; Shemchuk, A. V.
2016-12-01
Serial assembly and tests of dipole and quadrupole magnets of the NICA Booster have started at the Laboratory of High Energy Physics of the Joint Institute for Nuclear Research (JINR). The accelerator is fitted with Nuclotron-type magnets with a superconducting winding and an iron yoke for shaping the needed magnetic field. The design of magnets for NICA was optimized (based on the experience gained in constructing and operating the JINR Nuclotron) for the production of magnetic fields of the required configuration in terms of the beam dynamics in the accelerator and the collider. Measurements of parameters of the field of each magnet are expected to be performed in the process of assembly and testing of each module of the magnet-cryostat system of the NICA Booster and Collider. The results of magnetic measurements for the NICA Booster dipole magnet are presented.
Resonance Parameter Adjustment Based on Integral Experiments
Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; Forget, Benoit
2016-06-02
Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.
Resonance Parameter Adjustment Based on Integral Experiments
Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; ...
2016-06-02
Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, suchmore » as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.« less
Resonance Parameter Adjustment Based on Integral Experiments
Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; Forget, Benoit
2016-06-02
Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.
Neutron-skin thickness from the study of the anti-analog giant dipole resonance
Krasznahorkay, A.; Stuhl, L.; Csatlos, M.; Algora, A.; and others
2012-10-20
The {gamma}-decay of the anti-analog of the giant dipole resonance (AGDR) to the isobaric analog state has been measured following the p({sup 124}Sn,n) reaction at a beam energy of 600 MeV/nucleon. The energy of the transition was also calculated with state-of-the-art self-consistent relativistic random-phase approximation (RPA) and turned out to be very sensitive to the neutronskin thickness ({Delta}R{sub pn}). By comparing the theoretical results with the measured one, the {Delta}R{sub pn} value for {sup 124}Sn was deduced to be 0.21 {+-} 0.07 fm, which agrees well with the previous results. The present method offers new possibilities for measuring the neutron-skin thicknesses of very exotic isotopes.
Nuclear spin cooling by electric dipole spin resonance and coherent population trapping
NASA Astrophysics Data System (ADS)
Li, Ai-Xian; Duan, Su-Qing; Zhang, Wei
2017-09-01
Nuclear spin fluctuation suppression is a key issue in preserving electron coherence for quantum information/computation. We propose an efficient way of nuclear spin cooling in semiconductor quantum dots (QDs) by the coherent population trapping (CPT) and the electric dipole spin resonance (EDSR) induced by optical fields and ac electric fields. The EDSR can enhance the spin flip-flop rate and may bring out bistability under certain conditions. By tuning the optical fields, we can avoid the EDSR induced bistability and obtain highly polarized nuclear spin state, which results in long electron coherence time. With the help of CPT and EDSR, an enhancement of 1500 times of the electron coherence time can been obtained after a 500 ns preparation time.
Search for the Pygmy Dipole Resonance in Ni68 at 600MeV/nucleon
NASA Astrophysics Data System (ADS)
Wieland, O.; Bracco, A.; Camera, F.; Benzoni, G.; Blasi, N.; Brambilla, S.; Crespi, F. C. L.; Leoni, S.; Million, B.; Nicolini, R.; Maj, A.; Bednarczyk, P.; Grebosz, J.; Kmiecik, M.; Meczynski, W.; Styczen, J.; Aumann, T.; Banu, A.; Beck, T.; Becker, F.; Caceres, L.; Doornenbal, P.; Emling, H.; Gerl, J.; Geissel, H.; Gorska, M.; Kavatsyuk, O.; Kavatsyuk, M.; Kojouharov, I.; Kurz, N.; Lozeva, R.; Saito, N.; Saito, T.; Schaffner, H.; Wollersheim, H. J.; Jolie, J.; Reiter, P.; Warr, N.; Deangelis, G.; Gadea, A.; Napoli, D.; Lenzi, S.; Lunardi, S.; Balabanski, D.; Lobianco, G.; Petrache, C.; Saltarelli, A.; Castoldi, M.; Zucchiatti, A.; Walker, J.; Bürger, A.
2009-03-01
The γ decay from Coulomb excitation of Ni68 at 600MeV/nucleon on a Au target was measured using the RISING setup at the fragment separator of GSI. The Ni68 beam was produced by a fragmentation reaction of Kr86 at 900MeV/nucleon on a Be9 target and selected by the fragment separator. The γ rays produced at the Au target were measured with HPGe detectors at forward angles and with BaF2 scintillators at backward angles. The measured spectra show a peak centered at approximately 11 MeV, whose intensity can be explained in terms of an enhanced strength of the dipole response function (pygmy resonance). Such pygmy structure has been predicted in this unstable neutron-rich nucleus by theory.
Proton decay from the isoscalar giant dipole resonance in {sup 58}Ni
Hunyadi, M.; Hashimoto, H.; Fujimura, H.; Fujiwara, M.; Hara, K.; Itoh, M.; Nakanishi, K.; Okumura, S.; Li, T.; Garg, U.; Hoffman, J.; Nayak, B. K.; Akimune, H.; Gacsi, Z.; Harakeh, M. N.
2009-10-15
Proton decay from the 3({Dirac_h}/2{pi}){omega} isoscalar giant dipole resonance (ISGDR) in {sup 58}Ni has been measured using the ({alpha},{alpha}{sup '}p) reaction at a bombarding energy of 386 MeV to investigate its decay properties. We have extracted the ISGDR strength under the coincidence condition between inelastically scattered {alpha} particles at forward angles and decay protons emitted at backward angles. Branching ratios for proton decay to low-lying states of {sup 57}Co have been determined, and the results compared with predictions of recent continuum-RPA calculations. The final-state spectra of protons decaying to the low-lying states in {sup 57}Co were analyzed for a more detailed understanding of the structure of the ISGDR. It is found that there are differences in the structure of the ISGDR as a function of excitation energy.
Giant dipole resonance and shape transitions in hot and rotating 88Mo
NASA Astrophysics Data System (ADS)
Rhine Kumar, A. K.; Arumugam, P.; Dang, N. Dinh; Mazumdar, I.
2017-08-01
The giant dipole resonance (GDR) observables are calculated within the thermal shape fluctuation model by considering the probability distributions of different angular momentum (I ) and temperature (T ) values estimated recently in the deexcitation process of the compound nucleus 88Mo. These results are found to be very similar to the results obtained with the average T (Tave) and average I (Iave) corresponding to those distributions. The shape transitions in 88Mo at different T and I are also studied through the free energy surfaces calculated within the microscopic-macroscopic approach. The deformation of 88Mo is found to increase considerably with T and I , leading to the Jacobi shape transition at I ˜50 ℏ . The combined effect of increasing deformation, larger fluctuations at higher T , and larger Coriolis splitting of GDR components at higher I , leads to a rapid increase in the GDR width.
Isovector dipole resonance and shear viscosity in low energy heavy-ion collisions
NASA Astrophysics Data System (ADS)
Guo, C. Q.; Ma, Y. G.; He, W. B.; Cao, X. G.; Fang, D. Q.; Deng, X. G.; Zhou, C. L.
2017-05-01
The ratio of shear viscosity over entropy density in low energy heavy-ion collision has been calculated by using the Green-Kubo method in the framework of an extended quantum molecular dynamics model. After the system almost reaches a local equilibration for a head-on 40Ca+100Mo collision, thermodynamic and transport properties are extracted. Meanwhile, the isovector giant dipole resonance (IVGDR) of the collision system also is studied. By the Gaussian fits to the IVGDR photon spectra, the peak energies of the IVGDR are extracted at different incident energies. The result shows that the IVGDR peak energy has a positive correlation with the ratio of shear viscosity over entropy density. This is a quantum effect and indicates a difference between nuclear matter and classical fluid.
NASA Astrophysics Data System (ADS)
Silenko, Alexander J.
2017-05-01
A general theoretical description of a magnetic resonance is presented. This description is necessary for a detailed analysis of spin dynamics in electric-dipole-moment experiments in storage rings. General formulas describing a behavior of all components of the polarization vector at the magnetic resonance are obtained for an arbitrary initial polarization. These formulas are exact on condition that the nonresonance rotating field is neglected. The spin dynamics is also calculated at frequencies far from resonance with allowance for both rotating fields. A general quantum-mechanical analysis of the spin evolution at the magnetic resonance is fulfilled and the full agreement between the classical and quantum-mechanical approaches is shown. Quasimagnetic resonances for particles and nuclei moving in noncontinuous perturbing fields of accelerators and storage rings are considered. Distinguishing features of quasimagnetic resonances in storage ring electric-dipole-moment experiments are investigated in detail. The exact formulas for the effect caused by the electric dipole moment are derived. The difference between the resonance effects conditioned by the rf electric-field flipper and the rf Wien filter is found and is calculated for the first time. The existence of this difference is crucial for the establishment of a consent between analytical derivations and computer simulations and for checking spin tracking programs. The main systematical errors are considered.
Rho resonance parameters from lattice QCD
Guo, Dehua; Alexandru, Andrei; Molina, Raquel; Döring, Michael
2016-08-01
We perform a high-precision calculation of the phase shifts for $\\pi$-$\\pi$ scattering in the I = 1, J = 1 channel in the elastic region using elongated lattices with two mass-degenerate quark favors ($N_f = 2$). We extract the $\\rho$ resonance parameters using a Breit-Wigner fit at two different quark masses, corresponding to $m_{\\pi} = 226$MeV and $m_{\\pi} = 315$MeV, and perform an extrapolation to the physical point. The extrapolation is based on a unitarized chiral perturbation theory model that describes well the phase-shifts around the resonance for both quark masses. We find that the extrapolated value, $m_{\\rho} = 720(1)(15)$MeV, is significantly lower that the physical rho mass and we argue that this shift could be due to the absence of the strange quark in our calculation.
Double Photon Decay of the Electromagnetically Excited Double Giant Dipole Resonance in LEAD-208
NASA Astrophysics Data System (ADS)
Ritman, James Lambrecht
In this work the electromagnetic excitation of high lying collective states has been studied in relativistic heavy ion collisions. The interaction in peripheral collisions is dominated by the exchange of high energy virtual photons. Heavy systems near 1cdotA GeV produce a virtual photon field that is highly luminous and of sufficiently short duration to enable the multiple excitation of Giant Resonances with high probability. In particular, the double excitation of the Giant Dipole Resonance (GDR) has been studied in this work by measuring the photons emitted in peripheral reactions with the system 1.A GeV ^ {209}Bi on ^{208} Pb. This study concentrated on the photon decay of Coulomb excited collective states. Despite the relatively small ground state gamma-decay branching ratio, investigation of this channel provides several advantages compared to measuring statistical particle decay. The most important advantage is the strong enhancement of E1 transitions with respect to higher multipolarities; therefore, study of gamma-decay provides a highly selective measurement of the GDR. Photons in the Giant Resonance region were measured both as singles and as gamma- gamma pairs. For symmetry reasons the target and projectile nuclei can be mutually Coulomb excited. In order to insure that both photons in the gamma -gamma pairs came from the same nucleus, the large Doppler shift of photons emitted from the moving projectile has been exploited. Appropriate placement of the gamma detectors permitted a complete separation of the GDR photons emitted by either the target or projectile nucleus. This work provides the first experimental evidence of the gamma-gamma decay of the Coulomb excited double GDR (GDR2). The position of the resonance indicates harmonicity of the T_{<} multi-GDR. However, the increase of the GDR2 width over the GDR's width by only about a factor of sqrt{2} is significantly less than expected. Finally, the GDR2 excitation cross section is compared with model
Charged-particle Decay of the Isoscalar giant dipole resonance in ^58Ni
NASA Astrophysics Data System (ADS)
Li, Tao; Hunyadi, Matyas; Garg, Umesh; Hoffman, Joe; Nayak, B. K.; Fujiwara, M.; Hara, K.; Hashimoto, H.; Itoh, M.; Murakami, T.; Nakanishi, K.; Kishi, S.; Sakaguchi, H.; Terashima, S.; Uchida, M.; Yasuda, Y.; Yosoi, M.; Akimune, H.; Harakeh, M. N.
2004-10-01
The isoscalar giant dipole resonance(ISGDR) has been measured by single experiments with the use of inelastic α-scattering in many nuclei[1]. However, information on its decay properties is scarce. The decay properties, especially the relative population and total strength of hole states in the (A-1) nucleus resulting from particle decay of giant resonance in nuclei can provide crucial tests for the microscopic model calculations. Caculations based on continuum-RPA approach have recently become abailable and provide results on partial branching ratios for direct neutron and proton decay of ISGDR [2]. We report on a coincidence experiment searching for these direct particle decay branches from the ISGDR in the nucleus ^58Ni. The experiment was performed at the RCNP, Osaka University, using inelastic α-scattering at a beam energy of 400 MeV. The inelastically scattered α particles were detected by the magnetic spectrometer ``Grand Raiden'' at 2.5^rc, with the decay protons detected by a set of sixteen Si(Li) detectors with a thickness of 5.0 mm and an effective area of 400 mm^2 each placed at backward angles. The result for the observed final states in ^57Co will be presented and compared with the theoretical calculations. References: [1] M.Uchida et al., Phys.Rev. C 69, 051301 (2004), [2] M.L. Gorelik et al., Phys. Rev. C 69, 054322 (2004)
Resonance parameter measurements and analysis of gadolinium
Leinweber, G.; Barry, D. P.; Trbovich, M. J.; Burke, J. A.; Drindak, N. J.; Knox, H. D.; Ballad, R. V.; Block, R. C.; Danon, Y.; Severnyak, L. I.
2006-07-01
The purpose of the present work is to measure the neutron cross sections of gadolinium accurately. Gd has the highest thermal absorption cross section of any natural element. Therefore it is an important element for thermal reactor applications Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Inst. (RPI) LINAC facility using metallic and liquid Gd samples. The liquid samples were isotopically-enriched in either {sup 155}Gd or {sup 157}Gd. The capture measurements were made at the 25-m flight station with a sodium iodide detector, and the transmission measurements were performed at 15- and 25-m flight stations with {sup 6}Li glass scintillation detectors. The multilevel R-matrix Bayesian code SAMMY was used to extract resonance parameters. The results of the thermal region analysis are significant. Resonance parameters for the low energy doublet, at 0.025 and 0.032 eV, are presented. The thermal (2200 m/s) capture cross section of {sup 157}Gd has been measured to be 11% smaller than that calculated from ENDF/B-VI updated through release 8. Thermal capture cross sections and capture resonance integrals for each isotope as well as elemental gadolinium are presented. In the epithermal region, natural metal samples were measured in capture and transmission. Neutron interaction data up to 300 eV have been analyzed. Substantial improvement to the understanding of gadolinium cross sections is presented, particularly above 180 eV where the ENDF resolved region for {sup 155}Gd ends. (authors)
Liu, Bo; Tang, Chaojun; Chen, Jing; Wang, Qiugu; Pei, Mingxu; Tang, Huang
2017-05-15
It is well known that the absorption efficiency of a suspended monolayer graphene in the optical wavelength rang is only 2.3%, which limits its optoelectronic applications. In this work, we numerically demonstrate dual-band absorption enhancement of monolayer graphene at optical frequency, with the maximum absorption efficiency reaching to about 70% under optimum conditions. The dual-band absorption enhancement arises from the excitations of surface plasmon polaritons and magnetic dipole resonances in metamaterials. The monolayer graphene is sandwiched between a periodic array of Ag nanodisks and a SiO2 spacer supported on an Ag substrate. The resonance wavelengths of two absorption bands arising from surface plasmon polaritons and magnetic dipole resonances can be easily tuned by the array period and the diameter of the Ag nanodisks, respectively. Our designed graphene light absorber may find some potential applications in optoelectronic devices, such as photodetectors.
Wieland, O; Bracco, A; Camera, F; Benzoni, G; Blasi, N; Brambilla, S; Crespi, F; Giussani, A; Leoni, S; Million, B; Moroni, A; Barlini, S; Kravchuk, V L; Gramegna, F; Lanchais, A; Mastinu, P; Maj, A; Brekiesz, M; Kmiecik, M; Bruno, M; Geraci, E; Vannini, G; Casini, G; Chiari, M; Nannini, A; Ordine, A; Ormand, W E
2006-06-16
The {gamma} decay of the Giant Dipole Resonance in the {sup 132}Ce compound nucleus with temperature up to {approx} 4 MeV has been measured. The symmetric {sup 64}Ni + {sup 68}Zn at E{sub beam} = 300, 400, 500 MeV and the asymmetric reaction {sup 16}O + {sup 116}Sn at E{sub beam} = 130, 250 MeV have been investigated. Light charged particles and {gamma} rays have been detected in coincidence with the recoiling compound system. In the case of the mass symmetric {sup 64}Ni induced reaction the {gamma} and charged particle spectral shapes are found to be consistent with the emission from a fully equilibrated compound nuclei and the GDR parameters are extracted from the data using a statistical model analysis. The GDR width is found to increase almost linear with temperature. This increase is rather well reproduced within a model which includes both the thermal fluctuation of the nuclear shape and the lifetime of the compound nucleus.
Slabko, V V; Tsipotan, A S; Aleksandrovsky, A S
2013-05-31
The influence of the oscillation phases of the dipole moments induced in metal nanoparticles and quantum dots by an external laser field on their interaction energy is considered. It is shown that a difference in resonant frequencies leads to the formation of additional minima and maxima, which are absent in the spectral dependence of the interaction energy of identical particles at similar orientations of the pair of particles with respect to the plane of polarisation of radiation. These features are due to the fact that the oscillation phase difference of the induced dipole moments of particles reaches values close to {pi}. (interaction of laser radiation with matter. laser plasma)
Temperature dependence of quantal and thermal dampings of the hot giant dipole resonance
NASA Astrophysics Data System (ADS)
Nguyen, Dinh Dang; Arima, Akito
1998-07-01
A systematic study of the damping of the giant dipole resonance (GDR) in 90Zr, 120Sn and 208Pb as a function of temperature T is performed. The double-time Green function technique is employed to determine the single-particle and GDR dampings. The single-particle energies, obtained in the Woods-Saxon potential for these nuclei, are used in the calculations. The results show that the coupling of collective vibration to the pp and hh excitations, which causes the thermal damping width, is responsible for the enlargement of the total width with increasing temperature up to T ≈ 3MeV and its saturation at higher temperatures. The quantal width, which arises from the coupling of the collective mode to the ph excitations decreases slowly with increasing temperature. The effect of single-particle damping on the GDR width is small. The results are found in an overall agreement with the experimental data for the GDR width, obtained in the inelastic α scattering and heavy-ion fusion reactions at excitation energies E* ⩽ 450 MeV. At high excitation energies (E* > 400 MeV) a behavior similar to the transition from zero to ordinary sounds is observed.
Contribution of higher-order processes to the damping of hot giant dipole resonance
NASA Astrophysics Data System (ADS)
Dinh Dang, Nguyen; Tanabe, Kosai; Arima, Akito
1998-12-01
A systematic study is presented for three characteristics of the giant dipole resonance (GDR): (i) its width, (ii) its shape, and (iii) the integrated yield of emitted γ rays in 120Sn and 208Pb as a function of temperature T. The double-time Green's function method has been used to derive a complete set of equations, which allow one to calculate explicitly the GDR width due to coupling to all forward-going processes up to two-phonon ones at most in the second order of the interaction strength. The numerical calculations have been performed using the single-particle energies defined from the Woods-Saxon potentials. An overall agreement between theory and experiment is found for all three characteristics. The results show that the total width of the GDR due to coupling of the GDR phonon to all ph, pp, and hh configurations increases sharply at low temperatures up to T~ 3 MeV and saturates at T~4-6 MeV. The quantal width ΓQ due to coupling to ph configurations decreases slowly with increasing T. It becomes almost independent of T only when the contribution of two-phonon processes at T≠0 is omitted. The observed saturation of the integrated yield above E*~300 MeV is reproduced in both the GDR region and the region above it.
The temperature dependence of the width of the giant dipole resonance
Ormand, W.E. |; Bortignon, P.F. |; Broglia, R.A. ||
1995-12-31
A systematic study of the full-width-at-half-maximum (FWHM) of the giant-dipole resonance (GDR) as a function of temperature for the nuclei {sup 120}Sn and {sup 208}Pb confirms the overall theoretical picture of the GDR in hot nuclei; in particular, the role played by large-amplitude thermal fluctuations of the nuclear shape. This is confirmed by the good agreement between theory and experiment achieved over a range of temperatures from 1.25--32 MeV and by the differences in the behavior of the FWHM for {sup 120}Sn and {sup 208}Pb, which can be attributed to the presence of strong shell corrections favoring spherical shapes in {sup 208}Pb that are absent in {sup 120}Sn. Finally, the increase in the FWHM over that expected from thermal averaging at temperatures of the order 3.0 MeV is in accordance with the increase expected from the particle evaporation of the compound system.
Extreme nuclear shapes examined via giant dipole resonance lineshapes in hot light-mass systems
Pandit, Deepak; Mukhopadhyay, S.; Pal, Surajit; Bhattacharya, S.; Bhattacharya, C.; Banerjee, K.; Kundu, S.; Rana, T. K.; Dey, A.; Mukherjee, G.; Ghosh, T.; Banerjee, S. R.; De, A.; Gupta, D.
2010-06-15
The influence of alpha clustering on nuclear reaction dynamics is investigated using the giant dipole resonance (GDR) lineshape studies in the reactions {sup 20}Ne (E{sub lab}=145,160 MeV) + {sup 12}C and {sup 20}Ne (E{sub lab}=160 MeV) + {sup 27}Al, populating {sup 32}S and {sup 47}V, respectively. The GDR lineshapes from the two systems are remarkably different from each other. Whereas, the non-alpha-like {sup 47}V undergoes Jacobi shape transition and matches exceptionally well with the theoretical GDR lineshape estimated under the framework rotating liquid drop model (RLDM) and thermal shape fluctuation model (TSFM) signifying shape equilibration, for the alpha cluster {sup 32}S an extended prolate kind of shape is observed. This unusual deformation, seen directly via gamma decay for the first time, is predicted to be due to the formation of orbiting dinuclear configuration or molecular structure of {sup 16}O + {sup 16}O in the {sup 32}S superdeformed band.
Giant dipole resonance width in nuclei near Sn at low temperature and high angular momentum
Bhattacharya, Srijit; Mukhopadhyay, S.; Pandit, Deepak; Pal, Surajit; Bhattacharya, S.; Bhattacharya, C.; Banerjee, K.; Kundu, S.; Rana, T. K.; Dey, A.; Mukherjee, G.; Ghosh, T.; Gupta, D.; Banerjee, S. R.
2008-02-15
High energy {gamma} rays in coincidence with low energy yrast {gamma} rays have been measured from {sup 113}Sb, at excitation energies of 109 and 122 MeV, formed by bombarding {sup 20}Ne on {sup 93}Nb at projectile energies of 145 and 160 MeV, respectively, to study the role of angular momentum (J) and temperature (T) over giant dipole resonance (GDR) width ({gamma}). The maximum populated angular momenta for fusion were 67({Dirac_h}/2{pi}) and 73({Dirac_h}/2{pi}), respectively, for the above-mentioned beam energies. The high energy photons were detected using a Large Area Modular BaF{sub 2} Detector Array (LAMBDA) along with a 24-element multiplicity filter. After pre-equilibrium corrections, the excitation energy E* was averaged over the decay steps of the compound nucleus (CN). The average values of temperature, angular momentum, CN mass, etc., have been calculated using the statistical model code CASCADE. Using those average values, results show the systematic increase of GDR width with T, which is consistent with Kusnezov parametrization and the thermal shape fluctuation model (TSFM). The rise of GDR width with temperature also supports the assumptions of adiabatic coupling in the TSFM. But the GDR widths and corresponding reduced plots with J are not consistent with those of the theoretical model at high spins.
Electric dipole spin resonance in systems with a valley-dependent g factor
NASA Astrophysics Data System (ADS)
Rančić, Marko J.; Burkard, Guido
2016-05-01
In this theoretical study we qualitatively and quantitatively investigate the electric dipole spin resonance (EDSR) in a single Si/SiGe quantum dot in the presence of a magnetic field gradient, e.g., produced by a ferromagnet. We model a situation in which the control of electron spin states is achieved by applying an oscillatory electric field, inducing real-space oscillations of the electron inside the quantum dot. One of the goals of our study is to present a microscopic theory of valley-dependent g factors in Si/SiGe quantum dots and investigate how valley relaxation combined with a valley-dependent g factor leads to a novel electron spin dephasing mechanism. Furthermore, we discuss the interplay of spin and valley relaxations in Si/SiGe quantum dots. Our findings suggest that the electron spin dephases due to valley relaxation, and are in agreement with recent experimental studies [Nat. Nanotechnol. 9, 666 (2014), 10.1038/nnano.2014.153].
Isovector dipole resonances in {sup 4}He and neutrino-heating in supernova
Nakayama, S.; Matsumoto, E.; Fushimi, K.; Hayami, R.; Suzuki, T.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Fujiwara, M.; Hashimoto, H.; Kawase, K.; Nakanishi, K.; Oota, T.; Yosoi, M.; Greenfield, M. B.; Kudoh, T.; Sagara, K.; Tanaka, M.
2010-06-01
We studied transition strengths to isovector dipole resonances (GDR-1-bar , SDR-1-bar , and SDR-2-bar ) in {sup 4}He by using the {sup 4}He({sup 7}Li,{sup 7}Begamma) reaction at 455 MeV and by comparing with shell-model calculations, in order to estimate cross sections of {sup 4}He for reactions induced by neutrinos emitting from a thermalized neutrino-sphere in the type-II supernova. Excitation of the SDR was dominant in the neutrino-heating of {sup 4}He. The {sup 4}He-excitation via neutral-current reactions of nu{sub m}u{sub ,t}au and nu-bar{sub m}u{sub ,t}au was found to be one order of magnitude stronger than that via charged-current reactions of nu{sub e} and nu-bar{sub e}. The total energy-weighted cross section
Quenching of the Giant Dipole Resonance Strength at High Excitation Energy
NASA Astrophysics Data System (ADS)
Santonocito, D.; Blumenfeld, Y.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Delaunay, F.; Del Zoppo, A.; Finocchiaro, P.; Frascaria, N.; Hongmei, F.; Lima, V.; Maiolino, C.; Migneco, E.; Piattelli, P.; Sapienza, P.; Scarpaci, J. A.
2007-05-01
The evolution with excitation energy of the Giant Dipole Resonance features in nuclei of mass A≈108-136 is reviewed. We first discuss the results of the experiments performed with MEDEA studying the GDR gamma decay from hot nuclei populated at excitation energies above 300 MeV. The focus of the paper is on the excitation energy region between 160 and 290 MeV. This region has been investigated through the study of the reactions 116Sn + 12C at 17 and 23 A MeV, and 116Sn + 24Mg at 17 A MeV. Gamma-rays were detected using MEDEA in coincidence with evaporation residues detected in MACISTE. The analysis of the gamma-ray spectra and their comparison with statistical calculations are presented. The comparison with γ-ray spectra from the reaction 36Ar + 98Mo at higher excitation energies shows a coherent scenario where a progressive reduction of γ multiplicity relative to predictions for 100% of the Energy Weighted Sum Rule is observed above 200 MeV excitation energy. Finally, the existence of a link between disappearance of collective motion and the liquid-gas phase transitions is discussed.
NASA Astrophysics Data System (ADS)
Latulippe, Maxime; Felfoul, Ouajdi; Dupont, Pierre E.; Martel, Sylvain
2016-02-01
The magnetic navigation of drugs in the vascular network promises to increase the efficacy and reduce the secondary toxicity of cancer treatments by targeting tumors directly. Recently, dipole field navigation (DFN) was proposed as the first method achieving both high field and high navigation gradient strengths for whole-body interventions in deep tissues. This is achieved by introducing large ferromagnetic cores around the patient inside a magnetic resonance imaging (MRI) scanner. However, doing so distorts the static field inside the scanner, which prevents imaging during the intervention. This limitation constrains DFN to open-loop navigation, thus exposing the risk of a harmful toxicity in case of a navigation failure. Here, we are interested in periodically assessing drug targeting efficiency using MRI even in the presence of a core. We demonstrate, using a clinical scanner, that it is in fact possible to acquire, in specific regions around a core, images of sufficient quality to perform this task. We show that the core can be moved inside the scanner to a position minimizing the distortion effect in the region of interest for imaging. Moving the core can be done automatically using the gradient coils of the scanner, which then also enables the core to be repositioned to perform navigation to additional targets. The feasibility and potential of the approach are validated in an in vitro experiment demonstrating navigation and assessment at two targets.
Resonance fluorescence beyond the dipole approximation of a quantum dot in a plasmonic nanostructure
NASA Astrophysics Data System (ADS)
Yang, Chun-Jie; An, Jun-Hong
2016-05-01
The mesoscopic characteristics of a quantum dot (QD), which make the dipole approximation (DA) break down, provide a new dimension to manipulate light-matter interaction [M. L. Andersen et al., Nat. Phys. 7, 215 (2011)], 10.1038/nphys1870. Here we investigate the power spectrum and the second-order correlation property of the fluorescence from a resonantly driven QD placed on a planar metal. It is revealed that due to the pronounced QD spatial extension and the dramatic variation of the triggered surface plasmon near the metal, the fluorescence has a notable contribution from the quadrupole moment. The π -rotation symmetry of the fluorescence to the QD orientation under the DA is broken. By manipulating the QD orientation and quadrupole moment, the spectrum can be switched between the Mollow triplet and a single peak, and the fluorescence characterized by the antibunching in the second-order correlation function can be changed from the weak to the strong radiation regime. Our result is instructive for utilizing the unique mesoscopic effects to develop nanophotonic devices.
NASA Astrophysics Data System (ADS)
Rhine Kumar, A. K.; Arumugam, P.; Dang, N. Dinh
2015-04-01
Apart from the higher limits of isospin and temperature, the properties of atomic nuclei are intriguing and less explored at the limits of lowest but finite temperatures. At very low temperatures there is a strong interplay between the shell (quantal fluctuations), statistical (thermal fluctuations), and residual pairing effects as evidenced from the studies on giant dipole resonance (GDR). In our recent work [Phys. Rev. C 90, 044308 (2014), 10.1103/PhysRevC.90.044308], we have outlined some of our results from a theoretical approach for such warm nuclei where all these effects are incorporated along within the thermal shape fluctuation model (TSFM) extended to include the fluctuations in the pairing field. In this article, we present the complete formalism based on the microscopic-macroscopic approach for determining the deformation energies and a macroscopic approach which links the deformation to GDR observables. We discuss our results for the nuclei 97Tc,120Sn,179Au, and 208Pb, and corroborate with the experimental data available. The TSFM could explain the data successfully at low temperature only with a proper treatment of pairing and its fluctuations. More measurements with better precision could yield rich information about several phase transitions that can happen in warm nuclei.
Signature of clustering in quantum many-body systems probed by the giant dipole resonance
NASA Astrophysics Data System (ADS)
Pandit, Deepak; Mondal, Debasish; Dey, Balaram; Bhattacharya, Srijit; Mukhopadhyay, S.; Pal, Surajit; De, A.; Banerjee, S. R.
2017-03-01
The present experimental study illustrates how large deformations attained by nuclei due to cluster formation are perceived through the giant dipole resonance (GDR) strength function. The high energy GDR γ rays have been measured from 32S at different angular momenta (J ) but similar temperatures in the reactions 4He(Elab=45 MeV )+28Si and 20Ne(Elab=145 MeV )+12C . The experimental data at lower J (˜10 ℏ ) suggests a normal deformation, similar to the ground state value, showing no potential signature of clustering. However, it is found that the GDR lineshape is fragmented into two prominent peaks at high J (˜20 ℏ ) providing a direct measurement of the large deformation developed in the nucleus. The observed lineshape is also completely different from the ones seen for Jacobi shape transition at high J pointing towards the formation of cluster structure in superdeformed states of 32S at such high spin. Thus, the GDR can be regarded as a unique tool to study cluster formation at high excitation energies and angular momenta.
NASA Astrophysics Data System (ADS)
Golubkova, O. S.; Kataeva, T. S.; Shchepkin, D. N.; Asfin, R. E.
2017-06-01
Infrared reflection-absorption spectra of thin films of α-crystalline hexafluoroethane deposited on a gold-plated copper mirror are measured at temperatures of 70 and 80 K. The bands corresponding to strong in the dipole absorption vibrations ν5 and ν10 have complex contours, the shape of which is explained in terms of the resonant dipole-dipole interaction between identical spectrally active molecules of the crystal. Splittings of the complex ν5 and ν10 bands are explained taking into account two effects: the Davydov splitting and the LO-TO splitting of the strong modes. Bands of the asymmetric 13C12CF6 isotopologue in the absorption spectrum of the crystal exhibit an anomalously large isotope shift as compared with the shift in the spectrum of free molecules. This anomaly is explained by intermolecular resonant dipole-dipole interaction of asymmetric 13C12CF6 isotopologue with molecules of the environment, consisting of the most abundant 12C2F6 isotopologue. The correctness of the given interpretation is confirmed calculating these three effects in the model of resonant dipole-dipole interaction.
NASA Astrophysics Data System (ADS)
Brazhnikov, D. V.; Novokreshchenov, A. S.
2017-04-01
The effect of a double structure of saturated absorption resonance in the field of counterpropagating light waves interacting with an atomic gas is studied. The experimental observation of this effect was first reported in 2011 in a work by our colleagues at the P.N. Lebedev Physical Institute of the Russian Academy of Sciences (Laboratory of Frequency Standards). The essence of the effect lies in the fact that, on exciting an open dipole transition, another, narrower, resonance of an opposite sign can be observed at the center of the ordinary saturated absorption resonance. A theoretical analysis of this effect has also been performed in this work in terms of a simple spectroscopic model of an atom with two nondegenerate energy levels without taking into account higher spatial harmonics of atomic polarization and polarizations of light waves (scalar model). The present work is devoted to the development of a theory of the formation of a central narrow resonance for the example of a real F g = 1 → F e = 1 atomic transition and to the study of its main characteristics (amplitude, width, contrast, and amplitude-to-width ratio). In addition, the theoretical results obtained without taking into account the influence of higher spatial harmonics and with inclusion of the influence of first higher harmonics are compared. This comparison shows that their influence on the parameters of the new nonlinear resonance is strong even in moderately intense light fields ( R γ, where R is the Rabi frequency). The results of this study can be of interest for quantum metrology, as well as for many experiments in which the laser-radiation frequency is stabilized by the saturated absorption resonance on open dipole transitions in atoms and molecules.
Intense {gamma}-Ray Source in the Giant-Dipole-Resonance Range Driven by 10-TW Laser Pulses
Giulietti, A.; Gamucci, A.; Gizzi, L. A.; Labate, L.; Bourgeois, N.; Marques, J. R.; Ceccotti, T.; Dobosz, S.; D'Oliveira, P.; Monot, P.; Popescu, H.; Reau, F.; Martin, P.; Galy, J.; Hamilton, D. J.; Giulietti, D.
2008-09-05
A {gamma}-ray source with an intense component around the giant dipole resonance for photonuclear absorption has been obtained via bremsstrahlung of electron bunches driven by a 10-TW tabletop laser. 3D particle-in-cell simulation proves the achievement of a nonlinear regime leading to efficient acceleration of several sequential electron bunches per each laser pulse. The rate of the {gamma}-ray yield in the giant dipole resonance region (8
RESONANT EXTRACTION PARAMETERS FOR THE AGS BOOSTER.
BROWN,K.A.; CULLEN,J.; GLENN,J.W.; MAPES,M.; MARNERIS,I.; TSOUPAS,N.; SNYDSTRUP,L.; VAN ASSELT,W.
2001-06-18
Brookhaven's AGS Booster is the injector for the AGS. It is being modified to send resonant extracted heavy ions to a new beam line, the Booster Applications Facility (BAF). The design of the resonant extraction system for BAF was described in [1]. This note will give a more detailed description of the system and describe the predicted resonant beam time structure. We will describe tune space manipulations necessary to extract the resonant beam at the maximum Booster rigidity, schemes for performing resonant extraction, and describe the modifications required to perform bunched beam extraction to the BAF facility.
Ryezayeva, N; Hartmann, T; Kalmykov, Y; Lenske, H; von Neumann-Cosel, P; Ponomarev, V Yu; Richter, A; Shevchenko, A; Volz, S; Wambach, J
2002-12-30
A high-resolution (gamma,gamma') study of the electric dipole response in 208Pb at the S-DALINAC reveals a resonance structure centered around the neutron emission threshold. Microscopic quasiparticle phonon model calculations in realistic model spaces including the coupling to complex configurations are able to describe the data in great detail. The resonance is shown to result from surface density oscillations of the neutron skin relative to an approximately isospin-saturated core. It also forms an integral part of a toroidal E1 mode representing an example of vortex collective motion in nuclei.
Shimada, Rintaro; Hamaguchi, Hiro-o
2014-05-28
We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-β-carotene (β-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute β-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of β-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of β-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of β-carotene with the vibrations of a proximate solvent molecule through solute–solvent dipole–dipole and dipole–quadrupole interactions. It is shown that the infrared active modes arise from the dipole–dipole interaction, whereas Raman active modes from the dipole–quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å.
NASA Astrophysics Data System (ADS)
Zobov, V. E.; Kucherov, M. M.
2017-01-01
The singularities of the time autocorrelation functions (ACFs) of magnetically diluted spin systems with dipole-dipole interaction (DDI), which determine the high-frequency asymptotics of autocorrelation functions and the wings of a magnetic resonance line, are studied. Using the self-consistent fluctuating local field approximation, nonlinear equations are derived for autocorrelation functions averaged over the independent random arrangement of spins (magnetic atoms) in a diamagnetic lattice with different spin concentrations. The equations take into account the specificity of the dipole-dipole interaction. First, due to its axial symmetry in a strong static magnetic field, the autocorrelation functions of longitudinal and transverse spin components are described by different equations. Second, the long-range type of the dipole-dipole interaction is taken into account by separating contributions into the local field from distant and near spins. The recurrent equations are obtained for the expansion coefficients of autocorrelation functions in power series in time. From them, the numerical value of the coordinate of the nearest singularity of the autocorrelation function is found on the imaginary time axis, which is equal to the radius of convergence of these expansions. It is shown that in the strong dilution case, the logarithmic concentration dependence of the coordinate of the singularity is observed, which is caused by the presence of a cluster of near spins whose fraction is small but contribution to the modulation frequency is large. As an example a silicon crystal with different 29Si concentrations in magnetic fields directed along three crystallographic axes is considered.
Search for magnetic dipole strength and giant spin-flip resonances in heavy nuclei. [120 to 200 MeV
Horen, D J
1980-01-01
A description is given of the use of high-resolution (n,n) scattering and the (p,n) reaction as tools to investigate highly excited states, with emphasis on information pertaining to magnetic dipole strength and giant spin-flip resonances in heavy nuclei. It is shown how the ability to determine uniquely the spins and parities of resonances observed in neutron scattering has been instrumental to an understanding of the distribution of M1 strength in /sup 207/ /sup 208/Pb. Some recent results of (p,n) studies with intermediate energy protons are discussed. Energy systematics of the giant Gamow-Teller (GT) resonance as well as new ..delta..l = ..delta..S = 1 resonance with J/sup ..pi../ = (1,2)/sup -/ are presented. It is shown how the (p,n) reaction might be useful in locating M1 strength in heavy nuclei. 20 figures.
Isoscalar monopole and dipole excitations of cluster states and giant resonances in 12C
NASA Astrophysics Data System (ADS)
Kanada-En'yo, Yoshiko
2016-05-01
The isoscalar monopole (ISM) and dipole (ISD) excitations in 12C are investigated theoretically with the shifted antisymmetrized molecular dynamics (AMD) plus 3 α -cluster generator coordinate method (GCM). The small-amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by a small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large-amplitude cluster modes are incorporated by superposing 3 α -cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present a calculation that describes the ISM and ISD excitations over a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, although the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the distance motion between α clusters, and they split into a couple of states because of the angular motion of α clusters. The low-energy ISM strengths exhaust 26% of the energy-weighted sum rule, which is consistent with the experimental data for the 12C(02+; 7.65 MeV) and 12C(03+; 10.3 MeV) measured by (e ,e') ,(α ,α') , and (6Li,6Li' ) scatterings. In the calculated low-energy ISD strengths, two 1- states (the 11- and 12- states) with the significant strengths are obtained over E =10 -15 MeV. The results indicate that the ISD excitations can be a good probe to experimentally search for new cluster states such as the 12C(12-) obtained in the present calculation.
Onset of quenching of the giant dipole resonance at high excitation energies
NASA Astrophysics Data System (ADS)
Santonocito, D.; Blumenfeld, Y.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Delaunay, F.; Del Zoppo, A.; Finocchiaro, P.; Hongmei, F.; Lima, V.; Maiolino, C.; Migneco, E.; Piattelli, P.; Sapienza, P.; Scarpaci, J. A.; Wieland, O.
2014-11-01
The evolution of the giant dipole resonance (GDR) properties in nuclei of mass A =120 to 132 has been investigated in an excitation energy range between 150 and 270 MeV through the study of complete and nearly complete fusion reactions using 116Sn beams at 17 A and 23 A MeV from the cyclotron of the Laboratorio Nazionale del Sud impinging on 12C and 24Mg targets. γ rays and light charged particles were detected using the multi-element detector array MEDEA in coincidence with evaporation residues detected by using mass and charge identification spectrometry with telescope (MACISTE). Light-charged-particle energy spectra were analyzed within the framework of a multiple-source-emission scenario by using a fitting procedure to determine the amount of pre-equilibrium emission and deduce the excitation energies reached in the compound nuclei. A detailed analysis of the γ -ray spectra and their comparison with statistical model calculations is presented. Evidence of a quenching of the GDR gamma yield was found at 270 MeV excitation energy. The quenching effect becomes progressively more important with increasing excitation energy, as observed when the comparison is extended to data from the reaction 36Ar+96Mo at 37 A MeV where hot nuclei were populated up to 430 MeV excitation energy. A coherent scenario emerges indicating the existence of a limiting excitation energy for the collective motion of about E*/A =2.1 MeV for systems of mass A =105 to 111 while a slightly lower value was observed for nuclei of mass A ˜132 . The existence of a possible link between GDR disappearance and the liquid-gas phase transition is discussed.
Nature of low-lying electric dipole resonance excitations in 74Ge
NASA Astrophysics Data System (ADS)
Negi, D.; Wiedeking, M.; Lanza, E. G.; Litvinova, E.; Vitturi, A.; Bark, R. A.; Bernstein, L. A.; Bleuel, D. L.; Bvumbi, S.; Bucher, T. D.; Daub, B. H.; Dinoko, T. S.; Easton, J. L.; Görgen, A.; Guttormsen, M.; Jones, P.; Kheswa, B. V.; Khumalo, N. A.; Larsen, A. C.; Lawrie, E. A.; Lawrie, J. J.; Majola, S. N. T.; Masiteng, L. P.; Nchodu, M. R.; Ndayishimye, J.; Newman, R. T.; Noncolela, S. P.; Orce, J. N.; Papka, P.; Pellegri, L.; Renstrøm, T.; Roux, D. G.; Schwengner, R.; Shirinda, O.; Siem, S.
2016-08-01
Isospin properties of dipole excitations in 74Ge are investigated using the (α ,α'γ ) reaction and compared to (γ ,γ' ) data. The results indicate that the dipole excitations in the energy region of 6 to 9 MeV adhere to the scenario of the recently found splitting of the region of dipole excitations into two separated parts: one at low energy, being populated by both isoscalar and isovector probes, and the other at high energy, excited only by the electromagnetic probe. Relativistic quasiparticle time blocking approximation (RQTBA) calculations show a reduction in the isoscalar E 1 strength with an increase in excitation energy, which is consistent with the measurement.
The reaction gammap-->pi0gamma'p and the magnetic dipole moment of the Delta+ 1232 resonance.
Kotulla, M; Ahrens, J; Annand, J R M; Beck, R; Caselotti, G; Fog, L S; Hornidge, D; Janssen, S; Krusche, B; McGeorge, J C; McGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Pfeiffer, M; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Watts, D P
2002-12-30
The reaction gammap-->pi(0)gamma'p has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between sqrt[s]=1221-1331 MeV. The cross section's differential in angle and energy have been determined for the photon gamma' in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the Delta(+)(1232) resonance and, for the first time, a value of mu(Delta(+))=[2.7(+1.0)(-1.3)(stat)+/-1.5(syst)+/-3(theor)]mu(N) has been extracted.
Conformation-Selective Resonant Photoelectron Spectroscopy via Dipole-Bound States of Cold Anions.
Huang, Dao-Ling; Liu, Hong-Tao; Ning, Chuan-Gang; Wang, Lai-Sheng
2015-06-18
Molecular conformation is important in chemistry and biochemistry. Conformers connected by low energy barriers can only be observed at low temperatures and are difficult to be separated. Here we report a new method to obtain conformation-selective spectroscopic information about dipolar molecular radicals via dipole-bound excited states of the corresponding anions cooled in a cryogenic ion trap. We observed two conformers of cold 3-hydroxyphenoxide anions [m-HO(C6H4)O(-)] in high-resolution photoelectron spectroscopy and measured different electron affinities, 18,850(8) and 18,917(5) cm(-1), for the syn and anti 3-hydroxyphenoxy radicals, respectively. We also observed dipole-bound excited states for m-HO(C6H4)O(-) with different binding energies for the two conformers due to the different dipole moments of the corresponding 3-hydroxyphenoxy radicals. Excitations to selected vibrational levels of the dipole-bound states result in conformation-selective photoelectron spectra. This method should be applicable to conformation-selective spectroscopic studies of any anions with dipolar neutral cores.
NASA Astrophysics Data System (ADS)
Tichit, Paul-Henri; Burokur, Shah Nawaz; Qiu, Cheng-Wei; de Lustrac, André
2013-09-01
It has long been conjectured that isotropic radiation by a simple coherent source is impossible due to changes in polarization. Though hypothetical, the isotropic source is usually taken as the reference for determining a radiator’s gain and directivity. Here, we demonstrate both theoretically and experimentally that an isotropic radiator can be made of a simple and finite source surrounded by electric-field-driven LC resonator metamaterials designed by space manipulation. As a proof-of-concept demonstration, we show the first isotropic source with omnidirectional radiation from a dipole source (applicable to all distributed sources), which can open up several possibilities in axion electrodynamics, optical illusion, novel transformation-optic devices, wireless communication, and antenna engineering. Owing to the electric- field-driven LC resonator realization scheme, this principle can be readily applied to higher frequency regimes where magnetism is usually not present.
Tichit, Paul-Henri; Burokur, Shah Nawaz; Qiu, Cheng-Wei; de Lustrac, André
2013-09-27
It has long been conjectured that isotropic radiation by a simple coherent source is impossible due to changes in polarization. Though hypothetical, the isotropic source is usually taken as the reference for determining a radiator's gain and directivity. Here, we demonstrate both theoretically and experimentally that an isotropic radiator can be made of a simple and finite source surrounded by electric-field-driven LC resonator metamaterials designed by space manipulation. As a proof-of-concept demonstration, we show the first isotropic source with omnidirectional radiation from a dipole source (applicable to all distributed sources), which can open up several possibilities in axion electrodynamics, optical illusion, novel transformation-optic devices, wireless communication, and antenna engineering. Owing to the electric- field-driven LC resonator realization scheme, this principle can be readily applied to higher frequency regimes where magnetism is usually not present.
Splitting of the pygmy dipole resonance in Ba138 and Ce140 observed in the (α,α'γ) reaction
NASA Astrophysics Data System (ADS)
Endres, J.; Savran, D.; Berg, A. M. Van Den; Dendooven, P.; Fritzsche, M.; Harakeh, M. N.; Hasper, J.; Wörtche, H. J.; Zilges, A.
2009-09-01
The N=82 nuclei Ce140 and Ba138 have been investigated by means of the (α,α'γ) coincidence method to study the pygmy dipole resonance (PDR). The experiments have been performed at the AGOR cyclotron at KVI, Groningen, at a primary beam energy of Eα=136 MeV. The Big-Bite Spectrometer and seven large-volume high-purity germanium detectors were used in coincidence to perform a simultaneous spectroscopy of the scattered α particles and the γ decay. The comparison with results of nuclear resonance fluorescence experiments reveals a splitting of the PDR into two components. Up to about 6 MeV the same states that could be observed in (γ,γ') are also excited in α-scattering experiments, whereas the higher-lying states are missing in the (α,α'γ) reaction. This indicates a structural splitting of the PDR into two modes with different underlying structure.
NASA Astrophysics Data System (ADS)
Haiwei, Mu; Jingwei, Lv; Zhaoting, Liu; Shijie, Zheng; Lin, Yang; Tao, Sun; Qiang, Liu; Chao, Liu
2016-04-01
Optical properties of localized surface plasmon resonances (LSPR) of Ag/ITO sliced nanosphere have been studied using discrete dipole approximation and plasmon hybridization theory. It is found that different morphologies of sliced nanosphere can induce distinctive features in the extinction spectra. In the meanwhile, gap distances and refractive index of the surrounding medium could modulate the plasmon hybridization and the LSPR shifting. At large separation, the shift of LSPR peaks for the nanosphere sliced in halves consisting of ITO and Ag is small and insensitive to the gap distance in the weak coupling, whereas smaller separation exhibits a distinct red shift. Additionally, multiple resonance peaks are excited for the nanosphere sliced in quarters consisting of ITO and Ag. In this situation, electric field is mainly distributed in the gap region of sliced nanosphere and the central point. These results indicate that different morphologies of sliced nanosphere could create abundant tunable LSPR modes, which provides potential for multiplex optical sensing.
Probing nuclear shapes close to the fission limit with the giant dipole resonance in {sup 216}Rn
Kmiecik, M.; Maj, A.; Brekiesz, M.; Krolas, W.; Meczynski, W.; Styczen, J.; Zieblinski, M.; Million, B.; Bracco, A.; Camera, F.; Benzoni, G.; Leoni, S.; Wieland, O.; Brambilla, S.; Herskind, B.; Kicinska-Habior, M.; Dubray, N.; Dudek, J.; Schunck, N.
2004-12-01
The gamma-ray decay of the giant dipole resonance (GDR) in the compound nucleus {sup 216}Rn formed with the reaction {sup 18}O+{sup 198}Pt at the bombarding energy of 96 MeV was investigated. High-energy gamma-ray spectra in coincidence with both prompt and delayed low-energy transitions were measured. The obtained GDR width at the average temperature
NASA Astrophysics Data System (ADS)
Arsenyev, N. N.; Severyukhin, A. P.; Voronov, V. V.; Van Giai, Nguyen
2017-05-01
Starting from the quasiparticle random phase approximation based on the Skyrme interaction SLy5, we study the effects of phonon-phonon coupling (PPC) on the low-energy electric dipole response in Ca-5840. Using the same set of parameters we describe available experimental data for 40,44,48Ca and give the prediction for Ca-5850. The inclusion of the PPC results in the formation of low-energy 1- states. There is an impact of the PPC effect on low-energy E 1 strength of 40,44,48Ca. The PPC effect on the electric dipole polarizability is discussed. We predict a strong increase of the summed E 1 strength below 10 MeV, with increasing neutron number from 48Ca until 58Ca.
Single-level resonance parameters fit nuclear cross-sections
NASA Technical Reports Server (NTRS)
Drawbaugh, D. W.; Gibson, G.; Miller, M.; Page, S. L.
1970-01-01
Least squares analyses of experimental differential cross-section data for the U-235 nucleus have yielded single level Breit-Wigner resonance parameters that fit, simultaneously, three nuclear cross sections of capture, fission, and total.
Influence of resonance parameters' correlations on the resonance integral uncertainty; 55Mn case
NASA Astrophysics Data System (ADS)
Žerovnik, Gašper; Trkov, Andrej; Capote, Roberto; Rochman, Dimitri
2011-03-01
For nuclides with a large number of resonances the covariance matrix of resonance parameters can become very large and expensive to process in terms of the computation time. By converting covariance matrix of resonance parameters into covariance matrices of background cross-section in a more or less coarse group structure a considerable amount of computer time and memory can be saved. The question is how important is the information that is discarded in the process. First, the uncertainty of the 55Mn resonance integral was estimated in narrow resonance approximation for different levels of self-shielding using Bondarenko method by random sampling of resonance parameters according to their covariance matrices from two different 55Mn evaluations: one from Nuclear Research and Consultancy Group NRG (with large uncertainties but no correlations between resonances), the other from Oak Ridge National Laboratory (with smaller uncertainties but full covariance matrix). We have found out that if all (or at least significant part of the) resonance parameters are correlated, the resonance integral uncertainty greatly depends on the level of self-shielding. Second, it was shown that the commonly used 640-group SAND-II representation cannot describe the increase of the resonance integral uncertainty. A much finer energy mesh for the background covariance matrix would have to be used to take the resonance structure into account explicitly, but then the objective of a more compact data representation is lost.
Peric, Mirna; Bales, Barney L; Peric, Miroslav
2012-03-22
The work in part 6 of this series (J. Phys. Chem. A 2009, 113, 4930), addressing the task of separating the effects of Heisenberg spin exchange (HSE) and dipole-dipole interactions (DD) on electron paramagnetic resonance (EPR) spectra of nitroxide spin probes in solution, is extended experimentally and theoretically. Comprehensive measurements of perdeuterated 2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl (pDT) in squalane, a viscous alkane, paying special attention to lower temperatures and lower concentrations, were carried out in an attempt to focus on DD, the lesser understood of the two interactions. Theoretically, the analysis has been extended to include the recent comprehensive treatment by Salikhov (Appl. Magn. Reson. 2010, 38, 237). In dilute solutions, both interactions (1) introduce a dispersion component, (2) broaden the lines, and (3) shift the lines. DD introduces a dispersion component proportional to the concentration and of opposite sign to that of HSE. Equations relating the EPR spectral parameters to the rate constants due to HSE and DD have been derived. By employing nonlinear least-squares fitting of theoretical spectra to a simple analytical function and the proposed equations, the contributions of the two interactions to items 1-3 may be quantified and compared with the same parameters obtained by fitting experimental spectra. This comparison supports the theory in its broad predictions; however, at low temperatures, the DD contribution to the experimental dispersion amplitude does not increase linearly with concentration. We are unable to deduce whether this discrepancy is due to inadequate analysis of the experimental data or an incomplete theory. A new key aspect of the more comprehensive theory is that there is enough information in the experimental spectra to find items 1-3 due to both interactions; however, in principle, appeal must be made to a model of molecular diffusion to separate the two. The permanent diffusion model is used to
Random sampling and validation of covariance matrices of resonance parameters
NASA Astrophysics Data System (ADS)
Plevnik, Lucijan; Zerovnik, Gašper
2017-09-01
Analytically exact methods for random sampling of arbitrary correlated parameters are presented. Emphasis is given on one hand on the possible inconsistencies in the covariance data, concentrating on the positive semi-definiteness and consistent sampling of correlated inherently positive parameters, and on the other hand on optimization of the implementation of the methods itself. The methods have been applied in the program ENDSAM, written in the Fortran language, which from a file from a nuclear data library of a chosen isotope in ENDF-6 format produces an arbitrary number of new files in ENDF-6 format which contain values of random samples of resonance parameters (in accordance with corresponding covariance matrices) in places of original values. The source code for the program ENDSAM is available from the OECD/NEA Data Bank. The program works in the following steps: reads resonance parameters and their covariance data from nuclear data library, checks whether the covariance data is consistent, and produces random samples of resonance parameters. The code has been validated with both realistic and artificial data to show that the produced samples are statistically consistent. Additionally, the code was used to validate covariance data in existing nuclear data libraries. A list of inconsistencies, observed in covariance data of resonance parameters in ENDF-VII.1, JEFF-3.2 and JENDL-4.0 is presented. For now, the work has been limited to resonance parameters, however the methods presented are general and can in principle be extended to sampling and validation of any nuclear data.
Effect of the. delta. (1236) resonance on magnetic dipole properties of nuclei
Lawson, R.D.
1983-01-01
The effect of the ..delta..(1236) resonance on magnetic moments, M1 transition rates and beta decay is discussed. The main effect of including this resonance is to renormalize the g-factor of the valence nucleons and explicit values for this renormalization are given. The effect on l-forbidden M1 transitions is investigated.
Reflection and transmission properties of a metasurface composed of resonant loaded wire dipoles.
Awan, Z A
2016-05-20
A considered metasurface is assumed to consist of a two-dimensional periodic arrangement of inductively loaded wires. The effects of incident angles and inductive loads upon equivalent surface impedance, reflection, and transmission properties of this metasurface have been investigated using numerical simulations. It is shown that at a particular frequency and angle, a metasurface can be cloaked for the incoming incident wave with nearly zero reflection. It is further studied that this approximate zero reflection is independent of the inductances of the inductively loaded wire dipoles.
Neutron-skin thickness of 208Pb from the energy of the anti-analogue giant dipole resonance
NASA Astrophysics Data System (ADS)
Krasznahorkay, A.; Paar, N.; Vretenar, D.; Harakeh, M. N.
2013-05-01
The energy of the charge-exchange anti-analogue giant dipole resonance (AGDR) has been calculated for the 208Pb isotope using the state-of-the-art fully self-consistent relativistic proton-neutron quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. It is shown that the AGDR centroid energy is very sensitively related to the corresponding neutron-skin thickness. The neutron-skin thickness of 208Pb has been determined very precisely by comparing the theoretical results with the available experimental data on E(AGDR). The result ΔRpn = 0.161 ± 0.042 agrees nicely with the previous experimental results.
Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments
Trbovich, M J; Barry, D P; Slovacek, R E; Danon, Y; Block, R C; Francis, N C; Lubert, M; Burke, J A; Drindak, N J; Lienweber, G; Ballad, R
2007-02-06
The focus of this work is to determine the resonance parameters for stable hafnium isotopes in the 0.005 - 200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. Accurate hafnium cross sections and resonance parameters are needed in order to quantify the effects of hafnium found in zirconium, a metal commonly used in reactors. The accuracy of the cross sections and the corresponding resonance parameters used in current nuclear analysis tools are rapidly becoming the limiting factor in reducing the overall uncertainty on reactor physics calculations. Experiments measuring neutron capture and transmission are routinely performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time-of flight technique. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m, respectively. Capture experiments were performed using a sixteen section NaI multiplicity detector at a flight path length of 25 m. These experiments utilized several thicknesses of metallic and isotope-enriched liquid Hf samples. The liquid Hf samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analyses were performed using the R-matrix Bayesian code SAMMY. A combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005 - 200 eV. Additionally, resonance integrals were calculated, along with errors for each hafnium isotope, using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previous values. The {sup 176}Hf resonance integral, based on this work, is approximately 73% higher than the ENDF/B-VI value. This is due primarily to the changes to resonance parameters in the 8 eV resonance, the neutron width presented in this work is more than twice that of the previous value. The calculated elemental
On random sampling of correlated resonance parameters with large uncertainties
NASA Astrophysics Data System (ADS)
Žerovnik, Gašper; Capote, Roberto; Trkov, Andrej
2013-09-01
Three different methods for multivariate random sampling of correlated resonance parameters are proposed: the diagonalization method, the Metropolis method, and the correlated sampling method. For small relative uncertainties (typical for s-wave resonances) and weak correlations all methods are equivalent. Differences arise under difficult conditions: large relative uncertainties of inherently positive parameters (typical for widths of higher-l-wave resonances) and/or strong correlations between a large number of parameters. The methods are tested on realistic examples; advantages and disadvantages of each method are pointed out. The correlated sampling method is the only method which produces consistent samples under any conditions. In the field of reactor physics, these methods are mostly used for the sampling of nuclear data, however, they may be used for any data with given uncertainties and correlations.
Isoscalar giant dipole resonance in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb
Clark, H. L.; Lui, Y.-W.; Youngblood, D. H.
2001-03-01
Strength functions for isoscalar dipole excitations in {sup 90}Zr, {sup 116}Sn, and {sup 208}Pb have been measured with inelastic scattering of 240 MeV {alpha} particles at small angles. The isoscalar E1 strength distribution in each nucleus is found to consist of a broad component at E{sub x}{approx}114/A{sup 1/3}MeV containing approximately 100% of the E1 EWSR and a narrower one at E{sub x}{approx}72/A{sup 1/3}MeV containing 15--28% of the total isoscalar E1 strength. The higher component is the compression mode E1 strength previously reported only in {sup 208}Pb, whereas the lower component may be a new mode not reported previously, but suggested by recent RPA-HF and relativistic mean field calculations.
Evaluation of the Covariance Matrix of Estimated Resonance Parameters
NASA Astrophysics Data System (ADS)
Becker, B.; Capote, R.; Kopecky, S.; Massimi, C.; Schillebeeckx, P.; Sirakov, I.; Volev, K.
2014-04-01
In the resonance region nuclear resonance parameters are mostly obtained by a least square adjustment of a model to experimental data. Derived parameters can be mutually correlated through the adjustment procedure as well as through common experimental or model uncertainties. In this contribution we investigate four different methods to propagate the additional covariance caused by experimental or model uncertainties into the evaluation of the covariance matrix of the estimated parameters: (1) including the additional covariance into the experimental covariance matrix based on calculated or theoretical estimates of the data; (2) including the uncertainty affected parameter in the adjustment procedure; (3) evaluation of the full covariance matrix by Monte Carlo sampling of the common parameter; and (4) retroactively including the additional covariance by using the marginalization procedure of Habert et al.
Neutron Resonance Parameters and Covariance Matrix of 239Pu
Derrien, Herve; Leal, Luiz C; Larson, Nancy M
2008-08-01
In order to obtain the resonance parameters in a single energy range and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the code SAMMY. The most recent experimental data were analyzed or reanalyzed in the energy range thermal to 2.5 keV. The normalization of the fission cross section data was reconsidered by taking into account the most recent measurements of Weston et al. and Wagemans et al. A full resonance parameter covariance matrix was generated. The method used to obtain realistic uncertainties on the average cross section calculated by SAMMY or other processing codes was examined.
A resonant scanning dipole-antenna probe for enhanced nanoscale imaging.
Neumann, Lars; van 't Oever, Jorick; van Hulst, Niek F
2013-11-13
We present a scanning antenna probe that provides 35 nm optical hotspots with a 16-fold excitation enhancement. A resonant optical antenna, tuned to operation in the visible, is carved into the aluminum-coated scanning probe. The antenna resonances, field localization, excitation, and polarization response are probed in the near-field by scanning over single fluorescent nanobeads. At the same time, the distance-dependent coupling of the emission to the antenna mode is mapped. Good agreement with theory is obtained. The presented scanning antenna approach is useful for both nanoscale plasmonic mode imaging and (bio)imaging.
Double helix dipole design applied to magnetic resonance: a novel NMR coil.
Alonso, J; Soleilhavoup, A; Wong, A; Guiga, A; Sakellariou, D
2013-10-01
A new radio frequency coil design for NMR experiments is presented. The coil generates a magnetic field purely perpendicular to the longitudinal axis of the main magnet, and its sensitivity is higher than the traditional transversal resonators. This is achieved by adding the contribution of two tilted solenoid coils fed with opposite currents. The work presents the mathematical model for the new coil, numerical simulations performed to validate that model and a comparison with an equivalent saddle coil. The new design is tested experimentally in low- and high-field NMR experiments and compared with results obtained with equivalent saddle coils. The results lead to conclude that the new design provides better sensitivity than the transverse resonators commonly used in NMR. Copyright © 2013 Elsevier Inc. All rights reserved.
Parameter measurement of synchronous reluctance motor using LC resonance
NASA Astrophysics Data System (ADS)
Ahn, Joonseon; Kim, Ki-Chan; Lee, Ju
2006-04-01
The motor characterizing parameters are most important factors to drive precisely, effectively, and robustly. Especially, the exact knowledge of synchronous inductance is necessary to control the torque precisely in synchronous reluctance motor (SynRM). Therefore many works have been done for the exact measurement of motor parameters. In this paper, we propose the simple method of measuring the motor parameters, especially measuring the synchronous inductance of SynRM, which can overcome the demerits of conventional methods and measure the exact values. The proposed method uses the resonance phenomenon between the phase inductance and capacitors externally connected.
NASA Technical Reports Server (NTRS)
Omidvar, K.
1971-01-01
Expressions for the excitation cross section of the highly excited states of the hydrogenlike atoms by fast charged particles have been derived in the dipole approximation of the semiclassical impact parameter and the Born approximations, making use of a formula for the asymptotic expansion of the oscillator strength of the hydrogenlike atoms given by Menzel. When only the leading term in the asymptotic expansion is retained, the expression for the cross section becomes identical to the expression obtained by the method of the classical collision and correspondence principle given by Percival and Richards. Comparisons are made between the Bethe coefficients obtained here and the Bethe coefficients of the Born approximation for transitions where the Born calculation is available. Satisfactory agreement is obtained only for n yields n + 1 transitions, with n the principal quantum number of the excited state.
New Resonance Parameter Evaluation of Cl Neutron Cross Sections
Sayer, R.O.; Guber, K.H.; Leal, L.C.; Larson, N.M.
2005-05-24
Better measurements and evaluations are needed for many elements where the existing evaluations or the underlying nuclear cross-section data are not sufficiently accurate for reliable calculation of criticality safety margins. Deficiencies in the existing ENDF/B-VI data evaluation for Cl led to our resonance parameter evaluation of Cl neutron cross sections in the resolved resonance region with the multilevel Reich-Moore R-matrix formalism. Our evaluation takes advantage of recent high-resolution capture and transmission measurements at the Oak Ridge Electron Linear Accelerator (ORELA) as well as older total cross-section measurements at Karlsruhe (KFK) to extend the resolved resonance energy range to 1.2 MeV with much more accurate representation of the data than previous evaluations.
Parameters optimization for magnetic resonance coupling wireless power transmission.
Li, Changsheng; Zhang, He; Jiang, Xiaohua
2014-01-01
Taking maximum power transmission and power stable transmission as research objectives, optimal design for the wireless power transmission system based on magnetic resonance coupling is carried out in this paper. Firstly, based on the mutual coupling model, mathematical expressions of optimal coupling coefficients for the maximum power transmission target are deduced. Whereafter, methods of enhancing power transmission stability based on parameters optimal design are investigated. It is found that the sensitivity of the load power to the transmission parameters can be reduced and the power transmission stability can be enhanced by improving the system resonance frequency or coupling coefficient between the driving/pick-up coil and the transmission/receiving coil. Experiment results are well conformed to the theoretical analysis conclusions.
Chen, Ziyu; Dai, Hongwei; Liu, Jiaming; Xu, Hui; Li, Zixuan; Zhou, Zhang-Kai; Han, Jun-Bo
2013-07-29
Au triangular nanoprisms with strong dipole plasmon absorption peak at 1240 nm were prepared by wet chemical methods. Both numerical calculations and experiments were carried out to investigate the optical properties of the samples. Finite difference time domain (FDTD) and Local Density of States (LDOS) calculations demonstrate that strong electric field enhancement and large LDOS can be obtained at tip areas of the Au triangular nanoprisms. Z scan techniques were used to characterize the nonlinear absorption, nonlinear refraction, as well as one- and two-photon figures of merit (W and T, respectively) of the sample. The results show that maximum nonlinear refractive index can be obtained around the resonance absorption wavelength of 1240 nm, detuning the wavelength from the absorption peak will lead to the decrease of the nonlinear refractive index n(2), while the nonlinear absorption coefficient β doesn't change much with the wavelength. This large wavelength dependence of n(2) and small change of β enable the sample to satisfy the all-optical switching demand of W> 1 and T< 1 easily in a large wavelength range of 1200-1300 nm. These significant nonlinear properties of the sample imply that Au triangular nanoprism is a good candidate for future optical switches in infrared optical communication wavelength region.
NASA Astrophysics Data System (ADS)
Thiep, Tran Duc; An, Truong Thi; Cuong, Phan Viet; Vinh, Nguyen The; Hue, Bui Minh; Belov, A. G.; Maslov, O. D.; Mishinsky, G. V.; Zhemenik, V. I.
2017-01-01
We have determined the isomeric ratios of isomeric pairs 97m,gNb, 95m,gNb and 91m,gMo produced in 98Mo(γ, p)97m,gNb, 96Mo(γ, p)95m,gNb and 92Mo(γ, n)91m,gMo photonuclear reactions in the giant dipole resonance (GDR) region by the activation method. The results were analyzed, discussed and compared with the similar data from literature to examine the role of excitation energy, neutron configuration, channel effect and direct and pre-equilibrium processes in (γ, p) photonuclear reactions. In this work the isomeric ratios for 97m,gNb from 14 to 19 MeV, for 195m,gNb from14 to 24 MeV except 20 and 23.5 MeV and for 91m,gMo at 14 and 15 MeV are the first time measurements.
NASA Astrophysics Data System (ADS)
Watson, J. W.
1996-10-01
For charge-exchange reactions at medium energies, one of the dominant features of small-angle spectra is the excitation of the ΔT = 1, ΔL = 1, ΔS = 1 isovector "spin-dipole" resonance (SDR). We describe how polarization-transfer measurements can be used to identify the overlapping J^π = 0^-, 1^-, and 2^- components of the SDR. Results for ^16O(p,n) and ^40Ca(p,n) using data (J. W. Watson et al.), Nucl. Phys. A577, 79c (1994). (J. W. Watson et al.), Nucl. Phys. A599, 211c (1996). for the transverse polarization-transfer coefficient D_NN' are presented and compared with distorted-wave impulse approximation (DWIA) calculations with theory of finite Fermi systems (TFFS) wavefunctions. (F. A. Gareev et al.), Sov. J. Part. Nucl. 19, 373 (1988). Future experiments will utilize complete sets of polarization-transfer data to extract the longitudinal and transverse spin responses,(M. Ichimura and K. Kawahigashi, Phys. Rev. C45), 1822 (1992). which will provide a more definitive separation of the different J^πs in the SDR. footnote Supported by NSF PHY 94-09265
Bound free electron-positron pair production accompanied by giant dipole resonances
Senguel, M. Y.; Gueclue, M. C.
2011-01-15
At the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), for example, virtual photons produce many particles. At small impact parameters where the colliding nuclei make peripheral collisions, photon fluxes are very large and these are responsible for the multiple photonuclear interactions. Free pair productions, bound free pair productions, and nuclear Coulomb excitations are important examples of such interactions, and these processes play important roles in the beam luminosity at RHIC and LHC. Here we obtained the impact parameter dependence of bound free pair production cross sections and by using this probability we obtained bound free electron-positron pair production with nuclear breakup for heavy ion collisions at RHIC and LHC. We also compared our results to the other calculations.
Some principles in choosing parameters of magnetic resonance tomographs
NASA Astrophysics Data System (ADS)
Volobuev, A. N.
2017-01-01
The problem of amplifying the signal that ensures the visualization of internal organs in the magnetic resonance tomograph due to the optimal selection of some of its parameters has been considered. The operating principle of the tomograph has been analyzed. The relation between the angle of the magnetic moment precession in hydrogen nuclei in an organism, the frequency of the ac magnetic field exciting this precession, and the constant magnetic field used has been determined using quantum-mechanical concepts. This relation makes it possible to determine the optimal parameters for tomograph operation.
NASA Astrophysics Data System (ADS)
Iwamoto, C.; Utsunomiya, H.; Tamii, A.; Akimune, H.; Nakada, H.; Shima, T.; Yamagata, T.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Shimbara, Y.; Nagashima, M.; Suzuki, T.; Fujita, H.; Sakuda, M.; Mori, T.; Izumi, T.; Okamoto, A.; Kondo, T.; Bilgier, B.; Kozer, H. C.; Lui, Y.-W.; Hatanaka, K.
2012-06-01
A high-resolution measurement of inelastic proton scattering off Zr90 near 0° was performed at 295 MeV with a focus on a pronounced strength previously reported in the low-energy tail of giant dipole resonance. A forest of fine structure was observed in the excitation energy region 7-12 MeV. A multipole decomposition analysis of the angular distribution for the forest was carried out using the ECIS95 distorted-wave Born approximation code with the Hartree-Fock plus random-phase approximation model of E1 and M1 transition densities and inclusion of E1 Coulomb excitation. The analysis separated pygmy dipole and M1 resonances in the forest at EPDR=9.15±0.18MeV with ΓPDR=2.91±0.64MeV and at EM1=9.53±0.06MeV with ΓM1=2.70±0.17MeV in the Lorentzian function, respectively. The B(E1)↑ value for pygmy dipole resonance over 7-11 MeV is 0.75±0.08e2fm2, which corresponds to 2.1±0.2% of the Thomas-Reiche-Kuhn sum rule.
Induction magnetometer for the RESONANCE project - parameters analysis
NASA Astrophysics Data System (ADS)
Pronenko, Vira; Santolik, Ondrej; Mogilevsky, Mihail; Dudkin, Denis; Jannet, Guillaume; Kolmasova, Ivana; Lan, Radek; Uhlir, Ludek
2013-04-01
The RESONANCE experiment focuses on the study of the processes in the inner magnetosphere of our planet. The objectives of the project include the investigation of interactions between waves and particles, and monitoring of the large-scale changes in the magnetosphere associated with geomagnetic activity and magnetic storms. The study of magnetic fields is of prime importance for RESONANCE project, taking into account that the special appeal of this mission is that four spacecrafts will be simultaneously launched at the specially designed path - the so-called "magnetosynchronous orbit" - when all the four spacecrafts will be some enough long time within the sole magnetic line. Thanks to its unique orbital configuration and instrumental composition, the RESONANCE project gives best opportunity for study of elongated structures in the magnetosphere of the Earth. The AC magnetic field will be measured by the three-component induction coil magnetometer LEMI-606, developed for the study of magnetic field fluctuations in space conditions in the frequency band 1-20000 Hz. It is known that the plasma parameters vary rapidly in space and time, so in the case of simultaneous measurements at four points special demand of high temporal resolution and low measurement error must be provided. To this, the identity of the parameters of all four devices that will be installed and operating simultaneously on all satellites becomes the major requirement. These all requirements were taken into account at the development of the LEMI-606 magnetometers. Another feature of these magnetometers is strongly nonsymmetric construction which is due to the general satellite design. Such an arrangement of the magnetometers leads to the increase of their cross-talk and nonorthogonality. The influence of the magnetometer construction on its parameters is analyzed. A comparison of the magnetometers parameters of symmetric and nonsymmetric design is carried out and experimental results are presented.
Darvishmanesh, Siavash; Vanneste, Johan; Tocci, Elena; Jansen, Johannes Carolus; Jansen, John; Tasselli, Franco; Tasseli, Franco; Degrève, Jan; Drioli, Enrico; Van der Bruggen, Bart
2011-12-15
Growing interest in nanofiltration for solvent purification requires a fundamental understanding of the physicochemical mechanisms of solute retention in organic solvent nanofiltration. In this study, the retention of a similar series of azo dyes with approximately similar molar mass (around 350 Da) by four nanofiltration membranes was studied. The membranes used are commercially available polymeric nanofiltration membranes with molecular weight cutoff between 150 and 300 Da (DuraMem150, StarMem122, NF270 and Desal-Dk). In order to correlate the retention with the size of the molecules, which is assumed to be one of the main factors that determines the retention, use was made of different parameters for the molecular size: molar mass, the Stokes diameter, the equivalent molar diameter, and the cavity surface in methanol and ethanol. All parameters were calculated by using molecular dynamics simulations. For each size parameter, the correlation with retention in nanofiltration experiments was calculated. For the StarMem122 membrane, zero retentions were observed due to the swelling of the membrane and pore size enlargement in methanol and ethanol. For the three other membranes, a fairly good correlation of the retention with the size could only be observed if the size difference between compounds is sufficiently large. Two other factors were studied by using molecular dynamics, i.e., the polarity of the molecule and the electron density of the molecule. The importance of these factors depends on the structure of the molecule as well as the functional groups of the polymer. A very good correlation has been observed for retention of dyes versus their dipole moment. Finally, the effect of solubility parameters of dyes on their retention did not show any significant effect.
sup 56 Fe and sup 60 Ni resonance parameters
Perey, C.M.; Perey, F.G.; Harvey, J.A.; Hill, N.W.; Larson, N.M.
1991-01-01
High-resolution neutron transmission and differential elastic-scattering measurements were made for a {sup 56}Fe-enriched iron target at the Oak Ridge Electron Linear Accelerator (ORELA). A natural iron target was used for transmission measurements below 160 keV. The data were analyzed from 5 to 850 keV. Parameters were obtained for 33 {ell} = 0 and 242 {ell} > 0 resonances. New {sup 6}Li-glass transmission data were acquired for two {sup 60}Ni-enriched sample thicknesses. The neutron width for the 2.253-keV resonance was determined to be 59.3 {plus minus} 0.6 meV and the radiation width 553 {plus minus} 50 meV. 9 refs., 3 figs., 2 tabs.
Parametrizations of the 21-cm global signal and parameter estimation from single-dipole experiments
NASA Astrophysics Data System (ADS)
Harker, Geraint J. A.; Mirocha, Jordan; Burns, Jack O.; Pritchard, Jonathan R.
2016-02-01
One approach to extracting the global 21-cm signal from total-power measurements at low radio frequencies is to parametrize the different contributions to the data and then fit for these parameters. We examine parametrizations of the 21-cm signal itself, and propose one based on modelling the Ly α background, intergalactic medium temperature and hydrogen ionized fraction using tanh functions. This captures the shape of the signal from a physical modelling code better than an earlier parametrization based on interpolating between maxima and minima of the signal, and imposes a greater level of physical plausibility. This allows less biased constraints on the turning points of the signal, even though these are not explicitly fit for. Biases can also be alleviated by discarding information which is less robustly described by the parametrization, for example by ignoring detailed shape information coming from the covariances between turning points or from the high-frequency parts of the signal, or by marginalizing over the high-frequency parts of the signal by fitting a more complex foreground model. The fits are sufficiently accurate to be usable for experiments gathering 1000 h of data, though in this case it may be important to choose observing windows which do not include the brightest areas of the foregrounds. Our assumption of pointed, single-antenna observations and very broad-band fitting makes these results particularly applicable to experiments such as the Dark Ages Radio Explorer, which would study the global 21-cm signal from the clean environment of a low lunar orbit, taking data from the far side.
Nonlinear Parameter Identification of a Resonant Electrostatic MEMS Actuator.
Al-Ghamdi, Majed S; Alneamy, Ayman M; Park, Sangtak; Li, Beichen; Khater, Mahmoud E; Abdel-Rahman, Eihab M; Heppler, Glenn R; Yavuz, Mustafa
2017-05-13
We experimentally investigate the primary superharmonic of order two and subharmonic of order one-half resonances of an electrostatic MEMS actuator under direct excitation. We identify the parameters of a one degree of freedom (1-DOF) generalized Duffing oscillator model representing it. The experiments were conducted in soft vacuum to reduce squeeze-film damping, and the actuator response was measured optically using a laser vibrometer. The predictions of the identified model were found to be in close agreement with the experimental results. We also identified the noise spectral density of process (actuation voltage) and measurement noise.
Effective parameters for periodic photonic structures of resonant elements.
Tserkezis, C
2009-04-15
We report on the effective electromagnetic parameters of metamaterials consisting of resonant building units, through systematic full-electrodynamic calculations by the layer-multiple-scattering method on a model system: a photonic crystal of metallic nanoshells. The results obtained by the S-matrix retrieval procedure for single- and multi-layer slabs of ordered arrays of such nanoshells are analysed in conjunction with the complex band structure of the corresponding infinite crystal and the Maxwell-Garnett effective-medium approximation. We discuss conditions that must be fulfilled in order for an effective-medium description of a metamaterial to be valid and explain artefacts which often occur in numerical calculations of the effective parameters. In particular, we propose a method to resolve ambiguities in the determination of the effective refractive index, which become prominent for thick slabs, based on the complex band structure of the infinite crystal.
NASA Astrophysics Data System (ADS)
KoÁak, H.; Dahong, Z.; Yildirim, A.
2011-02-01
An analytical expression is proposed to the Kirkwood-Fröhlich dipole orientation correlation parameter g. This parameter, which has been considered as a relevant guide to understanding the structuredness of supercritical fluids, had been always determined numerically. The advantage of the used protocol: the BPES, is to yield continuous and integrable expressions which can be easily incorporated in analytical models. The results have been compared to several precedent studies.
NASA Astrophysics Data System (ADS)
Chugunov, Yu. V.; Shirokov, E. A.
2016-05-01
The paper discusses issues related to the radiation and reception of quasi-electrostatic waves by short antennas in resonance conditions (in the whistler range) in magnetized plasma. First, the response of the receiving antenna on the incident field of slow quasipotential waves is analyzed. It made it possible to explain in detail the results of the two-point rocket experiment OEDIPUS-C in the Earth's ionosphere. Second, the problem of the charge distribution along the short transmission (reception) dipole antenna is considered. The corresponding integral equation is obtained and solved analytically. The impedance of the antenna is found. It is shown that in the majority of cases, charge distribution along the dipole length can be considered constant.
Buchner, H; Adams, L; Knepper, A; Rüger, R; Laborde, G; Gilsbach, J M; Ludwig, I; Reul, J; Scherg, M
1994-05-01
Surgery of lesions within or close to the central area of the brain always carries the risk of iatrogenic motor or sensory deficits. Functional localization by means of intraoperative direct stimulation of the motor area or by recording somatosensory evoked potentials (SSEP's) from the surface of the somatosensory cortex is believed to reduce the operative risk. The authors introduce the combination of dipole source analysis of scalp-recorded SSEP's with three-dimensional (3-D) magnetic resonance (MR) imaging as a tool for preoperative localization of the central sulcus. This provides information on both functional and structural localization for preoperative planning. Four repeated measurements of right and left median nerve SSEP's were obtained from 20 subjects. Dipole source analysis showed a retest reliability of the 3-D localization error of 2.9 +/- 2.0 mm. Compared to the MR evaluation, dipole source analysis was found to mark the central sulcus within 3 mm for 15 conditions (subjects x side of stimulation), while the 3-D MR measurement was accurate to within 6 mm for 10 conditions and 9 mm for 14 conditions. Dipole locations were confirmed in six patients who underwent surgery of the central region. With respect to this application, dipole source analysis combined with 3-D MR imaging appears to be a valuable tool for preoperative functional localization. The accuracy in localization will be further improved when realistic head models become available that can take into account individual head geometry. Further development of the proposed new method holds promise that evoked potentials and electroencephalography will gain greater use in presurgical functional localization.
NASA Astrophysics Data System (ADS)
Roca-Maza, X.; Cao, Li-Gang; Colò, G.; Sagawa, H.
2016-10-01
We have examined within a fully self-consistent theoretical framework the energy difference between the anti-analog giant dipole resonance (AGDR) and the isobaric analog state (IAS), EAGDR-EIAS , as an indicator of the neutron skin and of the density behavior of the symmetry energy. We have improved two specific points in our HF+RPA calculations: (1) the exchange term of the two-body Coulomb interaction is treated exactly without Slater approximation; and (2) the two-parameters spin-orbit interaction is treated in a consistent way within the energy density functional theory. The estimated values for the neutron skin in 208Pb and the slope parameter of symmetry energy are compared with previous analysis available in the literature.
Comments on extracting the resonance strength parameter from yield data
Croft, Stephen; Favalli, Andrea
2015-06-23
The F(α,n) reaction is the focus of on-going research in part because it is an important source of neutrons in the nuclear fuel cycle which can be exploited to assay nuclear materials, especially uranium in the form of UF6. At the present time there remains some considerable uncertainty (of the order of ± 20%) in the thick target integrated over angle (α,n) yield from 19F (100% natural abundance) and its compounds as discussed. An important thin target cross-section measurement is that of Wrean and Kavanagh who explore the region from below threshold (2.36 MeV) to approximately 3.1 MeV with finemore » energy resolution. Integration of their cross-section data over the slowing down history of a stopping α-particle allows the thick target yield to be calculated for incident energies up to 3.1 MeV. This trend can then be combined with data from other sources to obtain a thick target yield curve over the wider range of interest to the fuel cycle (roughly threshold to 10 MeV to include all relevant α-emitters). To estimate the thickness of the CaF2 target they used, Wrean and Kavanagh separately measured the integrated yield of the 6.129 MeV γ-rays from the resonance at 340.5 keV (laboratory α-particle kinetic energy) in the 19F(p,αγ) reaction. To interpret the data they adopted a resonance strength parameter of (22.3 ± 0.8) eV based on a determination by Becker et al. The value and its uncertainty directly affects the thickness estimate and the extracted (α,n) cross-section values. In their citation to Becker et al's work, Wrean and Kavanagh comment that they did not make use of an alternative value of (23.7±1.0) eV reported by Croft because they were unable to reproduce the value from the data given in that paper. The value they calculated for the resonance strength from the thick target yield given by Croft was 21.4 eV. The purpose of this communication is to revisit the paper by Croft published in this journal and specifically to explain the origin of
Comments on extracting the resonance strength parameter from yield data
NASA Astrophysics Data System (ADS)
Croft, Stephen; Favalli, Andrea
2015-10-01
The F(α,n) reaction is the focus of on-going research in part because it is an important source of neutrons in the nuclear fuel cycle which can be exploited to assay nuclear materials, especially uranium in the form of UF6 [1,2]. At the present time there remains some considerable uncertainty (of the order of ±20%) in the thick target integrated over angle (α,n) yield from 19F (100% natural abundance) and its compounds as discussed in [3,4]. An important thin target cross-section measurement is that of Wrean and Kavanagh [5] who explore the region from below threshold (2.36 MeV) to approximately 3.1 MeV with fine energy resolution. Integration of their cross-section data over the slowing down history of a stopping α-particle allows the thick target yield to be calculated for incident energies up to 3.1 MeV. This trend can then be combined with data from other sources to obtain a thick target yield curve over the wider range of interest to the fuel cycle (roughly threshold to 10 MeV to include all relevant α-emitters). To estimate the thickness of the CaF2 target they used, Wrean and Kavanagh separately measured the integrated yield of the 6.129 MeV γ-rays from the resonance at 340.5 keV (laboratory α-particle kinetic energy) in the 19F(p,αγ) reaction. To interpret the data they adopted a resonance strength parameter of (22.3±0.8) eV based on a determination by Becker et al [6]. The value and its uncertainty directly affects the thickness estimate and the extracted (α,n) cross-section values. In their citation to Becker et al's work, Wrean and Kavanagh comment that they did not make use of an alternative value of (23.7±1.0) eV reported by Croft [7] because they were unable to reproduce the value from the data given in that paper. The value they calculated for the resonance strength from the thick target yield given by Croft was 21.4 eV. The purpose of this communication is to revisit the paper by Croft published in this journal and specifically to
Comments on extracting the resonance strength parameter from yield data
Croft, Stephen; Favalli, Andrea
2015-06-23
The F(α,n) reaction is the focus of on-going research in part because it is an important source of neutrons in the nuclear fuel cycle which can be exploited to assay nuclear materials, especially uranium in the form of UF_{6}. At the present time there remains some considerable uncertainty (of the order of ± 20%) in the thick target integrated over angle (α,n) yield from ^{19}F (100% natural abundance) and its compounds as discussed. An important thin target cross-section measurement is that of Wrean and Kavanagh who explore the region from below threshold (2.36 MeV) to approximately 3.1 MeV with fine energy resolution. Integration of their cross-section data over the slowing down history of a stopping α-particle allows the thick target yield to be calculated for incident energies up to 3.1 MeV. This trend can then be combined with data from other sources to obtain a thick target yield curve over the wider range of interest to the fuel cycle (roughly threshold to 10 MeV to include all relevant α-emitters). To estimate the thickness of the CaF_{2} target they used, Wrean and Kavanagh separately measured the integrated yield of the 6.129 MeV γ-rays from the resonance at 340.5 keV (laboratory α-particle kinetic energy) in the ^{19}F(p,αγ) reaction. To interpret the data they adopted a resonance strength parameter of (22.3 ± 0.8) eV based on a determination by Becker et al. The value and its uncertainty directly affects the thickness estimate and the extracted (α,n) cross-section values. In their citation to Becker et al's work, Wrean and Kavanagh comment that they did not make use of an alternative value of (23.7±1.0) eV reported by Croft because they were unable to reproduce the value from the data given in that paper. The value they calculated for the resonance strength from the thick target yield given by Croft was 21.4 eV. The purpose of this communication is to revisit the paper by Croft published in this journal and
NASA Astrophysics Data System (ADS)
Kumar, Sanjay; Jain, Sapan K.; Rastogi, Ramesh C.
2001-02-01
The electronic absorption and fluorescence spectra of some biologically active natural flavones have been recorded at room temperature (298 K) in solvents of different polarities. The effects of the solvents upon the spectral properties are discussed. Difference in fluorescence intensity of flavones has been explained on the basis of intersystem crossing and degree of non-planarity calculated theoretically using Austin Model 1 (AM1) method. Excited-state dipole moments have been determined using the solvatochromic method based on the microscopic solvent polarity parameter, ETN. A reasonable agreement has been observed between experimental and AM1 calculated dipole moment changes. Our results are found to be quite reliable in view of the fact that the correlation of the solvatochromic Stokes shifts with microscopic solvent polarity parameter, ETN is superior to that obtained using bulk solvent polarity functions for all the systems studied here.
NASA Astrophysics Data System (ADS)
Scheck, M.; Ponomarev, V. Yu.; Fritzsche, M.; Joubert, J.; Aumann, T.; Beller, J.; Isaak, J.; Kelley, J. H.; Kwan, E.; Pietralla, N.; Raut, R.; Romig, C.; Rusev, G.; Savran, D.; Schorrenberger, L.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Zilges, A.; Zweidinger, M.
2013-10-01
Background: Within the last decade, below the giant dipole resonance the existence of a concentration of additional electric dipole strength has been established. This accumulation of low-lying E1 strength is commonly referred to as pygmy dipole resonance (PDR).Purpose: The photoresponse of 60Ni has been investigated experimentally and theoretically to test the evolution of the PDR in a nucleus with only a small neutron excess. Furthermore, the isoscalar and isovector M1 resonances were investigated.Method: Spin-1 states were excited by exploiting the (γ,γ') nuclear resonance fluorescence technique with unpolarized continuous bremsstrahlung as well as with fully linearly polarized, quasimonochromatic, Compton-backscattered laser photons in the entrance channel of the reaction.Results: Up to 10 MeV a detailed picture of J=1 levels was obtained. For the preponderant number of the individual levels spin and parity were firmly assigned. Furthermore, branching ratios, transition widths, and reduced B(E1) or B(M1) excitation probability were calculated from the measured scattering cross sections. A comparison with theoretical results obtained within the quasiparticle phonon model allows an insight into the microscopic structure of the observed states.Conclusions: Below 10 MeV the directly observed E1 strength [∑B(E1)↑=(153.8±9.5) e2(fm)2] exhausts 0.5% of the Thomas-Reiche-Kuhn sum rule. This value increases to 0.8% of the sum rule [∑B(E1)↑=(250.9±31.1) e2(fm)2] when indirectly observed branches to lower-lying levels are considered. Two accumulations of M1 excited spin-1 states near 8 and 9 MeV excitation energy are identified as isoscalar and isovector M1 resonances dominated by proton and neutron f7/2→f5/2 spin-flip excitations. The B(M1)↑ strength of these structures accumulates to 3.94(27)μN2.
NASA Astrophysics Data System (ADS)
Chou Chau, Yuan-Fong; Lim, Chee Ming; Lee, Chuanyo; Huang, Hung Ji; Lin, Chun-Ting; Kumara, N. T. R. N.; Yoong, Voo Nyuk; Chiang, Hai-Pang
2016-09-01
Tunable surface plasmon resonance (SPR) and dipole cavity plasmon modes of the scattering cross section (SCS) spectra on the single solid-gold/gold-shell nanorod have been numerically investigated by using the finite element method. Various effects, such as the influence of SCS spectra under x- and y-polarizations on the surface of the single solid-gold/gold-shell nanorod, are discussed in detail. With the single gold-shell nanorod, one can independently tune the relative SCS spectrum width by controlling the rod length and rod diameter, and the surface scattering by varying the shell thickness and polarization direction, as well as the dipole peak energy. These behaviors are consistent with the properties of localized SPRs and offer a way to optically control and produce selected emission wavelengths from the single solid-gold/gold-shell nanorod. The electric field and magnetic distributions provide us a qualitative idea of the geometrical properties of the single solid-gold/gold-shell nanorod on plasmon resonance.
Chou Chau, Yuan-Fong Lim, Chee Ming; Kumara, N. T. R. N.; Yoong, Voo Nyuk; Lee, Chuanyo; Huang, Hung Ji; Lin, Chun-Ting; Chiang, Hai-Pang
2016-09-07
Tunable surface plasmon resonance (SPR) and dipole cavity plasmon modes of the scattering cross section (SCS) spectra on the single solid-gold/gold-shell nanorod have been numerically investigated by using the finite element method. Various effects, such as the influence of SCS spectra under x- and y-polarizations on the surface of the single solid-gold/gold-shell nanorod, are discussed in detail. With the single gold-shell nanorod, one can independently tune the relative SCS spectrum width by controlling the rod length and rod diameter, and the surface scattering by varying the shell thickness and polarization direction, as well as the dipole peak energy. These behaviors are consistent with the properties of localized SPRs and offer a way to optically control and produce selected emission wavelengths from the single solid-gold/gold-shell nanorod. The electric field and magnetic distributions provide us a qualitative idea of the geometrical properties of the single solid-gold/gold-shell nanorod on plasmon resonance.
Miyamoto, R.; Kopp, S.E.; Jansson, A.; Syphers, M.J.; /Fermilab
2007-06-01
The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.
NASA Technical Reports Server (NTRS)
Brown, J. M.; Curl, R. F.; Evenson, K. M.
1984-01-01
The far-infrared laser magnetic resonance spectrum of the SiH radical in the v = O level of its X2Pi state has been recorded. The signals are rather weak. The molecules were generated in the reaction between fluorine atoms and SiH4. Rotational transitions have been detected in both 2Pi1/2 and 2Pi3/2 spin components but no fine structure transitions between the spin components were observed. Proton hyperfine splittings were resolved on some lines. The measurements have been analyzed, subjected to a least-squares fit using an effective Hamiltonian, and the appropriate molecular parameters determined. The weakness of the spectrum and the failure of attempts to power saturate favorable lines are both consistent with a small value for the electric dipole moment for SiH.
Markov Chain Monte Carlo Used in Parameter Inference of Magnetic Resonance Spectra
Hock, Kiel; Earle, Keith
2016-02-06
In this paper, we use Boltzmann statistics and the maximum likelihood distribution derived from Bayes’ Theorem to infer parameter values for a Pake Doublet Spectrum, a lineshape of historical significance and contemporary relevance for determining distances between interacting magnetic dipoles. A Metropolis Hastings Markov Chain Monte Carlo algorithm is implemented and designed to find the optimum parameter set and to estimate parameter uncertainties. In conclusion, the posterior distribution allows us to define a metric on parameter space that induces a geometry with negative curvature that affects the parameter uncertainty estimates, particularly for spectra with low signal to noise.
Markov Chain Monte Carlo Used in Parameter Inference of Magnetic Resonance Spectra
Hock, Kiel; Earle, Keith
2016-02-06
In this paper, we use Boltzmann statistics and the maximum likelihood distribution derived from Bayes’ Theorem to infer parameter values for a Pake Doublet Spectrum, a lineshape of historical significance and contemporary relevance for determining distances between interacting magnetic dipoles. A Metropolis Hastings Markov Chain Monte Carlo algorithm is implemented and designed to find the optimum parameter set and to estimate parameter uncertainties. In conclusion, the posterior distribution allows us to define a metric on parameter space that induces a geometry with negative curvature that affects the parameter uncertainty estimates, particularly for spectra with low signal to noise.
Evaluation of 238U Resonance Parameters from 0 to 20 keV
Derrien, H.; Leal, L.C.; Larson, N.; Courcelle, A.; Santamarina, A.
2005-05-24
The neutron resonance parameters of 238U were obtained in the energy range 0 to 20 keV from a sequential SAMMY analysis of the most recent high-resolution neutron transmission and neutron capture cross-section measurements. Special care was taken in the analysis of the lowest s-wave resonances leading to resonance parameters slightly different from those of ENDF/B-VI (Moxon-Sowerby resonance parameters). The resolved-resonance range was extended to 20 keV, taking advantage of the high-resolution neutron transmission data of Harvey and neutron capture data of Macklin et al. Preliminary integral tests were performed with the new resonance parameters; thermal low-enriched benchmark calculations show an improvement of the keff prediction, mainly due to a 1.5% decrease of the capture cross section at 0.0253 eV and about a 0.4% decrease of the effective shielded resonance capture integral.
Pygmy Dipole Strength and Neutron Skins in Exotic Nuclei
NASA Astrophysics Data System (ADS)
Klimkiewicz, A.; Paar, N.; Adrich, P.; Fallot, M.; Boretzky, K.; Aumann, T.; Cortina-Gil, D.; Pramanik, U. Datta; Elze, Th. W.; Emling, H.; Geissel, H.; Hellström, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Nociforo, C.; Palit, R.; Simon, H.; Surówka, G.; Sümmerer, K.; Vretenar, D.; Waluś, W.
2008-05-01
Dipole strength distributions were determined for the neutron-rich nuclei 129-132Sn and 133,134Sb from electromagnetic excitation in an experiment using the FRS-LAND setup. For all nuclei, a sizeable fraction of ``pygmy'' dipole strength at excitation energies well below the giant dipole resonance was observed. The integrated low-lying dipole strength of the nuclei with low neutron separation energies can be compared to results for stable nuclei (e.g. N = 82 isotopes) determined for the energy regime of 5-9 MeV. A clear increase of the dipole strength with increasing asymmetry of the nuclei is observed. Comparing the ratio of the low-lying dipole over the giant dipole strength to recent relativistic mean field calculations, values for the parameters a4 and p0 of the symmetry energy and for the neutron skin thickness are derived. Averaged over 130Sn and 132Sn we extract a4 = 31.8+/-1.3 MeV and p0 = 2.2+/-0.5 MeV/fm3. The neutron skin sizes are determined to Rn-Rp = 0.23+/-0.03 fm and 0.24+/-0.03 fm for 130Sn and 132Sn, respectively. For 208Pb a neutron skin thickness of Rn-Rp = 0.18+/-0.035 fm follows, when applying the same method and using earlier published experimental findings on the dipole strength.
NASA Technical Reports Server (NTRS)
Brown, J. M.; Evenson, K. M.; Sears, T. J.
1985-01-01
The GeH radical has been detected in its ground 2 Pi state in the gas phase reaction of fluorine atoms with GeH4 by laser magnetic resonance techniques. Rotational transitions within both 2 Pi 1/2 and 2 Pi 3/2 manifolds have been observed at far-infrared wavelengths and rotational transitions between the two fine structure components have been detected at infrared wavelengths (10 microns). Signals have been observed for all five naturally occurring isotopes of germanium. Nuclear hyperfine structure for H-1 and Ge-73 has also been observed. The data for the dominant isotope (/Ge-74/H) have been fitted to within experimental error by an effective Hamiltonian to give a set of molecular parameters for the X 2 Pi state which is very nearly complete. In addition, the dipole moment of GeH in its ground state has been estimated from the relative intensities of electric and magnetic dipole transitions in the 10 micron spectrum to be 1.24(+ or - 0.10) D.
Dixit, Karuna; Pande, Ajay; Pande, Jayanti; Sarma, Siddhartha P
2016-06-07
A hallmark of the crystallin proteins is their exceptionally high solubility, which is vital for maintaining the high refractive index of the eye lens. Human γC-crystallin is a major γ-crystallin whose mutant forms are associated with congenital cataracts but whose three-dimensional structure is not known. An earlier study of a homology model concluded that human γC-crystallin has low intrinsic solubility, mainly because of the atypical magnitude and fluctuations of its dipole moment. On the contrary, the high-resolution tertiary structure of human γC-crystallin determined here shows unequivocally that it is a highly soluble, monomeric molecule in solution. Notable differences between the orientations and interactions of several side chains are observed upon comparison to those in the model. No evidence of the pivotal role ascribed to the effect of dipole moment on protein solubility was found. The nuclear magnetic resonance structure should facilitate a comprehensive understanding of the deleterious effects of cataract-associated mutations in human γC-crystallin.
NASA Astrophysics Data System (ADS)
Ponciano-Ojeda, F.; Hernández-Gómez, S.; López-Hernández, O.; Mojica-Casique, C.; Colín-Rodríguez, R.; Ramírez-Martínez, F.; Flores-Mijangos, J.; Sahagún, D.; Jáuregui, R.; Jiménez-Mier, J.
2015-10-01
Direct evidence of excitation of the 5 p3 /2→6 p3 /2 electric-dipole-forbidden transition in atomic rubidium is presented. The experiments were performed in a room-temperature rubidium cell with continuous-wave external cavity diode lasers. Optical-optical double-resonance spectroscopy with counterpropagating beams allows the detection of the nondipole transition free of Doppler broadening. The 5 p3 /2 state is prepared by excitation with a laser locked to the maximum F cyclic transition of the D2 line, and the forbidden transition is produced by excitation with a 911 nm laser. Production of the forbidden transition is monitored by detection of the 420 nm fluorescence that results from decay of the 6 p3 /2 state. Spectra with three narrow lines (≈13 MHz FWHM) with the characteristic F -1 , F , and F +1 splitting of the 6 p3 /2 hyperfine structure in both rubidium isotopes were obtained. The results are in very good agreement with a direct calculation that takes into account the 5 s →5 p3 /2 preparation dynamics, the 5 p3 /2→6 p3 /2 nondipole excitation geometry, and the 6 p3 /2→5 s1 /2 decay. The comparison also shows that the electric-dipole-forbidden transition is a very sensitive probe of the preparation dynamics.
NASA Astrophysics Data System (ADS)
Nord, A.; Schiller, A.; Eckert, T.; Beck, O.; Besserer, J.; von Brentano, P.; Fischer, R.; Herzberg, R.-D.; Jäger, D.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H. H.; Rittner, M.; Zilges, A.
1996-11-01
Nuclear resonance fluorescence experiments were performed on the rare earth nuclei 155Gd and 159Tb to study the fragmentation of the M1 scissors mode in odd deformed nuclei and to establish a kind of systematics. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.1 MeV) and high resolution Ge-γ spectrometers detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. The results are compared to those observed recently for the neighboring odd nuclei 161,163Dy and 157Gd. Whereas in the odd Dy isotopes the dipole strength is rather concentrated, both Gd isotopes show a strong fragmentation of the strength into about 25 (155Gd) and 90 transitions (157Gd) in the energy range 2-4 MeV. The nucleus 159Tb linking the odd Dy and Gd isotopes exhibits an intermediate strength fragmentation. In general the observed total strength in the odd nuclei is reduced by a factor of 2-3 as compared to their neighboring even-even isotopes. The different fragmentation behavior of the dipole strengths in the odd Dy and Gd isotopes is unexplained up to now.
Resonance in a weakly nonlinear system with slowly varying parameters
NASA Astrophysics Data System (ADS)
Kevorkian, J.
1980-02-01
Multiple-variable expansion procedures appropriate for nonlinear systems in resonance are surveyed by the use of the model of two coupled weakly nonlinear oscillators with either constant or slowly varying frequencies. In the autonomous problem it is shown that an n-variable expansion (where n depends on the order of accuracy desired) yields uniformly valid results. The problem of passage through resonance for the nonautonomous problem is also considered and the solution is described by constructing a sequence of three expansions. The solution before resonance is developed as a generalized multiple-variable expansion and is matched with an inner expansion valid during resonance. This latter is then matched with a postresonance solution and determines it completely. Numerical integrations are used to substantiate the theoretical results. The dominant effect of passage through resonance is shown to be the excitation of a higher-order oscillation beyond resonance. Contrary to the claim in a recent work, the total action of the system does not remain constant if one accounts for the leading perturbation terms in the postresonance solution. Instead, the total action goes from one constant value to another.
Utsunomiya, H.; Kamata, M.; Kondo, T.; Itoh, O.; Akimune, H.; Yamagata, T.; Goriely, S.; Toyokawa, H.; Lui, Y.-W.; Hilaire, S.; Koning, A. J.
2009-11-15
Photoneutron cross sections were measured for {sup 117}Sn and {sup 116}Sn near the neutron thresholds at 6.94 and 9.56 MeV, respectively, with quasi-monochromatic laser-Compton scattering {gamma} rays. The {sup 117}Sn cross section, which is strongly enhanced near the low threshold, provides evidence for the presence of extra {gamma} strength in the low-energy tail of the giant dipole resonance. A coherent analysis of the photoneutron data for {sup 117}Sn together with the neutron capture on {sup 116}Sn shows that the {gamma}-ray strength function is balanced in the photoneutron and neutron capture channels in terms of the microscopic Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation model of E1 strength combined with a pygmy E1 resonance at 8.5 MeV. The high-energy part of the pygmy resonance is also suggested in the photoneutron cross section for {sup 116}Sn.
Verbitsky, S. S.; Lapic, A.M. Ratner, B. S.; Rusakov, A. V.; Tikanov, M. A.; Tulupov, B. A.; Tzelebrovsky, A. N.
2009-03-15
The cross sections for the emission of fast neutrons ({epsilon}{sub n} > 3.7 MeV) in the reactions {sup 52}Cr({gamma}, n){sup 51}Cr and {sup 51}V({gamma}, n){sup 50}V at incident-photon energies in the range between 16.0 and 25.8 MeV were studied. The neutron energy spectra were measured at the bremsstrahlung-photon endpoint energies of 18.5, 21.0, and 23.0 MeV for the {sup 52}Cr and {sup 51}V nuclei and at the bremsstrahlung-photon energy of 25.5 MeV for the {sup 51}V nucleus. Special features of giant-dipole-resonance decay that are associated with the existence of a structure in photoneutron cross sections and spectra are discussed.
Barlini, S.; Kravchuk, V. L.; Gramegna, F.; Lanchais, A.; Mastinu, P. F.; Wieland, O.; Bracco, A.; Airoldi, A.; Benzoni, G.; Blasi, N.; Brambilla, S.; Camera, F.; Leoni, S.; Million, B.; Moroni, A.; Sacchi, R.; Brekiesz, M.; Kmiecik, M.; Maj, A.; Bruno, M.
2006-08-14
Recent measurements have been performed at the National Laboratoty of Legnaro using mass-symmetric (400, 500 MeV 64Ni + 68Zn) and mass-asymmetric (250 MeV 16O + 116Sn) entrance channel reactions to form {sup 132}Ce compound nucleus at different excitation energies (E*=150, 200 and 200 MeV, respectively). The decay of the composite system has been followed studying the {gamma}-rays and Light Charged Particles (LCP) spectra emitted in coincidence with the Evaporation Residues (ER). In this way the emission mechanism of the LCP, depending on the mass-asymmetry at the entrance channel and on the projectile energy, and the results of the Full Width Half-Maximum (FWHM) of the Giant Dipole Resonance as a function of the nuclear temperature have been studied.
Gondek, E; Nizioł, J; Danel, A; Szlachcic, P; Pluciński, K; Sanetra, J; Kityk, I V
2010-05-01
Absorption, photo- and electroluminescence spectra of some trityl substituted 1H-pyrazolo[3,4-b]quinolines derivatives (methyl- and phenyl substituted) and fabrication of the single layered organic light emitting diodes are reported. The bulky trityl substituent was introduced to prevent aggregation and crystallization of the dopant in polymer matrix. Role of ground state dipole moments in the observed red Stokes shift, electroluminescent features and photocarrier transport is explored. The maximally achieved brightness about 50Cd/m(2) is observed in the spectral range extending from 443nm up to 462nm. The voltage threshold was varied from 7.8V up to 10V. The brightness-current dependences show an existence of at least two types of carrier injections.
Average Description of Dipole Gamma Transitions in Hot Atomic Nuclei
NASA Astrophysics Data System (ADS)
Plujko, V. A.; Gorbachenko, O. M.; Rovenskykh, E. P.; Zheltonozhskii, V. A.
2014-04-01
A new version of the modified Lorentzian approach for radiative strength function is proposed. It is based on renewed systematics for giant dipole resonance (GDR) parameters. The gamma-decay strength functions are calculated using new GDR parameters and compared with experimental data. It is demonstrated that closed-form approaches with energy-dependent width of the gamma strength, as a rule, provide a reliable simple method for description of gamma-decay processes.
NASA Astrophysics Data System (ADS)
Konno, Kohkichi; Nagasawa, Tomoaki; Takahashi, Rohta
2017-10-01
We discuss the scattering of a quantum particle by two independent successive point interactions in one dimension. The parameter space for two point interactions is given by U(2) × U(2) , which is described by eight real parameters. We perform an analysis of perfect resonant transmission on the whole parameter space. By investigating the effects of the two point interactions on the scattering matrix of plane wave, we find the condition under which perfect resonant transmission occurs. We also provide the physical interpretation of the resonance condition.
Effects of relevant parameters on the bandgaps of acoustic metamaterials with multi-resonators
NASA Astrophysics Data System (ADS)
Zhou, Xiaoqin; Wang, Jun; Wang, Rongqi; Lin, Jieqiong
2016-04-01
Locally resonant acoustic metamaterials with multi-resonators are generally regarded as a fine trend for managing the bandgaps, the different effects of relevant structural parameters on the bandgaps, which will be numerically investigated in this paper. A two-step homogenization method is extended to achieve the effective mass of multi-resonators metamaterial in the lattice system. As comparison, the dispersive wave propagation in lattice system and continuum model is studied. Then, the different effects of relevant parameters on the center frequencies and bandwidth of bandgaps are perfectly revealed, and the steady-state responses in the continuum models with purposed relevant parameters are additionally clarified. The related results can well confirm that the bandgaps exist around the undamped natural frequencies of internal resonators, and also their bandwidth can be efficiently controlled with the ensured center frequencies. Moreover, the design of purposed multi-resonators acoustic metamaterial in vibration control is presented and discussed by an example.
A Comsol analysis of packaging structures and parameters of quartz crystal resonators
NASA Astrophysics Data System (ADS)
Wang, Ji; Li, Lin; Ma, Tingfeng; Du, Jianke; Huang, Bin; Shen, Julian; Chao, Min-Chiang
2017-09-01
By nature, acoustic wave resonators are structurally dynamic components undergoing constant vibrations in the vicinity of resonant frequency at their functioning mode, which is definitely adversary with other components used in the same board and product. One particular concern in the design and packaging of acoustic wave resonators is that all packaging parameters and structures will cause changes of device performance in terms of frequency, circuit parameters, and thermal sensitivity, among others. We start with a complete finite element analysis model of a quartz crystal resonator with the consideration of structural complications including packaging, while the quartz crystal blank is analyzed with the Mindlin plate equations of five vibration modes for coupled thickness-shear vibrations. Other parts of structure are formulated with the three-dimensional theory of elasticity from Comsol. With this finite element model, many of the key features and parameters of the quartz crystal resonator are considered and a practical model and design process is established.
NASA Astrophysics Data System (ADS)
Chen, Disheng; Lander, Gary R.; Solomon, Glenn S.; Flagg, Edward B.
2017-01-01
Resonant photoluminescence excitation (RPLE) spectra of a neutral InGaAs quantum dot show unconventional line shapes that depend on the detection polarization. We characterize this phenomenon by performing polarization-dependent RPLE measurements and simulating the measured spectra with a three-level quantum model. The spectra are explained by interference between fields coherently scattered from the two fine structure split exciton states, and the measurements enable extraction of the steady-state coherence between the two exciton states.
Li, Xuefeng; Cao, Guangzhan; Liu, Hongjun
2014-04-15
Based on solving numerically the generalized nonlinear Langevin equation describing the nonlinear dynamics of stochastic resonance by Fourth-order Runge-Kutta method, an aperiodic stochastic resonance based on an optical bistable system is numerically investigated. The numerical results show that a parameter-tuning stochastic resonance system can be realized by choosing the appropriate optical bistable parameters, which performs well in reconstructing aperiodic signals from a very high level of noise background. The influences of optical bistable parameters on the stochastic resonance effect are numerically analyzed via cross-correlation, and a maximum cross-correlation gain of 8 is obtained by optimizing optical bistable parameters. This provides a prospective method for reconstructing noise-hidden weak signals in all-optical signal processing systems.
SAMDIST: A Computer Code for Calculating Statistical Distributions for R-Matrix Resonance Parameters
Leal, L.C.
1995-01-01
The: SAMDIST computer code has been developed to calculate distribution of resonance parameters of the Reich-Moore R-matrix type. The program assumes the parameters are in the format compatible with that of the multilevel R-matrix code SAMMY. SAMDIST calculates the energy-level spacing distribution, the resonance width distribution, and the long-range correlation of the energy levels. Results of these calculations are presented in both graphic and tabular forms.
Dipole-induced electromagnetic transparency.
Puthumpally-Joseph, Raiju; Sukharev, Maxim; Atabek, Osman; Charron, Eric
2014-10-17
We determine the optical response of a thin and dense layer of interacting quantum emitters. We show that, in such a dense system, the Lorentz redshift and the associated interaction broadening can be used to control the transmission and reflection spectra. In the presence of overlapping resonances, a dipole-induced electromagnetic transparency (DIET) regime, similar to electromagnetically induced transparency (EIT), may be achieved. DIET relies on destructive interference between the electromagnetic waves emitted by quantum emitters. Carefully tuning material parameters allows us to achieve narrow transmission windows in, otherwise, completely opaque media. We analyze in detail this coherent and collective effect using a generalized Lorentz model and show how it can be controlled. Several potential applications of the phenomenon, such as slow light, are proposed.
Cuny, Jérôme; Sykina, Kateryna; Fontaine, Bruno; Le Pollès, Laurent; Pickard, Chris J; Gautier, Régis
2011-11-21
Solid-state (95)Mo nuclear magnetic resonance (NMR) properties of molybdenum hexacarbonyl have been computed using density functional theory (DFT) based methods. Both quadrupolar coupling and chemical shift parameters were evaluated and compared with parameters of high precision determined using single-crystal (95)Mo NMR experiments. Within a molecular approach, the effects of major computational parameters, i.e. basis set, exchange-correlation functional, treatment of relativity, have been evaluated. Except for the isotropic parameter of both chemical shift and chemical shielding, computed NMR parameters are more sensitive to geometrical variations than computational details. Relativistic effects do not play a crucial part in the calculations of such parameters for the 4d transition metal, in particular isotropic chemical shift. Periodic DFT calculations were tackled to measure the influence of neighbouring molecules on the crystal structure. These effects have to be taken into account to compute accurate solid-state (95)Mo NMR parameters even for such an inorganic molecular compound.
Resonance Parameters of the Rho-Meson from Lattice QCD
Xu Feng, Karl Jansen, Dru Renner
2011-05-01
We perform a non-perturbative lattice calculation of the P-wave pion-pion scattering phase in the rho-meson decay channel using two flavors of maximally twisted mass fermions at pion masses ranging from 480 MeV to 290 MeV. Making use of finite-size methods, we evaluate the pion-pion scattering phase in the center-of-mass frame and two moving frames. Applying an effective range formula, we find a good description of our results for the scattering phase as a function of the energy covering the resonance region. This allows us to extract the rho-meson mass and decay width and to study their quark mass dependence.
NASA Astrophysics Data System (ADS)
Bray, Cédric; Cuisset, Arnaud; Hindle, Francis; Bocquet, Robin; Mouret, Gaël; Drouin, Brian J.
2017-03-01
Several previously unmeasured transitions of 12CH3D have been recorded by a terahertz photomixing continuous-wave spectrometer up to QR(10) branch at 2.5 THz. An improved set of rotational constants has been obtained utilizing a THz frequency metrology based on a frequency comb that achieved an averaged frequency position better than 150 kHz on more than fifty ground-state transitions. A detailed analysis of the measured line intensities was undertaken using the multispectrum fitting program and has resulted in a determination of new dipole moment parameters. Measurements at different pressures of the QR(7) transitions provide the first determination of self-broadening coefficients from pure rotational CH3D lines. The THz rotational measurements are consistent with IR rovibrational data but no significant vibrational dependence of self-broadening coefficient may be observed by comparison.
NASA Technical Reports Server (NTRS)
Omidvar, K.
1972-01-01
Derivation of expressions for the excitation cross section in the dipole approximation of the semiclassical impact parameter and the Born approximations, making use of a formula given by Menzel (1968, 1969) for the asymptotic expansion of the oscillator strength of the hydrogen-like atoms. When only the leading term in the asymptotic expansion is retained, the expression for the cross section becomes identical with the expression obtained by the method of the classical collision and correspondence principle given by Percival and Richards (1970). Comparisons are made between the Bethe coefficients obtained by the author and the Bethe coefficients of the Born approximation for transitions where the Born calculation is available. Satisfactory agreement is obtained only for n yields n + 1 transitions, where n is the principal quantum number of the excited state.
Spin dephasing in a magnetic dipole field.
Ziener, C H; Kampf, T; Reents, G; Schlemmer, H-P; Bauer, W R
2012-05-01
Transverse relaxation by dephasing in an inhomogeneous field is a general mechanism in physics, for example, in semiconductor physics, muon spectroscopy, or nuclear magnetic resonance. In magnetic resonance imaging the transverse relaxation provides information on the properties of several biological tissues. Since the dipole field is the most important part of the multipole expansion of the local inhomogeneous field, dephasing in a dipole field is highly important in relaxation theory. However, there have been no analytical solutions which describe the dephasing in a magnetic dipole field. In this work we give a complete analytical solution for the dephasing in a magnetic dipole field which is valid over the whole dynamic range.
Spin dephasing in a magnetic dipole field
NASA Astrophysics Data System (ADS)
Ziener, C. H.; Kampf, T.; Reents, G.; Schlemmer, H.-P.; Bauer, W. R.
2012-05-01
Transverse relaxation by dephasing in an inhomogeneous field is a general mechanism in physics, for example, in semiconductor physics, muon spectroscopy, or nuclear magnetic resonance. In magnetic resonance imaging the transverse relaxation provides information on the properties of several biological tissues. Since the dipole field is the most important part of the multipole expansion of the local inhomogeneous field, dephasing in a dipole field is highly important in relaxation theory. However, there have been no analytical solutions which describe the dephasing in a magnetic dipole field. In this work we give a complete analytical solution for the dephasing in a magnetic dipole field which is valid over the whole dynamic range.
Kumar, P T Krishna; Sekimoto, Hiroshi
2009-02-01
Covariance matrix elements depict the statistical and systematic uncertainties in reactor parameter measurements. All the efforts have so far been devoted only to minimise the statistical uncertainty by repeated measurements but the dominant systematic uncertainty has either been neglected or randomized. In recent years efforts has been devoted to simulate the resonance parameter uncertainty information through covariance matrices in code SAMMY. But, the code does not have any provision to check the reliability of the simulated covariance data. We propose a new approach called entropy based information theory to reduce the systematic uncertainty in the correlation matrix element so that resonance parameters with minimum systematic uncertainty can be modelled. We apply our information theory approach in generating the resonance parameters of (156)Gd with reduced systematic uncertainty and demonstrate the superiority of our technique over the principal component analysis method.
NASA Astrophysics Data System (ADS)
Protsenko, I. E.; Uskov, A. V.; Zaimidoroga, O. A.; Samoilov, V. N.; O'Reilly, E. P.
2005-06-01
A “dipole” laser is proposed consisting of a nanoparticle and a two-level system with population inversion. If the threshold conditions are fulfilled, the dipole interaction between the two-level system and the nanoparticle leads to coherent oscillations in the polarization of the particles, even in the absence of an external electromagnetic field. The emitted radiation has a dipolar distribution. It does not need an optical cavity, and has a very small volume, ˜0.1μm3 , which can be important for applications in microelectronics. Estimates of the threshold conditions are carried out for a dipole laser composed of a quantum dot and a silver nanoparticle.
Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium
G. Leinweber; J.A. Burke; H.D. Knox; N.J. Drindak; D.W. Mesh; W.T. Haines; R.V. Ballad; R.C. Block; R.E. Slovacek; C.J. Werner; M.J. Trbovich; D.P. Barry; T. Sato
2001-07-16
The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated
Dipole-dipole interaction between rubidium Rydberg atoms
Altiere, Emily; Fahey, Donald P.; Noel, Michael W.; Smith, Rachel J.; Carroll, Thomas J.
2011-11-15
Ultracold Rydberg atoms in a static electric field can exchange energy via the dipole-dipole interaction. The Stark effect shifts the energy levels of the atoms which tunes the energy exchange into resonance at specific values of the electric field (Foerster resonances). We excite rubidium atoms to Rydberg states by focusing either a 480 nm beam from a tunable dye laser or a pair of diode lasers into a magneto-optical trap. The trap lies at the center of a configuration of electrodes. We scan the electric field by controlling the voltage on the electrodes while measuring the fraction of atoms that interact. Dipole-dipole interaction spectra are presented for initially excited rubidium nd states for n=31 to 46 and for four different pairs of initially excited rubidium ns states. We also present the dipole-dipole interaction spectra for individual rubidium 32d (j, m{sub j}) fine structure levels that have been selectively excited. The data are compared to calculated spectra.
Dumbbell dipole model and its application in UXO discrimination
NASA Astrophysics Data System (ADS)
Sun, K.; O'Neill, K.; Barrowes, B. E.; Fernández, J. P.; Shubitidze, F.; Shamatava, I.; Paulsen, K. D.
2006-05-01
Electromagnetic Induction (EMI) is one of the most promising techniques for UXO discrimination. Target discrimination is usually formulated as an inverse problem typically requiring fast forward models for efficiency. The most successful and widely applied EMI forward model is the simple dipole model, which works well for simple objects when the observation points are not close to the target. For complicated cases, a single dipole is not sufficient and a number of dipoles (displaced dipoles) has been suggested. However, once more than one dipole is needed, it is difficult to infer a unique set of model parameters from measurement data, which is usually limited. Inspired by the displaced dipole model, we developed the dumbbell dipole model, which consists of a special combination of dipoles. We placed a center dipole and two anti-symmetric side dipoles on the target axis. The center dipole functions like the traditional single dipole model and the two side dipoles provide the non-symmetric response of the target. When the distance between dipoles is small, this model is essentially a dipole plus a quadrupole. The advantage of the dumbbell model is that the model parameters can be inferred more easily from measurement data. The center dipole represents the main response of the target, the side dipoles act as additional backup in case a simple dipole is not sufficient. Regularization terms are applied so that the dumbbell dipole model automatically reduces to the simple dipole model in degenerate cases. Preliminary test shows that the dumbbell model can fit the measurement data better than the simple dipole model, and the inferred model parameters are unique for a given UXO. This suggests that the model parameters can be used as a discriminator for UXO. In this paper the dumbbell dipole model is introduced and its performance is compared with that of both the simple dipole model and the displaced dipole model.
Abdallah, Zeina; Boucher, Yann G.; Fernandez, Arnaud; Balac, Stéphane; Llopis, Olivier
2016-01-01
A microwave domain characterization approach is proposed to determine the properties of high quality factor optical resonators. This approach features a very high precision in frequency and aims to acquire a full knowledge of the complex transfer function (amplitude and phase) characterizing an optical resonator using a microwave vector network analyzer. It is able to discriminate between the different coupling regimes, from the under-coupling to the selective amplification, and it is used together with a model from which the main resonator parameters are extracted, i.e. coupling factor, intrinsic losses, phase slope, intrinsic and external quality factor. PMID:27251460
Observation of Stueckelberg oscillations in dipole-dipole interactions
Ditzhuijzen, C. S. E. van; Tauschinsky, Atreju; Van Linden van den Heuvell, H. B.
2009-12-15
We have observed Stueckelberg oscillations in the dipole-dipole interaction between Rydberg atoms with an externally applied radio-frequency field. The oscillating rf field brings the interaction between cold Rydberg atoms in two separated volumes into resonance. We observe multiphoton transitions when varying the amplitude of the rf field and the static electric field offset. The angular momentum states we use show a quadratic Stark shift, which leads to a fundamentally different behavior than linearly shifting states. Both cases are studied theoretically using the Floquet approach and are compared. The amplitude of the sidebands, related to the interaction strength, is given by the Bessel function in the linearly shifting case and by the generalized Bessel function in the quadratically shifting case. The oscillatory behavior of both functions corresponds to Stueckelberg oscillations, an interference effect described by the semiclassical Landau-Zener-Stueckelberg model. The measurements prove coherent dipole-dipole interaction during at least 0.6 mus.
Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure
Zlobin, Alexander; Andreev, Nicolai; Barzi, Emanuela; Chlachidze, Guram; Kashikhin, Vadim; Nobrega, Alfred; Novitski, Igor; Turrioni, Daniele; Karppinen, Mikko; Smekens, David
2014-07-01
FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC. To optimize coil design parameters and fabrication process and study coil performance, a series of 1 m long dipole coils is being fabricated. One of the short coils has been tested using a dipole mirror structure. This paper describes the dipole mirror magnetic and mechanical designs, and reports coil parameters and test results.
Schillebeeckx, P.; Becker, B.; Danon, Y.; Guber, K.; Harada, H.; Heyse, J.; Junghans, A.R.; Kopecky, S.; Massimi, C.; Moxon, M.C.; Otuka, N.; Sirakov, I.; Volev, K.
2012-12-15
Cross section data in the resolved and unresolved resonance region are represented by nuclear reaction formalisms using parameters which are determined by fitting them to experimental data. Therefore, the quality of evaluated cross sections in the resonance region strongly depends on the experimental data used in the adjustment process and an assessment of the experimental covariance data is of primary importance in determining the accuracy of evaluated cross section data. In this contribution, uncertainty components of experimental observables resulting from total and reaction cross section experiments are quantified by identifying the metrological parameters involved in the measurement, data reduction and analysis process. In addition, different methods that can be applied to propagate the covariance of the experimental observables (i.e. transmission and reaction yields) to the covariance of the resonance parameters are discussed and compared. The methods being discussed are: conventional uncertainty propagation, Monte Carlo sampling and marginalization. It is demonstrated that the final covariance matrix of the resonance parameters not only strongly depends on the type of experimental observables used in the adjustment process, the experimental conditions and the characteristics of the resonance structure, but also on the method that is used to propagate the covariances. Finally, a special data reduction concept and format is presented, which offers the possibility to store the full covariance information of experimental data in the EXFOR library and provides the information required to perform a full covariance evaluation.
New evaluation of the{sup 232}Th resonance parameters in the energy range
Derrien, H.; Leal, L. C.; Larson, N. M.
2006-07-01
Neutron resonance parameters of {sup 232}Th were obtained from a Reich-Moore SAMMY analysis of high-resolution neutron transmission measurements performed at the Oak Ridge Linear Accelerator (ORELA) by Olsen et al. in 1981 and of high-resolution neutron capture measurements performed recently at the Geel Linear Accelerator (GELINA (Belgium)) by Schillebeeckx et al. and at n-TOF (CERN (Switzerland)) by Aerts et al. The ORELA data were analyzed previously by Olsen using the Breit-Wigner multilevel code SIOB, and their results were used for the ENDF/B-VI evaluation. In our new analysis of the Olsen neutron transmissions using the modern computer code SAMMY, better accuracy is obtained for the resonance parameters by including recent experimental neutron capture data in the experimental data base. The experimental data base and the method of analysis are described in the report. Neutron transmissions and capture cross sections calculated with the resonance parameters are compared to the experimental values. A description is given of the statistical properties of the resonance parameters. The new evaluation produces a decrease in the capture resonance integral, and improves the prediction of integral thermal benchmarks. (authors)
Analysis of the loop-coupled log-periodic dipole array
NASA Astrophysics Data System (ADS)
Tranquilla, J. M.; Balmain, K. G.
1983-03-01
A simple theoretical model is described to analyze the loop-coupled log-periodic dipole antenna (LPDA). Computed and experimental data are presented, comprising an investigation into both the far field and the dipole and feeder currents, for a wide range of antenna parameters. Particular attention is paid to a class of parasitic resonances characterized in the swept-frequency radiation pattern by a narrow-band reduction in front-to-back ratio. The calculations show that these resonances involve high out-of-phase currents in adjacent dipole elements, and also predict correctly their dependence on the nature and location of the feedline termination. Design data are presented showing how gain and front-to-back ratio can be optimized and parasitic resonance effects minimized.
Mughabghab, S.F.; Divadeenam, M.
1981-01-01
The resonance parameters and thermal cross sections of /sup 235/ /sup 238/U and /sup 239/ /sup 240/ /sup 241/ /sup 242/Pu are reevaluated by considering the measurements carried out since 1973. Capture, scattering, fission cross sections as well as resonance integrals are calculated from the parameters and are compared with experimental values with the objective of achieving consistency between calculations and measurements. The Dyson-Metha ..delta../sub 3/ statistical analysis was applied in order to calculate average level spacings. Calculations of average radiative widths based on systematics are carried out and are compared with experimental values as well as with Moore's and Lynn's estimates.
RHIC VERTICAL AC DIPOLE COMMISSIONING.
BAI,M.; DELONG,J.; HOFF,L.; PAI,C.; PEGGS,S.; PIACENTINO,J.; OERTER,B.; ODDO,P.; ROSER,T.; SATOGATA,T.; TRBOJEVIC,D.; ZALTSMAN,A.
2002-06-02
The RHIC vertical ac dipole was installed in the summer of 2001. The magnet is located in the interaction region between sector 3 and sector 4 common to both beams. The resonant frequency of the ac dipole was first configured to be around half of the beam revolution frequency to act as a spin flipper. At the end of the RHIC 2002 run, the ac dipole frequency was reconfigured for linear optics studies. A 0.35 mm driven betatron oscillation was excited with the vertical ac dipole and the vertical betatron functions and phase advances at each beam position monitor (BPM) around the RHIC yellow ring were measured using the excited coherence. We also recorded horizontal turn-by-turn beam positions at each BPM location to investigate coupling effects. Analysis algorithms and measurement results are presented.
NASA Technical Reports Server (NTRS)
Bailey, M. C.
1985-01-01
A 6X6 array of fan-dipoles was designed to operate in the 510 to 660 MHz frequency range for aircraft flight test and evaluation of a UHF radiometer system. A broad-band dipole design operating near the first resonance is detailed. Measured VSWR and radiation patterns for the dipole array demonstrate achievable bandwidths in the 35 percent to 40 percent range.
Wang, Ji; Zhao, Wenhua; Du, Jianke
2006-12-22
Recently, as the dissipation of quartz crystal through material viscosity is being considered in vibrations of piezoelectric plates, we have the opportunity to obtain electrical parameters from vibration solutions of a crystal plate representing an ideal resonator. Since the solutions are readily available with complex elastic constants from Mindlin plate equations for thickness-shear vibrations, the calculation of resistance and other parameters related to both mechanical deformation and electrical potential is straightforward. We start with the first-order Mindlin plate equations of a piezoelectric plate for the thickness-shear vibration analysis of a simple resonator model. The electrical parameters are derived with emphasis on the resistance that is related to the imaginary part of complex elastic constants, or the viscosity. All the electrical parameters are frequency dependent, enabling the study of the frequency behavior of crystal resonators with a direct formulation. Through the full consideration of complications like partial electrodes and supporting structures, we should be able obtain electrical parameters for practical applications in resonator design.
Comparison of Resonance Parameter Covariance Generation using CONRAD and SAMMY Computer Codes
Leal, Luiz C; De Saint Jean, C; Noguere, G
2010-01-01
Cross section evaluations in the resolved resonance region are based on formalisms derived from the R-matrix theory. As a result, the evaluations provide a set of resonance parameters that can be used to reproduce the experimental data reasonably well. The evaluated nuclear data are used in neutron transport calculations for the analysis and design of nuclear reactor systems, nuclear criticality safety analyses, etc. To achieve the desired accuracy on the nuclear system calculations, the questions frequently asked are how well the nuclear data are known and how the uncertainty in the nuclear data can be propagated into the final nuclear system results. There have been ongoing efforts at several research centers for generating data uncertainties in the resonance and high-energy regions. The biggest issue in relation to the covariance data is how good the calculated uncertainties are or whether the calculated uncertainties are in agreement with realistic uncertainties derived from an experimental nuclear system or nuclear benchmark. In this work an attempt is made to use two distinct and independently developed computer codes, CONRAD and SAMMY, to evaluate and generate covariance data in the resonance region. The verification study has been performed in support of the U.S. Nuclear Criticality Safety program (NCSP) as the NCSP is working to provide improved nuclear data files to support criticality safety analyses. The objective is to check the procedures and the methodologies used in the resonance region for covariance generation. The studies have been carried out using the 48Ti resolved resonance parameters.
Patil, N R; Melavanki, R M; Kapatkar, S B; Ayachit, N H; Saravanan, J
2011-05-01
The absorption and fluorescence spectra of three Carboxamides namely (E)-2-(4-Chlorobenzylideneamino)-N-(2-chlorophenyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(1)), (E)-N-(3-Chlorophenyl)-2-(3, 4-dimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(2)) and (E)-N-(3-Chlorophenyl)-2-(3,4,5-trimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide (C(3)) have been recorded at room temperature in solvents of different polarities using dielectric constant (ε) and refractive index (n). Experimental ground (μ(g)) and excited (μ(e)) state dipole moments are estimated by means of solvatochromic shift method and also the excited dipole moments are estimated in combination with ground state dipole moments. It was estimated that dipole moments of the excited state were higher than those of the ground state of all three molecules. Further, the changes in dipole moment (Δμ) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter (E(N)(T)) and the values are compared.
NASA Astrophysics Data System (ADS)
Sahoo, B. K.
2017-01-01
Combining the recently reported electric dipole moment (EDM) of the 199Hg atom due to breaking of parity and time-reversal symmetries with the improved relativistic atomic calculations, precise limits on the tensor-pseudotensor (T-PT) electron-nucleus (e-N) coupling coefficient and the nuclear Schiff moment interactions are determined. Using these limits with the nuclear calculations, we infer limits on the EDMs of the neutron and proton as dn<2.2 ×10-26 |e |cm and dp<2.1 ×10-25 |e |cm , respectively, and on the quantum chromodynamics parameter and the combined up- and down-quark chromo-EDMs as |θ ¯|<1.1 ×10-10 and |d˜ u-d˜ d|<5.5 ×10-27 |e |cm , respectively. These are the best limits to date to probe new sources of C P violation beyond the standard model from a diamagnetic atom. The role of a capable many-body method to account for the electron correlation effects to all orders for inferring the above limits has been highlighted. From this analysis, constraints on the T-PT e-N coupling coefficient with a large range of mass of a possible dark matter carrier χ between the atomic electrons and nucleus are given.
Dipole-dipole dispersion interactions between neutrons
NASA Astrophysics Data System (ADS)
Babb, James F.; Higa, Renato; Hussein, Mahir S.
2017-06-01
We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the Δ-resonance (J^{π} = +3/2, I = 3/2). We found both dynamical effects to be quite relevant for distances r between ˜ 50 fm up to ˜ 103 fm in the nn system, the neutron-wall system and in the wall-neutron-wall system, reaching the expected asymptotic limit beyond that. Relevance of our findings to the confinement of ultra cold neutrons inside bottles is discussed.
Very Broad X(4260) and the Resonance Parameters of the ψ(3D) Vector Charmonium State
NASA Astrophysics Data System (ADS)
van Beveren, Eef; Rupp, George; Segovia, J.
2010-09-01
We argue that the X(4260) enhancement contains a wealth of information on 1-- cc¯ spectroscopy. We discuss the shape of the X(4260) observed in the Okubo-Zweig-Iizuka-forbidden process e+e-→π+π-J/ψ, in particular, at and near vector charmonium resonances as well as open-charm threshold enhancements. The resulting very broad X(4260) structure does not seem to classify itself as a 1-- cc¯ resonance, but its detailed shape allows us to identify new vector charmonium states with higher statistics than in open-charm decay. Here, we estimate the resonance parameters of the ψ(3D). Our approach also provides an explanation for the odd dip in the π+π-J/ψ data precisely at the ψ(4415) resonance.
Very Broad X(4260) and the Resonance Parameters of the {psi}(3D) Vector Charmonium State
Beveren, Eef van; Rupp, George; Segovia, J.
2010-09-03
We argue that the X(4260) enhancement contains a wealth of information on 1{sup --} cc spectroscopy. We discuss the shape of the X(4260) observed in the Okubo-Zweig-Iizuka-forbidden process e{sup +}e{sup -}{yields}{pi}{sup +}{pi}{sup -}J/{psi}, in particular, at and near vector charmonium resonances as well as open-charm threshold enhancements. The resulting very broad X(4260) structure does not seem to classify itself as a 1{sup --} cc resonance, but its detailed shape allows us to identify new vector charmonium states with higher statistics than in open-charm decay. Here, we estimate the resonance parameters of the {psi}(3D). Our approach also provides an explanation for the odd dip in the {pi}{sup +}{pi}{sup -}J/{psi} data precisely at the {psi}(4415) resonance.
Dipole-dipole interaction in electronic article surveillance system
NASA Astrophysics Data System (ADS)
Pan, H. L.; Li, X.; Zhang, Q.; Wang, J. T.; Xie, W. H.; Zhao, Z. J.
2017-08-01
The dipole-dipole interaction in electronic article surveillance system is studied in this paper. The acoustic magnetic properties investigations were performed on amorphous ribbon Fe24Co11.82Ni47.3Si1.47B15 with a size of 38.5 mm × 6 mm × 0.03 mm at room temperature. The results showed that the dependence of resonance amplitude and frequency on the external magnetic field varied with the number of ribbons. To understand the mechanism, hysteresis loops in arrays of N ribbons with and without a bias magnet have been performed. A theoretical model was used to calculate the dipolar fields among the ribbons and the magnet. The ribbons without a bias magnet exhibited a higher anisotropy field as the number of ribbons increased, which arises from the dipole-dipole interaction between them. The plateau and kink in hysteresis loops with bias magnets also change with the number of ribbons because of the dipole-dipole interactions among the ribbons themselves, and the interaction between the ribbons and the bias magnet also. The superimposed dipolar field affects the acoustic magnetic properties of the ribbons in electronic article surveillance system.
On the Methodology to Calculate the Covariance of Estimated Resonance Parameters
Becker, B.; Kopecky, S.; Schillebeeckx, P.
2015-01-15
Principles to determine resonance parameters and their covariance from experimental data are discussed. Different methods to propagate the covariance of experimental parameters are compared. A full Bayesian statistical analysis reveals that the level to which the initial uncertainty of the experimental parameters propagates, strongly depends on the experimental conditions. For high precision data the initial uncertainties of experimental parameters, like a normalization factor, has almost no impact on the covariance of the parameters in case of thick sample measurements and conventional uncertainty propagation or full Bayesian analysis. The covariances derived from a full Bayesian analysis and least-squares fit are derived under the condition that the model describing the experimental observables is perfect. When the quality of the model can not be verified a more conservative method based on a renormalization of the covariance matrix is recommended to propagate fully the uncertainty of experimental systematic effects. Finally, neutron resonance transmission analysis is proposed as an accurate method to validate evaluated data libraries in the resolved resonance region.
NASA Astrophysics Data System (ADS)
Diao, Wenting; He, Jun; Liu, Bei; Wang, Junmin
2012-11-01
This work deals with the cooling and trapping of single cesium (Cs) atoms in a large-magnetic-gradient magneto-optical trap (MOT) and the confinement of single Cs atoms in a far-off-resonance optical dipole trap (FORT). The experiment setup is based on two large-numerical-aperture lens assemblies which allow us to strongly focus a 1064-nm TEM00-mode Gaussian laser beam to a 1/e2 radius of ~ 2.3 μm to form a microscopic FORT for isolating single atom with environment and to efficiently collect the laser-induced-fluorescence photons emitted by single atoms for detecting and recognizing single atom's internal state. We have tried both of "bottom-up" and "top-down" loading schemes to confine single atoms in the microscopic FORT. In the "bottom-up" scheme, we have successfully prepared single Cs atoms in the MOT and transferred it into FORT with a probability of almost 100%. In the "top-down" scheme, we have achieved ~ 74% of single atom loading probability in the FORT using light-assisted collisions induced by blue detuning laser and with prepared many Cs atoms in the MOT. The relaxation time in hyperfine level of ground state of trapped single Cs atom is measured to be ~5.4 s. To coherently manipulate atomic quantum bits (qubit) encoded in the clock states (mF = 0 states in Fg = 3 and 4 hyperfine levels) of single Cs atom via the two-photon simulated Raman adiabatic passage (STIRAP), we have prepared two phase-locked laser beams with a frequency difference of ~ 9.192 GHz by optically injecting an 852-nm master laser to lock the +1-order sideband of a 9-GHz current-modulated slave diode laser. The two phase-locked laser beams are used to drive STIRAP process in the Λ-type three-level system consists of Cs |6S1/2 Fg = 4, mF = 0> and |6S1/2 Fg = 3, mF = 0< long-lived clock states and Cs |6S1/2 Fe = 4, mF = +1 > excited state with the single-photon detuning of ~ -20 GHz. Rabi flopping experiments are in progress.
NONLINEAR DIAGNOSTICS USING AC DIPOLES.
PEGGS,S.
1999-03-29
There are three goals in the accurate nonlinear diagnosis of a storage ring. First, the beam must be moved to amplitudes many times the natural beam size. Second, strong and long lasting signals must be generated. Third, the measurement technique should be non-destructive. Conventionally, a single turn kick moves the beam to large amplitudes, and turn-by-turn data are recorded from multiple beam position monitors (BPMs) [1-6]. Unfortunately, tune spread across the beam causes the center of charge beam signal to ''decohere'' on a time scale often less than 100 turns. Filamentation also permanently destroys the beam emittance (in a hadron ring). Thus, the ''strong single turn kick'' technique successfully achieves only one out of the three goals. AC dipole techniques can achieve all three. Adiabatically excited AC dipoles slowly move the beam out to large amplitudes. The coherent signals then recorded last arbitrarily long. The beam maintains its original emittance if the AC dipoles are also turned off adiabatically, ready for further use. The AGS already uses an RF dipole to accelerate polarized proton beams through depolarizing resonances with minimal polarization loss [7]. Similar AC dipoles will be installed in the horizontal and vertical planes of both rings in RHIC [8]. The RHIC AC dipoles will also be used as spin flippers, and to measure linear optical functions [9].
Evaluation of Silicon Neutron Resonance Parameters in the Energy Range Thermal to 1800 keV
Derrien, H.
2002-09-30
The evaluation of the neutron cross sections of the three stable isotopes of silicon in the energy range thermal to 20 MeV was performed by Hetrick et al. for ENDF/B-VI (Evaluated Nuclear Data File). Resonance parameters were obtained in the energy range thermal to 1500 keV from a SAMMY analysis of the Oak Ridge National Laboratory experimental neutron transmission data. A new measurement of the capture cross section of natural silicon in the energy range 1 to 700 keV has recently been performed at the Oak Ridge Electron Linear Accelerator. Results of this measurement were used in a SAMMY reevaluation of the resonance parameters, allowing determination of the capture width of a large number of resonances. The experimental data base is described; properties of the resonance parameters are given. For the first time the direct neutron capture component has been taken into account from the calculation by Rauscher et al. in the energy range from thermal to 1 MeV. Results of benchmark calculations are also given. The new evaluation is available in the ENDF/B-VI format.
Tweten, D J; Okamoto, R J; Bayly, P V
2017-01-17
To establish the essential requirements for characterization of a transversely isotropic material by magnetic resonance elastography (MRE). Three methods for characterizing nearly incompressible, transversely isotropic (ITI) materials were used to analyze data from closed-form expressions for traveling waves, finite-element (FE) simulations of waves in homogeneous ITI material, and FE simulations of waves in heterogeneous material. Key properties are the complex shear modulus μ2 , shear anisotropy ϕ=μ1/μ2-1, and tensile anisotropy ζ=E1/E2-1. Each method provided good estimates of ITI parameters when both slow and fast shear waves with multiple propagation directions were present. No method gave accurate estimates when the displacement field contained only slow shear waves, only fast shear waves, or waves with only a single propagation direction. Methods based on directional filtering are robust to noise and include explicit checks of propagation and polarization. Curl-based methods led to more accurate estimates in low noise conditions. Parameter estimation in heterogeneous materials is challenging for all methods. Multiple shear waves, both slow and fast, with different propagation directions, must be present in the displacement field for accurate parameter estimates in ITI materials. Experimental design and data analysis can ensure that these requirements are met. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Cluggish, B.; Zhao, L.; Kim, J. S.
2010-02-15
Although heating power and gas pressure are two of the two of primary experimental ''knobs'' available to users of electron cyclotron resonance ion sources, there is still no clear understanding of how they interact in order to provide optimal plasma conditions. FAR-TECH, Inc. has performed a series of simulations with its generalized electron cyclotron resonance ion source model in which the power and pressure were varied over a wide range. Analysis of the numerical data produces scaling laws that predict the plasma parameters as a function of the power and pressure. These scaling laws are in general agreement with experimental data.
NASA Astrophysics Data System (ADS)
Kanno, Ryutaro; Nunami, Masanori; Satake, Shinsuke; Takamaru, Hisanori; Okamoto, Masao
2013-06-01
We investigate how the neoclassical thermal diffusivity of an axisymmetric toroidal plasma is modified by the effect of resonant magnetic perturbations (RMPs), using a drift-kinetic simulation code for calculating the radial thermal diffusivity of ion in the perturbed region under an assumption of zero electric field. Here, the perturbed region is assumed to be generated on and near the resonance surfaces, and is wedged in between the regular closed magnetic surfaces. We find that the dependence of the radial thermal diffusivity on parameters of the toroidal plasma is represented as \\chi_r=\\chi_r^{(0)} \\{1+ c_0\\,(\\omega_b/\
Stochastic Parameter Resonance of Road-Vehicle Systems and Related Bifurcation Problems
NASA Astrophysics Data System (ADS)
Wedig, Walter V.
The paper investigates stochastic dynamics of road-vehicle systems and related bifurcation problems. The ride on rough roads generates vertical car vibrations whose root-mean-squares are resonant for critical car speeds and vanish when the car velocity is increasing, infinitely. These investigations are extended to wheel suspensions with progressive spring characteristics. For weak but still positive damping, the car vibrations become unstable when the velocity reaches the parameter resonance near twice the critical speed bifurcating into stochastic chaos of larger non-stationary car vibrations.
NASA Astrophysics Data System (ADS)
Páez, Rocío Isabel; Efthymiopoulos, Christos
2015-02-01
The possibility that giant extrasolar planets could have small Trojan co-orbital companions has been examined in the literature from both viewpoints of the origin and dynamical stability of such a configuration. Here we aim to investigate the dynamics of hypothetical small Trojan exoplanets in domains of secondary resonances embedded within the tadpole domain of motion. To this end, we consider the limit of a massless Trojan companion of a giant planet. Without other planets, this is a case of the elliptic restricted three body problem (ERTBP). The presence of additional planets (hereafter referred to as the restricted multi-planet problem, RMPP) induces new direct and indirect secular effects on the dynamics of the Trojan body. The paper contains a theoretical and a numerical part. In the theoretical part, we develop a Hamiltonian formalism in action-angle variables, which allows us to treat in a unified way resonant dynamics and secular effects on the Trojan body in both the ERTBP or the RMPP. In both cases, our formalism leads to a decomposition of the Hamiltonian in two parts, . , called the basic model, describes resonant dynamics in the short-period (epicyclic) and synodic (libration) degrees of freedom, while contains only terms depending trigonometrically on slow (secular) angles. is formally identical in the ERTBP and the RMPP, apart from a re-definition of some angular variables. An important physical consequence of this analysis is that the slow chaotic diffusion along resonances proceeds in both the ERTBP and the RMPP by a qualitatively similar dynamical mechanism. We found that this is best approximated by the paradigm of `modulational diffusion'. In the paper's numerical part, we then focus on the ERTBP in order to make a detailed numerical demonstration of the chaotic diffusion process along resonances. Using color stability maps, we first provide a survey of the resonant web for characteristic mass parameter values of the primary, in which the
Kiełczyński, Piotr; Szalewski, Marek
2007-06-01
The electro-elastic behavior of a viscoelastically loaded layered cylindrical resonator (sensor) comprising two coupled hollow cylinders is presented. The inner cylinder is a piezoelectric ceramic tube. The outer cylinder is a non-piezoelectric (passive) metallic cylinder. An analytical formula for the electrical admittance of a compound layered cylindrical resonator loaded with a viscoelastic liquid is established. Admittance (conductance) diagrams were obtained using a continuum electromechanical model. The established analytical formulas enable the determination of the influence of the liquid viscosity, material, and geometrical parameters of a compound cylindrical resonator on the response characteristics of the compound sensor. In the paper, the sensor implications resulting from the performed analysis are described. Moreover, the algorithm of the method developed by the authors to evaluate the rheological parameters of a viscoelastic liquid is presented. Good agreement between the theoretical results and experimental data is shown. The analysis presented in this paper can be utilized for the design and construction of cylindrical piezoelectric viscosity sensors, annular accelerometers, filters, transducers, and multilayer resonators.
Zhang, Jinjing; Zhang, Tao
2015-02-15
The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N{sup 2}) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm.
Dynamic dipole polarizability of Li{sup +} embedded in plasmas
Kar, S.; Kamali, M. Z. M.; Ratnavelu, K.
2014-03-05
Dynamic dipole polarizabilities of the system Li{sup +} embedded in weakly coupled plasmas are investigated using highly correlated exponential wave functions in the framework of the pseudostate summation technique. The Debye-Hückel shielding approach of plasma modeling is used to represent weakly coupled plasma environment. In free-atomic cases, results obtained from the present study are in agreement with the available calculations. Frequency-dependent polarizability of Li{sup +} as function of screening parameter is presented for the first time. Resonance frequencies for Li{sup +} are also presented in terms of screening parameter.
Probing weak dipole-dipole interaction using phase-modulated nonlinear spectroscopy
NASA Astrophysics Data System (ADS)
Li, Zeng-Zhao; Bruder, Lukas; Stienkemeier, Frank; Eisfeld, Alexander
2017-05-01
Phase-modulated nonlinear spectroscopy with higher harmonic demodulation has recently been suggested to provide information on many-body excitations. In the present work we theoretically investigate the application of this method to infer the interaction strength between two particles that interact via weak dipole-dipole interaction. To this end we use a full numerical solution of the Schrödinger equation with time-dependent pulses. For interpretation purposes we also derive analytical expressions in perturbation theory. We find one can detect dipole-dipole interaction via peak intensities (in contrast to line-shifts which typically are used in conventional spectroscopy). We provide a detailed study on the dependence of these intensities on the parameters of the laser pulse and the dipole-dipole interaction strength. Interestingly, we find that there is a phase between the first and second harmonic demodulated signal whose value depends on the sign of the dipole-dipole interaction.
Nakayama, S.; Matsumoto, E.; Fushimi, K.; Hayami, R.; Kawasuso, H.; Yasuda, K.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Asaji, S.; Ishida, T.; Kudoh, T.; Sagara, K.; Fujiwara, M.; Hashimoto, H.; Kawase, K.; Nakanishi, K.; Oota, T.; Yosoi, M.; Greenfield, M. B.
2008-07-15
We studied analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) in {sup 4}He and in the {alpha} clusters of {sup 6,7}Li via the ({sup 7}Li,{sup 7}Be{gamma}) reactions on {sup 4}He, {sup 6}Li, and {sup 7}Li at an incident energy of 455 MeV and at a scattering angle of 0 deg. by measuring spin-nonflip and spin-flip spectra. The reaction Q-values for the analogs of the GDR and SDR in the {alpha} clusters of {sup 6,7}Li were found to be more negative than those in {sup 4}He by 2.0{+-}0.5 MeV. The ratios of the cross section for the analog of the GDR to that for the analog of the SDR in {sup 4}He and in the {alpha} clusters of {sup 6}Li and {sup 7}Li were found to be the same within errors, 0.5{+-}0.1. The cross sections for the analogs of the GDR as well as those for the analogs of the SDR in the {alpha} clusters of {sup 6,7}Li were 0.6{approx}0.8 times smaller than those in {sup 4}He. These results suggest that excitations of {alpha} clusters embedded in nuclei are suppressed as compared with excitations of free {alpha} particles.
On Dipole Moment of Impurity Carbon Nanotubes
NASA Astrophysics Data System (ADS)
Konobeeva, N. N.; Ten, A. V.; Belonenko, M. B.
2017-04-01
Propagation of a two-dimensional electromagnetic pulse in an array of semiconductor carbon nanotubes with impurities is investigated. The parameters of dipole moments of impurities are determined. The Maxwell equation and the equation of motion for dipole polarization are jointly solved. The dynamics of the electromagnetic pulse is examined as a function of the dipole moment. It is shown that taking polarization into account does not have a substantial effect on the propagation process, but alters the optical pulse shape.
Amin, Naima; Afzal, Mohammad
2009-04-01
To evaluate the practical impact of alteration of key imaging parameters of Magnetic Resonance Imaging on image quality and effectiveness provided by widely available fast imaging pulse sequences. A tissue equivalent material for Magnetic resonance Imaging (MRI) has been produced from a polysaccharide gel, agros, containing gadolinium chloride chelated to Ethylene Diamine Tetra- Acetic acid (EDTA) with a sort of T1 and T2 values. Experimental variations in key parameters included echo time (TE) and repetition time TR. Quantitative analysis consisted of image nonuniformity. In T2 weighted images; any change in TE played a critical role in the signal homogeneity in all pulse sequences. The percentage of nonuniformity was incredibly high in T2 weighted image but the change of TR was insignificant in T2-weighted study. Involving T1 weighted images, percentage of nonuniformity was high in gradient recalled echo (GRE), also noticeable in fast fluid attenuated recovery (FLAIR) but quite acceptable in fast spin echo (FSE) and conventional spin echo (CSE). Selection of parameters relatively simple in CSE both in T1, T2-weighted study that maintains image uniformity and quality as well. GRE is a very sensitive pulse sequence for any variation in parameters and loose signal uniformity rapidly.
Evaluation of silicon neutron resonance parameters in the thermal to 1800 keV energy range.
Derrien, H; Leal, L C; Guber, K H; Larson, N M
2005-01-01
Because silicon is a major constituent of concrete and soil, neutron and gamma ray information on silicon is important for reactor shielding and criticality safety calculations. Therefore, much effort was put into the ENDF/B-VI evaluation for the three stable isotopes of silicon. The neutron capture cross section of natural silicon was recently measured at the Oak Ridge Electron Linear Accelerator (ORELA) in the energy range 1-700 keV. Using the ENDF/B-VI evaluation for initial values, a new evaluation of the resonance parameters was performed by adding the results of the ORELA capture measurements to the experimental database. The computer code SAMMY was used for the analysis of the experimental data; the new version of SAMMY allows accurate calculations of the self-shielding and multiple scattering effects in the capture measurements. The accuracy of the radiative capture widths of the resonances was improved by this analysis. Accurate values of the s-, p- and d-wave neutron strength functions were also obtained. Although the resonance capture component of the present evaluation is 2-3 times smaller than that in ENDF/B-VI, the total capture cross section is much larger, at least for energies >250 keV, because the direct capture component contributes values of the same order of magnitude as the resonance component. The direct component was not taken into account in the ENDF/B-VI evaluation and was calculated for the first time in the present evaluation.
A parameter study of mode conversion at ion-ion hybrid resonances for ICRF-heating
NASA Astrophysics Data System (ADS)
Alava, M. J.; Heikkinen, J. A.
1992-04-01
By solving the wave equation for the radial electric field with constant poloidal electric field around the resonance layer of the fast Alfvén wave, various complex characteristics of mode conversion physics can be elucidated and analyzed for ion cyclotron heating of tokamaks. The validity of the Budden and tunnelling model [Ngan, Y. C. and Swanson, D. G., Phys. Fluids 20, 1920 (1977)] for the conversion studies is explored, and the conversion coefficient for the ion-ion hybrid resonance in the presence of cyclotron damping is found in closed form. The analytical results are compared with the numerical solution of the full wave equations expanded to second order in ion Larmor radius. It is found that the standard tunnelling solutions can be erroneous, not only in the case of strong damping, but also when the linearization of the plasma parameters around the resonance, peculiar to the tunnelling model, becomes inaccurate. The effects of the damping and cavity resonances on the conversion are separated in the derived analytical estimates, and the limits of the local theory of conversion are determined.
Large scale integration of CVD-graphene based NEMS with narrow distribution of resonance parameters
NASA Astrophysics Data System (ADS)
Arjmandi-Tash, Hadi; Allain, Adrien; (Vitto Han, Zheng; Bouchiat, Vincent
2017-06-01
We present a novel method for the fabrication of the arrays of suspended micron-sized membranes, based on monolayer pulsed-CVD graphene. Such devices are the source of an efficient integration of graphene nano-electro-mechanical resonators, compatible with production at the wafer scale using standard photolithography and processing tools. As the graphene surface is continuously protected by the same polymer layer during the whole process, suspended graphene membranes are clean and free of imperfections such as deposits, wrinkles and tears. Batch fabrication of 100 μm-long multi-connected suspended ribbons is presented. At room temperature, mechanical resonance of electrostatically-actuated devices show narrow distribution of their characteristic parameters with high quality factor and low effective mass and resonance frequencies, as expected for low stress and adsorbate-free membranes. Upon cooling, a sharp increase of both resonant frequency and quality factor is observed, enabling to extract the thermal expansion coefficient of CVD graphene. Comparison with state-of-the-art graphene NEMS is presented.
NASA Astrophysics Data System (ADS)
Wang, Lei; Nie, Jinsong; Wang, Xi; Hu, Yuze
2016-10-01
The 1064nm fundamental wave (FW) and the 532nm second harmonic wave (SHW) of Nd:YAG laser have been widely applied in many fields. In some military applications requiring interference in both visible and near-infrared spectrum range, the de-identification interference technology based on the dual wavelength composite output of FW and SHW offers an effective way of making the device or equipment miniaturized and low cost. In this paper, the application of 1064nm and 532nm dual-wavelength composite output technology in military electro-optical countermeasure is studied. A certain resonator configuration that can achieve composite laser output with high power, high beam quality and high repetition rate is proposed. Considering the thermal lens effect, the stability of this certain resonator is analyzed based on the theory of cavity transfer matrix. It shows that with the increase of thermal effect, the intracavity fundamental mode volume decreased, resulting the peak fluctuation of cavity stability parameter. To explore the impact the resonator parameters does to characteristics and output ratio of composite laser, the solid-state laser's dual-wavelength composite output models in both continuous and pulsed condition are established by theory of steady state equation and rate equation. Throughout theoretical simulation and analysis, the optimal KTP length and best FW transmissivity are obtained. The experiment is then carried out to verify the correctness of theoretical calculation result.
Bobbili, Prasada Rao; Nayak, Jagannath; Pinnoji, Prerana Dabral; Rama Koti Reddy, D V
2016-03-10
The accuracy of the resonant frequency servo loop is a major concern for the high-performance operation of a resonant fiber optic gyro. For instance, a bias error as large as tens or even hundreds of degrees/hour has been observed at the demodulated output of the resonant frequency servo loop. The traditional frequency servo mechanism is not an efficient tool to address this problem. In our previous work, we proposed a novel method to minimize the laser frequency noise to the level of the shot noise by refractive index modulation by a thermally tunable resonator. In this paper, we performed the parameter optimization for the resonator coil, multifunction integrated-optics chip, and couplers by the transition matrix using the Jones matrix methodology to minimize the polarization error. With the optimized parameter values, we achieved the bias value of the resonator fiber optic gyro to 1.924°/h.
NASA Astrophysics Data System (ADS)
Liu, Jian; Wang, You-Guo; Zhai, Qi-Qing; Liu, Jin
2016-10-01
In this paper, we propose a parameter allocation scheme in a parallel array bistable stochastic resonance-based communication system (P-BSR-CS) to improve the performance of weak binary pulse amplitude modulated (BPAM) signal transmissions. The optimal parameter allocation policy of the P-BSR-CS is provided to minimize the bit error rate (BER) and maximize the channel capacity (CC) under the adiabatic approximation condition. On this basis, we further derive the best parameter selection theorem in realistic communication scenarios via variable transformation. Specifically, the P-BSR structure design not only brings the robustness of parameter selection optimization, where the optimal parameter pair is not fixed but variable in quite a wide range, but also produces outstanding system performance. Theoretical analysis and simulation results indicate that in the P-BSR-CS the proposed parameter allocation scheme yields considerable performance improvement, particularly in very low signal-to-noise ratio (SNR) environments. Project supported by the National Natural Science Foundation of China (Grant No. 61179027), the Qinglan Project of Jiangsu Province of China (Grant No. QL06212006), and the University Postgraduate Research and Innovation Project of Jiangsu Province (Grant Nos. KYLX15_0829, KYLX15_0831).
Chakrapani, Sunil Kishore; Barnard, Daniel J
2017-02-01
The present article investigates the possibility of using nonlinear resonance ultrasound spectroscopy to determine the acoustic nonlinearity parameter (β) and third order elastic constant by developing an inverse problem. A theoretical framework was developed for nonlinear forced vibration of a cantilever beam using material nonlinearity (stress-strain nonlinearity). The resulting nonlinear equation was solved using method of multiple time scales to obtain the nonlinear frequency shifts. The present works focuses only on classical nonlinearity and, therefore, a diverse group of intact, classic nonlinear materials were chosen. The samples were tested using nonlinear resonance ultrasound spectroscopy, and the developed theory was used to invert the experimental frequency shifts to obtain the nonlinearity parameters. The third order elastic constants and β were calculated using their analytical relationship with the nonlinearity parameter. The experimentally determined C111 and β values for all various materials agree well with literature values. In addition to determining β, determination of the sign, or phase of β was also explored theoretically and experimentally.
Dipole-fiber systems: radiation field patterns, effective magnetic dipoles, and induced cavity modes
NASA Astrophysics Data System (ADS)
Atakaramians, Shaghik; Miroshnichenko, Andrey E.; Shadrivov, Ilya V.; Monro, Tanya M.; Kivshar, Yuri S.; Afshar, Shahraam V.
2015-12-01
We study the radiation patterns produced by a dipole placed at the surface of a nanofiber and oriented perpendicular to it, either along the radial (r-oriented) or azimuthal (Φ-oriented) directions. We find that the dipole induces an effective circular cavity-like leaky mode in the nanofiber. The first radiation peak of the Φ-oriented dipole contributes only to TE radiation modes, while the radiation of the r-oriented dipole is composed of both TE and TM radiation modes, with relative contribution depending on the refractive index of the nanofiber. We reveal that the field pattern of the first resonance of a Φ-oriented dipole is associated with a magnetic dipole mode and strong magnetic response of an optical nanofiber.
Role of the Permanent Dipole Moment in Coulomb Explosion
NASA Astrophysics Data System (ADS)
Zhang, Cai-Ping; Miao, Xiang-Yang
2013-10-01
By numerically solving the non-Born—Oppenheimer time-dependent Schrödinger equation in a few-cycle chirped laser field (5-fs, 800-nm), the effect of the permanent dipole moment on the Coulomb explosion is studied by the kinetic-energy-release spectra with the “virtual detector" method. The results indicate that with the effect of the permanent dipole moment, different multiphoton processes for heteronuclear and homonuclear diatomic molecular ions may take place when the wave packets transit from the ground state (1sσg) to the first excited state (2pσu), and then move along the excited potential curve, and finally charge-resonant enhanced ionization occurs at critical internuclear distance. As a result, despite the similar ionization probabilities for these two systems at higher vibrational level with larger chirp parameter β, the structure of the Coulomb explosion spectrum for the former is prominently different from that for the latter.
Elastic dipole response of spherical nuclei
Bastrukov, S.I.
1992-10-01
Within the framework of the nuclear fluid-dynamics the isoscalar dipole response of spherical nuclei is studied. Two kinds of elastic-like transverse oscillations of incompressible nucleus are found to be result in E1, T = 0 and M1, T = 0 spin-independent resonances. The isoscalar electric mode is accompanied by excitation in the nucleus volume of the torus-like current structure, known in the continuum theory as a poloidal dipole or spherical vortex of Hill. The dipole magnetic resonance belongs to the excitation of axially symmetric differential rotations. These motions are described by the toroidal dipole field harmonic in time. The estimates of energies and PWBA-computed form-factors for these modes are presented. 28 refs., 3 figs.
Symmetric Resonance Charge Exchange Cross Section Based on Impact Parameter Treatment
NASA Technical Reports Server (NTRS)
Omidvar, Kazem; Murphy, Kendrah; Atlas, Robert (Technical Monitor)
2002-01-01
Using a two-state impact parameter approximation, a calculation has been carried out to obtain symmetric resonance charge transfer cross sections between nine ions and their parent atoms or molecules. Calculation is based on a two-dimensional numerical integration. The method is mostly suited for hydrogenic and some closed shell atoms. Good agreement has been obtained with the results of laboratory measurements for the ion-atom pairs H+-H, He+-He, and Ar+-Ar. Several approximations in a similar published calculation have been eliminated.
Exact two-component relativistic theory for nuclear magnetic resonance parameters.
Sun, Qiming; Liu, Wenjian; Xiao, Yunlong; Cheng, Lan
2009-08-28
An exact two-component (X2C) relativistic theory for nuclear magnetic resonance parameters is obtained by first a single block-diagonalization of the matrix representation of the Dirac operator in a magnetic-field-dependent basis and then a magnetic perturbation expansion of the resultant two-component Hamiltonian and transformation matrices. Such a matrix formulation is not only simple but also general in the sense that the various ways of incorporating the field dependence can be treated in a unified manner. The X2C dia- and paramagnetic terms agree individually with the corresponding four-component ones up to machine accuracy for any basis.
2014-01-01
The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all six uttered Malay vowels are determined. Speech rehabilitation procedure demands some kind of visual perceivable prototype of speech articulation. To investigate the validity of the measured articulatory parameters based on acoustic theory of speech production, an acoustic analysis based on the uttered vowels by subjects has been performed. As the acoustic speech and articulatory parameters of uttered speech were examined, a correlation between formant frequencies and articulatory parameters was observed. The experiments reported a positive correlation between the constriction location of the tongue body and the first formant frequency, as well as a negative correlation between the constriction location of the tongue tip and the second formant frequency. The results demonstrate that the proposed method is an effective tool for the dynamic study of speech production. PMID:25060583
Zourmand, Alireza; Mirhassani, Seyed Mostafa; Ting, Hua-Nong; Bux, Shaik Ismail; Ng, Kwan Hoong; Bilgen, Mehmet; Jalaludin, Mohd Amin
2014-07-25
The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all six uttered Malay vowels are determined.Speech rehabilitation procedure demands some kind of visual perceivable prototype of speech articulation. To investigate the validity of the measured articulatory parameters based on acoustic theory of speech production, an acoustic analysis based on the uttered vowels by subjects has been performed. As the acoustic speech and articulatory parameters of uttered speech were examined, a correlation between formant frequencies and articulatory parameters was observed. The experiments reported a positive correlation between the constriction location of the tongue body and the first formant frequency, as well as a negative correlation between the constriction location of the tongue tip and the second formant frequency. The results demonstrate that the proposed method is an effective tool for the dynamic study of speech production.
The Resonator Impedance Model of Surface Roughness Applied to the LCLS Parameters
Bane, Karl LF
1999-03-19
The resonator impedance model of surface roughness in a cylindrical beam tube, derived in Ref. 1, is compared to the inductive impedance model of Ref. 2. It is shown that for long, smooth bunches the two models both give an inductive response, that the effective inductance per length is proportional to the corrugation depth over the beam pipe radius, and that the absolute results also are comparable. For a non-smooth bunch shape, such as is found in the undulator region of the LCLS, however, the inductive impedance model is no longer valid; and the resonator model gives a non-inductive response, with the induced energy spread decreasing much more slowly with increasing bunch length than for a smooth distribution. When applied to the actual bunch shape and parameters in the LCLS, the resonator model predicts that, to remain within tolerances for induced energy spread, the beam tube roughness must be kept to ~10 nm. Further calculations suggest, however, that if the period-to-depth aspect ratio of the surface features is large, (as has been found in recent measurements of polished beam tube surfaces), then the wake field effect may be greatly suppressed, and the roughness tolerance greatly increased.
The Resonator Impedance Model of Surface Roughness Applied to the LCLS Parameters
Bane, Karl LF.
1999-03-19
The resonator impedance model of surface roughness in a cylindrical beam tube, derived in Ref. 1, is compared to the inductive impedance model of Ref. 2. It is shown that for long, smooth bunches the two models both give an inductive response, that the effective inductance per length is proportional to the corrugation depth over the beam pipe radius, and that the absolute results also are comparable. For a non-smooth bunch shape, such as is found in the undulator region of the LCLS, however, the inductive impedance model is no longer valid; and the resonator model gives a non-inductive response, with the induced energy spread decreasing much more slowly with increasing bunch length than for a smooth distribution. When applied to the actual bunch shape and parameters in the LCLS, the resonator model predicts that, to remain within tolerances for induced energy spread, the beam tube roughness must be kept to 10 nm. Further calculations suggest, however, that if the period-to-depth aspect ratio of the surface features is large, (as has been found in recent measurements of polished beam tube surfaces), then the wake field effect may be greatly suppressed, and the roughness tolerance greatly increased.
Controlling magnetic and electric dipole modes in hollow silicon nanocylinders.
van de Haar, Marie Anne; van de Groep, Jorik; Brenny, Benjamin J M; Polman, Albert
2016-02-08
We propose a dielectric nanoresonator geometry consisting of hollow dielectric nanocylinders which support geometrical resonances. We fabricate such hollow Si particles with an outer diameter of 108-251 nm on a Si substrate, and determine their resonant modes with cathodo-luminescence (CL) spectroscopy and optical dark-field (DF) scattering measurements. The scattering behavior is numerically investigated in a systematic fashion as a function of wavelength and particle geometry. We find that the additional design parameter as a result of the introduction of a center gap can be used to control the relative spectral spacing of the resonant modes, which will enable additional control over the angular radiation pattern of the scatterers. Furthermore, the gap offers direct access to the enhanced magnetic dipole modal field in the center of the particle.
Dipole oscillations in fermionic mixtures
Chiacchiera, S.; Macri, T.; Trombettoni, A.
2010-03-15
We study dipole oscillations in a general fermionic mixture. Starting from the Boltzmann equation, we classify the different solutions in the parameter space through the number of real eigenvalues of the small oscillations matrix. We discuss how this number can be computed using the Sturm algorithm and its relation with the properties of the Laplace transform of the experimental quantities. After considering two components in harmonic potentials having different trapping frequencies, we study dipole oscillations in three-component mixtures. Explicit computations are done for realistic experimental setups using the classical Boltzmann equation without intraspecies interactions. A brief discussion of the application of this classification to general collective oscillations is also presented.
NASA Astrophysics Data System (ADS)
Sarikaya, Ebru Karakaş; Dereli, Ömer
2017-02-01
To obtain liquid phase molecular structure, conformational analysis of Orotic acid was performed and six conformers were determined. For these conformations, eight possible radicals were modelled by using Density Functional Theory computations with respect to molecular structure. Electron Paramagnetic Resonance parameters of these model radicals were calculated and then they were compared with the experimental ones. Geometry optimizations of the molecule and modeled radicals were performed using Becke's three-parameter hybrid-exchange functional combined with the Lee-Yang-Parr correlation functional of Density Functional Theory and 6-311++G(d,p) basis sets in p-dioxane solution. Because Orotic acid can be mutagenic in mammalian somatic cells and it is also mutagenic for bacteria and yeast, it has been studied.
NASA Astrophysics Data System (ADS)
Boreisho, A. S.; Lobachev, V. V.; Savin, A. V.; Strakhov, S. Yu; Trilis, A. V.
2007-07-01
The outlook is considered for the development of a high-power supersonic flowing chemical oxygen—iodine laser operating as an amplifier and controlled by radiation from a master oscillator by using an unstable resonator with a hole-coupled mirror. The influence of the seed radiation intensity, the coupling-hole diameter, the active-medium length, and the magnification factor on the parameters of laser radiation is analysed. It is shown that the use of such resonators is most advisable in medium-power oxygen—iodine lasers for which classical unstable resonators are inefficient because of their low magnification factors. The use of unstable resonators with a hole-coupled mirror and injection provides the control of radiation parameters and a considerable increase in the output power and brightness of laser radiation.
NASA Astrophysics Data System (ADS)
Egorova, Irina A.; Litvinova, Elena
2016-09-01
New results for electric dipole strength in the chain of even-even calcium isotopes with the mass numbers A =40 -54 are presented. Starting from the covariant Lagrangian of quantum hadrodynamics, spectra of collective vibrations (phonons) and phonon-nucleon coupling vertices for J ≤6 and natural parity were computed in a self-consistent relativistic quasiparticle random-phase approximation (RQRPA). These vibrations coupled to Bogoliubov two-quasiparticle configurations (2 q ⊗phonon ) formed the model space for the calculations of the dipole response function in the relativistic quasiparticle time blocking approximation. The calculations in the latter approach were performed for the giant dipole resonance (GDR) and compared to those obtained with the RQRPA and to available data. The evolution of the dipole strength with the neutron number is investigated for both high-frequency GDRs and low-lying strengths. The development of a pygmy resonant structure on the low-energy shoulder of the GDR is traced and analyzed in terms of transition densities. A dependence of the pygmy dipole strength on the isospin asymmetry parameter is extracted.
Derrien, H.; Leal, L.C.; Courcelle, A.; Santamarina, A.
2005-05-15
A new SAMMY analysis of the {sup 241}Pu resonance parameters from thermal to 20 eV is presented. This evaluation takes into account the trends given by integral experiments [post-irradiation experiments performed in French pressurized water reactors (PWRs)]. Compared to the previous evaluations performed by Derrien and de Saussure, the capture cross section increases especially in the 0.26-eV resonance. It is shown that the new resonance parameters proposed in this work improve the prediction of the {sup 242}Pu buildup in a PWR, which was significantly underestimated with the previous evaluations.
NASA Astrophysics Data System (ADS)
Masian, Y.; Sivak, A.; Sevostianov, D.; Vassiliev, V.; Velichansky, V.
The paper shows the presents results of studies of small-size rubidium cells with argon and neon buffer gases, produced by a patent pended technique of laser welding [Fishman et al. (2014)]. Cells were designed for miniature frequency standard. Temperature dependence of the frequency of the coherent population trapping (CPT) resonance was measured and used to optimize the ratio of partial pressures of buffer gases. The influence of duration and regime of annealing on the CPT-resonance frequency drift was investigated. The parameters of the FM modulation of laser current for two cases which correspond to the highest amplitude of CPT resonance and to the smallest light shifts of the resonance frequency were determined. The temperature dependences of the CPT resonance frequency were found to be surprisingly different in the two cases. A non-linear dependence of CPT resonance frequency on the temperature of the cell with the two extremes was revealed for one of these cases.
NASA Astrophysics Data System (ADS)
Günther, T.; Müller-Petke, M.
2012-04-01
For assessing the impact of climate changes on salinity of coastal aquifers, numerical modelling needs to be done. As input, the spatial distribution of the parameters porosity, hydraulic conductivity and salt concentrations is needed. Airborne resistivity data are available that gives hints to fluid conductivity. Magnetic resonance soundings (MRS) can provide free water content directly yielding porosity, which in turn is needed for fluid conductivities and thus TDS concentrations. Furthermore, hydraulic conductivities can be retrieved by empirical relations using porosity and decay times. For having a unique model with all three primary parameters, vertical electrical and magnetic resonance soundings are inverted jointly using a block discretization. The MRS data were preprocessed using noise cancellation, despiking and a new gate integration scheme. Data errors were derived from fitting and include the effect of gating. Since the resistivity model affects the MRS inversion but demands an extensive kernel calculation, resistivity is updated only once. After inversion, a systematic model variation is done in order to retrieve confidence intervals of the primary and secondary parameters. We apply the methodology to several soundings at the North Sea Island Borkum, where the dynamics of the fresh/salt water interface is currently investigated. All soundings exhibit a very good data quality. One sounding close to a research borehole verifies the approach qualitatively. Another sounding was done to calibrate the petrophysical parameters using a pumping test. Finally, it is applied to a sounding in the flooding area. Whereas single MRS and VES data can be explained by a 3-layer and 4-layer model, respectively, a 5-layer model is needed to find a comprehensive model. Even though porosities are fairly constant, we can distinguish lithology and salinity due to the combination of resistivity and decay time. This case shows two fresh/salt water interfaces separated by a
Costabel, Stephan; Yaramanci, Ugur
2013-01-01
[1] For characterizing water flow in the vadose zone, the water retention curve (WRC) of the soil must be known. Because conventional WRC measurements demand much time and effort in the laboratory, alternative methods with shortened measurement duration are desired. The WRC can be estimated, for instance, from the cumulative pore size distribution (PSD) of the investigated material. Geophysical applications of nuclear magnetic resonance (NMR) relaxometry have successfully been applied to recover PSDs of sandstones and limestones. It is therefore expected that the multiexponential analysis of the NMR signal from water-saturated loose sediments leads to a reliable estimation of the WRC. We propose an approach to estimate the WRC using the cumulative NMR relaxation time distribution and approximate it with the well-known van-Genuchten (VG) model. Thereby, the VG parameter n, which controls the curvature of the WRC, is of particular interest, because it is the essential parameter to predict the relative hydraulic conductivity. The NMR curves are calibrated with only two conventional WRC measurements, first, to determine the residual water content and, second, to define a fixed point that relates the relaxation time to a corresponding capillary pressure. We test our approach with natural and artificial soil samples and compare the NMR-based results to WRC measurements using a pressure plate apparatus and to WRC predictions from the software ROSETTA. We found that for sandy soils n can reliably be estimated with NMR, whereas for samples with clay and silt contents higher than 10% the estimation fails. This is the case when the hydraulic properties of the soil are mainly controlled by the pore constrictions. For such samples, the sensitivity of the NMR method for the pore bodies hampers a plausible WRC estimation. Citation: Costabel, S., and U. Yaramanci (2013), Estimation of water retention parameters from nuclear magnetic resonance relaxation time distributions, Water
Costabel, Stephan; Yaramanci, Ugur
2013-04-01
[1] For characterizing water flow in the vadose zone, the water retention curve (WRC) of the soil must be known. Because conventional WRC measurements demand much time and effort in the laboratory, alternative methods with shortened measurement duration are desired. The WRC can be estimated, for instance, from the cumulative pore size distribution (PSD) of the investigated material. Geophysical applications of nuclear magnetic resonance (NMR) relaxometry have successfully been applied to recover PSDs of sandstones and limestones. It is therefore expected that the multiexponential analysis of the NMR signal from water-saturated loose sediments leads to a reliable estimation of the WRC. We propose an approach to estimate the WRC using the cumulative NMR relaxation time distribution and approximate it with the well-known van-Genuchten (VG) model. Thereby, the VG parameter n, which controls the curvature of the WRC, is of particular interest, because it is the essential parameter to predict the relative hydraulic conductivity. The NMR curves are calibrated with only two conventional WRC measurements, first, to determine the residual water content and, second, to define a fixed point that relates the relaxation time to a corresponding capillary pressure. We test our approach with natural and artificial soil samples and compare the NMR-based results to WRC measurements using a pressure plate apparatus and to WRC predictions from the software ROSETTA. We found that for sandy soils n can reliably be estimated with NMR, whereas for samples with clay and silt contents higher than 10% the estimation fails. This is the case when the hydraulic properties of the soil are mainly controlled by the pore constrictions. For such samples, the sensitivity of the NMR method for the pore bodies hampers a plausible WRC estimation. Citation: Costabel, S., and U. Yaramanci (2013), Estimation of water retention parameters from nuclear magnetic resonance relaxation time distributions, Water
NASA Astrophysics Data System (ADS)
Petersen, Spencer J.; Basu, Soumyadipta; Raeymaekers, Bart; Francoeur, Mathieu
2013-11-01
The possibility of engineering near-field thermal radiative properties is investigated by adjusting design parameters of Mie resonance-based metamaterials. The sensitivities of surface polariton resonance frequencies, in both transverse magnetic and transverse electric polarizations, to parameters such as host medium relative permittivity and particle size and spacing (volume filling fraction) is determined. The sensitivity analysis is performed using a design of experiments method in combination with Mie resonance calculations and Clausius-Mossotti mixing relations. Particle size has the greatest effect on the resonance frequencies, while the volume filling fraction has the least. Based on the results from the sensitivity analysis, three metamaterials are selected for further analysis. The physics of these metamaterials is explored by calculating local density of electromagnetic states and surface polariton dispersion relation. As predicted by the sensitivity analysis, the local density of electromagnetic states and dispersion relation calculations show that Mie resonance-based metamaterials can be tuned to exhibit surface polariton resonance in the near-infrared spectrum. Energy density calculations show that surface polariton resonance in the near-infrared can be activated at temperatures as low as 800 K. Finally, a pathway to implementation of these metamaterials into macroscale engineering applications is proposed. Such metamaterials, with near-infrared surface polariton resonance, will significantly impact the development of nanoscale-gap thermophotovoltaic power generators for recycling waste heat into electricity.
Evaluation of the 235U resonance parameters to fit the standard recommended values
NASA Astrophysics Data System (ADS)
Leal, Luiz; Noguere, Gilles; Paradela, Carlos; Durán, Ignacio; Tassan-Got, Laurent; Danon, Yaron; Jandel, Marian
2017-09-01
A great deal of effort has been dedicated to the revision of the standard values in connection with the neutron interaction for some actinides. While standard data compilation are available for decades nuclear data evaluations included in existing nuclear data libraries (ENDF, JEFF, JENDL, etc.) do not follow the standard recommended values. Indeed, the majority of evaluations for major actinides do not conform to the standards whatsoever. In particular, for the n + 235U interaction the only value in agreement with the standard is the thermal fission cross section. A resonance re-evaluation of the n + 235U interaction has been performed to address the issues regarding standard values in the energy range from 10-5 eV to 2250 eV. Recently, 235U fission cross-section measurements have been performed at the CERN Neutron Time-of-Flight facility (TOF), known as n_TOF, in the energy range from 0.7 eV to 10 keV. The data were normalized according to the recommended standard of the fission integral in the energy range 7.8 eV to 11 eV. As a result, the n_TOF averaged fission cross sections above 100 eV are in good agreement with the standard recommended values. The n_TOF data were included in the 235U resonance analysis that was performed with the code SAMMY. In addition to the average standard values related to the fission cross section, standard thermal values for fission, capture, and elastic cross sections were also included in the evaluation. This paper presents the procedure used for re-evaluating the 235U resonance parameters including the recommended standard values as well as new cross section measurements.
Parameter analysis for a nuclear magnetic resonance gyroscope based on 133Cs-129Xe/131Xe
NASA Astrophysics Data System (ADS)
Zhang, Da-Wei; Xu, Zheng-Yi; Zhou, Min; Xu, Xin-Ye
2017-02-01
We theoretically investigate several parameters for the nuclear magnetic resonance gyroscope based on 133Cs-129Xe/131Xe. For a cell containing a mixture of 133Cs at saturated pressure, we investigate the optimal quenching gas (N2) pressure and the corresponding pump laser intensity to achieve 30% 133Cs polarization at the center of the cell when the static magnetic field B 0 is 5 {{μ }}{{T}} with different 129Xe/131Xe pressure. The effective field produced by spin-exchange polarized 129Xe or 131Xe sensed by 133Cs can also be discussed in different 129Xe/131Xe pressure conditions. Furthermore, the relationship between the detected signal and the probe laser frequency is researched. We obtain the optimum probe laser detuning from the D2 (6{}2{{S}}1/2\\to 6{}2{{P}}3/2) resonance with different 129Xe/131Xe pressure owing to the pressure broadening. Project supported by the National High Technology Research and Development Program of China (Grant No. 2014AA123401), the National Key Basic Research and Development Program of China (Grant Nos. 2016YFA0302103 and 2012CB821302), the National Natural Science Foundation of China (Grant 11134003), and Shanghai Excellent Academic Leaders Program of China (Grant No. 12XD1402400).
Leal, L.C.
2001-02-27
The R-matrix resonance analysis of experimental neutron transmission and cross sections of {sup 233}U, with the Reich-Moore Bayesian code SAMMY, was extended up to the neutron energy of 600 eV by taking advantage of new high resolution neutron transmission and fission cross section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA). The experimental data base is described. In addition to the microscopic data (time-of-flight measurements of transmission and cross sections), some experimental and evaluated integral quantities were included in the data base. Tabulated and graphical comparisons between the experimental data and the SAMMY calculated cross sections are given. The ability of the calculated cross sections to reproduce the effective multiplication factors k{sub eff} for various thermal, intermediate, and fast systems was tested. The statistical properties of the resonance parameters were examined and recommended values of the average s-wave resonance parameters are given.
NASA Astrophysics Data System (ADS)
Steinfeld, J. I.; Foy, B.; Hetzler, J.; Flannery, C.; Klaassen, J.; Mizugai, Y.; Coy, S.
1990-05-01
The spectroscopy of small to medium-size polyatomic molecules can be extremely complex, especially in higher-lying overtone and combination vibrational levels. The high density of levels also complicates the understanding of inelastic collision processes, which is required to model energy transfer and collision broadening of spectral lines. Both of these problems can be addressed by double-resonance spectroscopy, i.e., time-resolved pump-probe measurements using microwave, infrared, near-infrared, and visible-wavelength sources. Information on excited-state spectroscopy, transition moments, inelastic energy transfer rates and propensity rules, and pressure-broadening parameters may be obtained from such experiments. Examples are given for several species of importance in planetary atmospheres, including ozone, silane, ethane, and ammonia.
Neutron capture on Zr94: Resonance parameters and Maxwellian-averaged cross sections
NASA Astrophysics Data System (ADS)
Tagliente, G.; Milazzo, P. M.; Fujii, K.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Bisterzo, S.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapiço, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrari, A.; Ferreira-Marques, R.; Furman, W.; Gallino, R.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Jericha, E.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martínez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.
2011-07-01
The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus Zr90 and through Zr91,92,93,94, but only part of the flow extends to Zr96 because of the branching point at Zr95. Apart from their effect on the s-process flow, the comparably small isotopic (n,γ) cross sections make Zr also an interesting structural material for nuclear reactors. The Zr94 (n,γ) cross section has been measured with high resolution at the spallation neutron source n_TOF at CERN and resonance parameters are reported up to 60 keV neutron energy.
NASA Technical Reports Server (NTRS)
Steinfeld, J. I.; Foy, B.; Hetzler, J.; Flannery, C.; Klaassen, J.; Mizugai, Y.; Coy, S.
1990-01-01
The spectroscopy of small to medium-size polyatomic molecules can be extremely complex, especially in higher-lying overtone and combination vibrational levels. The high density of levels also complicates the understanding of inelastic collision processes, which is required to model energy transfer and collision broadening of spectral lines. Both of these problems can be addressed by double-resonance spectroscopy, i.e., time-resolved pump-probe measurements using microwave, infrared, near-infrared, and visible-wavelength sources. Information on excited-state spectroscopy, transition moments, inelastic energy transfer rates and propensity rules, and pressure-broadening parameters may be obtained from such experiments. Examples are given for several species of importance in planetary atmospheres, including ozone, silane, ethane, and ammonia.
Delbeke, Danaë; Bienstman, Peter; Bockstaele, Ronny; Baets, Roel
2002-05-01
We study the grating-assisted light-emitting diode, an LED design for high brightness based on a resonant cavity containing one- or two-dimensionally periodically corrugated layers (grating). We give in detail a generally applicable electromagnetic analysis based on the rigorous coupled-wave theory to calculate the extraction efficiency of spontaneous emission in a periodically corrugated layer structure. This general model is then specified on the grating-assisted resonant-cavity LED, showing simulated efficiencies of more than 40%.
Dipole strength from first principles calculations
NASA Astrophysics Data System (ADS)
Miorelli, Mirko; Bacca, Sonia; Barnea, Nir; Hagen, Gaute; Jansen, Gustav R.; Papenbrock, Thomas; Orlandini, Giuseppina
2016-09-01
The electric dipole polarizability quantifies the low-energy behavior of the dipole strength. It is related to the proton and neutron distributions of the nucleus, and thereby can be used to constrain the neutron equation of state and the physics of neutron stars. Only recently however, new developments in ab initio methods finally allowed first principles studies of the dipole strength in medium-mass nuclei. Using the Lorentz integral transform coupled cluster method with the newly developed chiral interaction NNLOsat we study the low energy behavior of the dipole strength in 4He, 16O and 22O. For the exotic 22O we observe large contributions to the dipole strength at very low energy, indicating the presence of a pygmy dipole resonance, in agreement with what experimentally found by Leistenschneider et al.. We then study correlations between the electric dipole polarizability and the charge radius in 16O and 40Ca using a variety of realistic Hamiltonians, showing the importance of three-nucleon forces. We aknowledge NRC and NSERC.
NASA Astrophysics Data System (ADS)
Ryazantsev, S. N.; Skobelev, I. Yu; Faenov, A. Ya; Pikuz, T. A.; Grum-Grzhimailo, A. N.; Pikuz, S. A.
2016-11-01
While the plasma created by powerful laser expands from the target surface it becomes overcooled, i.e. recombining one. Improving of diagnostic methods applicable for such plasma is rather important problem in laboratory astrophysics nowadays because laser produced jets are fully scalable to young stellar objects. Such scaling is possible because of the plasma hydrodynamic equations invariance under some transformations. In this paper it is shown that relative intensities of the resonance transitions in He-like ions can be used to measure the parameters of recombining plasma. Intensity of the spectral lines corresponding to these transitions is sensitive to the density in the range of 1016-1020 cm-3 while the temperature ranges from 10 to 100 eV for ions with nuclear charge Zn ∼ 10. Calculations were carried out for F VIII ion and allowed to determine parameters of plasma jets created by nanosecond laser system ELFIE (Ecole Polytechnique, France) for astrophysical phenomenon modelling. Obtained dependencies are quite universal and can be used for any recombining plasma containing He-like fluorine ions.
n+235U resonance parameters and neutron multiplicities in the energy region below 100 eV
NASA Astrophysics Data System (ADS)
Pigni, Marco T.; Capote, Roberto; Trkov, Andrej; Pronyaev, Vladimir G.
2017-09-01
In August 2016, following the recent effort within the Collaborative International Evaluated Library Organization (CIELO) pilot project to improve the neutron cross sections of 235U, Oak Ridge National Laboratory (ORNL) collaborated with the International Atomic Energy Agency (IAEA) to release a resonance parameter evaluation. This evaluation restores the performance of the evaluated cross sections for the thermal- and above-thermal-solution benchmarks on the basis of newly evaluated thermal neutron constants (TNCs) and thermal prompt fission neutron spectra (PFNS). Performed with support from the US Nuclear Criticality Safety Program (NCSP) in an effort to provide the highest fidelity general purpose nuclear database for nuclear criticality applications, the resonance parameter evaluation was submitted as an ENDF-compatible file to be part of the next release of the ENDF/B-VIII.0 nuclear data library. The resonance parameter evaluation methodology used the Reich-Moore approximation of the R-matrix formalism implemented in the code SAMMY to fit the available time-of-flight (TOF) measured data for the thermal induced cross section of n+235U up to 100 eV. While maintaining reasonably good agreement with the experimental data, the validation analysis focused on restoring the benchmark performance for 235U solutions by combining changes to the resonance parameters and to the prompt resonance v̅
Li, Xin; Pierce, Donna M; Arnoldus, Henk F
2011-05-01
When a circular electric dipole moment, rotating in the x-y plane, is embedded in a material with relative permittivity ε(r) and relative permeability μ(r), the field lines of energy flow of the emitted radiation are dramatically influenced by the surrounding material. For emission in free space, the field lines swirl around the z axis and lie on a cone. The direction of rotation of the field lines around the z axis is the same as the direction of rotation of the dipole moment. We found that when the real part of ε(r) is negative, the rotation of the field lines changes direction, and hence the energy counter-rotates the dipole moment. When there is damping in the material, due to an imaginary part of ε(r), the cone turns into a funnel, and the density of the field lines diminishes near the location of the source. In addition, all radiation is emitted along the z axis and the x-y plane, whereas for emission in free space, the radiation is emitted in all directions. It is also shown that the displacement of the dipole image in the far field depends on the material parameters and that the shift can be much larger than the shift of the image in free space.
Axion induced oscillating electric dipole moments
Hill, Christopher T.
2015-06-24
In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency ma and strength ~ 10-32 e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.
Axion induced oscillating electric dipole moments
Hill, Christopher T.
2015-06-24
In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency m_{a} and strength ~ 10^{-32} e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.
NASA Astrophysics Data System (ADS)
Sutter, Kiplangat
This thesis illustrates the utilization of Density functional theory (DFT) in calculations of gas and solution phase Nuclear Magnetic Resonance (NMR) properties of light and heavy nuclei. Computing NMR properties is still a challenge and there are many unknown factors that are still being explored. For instance, influence of hydrogen-bonding; thermal motion; vibration; rotation and solvent effects. In one of the theoretical studies of 195Pt NMR chemical shift in cisplatin and its derivatives illustrated in Chapter 2 and 3 of this thesis. The importance of representing explicit solvent molecules explicitly around the Pt center in cisplatin complexes was outlined. In the same complexes, solvent effect contributed about half of the J(Pt-N) coupling constant. Indicating the significance of considering the surrounding solvent molecules in elucidating the NMR measurements of cisplatin binding to DNA. In chapter 4, we explore the Spin-Orbit (SO) effects on the 29Si and 13C chemical shifts induced by surrounding metal and ligands. The unusual Ni, Pd, Pt trends in SO effects to the 29Si in metallasilatrane complexes X-Si-(mu-mt)4-M-Y was interpreted based on electronic and relativistic effects rather than by structural differences between the complexes. In addition, we develop a non-linear model for predicting NMR SO effects in a series of organics bonded to heavy nuclei halides. In chapter 5, we extend the idea of "Chemist's orbitals" LMO analysis to the quantum chemical proton NMR computation of systems with internal resonance-assisted hydrogen bonds. Consequently, we explicitly link the relationship between the NMR parameters related to H-bonded systems and intuitive picture of a chemical bond from quantum calculations. The analysis shows how NMR signatures characteristic of H-bond can be explained by local bonding and electron delocalization concepts. One shortcoming of some of the anti-cancer agents like cisplatin is that they are toxic and researchers are looking for
NASA Astrophysics Data System (ADS)
Coon, Joshua
Magnetic Resonance guided High Intensity Focused Ultrasound (MRgHIFU) treatments are a promising modality for cancer treatments in which a focused beam of ultrasound energy is used to kill tumor tissue. However, obstacles still exist to its widespread clinical implementation, including long treatment times. This research demonstrates reductions in treatment times through intelligent selection of the user-controllable parameters, including: the focal zone treatment path, focal zone size, focal zone spacing, and whether to treat one or several focal zone locations at any given time. Several treatments using various combinations of these parameters were simulated using a finite difference method to solve the Pennes bio-heat transfer equation for an ultrasonically heated tissue region with a wide range of acoustic, thermal, geometric, and tumor properties. The total treatment time was iteratively optimized using either a heuristic method or routines included in the Matlab software package, with constraints imposed for patient safety and treatment efficacy. The results demonstrate that large reductions in treatment time are possible through the intelligent selection of user-controllable treatment parameters. For the treatment path, treatment times are reduced by as much as an order of magnitude if the focal zones are arranged into stacks along the axial direction and a middle-front-back ordering is followed. For situations where normal tissue heating constraints are less stringent, these focal zones should have high levels of adjacency to further decrease treatment times; however, adjacency should be reduced in some cases where normal tissue constraints are more stringent. Also, the use of smaller, more concentrated focal zones produces shorter treatment times than larger, more diluted focal zones, a result verified in an agar phantom model. Further, focal zones should be packed using only a small amount of overlap in the axial direction and with a small gap in the
Can the electron magnetic resonance (EMR) techniques measure the crystal (ligand) field parameters?
NASA Astrophysics Data System (ADS)
Rudowicz, C.; Sung, H. W. F.
2001-07-01
In this paper, the question posed in the title is critically examined on the basis of the available literature evidence implying the positive answer. The distinction between, on the one hand, the actual crystal field (CF) or equivalently ligand field (LF) related quantities and, on the other hand, the actual zero-field splitting (ZFS) or equivalently fine structure (FS) quantities, is elucidated. The origin and possible roots of the incorrect terminology consisting in mixing up the two physically distinct quantities at different levels are examined. Aspects concerning Hamiltonians, parameters, energy level splitting, and nature of the operators involved are taken into account. Problems with the various notations for the operators and parameters used in the electron magnetic resonance (EMR) area are also identified and reviewed. A large number of cases of incorrect terminology and other inconsistencies identified in the course of a comprehensive literature survey are analyzed and systematically classified. Implications of the confusion in question, which go beyond the simple semantic issues, are discussed. The results of the survey reveal that the two most serious categories of this confusion lead to misinterpretation of the experimental EMR data. Several examples of serious misinterpretations found in the books, reviews, and original papers are discussed. The incorrect terminology contributes also to misleading keyword classifications of papers in journals as well as references in scientific literature databases. Thus, the database searches may produce unreliable outcomes. Examples of such outcomes are also shown. It is concluded that, in order to prevent further proliferation of the incorrect terminology and thus to increase reliability of the published EMR data, a concerted effort within the EMR community is indispensable. Various ways in this regard at the international level are suggested.
Al-Radaideh, Ali; Tayyem, Reema; Al-Fayomi, Kholoud; Nimer, Nisreen; Malkawi, Amer; Al-Zu Bi, Rana; Agraib, Lana; Athamneh, Imad; Hijjawi, Nawal
2016-12-01
To measure the abdominal subcutaneous fat (SF) and visceral fat (VF) volumes using high-field magnetic resonance imaging (MRI) and to investigate their association with selected anthropometric and biochemical parameters among obese and nonobese apparently healthy participants. A cross-sectional study was conducted by recruiting 167 healthy participants. Abdominal scans were acquired at 3T MRI, and the SF and VF were segmented and their volumes were calculated. Selected anthropometric and biochemical measurements were also determined. A significant difference (P < 0.05) was observed between normal body weight and overweight and obese participants for SF and VF, total abdominal fat volumes, leptin, resistin, adiponectin and waist circumference. Waist circumferences were measured by tape and MRI. Findings revealed that MRI-measured fat volumes were different between males and females and had a significant (P < 0.01) strong positive correlation with body mass index, leptin, resistin and WC and had a negative correlation with adiponectin level. MRI-measured fat volumes were found to correlate moderately with interleukin-6 and weakly with cholesterol, serum triglyceride and low-density lipoprotein. Except for cholesterol, all measured biochemical variables and abdominal fat volumes in the current study were significantly associated with body mass index. All anthropometric and biochemical parameters showed weak-to-strong associations with the MRI-measured fat volumes. Abdominal fat distribution was different between males and females and their correlations with some lipid profiles were found to be sex dependent. These findings revealed that MRI can be used as an alternative tool for obesity assessment. Copyright Â© 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.
Crossing resonance of wave fields in a medium with an inhomogeneous coupling parameter
NASA Astrophysics Data System (ADS)
Ignatchenko, V. A.; Polukhin, D. S.
2013-11-01
The dynamic susceptibilities (Green's functions) of the system of two coupled wave fields of different physical natures in a medium with an arbitrary relation between the mean value ɛ and rms fluctuation Δɛ of the coupling parameter have been examined. The self-consistent approximation involving all diagrams with noncrossing correlation lines has been developed for the case where the initial Green's function of the homogeneous medium describes the system of coupled wave fields. The analysis has been performed for spin and elastic waves. Expressions have been obtained for the diagonal elements G mm and G uu of the matrix Green's function, which describe spin and elastic waves in the case of magnetic and elastic excitations, and for the off-diagonal elements G mu and G um , which describe these waves in the case of cross excitation. Change in the forms of these elements has been numerically studied for the case of one-dimensional inhomogeneities with an increase in Δɛ and with a decrease in ɛ under the condition that the sum of the squares of these quantities is conserved: two peaks in the frequency dependences of imaginary parts of G mm and G uu are broadened and then joined into one broad peak; a fine structure appears in the form of narrow resonance at the vertex of the Green's function of one wave field and narrow antiresonance at the vertex of the Green's function of the other field; peaks of the fine structure are broadened and then disappear with an increase in the correlation wavenumber of the inhomogeneities of the coupling parameter; and the amplitudes of the off-diagonal elements vanish in the limit ɛ → 0.
Crossing resonance of wave fields in a medium with an inhomogeneous coupling parameter
Ignatchenko, V. A. Polukhin, D. S.
2013-11-15
The dynamic susceptibilities (Green functions) of the system of two coupled wave fields of different physical natures in a medium with an arbitrary relation between the mean value ε and rms fluctuation Δε of the coupling parameter have been examined. The self-consistent approximation involving all diagrams with noncrossing correlation lines has been developed for the case where the initial Green’s function of the homogeneous medium describes the system of coupled wave fields. The analysis has been performed for spin and elastic waves. Expressions have been obtained for the diagonal elements G{sub mm} and G{sub uu} of the matrix Green’s function, which describe spin and elastic waves in the case of magnetic and elastic excitations, and for the off-diagonal elements G{sub mu} and G{sub um}, which describe these waves in the case of cross excitation. Change in the forms of these elements has been numerically studied for the case of one-dimensional inhomogeneities with an increase in Δε and with a decrease in ε under the condition that the sum of the squares of these quantities is conserved: two peaks in the frequency dependences of imaginary parts of G{sub mm} and G{sub uu} are broadened and then joined into one broad peak; a fine structure appears in the form of narrow resonance at the vertex of the Green’s function of one wave field and narrow antiresonance at the vertex of the Green function of the other field; peaks of the fine structure are broadened and then disappear with an increase in the correlation wavenumber of the inhomogeneities of the coupling parameter; and the amplitudes of the off-diagonal elements vanish in the limit ε → 0.
Variability of Schumann resonance parameters observed at low latitude stations in China
NASA Astrophysics Data System (ADS)
Ouyang, X.-Y.; Xiao, Z.; Hao, Y.-Q.; Zhang, D.-H.
2015-10-01
This paper presents a comprehensive analysis of the Schumann resonance (SR) parameters observed at low latitude stations in China for the first time. Variations of SR peak frequency and intensity on different timescales (from minutes to years) are analyzed in detail. Diurnal and seasonal variations are shown and the source-observer distance is calculated to confirm the contributions of lightning activity. Differences in the profiles of SR intensity between the NS and EW components are due to the effects of the source-observer distance and the relative position of the observer to the sources. Diurnal frequency variations are more complicated and cannot be directly linked with the three thunderstorm centers. Seasonal variations are clear for intensity but not for frequency. The differences in the diurnal and seasonal variations between the SR intensity and frequency show that the greatest contributor to SR intensity is global lightning activity, while the SR frequency is not affected solely by lightning, as certain other factors involving ionosphere properties may play non-negligible roles. We also emphasize that our observations do not show a distinct day-night change in the SR parameters, and that the SR intensity does not show abrupt changes across terminators. This observation is consistent with previous simulations. Finally, the response of the SR to a solar flare is discussed. The flare leads to a sudden increase of about 0.2 Hz relative to the 2σ level of the SR frequencies in the first three modes, which is in agreement with other works in the literature. This frequency enhancement is explained using theoretical calculations.
Measurement of Resonance Parameters of Orbitally Excited Narrow B^0 Mesons
Aaltonen, : T.
2008-09-01
The authors report a measurement of resonance parameters of the orbitally excited (L = 1) narrow B{sup 0} mesons in decays to B{sup (*)+}{pi}{sup -} using 1.7 fb{sup -1} of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the B*{sub 2}{sup 0} state are measured to be m(B*{sub 2}{sup 0}) = 5740.2{sub -1.8}{sup +1.7}(stat.){sub -0.8}{sup +0.9}(syst.) MeV/c{sup 2} and {Lambda}(B*{sub 2}{sup 0}) = 22.7{sub -3.2}{sup +3.8}(stat.){sub -10.2}{sup +3.2}(syst.) MeV/c{sub 2}. The mass difference between the B*{sub 2}{sup 0} and B{sub 1}{sup 0} states is measured to be 14.9{sub -2.5}{sup +2.2}(stat.){sub -1.4}{sup +1.2}(syst.) MeV/c{sup 2}, resulting in a B{sub 1}{sup 0} mass of 5725.3{sub -2.2}{sup +1.6}(stat.){sub -1.5}{sup +1.4}(syst.) MeV/c{sup 2}. This is currently the most precise measurement of the masses of these states and the first measurement of the B*{sub 2}{sup 0} width.
Comprehensive Amm242 neutron-induced reaction cross sections and resonance parameters
NASA Astrophysics Data System (ADS)
Buckner, M. Q.; Wu, C. Y.; Henderson, R. A.; Bucher, B.; Wimer, N.; Chyzh, A.; Bredeweg, T. A.; Baramsai, B.; Couture, A.; Jandel, M.; Mosby, S.; Ullmann, J. L.
2017-06-01
The 242Am metastable isomer's neutron-induced destruction mechanisms were studied at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array with a compact parallel-plate avalanche counter. New Amm242 neutron-capture cross sections were determined from 100 meV to 10 keV, and the absolute scale was set with respect to a concurrent measurement of the well-known Amm242 neutron-induced-fission cross section. The new fission cross section spans an energy range from 100 meV to 1 MeV and was normalized to the ENDF/B-VII.1 evaluated cross section to set the absolute scale. Our Amm242(n ,f ) cross section agrees well with the cross section of Browne et al. [Phys. Rev. C 29, 2188 (1984)], 10.1103/PhysRevC.29.2188 over this large energy interval. The new neutron-capture cross section measurement complements and agrees well with our recent results reported below 1 eV in Buckner et al. [Phys. Rev. C 95, 024610 (2017)], 10.1103/PhysRevC.95.024610. This new work comprises the most comprehensive study of Amm242(n ,γ ) above thermal energy. Neutron-induced resonance energies and parameters were deduced with the sammy R -matrix code for incident neutron energies up to 45 eV, and the new average Γγ is 13 % higher than the evaluated average γ width.
A Mathematical Assessment of the Precision of Parameters in Measuring Resonance Spectra
NASA Astrophysics Data System (ADS)
Golding, Elke M.; Golding, Raymund M.
1998-12-01
The accurate interpretation ofin vivomagnetic resonance spectroscopy (MRS) spectra requires a complete understanding of the associated noise-induced errors. In this paper, we address the effect of complex correlated noise patterns on the measurement of a set ofpeakparameters. This is examined initially at the level of a single spectral analysis followed by addressing the noise-induced errors associated with determining thesignalparameters from thepeakparameters. We describe a relatively simple method for calculating these errors for any correlated noise pattern in terms of the noise standard deviation and correlation length. The results are presented in such a way that an estimate of the errors may be made from a single MRS spectrum. We also explore how, under certain circumstances, the lineshape of the signal may be determined. We then apply these results to reexamine a set ofin vivo31P MRS spectra obtained from rat brain prior to and following moderate fluid percussion injury. The approach outlined in this paper will demonstrate how meaningful results may be obtained from spectra where the signal-to-noise ratio (SNR) is quite small and where knowledge of the precise shape of the signal and the detail of the noise pattern is unknown. In essence, we show how to determine the expected errors in the spectral parameters from an estimate of the SNR from a single spectrum, thereby allowing a more discriminative interpretation of the data.
Measurement of resonance parameters of orbitally excited narrow B0 mesons.
Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; González, B Alvarez; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzurri, P; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Beecher, D; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Beringer, J; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burke, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Calancha, C; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Chwalek, T; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cordelli, M; Cortiana, G; Cox, C A; Cox, D J; Crescioli, F; Almenar, C Cuenca; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lorenzo, G; Dell'orso, M; Deluca, C; Demortier, L; Deng, J; Deninno, M; Derwent, P F; di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Elagin, A; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Frank, M J; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; 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Wynne, S M; Xie, S; Yagil, A; Yamamoto, K; Yamaoka, J; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zhang, X; Zheng, Y; Zucchelli, S
2009-03-13
We report a measurement of resonance parameters of the orbitally excited (L=1) narrow B0 mesons in decays to B;{(*)+}pi;{-} using 1.7 fb;{-1} of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the B_{2};{*0} state are measured to be m(B_{2};{*0})=5740.2_{-1.8};{+1.7}(stat)-0.8+0.9(syst) MeV/c;{2} and Gamma(B_{2};{*0})=22.7_{-3.2};{+3.8}(stat)-10.2+3.2(syst) MeV/c;{2}. The mass difference between the B_{2};{*0} and B10 states is measured to be 14.9_{-2.5};{+2.2}(stat)-1.4+1.2(syst) MeV/c;{2}, resulting in a B10 mass of 5725.3_{-2.2};{+1.6}(stat)-1.5+1.4(syst) MeV/c;{2}. This is currently the most precise measurement of the masses of these states and the first measurement of the B_{2};{*0} width.
Weijo, Ville; Bast, Radovan; Manninen, Pekka; Saue, Trond; Vaara, Juha
2007-02-21
We examine the quantum chemical calculation of parity-violating (PV) electroweak contributions to the spectral parameters of nuclear magnetic resonance (NMR) from a methodological point of view. Nuclear magnetic shielding and indirect spin-spin coupling constants are considered and evaluated for three chiral molecules, H2O2, H2S2, and H2Se2. The effects of the choice of a one-particle basis set and the treatment of electron correlation, as well as the effects of special relativity, are studied. All of them are found to be relevant. The basis-set dependence is very pronounced, especially at the electron correlated ab initio levels of theory. Coupled-cluster and density-functional theory (DFT) results for PV contributions differ significantly from the Hartree-Fock data. DFT overestimates the PV effects, particularly with nonhybrid exchange-correlation functionals. Beginning from third-row elements, special relativity is of importance for the PV NMR properties, shown here by comparing perturbational one-component and various four-component calculations. In contrast to what is found for nuclear magnetic shielding, the choice of the model for nuclear charge distribution--point charge or extended (Gaussian)--has a significant impact on the PV contribution to the spin-spin coupling constants.
Measurement of Resonance Parameters of Orbitally Excited Narrow B0 Mesons
NASA Astrophysics Data System (ADS)
Aaltonen, T.; Adelman, J.; Akimoto, T.; Albrow, M. G.; González, B. Álvarez; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Apresyan, A.; Arisawa, T.; Artikov, A.; Ashmanskas, W.; Attal, A.; Aurisano, A.; Azfar, F.; Azzurri, P.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Bartsch, V.; Bauer, G.; Beauchemin, P.-H.; Bedeschi, F.; Beecher, D.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Beringer, J.; Bhatti, A.; Binkley, M.; Bisello, D.; Bizjak, I.; Blair, R. E.; Blocker, C.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Boisvert, V.; Bolla, G.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brau, B.; Bridgeman, A.; Brigliadori, L.; Bromberg, C.; Brubaker, E.; Budagov, J.; Budd, H. S.; Budd, S.; Burke, S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Byrum, K. L.; Cabrera, S.; Calancha, C.; Campanelli, M.; Campbell, M.; Canelli, F.; Canepa, A.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chang, S. H.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chou, J. P.; Choudalakis, G.; Chuang, S. H.; Chung, K.; Chung, W. H.; Chung, Y. S.; Chwalek, T.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clark, D.; Compostella, G.; Convery, M. E.; Conway, J.; Cordelli, M.; Cortiana, G.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Almenar, C. Cuenca; Cuevas, J.; Culbertson, R.; Cully, J. C.; Dagenhart, D.; Datta, M.; Davies, T.; de Barbaro, P.; de Cecco, S.; Deisher, A.; de Lorenzo, G.; Dell'Orso, M.; Deluca, C.; Demortier, L.; Deng, J.; Deninno, M.; Derwent, P. F.; di Giovanni, G. P.; Dionisi, C.; di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Donini, J.; Dorigo, T.; Dube, S.; Efron, J.; Elagin, A.; Erbacher, R.; Errede, D.; Errede, S.; Eusebi, R.; Fang, H. C.; Farrington, S.; Fedorko, W. T.; Feild, R. G.; Feindt, M.; Fernandez, J. P.; Ferrazza, C.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Furic, I.; Gallinaro, M.; Galyardt, J.; Garberson, F.; Garcia, J. E.; Garfinkel, A. F.; Genser, K.; Gerberich, H.; Gerdes, D.; Gessler, A.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Gimmell, J. L.; Ginsburg, C. M.; Giokaris, N.; Giordani, M.; Giromini, P.; Giunta, M.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gresele, A.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Grundler, U.; da Costa, J. Guimaraes; Gunay-Unalan, Z.; Haber, C.; Hahn, K.; Hahn, S. R.; Halkiadakis, E.; Han, B.-Y.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harper, S.; Harr, R. F.; Harris, R. M.; Hartz, M.; Hatakeyama, K.; Hays, C.; Heck, M.; Heijboer, A.; Heinrich, J.; Henderson, C.; Herndon, M.; Heuser, J.; Hewamanage, S.; Hidas, D.; Hill, C. S.; Hirschbuehl, D.; Hocker, A.; Hou, S.; Houlden, M.; Hsu, S.-C.; Huffman, B. T.; Hughes, R. E.; Husemann, U.; Huston, J.; Incandela, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jayatilaka, B.; Jeon, E. J.; Jha, M. K.; Jindariani, S.; Johnson, W.; Jones, M.; Joo, K. K.; Jun, S. Y.; Jung, J. E.; Junk, T. R.; Kamon, T.; Kar, D.; Karchin, P. E.; Kato, Y.; Kephart, R.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, H. W.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kimura, N.; Kirsch, L.; Klimenko, S.; Knuteson, B.; Ko, B. R.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Korytov, A.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Krumnack, N.; Kruse, M.; Krutelyov, V.; Kubo, T.; Kuhr, T.; Kulkarni, N. P.; Kurata, M.; Kusakabe, Y.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; Lazzizzera, I.; Lecompte, T.; Lee, E.; Lee, H. S.; Lee, S. W.; Leone, S.; Lewis, J. D.; Lin, C.-S.; Linacre, J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, T.; Lockyer, N. S.; Loginov, A.; Loreti, M.; Lovas, L.; Lucchesi, D.; Luci, C.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lyons, L.; Lys, J.; Lysak, R.; MacQueen, D.; Madrak, R.; Maeshima, K.; Makhoul, K.; Maki, T.; Maksimovic, P.; Malde, S.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Marino, C. P.; Martin, A.; Martin, V.; Martínez, M.; Martínez-Ballarín, R.; Maruyama, T.; Mastrandrea, P.; Masubuchi, T.; Mathis, M.; Mattson, M. E.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Menzione, A.; Merkel, P.; Mesropian, C.; Miao, T.; Miladinovic, N.; Miller, R.; Mills, C.; Milnik, M.; Mitra, A.; Mitselmakher, G.; Miyake, H.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlok, J.; Fernandez, P. Movilla; Mülmenstädt, J.; Mukherjee, A.; Muller, Th.; Mumford, R.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Nagano, A.; Naganoma, J.; Nakamura, K.; Nakano, I.; Napier, A.; Necula, V.; Nett, J.; Neu, C.; Neubauer, M. S.; Neubauer, S.; Nielsen, J.; Nodulman, L.; Norman, M.; Norniella, O.; Nurse, E.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Griso, S. Pagan; Palencia, E.; Papadimitriou, V.; Papaikonomou, A.; Paramonov, A. A.; Parks, B.; Pashapour, S.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Peiffer, T.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pinera, L.; Pitts, K.; Plager, C.; Pondrom, L.; Poukhov, O.; Pounder, N.; Prakoshyn, F.; Pronko, A.; Proudfoot, J.; Ptohos, F.; Pueschel, E.; Punzi, G.; Pursley, J.; Rademacker, J.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Rekovic, V.; Renton, P.; Renz, M.; Rescigno, M.; Richter, S.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Rossi, M.; Rossin, R.; Roy, P.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.; Sakumoto, W. K.; Saltó, O.; Santi, L.; Sarkar, S.; Sartori, L.; Sato, K.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, A.; Schmidt, E. E.; Schmidt, M. A.; Schmidt, M. P.; Schmitt, M.; Schwarz, T.; Scodellaro, L.; Scribano, A.; Scuri, F.; Sedov, A.; Seidel, S.; Seiya, Y.; Semenov, A.; Sexton-Kennedy, L.; Sforza, F.; Sfyrla, A.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shiraishi, S.; Shochet, M.; Shon, Y.; Shreyber, I.; Sidoti, A.; Sinervo, P.; Sisakyan, A.; Slaughter, A. J.; Slaunwhite, J.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Snihur, R.; Soha, A.; Somalwar, S.; Sorin, V.; Spalding, J.; Spreitzer, T.; Squillacioti, P.; Stanitzki, M.; St. Denis, R.; Stelzer, B.; Stelzer-Chilton, O.; Stentz, D.; Strologas, J.; Strycker, G. L.; Stuart, D.; Suh, J. S.; Sukhanov, A.; Suslov, I.; Suzuki, T.; Taffard, A.; Takashima, R.; Takeuchi, Y.; Tanaka, R.; Tecchio, M.; Teng, P. K.; Terashi, K.; Thom, J.; Thompson, A. S.; Thompson, G. A.; Thomson, E.; Tipton, P.; Ttito-Guzmán, P.; Tkaczyk, S.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Tourneur, S.; Trovato, M.; Tsai, S.-Y.; Tu, Y.; Turini, N.; Ukegawa, F.; Vallecorsa, S.; van Remortel, N.; Varganov, A.; Vataga, E.; Vázquez, F.; Velev, G.; Vellidis, C.; Veszpremi, V.; Vidal, M.; Vidal, R.; Vila, I.; Vilar, R.; Vine, T.; Vogel, M.; Volobouev, I.; Volpi, G.; Wagner, P.; Wagner, R. G.; Wagner, R. L.; Wagner, W.; Wagner-Kuhr, J.; Wakisaka, T.; Wallny, R.; Wang, S. M.; Warburton, A.; Waters, D.; Weinberger, M.; Weinelt, J.; Wester, W. C., III; Whitehouse, B.; Whiteson, D.; Wicklund, A. B.; Wicklund, E.; Wilbur, S.; Williams, G.; Williams, H. H.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, C.; Wright, T.; Wu, X.; Würthwein, F.; Wynne, S. M.; Xie, S.; Yagil, A.; Yamamoto, K.; Yamaoka, J.; Yang, U. K.; Yang, Y. C.; Yao, W. M.; Yeh, G. P.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Yu, S. S.; Yun, J. C.; Zanello, L.; Zanetti, A.; Zhang, X.; Zheng, Y.; Zucchelli, S.
2009-03-01
We report a measurement of resonance parameters of the orbitally excited (L=1) narrow B0 mesons in decays to B(*)+π- using 1.7fb-1 of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the B2*0 state are measured to be m(B2*0)=5740.2-1.8+1.7(stat)-0.8+0.9(syst)MeV/c2 and Γ(B2*0)=22.7-3.2+3.8(stat)-10.2+3.2(syst)MeV/c2. The mass difference between the B2*0 and B10 states is measured to be 14.9-2.5+2.2(stat)-1.4+1.2(syst)MeV/c2, resulting in a B10 mass of 5725.3-2.2+1.6(stat)-1.5+1.4(syst)MeV/c2. This is currently the most precise measurement of the masses of these states and the first measurement of the B2*0 width.
NASA Astrophysics Data System (ADS)
Afanasyev, Y. D.
2006-03-01
Evolution of a two-dimensional flow induced by a jet ejected from a nozzle of finite size is studied experimentally. Vortex dipole forms at the front of the developing flow while a trailing jet establishes behind the dipole. The dynamics of the flow is discussed on the basis of detailed measurements of vorticity and velocity fields which are obtained using particle image velocimetry. It is found that dipoles do not separate (pinch-off) from the trailing jet for values of the stroke ratio up to 15, which fact can be contrasted with the behavior of vortex rings reported previously by other authors. A characteristic time scale that is defined differently from the formation time of vortex rings can be introduced. This time scale (startup time) indicates the moment when the dipole starts translating after an initial period when it mainly grows absorbing the jet from the nozzle. A simple model that considers the competing effects of expansion and translation is developed to obtain an estimate of the dimensionless startup time. The dynamics of a dipole after the formation is characterized by a reduced flux of vorticity from the jet. The dipole moves forward with constant speed such that a value of the ratio of the speed of propagation of the dipole to the mean velocity of the jet is found to be 0.5. A universality of this ratio is explained in the framework of a model based on conservation of mass and momentum for the moving dipole.
NASA Astrophysics Data System (ADS)
Guo, Haotian; Duan, Fajie; Zhang, Jilong
2016-01-01
Blade tip-timing is the most effective method for blade vibration online measurement of turbomachinery. In this article a synchronous resonance vibration measurement method of blade based on tip-timing is presented. This method requires no once-per revolution sensor which makes it more generally applicable in the condition where this sensor is difficult to install, especially for the high-pressure rotors of dual-rotor engines. Only three casing mounted probes are required to identify the engine order, amplitude, natural frequency and the damping coefficient of the blade. A method is developed to identify the blade which a tip-timing data belongs to without once-per revolution sensor. Theoretical analyses of resonance parameter measurement are presented. Theoretic error of the method is investigated and corrected. Experiments are conducted and the results indicate that blade resonance parameter identification is achieved without once-per revolution sensor.
A plasmonic dipole optical antenna coupled quantum dot infrared photodetector
NASA Astrophysics Data System (ADS)
Mojaverian, Neda; Gu, Guiru; Lu, Xuejun
2015-12-01
In this paper, we report a full-wavelength plasmonic dipole optical antenna coupled quantum dot infrared photodetector (QDIP). The plasmonic dipole optical antenna can effectively modify the EM wave distribution and convert free-space propagation infrared light to localized surface plasmonic resonance (SPR) within the nanometer (nm) gap region of the full-wavelength dipole antenna. The plasmonic dipole optical antenna coupled QDIP shows incident-angle-dependent photocurrent enhancement. The angular dependence follows the far-field pattern of a full-wavelength dipole antenna. The directivity of the plasmonic dipole optical antenna is measured to be 1.8 dB, which agrees well with the antenna simulation. To our best knowledge, this is the first report of the antenna far-field and directivity measurement. The agreement of the detection pattern and the directivity with antenna theory confirms functions of an optical antenna are similar to that of a RF antenna.
Free induction decay caused by a dipole field
NASA Astrophysics Data System (ADS)
Ziener, C. H.; Kurz, F. T.; Kampf, T.
2015-03-01
We analyze the free induction decay of nuclear spins under the influence of restricted diffusion in a magnetic dipole field around cylindrical objects. In contrast to previous publications no restrictions or simplifications concerning the diffusion process are made. By directly solving the Bloch-Torrey equation, analytical expressions for the magnetization are given in terms of an eigenfunction expansion. The field strength-dependent complex nature of the eigenvalue spectrum significantly influences the shape of the free induction decay. As the dipole field is the lowest order of the multipole expansion, the obtained results are important for understanding fundamental mechanisms of spin dephasing in many other applied fields of nuclear magnetic resonance such as biophysics or material science. The analytical methods are applied to interpret the spin dephasing in the free induction decay in cardiac muscle and skeletal muscle. A simple expression for the relevant transverse relaxation time is found in terms of the underlying microscopic parameters of the muscle tissue. The analytical results are in agreement with experimental data. These findings are important for the correct interpretation of magnetic resonance images for clinical diagnosis at all magnetic field strengths and therapy of cardiovascular diseases.
NASA Astrophysics Data System (ADS)
Ahmadinejad, Neda; Tari, Mostafa Talebi
2017-04-01
A density functional theory (DFT) calculations using B3LYP/6-311++G( d,p) method were carried out to investigate the relative stability of the molecules of β-carboline derivatives such as harmaline, harmine, harmalol, harmane and norharmane. Calculated nuclear quadrupole resonance (NQR) parameters were used to determine the 14N nuclear quadrupole coupling constant χ, asymmetry parameter η and EFG tensor ( q zz ). For better understanding of the electronic structure of β-carboline derivatives, natural bond orbital (NBO) analysis, isotropic and anisotropic NMR chemical shieldings were calculated for 14N nuclei using GIAO method for the optimized structures. The NBO analysis shows that pyrrole ring nitrogen (N9) atom has greater tendency than pyridine ring nitrogen (N2) atom to participate in resonance interactions and aromaticity development in the all of these structures. The NMR and NQR parameters were studied in order to find the correlations between electronic structure and the structural stability of the studied molecules.
Derrien, Herve; Leal, Luiz C; Larson, Nancy M; Guber, Klaus H; Wiarda, Dorothea; Arbanas, Goran
2008-01-01
High-resolution neutron capture cross section measurements of 55Mn were recently performed at GELINA by Schillebeeckx et al. (2005) and at ORELA by Guber et al. (2007). The analysis of the experimental data was performed with the computer code SAMMY using the Bayesian approach in the resonance parameters representation of the cross sections. The neutron transmission data taken in 1988 by Harvey et al. (2007) and not analyzed before were added to the SAMMY experimental data base. More than 95% of the s-wave resonances and more than 85% of the p-wave resonances were identified in the energy range up to 125 keV, leading to the neutron strength functions S0 = (3.90 0.78) x 10-4 and S1 = (0.45 0.08) x 10-4. About 25% of the d-wave resonances were identified with a possible strength function of S2 = 1.0 x 10-4. The capture cross section calculated at 0.0253 eV is 13.27 b, and the capture resonance integral is 13.52 0.30 b. In the energy range 15 to 120 keV, the average capture cross section is 12% lower than Lerigoleur value and 25% smaller than Macklin value. GELINA and ORELA experimental capture cross sections show a background cross section not described by the Reich-Moore resonance parameters. Part of this background could be due to a direct capture component and/or to the missing d-wave resonances. The uncertainty of 10% on the average capture cross section above 20 keV is mainly due to the inaccuracy in the calculation of the background components.
Olson, Peter; Amit, Hagay
2006-11-01
The dipole moment of Earth's magnetic field has decreased by nearly 9% over the past 150 years and by about 30% over the past 2,000 years according to archeomagnetic measurements. Here, we explore the causes and the implications of this rapid change. Maps of the geomagnetic field on the core-mantle boundary derived from ground-based and satellite measurements reveal that most of the present episode of dipole moment decrease originates in the southern hemisphere. Weakening and equatorward advection of normal polarity magnetic field by the core flow, combined with proliferation and growth of regions where the magnetic polarity is reversed, are reducing the dipole moment on the core-mantle boundary. Growth of these reversed flux regions has occurred over the past century or longer and is associated with the expansion of the South Atlantic Anomaly, a low-intensity region in the geomagnetic field that presents a radiation hazard at satellite altitudes. We address the speculation that the present episode of dipole moment decrease is a precursor to the next geomagnetic polarity reversal. The paleomagnetic record contains a broad spectrum of dipole moment fluctuations with polarity reversals typically occurring during dipole moment lows. However, the dipole moment is stronger today than its long time average, indicating that polarity reversal is not likely unless the current episode of moment decrease continues for a thousand years or more.
Direct summation of dipole-dipole interactions using the Wolf formalism.
Stenqvist, Björn; Trulsson, Martin; Abrikosov, Alexei I; Lund, Mikael
2015-07-07
We present an expanded Wolf formalism for direct summation of long-range dipole-dipole interactions and rule-of-thumbs how to choose optimal spherical cutoff (Rc) and damping parameter (α). This is done by comparing liquid radial distribution functions, dipole-dipole orientation correlations, particle energies, and dielectric constants, with Ewald sums and the Reaction field method. The resulting rule states that ασ < 1 and αRc > 3 for reduced densities around ρ(∗) = 1 where σ is the particle size. Being a pair potential, the presented approach scales linearly with system size and is applicable to simulations involving point dipoles such as the Stockmayer fluid and polarizable water models.
NASA Astrophysics Data System (ADS)
Kozakiewicz, Joanna; Kulak, Andrzej; Mlynarczyk, Janusz
2015-11-01
Two electrically conductive planetary spheres, the ionosphere and the ground, form a spherical waveguide. Within such a planetary cavity a phenomenon called Schumann resonance (SR) can occur. It is a resonance of extremely low frequency (ELF) electromagnetic waves. The resonance parameters are strongly related to the electromagnetic properties of the cavity. On Mars, as there is no liquid water at the planetary surface, the ground has a low conductivity. In such a situation, ELF waves penetrate into the planetary subsurface up to many kilometers depth. To examine the influence of low-conductivity grounds on ELF propagation, we have introduced a recently developed analytical method, which enables to estimate the propagation parameters and explicate their dependence of the ground properties. Since the presented model is fully analytical, it is computationally efficient and can be very useful in finding inverse solutions. To demonstrate the potential of the method, we present the relationship between individual ground properties and the parameters of Schumann resonance. The obtained results indicate that Martian exploration performed by one ELF station located at the planetary surface can reveal, along with the properties of the ionosphere, the existence of liquid water under the Martian surface.
Nuclear magnetic resonance parameters of atomic xenon dissolved in Gay-Berne model liquid crystal.
Lintuvuori, Juho; Straka, Michal; Vaara, Juha
2007-03-01
We present constant-pressure Monte Carlo simulations of nuclear magnetic resonance (NMR) spectral parameters, nuclear magnetic shielding relative to the free atom as well as nuclear quadrupole coupling, for atomic xenon dissolved in a model thermotropic liquid crystal. The solvent is described by Gay-Berne (GB) molecules with parametrization kappa=4.4, kappa{'}=20.0 , and mu=nu=1 . The reduced pressure of P{*}=2.0 is used. Previous simulations of a pure GB system with this parametrization have shown that upon lowering the temperature, the model exhibits isotropic, nematic, smectic- A , and smectic- B /molecular crystal phases. We introduce spherical xenon solutes and adjust the energy and length scales of the GB-Xe interaction to those of the GB-GB interaction. This is done through first principles quantum chemical calculations carried out for a dimer of model mesogens as well as the mesogen-xenon complex. We preparametrize quantum chemically the Xe nuclear shielding and quadrupole coupling tensors when interacting with the model mesogen, and use the parametrization in a pairwise additive fashion in the analysis of the simulation. We present the temperature evolution of {129/131}Xe shielding and 131Xe quadrupole coupling in the different phases of the GB model. From the simulations, separate isotropic and anisotropic contributions to the experimentally available total shielding can be obtained. At the experimentally relevant concentration, the presence of the xenon atoms does not significantly affect the phase behavior as compared to the pure GB model. The simulations reproduce many of the characteristic experimental features of Xe NMR in real thermotropic LCs: Discontinuity in the value or trends of the shielding and quadrupole coupling at the nematic-isotropic and smectic-A-nematic phase transitions, nonlinear shift evolution in the nematic phase reflecting the behavior of the orientational order parameter, and decreasing shift in the smectic-A phase. The last
ERIC Educational Resources Information Center
Olson, Joel A.; Nordell, Karen J.; Chesnik, Marla A.; Landis, Clark R.; Ellis, Arthur B.; Rzchowski, M. S.; Condren, S. Michael; Lisensky, George C.
2000-01-01
Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)
ERIC Educational Resources Information Center
Olson, Joel A.; Nordell, Karen J.; Chesnik, Marla A.; Landis, Clark R.; Ellis, Arthur B.; Rzchowski, M. S.; Condren, S. Michael; Lisensky, George C.
2000-01-01
Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)
Efficient treatment of induced dipoles
Simmonett, Andrew C.; Pickard, Frank C.; Shao, Yihan; Cheatham, Thomas E.; Brooks, Bernard R.
2015-01-01
Most existing treatments of induced dipoles in polarizable molecular mechanics force field calculations use either the self-consistent variational method, which is solved iteratively, or the “direct” approximation that is non-iterative as a result of neglecting coupling between induced dipoles. The variational method is usually implemented using assumptions that are only strictly valid under tight convergence of the induced dipoles, which can be computationally demanding to enforce. In this work, we discuss the nature of the errors that result from insufficient convergence and suggest a strategy that avoids such problems. Using perturbation theory to reintroduce the mutual coupling into the direct algorithm, we present a computationally efficient method that combines the precision of the direct approach with the accuracy of the variational approach. By analyzing the convergence of this perturbation series, we derive a simple extrapolation formula that delivers a very accurate approximation to the infinite order solution at the cost of only a few iterations. We refer to the new method as extrapolated perturbation theory. Finally, we draw connections to our previously published permanent multipole algorithm to develop an efficient implementation of the electric field and Thole terms and also derive some necessary, but not sufficient, criteria that force field parameters must obey. PMID:26298123
Ennis, J.F.
1984-01-01
While cluster models have had by far their greatest use, apart from natural radioactivity, in light nuclei in the region from YBe to UCa, Iachello and Jackson recently suggested that even in heavy nuclei, just above closed shells, four valence nucleons could form a valence alpha particle cluster orbiting the remaining core. In heavy nuclei, as opposed to light, reflecting the neutron excess (N > Z), such cluster separation results in a separation of the centers of charge and mass and thus generate a static electric dipole moment. The author has undertaken a detailed experimental study of this question using a wide range of techniques and focussing upon the S YRa nucleus. Using a SYPb target and a TC beam at Yale and the reverse reaction at GSI, the author has identified the quadrupole and dipole band members in the level spectrum of this nucleus. From measurements of the absolute lifetimes of many states ranging up to that having J = 15h, the author has shown that the electromagnetic deexcitation matrix elements are indeed enhanced and that they exhaust as much as 15% of molecular sum rule appropriate for these cluster configurations. Having measured many of the pertinent parameters, the author has shown that the Iachello-Jackson dipole model can reproduce what the author has found in S YRa. The new data also provides a stringent test of the spectrum generating algebraic and other approaches to this understanding.
Laboratory Dipole Plasma Physics
NASA Astrophysics Data System (ADS)
Kesner, Jay
2011-10-01
Modern laboratory studies of plasma confined by a strong dipole magnet originated twenty years ago when it was learned that planetary magnetospheres have centrally-peaked plasma pressure profiles that form naturally when solar wind drives plasma circulation and heating. Unlike other internal rings devices, like spherators and octupoles, the magnetic flux tubes of the dipole field expand rapidly with radius. Unlike plasma confinement devices that obtain stability from magnetic shear and average good curvature, like tokamaks and levitrons, the dipole-confined plasma obtains stability from plasma compressibility. These two geometric characteristics of the dipole field have profound consequences: (i) plasma can be stable with local beta exceeding unity, (ii) fluctuations can drive either heat or particles inward to create stationary profiles that are strongly peaked, and (iii) the confinement of particles and energy can decouple. During the past decade, several laboratory dipole experiments and modeling efforts have lead to new understanding of interchange, centrifugal and entropy modes, nonlinear gyrokinetics, and plasma transport. Two devices, the LDX experiment at MIT and RT-1 at the University of Tokyo, operate with levitated superconducting dipole magnets. With a levitated dipole, not only is very high-beta plasma confined in steady state but, also, levitation produces high-temperature at low input power and demonstrates that toroidal magnetic confinement of plasma does not require a toroidal field. Modeling has explained many of the processes operative in these experiments, including the observation of a strong inward particle pinch. Turbulent low-frequency fluctuations in dipole confined plasma cause adiabatic transport and form a fundamental linkage between the radial variation of flux-tube volume and the centrally peaked density and pressure profiles. In collaboration with M.E. Mauel and D.T. Garnier; supported by DoE FG02-98ER54458.
Thermodynamics of systems of aligned dipoles
NASA Astrophysics Data System (ADS)
Daily, K. M.; Blume, D.
2013-05-01
The high-temperature thermodynamics of two-component Fermi gases with interspecies s-wave scattering length is well described by the virial equation of state. This work determines the virial equation of state of weakly-interacting dipolar Bose and Fermi gases under external spherically symmetric confinement. The second-order virial coefficients for two identical dipolar bosons, two identical dipolar fermions and two distinguishable dipoles are calculated from the trap energy spectra. Away from resonance, we employ the Born approximation and find that the virial coefficient for two identical fermions depends quadratically on the dipole length. This suggests that dipolar effects are suppressed in the high temperature limit. Fine tuning the scattering properties of two identical fermions, we identify conditions in which the second-order virial coefficient depends linearly on the dipole length. Analytical expressions are derived and corroborated by numerical calculations. We acknowledge support from the NSF.
Rost, Christian; Rost, Marie-Charlotte; Breithardt, Ole A; Schmid, Michael; Klinghammer, Lutz; Stumpf, Christian; Daniel, Werner G; Flachskampf, Frank A
2014-07-01
Identification of viable but dysfunctional myocardium after myocardial infarction is important for management, including the decision for revascularization. Assessment of infarct transmurality (TRM) by late contrast enhancement on magnetic resonance imaging (MRI) is frequently used for this task but has several limitations, particularly its availability. The goal of this study was to compare the value of several simple echocardiographic parameters measured at rest at the bedside for the identification of three degrees of infarct TRM, with contrast-enhanced MRI as the gold standard. In a prospective, single-center study, 41 patients (33 men; mean age, 62 ± 10 years; 32 with ST-segment elevation infarctions) underwent resting echocardiography and contrast-enhanced MRI <5 days after infarction. Wall motion score, preejection velocity by tissue Doppler, and longitudinal, circumferential, and radial peak systolic strain by speckle-tracking-based strain imaging were assessed, and the findings were compared with infarct TRM stratified by contrast-enhanced MRI (no scar, 0% TRM; nontransmural scar, 1%-50% TRM; and transmural scar, 51%-100% TRM). Four hundred segments showed no scar, 125 showed nontransmural scar, and 213 showed transmural scar on contrast-enhanced MRI. The sensitivity and specificity of visual wall motion scoring to detect any scar versus no scar were 71% and 81%, respectively, similar to values for circumferential strain (sensitivity and specificity both 81% with a cutoff of -14.5%). Longitudinal and radial strain performed less well, and the presence of preejection velocity performed distinctly worse (45% and 90%, respectively). The sensitivity and specificity for identifying nontransmural versus transmural infarction was better for circumferential strain (78% and 75%, respectively, with a cutoff of -10.5%) than for the other strain types, preejection velocity (52% and 67%, respectively), or visual wall motion scoring (50% and 81%, respectively, for a
Marsman, A.; Horbatsch, M.
2011-09-15
Previous work [E. Ackad and M. Horbatsch, Phys. Rev. A 78, 062711 (2008)] on supercritical Dirac resonance parameters from extrapolated analytic continuation, obtained with a Fourier grid method, is generalized by numerically solving the coupled Dirac radial equations to a high precision. The equations, which contain the multipole decomposition of the two-center potential, are augmented by a complex absorbing potential and truncated at various orders in the partial wave expansion to demonstrate convergence of the resonance parameters in the limit of vanishing absorber. The convergence of the partial-wave spinor and of the multipole potential expansions is demonstrated in the supercritical regime. The comparison of critical distances with literature values shows that the work provides benchmark results for future two-center calculations without multipole expansion.
Cho, Herman
2016-02-28
Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.
NASA Astrophysics Data System (ADS)
Cho, Herman
2016-09-01
Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3 / 2 , 5 / 2 , 7 / 2, and 9 / 2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed.
NASA Astrophysics Data System (ADS)
Moaienla, T.; Singh, Th. David; Singh, N. Rajmuhon; Devi, M. Indira
2009-10-01
Studying the absorption difference and comparative absorption spectra of the interaction of Pr(III) and Nd(III) with L-phenylalanine, L-glycine, L-alanine and L-aspartic acid in the presence and absence of Ca 2+ in organic solvents, various energy interaction parameters like Slater-Condon ( FK), Racah ( Ek), Lande factor ( ξ4f), nephelauxetic ratio ( β), bonding ( b1/2), percentage-covalency ( δ) have been evaluated applying partial and multiple regression analysis. The values of oscillator strength ( P) and Judd-Ofelt electric dipole intensity parameter Tλ ( λ = 2, 4, 6) for different 4f-4f transitions have been computed. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength ( P) and Tλ values reveal the mode of binding with different ligands.
Li, Li; Qin, Lei; Wang, Li-Kun; Wan, Yuan-Yuan; Sun, Bai-Sheng
2008-05-01
The 1-3-2 composite is made of 1-3 composite and ceramic base. Its effective properties are calculated based on the linear piezoelectric theory and uniform field theory. The influence of piezoelectric phase volume fraction and composite aspect (thickness/width) on resonance characteristic of square 1-3-2 piezoelectric composite plate has been researched. In addition, some 1-3-2 composite samples were fabricated by dice-fill technology. The resonance frequency of samples was investigated. The results show that the experiment agrees well with the calculation. The pure thickness resonance mode of 1-3-2 composite will be gained when the volume fraction of ceramic bottom is less than 30%; that of ceramic rods is in the range of 30 approximately 80% and the ratio of thickness to width is less than 0.35.
NASA Astrophysics Data System (ADS)
Nori, Franco
2014-03-01
We study a heterostructure which consists of a topological insulator and a superconductor with a hole. This system supports a robust Majorana fermion state bound to the vortex core. We study the possibility of using scanning tunneling spectroscopy (i) to detect the Majorana fermion in this setup and (ii) to study excited states bound to the vortex core. The Majorana fermion manifests itself as an H-dependent zero-bias anomaly of the tunneling conductance. The excited states spectrum differs from the spectrum of a typical Abrikosov vortex, providing additional indirect confirmation of the Majorana state observation. We also study how to manipulate and probe Majorana fermions using super-conducting circuits. In we consider a semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC), which can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, i.e., electric-dipole spin resonance. We develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength ηopt = √ 2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. FN is partly supported by the RIKEN CEMS, iTHES Project, MURI Center for Dynamic Magneto-Optics, JSPS-RFBR Contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program.
NASA Astrophysics Data System (ADS)
Bacon, Allan Mclain
1995-01-01
Optical dipole fluctuations in atoms play an important role in diverse physical phenomena: they limit the signal to background ratio in spectroscopic measurements, and thus limit the accuracy of atomic clocks; they determine the minimum temperature that can be obtained in laser cooling and in optical traps; and, they place a limit on squeezed state experiments. Although there have been many theoretical and experimental studies of noise in radiating atomic systems, the previous work has not provided a complete physical picture of the distinct sources of optical dipole noise. Hence, a detailed study of optical dipole fluctuations in a simple radiating system is of fundamental and pedagogical value. This dissertation presents measurements of optical dipole noise in a particularly simple system consisting of long-lived, coherently driven two-level atoms in an atomic beam. We use atoms with a long radiative lifetime, because the small spontaneous emission rate permits analysis of the noise spectra in terms of a simple fluctuating Bloch vector picture, without decay. The observed noise spectra exhibit manifestly different structure for radiation which is in-phase or out-of-phase with the driving field. The spectra and corresponding analysis afford clear insights into the roles played by three distinct sources of atomic noise: Spontaneous emission, phase-dependent Bloch vector projection noise, and phase-dependent mean dipole Poisson noise. Spontaneous emission and phase-dependent Bloch vector projection noise arise from quantum fluctuations in the optical dipole moment of single atoms. Phase-dependent mean dipole Poisson noise arises from fluctuations in the number of radiating atoms. Two novel experimental techniques permit sensitive measurement of optical dipole noise. First, the signals from two identically prepared experimental regions are subtracted. This method cancels the excess noise in the measured quadrature signal in addition to canceling the excess noise in
RHIC AC DIPOLE DESIGN AND CONSTRUCTION.
BAI,M.; METH,M.; PAI,C.; PARKER,B.; PEGGS,S.; ROSER,T.; SANDERS,R.; TRBOJEVIC,D.; ZALTSMAN,A.
2001-06-18
Two ac dipoles with vertical and horizontal magnetic field have been proposed at RHIC for applications in linear and non-linear beam dynamics and spin manipulations. A magnetic field amplitude of 380 Gm is required to produce a coherent oscillation of 5 times the rms beam size at the top energy. We take the ac dipole frequency to be 1.0% of the revolution frequency away from the betatron frequency. To achieve the strong magnetic field with minimum power loss, an air-core magnet with two seven turn winding of low loss Litz wire resonating at 64 kHz is designed. The system is also designed to allow one to connect the two magnet winding in series to resonate at 37 kHz for the spin manipulation. Measurements of a half length prototype magnet are also presented.
Spin Resonance Strength Calculations
NASA Astrophysics Data System (ADS)
Courant, E. D.
2009-08-01
In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.
Pygmy dipole response in 238U nucleus
NASA Astrophysics Data System (ADS)
Guliyev, Ekber; Kuliev, Ali Akbar; Quliyev, Huseynqulu
2017-02-01
The presence of the El pygmy dipole resonance (PDR) in the actinide nucleus 238U was shown via QRPA. Below the particle threshold energy, 24 excitation states were calculated. The calculations, is demonstrating the presence of a PDR with evidence for K splitting. The calculations further suggest that the PDR in 238U is predominantly K=0. The obtained results show universality of the PDR in atomic nuclei.
Probing the Lipid Membrane Dipole Potential by Atomic Force Microscopy
Yang, Yi; Mayer, Kathryn M.; Wickremasinghe, Nissanka S.; Hafner, Jason H.
2008-01-01
The electrostatic properties of biological membranes can be described by three parameters: the transmembrane potential, the membrane surface potential, and the membrane dipole potential. The first two are well characterized in terms of their magnitudes and biological effects. The dipole potential, however, is not well characterized. Various methods to measure the membrane dipole potential indirectly yield different values, and there is not even agreement on the source of the membrane dipole moment. This ambiguity impedes investigations into the biological effects of the membrane dipole moment, which should be substantial considering the large interfacial fields with which it is associated. Electrostatic analysis of phosphatidylcholine lipid membranes with the atomic force microscope reveals a repulsive force between the negatively charged probe tips and the zwitterionic lipids. This unexpected interaction has been analyzed quantitatively to reveal that the repulsion is due to a weak external field created by the internal membrane dipole potential. The analysis yields a dipole moment of 1.5 Debye per lipid with a dipole potential of +275 mV for supported phosphatidylcholine membranes. This new ability to quantitatively measure the membrane dipole moment in a noninvasive manner with nanometer scale spatial resolution will be useful in identifying the biological effects of the dipole potential. PMID:18805919
Coherent synchro-betatron resonance
Burov, A.; Lebedev, V.; /Fermilab
2006-12-01
Coherent synchro-betatron resonances can present a serious limit for low-energy synchrotrons with strong space charge. Here, an excitation of a dipole transverse mode is considered at resonance condition.
Lai, Zhi-Hui; Leng, Yong-Gang
2015-01-01
A two-dimensional Duffing oscillator which can produce stochastic resonance (SR) is studied in this paper. We introduce its SR mechanism and present a generalized parameter-adjusted SR (GPASR) model of this oscillator for the necessity of parameter adjustments. The Kramers rate is chosen as the theoretical basis to establish a judgmental function for judging the occurrence of SR in this model; and to analyze and summarize the parameter-adjusted rules under unmatched signal amplitude, frequency, and/or noise-intensity. Furthermore, we propose the weak-signal detection approach based on this GPASR model. Finally, we employ two practical examples to demonstrate the feasibility of the proposed approach in practical engineering application. PMID:26343671
Lai, Zhi-Hui; Leng, Yong-Gang
2015-08-28
A two-dimensional Duffing oscillator which can produce stochastic resonance (SR) is studied in this paper. We introduce its SR mechanism and present a generalized parameter-adjusted SR (GPASR) model of this oscillator for the necessity of parameter adjustments. The Kramers rate is chosen as the theoretical basis to establish a judgmental function for judging the occurrence of SR in this model; and to analyze and summarize the parameter-adjusted rules under unmatched signal amplitude, frequency, and/or noise-intensity. Furthermore, we propose the weak-signal detection approach based on this GPASR model. Finally, we employ two practical examples to demonstrate the feasibility of the proposed approach in practical engineering application.
Polar and low polar solvents media effect on dipole moments of some diazo Sudan dyes.
Zakerhamidi, M S; Golghasemi Sorkhabi, Sh; Shamkhali, A N
2014-06-05
Absorption and fluorescence spectra of three Sudan dyes (SudanIII, SudanIV and Sudan black B) were recorded in various solvents with different polarity in the range of 300-800nm, at room temperature. The solvatochromic method was used to investigate dipole moments of these dyes in ground and excited states, in different media. The solvatochromic behavior of these substances and their solvent-solute interactions were analyzed via solvent polarity parameters. Obtained results express the effects of solvation on tautomerism and molecular configuration (geometry) of Sudan dyes in solvent media with different polarity. Furthermore, analyze of solvent-solute interactions and value of ground and excited states dipole moments suggests different forms of resonance structures for Sudan dyes in polar and low-polar solvents.
Stable collective dynamics of two-level systems coupled by dipole interactions
NASA Astrophysics Data System (ADS)
Parmee, C. D.; Cooper, N. R.
2017-03-01
We study the dynamics of a set of two-level systems coupled by dipolar interactions under a resonant external Rabi drive. The two-level systems are prepared initially in a coherent product state, and we ask how the nonequilibrium conditions caused by the drive affect this coherence. We study the full nonlinear dynamics of the coupled two-level systems within a classical approximation by analyzing numerically the equations of motion and determining the stability of the collective coherent state within classical Floquet theory. We establish the behavior analytically in the high Rabi coupling limit by employing a Magnus expansion and spin-wave analysis. Our results show that, typically, the dipole interactions between the two-level systems lead to instabilities that cause a breakdown of the collective Rabi oscillations. However, we identify parameter regimes for which the two-level systems undergo collective coherent Rabi oscillations even in the presence of the dipole interactions.
Magnetic Dipole Scattering from Metallic Nanowire for Ultrasensitive Deflection Sensing
NASA Astrophysics Data System (ADS)
Xi, Zheng; Urbach, H. P.
2017-08-01
It is generally believed that when a single metallic nanowire is sufficiently small, it scatters like a point electric dipole. We show theoretically when a metallic nanowire is placed inside specially designed beams, the magnetic dipole contribution along with the electric dipole resonance can lead to unidirectional scattering in the far field, fulfilling Kerker's condition. Remarkably, this far-field unidirectional scattering encodes information that is highly dependent on the nanowire's deflection at a scale much smaller than the wavelength. The special roles of small but essential magnetic response along with the plasmonic resonance are highlighted for this extreme sensitivity as compared with the dielectric counterpart. In addition, the same essential role of the magnetic dipole contribution is also presented for a very small metallic nanosphere.
NASA Astrophysics Data System (ADS)
Fan, C.; Tian, Y.; Wang, Z. Q.; Nie, J. K.; Wang, G. K.; Liu, X. S.
2017-06-01
In view of the noise feature and service environment of urban power substations, this paper explores the idea of compound impedance, fills some porous sound-absorption material in the first resonance cavity of the double-resonance sound-absorption material, and designs a new-type of composite acoustic board. We conduct some acoustic characterizations according to the standard test of impedance tube, and research on the influence of assembly order, the thickness and area density of the filling material, and back cavity on material sound-absorption performance. The results show that the new-type of acoustic board consisting of aluminum fibrous material as inner structure, micro-porous board as outer structure, and polyester-filled space between them, has good sound-absorption performance for low frequency and full frequency noise. When the thickness, area density of filling material and thickness of back cavity increase, the sound absorption coefficient curve peak will move toward low frequency.
NASA Astrophysics Data System (ADS)
Panahi, M.; Solookinejad, G.; Ahmadi Sangachin, E.; Hossein Asadpour, Seyyed
2016-07-01
The impact of the dipole-dipole interaction on the Goo-Hänchen (GH) shifts in reflected and transmitted lights is investigated. A weak probe beam is incident on a cavity containing the donor and acceptor quantum dots embedded in a nonlinear photonic crystal. We deduced that the GH shifts can be easily adjusted via controlling the corresponding parameters of the system in the presence or absence of dipole-dipole interaction. Our proposed model may be useful to developing the all-optical devices based on photonic materials doped with nanoparticles.
Design parameters of a resonant infrared photoconductor with unity quantum efficiency
NASA Technical Reports Server (NTRS)
Farhoomand, Jam; Mcmurray, Robert E., Jr.
1991-01-01
This paper proposes a concept of a resonant infrared photoconductor that has characteristics of 100 percent quantum efficiency, high photoconductive gain, and very low noise equivalent power. Central to this concept is an establishment of a high-finesse absorption cavity internal to the detector element. A theoretical analysis is carried out, demonstrating this concept and providing some design guidelines. A Ge:Ga FIR detector is presently being fabricated using this approach.
Design parameters of a resonant infrared photoconductor with unity quantum efficiency
NASA Technical Reports Server (NTRS)
Farhoomand, Jam; Mcmurray, Robert E., Jr.
1991-01-01
This paper proposes a concept of a resonant infrared photoconductor that has characteristics of 100 percent quantum efficiency, high photoconductive gain, and very low noise equivalent power. Central to this concept is an establishment of a high-finesse absorption cavity internal to the detector element. A theoretical analysis is carried out, demonstrating this concept and providing some design guidelines. A Ge:Ga FIR detector is presently being fabricated using this approach.
Approximate Schumann resonance parameters for a two-scale-height ionosphere
NASA Technical Reports Server (NTRS)
Sentman, D. D.
1990-01-01
An isotropic, spherically symmetric two-scale-height ionosphere's transverse magnetic mode eigenfrequencies, as well as the height and angular profiles of its electric and magnetic fields, are presently addressed by an approximate solution. The electromagnetic energy in the eigenmodes is equally partitioned between the electric and magnetic fields, allowing a simple expression of the relative degrees of dissipation within the radial and tangential dissipation layers. The results obtained may be relevant to interpretations of the temporal variations in the Schumann resonances.
Mechanical design parameters for detection of nuclear signals by magnetic resonance force microscopy
Moore, G.J.; Hanlon, J.A.; Lamartine, B.; Hawley, M.; Solem, J.C.; Signer, S.; Jarmer, J.J.; Penttila, S.; Sillerud, L.O.; Pryputniewicz, R.J.
1993-10-01
Recent theoretical work has shown that mechanical detection of magnetic resonance from a single nuclear spin is in principle possible. This theory has recently been experimentally validated by the mechanical detection of electron spin resonance signals using microscale cantilevers. Currently we are extending this technology in an attempt to detect nuclear signals which are extending this technology in an attempt to detect nuclear signals which are three orders of magnitude lower in intensity than electron signals. In order to achieve the needed thousand-fold improvement in sensitivity we have undertaken the development of optimized mechanical cantilevers and highly polarized samples. Finite element modeling is used as a tool to simulate cantilever beam dynamics and to optimize the mechanical properties including Q, resonant frequency, amplitude of vibration and spring constant. Simulations are compared to experiments using heterodyne hologram interferometry. Nanofabrication of optimized cantilevers via ion milling will be directed by the outcome of these simulations and experiments. Highly polarized samples are developed using a three-fold approach: (1) high magnetic field strength (2.5T), (2) low temperature (1K), and (3) use of samples polarized by dynamic nuclear polarization. Our recent experiments have demonstrated nuclear polarizations in excess of 50% in molecules of toulene.
Measurements of ground motion and SSC dipole vibrations
Parkhomchuk, V.V.; Shiltsev, V.D.; Weaver, H.J.
1993-06-01
The results of seismic ground measurements at the Superconducting Super Collider (SSC) site and investigations of vibrational properties of superconducting dipoles for the SSC are presented. Spectral analysis of the data obtained in the large frequency band from 0.05 Hz to 2000 Hz is done. Resonant behavior and the dipole-to-ground transform ratio are investigated. The influence of measured vibrations on SSC operations is considered.
Musselman, Catherine; Zhang, Qi; Al-Hashimi, Hashim; Andricioaei, Ioan
2010-01-21
Nuclear magnetic resonance (NMR) spectroscopy and molecular dynamics (MD) simulations are both techniques that can be used to characterize the structural dynamics of biomolecules and their underlying time scales. Comparison of relaxation parameters obtained through each methodology allows for cross validation of techniques and for complementarity in the analysis of dynamics. Here we present a combined NMR/MD study of the dynamics of HIV-1 transactivation response (TAR) RNA. We compute relaxation constants (R(1), R(2), and NOE) and model-free parameters (S(2) and tau) from a 65 ns molecular dynamics (MD) trajectory and compare them with the respective parameters measured in a domain-elongation NMR experiment. Using the elongated domain as the frame of reference for all computed parameters allows for a direct comparison between experiment and simulation. We see good agreement for many parameters and gain further insight into the nature of the local and global dynamics of TAR, which are found to be quite complex, spanning multiple time scales. For the few cases where agreement is poor, comparison of the dynamical parameters provides insight into the limits of each technique. We suggest a frequency-matching procedure that yields an upper bound for the time scale of dynamics to which the NMR relaxation experiment is sensitive.
Araujo Júnior, Edward; Nakano, Mayra Lemos; Nardozza, Luciano Marcondes Machado; Haratz, Karina Krajden; Oliveira, Patrícia Soares; Martins, Wellington P; Ajzen, Sérgio Aron; Moron, Antonio Fernandes
2013-05-01
To compare two-dimensional ultrasonography (2DUS) and magnetic resonance imaging (MRI) for assessing brain and spine parameters in fetuses with spina bifida. A cross-sectional study was conducted on 15 fetuses with spina bifida (one with encephalocele, four with rachischisis and 10 with myelomeningocele). The size of the atrium of the lateral ventricle, percentage shortening of the cerebellum, degree of compromising of the first vertebra and total number of vertebras affected by herniation were assessed. The MRI examination was performed not more than 7 days after the 2DUS. To compare and correlate the parameters from the two techniques, the paired Student's t test and intraclass correlation coefficient (ICC) were used. To assess the correlations of atrium measurements from 2DUS and MRI with other parameters, Pearson's correlation coefficient (r) was used. No significant difference was observed in any of the means of the parameters assessed using the two techniques (p > 0.05). Both 2DUS and MRI seemed to present satisfactory reliability in measurements on the size of the atrium of the lateral ventricle and the first vertebra affected (ICC = 0.88 and 0.75, respectively). Measurements on the atrium of the lateral ventricle from 2DUS correlated better with the other parameters than did measurements from MRI. In fetuses with spina bifida, 2DUS and MRI present similar results, but measurements on the atrium of the lateral ventricle from 2DUS correlated better with the other parameters.
Yanagisawa, Osamu; Kurihara, Toshiyuki; Kobayashi, Naoyuki; Fukubayashi, Toru
2011-10-01
To assess the effects of strenuous exercise on magnetic resonance diffusion parameters and muscle-tendon complex function in skeletal muscle. Six men performed ankle plantar flexion exercises with eccentric contraction. The fractional anisotropy (FA), λ(1) , λ(2) , λ(3) , mean diffusivity (MD), and T(2) values in the triceps surae muscles were measured by magnetic resonance diffusion tensor and spin-echo imaging. Passive torque of plantar flexors, maximal voluntary isometric plantar flexion torques (MVIP), and Achilles tendon stiffness during MVIP were measured by combined ultrasonography and dynamometry. Plasma creatine kinase and muscle soreness were also assessed. These parameters were measured before and 1-8 days postexercise. The medial gastrocnemius exhibited significantly decreased FA 2-5 days after, increased λ(2) 3 days after, and increased λ(3) 2 and 3 days after exercise. This muscle also showed significantly increased MD and T(2) values 3 days postexercise. MVIP significantly decreased 2 and 3 days postexercise, while passive torque significantly increased 2 days postexercise. Creatine kinase and muscle soreness increased 3-5 days and 1-5 days postexercise, respectively. Exercise-induced muscle damage manifested as significant changes in muscle diffusion parameters with muscle-tendon complex dysfunction and delayed-onset muscle soreness. Copyright © 2011 Wiley-Liss, Inc.
Experiments with Dipole Antennas
ERIC Educational Resources Information Center
Kraftmakher, Yaakov
2009-01-01
Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…
Kartashov, Yaroslav V; Ferrando, Albert; García-March, Miguel-Angel
2007-08-01
On universal symmetry grounds, we analyze the existence of a new type of discrete-symmetry vortex solitons that can be considered as coherent states of dipole solitons carrying a nonzero topological charge. Remarkably, they can be also interpreted as excited angular Bloch states. The stability of new soliton states is elucidated numerically.
Experiments with Dipole Antennas
ERIC Educational Resources Information Center
Kraftmakher, Yaakov
2009-01-01
Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…
The viscous modulation of Lamb's dipole vortex
NASA Astrophysics Data System (ADS)
van de Fliert, B. W.
1996-07-01
A description of the adiabatic decay of the Lamb dipolar vortex is motivated by a variational characterization of the dipole. The parameters in the description are the values of the entrophy and linear momentum integrals, which change in time due to the dissipation. It is observed that the dipole dilates during the decay process [radius R˜(νt)1/2], while the amplitude of the vortex and its translation speed diminish in time proportional to (νt)-3/2 and (νt)-1.
Geometrical Simplification of the Dipole-Dipole Interaction Formula
ERIC Educational Resources Information Center
Kocbach, Ladislav; Lubbad, Suhail
2010-01-01
Many students meet dipole-dipole potential energy quite early on when they are taught electrostatics or magnetostatics and it is also a very popular formula, featured in encyclopedias. We show that by a simple rewriting of the formula it becomes apparent that, for example, by reorienting the two dipoles, their attraction can become exactly twice…
Geometrical Simplification of the Dipole-Dipole Interaction Formula
ERIC Educational Resources Information Center
Kocbach, Ladislav; Lubbad, Suhail
2010-01-01
Many students meet dipole-dipole potential energy quite early on when they are taught electrostatics or magnetostatics and it is also a very popular formula, featured in encyclopedias. We show that by a simple rewriting of the formula it becomes apparent that, for example, by reorienting the two dipoles, their attraction can become exactly twice…
BEAM MANIPULATION WITH AN RF DIPOLE.
BAI,M.
1999-03-29
Coherent betatron motion adiabatically excited by an RF dipole has been successfully employed to overcome strong intrinsic spin depolarization resonances in the AGS, while a solenoid partial snake has been used to correct imperfection spin resonances. The experimental results showed that a full spin flip was obtained in passing through an intrinsic spin resonance when all the beam particles were forced to oscillate coherently at a large amplitude without diluting the beam emittance. With this method, we have successfully accelerated polarized beam up to 23.5 GeV/c. A new type of second order spin resonances was also discovered. As a non-destructive manipulation, this method can also be used for nonlinear beam dynamics studies and beam diagnosis such as measuring phase advance and betatron amplitude function.
Cho, Herman
2016-09-01
Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2, 5/2, 7/2, and 9/2. These results may be used to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistry program.
An Analysis Method for Superconducting Resonator Parameter Extraction with Complex Baseline Removal
NASA Technical Reports Server (NTRS)
Cataldo, Giuseppe
2014-01-01
A new semi-empirical model is proposed for extracting the quality (Q) factors of arrays of superconducting microwave kinetic inductance detectors (MKIDs). The determination of the total internal and coupling Q factors enables the computation of the loss in the superconducting transmission lines. The method used allows the simultaneous analysis of multiple interacting discrete resonators with the presence of a complex spectral baseline arising from reflections in the system. The baseline removal allows an unbiased estimate of the device response as measured in a cryogenic instrumentation setting.
Biller, Joshua R; Mitchell, Deborah G; Tseytlin, Mark; Elajaili, Hanan; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R
2016-09-26
We demonstrate a superior method of 2D spectral-spatial imaging of stable radical reporter molecules at 250 MHz using rapid-scan electron-paramagnetic-resonance (RS-EPR), which can provide quantitative information under in vivo conditions on oxygen concentration, pH, redox status and concentration of signaling molecules (i.e., OH(•), NO(•)). The RS-EPR technique has a higher sensitivity, improved spatial resolution (1 mm), and shorter acquisition time in comparison to the standard continuous wave (CW) technique. A variety of phantom configurations have been tested, with spatial resolution varying from 1 to 6 mm, and spectral width of the reporter molecules ranging from 16 µT (160 mG) to 5 mT (50 G). A cross-loop bimodal resonator decouples excitation and detection, reducing the noise, while the rapid scan effect allows more power to be input to the spin system before saturation, increasing the EPR signal. This leads to a substantially higher signal-to-noise ratio than in conventional CW EPR experiments.
Chen, Sez-Jade; Sinsuebphon, Nattawut; Intes, Xavier
2015-01-01
Förster Resonance Energy Transfer (FRET) enables the observation of interactions at the nanoscale level through the use of fluorescence optical imaging techniques. In FRET, fluorescence lifetime imaging can be used to quantify the fluorescence lifetime changes of the donor molecule, which are associated with proximity between acceptor and donor molecules. Among the FRET parameters derived from fluorescence lifetime imaging, the percentage of donor that interacts with the acceptor (in proximity) can be estimated via model-based fitting. However, estimation of the lifetime parameters can be affected by the acquisition parameters such as the temporal characteristics of the imaging system. Herein, we investigate the effect of various gate widths on the accuracy of estimation of FRET parameters with focus on the near-infrared spectral window. Experiments were performed in silico, in vitro, and in vivo with gate width sizes ranging from 300 ps to 1000 ps in intervals of 100 ps. For all cases, the FRET parameters were retrieved accurately and the imaging acquisition time was decreased three-fold. These results indicate that increasing the gate width up to 1000 ps still allows for accurate quantification of FRET interactions even in the case of short lifetimes such as those encountered with near-infrared FRET pairs. PMID:26557647
Dipole characterization of single neurons from their extracellular action potentials
Victor, Jonathan D.
2011-01-01
The spatial variation of the extracellular action potentials (EAP) of a single neuron contains information about the size and location of the dominant current source of its action potential generator, which is typically in the vicinity of the soma. Using this dependence in reverse in a three-component realistic probe + brain + source model, we solved the inverse problem of characterizing the equivalent current source of an isolated neuron from the EAP data sampled by an extracellular probe at multiple independent recording locations. We used a dipole for the model source because there is extensive evidence it accurately captures the spatial roll-off of the EAP amplitude, and because, as we show, dipole localization, beyond a minimum cell-probe distance, is a more accurate alternative to approaches based on monopole source models. Dipole characterization is separable into a linear dipole moment optimization where the dipole location is fixed, and a second, nonlinear, global optimization of the source location. We solved the linear optimization on a discrete grid via the lead fields of the probe, which can be calculated for any realistic probe + brain model by the finite element method. The global source location was optimized by means of Tikhonov regularization that jointly minimizes model error and dipole size. The particular strategy chosen reflects the fact that the dipole model is used in the near field, in contrast to the typical prior applications of dipole models to EKG and EEG source analysis. We applied dipole localization to data collected with stepped tetrodes whose detailed geometry was measured via scanning electron microscopy. The optimal dipole could account for 96% of the power in the spatial variation of the EAP amplitude. Among various model error contributions to the residual, we address especially the error in probe geometry, and the extent to which it biases estimates of dipole parameters. This dipole characterization method can be applied to
Konno, Kohkichi Nagasawa, Tomoaki Takahashi, Rohta
2016-12-15
We consider the scattering of a quantum particle by two independent, successive parity-invariant point interactions in one dimension. The parameter space for the two point interactions is given by the direct product of two tori, which is described by four parameters. By investigating the effects of the two point interactions on the transmission probability of plane wave, we obtain the conditions for the parameter space under which perfect resonant transmission occur. The resonance conditions are found to be described by symmetric and anti-symmetric relations between the parameters.
Final Report: Levitated Dipole Experiment
Kesner, Jay; Mauel, Michael
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier et al., Physics of Plasmas, 13 (2006) 056111]. High- beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability made LDX the longest pulse fusion confinement experiment operating in the U.S. fusion program. A significant measure of progress in the LDX research program was the routine investigation of plasma confinement with a magnetically-levitated dipole and the resulting observations of confinement improvement. In both supported and levitated configurations, detailed measurements were made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma was created by multi frequency electron cyclotron resonance heating at 2.45 GHz, 6.4 GHz, 10.5 GHz and 28 GHz allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole was levitated or supported, the peak thermal electron temperature was estimated to exceed 500 eV and peak densities to approach 1e18 m^{-3}. We have found that levitation causes a strong inwards density pinch [Boxer et al., Nature Physics, 6 (2010) 207] and we have observed the central plasma density increase dramatically indicating a significant improvement in the confinement of a thermal plasma species.
Michael, Dada O; Bamidele, Awojoyogbe O; Adewale, Adesola O; Karem, Boubaker
2013-01-01
Nuclear magnetic resonance (NMR) allows for fast, accurate and noninvasive measurement of fluid flow in restricted and non-restricted media. The results of such measurements may be possible for a very small B 0 field and can be enhanced through detailed examination of generating functions that may arise from polynomial solutions of NMR flow equations in terms of Legendre polynomials and Boubaker polynomials. The generating functions of these polynomials can present an array of interesting possibilities that may be useful for understanding the basic physics of extracting relevant NMR flow information from which various hemodynamic problems can be carefully studied. Specifically, these results may be used to develop effective drugs for cardiovascular-related diseases.
NASA Astrophysics Data System (ADS)
Geya, Yuto; Kimura, Takeshi; Fujisaki, Hirotaka; Terada, Yasuhiko; Kose, Katsumi; Haishi, Tomoyuki; Gemma, Hiroshi; Sekozawa, Yoshihiko
2013-01-01
Longitudinal nuclear magnetic resonance (NMR) parameter measurements of Japanese pear fruit (Pyrus pyrifolia Nakai, Kosui) were performed using an electrically mobile magnetic resonance imaging (MRI) system with a 0.2 T and 16 cm gap permanent magnet. To measure the relaxation times and apparent diffusion coefficients of the pear fruit in relation to their weight, seven pear fruits were harvested almost every week during the cell enlargement period and measured in a research orchard. To evaluate the in situ relaxation times, six pear fruits were longitudinally measured for about two months during the same period. The measurements for the harvested samples showed good agreement with the in situ measurements. From the measurements of the harvested samples, it is clear that the relaxation rates of the pear fruits linearly change with the inverse of the linear dimension of the fruits, demonstrating that the relaxation mechanism is a surface relaxation. We therefore conclude that the mobile MRI system is a useful device for measuring the NMR parameters of outdoor living plants.
Reevaluation of 58Ni and 60Ni Resonance Parameters in the Energy Range Thermal to 800 keV
Derrien, Herve; Leal, Luiz C; Guber, Klaus H; Wiarda, Dorothea; Arbanas, Goran
2009-01-01
The previous 58Ni and 60Ni set of resonance parameters (ENDF/B-VII-0, JEFF-3, etc.) was based on the SAMMY analysis of Oak Ridge National Laboratory neutron transmission, scattering cross section and capture cross section measurements by C. M. Perey et al. The present results were obtained by adding to the SAMMY experimental data base the capture cross sections measured recently at the Oak Ridge Linear Electron Accelerator by Guber et al. and the Geel Electron Linear Accelerator very high-resolution neutron transmission measurements performed by Brusegan et al. A complete resonance parameter covariance matrix (RPCM) was obtained from the SAMMY analysis of the experimental database. The data sets were made consistent, when needed, by adjusting the neutron energy scales, the normalization coefficients, and the background corrections. The RPCM allows the calculation of the cross section uncertainties due mainly to statistical errors in the experimental data. The systematic uncertainties of the experimental data, estimated from the preliminary analyses of the experimental database, were taken into account in the cross section covariance matrix (CSCM) for total, scattering, and capture cross sections. The diagonal elements of the CSCM were obtained by quadratic combination of the different components of the uncertainties. Because of a lack of experimental information, the energy correlations were not obtained, and a value of 0.5 was arbitrarily taken for all the CSCM nondiagonal elements.
Diagnostics of the Fermilab Tevatron using an AC dipole
Miyamoto, Ryoichi
2008-08-01
The Fermilab Tevatron is currently the world's highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron's beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f ~ 20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of the beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements.
Giant Primeval Magnetic Dipoles
NASA Astrophysics Data System (ADS)
Thompson, Christopher
2017-07-01
Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.
NASA Astrophysics Data System (ADS)
Holanda, B. A.; Cordeiro, R. C.; Blak, A. R.
2010-11-01
Dipole defects in gamma irradiated and thermally treated beryl (Be3Al2Si6O18) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.
NASA Astrophysics Data System (ADS)
Girwidz, Raimund V.
2016-11-01
The Hertzian dipole is fundamental to the understanding of dipole radiation. It provides basic insights into the genesis of electromagnetic waves and lays the groundwork for an understanding of half-wave antennae and other types. Equations for the electric and magnetic fields of such a dipole can be derived mathematically. However these are very abstract descriptions. Interpreting these equations and understanding travelling electromagnetic waves are highly limited in that sense. Visualizations can be a valuable supplement that vividly present properties of electromagnetic fields and their propagation. The computer simulation presented below provides additional instructive illustrations for university lectures on electrodynamics, broadening the experience well beyond what is possible with abstract equations. This paper refers to a multimedia program for PCs, tablets and smartphones, and introduces and discusses several animated illustrations. Special features of multiple representations and combined illustrations will be used to provide insight into spatial and temporal characteristics of field distributions—which also draw attention to the flow of energy. These visualizations offer additional information, including the relationships between different representations that promote deeper understanding. Finally, some aspects are also illustrated that often remain unclear in lectures.
Ma, Wanling; Li, Na; Zhao, Weiwei; Ren, Jing; Wei, Mengqi; Yang, Yong; Wang, Yingmei; Fu, Xin; Zhang, Zhuoli; Larson, Andrew C; Huan, Yi
2016-01-01
To clarify diffusion and perfusion abnormalities and evaluate correlation between apparent diffusion coefficient (ADC), MR perfusion and histopathologic parameters of pancreatic cancer (PC). Eighteen patients with PC underwent diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Parameters of DCE-MRI and ADC of cancer and non-cancerous tissue were compared. Correlation between the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space (K, volume of the extravascular extracellular space per unit volume of tissue (Ve), and ADC of PC and histopathologic parameters were analyzed. The rate constant that represents transfer of contrast agent from the extravascular extracellular space into blood plasma, K, tissue volume fraction occupied by vascular space, and ADC of PC were significantly lower than nontumoral pancreases. Ve of PC was significantly higher than that of nontumoral pancreas. Apparent diffusion coefficient and K values of PC were negatively correlated to fibrosis content and fibroblast activation protein staining score. Fibrosis content was positively correlated to Ve. Apparent diffusion coefficient values and parameters of DCE-MRI can differentiate PC from nontumoral pancreases. There are correlations between ADC, K, Ve, and fibrosis content of PC. Fibroblast activation protein staining score of PC is negatively correlated to ADC and K. Apparent diffusion coefficient, K, and Ve may be feasible to predict prognosis of PC.
NASA Astrophysics Data System (ADS)
Swanson, R. D.; Binley, A. M.; Keating, K.; France, S.; Osterman, G. K.; Day-Lewis, F. D.; Singha, K.
2013-12-01
The advection-dispersion equation fails to describe non-Fickian solute transport in saturated porous media, necessitating the use of other models. The dual-domain mass transfer (DDMT) model partitions the total porosity into mobile and less-mobile domains with solute exchange between the domains; consequently, the DDMT model can produce a better fit to breakthrough curves (BTCs) in systems defined by more- and less-mobile components. However, direct experimental estimation of DDMT model parameters such as rate of exchange and the mobile and less-mobile porosities remains elusive. Consequently, model parameters are often calculated purely as a model fitting exercise. There is a clear need for material characterization techniques that can offer some insight into the pore space geometrical arrangement, particularly if such techniques can be extended to the field scale. Here, we interpret static direct-current (DC) resistivity, complex resistivity (CR) and nuclear magnetic resonance (NMR) geophysical measurements in the characterization of mass transfer parameters. We use two different samples of the zeolite clinoptilolite, a material shown to demonstrate solute mass transfer due to a significant intragranular porosity, along with glass beads as a control. We explore the relation between geophysical and DDMT parameters in conjunction with supporting material characterization methods. Our results reveal how these geophysical measurements can offer some insight into the pore structures controlling the observed anomalous transport behavior.
Dynamically tuned high-Q AC-dipole implementation
Oddo, P.; Bai, M.; Dawson, W.C.; Meng, W.; Mernick, K.; Pai, C.; Roser, T.; Russo, T.
2010-05-02
AC-dipole magnets are typically implemented as a parallel LC resonant circuit. To maximize efficiency, it's beneficial to operate at a high Q. This, however, limits the magnet to a narrow frequency range. Current designs therefore operate at a low Q to provide a wider bandwidth at the cost of efficiency. Dynamically tuning a high Q resonant circuit tries to maintain a high efficiency while providing a wide frequency range. The results of ongoing efforts at BNL to implement dynamically tuned high-Q AC dipoles will be presented.
Conductor Development for High Field Dipole Magnets
Scanlan, R.M.; Dietderich, D.R.; Higley, H.C.
2000-03-01
Historically, improvements in dipole magnet performance have been paced by improvements in the superconductor available for use in these magnets. The critical conductor performance parameters for dipole magnets include current density, piece length, effective filament size, and cost. Each of these parameters is important for efficient, cost effective dipoles, with critical current density being perhaps the most important. Several promising magnet designs for the next hadron collider or a muon collider require fields of 12 T or higber, i.e. beyond the reach of NbTi. The conductor options include Nb{sub 3}Sn, Nb{sub 3}Al, or the high temperature superconductors. Although these conductors have the potential to provide the combination of performance and cost required, none of them have been developed sufficiently at this point to satisfy all the requirements. This paper will review the status of each class of advanced conductor and discuss the remaining problems that require solutions before these new conductors can be considered as practical. In particular, the plans for a new program to develop Nb{sub 3}Sn and Nb{sub 3}Al conductors for high energy physics applications will be presented. Also, the development of a multikiloamp Bi-2212 cable for dipole magnet applications will be reported.
2007-11-02
DESE : another decimative subspace-based parameter estimation algorithm, recently proposed as Decimative Spectral Estimation [3]. In what follows...Sponsoring/Monitoring Agency Name(s) and Address(es) US Army Research , Development & Standardization Group (UK) PSC 802 Box 15 FPO AE 09499-1500 Sponsor...1DXstackX∗stack. (12) C. DESE This algorithm was presented very recently [3]. Like HTLS, DESE also makes use of the SVD of a Hankel ma- trix and the
NASA Astrophysics Data System (ADS)
Chachaty, Claude; Soulié, Edgar J.
1995-12-01
When measurements on single crystals are not feasible, approximate values of the static spin Hamiltonian parameters are in many cases obtained from the ESR spectra of randomly oriented paramagnetic species. The accuracy of such determinations is considerably improved by optimizing these parameters by means of automated simulation programs resorting to the nonlinear least squares fit of experimental spectra. The principles of the simplex method of Nelder and Mead and of the method of Levenberg-Marquardt, generally used for that purpose, are reported. Examples are given of the applications of the latter, which has the advantage of converging rapidly, to S = 1/2 paramagnetic species in rigid matrices. Optimization procedures based on the Levenberg-Marquardt algorithm, are extended to the determination of dynamic parameters of nitroxide spin-probes, namely their tumbling correlation times in fluid and viscous isotropic media as well as in liquid crystalline phases or their exchange rates between inequivalent sites. Lastly, it is shown on the example of a nitroxide biradical, that similar methods can be applied to the study of the dynamics of multiple conformational changes in a paramagnetic flexible molecule.
Localized spoof surface plasmon resonances at terahertz range
NASA Astrophysics Data System (ADS)
Chen, Lin; Xu, Mengjian; Zang, Xiaofei; Peng, Yan; Zhu, Yiming
2016-11-01
The influence of the inner disk radius r, the filling ratio α, numbers of sectors N, and the gap g on transmission response for corrugated metallic disk (CMD) with single C-shaped resonator(CSR) has been fully studied. The results indicate that varying parameters r can efficiently excite the higher order spoof localized surface plasmon modes in corrugated metallic disk. The relationship between the bright dipole and dark multipolar resonances presents the possibility of high Q dark resonances excitation. All results may be of great interest for diverse applications.
Ger, Rachel B; Mohamed, Abdallah S R; Awan, Musaddiq J; Ding, Yao; Li, Kimberly; Fave, Xenia J; Beers, Andrew L; Driscoll, Brandon; Elhalawani, Hesham; Hormuth, David A; Houdt, Petra J van; He, Renjie; Zhou, Shouhao; Mathieu, Kelsey B; Li, Heng; Coolens, Catherine; Chung, Caroline; Bankson, James A; Huang, Wei; Wang, Jihong; Sandulache, Vlad C; Lai, Stephen Y; Howell, Rebecca M; Stafford, R Jason; Yankeelov, Thomas E; Heide, Uulke A van der; Frank, Steven J; Barboriak, Daniel P; Hazle, John D; Court, Laurence E; Kalpathy-Cramer, Jayashree; Fuller, Clifton D
2017-09-11
Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) provides quantitative metrics (e.g. K(trans), ve) via pharmacokinetic models. We tested inter-algorithm variability in these quantitative metrics with 11 published DCE-MRI algorithms, all implementing Tofts-Kermode or extended Tofts pharmacokinetic models. Digital reference objects (DROs) with known K(trans) and ve values were used to assess performance at varying noise levels. Additionally, DCE-MRI data from 15 head and neck squamous cell carcinoma patients over 3 time-points during chemoradiotherapy were used to ascertain K(trans) and ve kinetic trends across algorithms. Algorithms performed well (less than 3% average error) when no noise was present in the DRO. With noise, 87% of K(trans) and 84% of ve algorithm-DRO combinations were generally in the correct order. Low Krippendorff's alpha values showed that algorithms could not consistently classify patients as above or below the median for a given algorithm at each time point or for differences in values between time points. A majority of the algorithms produced a significant Spearman correlation in ve of the primary gross tumor volume with time. Algorithmic differences in K(trans) and ve values over time indicate limitations in combining/comparing data from distinct DCE-MRI model implementations. Careful cross-algorithm quality-assurance must be utilized as DCE-MRI results may not be interpretable using differing software.
Looyenga, Brendan; VanOpstall, Calvin; Lee, Zion; Bell, Jed; Lodge, Evans; Wrobel, Katherine; Arnoys, Eric; Louters, Larry
2016-01-01
The facilitated glucose transporter GLUT1 (SLC2A1) is an important mediator of glucose homeostasis in humans. Though it is found in most cell types to some extent, the level of GLUT1 expression across different cell types can vary dramatically. Prior studies in erythrocytes—which express particularly high levels of GLUT1—have suggested that GLUT1 is able to form tetrameric complexes with enhanced transport activity. Whether dynamic aggregation of GLUT1 also occurs in cell types with more modest expression of GLUT1, however, is unclear. To address this question, we developed a genetically encoded bioluminescent Förster resonance energy transfer (BRET) assay using the luminescent donor Nanoluciferase and fluorescent acceptor mCherry. By tethering these proteins to the N-terminus of GLUT1 and performing saturation BRET analysis, we were able to demonstrate the formation of multimeric complexes in live cells. Parallel use of flow cytometry and immunoblotting further enabled us to estimate the density of GLUT1 proteins required for spontaneous oligomerization. These data provide new insights into the physiological relevance of GLUT1 multimerization as well as a new variant of BRET assay that is useful for measuring the interactions among other cell membrane proteins in live cells. PMID:27357903
Looyenga, Brendan; VanOpstall, Calvin; Lee, Zion; Bell, Jed; Lodge, Evans; Wrobel, Katherine; Arnoys, Eric; Louters, Larry
2016-06-30
The facilitated glucose transporter GLUT1 (SLC2A1) is an important mediator of glucose homeostasis in humans. Though it is found in most cell types to some extent, the level of GLUT1 expression across different cell types can vary dramatically. Prior studies in erythrocytes-which express particularly high levels of GLUT1-have suggested that GLUT1 is able to form tetrameric complexes with enhanced transport activity. Whether dynamic aggregation of GLUT1 also occurs in cell types with more modest expression of GLUT1, however, is unclear. To address this question, we developed a genetically encoded bioluminescent Förster resonance energy transfer (BRET) assay using the luminescent donor Nanoluciferase and fluorescent acceptor mCherry. By tethering these proteins to the N-terminus of GLUT1 and performing saturation BRET analysis, we were able to demonstrate the formation of multimeric complexes in live cells. Parallel use of flow cytometry and immunoblotting further enabled us to estimate the density of GLUT1 proteins required for spontaneous oligomerization. These data provide new insights into the physiological relevance of GLUT1 multimerization as well as a new variant of BRET assay that is useful for measuring the interactions among other cell membrane proteins in live cells.
Minimum emittance in electron storage rings with uniform or nonuniform dipoles.
Wang, C.-x.; Accelerator Systems Division
2009-06-01
A simple treatment of minimum emittance theory in storage rings is presented, favoring vector and matrix forms for a more concise picture. Both conventional uniform dipoles and nonuniform dipoles with bending radius variation are treated. Simple formulas are given for computing the minimum emittance, optimal lattice parameters, as well as effects of nonoptimal parameters. For nonuniform dipoles, analytical results are obtained for a three-piece sandwich dipole model. Minimization of the effective emittance for light sources is given in detail. Usefulness of gradient and/or nonuniform dipoles for reducing the effective emittance is addressed.
Shiftless nuclear magnetic resonance spectroscopy.
Wu, Chin H; Opella, Stanley J
2008-02-07
The acquisition and analysis of high resolution one- and two-dimensional solid-state nuclear magnetic resonance (NMR) spectra without chemical shift frequencies are described. Many variations of shiftless NMR spectroscopy are feasible. A two-dimensional experiment that correlates the dipole-dipole and dipole-dipole couplings in the model peptide , (15)N labeled N-acetyl-leucine is demonstrated. In addition to the resolution of resonances from individual sites in a single crystal sample, the bond lengths and angles are characterized by the two-dimensional powder pattern obtained from a polycrystalline sample.
Balakrishnan, Umamaheswari; Amboiram, Prakash; Ninan, Binu; Chandrasekar, Anupama; Rangasami, Rajeswaran
2017-01-01
To assess the spectrum of Magnetic Resonance Imaging (MRI) abnormalities among preterm babies at term equivalent age using objective scoring and to study the association among MRI variables. Ninety-four preterm babies born at ≤32 wk of gestation and / or birth weight ≤ 1500 g at term equivalent age who underwent cranial MRI between April 2011 and August 2012 and the MRI interpreted by experienced radiologists were studied. In 2014, the MRI was retrospectively re-interpreted by the same radiologists using an objective scoring system described by Kidokoro. Spectrum of MRI abnormalities, their association with perinatal variables and correlation among white matter (WM), grey matter and cerebellar scores were analyzed. MRI abnormalities observed were WM signal abnormality (24 %), lateral ventricular dilatation (16 %), WM cystic abnormality (13 %), deep grey matter signal abnormality (9 %), cerebellar volume reduction (9 %) and deep grey matter volume reduction (8 %). Sepsis was significantly associated with occurrence of WM and cerebellar abnormalities (p < 0.05). WM scores did not show significant correlation with cortical grey matter and deep grey matter scores while cerebellar scores showed a weak positive correlation with WM (r = 0.33), cortical grey matter (r = 0.27) and deep grey matter scores (r = 0.22). MRI abnormalities are common in preterm infants, with 60 % showing some abnormality at term equivalent age. Among perinatal characteristics, sepsis was identified as risk factor for WM and cerebellar injury. Grey matter abnormality occurs independent of WM abnormality. Cerebellar abnormalities appear to coexist with either WM or grey matter changes.
NASA Astrophysics Data System (ADS)
Abdullah, Osama Mahmoud
Myocardial microstructure plays an important role in sustaining the orchestrated beating motion of the heart. Several microstructural components, including myocytes and auxiliary cells, extracellular space, and blood vessels provide the infrastructure for normal heart function, including excitation propagation, myocyte contraction, delivery of oxygen and nutrients, and removing byproduct wastes. Cardiac diseases cause deleterious changes to some or all of these microstructural components in the detrimental process of cardiac remodeling. Since heart failure is among the leading causes of death in the world, new and novel tools to noninvasively characterize heart microstructure are needed for monitoring and staging of cardiac disease. In this regards, diffusion magnetic resonance imaging (MRI) provides a promising framework to probe and quantify tissue microstructure without the need for exogenous contrast agent. As diffusion in 3-dimensional space is characterized by the diffusion tensor, MR diffusion tensor imaging (DTI) is being used to noninvasively measure anisotropic diffusion, and thus the magnitude and spatial orientation of microstructural organization of tissues, including the heart. However, even though in vivo cardiac DTI has become more clinically available, to date the origin and behavior of different microstructural components on the measured DTI signal remain to be explicitly specified. The presented studies in this work demonstrate that DTI can be used as a noninvasive and contrast-free imaging modality to characterize myocyte size and density, extracellular collagen content, and the directional magnitude of blood flow. The identified applications are expected to provide metrics to enable physicians to detect, quantify, and stage different microstructural components during progression of cardiac disease.
Electron-paramagnetic-resonance parameters of molybdenum(V) in sulphite oxidase from chicken liver.
Lamy, M T; Gutteridge, S; Bary, R C
1980-01-01
A study has been made of e.p.r. signals due to Mo(V) in reduced sulphite oxidase (EC 1.8.3.1) from chicken liver. Reduction by SO3(2-), or photochemically in the presence of a deazaflavin derivative, produces spectra indistinguishable from one another. Three types of spectra from the enzyme were distingusihed and shown to correspond to single chemical species, since they could be simulated at both 9 and 35 GHz by using the same parameters. These were the low-pH form of the enzyme, with gav. 1.9805, the high-pH form, with gav. 1.9681 and a phosphate complex, with gav. 1.9741. The low-H form shows interaction with a single exchangeable proton, with A(1H)av. (hyperfine coupling constant) = 0.98 mT, probably in the form of an MoOH group. Parameters of the signals are compared with those for signals from xanthine oxidase and nitrate reductase. The signal from the phosphate complex of sulphite oxidase in unique among anion complexes of Mo-containing enzymes in showing no hyperfine coupling to protons. There is no evidence for additional weakly coupled protons or nitrogen nuclei in the sulphite oxidase signals. The possibility is considered that the enzymic mechanism involves abstraction of a proton and two electrons from HSO3- by a Mo = O group in the enzyme. PMID:6249254
NASA Astrophysics Data System (ADS)
Swanson, Ryan D.; Binley, Andrew; Keating, Kristina; France, Samantha; Osterman, Gordon; Day-Lewis, Frederick D.; Singha, Kamini
2015-02-01
The advection-dispersion equation (ADE) fails to describe commonly observed non-Fickian solute transport in saturated porous media, necessitating the use of other models such as the dual-domain mass-transfer (DDMT) model. DDMT model parameters are commonly calibrated via curve fitting, providing little insight into the relation between effective parameters and physical properties of the medium. There is a clear need for material characterization techniques that can provide insight into the geometry and connectedness of pore spaces related to transport model parameters. Here, we consider proton nuclear magnetic resonance (NMR), direct-current (DC) resistivity, and complex conductivity (CC) measurements for this purpose, and assess these methods using glass beads as a control and two different samples of the zeolite clinoptilolite, a material that demonstrates non-Fickian transport due to intragranular porosity. We estimate DDMT parameters via calibration of a transport model to column-scale solute tracer tests, and compare NMR, DC resistivity, CC results, which reveal that grain size alone does not control transport properties and measured geophysical parameters; rather, volume and arrangement of the pore space play important roles. NMR cannot provide estimates of more-mobile and less-mobile pore volumes in the absence of tracer tests because these estimates depend critically on the selection of a material-dependent and flow-dependent cutoff time. Increased electrical connectedness from DC resistivity measurements are associated with greater mobile pore space determined from transport model calibration. CC was hypothesized to be related to length scales of mass transfer, but the CC response is unrelated to DDMT.
Quantum electrodynamics and plasmonic resonance of metallic nanostructures.
Zhang, Mingliang; Xiang, Hongping; Zhang, Xu; Lu, Gang
2016-04-20
Plasmonic resonance of a metallic nanostructure results from coherent motion of its conduction electrons driven by incident light. At the resonance, the induced dipole in the nanostructure is proportional to the number of the conduction electrons, hence 10(7) times larger than that in an atom. The interaction energy between the induced dipole and fluctuating virtual field of the incident light can reach a few tenths of an eV. Therefore, the classical electromagnetism dominating the field may become inadequate. We propose that quantum electrodynamics (QED) may be used as a fundamental theory to describe the interaction between the virtual field and the oscillating electrons. Based on QED, we derive analytic expressions for the plasmon resonant frequency, which depends on three easily accessible material parameters. The analytic theory reproduces very well the experimental data, and can be used in rational design of materials for plasmonic applications.
Development of Cellular Magnetic Dipoles in Magnetotactic Bacteria
Faivre, Damien; Fischer, Anna; Garcia-Rubio, Inés; Mastrogiacomo, Giovanni; Gehring, Andreas U.
2010-01-01
Magnetotactic bacteria benefit from their ability to form cellular magnetic dipoles by assembling stable single-domain ferromagnetic particles in chains as a means to navigate along Earth's magnetic field lines on their way to favorable habitats. We studied the assembly of nanosized membrane-encapsulated magnetite particles (magnetosomes) by ferromagnetic resonance spectroscopy using Magnetospirillum gryphiswaldense cultured in a time-resolved experimental setting. The spectroscopic data show that 1), magnetic particle growth is not synchronized; 2), the increase in particle numbers is insufficient to build up cellular magnetic dipoles; and 3), dipoles of assembled magnetosome blocks occur when the first magnetite particles reach a stable single-domain state. These stable single-domain particles can act as magnetic docks to stabilize the remaining and/or newly nucleated superparamagnetic particles in their adjacencies. We postulate that docking is a key mechanism for building the functional cellular magnetic dipole, which in turn is required for magnetotaxis in bacteria. PMID:20713012
Tagliafico, Alberto S.; Tagliafico, Giulio
2014-01-01
Abstract The objective of the study was to define and quantitatively evaluate the fascicular ratio (FR) on magnetic resonance imaging (MRI) in patients with peripheral neuropathies compared with healthy controls. Forty control subjects (20 women, 20 men; age, 44.6 ± 13.4 years) and 40 patients with peripheral neuropathy (22 women, 18 men; age, 50.3 ± 10.2 years) were examined with a standard 3T MRI protocol. With customized software (with semiautomatic and automatic interface), the hypointense and hyperintense areas of the peripheral nerves corresponding to fascicular and nonfascicular tissue were examined on T1-weighted sequences. The ratio of fascicular pixels to total pixels was called FR. Correlation with FR calculated on high-resolution ultrasound was performed. The statistical analysis included the Mann–Whitney U test of controls versus patients, the receiver operating characteristic (ROC) analysis, and the subgroup analysis of patients according to etiologies of neuropathy. Intraobserver and interobserver agreement was calculated based on the evaluation made by 3 readers. Finally, a complete automatic evaluation was performed. On MRI, FRs were significantly increased in patients compared with controls (FR, 76.7 ± 15.1 vs 56 ± 12.3; P < 0.0001 for the semiautomatic interface; and FR 66.3 ± 17.5 vs 47.8 ± 18.4; P < 0.0001 for the automatic interface). The increase in FR was caused mainly by an increase in the hypointense part of the nerve. This observation was valid for all causes of neuropathies. ROC analysis found an area under the curve of 0.75 (95% confidence interval, 0.44–0.81) for FR to discriminate neuropathy from control. The correlation coefficient between MRI and ultrasound was significant (r = 0.49; 95% confidence interval for r, 0.21–0.70; P = 0.012). With the semiautomated evaluation, the mean intraobserver agreement was good (K = 0.86). The interobserver agreements were also good (reader 1
NASA Astrophysics Data System (ADS)
Ashasi-Sorkhabi, Ali; Malekghasemi, Hadi; Ghaemmaghami, Amirreza; Mercan, Oya
2017-02-01
As structures are constructed more slender and taller, their vibrational response and its mitigation become challenging design considerations. Tuned liquid dampers (TLDs) are cost effective and low maintenance vibration absorbers that can be used to suppress structural vibrations. A TLD dissipates energy through liquid boundary layer friction, free surface contamination, and wave breaking. The dynamic characteristics of the TLD and its interaction with the structure is quite complex. In this paper, using a state-of-the-art experimental testing method, namely real-time hybrid simulation (RTHS), a comprehensive parametric study is conducted to investigate the effectiveness of TLDs. During RTHS the TLD response is obtained experimentally while the structure is modeled in a computer, thus capturing the TLD-structure interaction in real-time. By keeping the structure as the analytical model, RTHS offers a unique flexibility in which a wide range of influential parameters can be investigated without modifying the experimental setup. The parameters considered in this study with a wide range of variation include TLD/structure mass ratio, TLD/structure frequency ratio, and structural damping ratio. Additionally, the accuracy of FVM/FEM method that couples the finite volume and finite element approaches to model the liquid and solid domains to capture TLD- structure interaction is assessed experimentally. Results obtained in this study, will not only lead to a better understanding of TLDs and their interaction with the structures but also, contribute to the enhanced design of these devices which will in turn result in their wide-spread application.
Gasior, Katarzyna; Martynkien, Tadeusz; Urbanczyk, Waclaw
2014-12-10
We experimentally studied the influence of different constructional parameters on the performance of surface plasmon resonance (SPR) sensors based on a commercially available polymer step-index multimode fiber. For the first time, to the best of our knowledge, we experimentally investigated the influence of polishing depth on the characteristics of SPR sensors based on a straight multimode fiber. We also examined the impact of sensing length on the spectral position and strength of the SPR in side-polished straight fibers. To clarify literature contradictions concerning the effect of fiber bending on SPR, we experimentally investigated the performance of U-bent SPR sensing probes based on multimode fibers. We have shown that the SPR can be significantly amplified by bending the polymer fiber with stripped cladding. We also demonstrated that the side-polishing of U-bent sensing probes has little impact on their performance.
Dunn, Michael E; Leal, Luiz C; Wiarda, Dorothea; Arbanas, Goran
2008-01-01
The large size of resonance parameter covariance matrices (RPCM) in the actinide region often renders them impractical for dissemination via ENDF. Therefore, a method of approximating the RPCM by a much smaller group-wise covariance matrix (GWCM) is described, implemented, and examined. In this work, 233U RPCM is used to generate GWCM's for the 44 group AMPX, 100 group GE, 171 group VITAMIN-C, and 240 group CSWEG. Each of these GWCM's is then used to compute group-wise uncertainties for the groups of the remaining group structures. The group-wise uncertainties thus obtained are compared with those obtained from a full RPCM, i.e. without the approximation. A systematic comparison of group-wise uncertainties based on GWCM's vs. RPCM, for a variety of group structures, will shed light on the validity of this approximation and may suggest which group structure(s) yield a GWCM that could be used in lieu of the RPCM.
Retardation effects in induced atomic dipole-dipole interactions
NASA Astrophysics Data System (ADS)
Graham, S. D.; McGuirk, J. M.
2017-02-01
We present mean-field calculations of azimuthally averaged retarded dipole-dipole interactions in a Bose-Einstein condensate induced by a laser, at both long and short wavelengths. Our calculations demonstrate that dipole-dipole interactions become significantly stronger at shorter wavelengths, by as much as 30-fold, due to retardation effects. This enhancement, along with the inclusion of the dynamic polarizability, indicate a method of inducing long-range interatomic interactions in neutral atom condensates at significantly lower intensities than previously realized.
Lithium electric dipole polarizability
Puchalski, M.; KePdziera, D.; Pachucki, K.
2011-11-15
The electric dipole polarizability of the lithium atom in the ground state is calculated including relativistic and quantum electrodynamics corrections. The obtained result {alpha}{sub E}=164.0740(5) a.u. is in good agreement with the less accurate experimental value of 164.19(1.08) a.u. The small uncertainty of about 3 parts per 10{sup 6} comes from the approximate treatment of quantum electrodynamics corrections. Our theoretical result can be considered as a benchmark for more general atomic structure methods and may serve as a reference value for the relative measurement of polarizabilities of the other alkali-metal atoms.
Superconducting dipole electromagnet
Purcell, John R.
1977-07-26
A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.
Sachdeva, Shagun; Song, Xiaoyan; Dham, Niti; Heath, Deneen M; DeBiasi, Roberta L
2015-02-15
Myocarditis causes significant morbidity and mortality in pediatric patients, with potential adverse outcomes including heart failure, transplantation requirement, and/or death. The objective of this study was to determine predictors of early and late poor outcomes, defined as requirement for extracorporeal membrane oxygenation, ventricular assist device, transplantation, or death in pediatric myocarditis patients. A retrospective cohort study was conducted to evaluate pediatric myocarditis presenting over a 5-year period at a pediatric institution. Patients were identified using an institutional heart failure database and International Classification of Diseases, Ninth Revision, discharge diagnosis codes for myocarditis and confirmed by review of medical records. Data extraction included epidemiologic factors, the presenting ejection fraction (EF), initial and peak troponin levels, brain natriuretic peptide (BNP) level, pathogen identification, cardiac magnetic resonance imaging (MRI), and outcomes. Univariate and multivariate regression was performed to identify variables predictive of outcomes. Because published pediatric cardiac MRI data are sparse, whether late enhancement was associated with specific clinical variables or predictive of outcomes was also evaluated. Fifty-eight patients were identified. The mean age was 10.5 years, 64% were male, 62% were Caucasian, 15% were African-American, and 23% were Hispanic or Asian. Eighty-one percent presented at the institution <1 week after symptom onset. Presenting EFs were normal (>50%) or mildly decreased (40% to 50%) in 48%, moderately decreased (30% to 40%) in 9%, and severely decreased (<30%) in 42%. Thirty patients (52%) underwent viral studies; 17 of these (56%) had acute viral origins of myocarditis identified, including 8 with parvovirus (2 with influenza coinfection), 7 with enterovirus, 1 with Epstein-Barr virus, and 1 with cytomegalovirus. Twenty-eight percent had poor outcomes. Univariate analysis
NASA Astrophysics Data System (ADS)
Ipek-Ugay, Selcan; Drießle, Toni; Ledwig, Michael; Guo, Jing; Hirsch, Sebastian; Sack, Ingolf; Braun, Jürgen
2015-02-01
We demonstrate the feasibility of low-cost tabletop MR elastography (MRE) for quantifying the complex shear modulus G∗ of small soft biological tissue samples as provided by pathologists. The MRE system was developed based on a tabletop MRI scanner equipped with a 0.5 T permanent magnet and a tissue sample holder mounted to a loudspeaker. A spin echo sequence was enhanced with motion-encoding gradients of 250 mT/m amplitude synchronized to acoustic vibration frequencies. Shear wave images suitable for elastography were acquired between vibration frequencies of 0.5 and 1 kHz in agarose, ultrasound gel, porcine liver, porcine skeletal muscle, and bovine heart with a spatial resolution of 234 μm pixel edge length. The measured frequency dependence of G∗ agreed well with previous work based on high-field MR systems. The ratio between loss and storage moduli was highest in liver and ultrasound gel, followed by muscle tissue and agarose gel while ultrasound gel and liver showed similarly low storage moduli compared to the other samples. The shear wave to noise ratio is an important imaging criteria for MRE and was about 4.2 times lower for the preliminary setup of the 0.5 T tabletop system compared to a 7 T animal scanner. In the future, the new tabletop MRE system may serve as a low cost device for preclinical research on the correlation of viscoelastic parameters with histopathology of biological samples.
Nighoghossian, N; Berthezene, Y; Adeleine, P; Wiart, M; Damien, J; Derex, L; Itti, R; Froment, J C; Trouillas, P
1999-01-01
A simultaneous decrease of cerebral blood volume (CBV) and cerebral blood flow (CBF) has been described after subcortical stroke with positron emission tomography. However, this imaging modality cannot be applied routinely to stroke patients. Dynamic susceptibility contrast-enhanced MRI techniques (DSC-MRI) might be interesting in the assessment of these effects. Dynamic T2-weighted echo planar imaging was used to produce DSC-MR images during an intravenous bolus injection of gadopentetate dimeglumine in 9 patients who experienced a subcortical stroke involving thalamus or basal ganglia and in 8 control subjects. A series of 50 consecutive images at 1-second intervals was acquired at the anatomic level of the centrum semiovale quite distant from the subcortical lesion, rCBF and rCBV were determined over frontal and parietal regions of interest and through the entire cortical mantle. DSC-MRI enabled the detection of hemodynamic changes induced by subcortical stroke. Analysis of rCBV and rCBF values showed that the hemodynamic parameters were significantly decreased on the affected side. In controls mean rCBF and rCBV values recorded over the whole cortical mantle of each hemisphere showed no significant interhemispheric asymmetry.
Localized surface plasmon resonance modes on an asymmetric cylindrical nanorod dimer
NASA Astrophysics Data System (ADS)
Wang, Rui-Bing; Zhang, Zhi-Dong; Jiao, Guo-Tai; Xue, Chen-Yang; Yan, Shu-Bin; Wang, Hongyang
2016-08-01
The extinction spectra and electric field distribution of an asymmetric cylindrical nanorod dimer (ACND) are calculated by discrete dipole approximation. The ACND is composed of two linear orders of cylindrical silver nanorods with different radii and lengths. The effects of the structural parameters of ACND on the localized surface plasmon resonance (LSPR) mode are also studied. Results show two resonance peaks in the extinction spectra of ACND: the higher-energy anti-bonding mode and the lower-energy bonding mode. The interaction of two hybridization plasmonic resonance modes produces an asymmetric line shape in the extinction spectra, which is considered to be a Fano resonance profile.
Dianat, Seyed Saeid; Carter, H Ballentine; Schaeffer, Edward M; Hamper, Ulrik M; Epstein, Jonathan I; Macura, Katarzyna J
2015-10-01
Purpose of this pilot study was to correlate quantitative parameters derived from the multiparametric magnetic resonance imaging (MP-MRI) of the prostate with results from MRI guided transrectal ultrasound (MRI/TRUS) fusion prostate biopsy in men with suspected prostate cancer. Thirty-nine consecutive patients who had 3.0T MP-MRI and subsequent MRI/TRUS fusion prostate biopsy were included and 73 MRI-identified targets were sampled by 177 cores. The pre-biopsy MP-MRI consisted of T2-weighted, diffusion weighted (DWI), and dynamic contrast enhanced (DCE) images. The association of quantitative MRI measurements with biopsy histopathology findings was assessed by Mann-Whitney U- test and Kruskal-Wallis test. Of 73 targets, biopsy showed benign prostate tissue in 46 (63%), cancer in 23 (31.5%), and atypia/high grade prostatic intraepithelial neoplasia in four (5.5%) targets. The median volume of cancer-positive targets was 1.3 cm3. The cancer-positive targets were located in the peripheral zone (56.5%), transition zone (39.1%), and seminal vesicle (4.3%). Nine of 23 (39.1%) cancer-positive targets were higher grade cancer (Gleason grade > 6). Higher grade targets and cancer-positive targets compared to benign lesions exhibited lower mean apparent diffusion coefficient (ADC) value (952.7 < 1167.9 < 1278.9), and lower minimal extracellular volume fraction (ECF) (0.13 < 0.185 < 0.213), respectively. The difference in parameters was more pronounced between higher grade cancer and benign lesions. Our findings from a pilot study indicate that quantitative MRI parameters can predict malignant histology on MRI/TRUS fusion prostate biopsy, which is a valuable technique to ensure adequate sampling of MRI-visible suspicious lesions under TRUS guidance and may impact patient management. The DWI-based quantitative measurement exhibits a stronger association with biopsy findings than the other MRI parameters.
Conceptual design of Dipole Research Experiment (DREX)
NASA Astrophysics Data System (ADS)
Qingmei, XIAO; Zhibin, WANG; Xiaogang, WANG; Chijie, XIAO; Xiaoyi, YANG; Jinxing, ZHENG
2017-03-01
A new terrella-like device for laboratory simulation of inner magnetosphere plasmas, Dipole Research Experiment, is scheduled to be built at the Harbin Institute of Technology (HIT), China, as a major state scientific research facility for space physics studies. It is designed to provide a ground experimental platform to reproduce the inner magnetosphere to simulate the processes of trapping, acceleration, and transport of energetic charged particles restrained in a dipole magnetic field configuration. The scaling relation of hydromagnetism between the laboratory plasma of the device and the geomagnetosphere plasma is applied to resemble geospace processes in the Dipole Research Experiment plasma. Multiple plasma sources, different kinds of coils with specific functions, and advanced diagnostics are designed to be equipped in the facility for multi-functions. The motivation, design criteria for the Dipole Research Experiment experiments and the means applied to generate the plasma of desired parameters in the laboratory are also described. Supported by National Natural Science Foundation of China (Nos. 11505040, 11261140326 and 11405038), China Postdoctoral Science Foundation (Nos. 2016M591518, 2015M570283) and Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (No. 2017008).
Conceptual design of Dipole Research Experiment (DREX)
NASA Astrophysics Data System (ADS)
Xiao, Qingmei; Wang, Zhibin; Wang, Xiaogang; Xiao, Chijie; Yang, Xiaoyi; Zheng, Jinxing
2017-03-01
A new terrella-like device for laboratory simulation of inner magnetosphere plasmas, Dipole Research Experiment, is scheduled to be built at the Harbin Institute of Technology (HIT), China, as a major state scientific research facility for space physics studies. It is designed to provide a ground experimental platform to reproduce the inner magnetosphere to simulate the processes of trapping, acceleration, and transport of energetic charged particles restrained in a dipole magnetic field configuration. The scaling relation of hydromagnetism between the laboratory plasma of the device and the geomagnetosphere plasma is applied to resemble geospace processes in the Dipole Research Experiment plasma. Multiple plasma sources, different kinds of coils with specific functions, and advanced diagnostics are designed to be equipped in the facility for multi-functions. The motivation, design criteria for the Dipole Research Experiment experiments and the means applied to generate the plasma of desired parameters in the laboratory are also described. Supported by National Natural Science Foundation of China (Nos. 11505040, 11261140326 and 11405038), China Postdoctoral Science Foundation (Nos. 2016M591518, 2015M570283) and Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (No. 2017008).
NASA Astrophysics Data System (ADS)
Hoffman, Yehuda; Pomarède, Daniel; Tully, R. Brent; Courtois, Hélène M.
2017-01-01
Our Local Group of galaxies is moving with respect to the cosmic microwave background (CMB) with a velocity 1 of V CMB = 631 ± 20 km s‑1 and participates in a bulk flow that extends out to distances of ~20,000 km s‑1 or more 2-4 . There has been an implicit assumption that overabundances of galaxies induce the Local Group motion 5-7 . Yet underdense regions push as much as overdensities attract 8 , but they are deficient in light and consequently difficult to chart. It was suggested a decade ago that an underdensity in the northern hemisphere roughly 15,000 km s‑1 away contributes significantly to the observed flow 9 . We show here that repulsion from an underdensity is important and that the dominant influences causing the observed flow are a single attractor — associated with the Shapley concentration — and a single previously unidentified repeller, which contribute roughly equally to the CMB dipole. The bulk flow is closely anti-aligned with the repeller out to 16,000 ± 4,500 km s‑1. This 'dipole repeller' is predicted to be associated with a void in the distribution of galaxies.
Relativistic theory of nuclear magnetic resonance parameters in a Gaussian basis representation
Kutzelnigg, Werner; Liu Wenjian
2009-07-28
The calculation of NMR parameters from relativistic quantum theory in a Gaussian basis expansion requires some care. While in the absence of a magnetic field the expansion in a kinetically balanced basis converges for the wave function in the mean and for the energy with any desired accuracy, this is not necessarily the case for magnetic properties. The results for the magnetizability or the nuclear magnetic shielding are not even correct in the nonrelativistic limit (nrl) if one expands the original Dirac equation in a kinetically balanced Gaussian basis. This defect disappears if one starts from the unitary transformed Dirac equation as suggested by Kutzelnigg [Phys. Rev. A 67, 032109 (2003)]. However, a new difficulty can arise instead if one applies the transformation in the presence of the magnetic field of a point nucleus. If one decomposes certain contributions, the individual terms may diverge, although their sum is regular. A controlled cancellation may become difficult and numerical instabilities can arise. Various ways exist to avoid these singularities and at the same time get the correct nrl. There are essentially three approaches intermediate between the transformed and the untransformed formulation, namely, the bispinor decomposition, the decomposition of the lower component, and the hybrid unitary transformation partially at operator and partially at matrix level. All three possibilities were first considered by Xiao et al. [J. Chem. Phys. 126, 214101 (2007)] in a different context and in a different nomenclature. Their analysis and classification in a more general context are given here for the first time. Use of an extended balanced basis has no advantages and has other drawbacks and is not competitive, while the use of a restricted magnetic balance basis can be justified.
Ipek-Ugay, Selcan; Drießle, Toni; Ledwig, Michael; Guo, Jing; Hirsch, Sebastian; Sack, Ingolf; Braun, Jürgen
2015-02-01
We demonstrate the feasibility of low-cost tabletop MR elastography (MRE) for quantifying the complex shear modulus G(∗) of small soft biological tissue samples as provided by pathologists. The MRE system was developed based on a tabletop MRI scanner equipped with a 0.5 T permanent magnet and a tissue sample holder mounted to a loudspeaker. A spin echo sequence was enhanced with motion-encoding gradients of 250 mT/m amplitude synchronized to acoustic vibration frequencies. Shear wave images suitable for elastography were acquired between vibration frequencies of 0.5 and 1 kHz in agarose, ultrasound gel, porcine liver, porcine skeletal muscle, and bovine heart with a spatial resolution of 234 μm pixel edge length. The measured frequency dependence of G(∗) agreed well with previous work based on high-field MR systems. The ratio between loss and storage moduli was highest in liver and ultrasound gel, followed by muscle tissue and agarose gel while ultrasound gel and liver showed similarly low storage moduli compared to the other samples. The shear wave to noise ratio is an important imaging criteria for MRE and was about 4.2 times lower for the preliminary setup of the 0.5 T tabletop system compared to a 7 T animal scanner. In the future, the new tabletop MRE system may serve as a low cost device for preclinical research on the correlation of viscoelastic parameters with histopathology of biological samples. Copyright © 2014 Elsevier Inc. All rights reserved.
Black Saturn with a dipole ring
Yazadjiev, Stoytcho S.
2007-09-15
We present a new stationary, asymptotically flat solution of 5D Einstein-Maxwell gravity describing a Saturn-like black object: a rotating black hole surrounded by a rotating dipole black ring. The solution is generated by combining the vacuum black Saturn solution and the vacuum black ring solution with appropriately chosen parameters. Some basic properties of the solution are analyzed and the basic quantities are calculated.
NASA Astrophysics Data System (ADS)
Tonchev, A. P.; Kwan, E.; Raut, R.; Rusev, G.; Tornow, W.; Hammond, S.; Kelley, J. H.; Tsoneva, N.; Lenske, H.
2013-03-01
In stable and weakly bound neutron-rich nuclei, a resonance-like concentration of dipole states has been observed for excitation energies around the neutron separation energy. This clustering of strong dipole states has been named the pygmy dipole resonance in contrast to the giant dipole resonance that dominates the E1 response. Understanding the pygmy resonance is presently of great interest in nuclear structure and nuclear astrophysics. High-sensitivity studies of E1 and M1 transitions in N=82 nuclei using the quasi monoenergetic and 100% linearly-polarized photon beams from High-Intensity-Gamma-Ray Source facility is presented. The nuclear dipole-strength distribution of the pygmy resonance has been measured and novel information about the character of this mode of excitation has been obtained. The data are compared with predictions from statistical and quasiparticle random-phase approximation models.
Antoniou, John; Epure, Laura M.; Michalek, Arthur J.; Grant, Michael P.; Iatridis, James C.; Mwale, Fackson
2013-01-01
Purpose To establish relationships between quantitative magnetic resonance imaging (qMRI) and biomechanical parameters to help inform and interpret alterations of human intervertebral discs (IVD) with different grades of degeneration. Materials and Methods The properties of the nucleus pulposus (NP) and annulus fibrosus (AF) tissues of each IVD of 10 lumbar spines (range 32–77 years) were analyzed by qMRI (relaxation times T1 and T2, magnetization transfer ratio MTR and apparent diffusion coefficient ADC), and tested in confined compression and dynamic shear. Results T1 and T2 significantly decreased in both the NP and AF with increasing degeneration grades while the MTR increased significantly with grade 4. In contrast with the others qMRI parameters, the ADC had a tendency to decrease with increasing grade. Disc degeneration caused a decrease in the aggregate modulus, hydraulic permeability and shear modulus magnitude along with an increase in phase angle in the AF. On the other hand, disc degeneration of NPs decreased the shear modulus and the phase angle. Conclusion Our studies indicate that qMRI can be used as a non-invasive diagnostic tool in the detection of IVDs properties with potential to help interpret and to detect early, middle and late stages of degeneration. QMRI of the human IVD can therefore become a very important diagnostic assessment tool in determining the functional state of the disc. PMID:23633131
Isselhardt, Brett H.
2011-09-01
Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of ^{235}U/^{238}U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.
Ríos, Stella Maris; Barquin, Mercedes; Katusich, Ofelia; Nudelman, Norma
2014-01-01
Oil spill in the Central Patagonian zone was studied to evaluate if any relationship exists between the parameters used to characterize weathering spilled oil and soil toxicity for two plant species and to evaluate if the phytotoxicity to local species would be a good index for the soil contamination. Nuclear magnetic resonance (NMR) structural indexes and column chromatography compositional indexes were determined to characterize the oil spill in the soil samples. Bioassays were also carried out using Lactuca sativa L (reference) and Atriplex lampa (native species) as test organisms. Measurements of the total petroleum hydrocarbon (TPH) and the electrical conductivity (EC) of the soil were carried out to evaluate the effect on the bioassays. The principal components analysis of the parameters determined by NMR, compositional indexes, EC, TPH, and toxicology data shows that the first three principal components accounted for the 78% of the total variance (40%, 25%, and 13% for the first, second, and third PC, respectively). A good agreement was found between information obtained by compositional indexes and NMR structural indexes. Soil toxicity increases with the increase of EC and TPH. Other factors, such as, the presence of branched and aromatic hydrocarbons is also significant. The statistical evaluation showed that the Euclidean distances (3D) between the background and each one of the samples might be a better indicator of the soil contamination, compared with chemical criterion of TPH.
Ogura, Akio; Tamura, Takayuki; Ozaki, Masanori; Doi, Tsukasa; Fujimoto, Koji; Miyati, Tosiaki; Ito, Yukiko; Maeda, Fumie; Tarewaki, Hiroyuki; Takahashi, Mitsuyuki
2015-01-01
The aim of the study was to investigate the causes of apparent diffusion coefficient (ADC) measurement errors and to determine the optimal scanning parameters that are independent of the field strength and vendors of the magnetic resonance (MR) system. Brain MR images of 10 healthy volunteers were scanned using 6 MR scanners of different field strengths and vendors in 2 different institutions. Ethical review board approvals were obtained for this study, and all volunteers gave their informed consents. Coefficient of variation (CV) of ADC values were compared for their differences in various MR scanners and in the scanned subjects. The CV of ADC values for 6 different scanners of 6 brains was 3.32%. The CV for repeated measurements in 1 day (10 scans per day) and in 10 days (scan per day for 10 days) for 1 subject was 1.72% and 2.96%, respectively (n = 5, P < 0.001). The CV of measurements for 10 healthy subjects was 5.22%. The measurement errors of the ADC values for 6 different MR units in 1 subject were higher than the intrascanner variance for the same subject but were lower than the intersubject variance for the same scanner. The variance in the ADC values for different MR scanners is reasonably small if appropriate scanning parameters (repetition time, >3000 ms; echo time, minimum; and high enough signal-to-noise ratio of high-b diffusion-weighted image) are used.
Pygmy Dipole Strength in Exotic Nuclei and the Equation of State
Klimkiewicz, A.; Adrich, P.; Paar, N.; Vretenar, D.; Fallot, M.; Boretzky, K.; Aksouh, F.; Chatillon, A.; Pramanik, U. Datta; Emling, H.; Ershova, O.; Geissel, H.; Gorska, M.; Heil, M.; Hellstroem, M.; Jones, K. L.; Kurz, N.; Litvinov, Y.; Mahata, K.; Simon, H.
2009-08-26
A concentration of dipole strength at energies below the giant dipole resonance was observed in neutron-rich nuclei around {sup 132}Sn in an experiment using the FRS-LAND setup. This so-called 'pygmy' dipole strength can be related to the parameters of the symmetry energy and to the neutron skin thickness on the grounds of a relativistic quasiparticle random-phase approximation. Using this ansatz and the experimental findings for {sup 130}Sn and {sup 132}Sn, we derive a value of the symmetry energy pressure of p-bar{sub 0} = 2.2+-0.5 MeV/fm{sup 3}. Neutron skin thicknesses of R{sub n}-R{sub p} 0.23+-0.03 fm and 0.24+-0.03 fm for {sup 130}Sn and {sup 132}Sn, respectively, have been determined. Preliminary results on {sup 68}Ni from a similar experiment using an improved setup indicate an enhanced cross section at low energies, while the results for {sup 58}Ni are in accordance with results from photoabsorption measurements.
Focardi, Marta; Cameli, Matteo; Carbone, Salvatore Francesco; Massoni, Alberto; De Vito, Raffaella; Lisi, Matteo; Mondillo, Sergio
2015-01-01
Right ventricle fractional area change (RVFAC), tissue Doppler and M-mode measurements of tricuspid systolic motion [tricuspid Sm and tricuspid annular plane systolic excursion (TAPSE)], and 3D echocardiography are the current non-invasive methods for the quantification of RV systolic function; RV deformation analysis by speckle-tracking echocardiography (STE) has recently allowed the analysis of RV performance. Using cardiac magnetic resonance (CMR) as the reference standard, this study aimed at exploring the correlation between the traditional (fractional shortening, s'RV, TAPSE) and innovative (strain) echocardiographic parameters and RV ejection fraction (RVEF) measured by CMR. CMR and transthoracic echo-Doppler were performed in 63 patients referred for clinical assessment. Twenty-one presented the suspicion of myocarditis, 8 presented idiopathic dilated cardiomyopathy, 10 hypertrophic cardiomyopathy, 10 arrhythmogenic right ventricular dysplasia (ARVD), 5 infiltrative cardiomyopathy, and 9 other reasons. RVEF was measured by magnetic resonance imaging (MRI). RVFAC, tricuspid S', and TAPSE were calculated in all patients. RV longitudinal strain (RVLS) by STE was assessed by averaging RV free-wall segments (free-wall RVLS) and by averaging all segments (global RVLS). The ROC analysis was applied for the assessment of diagnostic accuracy. Good correlations were found for TAPSE, tricuspid S', and global RVLS with RVEF (r = 0.45, r = 0.52, and r = -0.71, respectively; P = 0.01 for all). Close correlations between free-wall RVLS and RVFAC with RVEF were found (r = -0.86 and r = 0.77, respectively; P < 0.0001 for both). Furthermore, free-wall RVLS demonstrated the highest diagnostic accuracy [area under curve (AUC) 0.92] and good sensitivity and specificity of 96 and 93%, respectively, to predict reduced RVEF <45%, using a cut-off value of less than -17.0%. In a heterogeneous group of patients referred to CMR evaluation, conventional (TAPSE, FAC, and tricuspid S
Controlling magnetic dipole transition with magnetic plasmonic structures.
Feng, Tianhua; Zhou, Ying; Liu, Dahe; Li, Jensen
2011-06-15
A plasmonic structure with double gold patches is proposed for enhancing the spontaneous emission of a magnetic dipole transition through a magnetic hot area. A Purcell factor of nearly 2000 can be obtained at optical frequencies together with a low sensitivity in spatial and spectral mismatches between the light emitter and the resonance mode. The associated resonance can be tuned from the visible to the IR frequencies, enabling efficient control of forbidden transitions using plasmonic structures.
Electromagnetic moments and electric dipole transitions in carbon isotopes
NASA Astrophysics Data System (ADS)
Suzuki, Toshio; Sagawa, Hiroyuki; Hagino, Kouichi
2003-07-01
We carry out shell model calculations to study electromagnetic moments and electric dipole transitions of C isotopes. We point out the configuration dependence of the quadrupole and magnetic moments of the odd C isotopes, which will be useful to find out the deformations and the spin parities of the ground states of these nuclei. We also study the electric dipole states of C isotopes, focusing on the interplay between low energy pigmy strength and giant dipole resonances. As far as the energies of the resonances are concerned, reasonable agreement is obtained with available experimental data for the photoreaction cross sections in 12C, 13C, and 14C, both in the low energy region below ħω=14 MeV and in the high energy giant resonance region (14 MeV <ħω⩽30 MeV). The calculated transition strength below the giant dipole resonance (ħω⩽14 MeV) in C isotopes heavier than 15C is found to exhaust about 12 16 % of the classical Thomas-Reiche-Kuhn sum rule value and 50 80 % of the cluster sum rule value.
Dimopoulos, Johannes Lang, Stefan; Kirisits, Christian; Fidarova, Elena F.; Berger, Daniel; Georg, Petra; Doerr, Wolfgang; Poetter, Richard
2009-09-01
Purpose: To investigate the value of dose-volume histogram (DVH) parameters for predicting local control in magnetic resonance (MR) image-guided brachytherapy (IGBT) for patients with cervical cancer. Methods and Materials: Our study population consists of 141 patients with cervical cancer (Stages IB-IVA) treated with 45-50 Gy external beam radiotherapy plus four times 7 Gy IGBT with or without cisplatin. Gross tumor volume (GTV), high-risk clinical target volume (HRCTV), and intermediate-risk clinical target volume (IRCTV) were contoured, and DVH parameters (minimum dose delivered to 90% of the volume of interest [D90] and D100) were assessed. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model ({alpha}/{beta} = 10 Gy). Groups were defined for patients with or without local recurrence (LR) in the true pelvis for tumor size at diagnosis (GTV at diagnosis [GTVD] of 2-5 cm (Group 1) or greater than 5 cm (Group 2) and for tumor size response at IGBT (HRCTV) of 2-5 cm (Group 2a) or greater than 5 cm (Group 2b). Results: Eighteen LRs were observed. The most important DVH parameters correlated with LR were the D90 and D100 for HRCTV. Mean D90 and D100 values for HRCTV were 86 {+-} 16 and 65 {+-} 10 Gy, respectively. The D90 for HRCTV greater than 87 Gy resulted in an LR incidence of 4% (3 of 68) compared with 20% (15 of 73) for D90 less than 87 Gy. The effect was most pronounced in the tumor group (Group 2b). Conclusions: We showed an increase in local control in IGBT in patients with cervical cancer with the dose delivered, which can be expressed by the D90 and D100 for HRCTV. Local control rates greater than 95% can be achieved if the D90 (EQD2) for HRCTV is 87 Gy or greater.
NASA Astrophysics Data System (ADS)
Osterman, Gordon; Keating, Kristina; Binley, Andrew; Slater, Lee
2016-06-01
We estimate parameters from the Katz and Thompson permeability model using laboratory complex electrical conductivity (CC) and nuclear magnetic resonance (NMR) data to build permeability models parameterized with geophysical measurements. We use the Katz and Thompson model based on the characteristic hydraulic length scale, determined from mercury injection capillary pressure estimates of pore throat size, and the intrinsic formation factor, determined from multisalinity conductivity measurements, for this purpose. Two new permeability models are tested, one based on CC data and another that incorporates CC and NMR data. From measurements made on forty-five sandstone cores collected from fifteen different formations, we evaluate how well the CC relaxation time and the NMR transverse relaxation times compare to the characteristic hydraulic length scale and how well the formation factor estimated from CC parameters compares to the intrinsic formation factor. We find: (1) the NMR transverse relaxation time models the characteristic hydraulic length scale more accurately than the CC relaxation time (R2 of 0.69 and 0.33 and normalized root mean square errors (NRMSE) of 0.16 and 0.21, respectively); (2) the CC estimated formation factor is well correlated with the intrinsic formation factor (NRMSE=0.23). We demonstrate that that permeability estimates from the joint-NMR-CC model (NRMSE=0.13) compare favorably to estimates from the Katz and Thompson model (NRMSE=0.074). This model advances the capability of the Katz and Thompson model by employing parameters measureable in the field giving it the potential to more accurately estimate permeability using geophysical measurements than are currently possible.
Pygmy dipole strength close to particle-separation energies --The case of the Mo isotopes
NASA Astrophysics Data System (ADS)
Rusev, G.; Grosse, E.; Erhard, M.; Junghans, A.; Kosev, K.; Schilling, K.-D.; Schwengner, R.; Wagner, A.
2006-03-01
The distribution of electromagnetic dipole strength in 92, 98, 100Mo has been investigated by photon scattering using bremsstrahlung from the new ELBE facility. The experimental data for well-separated nuclear resonances indicate a transition from a regular to a chaotic behaviour above 4MeV of excitation energy. As the strength distributions follow a Porter-Thomas distribution much of the dipole strength is found in weak and in unresolved resonances appearing as fluctuating cross section. An analysis of this quasi-continuum --here applied to nuclear resonance fluorescence in a novel way-- delivers dipole strength functions, which are combining smoothly to those obtained from (γ, n) data. Enhancements at 6.5MeV and at ˜ 9MeV are linked to the pygmy dipole resonances postulated to occur in heavy nuclei.
Real-time ECG emulation: a multiple dipole model for electrocardiography simulation.
Abkai, Ciamak; Hesser, Jürgen
2009-01-01
A new model for describing electrocardiography (ECG) is presented, which is based on multiple dipoles compared to standard single dipole approaches in vector electrocardiography. The multiple dipole parameters are derived from real data (e.g. four dipoles from 12-channel ECG) by solving the backward problem of ECG numerically. Results are transformed to a waveform description based on Gaussian mixture for every dimension of each dipole. These compact parameterized descriptors are used for a very realistic real-time simulation applying the forward solution of the proposed model.
OEDIPUS: Onium Evolution, Dipole Interaction and Perturbative Unitarisation Simulation
NASA Astrophysics Data System (ADS)
Salam, G. P.
1997-09-01
OEDIPUS is a Monte Carlo simulation program which can be used to determine the small- x evolution of a heavy onium using Mueller's colour dipole formulation, giving the full distribution of dipoles in rapidity and impact parameter. Routines are also provided which calculate onium-onium scattering amplitudes between individual pairs of onium configurations, making it possible to establish the contribution of multiple pomeron exchange terms to onium-onium scattering (the unitarisation corrections).
Derrien, Herve; Leal, Luiz C; Larson, Nancy M
2008-01-01
To obtain the resonance parameters in a single energy range up to 2.5 keV neutron energy and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the analysis code SAMMY. The most recent experimental data were analyzed in the energy range thermal to 2.5 keV. The experimental data were renormalized, aligned on a common energy scale, and corrected for residual background. Average neutron transmission and cross sections calculated with the new resonance parameters were compared to the corresponding experimental data and to ENDF/B-VI.
Ferrofluid Photonic Dipole Contours
NASA Astrophysics Data System (ADS)
Snyder, Michael; Frederick, Jonathan
2008-03-01
Understanding magnetic fields is important to facilitate magnetic applications in diverse fields in industry, commerce, and space exploration to name a few. Large electromagnets can move heavy loads of metal. Magnetic materials attached to credit cards allow for fast, accurate business transactions. And the Earth's magnetic field gives us the colorful auroras observed near the north and south poles. Magnetic fields are not visible, and therefore often hard to understand or characterize. This investigation describes and demonstrates a novel technique for the visualization of magnetic fields. Two ferrofluid Hele-Shaw cells have been constructed to facilitate the imaging of magnetic field lines [1,2,3,4]. We deduce that magnetically induced photonic band gap arrays similar to electrostatic liquid crystal operation are responsible for the photographed images and seek to mathematically prove the images are of exact dipole nature. We also note by comparison that our photographs are very similar to solar magnetic Heliosphere photographs.
Final Report: Levitated Dipole Experiment
Kesner, Jay; Mauel, Michael
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier, Phys. Plasmas, v13, p. 056111, 2006]. High-beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability makes LDX the longest pulse fusion confinement experiment now operating in the U.S. fusion program. In both supported and levitated configurations, detailed measurements are made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma is created by multifrequency electron cyclotron resonance heating allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole is levitated or supported, the peak thermal electron temperature is estimated to exceed 500 eV and peak densities reach 1.0E18 (1/m3). Several significant discoveries resulted from the routine investigation of plasma confinement with a magnetically-levitated dipole. For the first time, toroidal plasma with pressure approaching the pressure of the confining magnetic field was well-confined in steady-state without a toroidal magnetic field. Magnetic levitation proved to be reliable and is now routine. The dipole's cryostat allows up to three hours of "float time" between re-cooling with liquid helium and providing scientists unprecedented access to the physics of magnetizd plasma. Levitation eliminates field-aligned particle sources and sinks and results in a toroidal, magnetically-confined plasma where profiles are determined by cross
Highly Automated Dipole EStimation (HADES)
Campi, C.; Pascarella, A.; Sorrentino, A.; Piana, M.
2011-01-01
Automatic estimation of current dipoles from biomagnetic data is still a problematic task. This is due not only to the ill-posedness of the inverse problem but also to two intrinsic difficulties introduced by the dipolar model: the unknown number of sources and the nonlinear relationship between the source locations and the data. Recently, we have developed a new Bayesian approach, particle filtering, based on dynamical tracking of the dipole constellation. Contrary to many dipole-based methods, particle filtering does not assume stationarity of the source configuration: the number of dipoles and their positions are estimated and updated dynamically during the course of the MEG sequence. We have now developed a Matlab-based graphical user interface, which allows nonexpert users to do automatic dipole estimation from MEG data with particle filtering. In the present paper, we describe the main features of the software and show the analysis of both a synthetic data set and an experimental dataset. PMID:21437232
Highly Automated Dipole EStimation (HADES).
Campi, C; Pascarella, A; Sorrentino, A; Piana, M
2011-01-01
Automatic estimation of current dipoles from biomagnetic data is still a problematic task. This is due not only to the ill-posedness of the inverse problem but also to two intrinsic difficulties introduced by the dipolar model: the unknown number of sources and the nonlinear relationship between the source locations and the data. Recently, we have developed a new Bayesian approach, particle filtering, based on dynamical tracking of the dipole constellation. Contrary to many dipole-based methods, particle filtering does not assume stationarity of the source configuration: the number of dipoles and their positions are estimated and updated dynamically during the course of the MEG sequence. We have now developed a Matlab-based graphical user interface, which allows nonexpert users to do automatic dipole estimation from MEG data with particle filtering. In the present paper, we describe the main features of the software and show the analysis of both a synthetic data set and an experimental dataset.
NASA Astrophysics Data System (ADS)
Wang, Yong; Hong, Yan; Goh, Wang Ling; Mu, Xiaojing
2016-10-01
Dual-mode Lamb-wave resonator has become a powerful component for clock reference and sensing applications, enabling efficient compensations of temperature effects, concurrent measurements of multiple environmental parameters, etc. An equivalent circuit model for the dual-mode Lamb-wave resonator is indispensable as it provides a means as well as being an effective tool for evaluating device characteristics and to aid the designing of circuitry for the resonators. This could be the first time ever that an efficient equivalent-circuit model, i.e., modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonators is reported. Evaluated by experiments, this model attains noteworthy agreements on both the magnitudes and phases of Y11 and Y21 of the measurement results. Compared to literature, the proposed model is capable of modeling the dual resonances efficiently. Moreover, this work also proves more accurate when viewing the Y-parameters across a wide frequency range. The gained features of this model are most beneficial for the analysis of the dual-mode Lamb-wave resonator and also for the designing of circuits.
Yu, Jing; Huang, Dong-Ya; Xu, Hui-Xin; Li, Yang; Xu, Qing
2016-01-01
The aim of this study was to analyze the correlation between magnetic resonance imaging-based extramural vascular invasion (EMVI) and the prognostic clinical and histological parameters of stage T3 rectal cancers. Eighty-six patients with T3 stage rectal cancer who received surgical resection without neoadjuvant therapy were included. Magnetic resonance imaging-based EMVI scores were determined. Correlations between the scores and pretreatment carcinoembryonic antigen levels, tumor differentiation grade, nodal stage, and vascular endothelial growth factor expression were analyzed using Spearman rank coefficient analysis. Magnetic resonance imaging-based EMVI scores were statistically different (P = 0.001) between histological nodal stages (N0 vs N1 vs N2). Correlations were found between magnetic resonance imaging-based EMVI scores and tumor histological grade (rs = 0.227, P = 0.035), histological nodal stage (rs = 0.524, P < 0.001), and vascular endothelial growth factor expression (rs = 0.422; P = 0.016). Magnetic resonance imaging-based EMVI score is correlated with prognostic parameters of T3 stage rectal cancers and has the potential to become an imaging biomarker of tumor aggressiveness. Magnetic resonance imaging-based EMVI may be useful in helping the multidisciplinary team to stratify T3 rectal cancer patients for neoadjuvant therapies.
Wang, Yong; Hong, Yan; Goh, Wang Ling; Mu, Xiaojing
2016-10-01
Dual-mode Lamb-wave resonator has become a powerful component for clock reference and sensing applications, enabling efficient compensations of temperature effects, concurrent measurements of multiple environmental parameters, etc. An equivalent circuit model for the dual-mode Lamb-wave resonator is indispensable as it provides a means as well as being an effective tool for evaluating device characteristics and to aid the designing of circuitry for the resonators. This could be the first time ever that an efficient equivalent-circuit model, i.e., modified π-type Butterworth-Van Dyke model for dual-mode Lamb-wave resonators is reported. Evaluated by experiments, this model attains noteworthy agreements on both the magnitudes and phases of Y11 and Y21 of the measurement results. Compared to literature, the proposed model is capable of modeling the dual resonances efficiently. Moreover, this work also proves more accurate when viewing the Y-parameters across a wide frequency range. The gained features of this model are most beneficial for the analysis of the dual-mode Lamb-wave resonator and also for the designing of circuits.
Resonant relaxation in electroweak baryogenesis
NASA Astrophysics Data System (ADS)
Lee, Christopher; Cirigliano, Vincenzo; Ramsey-Musolf, Michael J.
2005-04-01
We compute the leading, chiral charge-changing relaxation term in the quantum transport equations that govern electroweak baryogenesis using the closed time path formulation of nonequilibrium quantum field theory. We show that the relaxation transport coefficients may be resonantly enhanced under appropriate conditions on electroweak model parameters and that such enhancements can mitigate the impact of similar enhancements in the CP-violating source terms. We also develop a power counting in the time and energy scales entering electroweak baryogenesis and include effects through second order in ratios ɛ of the small and large scales. We illustrate the implications of the resonantly enhanced O(ɛ2) terms using the Minimal Supersymmetric Standard Model, focusing on the interplay between the requirements of baryogenesis and constraints obtained from collider studies, precision electroweak data, and electric dipole moment searches.
Controlling the dipole-dipole interaction using NMR composite rf pulses
Baudin, Emmanuel
2014-08-07
New composite rf pulses are proposed during which the average dipole-dipole interactions within a spin ensemble are controlled, while a global rotation is achieved. The method used to tailor the pulses is based on the average Hamiltonian theory and relies on the geometrical properties of the spin-spin dipolar interaction. I describe several such composite pulses and analyze quantitatively the improvement brought on the control of the NMR dynamics. Numerical simulations show that the magic sandwich pulse sequence, during which the average dipolar field is effectively reversed, is plagued by defects originating from the finite initial and final π/2 rf pulses. A numerical test based on a classical description of nuclear magnetic resonance is used to check that, when these pulses are replaced by magic composite pulses, the efficiency of the magic sandwich is improved.
Magnetic Field of a Dipole and the Dipole-Dipole Interaction
ERIC Educational Resources Information Center
Kraftmakher, Yaakov
2007-01-01
With a data-acquisition system and sensors commercially available, it is easy to determine magnetic fields produced by permanent magnets and to study the dipole-dipole interaction for different separations and angular positions of the magnets. For sufficiently large distances, the results confirm the 1/R[superscript 3] law for the magnetic field…
Magnetic Field of a Dipole and the Dipole-Dipole Interaction
ERIC Educational Resources Information Center
Kraftmakher, Yaakov
2007-01-01
With a data-acquisition system and sensors commercially available, it is easy to determine magnetic fields produced by permanent magnets and to study the dipole-dipole interaction for different separations and angular positions of the magnets. For sufficiently large distances, the results confirm the 1/R[superscript 3] law for the magnetic field…
Lueken, Ulrike; Muehlhan, Markus; Evens, Ricarda; Wittchen, Hans-Ulrich; Kirschbaum, Clemens
2012-08-01
Accumulating evidence suggests that the magnetic resonance imaging (MRI) scanner can act as a stressor, eliciting subjective and neuroendocrine stress responses. Approaches to familiarize subjects with the scanner could help minimizing unintended effects on neural activation patterns of interest. Controlled studies on the effects of a scanner training are however missing. Using a comparative design, we analyzed within- and between session changes in subjective and neuroendocrine stress parameters in 63 healthy, scanner-naïve adults who participated in a two-day training protocol in an MRI, mock, or lab environment. A habituation task was used to assess within-session changes in subjective and neuroendocrine (cortisol) stress parameters; between-session changes were indicated by differences between days. MRI and mock, but not lab training were successful in reducing subjective distress towards the scanner. In contrast, cortisol reactivity towards the training environment generally increased during day 2, and the percentage of cortisol responders particularly rose in the mock and MRI groups. Within-session habituation of subjective arousal and anxiety was observed during both days and irrespective of training condition. Present findings demonstrate that training in a scanner environment successfully reduces subjective distress, but may also induce sensitization of endocrine stress levels during repeated scanning. Subjective distress can further be stabilized by acclimating subjects to the environment prior to the MRI assessment, including a short habituation phase into the assessment protocol. If replicated, present findings should be considered by researchers employing repeated measurement designs where subjects are exposed to a scanner more than once.
Lee, Mi Ji; Son, Jeong Pyo; Kim, Suk Jae; Ryoo, Sookyung; Woo, Sook-Young; Cha, Jihoon; Kim, Gyeong-Moon; Chung, Chin-Sang; Lee, Kwang Ho; Bang, Oh Young
2015-10-01
Good collateral flow is an important predictor for favorable responses to recanalization therapy and successful outcomes after acute ischemic stroke. Magnetic resonance perfusion-weighted imaging (MRP) is widely used in patients with stroke. However, it is unclear whether the perfusion parameters and thresholds would predict collateral status. The present study evaluated the relationship between hypoperfusion severity and collateral status to develop a predictive model for good collaterals using MRP parameters. Patients who were eligible for recanalization therapy that underwent both serial diffusion-weighted imaging and serial MRP were enrolled into the study. A collateral flow map derived from MRP source data was generated through automatic postprocessing. Hypoperfusion severity, presented as proportions of every 2-s Tmax strata to the entire hypoperfusion volume (Tmax≥2 s), was compared between patients with good and poor collaterals. Prediction models for good collaterals were developed with each Tmax strata proportion and cerebral blood volumes. Among 66 patients, 53 showed good collaterals based on MRP-based collateral grading. Although no difference was noted in delays within 16 s, more severe Tmax delays (Tmax16-18 s, Tmax18-22 s, Tmax22-24 s, and Tmax>24 s) were associated with poor collaterals. The probability equation model using Tmax strata proportion demonstrated high predictive power in a receiver operating characteristic analysis (area under the curve=0.9303; 95% confidence interval, 0.8682-0.9924). The probability score was negatively correlated with the volume of infarct growth (P=0.030). Collateral status is associated with more severe Tmax delays than previously defined. The present Tmax severity-weighted model can determine good collaterals and subsequent infarct growth. © 2015 American Heart Association, Inc.
A method to assess the loss of a dipole antenna for ultra-high-field MRI.
Chen, Gang; Collins, Christopher M; Sodickson, Daniel K; Wiggins, Graham C
2017-06-19
To describe a new bench measurement based on quality (Q) factors to estimate the coil noise relative to the sample noise of dipole antennas at 7 T. Placing a dipole antenna close to a highly conductive sample surrogate (HCSS) greatly reduces radiation loss, and using QHCSS gives a more accurate estimate of coil resistance than Qunloaded . Instead of using the ratio of unloaded and sample-loaded Q factors, the ratio of HCSS-loaded and sample-loaded Q factors should be used at ultra-high fields. A series of simulations were carried out to analyze the power budget of sample-loaded or HCSS-loaded dipole antennas. Two prototype dipole antennas were also constructed for bench measurements to validate the simulations. Simulations showed that radiation loss was suppressed when the dipole antenna was HCSS-loaded, and coil loss was largely the same as when the dipole was loaded by the sample. Bench measurements also showed good alignment with simulations. Using the ratio QHCSS /Qloaded gives a good estimate of the coil loss for dipole antennas at 7 T, and provides a convenient bench measurement to predict the body noise dominance of dipole antenna designs. The new approach also applies to conventional surface loop coils at ultra-high fields. Magn Reson Med 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
Stoica, Petre; Selén, Yngve; Sandgren, Niclas; Van Huffel, Sabine
2004-09-01
We introduce the knowledge-based singular value decomposition (KNOB-SVD) method for exploiting prior knowledge in magnetic resonance (MR) spectroscopy based on the SVD of the data matrix. More specifically, we assume that the MR data are well modeled by the superposition of a given number of exponentially damped sinusoidal components and that the dampings alphakappa, frequencies omegakappa, and complex amplitudes rhokappa of some components satisfy the following relations: alphakappa = alpha (alpha = unknown), omegakappa = omega + (kappa- 1)delta (omega = unknown, delta = known), and rhokappa = Ckapparho (rho = unknown, ckappa = known real constants). The adenosine triphosphate (ATP) complex, which has one triple peak and two double peaks whose dampings, frequencies, and amplitudes may in some cases be known to satisfy the above type of relations, is used as a vehicle for describing our SVD-based method throughout the paper. By means of numerical examples, we show that our method provides more accurate parameter estimates than a commonly used general-purpose SVD-based method and a previously suggested prior knowledge-based SVD method.
NASA Astrophysics Data System (ADS)
Galatà, A.; Mascali, D.; Torrisi, G.; Neri, L.; Celona, L.; Angot, J.
2017-06-01
Electron cyclotron resonance ion sources based charge breeders (ECR-CB) are fundamental devices for Isotope Separation On Line (ISOL) facilities aiming at postaccelerating radioactive ion beams (RIBs). Presently, low intensity RIBs do not allow a conventional tuning of the ECR-CB: as a consequence, it has to be set with a stable 1+ pilot beam first, switching then to the radioactive one without changing any parameter; this procedure is usually called "blind tuning." Besides having different masses, pilot and radioactive beams can also differ in terms of the rms transverse emittance ɛrms and/or longitudinal energy spread Δ E , so the choice of a given pilot beam can determine the overall performances of the final breeding stage. This paper shows a numerical study of how the capture efficiency of the PHOENIX charge breeder is affected by the aforementioned beam paramaters: the analysis reveals the two-step nature of the process, highlighting the role of the injection optics and the plasma capture capability in the overall performances of this device. The simulations predict highest efficiency for ɛrms<5 π mm mrad and Δ E <5 eV in a optimum energy range between 2 and 6 eV, thus giving important information on the possibility of blindly tuning an ECR-CB. No isotopical effects were observed, while it clearly came out the necessity to improve the 1 + beam characteristics with a rf beam cooler prior to the injection into an ECR-CB.
Hinton, J F; Fernandez, J Q; Shungu, D C; Whaley, W L; Koeppe, R E; Millett, F S
1988-01-01
Thermodynamic parameters for the binding of the monovalent cations, Li+, Na+, K+, Rb+, Cs+, NH4+, TI+, and Ag+, to gramicidin A and for the binding of TI+ to gramicidin C, incorporated into lysophosphatidylcholine, have been determined using a combination of TI-205 nuclear magnetic resonance spectroscopy and competition binding. The thermodynamic parameters, enthalpy and entropy, are discussed in terms of a process involving the transfer of cations from an aqueous to amide environment. PMID:2462930
de Torres, Juan; Mivelle, Mathieu; Moparthi, Satish Babu; Rigneault, Hervé; Van Hulst, Niek F; García-Parajó, María F; Margeat, Emmanuel; Wenger, Jérôme
2016-10-12
Förster resonance energy transfer (FRET) plays a key role in biochemistry, organic photovoltaics, and lighting sources. FRET is commonly used as a nanoruler for the short (nanometer) distance between donor and acceptor dyes, yet FRET is equally sensitive to the mutual dipole orientation. The orientation dependence complicates the FRET analysis in biological samples and may even lead to the absence of FRET for perpendicularly oriented donor and acceptor dipoles. Here, we exploit the strongly inhomogeneous and localized fields in plasmonic nanoantennas to open new energy transfer routes, overcoming the limitations from the mutual dipole orientation to ultimately enhance the FRET efficiency. We demonstrate that the simultaneous presence of perpendicular near-field components in the nanoantenna sets favorable energy transfer routes that increase the FRET efficiency up to 50% for nearly perpendicular donor and acceptor dipoles. This new facet of plasmonic nanoantennas enables dipole-dipole energy transfer that would otherwise be forbidden in a homogeneous environment. As such, our approach further increases the applicability of single-molecule FRET over diffraction-limited approaches, with the additional benefits of higher sensitivities and higher concentration ranges toward physiological levels.
Dipole Response of 76Se up to 9 MeV
NASA Astrophysics Data System (ADS)
Werner, V.; Cooper, N. M.; Goddard, P. M.; Smith, M. K.; Savran, D.; Yates, S. W.; Crider, B. P.; Peters, E. E.; Chakraborty, A.; Tonchev, A. P.; Rusev, G.; Tornow, W.; Kelley, J. H.; Kwan, E.; Raut, R.; Reichel, F.; Pietralla, N.; Romig, C.; Scheck, M.; Fritzsche, M.; Beller, J.; Zweidinger, M.; Sonnabend, K.
2013-03-01
This contribution reports on progress in the measurement of the full dipole excitation strength in 76Se.The experiments used the nuclear resonance fluorescence technique at two facilities, the photon scattering setup at the S-DALINAC at the TU Darmstadt, and the polarization setup at HIGS at TUNL. Data indicates sub-structure of the pygmy dipole resonance, and reveals a candidate for the scissors mode in 76Se. The final aim of the study is the determination of dipole strength distributions in the double-beta decay partners 76Se and 76Ge.
Back and Forth Transfer and Coherent Coupling in a Cold Rydberg Dipole Gas
Mudrich, Marcel; Zahzam, Nassim; Vogt, Thibault; Comparat, Daniel; Pillet, Pierre
2005-12-02
Coupling by the resonant dipole-dipole energy transfer between cold cesium Rydberg atoms is investigated using time-resolved narrow-band deexcitation spectroscopy. This technique combines the advantage of efficient Rydberg excitation with high-resolution spectroscopy at variable interaction times. Dipole-dipole interaction is observed spectroscopically as avoided level crossing. The coherent character of the process is linked to back and forth transfer in the np+np {r_reversible} ns+(n+1)s reaction. Decoherence in the ensemble has two different origins: the atom motion induced by dipole-dipole interaction and the migration of the s-Rydberg excitation in the environment of p-Rydberg atoms.
Multiple dipole modeling and localization from spatio-temporal MEG data
Mosher, J.C. ); Lewis, P.S. ); Leahy, R. )
1992-06-01
An array of biomagnetometers may be used to measure the spatio-temporal neuromagnetic field or magnetoencephalogram (MEG) produced by neural activity in the brain. A popular model for the neural activity produced in response to a given sensory stimulus is a set of current dipoles, where each dipole represents the primary current associated with the combined activation of a large number of neutrons located in a small volume of the brain. An important problem in the interpretation of MEG data from evoked response experiments is the localization of these neural current dipoles. The authors present here a linear algebraic framework for three common spatio-temporal dipole models: (i) unconstrained dipoles, (ii) dipoles with a fixed location, and (iii) dipoles with a fixed orientation and location. In all cases, they assume that the location, orientation, and magnitude of the dipoles are unknown. With a common model, they show how the parameter estimation problem may be decomposed into the estimation of the time invariant parameter using nonlinear least-squares minimization, followed by linear estimation of the associated time varying parameters. A subspace formulation is presented and used to derive a suboptimal least-squares subspace scanning method. The resulting algorithm is a special case of the well-known MUltiple SIgnal Classification (MUSIC) method, in which the solution (multiple dipole locations) is found by scanning potential locations using a simple one dipole model.
Second harmonic generation and enhancement in microfibers and loop resonators
NASA Astrophysics Data System (ADS)
Gouveia, Marcelo A.; Lee, Timothy; Ismaeel, Rand; Ding, Ming; Broderick, Neil G. R.; Cordeiro, Cristiano M. B.; Brambilla, Gilberto
2013-05-01
We model and experimentally investigate second harmonic generation in silica microfibers and loop resonators, in which the second order nonlinearity arises from the glass-air surface dipole and bulk multipole contributions. In the loop resonator, the recirculation of the pump light on resonance is used to increase the conversion. The effect of the loop parameters, such as coupling and loss, is theoretically studied to determine their influence on the resonance enhancement. Experimentally, microfibers were fabricated with diameters around 0.7 μm to generate the intermodally phase matched second harmonic with an efficiency up to 4.2 × 10-8 when pumped with 5 ns 1.55 μm pulses with a peak power of 90 W. After reconfiguring the microfiber into a 1 mm diameter loop, the efficiency was resonantly enhanced by 5.7 times.
Fermion dipole moment and holography
NASA Astrophysics Data System (ADS)
Kulaxizi, Manuela; Rahman, Rakibur
2015-12-01
In the background of a charged AdS black hole, we consider a Dirac particle endowed with an arbitrary magnetic dipole moment. For non-zero charge and dipole coupling of the bulk fermion, we find that the dual boundary theory can be plagued with superluminal modes. Requiring consistency of the dual CFT amounts to constraining the strength of the dipole coupling by an upper bound. We briefly discuss the implications of our results for the physics of holographic non-Fermi liquids.
Ion-dipole interactions in concentrated organic electrolytes.
Chagnes, Alexandre; Nicolis, Stamatios; Carré, Bernard; Willmann, Patrick; Lemordant, Daniel
2003-06-16
An algorithm is proposed for calculating the energy of ion-dipole interactions in concentrated organic electrolytes. The ion-dipole interactions increase with increasing salt concentration and must be taken into account when the activation energy for the conductivity is calculated. In this case, the contribution of ion-dipole interactions to the activation energy for this transport process is of the same order of magnitude as the contribution of ion-ion interactions. The ion-dipole interaction energy was calculated for a cell of eight ions, alternatingly anions and cations, placed on the vertices of an expanded cubic lattice whose parameter is related to the mean interionic distance (pseudolattice theory). The solvent dipoles were introduced randomly into the cell by assuming a randomness compacity of 0.58. The energy of the dipole assembly in the cell was minimized by using a Newton-Raphson numerical method. The dielectric field gradient around ions was taken into account by a distance parameter and a dielectric constant of epsilon = 3 at the surfaces of the ions. A fair agreement between experimental and calculated activation energy has been found for systems composed of gamma-butyrolactone (BL) as solvent and lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) as salts.
Neutron Electric Dipole Moment from Gauge-String Duality
NASA Astrophysics Data System (ADS)
Bartolini, Lorenzo; Bigazzi, Francesco; Bolognesi, Stefano; Cotrone, Aldo L.; Manenti, Andrea
2017-03-01
We compute the electric dipole moment of nucleons in the large Nc QCD model by Witten, Sakai, and Sugimoto with Nf=2 degenerate massive flavors. Baryons in the model are instantonic solitons of an effective five-dimensional action describing the whole tower of mesonic fields. We find that the dipole electromagnetic form factor of the nucleons, induced by a finite topological θ angle, exhibits complete vector meson dominance. We are able to evaluate the contribution of each vector meson to the final result—a small number of modes are relevant to obtain an accurate estimate. Extrapolating the model parameters to real QCD data, the neutron electric dipole moment is evaluated to be dn=1.8 ×10-16θ e cm . The electric dipole moment of the proton is exactly the opposite.
Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators
NASA Astrophysics Data System (ADS)
Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun
2016-07-01
The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface.
Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun
2016-07-13
The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface.
Sub-wavelength Unidirectional Antenna Realized by Stacked Spoof Localized Surface Plasmon Resonators
Qin, Feifei; Zhang, Qiang; Xiao, Jun-Jun
2016-01-01
The use of resonant structures to control scattering strength and directionality is of importance in various electromagnetic systems. Here we propose and demonstrate sub-wavelength unidirectional scattering by two nearby spoof localized surface plasmon resonators for microwave. The principle is that metal surfaces corrugated by grooves can support magnetic dipolar modes, as well as electric dipolar modes. The resonance is essentially dictated by the geometric parameter of the structure, enabling extremely high degrees of freedom for tuning the scattering properties of the resonator. Particularly, by adjusting the thickness of the resonators, we can make the magnetic dipole mode of one resonator have nearly the same resonant frequency with that of the electric dipole mode of the other resonator. We show that nearly zero backscattering happens when the distance between the two resonators is subwavelenght but larger than a certain value, otherwise strong vertical coupling and mode splitting occur. The results can be extended to other frequency bands and might find application in unique resonant devices as a radio frequency (RF) antenna, filter and metasurface. PMID:27405356
The BFKL pomeron calculus in the dipole approach
NASA Astrophysics Data System (ADS)
Kozlov, M.; Levin, E.; Prygarin, A.
2007-08-01
In this paper we continue to pursue a goal of finding an effective theory for high energy interaction in QCD based on the colour dipole approach, for which the BFKL pomeron calculus gives a low energy limit. The key problem, that we try to solve in this paper is the probabilistic interpretation of the BFKL pomeron calculus in terms of the colourless dipoles and their interactions. We demonstrate that the BFKL pomeron calculus has two equivalent descriptions: (i) one is the generating functional which gives a clear probabilistic interpretation of the processes of high energy scattering and also provides a Hamiltonian-like description of the system of interacting dipoles; (ii) the second is the Langevin equation with a specific noise term which is rather complicated. We found that at high energies this Langevin equation can be reduced to the Langevin equation for directed percolation in the momentum space if the impact parameter is large, namely, b≫1/k, where k is the transverse momentum of a dipole. Unfortunately, this simplified form of Langevin equation is not applicable for summation of pomeron loops, where one integrates over all possible values of impact parameter. We show that the BFKL pomeron calculus with two vertices (splitting P→P+P and merging P+P→P of pomerons) can be interpreted as a system of colourless dipoles with two processes: the decay of one dipole into two and the merging of two dipoles into one dipole. However, a number of assumptions we have to make on the way to simplify the noise term in the Langevin equation and/or to apply the probabilistic interpretation, therefore, we can consider both of these approaches in the present form only as the QCD motivated models.
Deng, Haishan; Xie, Shaofei; Xiang, Bingren; Zhan, Ying; Li, Wei; Li, Xiaohua; Jiang, Caiyun; Wu, Xiaohong; Liu, Dan
2014-01-01
Simultaneous determination of multiple weak chromatographic peaks via stochastic resonance algorithm attracts much attention in recent years. However, the optimization of the parameters is complicated and time consuming, although the single-well potential stochastic resonance algorithm (SSRA) has already reduced the number of parameters to only one and simplified the process significantly. Even worse, it is often difficult to keep amplified peaks with beautiful peak shape. Therefore, multiobjective genetic algorithm was employed to optimize the parameter of SSRA for multiple optimization objectives (i.e., S/N and peak shape) and multiple chromatographic peaks. The applicability of the proposed method was evaluated with an experimental data set of Sudan dyes, and the results showed an excellent quantitative relationship between different concentrations and responses.
Schroeter, Aileen; Grandjean, Joanes; Schlegel, Felix; Saab, Bechara J; Rudin, Markus
2016-01-01
Previously, we reported widespread bilateral increases in stimulus-evoked functional magnetic resonance imaging signals in mouse brain to unilateral sensory paw stimulation. We attributed the pattern to arousal-related cardiovascular changes overruling cerebral autoregulation thereby masking specific signal changes elicited by local neuronal activity. To rule out the possibility that interhemispheric neuronal communication might contribute to bilateral functional magnetic resonance imaging responses, we compared stimulus-evoked functional magnetic resonance imaging responses to unilateral hindpaw stimulation in acallosal I/LnJ, C57BL/6, and BALB/c mice. We found bilateral blood-oxygenation-level dependent signal changes in all three strains, ruling out a dominant contribution of transcallosal communication as reason for bilaterality. Analysis of functional connectivity derived from resting-state functional magnetic resonance imaging, revealed that bilateral cortical functional connectivity is largely abolished in I/LnJ animals. Cortical functional connectivity in all strains correlated with structural connectivity in corpus callosum as revealed by diffusion tensor imaging. Given the profound influence of systemic hemodynamics on stimulus-evoked functional magnetic resonance imaging outcomes, we evaluated whether functional connectivity data might be affected by cerebrovascular parameters, i.e. baseline cerebral blood volume, vascular reactivity, and reserve. We found that effects of cerebral hemodynamics on functional connectivity are largely outweighed by dominating contributions of structural connectivity. In contrast, contributions of transcallosal interhemispheric communication to the occurrence of ipsilateral functional magnetic resonance imaging response of equal amplitude to unilateral stimuli seem negligible.
Subwavelength resonant antennas enhancing electromagnetic energy harvesting
NASA Astrophysics Data System (ADS)
Oumbe Tekam, Gabin; Ginis, Vincent; Seetharamdoo, Divitha; Danckaert, Jan
2016-04-01
In this work, an electromagnetic energy harvester operating at microwave frequencies is designed based on a cut- wire metasurface. This metamaterial is known to contain a quasistatic electric dipole resonator leading to a strong resonant electric response when illuminated by electromagnetic fields.1 Starting from an equivalent electrical circuit, we analytically design the parameters of the system to tune the resonance frequency of the harvester at the desired frequency band. Subsequently, we compare these results with numerical simulations, which have been obtained using finite elements numerical simulations. Finally, we optimize the design by investigating the best arrangement for energy harvesting by coupling in parallel and in series many single layers of cut-wire metasurfaces. We also discuss the implementation of different geometries and sizes of the cut-wire metasurface for achieving different center frequencies and bandwidths.
Kato, Yushi; Sakamoto, Naoki; Kiriyama, Ryutaro; Takenaka, Tomoya; Kurisu, Yosuke; Nozaki, Dai; Sato, Fuminobu; Iida, Toshiyuki
2012-02-01
In order to contribute to various applications of plasma and beams based on an electron cyclotron resonance, a new concept on magnetic field with all magnets on plasma production and confinement has been proposed with enhanced efficiency for broad and dense ion beam. The magnetic field configuration consists of a pair of comb-shaped magnet surrounding plasma chamber cylindrically. Resonance zones corresponding for 2.45 GHz and 11-13 GHz frequencies are positioned at spatially different positions. We launch simultaneously multiplex frequencies microwaves operated individually, try to control profiles of the plasma parameters and the extracted ion beams, and to measure them in detail.
Kato, Yushi; Sakamoto, Naoki; Kiriyama, Ryutaro; Takenaka, Tomoya; Kurisu, Yosuke; Nozaki, Dai; Sato, Fuminobu; Iida, Toshiyuki
2012-02-15
In order to contribute to various applications of plasma and beams based on an electron cyclotron resonance, a new concept on magnetic field with all magnets on plasma production and confinement has been proposed with enhanced efficiency for broad and dense ion beam. The magnetic field configuration consists of a pair of comb-shaped magnet surrounding plasma chamber cylindrically. Resonance zones corresponding for 2.45 GHz and 11-13 GHz frequencies are positioned at spatially different positions. We launch simultaneously multiplex frequencies microwaves operated individually, try to control profiles of the plasma parameters and the extracted ion beams, and to measure them in detail.
Measuring the Forces between Magnetic Dipoles
ERIC Educational Resources Information Center
Gayetsky, Lisa E.; Caylor, Craig L.
2007-01-01
We describe a simple undergraduate lab in which students determine how the force between two magnetic dipoles depends on their separation. We consider the case where both dipoles are permanent and the case where one of the dipoles is induced by the field of the other (permanent) dipole. Agreement with theoretically expected results is quite good.
A new Skyrme energy density functional for a better description of spin-isospin resonances
NASA Astrophysics Data System (ADS)
Roca-Maza, X.; Colò, G.; Cao, Li-Gang; Sagawa, H.
2015-10-01
A correct determination of the isospin and spin-isospin properties of the nuclear effective interaction should lead to an accurate description of the Gamow-Teller resonance (GT), the Spin Dipole Resonance (SDR), the Giant Dipole Resonance (GDR) or the Antianalog Giant Dipole Resonance (AGDR), among others. A new Skyrme energy density functional named SAMi is introduced with the aim of going a step forward in setting the bases for a more precise description of spin-isospin resonances [1, 2]. In addition, we will discuss some new features of our analysis on the AGDR in 208Pb [3] as compared with available experimental data on this resonance [4, 5, 6], and on the GDR [7]. Such study, guided by a simple yet physical pocket formula, has been developed by employing the so called SAMi-J family of systematically varied interactions. This set of interactions is compatible with experimental data for values of the symmetry energy at saturation J and slope parameter L falling in the ranges 31-33 MeV and 75-95 MeV, respectively.
A new Skyrme energy density functional for a better description of spin-isospin resonances
Roca-Maza, X.; Colò, G.; Cao, Li-Gang; Sagawa, H.
2015-10-15
A correct determination of the isospin and spin-isospin properties of the nuclear effective interaction should lead to an accurate description of the Gamow-Teller resonance (GT), the Spin Dipole Resonance (SDR), the Giant Dipole Resonance (GDR) or the Antianalog Giant Dipole Resonance (AGDR), among others. A new Skyrme energy density functional named SAMi is introduced with the aim of going a step forward in setting the bases for a more precise description of spin-isospin resonances [1, 2]. In addition, we will discuss some new features of our analysis on the AGDR in {sup 208}Pb [3] as compared with available experimental data on this resonance [4, 5, 6], and on the GDR [7]. Such study, guided by a simple yet physical pocket formula, has been developed by employing the so called SAMi-J family of systematically varied interactions. This set of interactions is compatible with experimental data for values of the symmetry energy at saturation J and slope parameter L falling in the ranges 31−33 MeV and 75−95 MeV, respectively.
Development of plasma sources for Dipole Research EXperiment (DREX)
NASA Astrophysics Data System (ADS)
Xiao, Qingmei; Wang, Zhibin; Peng, E.; Wang, Xiaogang; Xiao, Chijie; Ren, Yang; Ji, Hantao; Mao, Aohua; Li, Liyi
2017-05-01
Dipole Research EXperiment (DREX) is a new terrella device as part of the Space Plasma Environment Research Facility (SPERF) for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance (ECR) system for the ‘whistler/chorus’ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén’ wave study. The parameters of ‘whistler/chorus’ waves and ‘Alfvén’ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt’ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.
[Dipole tracing of visual evoked potentials in human brain].
Shevelev, I A; Mikhaĭlova, E S; Kulikov, M A; Slavutskaia, A V
2008-01-01
3D tracing of equivalent current dipoles (ECDs) of averaged human visual evoked potentials (VEP) by their distribution across a 34-electrode array was obtained under short presentation of pattern-onset stimuli (sets of 45 horizontal, vertical bars or crosses). Using a 2-dipole spherical three-layer model, we dynamically (step of 1 ms) localized dipoles in four healthy subjects. Dipole locations were matched to anatomical brain regions visualized in structural MRI. Best-fitting source parameters were superimposed on MR images of each subject to identify the anatomical structures giving rise to the surface patterns. It was found that during 50-300 ms following the onset of the stimuli, the ECDs in all subjects were localized in the occipital cortex and demonstrated reliable systematic shift in localization. Two local (1-2 cm3) zones of the preferable dipole attendance were found at 5-6 cm behind zero line: the first one was localized near the midline of the brain, whereas the other zone was situated in the right hemisphere at a distance of 6-7 cm from the first zone. Their localization and strength of activation were reliably different for crosses and lines and changed during VEP generation. Zones of relatively rare dipole attendance were found also. The data are discussed in relation to localization of initial and endpoint of ECDs trajectories, as well as with sensitivity of the visual cortex to line crossing and branching.
NASA Astrophysics Data System (ADS)
Dzhilavyan, L. Z.; Lapik, A. M.; Nedorezov, V. G.; Tulupov, B. A.
2017-01-01
A brief overview of the methods for separating the contributions of isovector electric quadrupole ( E2) and dominant dipole ( E1) giant resonances in atomic nuclei, which are excited in direct and inverse reactions with photons (real and virtual), is given. The basic parameters of isovector giant resonance E2, which were declared to date by applying some of these methods to the results with 208Pb, are also presented.
Energy of van der Waals and dipole-dipole interactions between atoms in Rydberg states
NASA Astrophysics Data System (ADS)
Kamenski, A. A.; Manakov, N. L.; Mokhnenko, S. N.; Ovsiannikov, V. D.
2017-09-01
The van der Waals coefficient C6(θ ;n l J M ) of two like Rydberg atoms in their identical Rydberg states |n l J M 〉 is resolved into four irreducible components called scalar Rs s, axial (vector) Ra a, scalar-tensor Rs T=RT s , and tensor-tensor RT T parts in analogy with the components of dipole polarizabilities. The irreducible components determine the dependence of C6(θ ;n l J M ) on the angle θ between the interatomic and the quantization axes of atoms. The spectral resolution for the biatomic Green's function with account of the most contributing terms is used for evaluating the components Rα β of atoms in their Rydberg series of doublet states of the low angular momenta (2S , 2P , 2D , 2F ). The polynomial presentations in powers of the Rydberg-state principal quantum number n taking into account the asymptotic dependence C6(θ ;n l J M ) ∝n11 are derived for simplified evaluations of irreducible components. Numerical values of the polynomial coefficients are determined for Rb atoms in their n 2S1 /2 , n 2P1 /2 ,3 /2 , n 2D3 /2 ,5 /2 , and n 2F5 /2 ,7 /2 Rydberg states of arbitrary high n . The transformation of the van der Waals interaction law -C6/R6 into the dipole-dipole law C3/R3 in the case of close dipole-connected two-atomic states (the Förster resonance) is considered and the dependencies on the magnetic quantum numbers M and on the angle θ of the constant C3(θ ;n l J M ) are determined together with the ranges of interatomic distances R , where the transformation appears.
Gap-plasmon nanoantennas and bowtie resonators
NASA Astrophysics Data System (ADS)
Gramotnev, Dmitri K.; Pors, Anders; Willatzen, Morten; Bozhevolnyi, Sergey I.
2012-01-01
Plasmonic bowtie resonators involving gap surface plasmons (GSPs) in metal-insulator-metal (MIM) structures, in which only the top metal layer is structured, are investigated using numerical simulations. We demonstrate that the considered configuration features two efficiently excitable GSP resonances associated with distinct charge distributions with the domination of the dipole and quadrupole moments resulting in low- and high-Q resonances, respectively. The typical Q factors for the high-Q resonances are shown to achieve ˜25 in the near-infrared, thus potentially exceeding the quasistatic limit. Detailed physical interpretations of the obtained results and consistent dependencies of the resonance characteristics on the geometrical structural parameters are presented. Excellent resonant characteristics, the simplicity of fabrication, and tuning of the resonance wavelength by adjusting the size of the bowtie arms, separation between them, and/or thickness of the insulator (SiO2) layer in the MIM structure appear attractive for a wide variety of applications, ranging from surface sensing to photovoltaics.
Sumachev, V. V.; Beloglazov, Yu. A.; Filimonov, E. A.; Kovalev, A. I.; Kozlenko, N. G.; Kruglov, S. P.; Kulbardis, A. A.; Lopatin, I. V.; Novinsky, D. V.; Shchedrov, V. A.; Trautman, V. Yu.; Alekseev, I. G.; Budkovsky, P. E.; Kanavets, V. P.; Koroleva, L. I.; Morozov, B. V.; Nesterov, V. M.; Ryltsov, V. V.; Sulimov, A. D.; Svirida, D. N.
2008-10-13
The existing models of baryons usually predict considerably more resonance (three or more in number) than it was found by investigation of elastic pion-nucleon scattering. This disagreement invites further investigation of the pion-nucleon interaction and among other things the measurement of spin rotation parameters A and R in the elastic pion-nucleon scattering.Recent experiments of the PNPI and PNPI-ITEP collaborations resolved a part of twofold ambiguities of the existing partial wave analyses (PWA). These results were used in the last PWA of the George Washington University group SP06. The proposal for the additional spin rotation parameters A and R measurement in the resonance region is motivated. Such additional measurements are necessary to resolve remaining twofold ambiguities of the existing PWAs.
On the dipole polarisability and dipole sum rules of ozone
NASA Astrophysics Data System (ADS)
Kalugina, Yulia N.; Thakkar, Ajit J.
2015-10-01
Ab initio calculations of the dipole polarisability and other Cauchy moments of the dipole oscillator strength distribution (DOSD) of ozone are reported to help resolve discrepancies between theory and experiment. A number of coupled-cluster methods based on a Hartree-Fock reference function, multiconfiguration-reference configuration interaction methods, and perturbatively corrected, complete-active-space self-consistent field methods are used. The C DOSD of Kumar and Thakkar is probably preferable to their B1 distribution. Our best estimate of the mean polarisability is ? atomic units.
NASA Astrophysics Data System (ADS)
Marante, Carlos; Klinker, Markus; Kjellsson, Tor; Lindroth, Eva; González-Vázquez, Jesús; Argenti, Luca; Martín, Fernando
2017-08-01
The XCHEM approach interfaces well established quantum chemistry packages with scattering numerical methods in order to describe single-ionization processes in atoms and molecules. This should allow one to describe electron correlation in the continuum at the same level of accuracy as quantum chemistry methods do for bound states. Here we have applied this method to study multichannel photoionization of Ne in the vicinity of the autoionizing states lying between the 2 s22 p5 and 2 s 2 p6 ionization thresholds. The calculated total photoionization cross sections are in very good agreement with the absolute measurement of Samson et al. [J. Electron Spectrosc. Relat. Phenom. 123, 265 (2002), 10.1016/S0368-2048(02)00026-9], and with independent benchmark calculations performed at the same level of theory. From these cross sections, we have extracted resonance positions, total autoionization widths, Fano profile parameters, and correlation parameters for the lowest three autoionizing states. The values of these parameters are in good agreement with those reported in earlier theoretical and experimental work. We have also evaluated β asymmetry parameter and partial photoionization cross sections and, from the latter, partial autoionization widths and Starace parameters for the same resonances, not yet available in the literature. Resonant features in the calculated β parameter are in good agreement with the experimental observations. We have found that the three lowest resonances preferentially decay into the 2 p-1ɛ d continuum rather than into the 2 p-1ɛ s one [Phys. Rev. A 89, 043415 (2014), 10.1103/PhysRevA.89.043415], in agreement with previous expectations, and that in the vicinity of the resonances the partial 2 p-1ɛ s cross section can be larger than the 2 p-1ɛ d one, in contrast with the accepted idea that the latter should amply dominate in the whole energy range. These results show the potential of the XCHEM approach to describe highly correlated process
SEMERTZIDIS, Y.K.
2005-05-23
We have shown that the study of dipole moments, both magnetic and electric, in storage rings offer unique opportunities in probing physics beyond the Standard Model (SM). Both methods use similar techniques (particle and spin precession in magnetic storage rings). We are currently investigating the systematic errors associated with the resonance electric dipole moment (EDM) method. So far it looks very promising.
Complete dipole response in {sup 208}Pb from high-resolution polarized proton scattering at 0 deg
Neumann-Cosel, P. von; Kalmykov, Y.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Adachi, T.; Fujita, Y.; Matsubara, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Bertulani, C. A.; Carter, J.; Fujita, H.; Dozono, M.; Fujita, K.; Hashimoto, H.; Hatanaka, K.
2009-01-28
The structure of electric and magnetic dipole modes in {sup 208}Pb is investigated in a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg. First results on the E1 strength in the region of the pygmy dipole resonance are reported.
Role of dipole elongation in orientationally ordered liquids
NASA Astrophysics Data System (ADS)
Wei, Dong-Qing; Gao, Lin; Zhang, Jiao; Yan, Li-Wei; Hu, Jin-He; Chen, Lang; Gong, Zi-Zheng; Guo, Yong-Xin; Han, Yu
2011-06-01
A recent study shows that the dipole elongation in the extended dipole model plays a significant role in the phase transitions of liquid crystal phases. In this paper, molecular dynamics (MD) simulations were performed for the dipole model with different distances between the two charges keeping the total dipole moment the same. The potential energy consists of the Lennard-Jones potential and the site-site electrostatic contribution of partial charges. Detailed analyses were made with respect to the average order parameters
A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER)
NASA Astrophysics Data System (ADS)
Garbacz, Piotr; Fischer, Peer; Krämer, Steffen
2016-09-01
Direct detection of molecular chirality is practically impossible by methods of standard nuclear magnetic resonance (NMR) that is based on interactions involving magnetic-dipole and magnetic-field operators. However, theoretical studies provide a possible direct probe of chirality by exploiting an enantiomer selective additional coupling involving magnetic-dipole, magnetic-field, and electric field operators. This offers a way for direct experimental detection of chirality by nuclear magneto-electric resonance (NMER). This method uses both resonant magnetic and electric radiofrequency (RF) fields. The weakness of the chiral interaction though requires a large electric RF field and a small transverse RF magnetic field over the sample volume, which is a non-trivial constraint. In this study, we present a detailed study of the NMER concept and a possible experimental realization based on a loop-gap resonator. For this original device, the basic principle and numerical studies as well as fabrication and measurements of the frequency dependence of the scattering parameter are reported. By simulating the NMER spin dynamics for our device and taking the 19F NMER signal of enantiomer-pure 1,1,1-trifluoropropan-2-ol, we predict a chirality induced NMER signal that accounts for 1%-5% of the standard achiral NMR signal.
A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER).
Garbacz, Piotr; Fischer, Peer; Krämer, Steffen
2016-09-14
Direct detection of molecular chirality is practically impossible by methods of standard nuclear magnetic resonance (NMR) that is based on interactions involving magnetic-dipole and magnetic-field operators. However, theoretical studies provide a possible direct probe of chirality by exploiting an enantiomer selective additional coupling involving magnetic-dipole, magnetic-field, and electric field operators. This offers a way for direct experimental detection of chirality by nuclear magneto-electric resonance (NMER). This method uses both resonant magnetic and electric radiofrequency (RF) fields. The weakness of the chiral interaction though requires a large electric RF field and a small transverse RF magnetic field over the sample volume, which is a non-trivial constraint. In this study, we present a detailed study of the NMER concept and a possible experimental realization based on a loop-gap resonator. For this original device, the basic principle and numerical studies as well as fabrication and measurements of the frequency dependence of the scattering parameter are reported. By simulating the NMER spin dynamics for our device and taking the (19)F NMER signal of enantiomer-pure 1,1,1-trifluoropropan-2-ol, we predict a chirality induced NMER signal that accounts for 1%-5% of the standard achiral NMR signal.
Remote Sensing of Dipole Rings
NASA Technical Reports Server (NTRS)
Hooker, Stanford B.; Mied, Richard P.; Brown, James W.; Kirwan, A. D., Jr.
1997-01-01
Historical satellite-derived sea surface temperature (SST) data are reanalyzed with a zebra color palette and a thermal separatrix method. The new results from this reanalysis are as follows: (a) Thirteen observational sequences of six rings from the Gulf Stream and the Brazil Current, which have historically been interpreted as solitary vortices or monopoles are shown to have a dipolar character; (b) some of these dipole rings have been observed in the open ocean, thereby eliminating the possibility that they are sustained by topographic interactions with the continental slope; (c) whether interacting with other features or evolving as isolated circulations, dipoles are seen to rotate within a relatively narrow range of approximately 4-8 deg/day (interacting) and 10-11 deg/day (isolated); and (d) feature tracking delineates energetic fluid in both vortices and eliminates the possibility of interpreting dipole rings as transient features produced by active monopoles and patches of entrained fluid.
11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades
Zlobin, A. V.; Andreev, N.; Apollinari, G.; Auchmann, B.; Barzi, E.; Izquierdo Bermudez, S.; Bossert, R.; Buehler, M.; Chlachidze, G.; DiMarco, J.; Karppinen, M.; Nobrega, F.; Novitski, I.; Rossi, L.; Smekens, D.; Tartaglia, M.; Turrioni, D.; Velev, Genadi
2015-01-01
FNAL and CERN are developing a twin-aperture 11 T Nb3Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.
NASA Astrophysics Data System (ADS)
Deepa, H. R.; Thipperudrappa, J.; Suresh Kumar, H. M.
2013-05-01
The absorption and fluorescence spectra of 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoro methyl)-2H-pyrano[2,3-b][1,8]naphthyridin-2-one (LD-489) and 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) have been recorded at room temperature in different solvents and 1,4-dioxane-acetonitrile solvent mixtures. The UV-Visible absorption spectra are less sensitive to solvent polarity than the corresponding fluorescence spectra in both the dyes which show pronounced solvatochromic effect. The effects of solvents upon the spectral properties are analyzed using Lippert-Mataga polarity function, Richardts microscopic solvent polarity parameter and Catalán's multiple linear regression approach. Both general solute-solvent interactions and specific interactions are operative in these systems. The solvatochromic correlations are used to estimate excited state dipole moments using experimentally determined ground state dipole moments. The excited state dipole moment for both the dyes are found to be larger than their corresponding ground state dipole moment and is interpreted based on their resonance structures.
Analyzing Feshbach resonances: A Li6-Cs133 case study
NASA Astrophysics Data System (ADS)
Pires, R.; Repp, M.; Ulmanis, J.; Kuhnle, E. D.; Weidemüller, M.; Tiecke, T. G.; Greene, Chris H.; Ruzic, Brandon P.; Bohn, John L.; Tiemann, E.
2014-07-01
We provide a comprehensive comparison of a coupled channel calculation, the asymptotic bound-state model (ABM), and the multichannel quantum defect theory (MQDT). Quantitative results for 6Li-133Csare presented and compared to previously measured 6Li-133CsFeshbach resonances (FRs) [Repp et al., Phys. Rev. A 87, 010701(R) (2013), 10.1103/PhysRevA.87.010701]. We demonstrate how the accuracy of the ABM can be stepwise improved by including magnetic dipole-dipole interactions and coupling to a nondominant virtual state. We present a MQDT calculation, where magnetic dipole-dipole and second-order spin-orbit interactions are included. A frame transformation formalism is introduced, which allows the assignment of measured FRs with only three parameters. All three models achieve a total rms error of <1G on the observed FRs. We critically compare the different models in view of the accuracy for the description of FRs and the required input parameters for the calculations.
Mesoscopic supersolid of dipoles in a trap
Golomedov, A. E.; Astrakharchik, G. E.; Lozovik, Yu. E.
2011-09-15
A mesoscopic system of dipolar bosons trapped by a harmonic potential is considered. The system has a number of physical realizations including dipole excitons, atoms with large dipolar moment, polar molecules, and Rydberg atoms in inhomogeneous electric field. We carry out a diffusion Monte Carlo simulation to define the quantum properties of a two-dimensional system of trapped dipoles at zero temperature. In dimensionless units the system is described by two control parameters, namely, the number of particles and the strength of the interparticle interaction. We have shown that when the interparticle interaction is strong enough a mesoscopic crystal is formed. As the strength of interactions is decreased a multistage melting takes place. Off-diagonal order in the system is tested using natural-orbitals analysis. We have found that the system might be Bose condensed even in the case of strong interparticle interactions. There is a set of parameters for which a spatially ordered structure is formed while simultaneously the fraction of Bose-condensed particles is nonzero. This might be considered as a realization of a mesoscopic supersolid.
Dipole Field Effects on Ion Ejections from a Paul Ion Trap
NASA Technical Reports Server (NTRS)
MacAskill, J. A.; Chutjian, A.
2011-01-01
Attempts at improving the quality of mass spectra obtained from a Paul trap mass spectrometer prompted an investigation of the effects of additional fields to supplement the primary rf quadrupole trapping field. Reported here are the results of the first in a series of tests that focuses on the application of a single dipole field to augment the trapping and subsequent ejections of ions stored within a Paul trap. Measurements are presented for a fixed quadrupole frequency with varying dipole frequencies. The presence of the dipole field during the quadrupole trapping phase causes ion ejections of single m/z species at discrete dipole frequencies. During the mass analysis phase, the varying dipole frequency produces a complex set of resonant structures that impact ejection time (mass range), as well as mass spectral peak intensity and width
NASA Astrophysics Data System (ADS)
Kandidov, V. P.; Terekhova, Irina V.
2003-06-01
A technique for phase filtering of the inphase collective mode of a laser array in the Talbot resonator is developed. This technique is based on the formation of the phase distribution of the inphase mode field of the linear array with the finite number of channels close to that of the field of the infinite periodic structure. A simple scheme of the phase corrector, providing the increase in the selectivity of the inphase mode of the laser array in the Talbot resonator, is proposed. It is shown that the width of the principal maximum of the far-field intensity does not increase during the phase filtering.
Paths to Förster's resonance energy transfer (FRET) theory
NASA Astrophysics Data System (ADS)
Masters, B. R.
2014-02-01
Theodor Förster (1910-1974) developed a phenomenological theory of nonradiative resonance energy transfer which proved to be transformative in the fields of chemistry, biochemistry, and biology. This paper explores the experimental and the theoretical antecedents of Förster's theory of resonance energy transfer (FRET). Early studies of sensitized fluorescence, fluorescence depolarization, and photosynthesis demonstrated the phenomena of long-range energy transfer. At the same time physicists developed theoretical models which contained common physical mechanisms and parameters: oscillating dipoles as models for the atoms or molecules, dipole-dipole coupling for the interaction, and a distance R0 that is optimal for resonance energy transfer. Early theories predicted R0 that was too large as compared to experiments. Finally, in 1946 Förster developed a classical theory and in 1948 he developed a quantum mechanical theory; both theories predicted an inverse sixth power dependence of the rate of energy transfer and a R0 that agreed with experiments. This paper attempts to determine why Förster succeeded when the other theoreticians failed to develop the correct theory. The putative roles of interdisciplinary education and collaborative research are discussed. Furthermore, I explore the role of science journals and their specific audiences in the popularization of FRET to a broad interdisciplinary community.
Coherent and incoherent dipole-dipole interactions between atoms
NASA Astrophysics Data System (ADS)
Robicheaux, Francis
2016-05-01
Results will be presented on the collective interaction between atoms due to the electric dipole-dipole coupling between states of different parity on two different atoms. A canonical example of this effect is when the electronic state of one atom has S-character and the state of another atom has P-character. The energy difference between the two states plays an important role in the interaction since the change in energy determines the wave number of a photon that would cause a transition between the states. If the atoms are much closer than the wave length of this photon, then the dipole-dipole interaction is in the near field and has a 1 /r3 dependence on atomic separation. If the atoms are farther apart than the wave length, then the interaction is in the far field and has a 1 / r dependence. When many atoms interact, collective effects can dominate the system with the character of the collective effect depending on whether the atomic separation leads to near field or far field coupling. As an example of the case where the atoms are in the far field, the line broadening of transitions and strong deviations from the Beer-Lambert law in a diffuse gas will be presented. As an example of near field collective behavior, the radiative properties of a Rydberg gas will be presented. Based upon work supported by the National Science Foundation under Grant No. 1404419-PHY in collaboration with R.T. Sutherland.
Dodonov, V. V.
2010-10-15
The Mueller-Bethe-Schwinger-Casimir formulas for the frequency shift in electromagnetic resonators are generalized to the case of big variations of electric permittivity inside small regions. These formulas are important, in particular, for the studies of the dynamical Casimir effect.
Yesinowski, James P; Ladouceur, Harold D; Purdy, Andrew P; Miller, Joel B
2010-12-21
We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves (63)Cu, (65)Cu, and (127)I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu(+)-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the (207)Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu(+) vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the (63)Cu and (127)I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for (63)Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by
NASA Astrophysics Data System (ADS)
Yesinowski, James P.; Ladouceur, Harold D.; Purdy, Andrew P.; Miller, Joel B.
2010-12-01
We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of γ-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the 207Pb resonance of lead nitrate mixed with the γ-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu+ vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the 63Cu and 127I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for 63Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by rotating a
Low-frequency RF Coupling To Unconventional (Fat Unbalanced) Dipoles
Ong, M M; Brown, C G; Perkins, M P; Speer, R D; Javedani, J B
2010-12-07
The report explains radio frequency (RF) coupling to unconventional dipole antennas. Normal dipoles have thin equal length arms that operate at maximum efficiency around resonance frequencies. In some applications like high-explosive (HE) safety analysis, structures similar to dipoles with ''fat'' unequal length arms must be evaluated for indirect-lightning effects. An example is shown where a metal drum-shaped container with HE forms one arm and the detonator cable acts as the other. Even if the HE is in a facility converted into a ''Faraday cage'', a lightning strike to the facility could still produce electric fields inside. The detonator cable concentrates the electric field and carries the energy into the detonator, potentially creating a hazard. This electromagnetic (EM) field coupling of lightning energy is the indirect effect of a lightning strike. In practice, ''Faraday cages'' are formed by the rebar of the concrete facilities. The individual rebar rods in the roof, walls and floor are normally electrically connected because of the construction technique of using metal wire to tie the pieces together. There are two additional requirements for a good cage. (1) The roof-wall joint and the wall-floor joint must be electrically attached. (2) All metallic penetrations into the facility must also be electrically connected to the rebar. In this report, it is assumed that these conditions have been met, and there is no arcing in the facility structure. Many types of detonators have metal ''cups'' that contain the explosives and thin electrical initiating wires, called bridge wires mounted between two pins. The pins are connected to the detonator cable. The area of concern is between the pins supporting the bridge wire and the metal cup forming the outside of the detonator. Detonator cables usually have two wires, and in this example, both wires generated the same voltage at the detonator bridge wire. This is called the common-mode voltage. The explosive component
Dipole response of neutron-rich Sn isotopes
NASA Astrophysics Data System (ADS)
Klimkiewicz, A.; Adrich, P.; Boretzky, K.; Fallot, M.; Aumann, T.; Cortina-Gil, D.; Datta Pramanik, U.; Elze, Th. W.; Emling, H.; Geissel, H.; Hellstroem, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Leifels, Y.; Nociforo, C.; Palit, R.; Simon, H.; Surowka, G.; Sümmerer, K.; Typel, S.; Walus, W.
2007-05-01
The neutron-rich isotopes 129-133Sn were studied in a Coulomb excitation experiment at about 500 AMeV using the FRS-LAND setup at GSI. From the exclusive measurement of all projectile-like particles following the excitation and decay of the projectile in a high-Z target, the energy differential cross section can be extracted. At these beam energies dipole transitions are dominating, and within the semi-classical approach the Coulomb excitation cross sections can be transformed into photoabsorption cross sections. In contrast to stable Sn nuclei, a substantial fraction of dipole strength is observed at energies below the giant dipole resonance (GDR). For 130Sn and 132Sn this strength is located in a peak-like structure around 10 MeV excitation energy and exhibits a few percent of the Thomas-Reiche Kuhn (TRK) sum-rule strength. Several calculations predict the appearance of dipole strength at low excitation energies in neutron-rich nuclei. This low-lying strength is often referred to as pygmy dipole resonance (PDR) and, in a macroscopic picture, is discussed in terms of a collective oscillation of excess neutrons versus the core nucleons. Moreover, a sharp rise is observed at the neutron separation threshold around 5 MeV for the odd isotopes. A possible contribution of 'threshold strength', which can be described within the direct-breakup model is discussed. The results for the neutron-rich Sn isotopes are confronted with results on stable nuclei investigated in experiments using real photons.
NASA Astrophysics Data System (ADS)
Zhuromskyy, O.; Peschel, U.
2014-09-01
Lossless propagation of longitudinal magnetic dipole waves along chains of high-index subwavelength particles is predicted for a narrow frequency range around the magnetic Mie resonance of the individual particles. Mathematical analogies between dipole and magnetoinductive waves are used to reduce back-reflections thus improving the power transfer efficiency of respective particle waveguides. The proposed technique can be used to optimize the propagation of even more complex particle-based configurations.
Induced dipole-dipole interactions in light diffusion from point dipoles
NASA Astrophysics Data System (ADS)
Cherroret, Nicolas; Delande, Dominique; van Tiggelen, Bart A.
2016-07-01
We develop a perturbative treatment of induced dipole-dipole interactions in the diffusive transport of electromagnetic waves through disordered atomic clouds. The approach is exact at order 2 in the atomic density and accounts for the vector character of light. It is applied to the calculations of the electromagnetic energy stored in the atomic cloud, which modifies the energy transport velocity, and of the light scattering and transport mean free paths. Results are compared to those obtained from a purely scalar model for light.
Dipole polarizabilities of charged pions
NASA Astrophysics Data System (ADS)
Fil'kov, L. V.; Kashevarov, V. L.
2017-01-01
We discuss main experimental works, where dipole polarizabilities of charged pions have been determined. Possible reasons for the differences between the experimental data are discussed. In particular, it is shown that the account of the -meson gives a significant correction to the value of the polarizability obtained in the latest experiment of the COMPASS collaboration.
NASA Astrophysics Data System (ADS)
Schildknecht, Dieter
2017-03-01
We give a brief representation of the theoretical results from the color dipole picture, covering the total photoabsorption cross section, high-energy J/ψ photoproduction with respect to recent experimental data from the LHCb Collaboration at CERN, and ultra-high energy neutrino scattering, relevant for the ICE-CUBE experiment.
Garcia-Ripoll; Perez-Garcia; Ostrovskaya; Kivshar
2000-07-03
We find a new type of optical vector soliton that originates from trapping of a dipole mode by the soliton-induced waveguides. These solitons, which appear as a consequence of the vector nature of the two-component system, are more stable than the previously found optical vortex solitons and represent a new type of extremely robust nonlinear vector structure.
All-dielectric hollow nanodisk for tailoring magnetic dipole emission.
Feng, Tianhua; Xu, Yi; Liang, Zixian; Zhang, Wei
2016-11-01
We propose a silicon hollow nanodisk for enhancing magnetic dipole (MD) emission. The Purcell factor can be more than 300, which is one order of magnitude larger than the silicon nanosphere case. It is demonstrated that the silicon hollow nanodisk resembles the function of an azimuthally polarized beam for tailoring the magnetic and electric dipole (ED) emission. It is shown that MD emission can be significantly enhanced, while ED emission will be suppressed when emitters are located in the hollow of the nanodisk. The dependence of the Purcell factor on the geometry parameters is also studied. Our results might facilitate the on-chip engineering of magnetic light emission.
Multiple Magnetic Dipole Modeling Coupled with a Genetic Algorithm
NASA Astrophysics Data System (ADS)
Lientschnig, G.
2012-05-01
Magnetic field measurements of scientific spacecraft can be modelled successfully with the multiple magnetic dipole method. The existing GANEW software [1] uses a modified Gauss-Newton algorithm to find good magnetic dipole models. However, this deterministic approach relies on suitable guesses of the initial parameters which require a lot of expertise and time-consuming interaction of the user. Here, the use of probabilistic methods employing genetic algorithms is put forward. Stochastic methods like these are well- suited for providing good initial starting points for GANEW. Furthermore a computer software is reported upon that was successfully tested and used for a Cluster II satellite.
Supersolid phase in atomic gases with magnetic dipole interaction
Buehler, Adam; Buechler, Hans Peter
2011-08-15
A major obstacle for the experimental realization of a supersolid phase with cold atomic gases in an optical lattice is the weakness of the nearest-neighbor interactions achievable via magnetic dipole-dipole interactions. In this paper, we show that by using a large filling of atoms within each well, the characteristic energy scales are strongly enhanced. Within this regime, the system is well described by the rotor model, and the qualitative behavior of the phase diagram derives from mean-field theory. We find a stable supersolid phase for realistic parameters with chromium atoms.
Dynamical dipole mode in fusion reactions at 16 MeV/nucleon and beam energy dependence
NASA Astrophysics Data System (ADS)
Pierroutsakou, D.; Martin, B.; Agodi, C.; Alba, R.; Baran, V.; Boiano, A.; Cardella, G.; Colonna, M.; Coniglione, R.; Filippo, E. De; Zoppo, A. Del; Toro, M. Di; Inglima, G.; Glodariu, T.; Commara, M. La; Maiolino, C.; Mazzocco, M.; Pagano, A.; Parascandolo, C.; Piattelli, P.; Pirrone, S.; Rizzo, C.; Romoli, M.; Sandoli, M.; Santonocito, D.; Sapienza, P.; Signorini, C.
2009-08-01
High-energy γ rays and light charged particles from the Ar36+Zr96 and Ar40+Zr92 reactions at Elab=16 and 15.1 MeV/nucleon, respectively, were measured in coincidence with evaporation residues by means of the MEDEA multidetector array coupled to four parallel plate avalanche counters. The aim of this experiment was to investigate the prompt γ radiation, emitted in the decay of the dynamical dipole mode, in the ~16 MeV/nucleon energy range and to map its beam energy dependence, comparing the present results with our previous ones obtained at lower energies. The studied reactions populate, through entrance channels having different charge asymmetries, a compound nucleus in the region of Ce under the same conditions of excitation energy and spin. Light charged particle energy spectra were used to pin down the average excitation energy and the average mass of the system. By studying the γ-ray spectra of the charge symmetric reaction Ar40+Zr92, the statistical giant dipole resonance (GDR) parameters and angular distribution were extracted, and a comparison of the linearized 90°γ-ray spectra of the two reactions revealed a 12% extra yield in the GDR energy region for the more charge asymmetric system. The center-of-mass angular distribution data of this extra γ yield, compatible with a dipole oscillating along the symmetry axis of the dinuclear system, support its dynamical nature. The experimental findings are compared with theoretical predictions performed within a Boltzmann-Nordheim-Vlasov transport model and based on a collective bremsstrahlung analysis of the entrance channel reaction dynamics. An interesting sensitivity to the symmetry term of the equation of state and to in-medium effects on nucleon-nucleon (nn) cross sections is finally discussed.
IS THE TWO MICRON ALL SKY SURVEY CLUSTERING DIPOLE CONVERGENT?
Bilicki, Maciej; Chodorowski, Michal; Jarrett, Thomas; Mamon, Gary A.
2011-11-01
There is a long-standing controversy about the convergence of the dipole moment of the galaxy angular distribution (the so-called clustering dipole). Is the dipole convergent at all, and if so, what is the scale of the convergence? We study the growth of the clustering dipole of galaxies as a function of the limiting flux of the sample from the Two Micron All Sky Survey (2MASS). Contrary to some earlier claims, we find that the dipole does not converge before the completeness limit of the 2MASS Extended Source Catalog, i.e., up to 13.5 mag in the near-infrared K{sub s} band (equivalent to an effective distance of 300 Mpc h{sup -1}). We compare the observed growth of the dipole with the theoretically expected, conditional one (i.e., given the velocity of the Local Group relative to the cosmic microwave background), for the {Lambda}CDM power spectrum and cosmological parameters constrained by the Wilkinson Microwave Anisotropy Probe. The observed growth turns out to be within 1{sigma} confidence level of its theoretical counterpart once the proper observational window of the 2MASS flux-limited catalog is included. For a contrast, if the adopted window is a top hat, then the predicted dipole grows significantly faster and converges (within the errors) to its final value for a distance of about 300 Mpc h{sup -1}. By comparing the observational windows, we show that for a given flux limit and a corresponding distance limit, the 2MASS flux-weighted window passes less large-scale signal than the top-hat one. We conclude that the growth of the 2MASS dipole for effective distances greater than 200 Mpc h{sup -1} is only apparent. On the other hand, for a distance of 80 Mpc h{sup -1} (mean depth of the 2MASS Redshift Survey) and the {Lambda}CDM power spectrum, the true dipole is expected to reach only {approx}80% of its final value. Eventually, since for the window function of 2MASS the predicted growth is consistent with the observed one, we can compare the two to evaluate
Dipole rescattering and the nuclear structure function
Carvalho, F.; Goncalves, V. P.; Navarra, F. S.; Oliveira, E. G.
2013-03-25
In the framework of the dipole model, we study the effects of the dipole multiple scatterings in a nuclear target and compute the nuclear structure function. We compare different unitarization schemes and confront our results with the E665 data.
Nonadiabatic behavior of the magnetic moment of a charged particle in a dipole magnetic field
NASA Technical Reports Server (NTRS)
Murakami, Sadayoshi; Sato, Tetsuya; Hasegawa, Akira
1990-01-01
This paper investigates the dynamic behavior of the magnetic moment of a particle confined in a magnetic dipole field in the presence of a low-frequency electrostatic wave. It is shown that there exist two kinds of resonances (the bounce-E x B drift resonance and the wave-drift resonance) by which the adiabaticity of the magnetic moment is broken. The unstable conditions obtained by theoretical considerations showed good agreement with the numerical results.
Zyuzun, A. M. Bakulin, M. A.; Bezborodov, S. V.; Radaikin, V. V.; Sabaev, S. N.
2016-04-15
The factors affecting the slope of the dispersion curve of the spin-wave resonance spectrum in multilayer films are determined. It is shown that an increase in the slope of the curve for the transverse orientation of the constant magnetic field relative to the film upon an increase in frequency is due to enhancement of dynamic as well as dissipative mechanisms of spin pinning. It is found that an increase in the damping parameter increases the degree of spin pinning in the case when the pinning layer is a reactive medium for spin oscillations and can decrease the degree of pinning when it is a dispersive medium. The conditions ensuring a higher degree of accuracy in determining the exchange interaction constant from the spin-wave resonance spectrum in multilayer films are determined.
NASA Astrophysics Data System (ADS)
Kholokhonova, Polina A.; Erg, G. V.
2005-11-01
A method is proposed for the calculation of negative-dispersion mirrors with resonator cavities. The mirror optimisation algorithm combines the capabilities of the gradient method and the random search method. A multilayer mirror structure with a reflectivity R>99.9% and a group delay dispersion of -60±10 fs2 in the 930-1070 nm wavelength range was calculated. The sensitivity of the obtained structure to random variations of layer thicknesses was analysed.
2010-04-02
Environmental Technology Technical Symposium and Workshop, Washington, D.C. Cobb, W. (2006), Acoustic identification of filler materials in unexploded...Underwater UXO Using Resonance Scattered Sonar, Partners in Environmental Technology Technical Symposium and Workshop, Washington, D.C., Dec. 1-3...Nelson, H., Yoder, T, Kraus, L. and Carin L., 2009, Broadband, Multi-Aspect Scattering from UXO, Partners in Environmental Technology Technical
Optimal dipole-field profiles for emittance reduction in storage rings.
Wang, C.-X.; Wang, Y.; Peng, Y. )
2011-03-21
In recent years nonuniform dipoles with bending-radius variation have been studied for reducing storage ring emittance. According to a new minimum-emittance theory, the effects of an arbitrary dipole can be characterized with two parameters determined by the dipole. To have a better idea of the potentials of nonuniform dipoles, here we numerically explore the possible values of these two parameters and associated bending profiles for optimal emittance reduction. Such optimization results provide a useful reference for lattice designs involving nonuniform bending. Simple bending-radius profiles (a short segment of constant radius with linear ramps on the sides) were found to be close to the optimal. Basic beam and lattice properties such as emittance, energy spread, and phase advances are presented based on the optimal dipole solutions.