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Sample records for dipole resonance parameter

  1. Pygmy dipole resonance and dipole polarizability in {sup 90}Zr

    SciTech Connect

    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.

  2. Measurement of coupling resonance driving terms with the AC dipole

    SciTech Connect

    Miyamoto, R.

    2010-10-01

    Resonance driving terms for linear coupled betatron motion in a synchrotron ring can be determined from corresponding spectral lines of an excited coherent beam motion. An AC dipole is one of instruments to excite such a motion. When a coherent motion is excited with an AC dipole, measured Courant-Snyder parameters and betatron phase advance have apparent modulations, as if there is an additional quadrupole field at the location of the AC dipole. Hence, measurements of these parameters using the AC dipole require a proper interpretation of observed quantities. The situation is similar in measurements of resonance driving terms using the AC dipole. In this note, we derive an expression of coupled betatron motion excited with two AC dipoles in presence of skew quadrupole fields, discuss an impact of this quadrupole like effect of the AC dipole on a measurement of coupling resonance driving terms, and present an analytical method to determine the coupling resonance driving terms from quantities observed using the AC dipole.

  3. Interference effect in the dipole and nondipole anisotropy parameters of the Kr 4p photoelectrons in the vicinity of the Kr (3d){sup -1{yields}}np resonant excitations

    SciTech Connect

    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.

  4. Fission and dipole resonances in metal clusters

    SciTech Connect

    Martin, T. P.; Billas, I. M. L.; Branz, W.; Heinebrodt, M.; Tast, F.; Malinowski, N.

    1997-06-20

    It is not obvious that metal clusters should behave like atomic nuclei--but they do. Of course the energy and distance scales are quite different. But aside from this, the properties of these two forms of condensed matter are amazingly similar. The shell model developed by nuclear physicists describes very nicely the electronic properties of alkali metal clusters. The giant dipole resonances in the excitation spectra of nuclei have their analogue in the plasmon resonances of metal clusters. Finally, the droplet model describing the fission of unstable nuclei can be successively applied to the fragmentation of highly charged metal clusters. The similarity between clusters and nuclei is not accidental. Both systems consist of fermions moving, nearly freely, in a confined space.

  5. Splitting of the Pygmy Dipole Resonance

    NASA Astrophysics Data System (ADS)

    Endres, J.; Butler, P.; Harakeh, M. N.; Harissopulos, S.; Herzberg, R.-D.; Krücken, R.; Lagoyannis, A.; Litvinova, E.; Pietralla, N.; Ponomarev, V. Yu.; Popescu, L.; Ring, P.; Savran, D.; Scheck, M.; Sonnabend, K.; Stoica, V. I.; Wörtche, H. J.; Zilges, A.

    2011-10-01

    In recent years investigations have been made to study the electric Pygmy Dipole Resonance (PDR) systematically, mainly in semi-magic nuclei. For this purpose the well understood high resolution (γ,γ') photon scattering method is used. In complementary (α,α'γ) coincidence experiments at Eα = 136 MeV a similar γ-energy resolution and a high selectivity to E1 transitions can be obtained at the Big-Bite Spectrometer (BBS) at KVI, Groningen. In comparison to the (γ,γ') method a structural splitting of the PDR is observed in the N = 82 nuclei 138Ba and 140Ce and in the Z = 50 nucleus 124Sn. The low energy part is excited in (γ,γ') as well as in (α,α'γ) while the high energy part is observed in (γ,γ') only. The experimental results together with theoretical QPM and RQTBA calculations on 124Sn which are able to reproduce the splitting of the PDR qualitatively are presented. The low-lying group of Jπ = 1- states seem to represent the more isoscalar neutron-skin oscillation of the PDR while the energetically higher-lying states seemingly belong to the transitional region between the PDR and the isovector Giant Dipole Resonance (IVGDR).

  6. Splitting of the Pygmy Dipole Resonance

    SciTech Connect

    Endres, J.; Zilges, A.; Butler, P.; Herzberg, R.-D.; Scheck, M.; Harakeh, M. N.; Harissopulos, S.; Lagoyannis, A.; Kruecken, R.; Ring, P.; Litvinova, E.; Pietralla, N.; Ponomarev, V. Yu.; Sonnabend, K.; Popescu, L.; Savran, D.; Stoica, V. I.; Woertche, H. J.

    2011-10-28

    In recent years investigations have been made to study the electric Pygmy Dipole Resonance (PDR) systematically, mainly in semi-magic nuclei. For this purpose the well understood high resolution ({gamma},{gamma}') photon scattering method is used. In complementary ({alpha},{alpha}'{gamma}) coincidence experiments at E{sub {alpha}} = 136 MeV a similar {gamma}-energy resolution and a high selectivity to E1 transitions can be obtained at the Big-Bite Spectrometer (BBS) at KVI, Groningen. In comparison to the ({gamma},{gamma}') method a structural splitting of the PDR is observed in the N = 82 nuclei {sup 138}Ba and {sup 140}Ce and in the Z = 50 nucleus {sup 124}Sn. The low energy part is excited in ({gamma},{gamma}') as well as in ({alpha},{alpha}'{gamma}) while the high energy part is observed in ({gamma},{gamma}') only. The experimental results together with theoretical QPM and RQTBA calculations on {sup 124}Sn which are able to reproduce the splitting of the PDR qualitatively are presented. The low-lying group of J{sup {pi}} = 1{sup -} states seem to represent the more isoscalar neutron-skin oscillation of the PDR while the energetically higher-lying states seemingly belong to the transitional region between the PDR and the isovector Giant Dipole Resonance (IVGDR).

  7. Giant dipole resonance in hot rotating nuclei

    NASA Astrophysics Data System (ADS)

    Chakrabarty, D. R.; Dinh Dang, N.; Datar, V. M.

    2016-05-01

    Over the last several decades, extensive experimental and theoretical work has been done on the giant dipole resonance (GDR) in excited nuclei covering a wide range of temperature ( T), angular momentum ( J) and nuclear mass. A reasonable stability of the GDR centroid energy and an increase of the GDR width with T (in the range ˜ 1 - 3 MeV) and J are the two well-established results. Some experiments have indicated the saturation of the GDR width at high T . The gradual disappearance of the GDR vibration at much higher T has been observed. Experiments on the Jacobi transition and the GDR built on superdeformed shapes at high rotational frequencies have been reported in a few cases. Theoretical calculations on the damping of the collective dipole vibration, characterised by the GDR width, have been carried out within various models such as the thermal shape fluctuation model and the phonon damping model. These models offer different interpretations of the variation of the GDR width with T and J and have met with varying degrees of success in explaining the experimental data. In this review, the present experimental and theoretical status in this field will be discussed along with the future outlook. The interesting phenomenon of the pre-equilibrium GDR excitation in nuclear reactions will be briefly addressed.

  8. Systematic Study of the Pygmy Dipole Resonance

    NASA Astrophysics Data System (ADS)

    Derya, V.; Endres, J.; Harakeh, M. N.; Savran, D.; Wörtche, H. J.; Zilges, A.

    2012-05-01

    In recent years, a systematic comparative study of the pygmy dipole resonance (PDR) using the (γ,γ') and the (α,α'γ) reactions on the nuclei 140Ce, 138Ba, 124Sn, 94Mo, and 48Ca was performed. The aim of this systematic study is to explore the structure of the PDR by the usage of two complementary probes and several different nuclei. The real-photon scattering experiments were performed at the S-DALINAC in Darmstadt, Germany, while the (α, α'γ) coincidence experiments were performed at the Big-Bite Spectrometer (BBS) at KVI in Groningen, The Netherlands. The comparison of the results from both kinds of experiments showed an energetic splitting of the PDR into two parts that might be due to the different isospin character of these states. First experimental results of the (α, α'γ) experiments on the nuclei 94Mo and 48Ca will be presented.

  9. Splitting of the Pygmy Dipole Resonance

    NASA Astrophysics Data System (ADS)

    Savran, D.; Endres, J.; Harakeh, M. N.; Pietralla, N.; Sonnabend, K.; Stoica, V. I.; Wörtche, H. J.; van den Berg, A. M.; Zilges, A.

    2011-09-01

    We report on experiments using the (α, α' γ) method to investigate the structure of the Pygmy Dipole Resonance (PDR) in the nuclei 94Mo, 124Sn, 138Ba and 140Ce. The experiments were performed with the Big-Bite Spectrometer (BBS) at the KVI at an incident energy of Eα = 136 MeV. The method allows a clean separation of the PDR from other excitations in the same energy region by selecting the ground-state γ-decay channel. In addition, the high resolution of the γ-ray spectroscopy using high-purity Germanium detectors allows a state-to-state analysis even in the case of the rather high level density of the investigated nuclei. The comparison to (γ,γ') experiments on the same nuclei reveals a splitting of the PDR into two groups of states with different underlying structure.

  10. New Insight into the Pygmy Dipole Resonance in Stable Nuclei

    SciTech Connect

    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.

  11. 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.

  12. Spectroscopic Observation of Resonant Electric Dipole-Dipole Interactions between Cold Rydberg Atoms

    NASA Astrophysics Data System (ADS)

    Afrousheh, K.; Bohlouli-Zanjani, P.; Vagale, D.; Mugford, A.; Fedorov, M.; Martin, J. D.

    2004-11-01

    Resonant electric dipole-dipole interactions between cold Rydberg atoms were observed using microwave spectroscopy. Laser-cooled 85Rb atoms in a magneto-optical trap were optically excited to 45d5/2 Rydberg states using a pulsed laser. A microwave pulse transferred a fraction of these Rydberg atoms to the 46p3/2 state. A second microwave pulse then drove atoms in the 45d5/2 state to the 46d5/2 state, and was used as a probe of interatomic interactions. The spectral width of this two-photon probe transition was found to depend on the presence of the 46p3/2 atoms, and is due to the resonant electric dipole-dipole interaction between 45d5/2 and 46p3/2 Rydberg atoms.

  13. Enhancing Eu(3+) magnetic dipole emission by resonant plasmonic nanostructures.

    PubMed

    Hussain, Rabia; Kruk, Sergey S; Bonner, Carl E; Noginov, Mikhail A; Staude, Isabelle; Kivshar, Yuri S; Noginova, Natalia; Neshev, Dragomir N

    2015-04-15

    We demonstrate the enhancement of magnetic dipole spontaneous emission from Eu3+ ions by an engineered plasmonic nanostructure that controls the electromagnetic environment of the emitter. Using an optical microscope setup, an enhancement in the intensity of the Eu3+ magnetic dipole emission was observed for emitters located in close vicinity to a gold nanohole array designed to support plasmonic resonances overlapping with the emission spectrum of the ions. PMID:25872041

  14. Giant dipole resonances in the interacting boson model

    NASA Astrophysics Data System (ADS)

    Scholtz, F. G.; Hahne, F. J. W.

    1983-03-01

    Giant dipole resonances, represented by p bosons, are introduced into the interacting boson model. For nuclei with SU(3) symmetry the dipole is split by the interactions into two main parts, with any further fragmentation being generally small. The Raman scattering to side bands tends to be very small. This agrees with recent measurements on Er. Supported by the National Accelerator Centre, CSIR, Faure, South Africa.

  15. 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.

  16. The pygmy dipole resonance in neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Quang Hung, Nguyen; Kiet, Hoang Anh Tuan; Duc, Huynh Ngoc; Thi Chuong, Nguyen

    2016-06-01

    The pygmy dipole resonance (PDR), which has been observed via the enhancement of the electric dipole strength E1 of atomic nuclei, is studied within a microscopic collective model. The latter employs the Hartree-Fock (HF) method with effective nucleon-nucleon interactions of the Skyrme types plus the random-phase approximation (RPA). The results of the calculations obtained for various even-even nuclei such as 16-28O, 40-58Ca, 100-120Sn, and 182-218Pb show that the PDR is significantly enhanced when the number of neutrons outside the stable core of the nucleus is increased, that is, in the neutron-rich nuclei. As the result, the relative ratio between the energy weighted sum of the strength of the PDR and that of the GDR (giant dipole resonance) does not exceed 4%. The collectivity of the PDR and GDR states will be also discussed.

  17. On the nature of the Dipole Pygmy Resonance

    SciTech Connect

    Lanza, E. G.; Vitturi, A.; Andres, M. V.; Catara, F.; Gambacurta, D.

    2011-10-28

    The nature of the low-lying dipole states in neutron-rich nuclei, often associated to the Pygmy Dipole Resonance, has been investigated. This has been done by describing them within the Hartree-Fock plus RPA formalism. The analysis shows that they are not of collective nature although many particle-hole configurations participate to their formation. Taking advantage of their strong isospin mixing one can envisage combined reaction processes involving the Coulomb and different mixtures of isoscalar and isovector nuclear interactions in order to provide more hints to unveil the characteristic features of these states.

  18. Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field

    NASA Astrophysics Data System (ADS)

    Afrousheh, Kourosh; Bohlouli-Zanjani, Parisa; Carter, Jeffery; Mugford, Ashton; Martin, James D. D.

    2006-05-01

    Laser cooled Rb atoms were optically excited to 46d5/2 Rydberg states. A microwave pulse transferred a fraction of the atoms to the 47p3/2 Rydberg state. The resonant electric dipole-dipole interactions between atoms in these two states were probed using the linewidth of the two-photon microwave transitions 46d5/2 -- 47d5/2. The presence of a weak magnetic field (roughly 1 G) reduced the observed line broadening, indicating that the interaction is suppressed by the field. The field removes some of the energy degeneracies responsible foe the resonant interaction, and this is the basis for a quantitative model of the resulting suppression. A technique for the calibration of magnetic field strengths using the 34s1/2 -- 34p1/2 one-photon transition is also presented.

  19. Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field

    NASA Astrophysics Data System (ADS)

    Afrousheh, K.; Bohlouli-Zanjani, P.; Carter, J. D.; Mugford, A.; Martin, J. D. D.

    2006-06-01

    Laser-cooled Rb85 atoms were optically excited to 46d5/2 Rydberg states. A microwave pulse transferred a fraction of the atoms to the 47p3/2 Rydberg state. The resonant electric dipole-dipole interactions between atoms in these two states were probed using the linewidth of the two-photon microwave transition 46d5/2-47d5/2 . The presence of a weak magnetic field ≈0.5G reduced the observed line broadening, indicating that the interaction is suppressed by the field. The field removes some of the energy degeneracies responsible for the resonant interaction, and this is the basis for a quantitative model of the resulting suppression. A technique for the calibration of magnetic field strengths using the 34s1/2-34p1/2 one-photon transition is also presented.

  20. Investigating the Pygmy Dipole Resonance Using β Decay.

    PubMed

    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, ^{136}Xe(γ,γ^{'}), and ^{136}I [J_{0}^{π}=(1^{-})]→^{136}Xe^{*} 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. PMID:27081972

  1. 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.

  2. Decomposing the electromagnetic response of magnetic dipoles to determine the geometric parameters of a dipole conductor

    NASA Astrophysics Data System (ADS)

    Desmarais, Jacques K.; Smith, Richard S.

    2016-03-01

    A novel automatic data interpretation algorithm is presented for modelling airborne electromagnetic (AEM) data acquired over resistive environments, using a single-component (vertical) transmitter, where the position and orientation of a dipole conductor is allowed to vary in three dimensions. The algorithm assumes that the magnetic fields produced from compact vortex currents are expressed as a linear combinations of the fields arising from dipoles in the subsurface oriented parallel to the [1, 0, 0], [0, 1, 0], and [0, 0, 1], unit vectors. In this manner, AEM responses can be represented as 12 terms. The relative size of each term in the decomposition can be used to determine geometrical information about the orientation of the subsurface conductivity structure. The geometrical parameters of the dipole (location, depth, dip, strike) are estimated using a combination of a look-up table and a matrix inverted in a least-squares sense. Tests on 703 synthetic models show that the algorithm is capable of extracting most of the correct geometrical parameters of a dipole conductor when three-component receiver data is included in the interpretation procedure. The algorithm is unstable when the target is perfectly horizontal, as the strike is undefined. Ambiguities may occur in predicting the orientation of the dipole conductor if y-component data is excluded from the analysis. Application of our approach to an anomaly on line 15 of the Reid Mahaffy test site yields geometrical parameters in reasonable agreement with previous authors. However, our algorithm provides additional information on the strike and offset from the traverse line of the conductor. Disparities in the values of predicted dip and depth are within the range of numerical precision. The index of fit was better when strike and offset were included in the interpretation procedure. Tests on the data from line 15701 of the Chibougamau MEGATEM survey shows that the algorithm is applicable to situations where

  3. 750 GeV diphoton resonance and electric dipole moments

    NASA Astrophysics Data System (ADS)

    Choi, Kiwoon; Im, Sang Hui; Kim, Hyungjin; Mo, Doh Young

    2016-09-01

    We examine the implication of the recently observed 750 GeV diphoton excess for the electric dipole moments of the neutron and electron. If the excess is due to a spin zero resonance which couples to photons and gluons through the loops of massive vector-like fermions, the resulting neutron electric dipole moment can be comparable to the present experimental bound if the CP-violating angle α in the underlying new physics is of O (10-1). An electron EDM comparable to the present bound can be achieved through a mixing between the 750 GeV resonance and the Standard Model Higgs boson, if the mixing angle itself for an approximately pseudoscalar resonance, or the mixing angle times the CP-violating angle α for an approximately scalar resonance, is of O (10-3). For the case that the 750 GeV resonance corresponds to a composite pseudo-Nambu-Goldstone boson formed by a QCD-like hypercolor dynamics confining at ΛHC, the resulting neutron EDM can be estimated with α ∼(750 GeV /ΛHC) 2θHC, where θHC is the hypercolor vacuum angle.

  4. Effect of resonance dipole-dipole interaction on spectra of adsorbed SF6 molecules.

    PubMed

    Dobrotvorskaia, Anna N; Kolomiitsova, Tatiana D; Petrov, Sergey N; Shchepkin, Dmitriy N; Smirnov, Konstantin S; Tsyganenko, Alexey A

    2015-09-01

    Adsorption of SF6 on zinc oxide and on silicalite-1 was investigated by a combination of IR spectroscopy with the calculations of spectra by means of a modernized model, developed previously for liquids. Comparison of the experimental spectra and the results of modeling shows that the complex band shapes in spectra of adsorbed molecules with extremely high absorbance are due to the strong resonance dipole-dipole interaction (RDDI) rather that the surface heterogeneity or the presence of specific surface sites. Perfect agreement between calculated and observed spectra was found for ZnO, while some dissimilarity in band intensities for silicalite-1 was attributed to complicated geometry of molecular arrangement in the channels. PMID:25897721

  5. 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.

  6. Dipole-Strength Distributions up to the Giant Dipole Resonance Deduced from Photon Scattering

    NASA Astrophysics Data System (ADS)

    Schwengner, R.; Rusev, G.; Benouaret, N.; Beyer, R.; Dönau, F.; Erhard, M.; Grosse, E.; Junghans, A. R.; Kosev, K.; Klug, J.; Nair, C.; Nankov, N.; Schilling, K. D.; Wagner, A.

    2008-04-01

    Dipole-strength distributions up to the neutron-separation energies of the even-mass Mo isotopes from 92Mo to 100Mo and of the N = 50 isotones 88Sr, 89Y, 90Zr have been investigated in photon-scattering experiments using the bremsstrahlung facility at the superconducting electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf. A measurement using polarised bremsstrahlung impinging on 88Sr revealed that all resolved transitions with energies greater than 6 MeV in this nuclide except for one are E1 transitions. The intensity distributions obtained from the measured spectra after a correction for detector response and a subtraction of atomic background in the target contain a continuum part in addition to the resolved peaks. It turns out that the dipole strength in the resolved peaks amounts to about 30% of the total dipole strength while the continuum contains about 70%. In order to estimate the distribution of inelastic transitions and to correct the ground-state transitions for their branching ratios simulations of γ-ray cascades were performed. The photoabsorption cross sections obtained in this way connect smoothly to (γ, n) cross sections and give novel information about the strength on the low-energy tails of the Giant Dipole Resonances below the neutron-separation energies. The experimental cross sections are compared with predictions of a Quasiparticle-Random-Phase Approximation in a deformed basis. The calculations describe the experimentally observed increase of the dipole strengths with increasing neutron number of the Mo isotopes as a consequence of increasing nuclear deformation.

  7. Driving Rabi oscillations at the giant dipole resonance in xenon

    NASA Astrophysics Data System (ADS)

    Pabst, Stefan; Wang, Daochen; Santra, Robin

    2015-11-01

    Free-electron lasers (FELs) produce short and very intense light pulses in the XUV and x-ray regimes. We investigate the possibility to drive Rabi oscillations in xenon with an intense FEL pulse by using the unusually large dipole strength of the giant dipole resonance (GDR). The GDR decays within less than 30 as due to its position, which is above the 4 d ionization threshold. We find that intensities around 1018W /cm2 are required to induce Rabi oscillations with a period comparable to the lifetime. The pulse duration should not exceed 100 as because xenon will be fully ionized within a few lifetimes. Rabi oscillations reveal themselves also in the photoelectron spectrum in the form of Autler-Townes splittings extending over several tens of electronvolts.

  8. General magnetic transition dipole moments for electron paramagnetic resonance.

    PubMed

    Nehrkorn, Joscha; Schnegg, Alexander; Holldack, Karsten; Stoll, Stefan

    2015-01-01

    We present general expressions for the magnetic transition rates in electron paramagnetic resonance (EPR) experiments of anisotropic spin systems in the solid state. The expressions apply to general spin centers and arbitrary excitation geometry (Voigt, Faraday, and intermediate). They work for linear and circular polarized as well as unpolarized excitation, and for crystals and powders. The expressions are based on the concept of the (complex) magnetic transition dipole moment vector. Using the new theory, we determine the parities of ground and excited spin states of high-spin (S=5/2) Fe(III) in hemin from the polarization dependence of experimental EPR line intensities. PMID:25615456

  9. Strong-field dipole resonance: Limiting analytical cases

    SciTech Connect

    Uiberacker, Christoph; Jakubetz, Werner

    2009-12-15

    We investigate population dynamics in N-level systems driven beyond the linear regime by a strong external field, which couples to the system through an operator with nonzero diagonal elements. As concrete example we consider the case of dipolar molecular systems. We identify limiting cases of the Hamiltonian leading to wave functions that can be written in terms of ordinary exponentials, and focus on the limits of slowly and rapidly varying fields of arbitrary strength. For rapidly varying fields we prove for arbitrary N that the population dynamics is independent of the sign of the projection of the field onto the dipole coupling. In the opposite limit of slowly varying fields the population of the target level is optimized by a dipole resonance condition. As a result population transfer is maximized for one sign of the field and suppressed for the other one, so that a switch based on flopping the field polarization can be devised. For significant sign dependence the resonance linewidth with respect to the field strength is small. In the intermediate regime of moderate field variation, the integral of lowest order in the coupling can be rewritten as a sum of terms resembling the two limiting cases, plus correction terms for N>2, so that a less pronounced sign-dependence still exists.

  10. Magnetic dipole-dipole sensing at atomic scale using electron spin resonance STM

    NASA Astrophysics Data System (ADS)

    Choi, T.; Paul, W.; Rolf-Pissarczyk, S.; MacDonald, A.; Yang, K.; Natterer, F. D.; Lutz, C. P.; Heinrich, A. J.

    Magnetometry having both high magnetic field sensitivity and atomic resolution has been an important goal for applications in diverse fields covering physics, material science, and biomedical science. Recent development of electron spin resonance STM (ESR-STM) promises coherent manipulation of spins and studies on magnetic interaction of artificially built nanostructures, leading toward quantum computation, simulation, and sensors In ESR-STM experiments, we find that the ESR signal from an Fe atom underneath a STM tip splits into two different frequencies when we position an additional Fe atom nearby. We measure an ESR energy splitting that decays as 1/r3 (r is the separation of the two Fe atoms), indicating that the atoms are coupled through magnetic dipole-dipole interaction. This energy and distance relation enables us to determine magnetic moments of atoms and molecules on a surface with high precision in energy. Unique and advantageous aspects of ESR-STM are the atom manipulation capabilities, which allow us to build atomically precise nanostructures and examine their interactions. For instance, we construct a dice cinque arrangement of five Fe atoms, and probe their interaction and energy degeneracy. We demonstrate the ESR-STM technique can be utilized for quantum magnetic sensors.

  11. Study of Collective Dipole Excitations below the Giant Dipole Resonance at HI{gamma}S

    SciTech Connect

    Tonchev, A. P.; Howell, C. R.; Tornow, W.; Angell, C.; Boswell, M.; Karwowski, H. J.; Chyzh, A.; Kelley, J. H.; Tsoneva, N.; Wu, Y. K.

    2007-02-26

    The High-Intensity Gamma-ray Source utilizing intra-cavity back-scattering of free electron laser photons from relativistic electrons allows one to produce a unique beam of high-flux gamma rays with 100% polarization and selectable energy and energy resolution which is ideal for low-energy {gamma}-ray scattering experiments. Nuclear resonance fluorescence experiments have been performed on N=82 nuclei. High sensitivity studies of E1 and M1 excitations at energies close to the neutron emission threshold have been performed. The method allows the determination of excitation energies, spin, parities, and decay branching ratios of the pygmy dipole mode of excitation. The observations are compared with calculations using statistical and quasi-particle random-phase approximations.

  12. 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.

  13. Coherent dipole-dipole coupling between two single Rydberg atoms at an electrically-tuned Förster resonance

    NASA Astrophysics Data System (ADS)

    Ravets, Sylvain; Labuhn, Henning; Barredo, Daniel; Béguin, Lucas; Lahaye, Thierry; Browaeys, Antoine

    2014-12-01

    Resonant energy transfers, the non-radiative redistribution of an electronic excitation between two particles coupled by the dipole-dipole interaction, lie at the heart of a variety of phenomena, notably photosynthesis. In 1948, Förster established the theory of fluorescence resonant energy transfer (FRET) between broadband, nearly-resonant donors and acceptors. The 1/R6 scaling of the energy transfer rate, where R is the distance between particles, enabled widespread use of FRET as a `spectroscopic ruler’ for determining nanometric distances in biomolecules. The underlying mechanism is a coherent dipolar coupling between particles, as recognized in the early days of quantum mechanics, but this coherence has not been directly observed so far. Here we study, spectroscopically and in the time domain, the coherent, dipolar-induced exchange of excitations between two Rydberg atoms separated by up to 15 μm, and brought into resonance by applying an electric field. Coherent oscillation of the system between two degenerate pair states then occurs at a frequency scaling as 1/R3, the hallmark of resonant dipole-dipole interactions. Our results not only demonstrate, at the fundamental level of two atoms, the basic mechanism underlying FRET, but also open exciting prospects for active tuning of strong, coherent interactions in quantum many-body systems.

  14. Isoscalar Giant Dipole Resonance within Fermi Liquid Drop Model

    NASA Astrophysics Data System (ADS)

    Pochivalov, Oleksiy; Shlomo, Shalom

    2006-04-01

    Recent highly accurate experimental data on Isoscalar Giant Dipole (ISGDR) and Monopole (ISGMR) Resonances in nuclei renewed interest in correct microscopic description of collective excitations. Hartree-Fock based Random-Phase-Approximation (HF-RPA) is a successful method of describing collective excitations in nuclei. However, recent fully self-consistent HF-RPA calculations, which reproduce the centroid energies of the ISGMR, systematically overestimate by 1.5-2.5 MeV results for the ISGDR energy comparing with experimentally obtained data. Also, the HF-RPA model does not provide description of the widths of giant resonances. We consider these issues within the semi-classical generalization of the mean field theory, namely, Fermi-Liquid-Drop-Model (FLDM). In this presentation, we provide description of the FLDM formalism in its application to ISGDR and ISGMR calculations. We present results of FLDM calculations for centroid energy and widths of the ISGDR and ISGMR in the four nuclei, namely, 90Zr, 116Sn, 144Sm, and 208Pb and compare with available experimental data.

  15. Giant dipole resonance in hot and rotating nuclei

    NASA Astrophysics Data System (ADS)

    Banerjee, Sudhee R.

    2013-04-01

    The study of Giant Dipole Resonance (GDR) even after more than 60 years of its discovery, still remains an intriguing and a very relevant topic of research particularly in the case of hot and fast rotating nuclei. Many new facets of this giant collective mode of vibration are being brought to light recently owing to the new age powerful detection systems. Particularly for the nuclei with large asymmetries in its neutron and protons the study of its GDR decay modes opened up very interesting research prospects worldwide. Even with low energy light-ion and heavy-ion accelerated beams and employing the powerful large volume high energy photon spectrometer LAMBDA at VECC a number of very interesting experimental observations have been made recently which radically changes the present understanding of GDR vibrations in moderately hot nuclei in general. The availability of higher energy heavy-ion beams from the near ready superconducting cyclotron at VECC will open up many more interesting and challenging research prospects with the LAMBDA spectrometer. Exciting challenges and opportunities are also on offer for studying the properties and dynamics of hot exotic nuclei with stable and RI beams through high energy gamma decays from giant resonances. A few of the very interesting results obtained recently at VECC with the LAMBDA spectrometer, further research possibilities and several other powerful detector facilities will be discussed during the conference.

  16. On field line resonances of hydromagnetic Alfven waves in dipole magnetic field

    SciTech Connect

    Chen, Liu; Cowley, S.C. )

    1989-08-01

    Using the dipole magnetic field model, the authors 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.

  17. On field line resonances of hydromagnetic Alfven waves in dipole magnetic field

    SciTech Connect

    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.

  18. 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.

  19. Measurement of giant dipole resonance width at low temperature: A new experimental perspective

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Pandit, Deepak; Pal, Surajit; Bhattacharya, Srijit; De, A.; Bhattacharya, S.; Bhattacharya, C.; Banerjee, K.; Kundu, S.; Rana, T. K.; Mukherjee, G.; Pandey, R.; Gohil, M.; Pai, H.; Meena, J. K.; Banerjee, S. R.

    2012-03-01

    The systematic evolution of the giant dipole resonance (GDR) width in the temperature region of 0.9- 1.4 MeV has been measured experimentally for 119Sb using alpha induced fusion reaction and employing the LAMBDA high energy photon spectrometer. The temperatures have been precisely determined by simultaneously extracting the vital level density parameter from the neutron evaporation spectrum and the angular momentum from gamma multiplicity filter using a realistic approach. The systematic trend of the data seems to disagree with the thermal shape fluctuation model (TSFM). The model predicts the gradual increase of GDR width from its ground state value whereas the measured GDR widths appear to remain constant at the ground state value till T ∼ 1 MeV and increase thereafter, indicating towards a failure of the adiabatic assumption of the model at low temperature.

  20. Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances

    SciTech Connect

    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.

  1. 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.

  2. 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.

  3. Dipole-Strength Distributions Below the Giant Dipole Resonance in the Stable Even-Mass Molybdenum Isotopes

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Angell, C. T.; Beyer, R.; Dönau, F.; Erhard, M.; Grosse, E.; Hammond, S. L.; Hutcheson, A. L.; Frauendorf, S.; Junghans, A. R.; Kawowski, H. J.; Kelley, J. H.; Klug, J.; Kosev, K.; Kwan, E.; Nair, C.; Nikolov, N.; Schilling, K.-D.; Schwengner, R.; Tonchev, A. P.; Tornow, W.; Wagner, A.

    2009-03-01

    Dipole-strength distributions in the stable even-mass molybdenum isotopes up to the neutron-separation energies have been studied in photon-scattering experiments with bremsstrahlung at the superconducting electron accelerator ELBE at the Research Center Dresden-Rossendorf, Germany, and with mono-energetic photon beams at the High Intensity Gamma-ray Source facility at Triangle Universities Nuclear Laboratory. In order to determine the dipole-strength distribution, statistical methods were developed for the analysis of the measured spectra. The data obtained for the stable even-mass molybdenum isotopes from the present (γ,γ') experiments are combined with (γ,n) cross sections from the literature resulting in a photoabsorption cross section covering the full range from about 4 to 15 MeV, which is of interest for nuclear structure as well as for nuclear astrophysics network calculations. Novel information about the low-energy tail of the Giant Dipole Resonance and the energy spreading of its strength is derived.

  4. Dipole-Strength Distributions Below the Giant Dipole Resonance in the Stable Even-Mass Molybdenum Isotopes

    SciTech Connect

    Rusev, G.; Hutcheson, A. L.; Kwan, E.; Tonchev, A. P.; Tornow, W.; Angell, C. T.; Hammond, S. L.; Kawowski, H. J.; Beyer, R.; Doenau, F.; Erhard, M.; Grosse, E.; Frauendorf, S.; Junghans, A. R.; Klug, J.; Kosev, K.; Nair, C.; Nikolov, N.; Schilling, K.-D.; Schwengner, R.

    2009-03-10

    Dipole-strength distributions in the stable even-mass molybdenum isotopes up to the neutron-separation energies have been studied in photon-scattering experiments with bremsstrahlung at the superconducting electron accelerator ELBE at the Research Center Dresden-Rossendorf, Germany, and with mono-energetic photon beams at the High Intensity Gamma-ray Source facility at Triangle Universities Nuclear Laboratory. In order to determine the dipole-strength distribution, statistical methods were developed for the analysis of the measured spectra. The data obtained for the stable even-mass molybdenum isotopes from the present ({gamma},{gamma}') experiments are combined with ({gamma},n) cross sections from the literature resulting in a photoabsorption cross section covering the full range from about 4 to 15 MeV, which is of interest for nuclear structure as well as for nuclear astrophysics network calculations. Novel information about the low-energy tail of the Giant Dipole Resonance and the energy spreading of its strength is derived.

  5. Integral data analysis for resonance parameters determination

    SciTech Connect

    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.

  6. Design Concept and Parameters of a 15 T $Nb_{3}Sn$ Dipole Demonstrator for a 100 TEV Hadron Collider

    SciTech Connect

    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.

  7. Pygmy dipole resonance as a constraint on the neutron skin of heavy nuclei

    SciTech Connect

    Piekarewicz, J.

    2006-04-15

    The isotopic dependence of the isovector Pygmy dipole response in tin is studied within the framework of the relativistic random-phase approximation. Regarded as an oscillation of the neutron skin against the isospin-symmetric core, the pygmy dipole resonance may place important constraints on the neutron skin of heavy nuclei and, as a result, on the equation of state of neutron-rich matter. The present study centers around two questions. First, is there a strong correlation between the development of a neutron skin and the emergence of low-energy isovector dipole strength? Second, could one use the recently measured Pygmy dipole resonance in {sup 130}Sn and {sup 132}Sn to discriminate among theoretical models? For the first question we found that although a strong correlation between the neutron skin and the Pygmy dipole resonance exists, a mild anticorrelation develops beyond {sup 120}Sn. The answer to the second question suggests that models with overly large neutron skins--and thus stiff symmetry energies--are in conflict with experiment.

  8. Evolution of the pygmy dipole resonance in nuclei with neutron excess

    SciTech Connect

    Co', G.; Donno, V. De; Maieron, C.; Anguiano, M.; Lallena, A. M.

    2009-07-15

    The electric dipole excitation of various nuclei is calculated with a Random Phase Approximation phenomenological approach. The evolution of the strength distribution in various groups of isotopes of oxygen, calcium, zirconium, and tin is studied. The neutron excess produces E1 strength in the low-energy region. Indexes to measure the collectivity of the excitation are defined. We studied the behavior of proton and neutron transition densities to determine the isoscalar or isovector nature of the excitation. We observed that in medium-heavy nuclei the low-energy E1 excitation has characteristics rather different than those exhibited by the giant dipole resonance. This new type of excitation can be identified as a pygmy dipole resonance.

  9. An MHD simulation study of the poloidal mode field line resonance in the Earth's dipole magnetosphere

    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.

  10. Resonance Method of Electric-Dipole-Moment Measurements in Storage Rings

    SciTech Connect

    Orlov, Yuri F.; Morse, William M.; Semertzidis, Yannis K.

    2006-06-02

    A 'resonance method' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles' velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.

  11. RESONANCE METHOD OF ELECTRIC-DIPOLE-MOMENT MEASUREMENTS IN STORAGE RINGS.

    SciTech Connect

    ORLOV, Y.F.; MORSE, W.M.; SEMERTZIDIS, Y.K.

    2006-05-10

    A ''resonance method'' of measuring the electric dipole moment (EDM) of nuclei in storage rings is described, based on two new ideas: (1) Oscillating particles velocities in resonance with spin precession, and (2) alternately producing two sub-beams with different betatron tunes--one sub-beam to amplify and thus make it easier to correct ring imperfections that produce false signals imitating EDM signals, and the other to make the EDM measurement.

  12. The Isoscalar Giant Dipole Resonance in {sup 20}Pb, {sup 90}Zr and the Nuclear Compressibility

    SciTech Connect

    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.

  13. 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.

  14. 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.

  15. 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.

  16. Splitting of the isovector giant dipole resonance in neutron-rich spherical nuclei

    SciTech Connect

    Kolomietz, V.M.; Magner, A.G.; Shlomo, S.

    2006-02-15

    The well-known splitting of the isovector giant dipole resonance is traditionally explained as a phenomenon of the nuclear isospin asymmetry (isospin splitting model) or the nuclear deformation. We suggest a new mechanism of the splitting of the giant multipole resonances in spherical neutron-rich nuclei resulting from the interplay of the isovector and isoscalar sounds with different velocities. Our approach is based on the collisional Landau kinetic theory and can be used for description of the splitting phenomena for both the isoscalar and the isovector modes in a wide region of nuclear masses A{approx}40-240. For the isovector dipole modes, the evaluated values of the splitting energy, the relative strength of the main and satellite resonance peaks, and the contribution to the energy-weighted sum rule are in agreement with experimental data.

  17. Evidence of Soft Dipole Resonance in 11Li with Isoscalar Character

    DOE PAGESBeta

    Kanungo, R.; Sanetullaev, A.; Jansen, Gustav R.; Tanaka, J.; Ishimoto, S.; Myo, T.; Suzuki, T.; Andreoiu, C.; Bender, P.; Chen, A. A.; et al

    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

  18. Evidence of Soft Dipole Resonance in 11Li with Isoscalar Character

    SciTech Connect

    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 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 in the coupled cluster framework are also included.

  19. The gamma decay of the giant dipole resonance: from zero to finite temperature

    NASA Astrophysics Data System (ADS)

    Bracco, Angela; Camera, Franco

    2016-08-01

    This paper is intended to give a selected and rather brief overview of the work made in the last thirty years to study the properties of the giant dipole resonance focusing in particular on nuclei formed at finite temperatures using heavy ion reactions. The physical problems that are discussed (using examples of particular results) in this paper can be grouped into 3 major topics: (i) the temperature dependence of the GDR width; (ii) the dipole oscillation in reaction dynamics; (iii) the isospin mixing at finite temperature.

  20. 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.

  1. Effects of Head Models and Dipole Source Parameters on EEG Fields

    PubMed Central

    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

  2. Dephasing due to Nuclear Spins in Large-Amplitude Electric Dipole Spin Resonance

    NASA Astrophysics Data System (ADS)

    Chesi, Stefano; Yang, Li-Ping; Loss, Daniel

    2016-02-01

    We analyze effects of the hyperfine interaction on electric dipole spin resonance when the amplitude of the quantum-dot motion becomes comparable or larger than the quantum dot's size. Away from the well-known small-drive regime, the important role played by transverse nuclear fluctuations leads to a Gaussian decay with characteristic dependence on drive strength and detuning. A characterization of spin-flip gate fidelity, in the presence of such additional drive-dependent dephasing, shows that vanishingly small errors can still be achieved at sufficiently large amplitudes. Based on our theory, we analyze recent electric dipole spin resonance experiments relying on spin-orbit interactions or the slanting field of a micromagnet. We find that such experiments are already in a regime with significant effects of transverse nuclear fluctuations and the form of decay of the Rabi oscillations can be reproduced well by our theory.

  3. Recent results on giant dipole resonance decays in highly excited nuclei

    SciTech Connect

    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.

  4. Recent results on giant dipole resonance decays in highly excited nuclei

    SciTech Connect

    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.

  5. Giant Dipole Resonance decay of hot rotating 88Mo

    NASA Astrophysics Data System (ADS)

    Ciemała, M.; Kmiecik, M.; Maj, A.; Kravchuk, V. L.; Gramegna, F.; Barlini, S.; Casini, G.; Camera, F.

    2014-03-01

    An experiment focusing on study of the properties of hot rotating compound nucleus of 88Mo was performed in LNL Legnaro using 48Ti beam at energies of 300 and 600 MeV on 40Ca target. The compound nucleus was produced at the temperatures of 3 and 4.5 MeV, with angular momentum distribution with lmax > 60 ħ (i.e. exceeding the crtical angular momentum for fission). High-energy gamma rays, measured in coincidence with evaporation residues and alpha particles, were analyzed with the statistical model. The GDR parameters were obtained from the best fit to the data, which allowed investigating an evolution of the GDR width up to high temperatures.

  6. Rashba coupling in three-dimensional wurtzite structure electron gas at electric-dipole spin resonance

    NASA Astrophysics Data System (ADS)

    Ungier, W.

    2014-05-01

    Theoretical description of Rashba effects in three-dimensional electron gas at electric-dipole spin resonance conditions is presented in the frame of conductivity tensor formalism. The details due to anisotropy of the effective mass tensor, as well as the Lande factor, are considered. The absorbed power is calculated for arbitrary orientation of the sample with respect to external fields: constant magnetic field and rf electric field. The differences between resonance signals in two- and three-dimensional electron gas are pointed out.

  7. Giant dipole resonance built on hot rotating nuclei produced during evaporation of light particles from the 88Mo compound nucleus

    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.

  8. Paramagnetic dipole centers in KTaO3: Electron-spin-resonance and dielectric spectroscopy study

    NASA Astrophysics Data System (ADS)

    Laguta, V. V.; Glinchuk, M. D.; Bykov, I. P.; Rosa, J.; Jastrabík, L.; Savinov, M.; Trybuła, Z.

    2000-02-01

    Electron-spin-resonance (ESR) and dielectric spectroscopy techniques have been applied to study the dipole centers connected with Mn2+ and Fe3+ impurity ions substituted for K+ in the incipient ferroelectric KTaO3. It was shown that the reorientations of paramagnetic dipole complexes Fe3+-OI (OI is the interstitial oxygen) give rise to dielectric losses near T~=185 K at the frequency 1 kHz. Their activation energy Er=0.34 eV was obtained both from dielectric and ESR measurements. The peak of dielectric losses at T~=55 K was observed in KTaO3 doped by low concentrations of Mn2+(n~0.01 at. %). At n>~0.3 at. % a pronounced peak of dielectric susceptibility similar to that in KTaO3:Li was revealed in addition to the aforementioned losses peak. The studies of electric field and temperature dependence of Mn2+ ESR intensities with respect to the local Lorentz field had shown that the dipole moment 1.4 eÅ can be associated with Mn2+ ion. The origin of this dipole moment was shown to be off-center displacement Δ~=0.9 Å of Mn2+ from the K+ site in one of six [001]-type directions. The relaxation rate of these dipoles after the polarizing electric field switching off was directly measured by the ESR method. It was described by Arrhenius law with activation energy Er=0.104 eV, which is close to the value obtained from dielectric measurements. Possible sources of dielectric losses in nominally pure KTaO3 single crystals in the vicinity of T~40 K are analyzed and discussed on the basis of both present work data and earlier results collected from the literature.

  9. Role of surface plasmon polaritons and other waves in the radiation of resonant optical dipole antennas

    PubMed Central

    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

  10. Fragmentation and systematics of the pygmy dipole resonance in the stable N=82 isotones

    SciTech Connect

    Savran, D.; Loeher, B.; Elvers, M.; Endres, J.; Zilges, A.; Fritzsche, M.; Pietralla, N.; Ponomarev, V. Yu.; Romig, C.; Schnorrenberger, L.; Sonnabend, K.

    2011-08-15

    The low-lying electric dipole (E1) strength in the semimagic nucleus {sup 136}Xe has been measured, which finalizes the systematic survey to investigate the so-called pygmy dipole resonance (PDR) in all stable even N=82 isotones with the method of nuclear resonance fluorescence using real photons in the entrance channel. In all cases, a fragmented resonance-like structure of E1 strength is observed in the energy region 5-8 MeV. An analysis of the fragmentation of the strength reveals that the degree of fragmentation decreases toward the proton-deficient isotones, while the total integrated strength increases, indicating a dependence of the total strength on the neutron-to-proton ratio. The experimental results are compared to microscopic calculations within the quasiparticle phonon model. The calculation includes complex configurations of up to three phonons and is able to reproduce also the fragmentation of the E1 strength, which allows us to draw conclusions on the damping of the PDR. Calculations and experimental data are in good agreement on the degree of fragmentation and also on the integrated strength if the sensitivity limit of the experiments is taken into account.

  11. Resonance Parameter Adjustment Based on Integral Experiments

    DOE PAGESBeta

    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, 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

  12. Molecular near-field antenna effect in resonance hyper-Raman scattering: intermolecular vibronic intensity borrowing of solvent from solute through dipole-dipole and dipole-quadrupole interactions.

    PubMed

    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. PMID:24880300

  13. Rho resonance parameters from lattice QCD

    NASA Astrophysics Data System (ADS)

    Guo, Dehua; Alexandru, Andrei; Molina, Raquel; Döring, Michael

    2016-08-01

    We perform a high-precision calculation of the phase shifts for π -π scattering in the I =1 , J =1 channel in the elastic region using elongated lattices with two mass-degenerate quark flavors (Nf=2 ). We extract the ρ resonance parameters using a Breit-Wigner fit at two different quark masses, corresponding to mπ=226 MeV and mπ=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, mρ=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.

  14. Simplest photonuclear reactions accompanied by the excitation of isovector giant dipole and quadrupole resonances: Semimicroscopic description

    SciTech Connect

    Tulupov, B. A.; Urin, M. H.

    2012-09-15

    A semimicroscopic approach based on the continuum version of the random-phase approximation (CRPA) and on a semiphenomenological inclusion of the fragmentation effect is applied to describing cross sections for photoabsorption and direct plus semidirect and inverse reactions accompanied by the excitation of isovector giant dipole and quadrupole resonances. In addition to the spinless part of the Landau-Migdal interaction and a partly self-consistent phenomenological mean field of the nucleus, that version of the approach which is used here takes into account isovector separable velocity-dependent forces, as well as the effect of the fragmentation shift of the giant-resonance energy. The results obtained by calculating various features of the aforementioned cross sections for a number of magic and semimagic medium-mass nuclei are compared with respective experimental data.

  15. Position-dependent property of resonant dipole—dipole interaction mediated by localized surface plasmon of an Ag nanosphere

    NASA Astrophysics Data System (ADS)

    Xu, Dan; Wang, Xiao-Yun; Huang, Yong-Gang; Ouyang, Shi-Liang; He, Hai-Long; He, Hao

    2015-02-01

    We use the photon Green-function method to study the quantum resonant dipole-dipole interaction (RDDI) induced by an Ag nanosphere (ANP). As the distance between the two dipoles increases, the RDDI becomes weaker, which is accompanied by the influence of the higher-order mode of the ANP on RDDI declining more quickly than that of the dipole mode. Across a broad frequency range (above 0.05 eV), the transfer rate of the RDDI is nearly constant since the two dipoles are fixed at the proper position. In addition, this phenomenon still exists for slightly different radius of the ANPs. We find that the frequency corresponding to the maximum transfer rate of RDDI exhibits a monotonic decrease by moving away one dipole as the other dipole and the ANP are kept fixed. In addition, the radius of ANP has little effect on this. When the two dipoles are far from the ANP, the maximum transfer rate of the RDDI takes place at the frequency of the dipole mode. In contrast, when the two dipoles are close to the ANP, the higher-order modes come into effect and they will play a leading role in the RDDI if they match the transition frequency of the dipole. Our results may be used in a biological detector and have a certain guiding significance for further application. Project supported by the National Natural Science Foundation of China (Grant Nos. 11347215, 11464014, and 11104113), the Natural Science Foundation of Hunan Province, China (Grant Nos. 13JJ6059 and 13JJB015), and the Natural Science Foundation of Education Department of Hunan Province, China (Grant Nos. 13C750 and 13B091).

  16. Resonance parameter measurements and analysis of gadolinium

    SciTech Connect

    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)

  17. Impact-parameter dependent color glass condensate dipole model and new combined HERA data

    NASA Astrophysics Data System (ADS)

    Rezaeian, Amir H.; Schmidt, Ivan

    2013-10-01

    The impact-parameter dependent color glass condensate (b-CGC) dipole model is based on the Balitsky-Kovchegov nonlinear evolution equation and improves the Iancu-Itakura-Munier dipole model by incorporating the impact-parameter dependence of the saturation scale. Here we confront the model to the recently released high precision combined Hadron Electron Ring Accelerator (HERA) data and obtain its parameters. The b-CGC results are then compared to data at small x for the structure function, the longitudinal structure function, the charm structure function, exclusive vector meson (J/ψ, ϕ, and ρ) production and deeply virtual Compton scattering. We also compare our results with the impact-parameter dependent saturation (IP-Sat) model. We show that most features of inclusive deep inelastic scattering and exclusive diffractive data, including the Q2, W, |t|, and x dependence, are correctly reproduced in both models. Nevertheless, the b-CGC and the impact-parameter dependent saturation (IP-Sat) models give different predictions beyond the current HERA kinematics, namely for the structure functions at very low x and high virtualities Q2, and for the exclusive diffractive vector meson and deeply virtual Compton scattering production at high t. This can be traced back to the different power-law behavior of the saturation scale in x and to a different impact-parameter b dependence of the saturation scale in these models. Nevertheless, both models give approximately similar saturation scales QS<1GeV for the proton in HERA kinematics, and also both models lead to the same conclusion that the typical impact parameter probed in the total γ*p cross section is about b≈2-3GeV-1. Our results provide a benchmark for further investigation of QCD at small x in heavy ion collisions at RHIC and the LHC and also at future experiments such as an electron-ion collider and the LHeC.

  18. An exact analytical solution for the evolution of a dipole-dipole interacting system under spherical diffusion in magnetic resonance experiments.

    PubMed

    Sturniolo, Simone; Pieruccini, Marco

    2012-10-01

    A model system consisting of an isotropic ensemble of spin pairs, where dipole-dipole interaction is assumed to be effective only within each pair, is considered. The ideal segment connecting the spins in a couple has a fixed length but is free to rotate following a diffusion dynamics. This allows the free induction decay (FID) to be derived non-perturbatively by solving the appropriate Dyson equation associated to the problem. Motional narrowing can be described analytically in terms of only two parameters, i.e. the coupling constant of the interaction hamiltonian, b, and the orientational diffusion coefficient D. Salient features of the transverse correlation function thus obtained are discussed, and a comparison with numerical simulations performed with the software SPINEVOLUTION is presented. Interpreting b and D as effective parameters describing multiple interactions of a single spin with its neighbors in a real system, the analysis of published experimental data on poly(ethyl acrylate) has been carried out. It is found that for temperatures higher than and not too close to the glass transition, the results are the same as those found within the Anderson-Weiss approach by assuming a single time exponential decay of the average dipole-dipole interaction. On the other hand, as D tends to zero, FID oscillations characteristic of a rigid lattice show up. PMID:22975242

  19. Shear-viscosity to entropy-density ratio from giant dipole resonances in hot nuclei

    SciTech Connect

    Nguyen Dinh Dang

    2011-09-15

    The Green-Kubo relation and fluctuation-dissipation theorem are employed to calculate the shear viscosity {eta} of a finite hot nucleus directly from the width and energy of the giant dipole resonance (GDR) of this nucleus. The ratio {eta}/s of shear viscosity {eta} to entropy density s is extracted from the experimental systematics of the GDR in copper, tin, and lead isotopes at finite temperature T. These empirical results are then compared with the predictions by several independent models as well as with almost model-independent estimations. Based on these results, it is concluded that the ratio {eta}/s in medium and heavy nuclei decreases with increasing temperature T to reach (1.3--4)x({h_bar}/2{pi})/(4{pi}k{sub B}) at T=5 MeV.

  20. Hyperfine interaction mediated electric-dipole spin resonance: the role of frequency modulation

    NASA Astrophysics Data System (ADS)

    Li, Rui

    2016-05-01

    The electron spin in a semiconductor quantum dot can be coherently controlled by an external electric field, an effect called electric-dipole spin resonance (EDSR). Several mechanisms can give rise to the EDSR effect, among which there is a hyperfine mechanism, where the spin-electric coupling is mediated by the electron–nucleus hyperfine interaction. Here, we investigate the influence of frequency modulation (FM) on the spin-flip efficiency. Our results reveal that FM plays an important role in the hyperfine mechanism. Without FM, the electric field almost cannot flip the electron spin the spin-flip probability is only about 20%. While under FM, the spin-flip probability can be improved to approximately 70%. In particular, we find that the modulation amplitude has a lower bound, which is related to the width of the fluctuated hyperfine field.

  1. Neutron-skin thickness from the study of the anti-analog giant dipole resonance

    SciTech Connect

    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.

  2. EXPOSURE OF MAN IN THE NEAR-FIELD OF A RESONANT DIPOLE: COMPARISON BETWEEN THEORY AND MEASUREMENTS

    EPA Science Inventory

    The rate of the radiofrequency energy deposition in a model of the human body exposed in the near-field of a resonant dipole at 350 MHz was calculated using the moment method. Detailed maps of the electric field intensity in a similar model under the same exposure conditions were...

  3. Evidence of Soft Dipole Resonance in Li 11 with Isoscalar Character

    NASA Astrophysics Data System (ADS)

    Kanungo, R.; Sanetullaev, A.; Tanaka, J.; Ishimoto, S.; Hagen, G.; 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.; Jansen, G.; Keefe, M.; Krücken, 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.

    2015-05-01

    The first conclusive evidence of a dipole resonance in Li 11 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 Li 11 . The first ab initio calculations in the coupled cluster framework are also presented.

  4. Constraints on the neutron skin and symmetry energy from the anti-analog giant dipole resonance in 208Pb

    NASA Astrophysics Data System (ADS)

    Cao, Li-Gang; Roca-Maza, X.; Colò, G.; Sagawa, H.

    2015-09-01

    We investigate the impact of the neutron skin thickness, Δ Rn p , on the energy difference between the anti-analog giant dipole resonance (AGDR), EAGDR, and the isobaric analog state (IAS), EIAS, in a heavy nucleus such as 208Pb. For guidance, we first develop a simple and analytic, yet physical, approach based on the droplet model that linearly connects the energy difference EAGDR-EIAS with Δ Rn p . To test this correlation on more fundamental grounds, we employ a family of systematically varied Skyrme energy density functionals where variations on the value of the symmetry energy at saturation density J are explored. The calculations have been performed within the fully self-consistent Hartree-Fock (HF) plus charge-exchange random phase approximation (RPA) framework. We confirm the linear correlation within our microscopic approach and we can compare our results with available experimental data in 208Pb in order to extract a preferred value for Δ Rn p and, in turn, for the symmetry energy parameters. Averaging the results from two available experimental data, our analysis gives Δ Rn p = 0.236 ±0.018 fm, J = 33.2 ±1.0 MeV, and a slope parameter of the symmetry energy at saturation L = 97.3 ±11.2 MeV. The errors include the experimental uncertainties and a lower-limit estimate of model uncertainties. These results are consistent with those extracted from different experimental data albeit L and Δ Rn p are somewhat large when compared to previous estimations based on giant resonance studies. Possible hints whether model dependence can explain this difference are provided.

  5. Giant Dipole Resonance in the hot and thermalized 132Ce nucleus: damping of collective modes at finite temperature

    SciTech Connect

    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.

  6. Hyperfine interaction mediated electric-dipole spin resonance: The role of the frequency modulation

    NASA Astrophysics Data System (ADS)

    Li, Rui

    The electron spin in semiconductor quantum dot can be coherently controlled by an external electric field, an effect called electric-dipole spin resonance (EDSR). There are several mechanisms underlie the EDSR, among which there is a hyperfine mechanism, where the spin-electric coupling is mediated by the electron-nucleus hyperfine interaction. Here, we investigate the influence of the frequency modulation (FM) to the driving electric field on the spin-flip efficiency. Our results reveal that FM plays an important role in the hyperfine mechanism. Without FM, the electric field almost cannot flip the electron spin, the spin-flip probability is only about 20%. While under the FM, the spin-flip probability can be improved approximately to 70%. Especially, we find there is a lower bound on the modulation amplitude, which is related to the width of the hyperfine field fluctuation of the nuclear spins. This work is supported by National Natural Science Foundation of China Grant No. 11404020 and Postdoctoral Science Foundation of China Grant No. 2014M560039.

  7. Extreme nuclear shapes examined via giant dipole resonance lineshapes in hot light-mass systems

    SciTech Connect

    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.

  8. Giant dipole resonance width in nuclei near Sn at low temperature and high angular momentum

    SciTech Connect

    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.

  9. Enabling automated magnetic resonance imaging-based targeting assessment during dipole field navigation

    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.

  10. 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.

  11. 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].

  12. Giant dipole resonance width in nuclei near Sn at low temperature and high angular momentum

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Srijit; Mukhopadhyay, S.; Pandit, Deepak; Pal, Surajit; de, A.; Bhattacharya, S.; Bhattacharya, C.; Banerjee, K.; Kundu, S.; Rana, T. K.; Dey, A.; Mukherjee, G.; Ghosh, T.; Gupta, D.; Banerjee, S. R.

    2008-02-01

    High energy γ rays in coincidence with low energy yrast γ rays have been measured from Sb113, at excitation energies of 109 and 122 MeV, formed by bombarding Ne20 on Nb93 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 (Γ). The maximum populated angular momenta for fusion were 67ℏ and 73ℏ, respectively, for the above-mentioned beam energies. The high energy photons were detected using a Large Area Modular BaF2 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.

  13. A dynamically tunable terahertz metamaterial absorber based on an electrostatic MEMS actuator and electrical dipole resonator array

    NASA Astrophysics Data System (ADS)

    Hu, Fangrong; Xu, Ningning; Wang, Weiming; Wang, Yue'e.; Zhang, Wentao; Han, Jiaguang; Zhang, Weili

    2016-02-01

    We experimentally demonstrate a dynamically tunable terahertz (THz) metamaterial absorber based on an electrostatic microelectromechanical systems (MEMS) actuator and electrical dipole resonator array. The absorption of the THz wave is mainly a result of the electrical dipole resonance, which shows a tunable performance on demand. By preforming the finite integral technique, we discovered that the central absorption frequency and the amplitude can be simultaneously tuned by the applied voltage U. Characterized by a white light interferometer and a THz time domain spectroscopy system, our THz absorber is measured to show a modulation of the central frequency and the amplitude to about 10% and 20%, respectively. The experimental results show good agreement with the simulation. This dynamically tunable absorber has potential applications on THz filters, modulators and controllers.

  14. Intense {gamma}-Ray Source in the Giant-Dipole-Resonance Range Driven by 10-TW Laser Pulses

    SciTech Connect

    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

  15. Intense gamma-ray source in the giant-dipole-resonance range driven by 10-TW laser pulses.

    PubMed

    Giulietti, A; Bourgeois, N; Ceccotti, T; Davoine, X; Dobosz, S; D'Oliveira, P; Galimberti, M; Galy, J; Gamucci, A; Giulietti, D; Gizzi, L A; Hamilton, D J; Lefebvre, E; Labate, L; Marquès, J R; Monot, P; Popescu, H; Réau, F; Sarri, G; Tomassini, P; Martin, P

    2008-09-01

    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

  16. Molecular near-field antenna effect in resonance hyper-Raman scattering: Intermolecular vibronic intensity borrowing of solvent from solute through dipole-dipole and dipole-quadrupole interactions

    SciTech Connect

    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.

  17. 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.

  18. 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.

  19. 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.

  20. Time-reversal of the evolution of a dipole-coupled, many-spin system under continuous resonant irradiation

    NASA Astrophysics Data System (ADS)

    Michal, Carl A.; Tycko, Robert

    2001-01-01

    Time-reversal of the evolution of a dipole-coupled, many-spin system under continuous resonant excitation with a radio-frequency (rf) field of arbitrary amplitude is demonstrated in solid-state 1H nuclear magnetic resonance (NMR) experiments on polycrystalline adamantane. Time-reversed evolution is accomplished with an rf pulse sequence that generates an effective nuclear spin Hamiltonian that includes both dipole-dipole coupling and rf interaction terms, with signs opposite to those in forward evolution. The amplitude of the effective continuous rf field is varied by varying the phases of rf pulses in the sequence. Experiments show echo-like NMR signals under time-reversed evolution after forward evolution to an apparent quasiequilibrium state under continuous rf excitation. Such echolike signals are inconsistent with the hypothesis of spin temperature in the rotating frame, according to which the approach to quasiequilibrium under continuous rf excitation is an irreversible process. The use of this time-reversed evolution in multiple quantum (MQ) NMR spectroscopy is also demonstrated. MQ NMR spectra obtained with increasing excitation times exhibit a partial confinement of nuclear spin order to zero- and one-quantum operators. This novel behavior is shown to be a consequence of energy conservation.

  1. 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.

  2. Measurement of the {sup 241}Am({gamma},n){sup 240}Am reaction in the giant dipole resonance region

    SciTech Connect

    Tonchev, A. P.; Howell, C. R.; Hutcheson, A.; Kwan, E.; Raut, R.; Rusev, G.; Tornow, W.; Hammond, S. L.; Huibregtse, C.; Kelley, J. H.; Kawano, T.; Vieira, D. J.; Wilhelmy, J. B.

    2010-11-15

    The photodisintegration cross section of the radioactive nucleus {sup 241}Am has been obtained using activation techniques and monoenergetic {gamma}-ray beams from the HI{gamma}S facility. The induced activity of {sup 240}Am produced via the {sup 241}Am({gamma},n) reaction was measured in the energy interval from 9 to 16 MeV utilizing high-resolution {gamma}-ray spectroscopy. The experimental data for the {sup 241}Am({gamma},n) reaction in the giant dipole resonance energy region are compared with statistical nuclear-model calculations.

  3. Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

    SciTech Connect

    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

  4. Optical properties of local surface plasmon resonance in Ag/ITO sliced nanosphere by the discrete dipole approximation

    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.

  5. Experimental verification of isotropic radiation from a coherent dipole source via electric-field-driven LC resonator metamaterials.

    PubMed

    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. PMID:24116780

  6. Study of the Pygmy Dipole Resonance in {sup 124}Sn by means of the ({alpha},{alpha}'{gamma}) reaction

    SciTech Connect

    Endres, J.; Zilges, A.; Pietralla, N.; Savran, D.; Sonnabend, K.; Harakeh, M. N.; Stoica, V.; Woertche, H.; Butler, P.; Herzberg, R. D.; Scheck, M.; Kruecken, R.; Popescu, L.; Harissopulos, S.; Lagoyannis, A.

    2009-01-28

    In recent years {alpha}-{gamma} coincidence experiments at 136 MeV incident energy on {sup 48}Ca, {sup 140}Ce, {sup 138}Ba and {sup 124}Sn were performed at the KVI in Groningen to study the isospin character of electric dipole excitations below the particle threshold, frequently called Pygmy Dipole Resonance (PDR). An array of HPGe {gamma}-detectors has been used in coincidence with the Big-Bite Spectrometer (BBS) and a resolution of about 10 keV in the {gamma}-ray energy has been achieved. The results show that the excitation patterns of the PDR in the ({alpha},{alpha}') reaction seem to differ significantly from results obtained in Nuclear Resonance Fluorescence (NRF)({gamma},{gamma}') measurements. The PDR, which until now has been assigned to one excitation mode, splits up into two parts: One that is excited in ({alpha},{alpha}'{gamma}) and ({gamma},{gamma}') reactions (denoting a dominant isoscalar character), and one that is only excited in ({gamma},{gamma}')(denoting a dominant isovector character). This indicates that two different excitation mechanisms produce these low-lying E1 excitations [1], The preliminary results of the latest measurements on the N = 82 nucleus {sup 138}Ba and the Z = 50 nucleus {sup 124}Sn show that this break up into two parts is a common feature of the PDR in semi-magic nuclei.

  7. Study of the Pygmy Dipole Resonance in 124Sn by means of the (α,α'γ) reaction

    NASA Astrophysics Data System (ADS)

    Endres, J.; Zilges, A.; Pietralla, N.; Savran, D.; Sonnabend, K.; Harakeh, M. N.; Stoica, V.; Wörtche, H.; Butler, P.; Herzberg, R. D.; Scheck, M.; Krü; cken, R.; Popescu, L.; Harissopulos, S.; Lagoyannis, A.

    2009-01-01

    In recent years α-γ coincidence experiments at 136 MeV incident energy on 48Ca, 140Ce, 138Ba and 124Sn were performed at the KVI in Groningen to study the isospin character of electric dipole excitations below the particle threshold, frequently called Pygmy Dipole Resonance (PDR). An array of HPGe γ-detectors has been used in coincidence with the Big-Bite Spectrometer (BBS) and a resolution of about 10 keV in the γ-ray energy has been achieved. The results show that the excitation patterns of the PDR in the (α,α') reaction seem to differ significantly from results obtained in Nuclear Resonance Fluorescence (NRF) (γ,γ') measurements. The PDR, which until now has been assigned to one excitation mode, splits up into two parts: One that is excited in (α,α'γ) and (γ,γ') reactions (denoting a dominant isoscalar character), and one that is only excited in (γ,γ') (denoting a dominant isovector character). This indicates that two different excitation mechanisms produce these low-lying E1 excitations [1], The preliminary results of the latest measurements on the N = 82 nucleus 138Ba and the Z = 50 nucleus 124Sn show that this break up into two parts is a common feature of the PDR in semi-magic nuclei.

  8. Probing nuclear shapes close to the fission limit with the giant dipole resonance in {sup 216}Rn

    SciTech Connect

    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 {approx_equal}1 MeV was found to be larger than that at T=0 MeV and to be approximately constant as a function of spin. The measured width value of 7 MeV is found to be consistent with the predictions based on calculations of the nuclear shape distribution using the newest approach for the treatment of the fission barrier within the liquid drop model. The present study is the first investigation of the giant dipole resonance width from the fusion-evaporation decay channel in this nuclear mass range.

  9. Neutron Resonance Parameters and Covariance Matrix of 239Pu

    SciTech Connect

    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.

  10. Towards in vivo imaging of intramolecular fluorescence resonance energy transfer parameters.

    PubMed

    Gaind, Vaibhav; Webb, Kevin J; Kularatne, Sumith; Bouman, Charles A

    2009-08-01

    Fluorescence resonance energy transfer (FRET) is a nonradiative energy transfer process based on dipole-dipole interaction between donor and acceptor fluorophores that are spatially separated by a distance of a few nanometers. FRET has proved to be of immense value in the study of cellular function and the underlying cause of disease due to, for example, protein misfolding (of consequence in Alzheimer's disease). The standard parameterization in intramolecular FRET is the lifetime and yield, which can be related to the donor-acceptor (DA) distance. FRET imaging has thus far been limited to in vitro or near-surface microscopy because of the deleterious effects of substantial scatter. We show that it is possible to extract the microscopic FRET parameters in a highly scattering environment by incorporating the FRET kinetics of an ensemble of DA molecules connected by a flexible or rigid linker into an optical diffusion tomography (ODT) framework. We demonstrate the efficacy of our approach for extracting the microscopic DA distance through simulations and an experiment using a phantom with scattering properties similar to tissue. Our method will allow the in vivo imaging of FRET parameters in deep tissue, and hence provide a new vehicle for the fundamental study of disease. PMID:19649115

  11. Electron paramagnetic resonance line shifts and line shape changes due to heisenberg spin exchange and dipole-dipole interactions of nitroxide free radicals in liquids 8. Further experimental and theoretical efforts to separate the effects of the two interactions.

    PubMed

    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

  12. 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.

  13. Reflection and transmission properties of a metasurface composed of resonant loaded wire dipoles.

    PubMed

    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. PMID:27411153

  14. Pt-Au Triangular Nanoprisms with Strong Dipole Plasmon Resonance for Hydrogen Generation Studied by Single-Particle Spectroscopy.

    PubMed

    Lou, Zaizhu; Fujitsuka, Mamoru; Majima, Tetsuro

    2016-06-28

    Three anisotropic Pt-covered, Pt-edged, and Pt-tipped Au triangular nanoprisms (TNPs) were prepared by controlling the overgrowth of Pt as photocatalysts for H2 generation. With strong electric field and more interface for the hot electrons transfer, the H2 generation rate of Pt-edged Au TNPs was 3 and 5 times higher than those of Pt-tipped and Pt-covered Au TNPs. Single-particle photoluminescence (PL) spectra and finite-difference-time-domain (FDTD) simulations demonstrated that dipole surface plasmon resonance (DSPR) of Au TNPs enhanced the hot electrons transfer from Au to Pt leading to H2 generation. SPR bands of Au TNPs depending on the size play an important role on the photocatalytic activity of Pt-edged Au TNPs. PMID:27212221

  15. Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

    SciTech Connect

    MJ Trbovich; DP Barry; RE Slovacck; Y Danon; RC Block; JA Burke; NJ Drindak; G Leinweber; RV Ballad

    2004-10-13

    The focus of this work is to determine 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. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically-enriched liquid samples. The liquid samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY [1] and INTER [2] codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

  16. Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments

    SciTech Connect

    Trbovich, Michael J.; Barry, Devin P.; Burke, John A.; Drindak, Noel J.; Leinweber, Greg; Ballad, Robert V.; Slovacek, Rudy E.; Danon, Yaron; Block, Robert C.

    2005-05-24

    The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions.Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. 6Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen-section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8-eV doublet without saturation.Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. 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 previously published values; however the calculated elemental hafnium resonance integral changed very little.

  17. A resonant scanning dipole-antenna probe for enhanced nanoscale imaging.

    PubMed

    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. PMID:24124987

  18. Description of the dipole giant resonance in heavy and superheavy nuclei within Skyrme random-phase approximation

    SciTech Connect

    Kleinig, W.; Nesterenko, V. O.; Kvasil, J.; Vesely, P.; Reinhard, P.-G.

    2008-10-15

    The E1(T=1) isovector dipole giant resonance (GDR) in heavy and superheavy deformed nuclei is analyzed over a sample of 18 rare-earth nuclei, four actinides, and three chains of superheavy elements (Z=102, 114, and 120). The basis of the description is the self-consistent separable random-phase approximation (SRPA) using the Skyrme force SLy6. The model well reproduces the experimental data in the rare-earth and actinide regions. The trend of the resonance peak energies follows the estimates from collective models, showing a bias to the volume mode for the rare-earth isotopes and a mix of volume and surface modes for actinides and superheavy elements. The widths of the GDR are mainly determined by the Landau fragmentation, which in turn is found to be strongly influenced by deformation. A deformation splitting of the GDR can contribute to about one-third of the width, and about 1 MeV further broadening can be associated with mechanisms beyond the SRPA description (e.g., escape widths and coupling with complex configurations)

  19. Collisional excitation of the highly excited hydrogen atoms in the dipole form of the semiclassical impact parameter and Born approximations

    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.

  20. Heavy ion Coulomb excitation and gamma decay studies of the one and two phonon giant dipole resonances in {sup 208}Pb and {sup 209}Bi

    SciTech Connect

    Mueller, P.E.; Beene, J.R.; Bertrand, F.E.

    1993-12-01

    Projectile -- photon coincidences were measured for the scattering of an 80 MeV/nucleon {sup 64}Zn beam from {sup 208}Pb and {sup 209}Bi targets at the GANIL heavy ion accelerator facility. Projectile-like particles between 0.5{degrees} and 4.5{degrees} relative to the incident beam direction were detected in the SPEG energy loss spectrometer where their momentum, charge, and mass were determined. Photons were detected in the BaF{sub 2} scintillation detector array TAPS. Light charged particles produced in the reaction were detected in the KVI Forward Wall. The analysis of the data acquired in this experiment is focused on three different phenomena: (1) the two phonon giant dipole resonance, (2) time dependence of the decay of the one phonon giant dipole resonance, and (3) giant resonance strength in projectile nuclei.

  1. Bound free electron-positron pair production accompanied by giant dipole resonances

    SciTech Connect

    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.

  2. 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.

  3. Theory and computation of nuclear magnetic resonance parameters.

    PubMed

    Vaara, Juha

    2007-10-28

    The art of quantum chemical electronic structure calculation has over the last 15 years reached a point where systematic computational studies of magnetic response properties have become a routine procedure for molecular systems. One of their most prominent areas of application are the spectral parameters of nuclear magnetic resonance (NMR) spectroscopy, due to the immense importance of this experimental method in many scientific disciplines. This article attempts to give an overview on the theory and state-of-the-art of the practical computations in the field, in terms of the size of systems that can be treated, the accuracy that can be expected, and the various factors that would influence the agreement of even the most accurate imaginable electronic structure calculation with experiment. These factors include relativistic effects, thermal effects, as well as solvation/environmental influences, where my group has been active. The dependence of the NMR spectra on external magnetic and optical fields is also briefly touched on. PMID:17925967

  4. 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

  5. Quasistatic dipole in magnetized plasma in resonance frequency band. Response of the receiving antenna, and charge distribution on the antenna wire

    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.

  6. Evaluation of 238U Resonance Parameters from 0 to 20 keV

    NASA Astrophysics Data System (ADS)

    Derrien, H.; Courcelle, A.; Leal, L. C.; Larson, N.; Santamarina, A.

    2005-05-01

    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.

  7. Evaluation of 238U Resonance Parameters from 0 to 20 keV

    SciTech Connect

    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.

  8. Parameter-Induced Stochastic Resonance of Weak Periodic Signal Excitation with α Stable Noise

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Kou, Jie; Jiao, Shang-Bin

    In view of the nonlinear bistable system, this paper studied the parameter-induced stochastic resonance phenomenon of low-frequency weak signal excitation under α stable noise environment, and explored the action laws of the α stable noise distribution parameters α, β, μ, σ and the bistable system parameters a, b on stochastic resonance effect. The results show that in different α stable noise, adjusting the bistable system parameters can induce stochastic resonance; Moreover, when a(or b) is fixed, the intervals of b(or a) which can induce stochastic resonance are multiple and don't change with any α stable distribution parameter. Further, by combining with the parameter compensation method for researching on high-frequency weak signal, the same action laws as the low-frequency signal are got. The conclusions are significant for using parameter-induced stochastic resonance principle in weak signal detection in the abnormal diffusion dynamical system.

  9. Modification of piezoelectric vibratory gyroscope resonator parameters by feedback control.

    PubMed

    Loveday, P W; Rogers, C A

    1998-01-01

    A method for analyzing the effect of feedback control on the dynamics of piezoelectric resonators used in vibratory gyroscopes has been developed. This method can be used to determine the feasibility of replacing the traditional mechanical balancing operations, used to adjust the resonant frequency, by displacement feedback and for determining the velocity feedback required to produce a particular bandwidth. Experiments were performed on a cylindrical resonator with discrete piezoelectric actuation and sensing elements to demonstrate the principles. Good agreement between analysis and experiment was obtained, and it was shown that this type of resonator could be balanced by displacement feedback. The analysis method presented also is applicable to micromachined piezoelectric gyroscopes. PMID:18244281

  10. The far-infrared laser magnetic resonance spectrum of the SiH radical and determination of ground state parameters

    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.

  11. Microstrip monpulse dipole array

    NASA Astrophysics Data System (ADS)

    Miccioli, W.; Toth, J.; Sa, N.; Lewis, M.

    1985-01-01

    The development of a microstrip radiating aperture utilizing multiple microstrip dipole radiators fed by a resonant feed configuration is described. This array combines an efficient capacitively coupled radiator feeding mechanism with a planar power divider configuration to achieve an extremely thin, lightweight antenna aperture. Linear array dipole matching theory and radiator bandwidth improvement techniques are also described. A quadrant based microstrip monopulse antenna was constructed. Experimental data from this array, its subassemblies and individual components are presented and compared to analytical predictions.

  12. Infrared and far-infrared laser magnetic resonance spectroscopy of the GeH radical - Determination of ground state parameters

    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.

  13. Low-energy tail of the giant dipole resonance in Mo98 and Mo100 deduced from photon-scattering experiments

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Schwengner, R.; Dönau, F.; Erhard, M.; Grosse, E.; Junghans, A. R.; Kosev, K.; Schilling, K. D.; Wagner, A.; Bečvář, F.; Krtička, M.

    2008-06-01

    Dipole-strength distributions in the nuclides Mo98 and Mo100 up to the neutron-separation energies have been studied in photon-scattering experiments at the bremsstrahlung facility of the Forschungszentrum Dresden-Rossendorf. To determine the dipole-strength distributions up to the neutron-emission thresholds, statistical methods were developed for the analysis of the measured spectra. The measured spectra of scattered photons were corrected for detector response and atomic background by simulations using the code GEANT3. Simulations of γ-ray cascades were performed to correct the intensities of the transitions to the ground state for feeding from higher-lying levels and to determine their branching ratios. The photoabsorption cross sections obtained for Mo98 and Mo100 from the present (γ,γ') experiments are combined with (γ,n) data from literature, resulting in a photoabsorption cross section covering the range from 4 to about 15 MeV of interest for network calculations in nuclear astrophysics. Novel information about the low-energy tail of the giant dipole resonance and its energy dependence is derived. The photoabsorption cross sections deduced from the present photon-scattering experiments are compared with existing data from neutron capture and He3-induced reactions.

  14. Electron paramagnetic resonance investigation of photosynthetic reaction centers from Rhodobacter sphaeroides R-26 in which Fe2+ was replaced by Cu2+. Determination of hyperfine interactions and exchange and dipole-dipole interactions between Cu2+ and QA-.

    PubMed Central

    Calvo, R; Passeggi, M C; Isaacson, R A; Okamura, M Y; Feher, G

    1990-01-01

    We report electron paramagnetic resonance (EPR) experiments in frozen solutions of unreduced and reduced photosynthetic reaction centers (RCs) from Rhodobacter sphaeroides R-26 in which Fe2+ has been chemically replaced by the isotope 65Cu2+. Samples in which the primary quinone acceptor QA is unreduced (Cu2+QA:RCs) give a powder EPR spectrum typical for Cu2+ having axial symmetry, corresponding to a d(x2 - y2) ground state orbital, with g values g parallel = 2.314 +/- 0.001 and g perpendicular = 2.060 +/- 0.003. The spectrum shows a hyperfine structure for the nuclear spin of copper (65I = 3/2) with A parallel = (-167 +/- 1) x 10(-4) cm-1 and /A perpendicular/ = (16 +/- 2) x 10(-4) cm-1, and hyperfine couplings with three nitrogen ligands. This has been verified in samples containing the naturally occurring 14N isotope (l = 1), and in samples where the nitrogen ligands to copper were replaced by the isotope 15N (l = 1/2). We introduce a model for the electronic structure at the position of the metal ion which reflects the recently determined three-dimensional structure of the RCs of Rb. sphaeroides (Allen, J. P., G. Feher, T. O. Yeates, H. Komiya, and D. C. Rees. 1987. Proc. Natl. Acad. Sci. USA. 84:5730: Allen, J. P., G. Feher, T. O. Yeates, H. Komiya, and D. C. Rees. 1988. Proc. Natl. Acad. Sci. USA, 85:8487) as well as our EPR results. In this model the copper ion is octahedrally coordinated to three nitrogens from histidine residues and to one carboxylate oxygen from a glutamic acid, forming a distorted square in the plane of the d(x2 = y2) ground state orbital. It is also bound to a nitrogen of another histidine and to the other carboxylate oxygen of the same glutamic acid residue, in a direction approximately normal to this plane. The EPR spectrum changes drastically when the quinone acceptor QA is chemically reduced (Cu2+QA-:RCs); the change is due to the exchange and dipole-dipole interactions between the Cu2+ and QA- spins. A model spin Hamiltonian

  15. Photoresponse of 60Ni below 10-MeV excitation energy: Evolution of dipole resonances in fp-shell nuclei near N=Z

    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.

  16. Benefits of using multi-component transmitter-receiver systems for determining geometrical parameters of a dipole conductor from single-line anomalies

    NASA Astrophysics Data System (ADS)

    Desmarais, Jacques K.; Smith, Richard S.

    2016-03-01

    We show the advantages of using multi-component transmitter-receiver systems for determining the geometry of a compact planar target whose electromagnetic response can be approximated by a dipole. Our approach is based on a modified version of an algorithm that we previously published using a single-component (vertical) transmitter. Tests on synthetic models reveal that single transmitter systems are unable to resolve the orientation of a dipole conductor that approaches axial symmetry with respect to the traverse line. This occurs as a result of lack of a noticeable y-component anomaly, where the y-component is oriented transverse to the flight-line direction. For a plate-like conductor, axial symmetry equates to being at a small offset and having a strike parallel or perpendicular to the traverse line. Here, the term `offset' is used to denote the lateral distance from the centre of the conductor to the flight line. The ambiguities can be resolved through measuring specific components of a multi-component transmitter-receiver system; namely, Rxz and Rzz with one of Rxy, Ryy, Rzy, Ryx and Ryz, where the first letter denotes the orientation of the transmitter and the second letter denotes the orientation of the receiver. However, for the case of a MEGATEM system geometry, measuring Rzx, Rzz and Ryx is most suitable for determining the geometry of conductors striking nearly perpendicular or parallel, and at small offset to the traverse line. The minimum system capable of determining the correct geometrical parameters of a dipole conductor for the small-offset symmetric case would therefore consist of a two-component (y- and z-directed) transmitter, as well as a two component (x- and z-directed) receiver. Tests on line 15701 of the MEGATEM survey in Chibougamau, Quebec, confirm the inability of single-transmitter systems to determine geometrical parameters of a dipole conductor for the case where y-component data is unavailable.

  17. Tevatron AC dipole system

    SciTech Connect

    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.

  18. Test of the Universality of the Three-Body Efimov Parameter at Narrow Feshbach Resonances

    NASA Astrophysics Data System (ADS)

    Roy, Sanjukta; Landini, Manuele; Trenkwalder, Andreas; Semeghini, Giulia; Spagnolli, Giacomo; Simoni, Andrea; Fattori, Marco; Inguscio, Massimo; Modugno, Giovanni

    2013-08-01

    We measure the critical scattering length for the appearance of the first three-body bound state, or Efimov three-body parameter, at seven different Feshbach resonances in ultracold K39 atoms. We study both intermediate and narrow resonances, where the three-body spectrum is expected to be determined by the nonuniversal coupling of two scattering channels. Instead, our observed ratio of the three-body parameter with the van der Waals radius is approximately the same universal ratio as for broader resonances. This unexpected observation suggests the presence of a new regime for three-body scattering at narrow resonances.

  19. 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.

  20. 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.

  1. Observation of the 5 p3 /2→6 p3 /2 electric-dipole-forbidden transition in atomic rubidium using optical-optical double-resonance spectroscopy

    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.

  2. Nuclear Magnetic Resonance Structure of a Major Lens Protein, Human γC-Crystallin: Role of the Dipole Moment in Protein Solubility.

    PubMed

    Dixit, Karuna; Pande, Ajay; Pande, Jayanti; Sarma, Siddhartha P

    2016-06-01

    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. PMID:27187112

  3. Aperiodic signals processing via parameter-tuning stochastic resonance in a photorefractive ring cavity

    SciTech Connect

    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.

  4. SAMDIST: A Computer Code for Calculating Statistical Distributions for R-Matrix Resonance Parameters

    SciTech Connect

    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.

  5. SAMDIST: A computer code for calculating statistical distributions for R-matrix resonance parameters

    SciTech Connect

    Leal, L.C.; Larson, N.M.

    1995-09-01

    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.

  6. Optimized tapered dipole nanoantenna as efficient energy harvester.

    PubMed

    El-Toukhy, Youssef M; Hussein, Mohamed; Hameed, Mohamed Farhat O; Heikal, A M; Abd-Elrazzak, M M; Obayya, S S A

    2016-07-11

    In this paper, a novel design of tapered dipole nanoantenna is introduced and numerically analyzed for energy harvesting applications. The proposed design consists of three steps tapered dipole nanoantenna with rectangular shape. Full systematic analysis is carried out where the antenna impedance, return loss, harvesting efficiency and field confinement are calculated using 3D finite element frequency domain method (3D-FEFD). The structure geometrical parameters are optimized using particle swarm algorithm (PSO) to improve the harvesting efficiency and reduce the return loss at wavelength of 500 nm. A harvesting efficiency of 55.3% is achieved which is higher than that of conventional dipole counterpart by 29%. This enhancement is attributed to the high field confinement in the dipole gap as a result of multiple tips created in the nanoantenna design. Furthermore, the antenna input impedance is tuned to match a wide range of fabricated diode based upon the multi-resonance characteristic of the proposed structure. PMID:27410898

  7. Inter-channel effects in monosolvated atomic iodide cluster anion detachment: Correlation of the anisotropy parameter with solvent dipole moment

    NASA Astrophysics Data System (ADS)

    Mbaiwa, Foster; Dao, Diep; Holtgrewe, Nicholas; Lasinski, Joshua; Mabbs, Richard

    2012-03-01

    Photoelectron imaging results are presented for I-.X cluster anions (X = CO2, C4H5N [pyrrole], (CH3)2CO, CH3NO2). The available detachment channels are labeled according to the neutral iodine atom states produced (channel I ≡ 2P3/2 and channel II ≡ 2P1/2). At photon energies in the vicinity of the channel II threshold these data are compared to previously reported results for I-.X (X = CH3CN, CH3Cl, CH3Br, and H2O). In particular, these results show a strong connection between the dipole moment of the solvent molecule and the behavior of the channel I photoelectron angular distributions in this region, which is consistent with an electronic autodetachment process. The evolution of the channel II:channel I branching ratios in this excitation regime supports this contention.

  8. Resonance Parameters of the Rho-Meson from Lattice QCD

    SciTech Connect

    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.

  9. Resonance parameters of the {rho} meson from lattice QCD

    SciTech Connect

    Feng Xu; Jansen, Karl; Renner, Dru B.

    2011-05-01

    We perform a nonperturbative 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 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.

  10. 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.

  11. Deep-tissue imaging of intramolecular fluorescence resonance energy-transfer parameters.

    PubMed

    Gaind, Vaibhav; Kularatne, Sumith; Low, Philip S; Webb, Kevin J

    2010-05-01

    We demonstrate the in vivo reconstruction of all fluorescence resonance energy transfer (FRET) parameters, including the nanometer donor-acceptor distance, in a mouse. The FRET chemical targets cancer cells, and on internalization, the acceptor is released, in lieu of a targeted anticancer drug in chemotherapy. Our method provides a new vehicle for studying disease by imaging FRET parameters in deep tissue. PMID:20436553

  12. Resonance parameters based analysis for metallic thickness optimization of a bimetallic plasmonic structure

    NASA Astrophysics Data System (ADS)

    Bera, Mahua; Banerjee, Jayeta; Ray, Mina

    2014-02-01

    Metallic film thickness optimization in mono- and bimetallic plasmonic structures has been carried out in order to determine the correct device parameters. Different resonance parameters, such as reflectivity, phase, field enhancement, and the complex amplitude reflectance Argand diagram (CARAD), have been investigated for the proposed optimization procedure. Comparison of mono- and bimetallic plasmonic structures has been carried out in the context of these resonance parameters with simultaneous angular and spectral interrogation. Differential phase analysis has also been performed and its application to sensing has been discussed along with a proposed interferometric set-up.

  13. Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium

    SciTech Connect

    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

  14. Critical behavior of isotropic three-dimensional systems with dipole-dipole interactions

    SciTech Connect

    Belim, S. M.

    2013-06-15

    The critical behavior of Heisenberg magnets with dipole-dipole interactions near the line of second-order phase transitions directly in three-dimensional space is investigated in terms of a field-theoretic approach. The dependences of critical exponents on the dipole-dipole interaction parameter are derived. Comparison with experimental facts is made.

  15. Efimov Resonance and Three-Body Parameter in a Lithium-Rubidium Mixture.

    PubMed

    Maier, R A W; Eisele, M; Tiemann, E; Zimmermann, C

    2015-07-24

    We study collisional heating in a cold ^{7}Li-^{87}Rb mixture near a broad Feshbach resonance at 661 G. At the high field slope of the resonance, we find an enhanced three-body recombination rate that we interpret as a heteronuclear Efimov resonance. With improved Feshbach spectroscopy of two further resonances, a model for the molecular potentials has been developed that now consistently explains all known Feshbach resonances of the various Li-Rb isotope mixtures. The model is used to determine the scattering length of the observed Efimov state. Its value of -1870a_{0} Bohr radii supports the currently discussed assumption of universality of the three-body parameter also in heteronuclear mixtures. PMID:26252682

  16. Radio frequency spectral characterization and model parameters extraction of high Q optical resonators.

    PubMed

    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

  17. Radio frequency spectral characterization and model parameters extraction of high Q optical resonators

    NASA Astrophysics Data System (ADS)

    Abdallah, Zeina; Boucher, Yann G.; Fernandez, Arnaud; Balac, Stéphane; Llopis, Olivier

    2016-06-01

    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.

  18. Radio frequency spectral characterization and model parameters extraction of high Q optical resonators

    PubMed Central

    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

  19. Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium

    SciTech Connect

    Leinweber, G.; Burke, J.A.; Knox, H.D.; Drindak, N.J.; Mesh, D.W.; Haines, W.T.; Ballad, R.V.; Block, R.C.; Slovacek, R.E.; Werner, C.J.; Trbovich, M.J.; Barry, D.P.; Sato, T.

    2002-09-15

    The purpose of the present work is to measure the neutron cross sections of samarium accurately. 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-m flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-m 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 multilevel 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 (RI) 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 RI to include the strong 0.1-eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with ENDF

  20. [Effect of the evaluation parameter on sensitivity of resonance thrombography of thrombocytopenia in dogs].

    PubMed

    Adamik, A; Mischke, R

    1998-11-01

    Based on 109 blood samples taken from 36 dogs suffering from thrombocytopenia resonance thrombography with the resonance thrombograph RTG 801 (von Hoerner und Sulger Electronic GmbH, Schwetzingen; manufacturer: Fresenius AG, Bad Homburg) was distinctly more sensitive and more closely correlated to the platelet count using an optimized parameter of the resonance thrombogramm (RTG) in comparison to usual parameters. Nevertheless, clinical requirements regarding samples with platelet counts > 25,000/microliter were not fulfilled. Out of 13 samples with reduced platelet count and simultanous extended capillary bleeding time, depending on the used parameter a maximum of 9 samples could be detected as pathological by the RTG. The normal RTG in part of the cases with clearly altered primary haemostasis contrasts to the exclusive use of RTG in the screening of thrombocytopenia in dogs. PMID:9857562

  1. Determination of Resonance Parameters and their Covariances from Neutron Induced Reaction Cross Section Data

    SciTech Connect

    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.

  2. Electric-dipole moment of CaF by molecular-beam, laser-rf, double-resonance study of Stark splittings

    SciTech Connect

    Childs, W.J.; Goodman, L.S.; Nielsen, U.; Pfeufer, V.

    1984-01-01

    The electronic structure of diatomic molecules is much more complex for open-shell sytems (radicals) than for the normal closed-shell systems, and the development of an adequate theoretical understanding will require a substantial upgrading of experimental knowledge in both quality and quantity. The alkaline-earth monohalide family of radicals, with only a single electron outside closed-shell cores, would appear to be a logical starting point for such studies, and there has been a great increase in work in this area in the last few years in spite of the special difficulties of working with free radicals. As the work of measuring the vibrational and rotational structure of the electronic states has become more complete, attention has turned to study of the much weaker spin-rotation and hyperfine interactions. Within the last three years, these interactions have been studied systematically at high precision in the calcium monohalide family with the molecular-beam, laser-rf double-resonance technique. The same method has now been modified and extended to make possible measurement of the electric-dipole moments of these molecules through observation of the Stark splittings of radiofrequency transitions. It is hoped that when considered together, the several types of data will make it possible to understand the ground-state electronic wave functions of these molecules at least qualitatively. 2 figures.

  3. Study of the Pygmy Dipole Resonance in (p,p'γ) and (d,pγ) experiments with SONIC@HORUS

    NASA Astrophysics Data System (ADS)

    Pickstone, S. G.; Derya, V.; Hennig, A.; Mayer, J.; Spieker, M.; Weinert, M.; Wilhelmy, J.; Zilges, A.

    2015-05-01

    Last year, the new silicon-detector array SONIC with up to 8 silicon-detector positions was installed inside the existing γ-ray spectrometer HORUS consisting of 14 HPGe detectors. The combined setup SONIC@HORUS allows for a coincident detection of γ-rays and light charged particles in the exit channel of inelastic scattering and transfer reactions. As a first physics case, the Pygmy Dipole Resonance (PDR) in 92Mo has been investigated in a (p,p'γ) experiment at Ep = 10.5 MeV. Since specific excitation energy can be chosen offline in the coincidence data, the sensitivity to weak decay branchings of PDR states is increased. Additionally, a second reaction mechanism for the excitation of PDR states has been tested with the new setup. In a 119Sn(d,pγ) transfer reaction at Ed = 8.5 MeV, PDR states in 120Sn could be excited. Since this one-neutron transfer reaction is sensitive to the neutron single-particle structure, it could reveal new information on the microscopic structure of the PDR.

  4. 'Coulomb' description of basic relaxation parameters of isobar analog and charge-exchange giant monopole resonances

    SciTech Connect

    Gorelik, M. L.; Rykovanov, V. S.; Urin, M. G.

    2010-12-15

    Within a semimicroscopic approach, basic relaxation parameters of the isobaric analog resonance and of the charge-exchange giant monopole resonance, which is an overtone of the isobaric analog resonance, are interpreted in terms of the mean Coulomb field of a nucleus. The continuum version of the random-phase approximation, allowance for an approximate isospin conservation in nuclei in an explicit form, and a phenomenological description of the fragmentation effect are basic ingredients of the approach used. The aforementioned parameters were calculated for a number of magic and near-magic nuclei by using a partly self-consistent phenomenological nuclear mean field and the isovector part of the Landau-Migdal interaction in the particle-hole channel. The results of the calculations are compared with corresponding experimental data.

  5. Controlling the Radiation Parameters of a Resonant Medium Excited by a Sequence of Ultrashort Superluminal Pulses

    NASA Astrophysics Data System (ADS)

    Arkhipov, R. M.; Arkhipov, M. V.; Belov, P. A.; Babushkin, I.; Tolmachev, Yu. A.

    2016-03-01

    We investigate the possibility of controlling the radiation parameters of a spatially periodic one-dimensional medium consisting of classical harmonic oscillators by means of a sequence of ultrashort pulses that propagate through the medium with a superluminal velocity. We show that, in the spectrum of the transient process, in addition to the radiation at a resonant frequency of oscillators, new frequencies arise that depend on the period of the spatial distribution of the oscillator density, the excitation velocity, and the angle of observation. We have examined in detail the case of excitation of the medium by a periodic sequence of ultrashort pulses that travel with a superluminal velocity. We show that it is possible to excite oscillations of complex shapes and to control the radiation parameters of the resonant medium by changing the relationship between the pulse repetition rate, the medium resonant frequency, and the new frequency.

  6. Dynamic dipoles

    NASA Astrophysics Data System (ADS)

    Griffiths, David J.

    2011-08-01

    We study stationary but time-dependent ideal (point) electric and magnetic dipoles, both the conventional type consisting of electric charges and currents and the hypothetical kind composed of magnetic monopoles and their currents. We derive their potentials and fields, and calculate the energy, momentum, and angular momentum they radiate.

  7. Numerical Based Linear Model for Dipole Magnets

    SciTech Connect

    Li,Y.; Krinsky, S.; Rehak, M.

    2009-05-04

    In this paper, we discuss an algorithm for constructing a numerical linear optics model for dipole magnets from a 3D field map. The difference between the numerical model and K. Brown's analytic approach is investigated and clarified. It was found that the optics distortion due to the dipoles' fringe focusing must be properly taken into account to accurately determine the chromaticities. In NSLS-II, there are normal dipoles with 35-mm gap and dipoles for infrared sources with 90-mm gap. This linear model of the dipole magnets is applied to the NSLS-II lattice design to match optics parameters between the DBA cells having dipoles with different gaps.

  8. On the Methodology to Calculate the Covariance of Estimated Resonance Parameters

    SciTech Connect

    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.

  9. Evaluation of Silicon Neutron Resonance Parameters in the Energy Range Thermal to 1800 keV

    SciTech Connect

    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.

  10. 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.

  11. Dipole-dipole interaction between rubidium Rydberg atoms

    SciTech Connect

    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.

  12. Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure

    SciTech Connect

    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.

  13. Trojan resonant dynamics, stability, and chaotic diffusion, for parameters relevant to exoplanetary systems

    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

  14. Observation of Stueckelberg oscillations in dipole-dipole interactions

    SciTech Connect

    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.

  15. Changes of Schumann resonance parameters during the solar proton event of 14 July 2000

    NASA Astrophysics Data System (ADS)

    Roldugin, V. C.; Maltsev, Y. P.; Vasiljev, A. N.; Shvets, A. V.; Nikolaenko, A. P.

    2003-03-01

    The ELF measurements in Russian observatories Lovozero (the Kola Peninsula) and Lekhta (Karelija) during the solar proton event of 14 July 2000 show the decrease of frequencies of the first and second Schumann resonance modes of ˜0.4 Hz and the increase of the first-mode bandwidth from 0.8 to 1.5 Hz. The solar X-ray burst, preceding the proton precipitation, is accompanied by the increase of the first-mode frequency. Approximate formulas for frequencies and qualities of the two first modes are found for a two-layer model of the Schumann resonator (SR). The changes of the SR parameters are a response of the Earth-ionosphere resonator to large-scale disturbances of the polar ionosphere.

  16. Broad-band UHF dipole array

    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.

  17. Parameter-induced stochastic resonance based on spectral entropy and its application to weak signal detection

    SciTech Connect

    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.

  18. sup 56 Fe resonance parameters for neutron energies up to 850 keV

    SciTech Connect

    Perey, C.M.; Perey, F.G.; Harvey, J.A.; Hill, N.W.; Larson, N.M.

    1990-12-01

    High-resolution neutron measurements for {sup 56}Fe-enriched iron targets were made at the Oak Ridge Electron Linear Accelerator (ORELA) in transmission below 20 MeV and in differential elastic scattering below 5 MeV. Transmission measurements were also performed with a natural iron target below 160 keV. The transmission data were analyzed from 5 to 850 keV with the multilevel R-matrix code SAMMY which uses Bayes' theorem for the fitting process. This code provides energies and neutron widths of the resonances inside the 5- to 850-keV energy region, as well as possible parameterization for resonances external to the analyzed region to describe the smooth cross section from a few eV to 850 keV. The resulting set of resonance parameters yields the accepted values for the thermal total and capture cross sections. The differential elastic-scattering data at several scattering angles were compared to theoretical calculations from 40 to 850 keV using the R-matrix code RFUNC based on the Blatt-Biedenharn formalism. Various combinations of spin and parity were tried to predict cross sections for the well defined {ell} > 0 resonances; comparison of these predictions with the data allowed us to determine the most likely spin and parity assignments for these resonances. The results of a capture data analysis by Corvi et al. (COR84), from 2 to 350 keV, were combined with our results to obtain the radiation widths of the resonances below 350 keV observed in transmission, capture, and differential elastic-scattering experiments.

  19. Carbon nanotube vee dipole antennas for optical applications

    NASA Astrophysics Data System (ADS)

    Khaleel, Haider R.; Al-Rizzo, Hussain M.; Elwi, Taha A.; Rucker, Daniel

    2009-08-01

    This paper investigates the radiation characteristics of a Vee dipole antenna operating in the near infra-red and optical frequency regimes. Antenna properties, such as far-field radiation patterns, coupling coefficient, measured by the scattering parameter S11, and directivity are provided. The resonance and directivity behavior of the optical Vee dipole, which is based on Multi-Wall Carbon Nano Tube (MWCNT), are investigated by varying the dipole length in order to exploit the effective operating frequency in the near infra-red range (~120 to 400 THz) and the visible light range (~400- 750 THz). Moreover, a parametric study aimed at optimizing the antenna directivity is performed by varying the angle between the two arms of the dipole using CST Microwave Studio simulation software which is based on the Finite Integration Technique (FIT). The proposed antenna achieved a directivity 3.767 dB higher than the traditional dipole in the visible regime while maintaining the same directivity in the near infrared regime.

  20. Evaluation of silicon neutron resonance parameters in the thermal to 1800 keV energy range.

    PubMed

    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. PMID:16381717

  1. Towards coherent manipulation of the ground states of single cesium atom confined in a microscopic far-off-resonance optical dipole trap

    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.

  2. A novel parameter-induced stochastic resonance phenomena in fractional Fourier domain

    NASA Astrophysics Data System (ADS)

    Lin, Lifeng; Wang, Huiqi; Lv, Wangyong; Zhong, Suchuan

    2016-08-01

    The parameter-induced stochastic resonance (SR) phenomenon in a novel self-adaptive dynamical system driven by linear frequency modulated (LFM) signal and additive noise is considered from the view of the signal-to-noise ratio (SNR). It is found that the dynamical system can be perfectly analyzed by equivalently transforming it into a traditional first-order linear dynamical system driven by periodic signal and additive noise in fractional Fourier transform (FrFT) domain with an optimal rotated angle, and the theoretical analysis and simulation results show that output SNR exhibits the SR behavior when it is plotted as a function of the system parameter. Furthermore, the optimal value of adjusted parameter is obtained, and the possible area of SNR gain is theoretically determined only by center-frequency and modulated frequency of the driving LFM signal.

  3. Parameter optimization analysis to minimize the polarization error in a localized thermal tunable fiber ring resonator gyro.

    PubMed

    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. PMID:26974794

  4. 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.

  5. Neutron total cross section and resonance parameters of /sup 231/Pa

    SciTech Connect

    Hussein, A.R.Z.; Harvey, J.A.; Hill, N.W.; Patterson, J.R.

    1981-08-01

    Time-of-flight measurements of the neutron total cross section of /sup 231/Pa were carried out, in the energy range 0.01 to 10,000 eV, on two sample thicknesses using the Oak Ridge Electron Linear Accelerator as the pulsed neutron source. The multilevel R matrix code MULTI, which includes instrumental resolution and the Doppler broadening, has been used to fit the data. The resonance parameters obtained from the present multilevel R matrix analysis of /sup 231/Pa transmission data from 0.03 to 120 eV are given. 14 refs.

  6. Dynamic dipole polarizability of Li{sup +} embedded in plasmas

    SciTech Connect

    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.

  7. A magnetic resonance imaging study on the articulatory and acoustic speech parameters of Malay vowels

    PubMed Central

    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

  8. Best parameters selection for wavelet packet-based compression of magnetic resonance images.

    PubMed

    Abu-Rezq, A N; Tolba, A S; Khuwaja, G A; Foda, S G

    1999-10-01

    Transmission of compressed medical images is becoming a vital tool in telemedicine. Thus new methods are needed for efficient image compression. This study discovers the best design parameters for a data compression scheme applied to digital magnetic resonance (MR) images. The proposed technique aims at reducing the transmission cost while preserving the diagnostic information. By selecting the wavelet packet's filters, decomposition level, and subbands that are better adapted to the frequency characteristics of the image, one may achieve better image representation in the sense of lower entropy or minimal distortion. Experimental results show that the selection of the best parameters has a dramatic effect on the data compression rate of MR images. In all cases, decomposition at three or four levels with the Coiflet 5 wavelet (Coif 5) results in better compression performance than the other wavelets. Image resolution is found to have a remarkable effect on the compression rate. PMID:10529302

  9. FRETView: a computer program to simplify the process of obtaining fluorescence resonance energy transfer parameters.

    PubMed

    Stevens, Nathan; Dyer, Joanne; Martí, Angel A; Solomon, Marissa; Turro, Nicholas J

    2007-08-01

    The process of modeling the fluorescence resonance energy transfer (FRET) process for a donor-acceptor pair can be rather challenging, yet few computer programs exist that allow such modeling to be done with relative ease. In order to address this, we have developed a Java-based program, FRETView, which allows numerous FRET parameters to be obtained with just a few mouse clicks. Being a Java-based program, it runs equally well on all the major operating systems such as Windows, Mac OS X, Linux, Solaris. The program allows the user to effortlessly input pertinent information about the donor-acceptor pair, including the absorption and/or emission spectra, and outputs the calculated FRET parameters in table format, as well as graphical plots. PMID:17668122

  10. Rough parameter dependence in climate models and the role of Ruelle-Pollicott resonances

    PubMed Central

    Chekroun, Mickaël David; Neelin, J. David; Kondrashov, Dmitri; McWilliams, James C.; Ghil, Michael

    2014-01-01

    Despite the importance of uncertainties encountered in climate model simulations, the fundamental mechanisms at the origin of sensitive behavior of long-term model statistics remain unclear. Variability of turbulent flows in the atmosphere and oceans exhibits recurrent large-scale patterns. These patterns, while evolving irregularly in time, manifest characteristic frequencies across a large range of time scales, from intraseasonal through interdecadal. Based on modern spectral theory of chaotic and dissipative dynamical systems, the associated low-frequency variability may be formulated in terms of Ruelle-Pollicott (RP) resonances. RP resonances encode information on the nonlinear dynamics of the system, and an approach for estimating them—as filtered through an observable of the system—is proposed. This approach relies on an appropriate Markov representation of the dynamics associated with a given observable. It is shown that, within this representation, the spectral gap—defined as the distance between the subdominant RP resonance and the unit circle—plays a major role in the roughness of parameter dependences. The model statistics are the most sensitive for the smallest spectral gaps; such small gaps turn out to correspond to regimes where the low-frequency variability is more pronounced, whereas autocorrelations decay more slowly. The present approach is applied to analyze the rough parameter dependence encountered in key statistics of an El-Niño–Southern Oscillation model of intermediate complexity. Theoretical arguments, however, strongly suggest that such links between model sensitivity and the decay of correlation properties are not limited to this particular model and could hold much more generally. PMID:24443553

  11. Brownian dipole rotator in alternating electric field.

    PubMed

    Rozenbaum, V M; Vovchenko, O Ye; Korochkova, T Ye

    2008-06-01

    The study addresses the azimuthal jumping motion of an adsorbed polar molecule in a periodic n -well potential under the action of an external alternating electric field. Starting from the perturbation theory of the Pauli equation with respect to the weak field intensity, explicit analytical expressions have been derived for the time dependence of the average dipole moment as well as the frequency dependences of polarizability and the average angular velocity, the three quantities exhibiting conspicuous stochastic resonance. As shown, unidirectional rotation can arise only provided simultaneous modulation of the minima and maxima of the potential by an external alternating field. For a symmetric potential of hindered rotation, the average angular velocity, if calculated by the second-order perturbation theory with respect to the field intensity, has a nonzero value only at n=2 , i.e., when two azimuthal wells specify a selected axis in the system. Particular consideration is given to the effect caused by the asymmetry of the two-well potential on the dielectric loss spectrum and other Brownian motion parameters. When the asymmetric potential in a system of dipole rotators arises from the average local fields induced by an orientational phase transition, the characteristics concerned show certain peculiarities which enable detection of the phase transition and determination of its parameters. PMID:18643221

  12. Brownian dipole rotator in alternating electric field

    NASA Astrophysics Data System (ADS)

    Rozenbaum, V. M.; Vovchenko, O. Ye.; Korochkova, T. Ye.

    2008-06-01

    The study addresses the azimuthal jumping motion of an adsorbed polar molecule in a periodic n -well potential under the action of an external alternating electric field. Starting from the perturbation theory of the Pauli equation with respect to the weak field intensity, explicit analytical expressions have been derived for the time dependence of the average dipole moment as well as the frequency dependences of polarizability and the average angular velocity, the three quantities exhibiting conspicuous stochastic resonance. As shown, unidirectional rotation can arise only provided simultaneous modulation of the minima and maxima of the potential by an external alternating field. For a symmetric potential of hindered rotation, the average angular velocity, if calculated by the second-order perturbation theory with respect to the field intensity, has a nonzero value only at n=2 , i.e., when two azimuthal wells specify a selected axis in the system. Particular consideration is given to the effect caused by the asymmetry of the two-well potential on the dielectric loss spectrum and other Brownian motion parameters. When the asymmetric potential in a system of dipole rotators arises from the average local fields induced by an orientational phase transition, the characteristics concerned show certain peculiarities which enable detection of the phase transition and determination of its parameters.

  13. Fast determination of beef quality parameters with time-domain nuclear magnetic resonance spectroscopy and chemometrics.

    PubMed

    Pereira, Fabíola Manhas Verbi; Bertelli Pflanzer, Sérgio; Gomig, Thaísa; Lugnani Gomes, Carolina; de Felício, Pedro Eduardo; Colnago, Luiz Alberto

    2013-04-15

    The noteworthy of this study is to predict seven quality parameters for beef samples using time-domain nuclear magnetic resonance (TD-NMR) relaxometry data and multivariate models. Samples from 61 Bonsmara heifers were separated into five groups based on genetic (breeding composition) and feed system (grain and grass feed). Seven sample parameters were analyzed by reference methods; among them, three sensorial parameters, flavor, juiciness and tenderness and four physicochemical parameters, cooking loss, fat and moisture content and instrumental tenderness using Warner Bratzler shear force (WBSF). The raw beef samples of the same animals were analyzed by TD-NMR relaxometry using Carr-Purcell-Meiboom-Gill (CPMG) and Continuous Wave-Free Precession (CWFP) sequences. Regression models computed by partial least squares (PLS) chemometric technique using CPMG and CWFP data and the results of the classical analysis were constructed. The results allowed for the prediction of aforementioned seven properties. The predictive ability of the method was evaluated using the root mean square error (RMSE) for the calibration (RMSEC) and validation (RMSEP) data sets. The reference and predicted values showed no significant differences at a 95% confidence level. PMID:23601874

  14. Multi-parameter sensing with a single magnetoelastic sensor by applying loads on the null locations of multiple resonant modes

    NASA Astrophysics Data System (ADS)

    DeRouin, Andrew; Ghee Ong, Keat

    2016-03-01

    Magnetoelastic sensors are mass sensitive sensors commonly used for stress and pressure measurement, as well as chemical and biological monitoring when combined with a functionalized coating. Magnetoelastic sensors are typically made of free-standing, rectangular strips of magnetoelastic materials that exhibit longitudinal, extensional vibrations due to the excitation of magnetic fields. A single magnetoelastic sensor is generally used to monitor one parameter since only the fundamental resonant frequency is measured. Multiple-parameter sensing in close proximity has previously been achieved by using multiple magnetoelastic sensors of different dimensions and tracking their resonant frequencies independently. However, this requires a large surface area and inconvenient layout of dissimilarly shaped sensors. This paper presents a technique for monitoring multiple parameters with a single magnetoelastic sensor by applying separate mass loads at the null points (points of zero vibration) of multiple resonant modes. Applying a load at a null location does not affect the corresponding resonant mode but alters the resonant frequencies of other modes. Therefore, by isolating the variables of interest to multiple null points and simultaneously measuring the resonant frequency shifts of related resonant modes, the masses at each null location can be calculated. Results showed that changing the coverage at a null location along the width of the sensor can be used to minimize the loading effect on the corresponding resonant mode. In contrast, changing the lengthwise coverage can maximize the loading effect on other resonant modes, thus increasing the mass sensitivity of the sensor. Furthermore, simultaneously applying loads to null points of multiple resonant modes had a nearly additive effect, allowing detection of multiple parameters with a single magnetoelastic sensor.

  15. Study and Optimization of CPT Resonance Parameters in 87 Rb/Ar/Ne Microcells Aimed for Application in Metrology

    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.

  16. Estimation of water retention parameters from nuclear magnetic resonance relaxation time distributions.

    PubMed

    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

  17. The calculation of electrical parameters of AT-cut quartz crystal resonators with the consideration of material viscosity.

    PubMed

    Wang, Ji; Zhao, Wenhua; Du, Jianke; Hu, Yuantai

    2011-01-01

    Electrical parameters like resistance and quality factor of a quartz crystal resonator cannot be determined through vibration analysis without considering the presence of material dissipation. In this study, we use the first-order Mindlin plate equations of piezoelectric plates for thickness-shear vibrations of a simple resonator model with partial electrodes. We derive the expressions of electrical parameters with emphasis on the resistance that is related to the imaginary part of complex elastic constants, or the viscosity, of quartz crystal. Since all electrical parameters are frequency dependent, this procedure provides the chance to study the frequency behavior of crystal resonators with a direct formulation. We understand that the electrical parameters are strongly affected by the manufacturing process, with the plating techniques in particular, but the theoretical approach we presented here will be the first step for the precise estimation of such parameters and their further applications in the analysis of nonlinear behavior of resonators. We calculated the parameters from our simple resonator model of AT-cut quartz crystal with the first-order Mindlin plate theory to demonstrate the procedure and show that the numerical results are consistent with earlier measurements. PMID:20594568

  18. The Dependence Of Nuclear Magnetic Resonance (NMR) Image Contrast On Intrinsic And Operator-Selectable Parameters

    NASA Astrophysics Data System (ADS)

    Wehrli, F. W.; MacFall, J. R.; Glover, G. H.

    1983-12-01

    In nuclear magnetic resonance (NMR) the image pixel value is governed by four intrinsic parameters: the spin density ρ, the spin-lattice relaxation time T1, the spin-spin relaxation time T2 and, for non-stationary spins, the flow velocity v. The extent to which the signal is weighted toward one or several parameters is related to the history of the spin system preceding the detection pulse. In the present work T1 and T2 were determined in vivo for several regions in the CNS from inversion-recovery (T1) And multiple-echo (T2) images, using least-squares fitting procedures. From averaged values of T1 and T2 in grey matter, white matter and CSF, the signal intensity was calculated on the basis of the Bloch equations and plotted as a function of the intrinsic parameters for the three most common imaging pulse sequences. These data are in excellent agreement with images, recorded from normal volunteers on an experimental whole-body imaging system operating at 12.8 MHz (0.3T). The graphical presentation of contrast further will provide the radiologist with a straightforward tool for image interpretation.

  19. Thermal conductivity and resonant multipole interactions.

    NASA Technical Reports Server (NTRS)

    Nyeland, C.; Mason, E. A.; Monchick, L.

    1972-01-01

    Investigation of the influence of resonant multipole interactions on exchanges of rotational energy in molecular collisions, by means of a simple two-state impact-parameter approximation. It is found that dipole-quadrupole and quadrupole-quadrupole interactions can have a significant effect for molecules with low moments of inertia.

  20. Resonance parameters of the first 1/2+ state in Be9 and astrophysical implications

    NASA Astrophysics Data System (ADS)

    Burda, O.; von Neumann-Cosel, P.; Richter, A.; Forssén, C.; Brown, B. A.

    2010-07-01

    Spectra of the Be9(e,e') reaction have been measured at the Superconducting Darmstadt Electron Linear Accelerator at an electron energy of E0=73 MeV and scattering angles of 93° and 141° with high-energy resolution up to excitation energies of Ex=8 MeV. The astrophysically relevant resonance parameters of the first excited 1/2+ state of Be9 have been extracted in a one-level approximation of R-matrix theory, resulting in resonance energy ER=1.748(6) MeV and width ΓR=274(8) keV, which are in good agreement with the latest Be9(γ,n) experiment but with considerably improved uncertainties. However, the reduced B(E1) transition strength deduced from an extrapolation of the (e,e') data to the photon point is smaller by a factor of two. Implications of the new results for possible production of C12 in neutron-rich astrophysical scenarios are discussed.

  1. Neutron total cross-sections and resonance parameters of Mo and Ta

    NASA Astrophysics Data System (ADS)

    Moinul Haque Meaze, A. K. M.; Devan, K.; Lee, Y. S.; Oh, Y. D.; Kim, G. N.; Son, D.

    2007-02-01

    Experimental results of transmissions for the samples of natural molybdenum with thickness 0.0192 atoms/barn and for the four samples of natural tantalum with thickness 0.0222, 0.0111, 0.0055 and 0.0025 atoms/barn are presented in this work. Measurements were carried out at the Pohang Neutron Facility which consists of a 100 MeV Linac, water-cooled tantalum target, and 12 m flight path length. Effective total cross-sections were extracted from the transmission data, and resonance parameters were obtained by using the code SAMMY. The present measurements were compared with other measurements and with the evaluated nuclear data file ENDF/B-VI.8.

  2. Measurement of neutron total cross-section and resonance parameters of xenon

    NASA Astrophysics Data System (ADS)

    Skoy, V. R.; Wang, T. F.; Kim, G. N.; Oh, Y. D.; Cho, M. H.; Ko, I. S.; Namkung, W.

    2009-07-01

    We measured the neutron total cross-sections of natural xenon in the neutron energy region from 0.1 to 40 eV by using the time-of-flight method at the Pohang neutron facility, which consists of an electron linear accelerator, a water-cooled tantalum target with a water moderator, and a 12-m long time-of-flight path. A 6Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm was used as a neutron detector. Notch filters composed of Co, In, Cd were used to estimate the background level and to calculate the neutron flight path length. The present measurement was compared with the existing experimental and the evaluated data. The resonance parameters of Xe isotopes were obtained from the transmission ratio by using the SAMMY code and were compared with other previous results.

  3. Determination of molecular spectroscopic parameters and energy-transfer rates by double-resonance spectroscopy

    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.

  4. R-MATRIX RESONANCE ANALYSIS AND STATISTICAL PROPERTIES OF THE RESONANCE PARAMETERS OF 233U IN THE NEUTRON ENERGY RANGE FROM THERMAL TO 600 eV

    SciTech Connect

    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.

  5. Infrared dipole antenna enhanced by surface phonon polaritons.

    PubMed

    Kim, Hyun Chul; Cheng, Xing

    2010-11-15

    In this Letter, we propose a gold dipole antenna formed on a SiC substrate to achieve a strong concentration of mid-IR radiation based on a synergistic integration of the IR dipole antenna and the resonance excitation of a surface phonon polariton. Numerical simulation based on the finite-difference time-domain technique shows that the intensity enhancement can be greater than 10(7) times at the mid-IR spectral region. The influence of the geometric parameters (i.e., antenna length, gap dimension, antenna thickness, and antenna width) on the antenna field enhancement is also studied. The strong intensity enhancement can find important applications in highly sensitive mid-IR photodetectors and in molecular detection and identification by surface-enhanced IR absorption spectroscopy techniques. PMID:21081984

  6. Addendum to the paper "Dead-time free measurement of dipole-dipole interactions between electron spins" by M. Pannier, S. Veit, A. Godt, G. Jeschke, and H.W. Spiess [J. Magn. Reson. 142 (2000) 331-340

    NASA Astrophysics Data System (ADS)

    Spiess, Hans Wolfgang

    2011-12-01

    The development of four-pulse DEER as described, which has been published in the Journal of Magnetic Resonance more than 10 years ago. The corresponding paper is an example where a slight advance, such as adding a refocusing pulse, which in retrospect looks so simple, can have a remarkable impact on an entire field of science. In our case it offered a simple way to exact measurements of distances between defined species in the nanometer range. The current applications are mainly in determining structures of proteins and nucleic acids.

  7. Controlling magnetic and electric dipole modes in hollow silicon nanocylinders.

    PubMed

    van de Haar, Marie Anne; van de Groep, Jorik; Brenny, Benjamin J M; Polman, Albert

    2016-02-01

    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. PMID:26906780

  8. 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.

  9. Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods

    NASA Astrophysics Data System (ADS)

    Watson, Derek W.; Jenkins, Stewart D.; Ruostekoski, Janne; Fedotov, Vassili A.; Zheludev, Nikolay I.

    2016-03-01

    We show how the elusive toroidal dipole moment appears as a radiative excitation eigenmode in a metamolecule resonator that is formed by pairs of plasmonic nanorods. We analyze one such nanorod configuration—a toroidal metamolecule. We find that the radiative interactions in the toroidal metamolecule can be qualitatively represented by a theoretical model based on an electric point dipole arrangement. Both a finite-size rod model and the point dipole approximation demonstrate how the toroidal dipole moment is subradiant and difficult to excite by incident light. By means of breaking the geometric symmetry of the metamolecule, the toroidal mode can be excited by linearly polarized light and appears as a Fano resonance dip in the forward scattered light. We provide simple optimization protocols for maximizing the toroidal dipole mode excitation. This opens up possibilities for simplified control and driving of metamaterial arrays consisting of toroidal dipole unit-cell resonators.

  10. Achieving high bit rate logical stochastic resonance in a bistable system by adjusting parameters

    NASA Astrophysics Data System (ADS)

    Yang, Ding-Xin; Gu, Feng-Shou; Feng, Guo-Jin; Yang, Yong-Min; Ball, Andrew

    2015-11-01

    The phenomenon of logical stochastic resonance (LSR) in a nonlinear bistable system is demonstrated by numerical simulations and experiments. However, the bit rates of the logical signals are relatively low and not suitable for practical applications. First, we examine the responses of the bistable system with fixed parameters to different bit rate logic input signals, showing that an arbitrary high bit rate LSR in a bistable system cannot be achieved. Then, a normalized transform of the LSR bistable system is introduced through a kind of variable substitution. Based on the transform, it is found that LSR for arbitrary high bit rate logic signals in a bistable system can be achieved by adjusting the parameters of the system, setting bias value and amplifying the amplitudes of logic input signals and noise properly. Finally, the desired OR and AND logic outputs to high bit rate logic inputs in a bistable system are obtained by numerical simulations. The study might provide higher feasibility of LSR in practical engineering applications. Project supported by the National Natural Science Foundation of China (Grant No. 51379526).

  11. Extracting the resonance parameters from experimental data on scattering of charged particles

    NASA Astrophysics Data System (ADS)

    Vaandrager, P.; Rakityansky, S. A.

    2016-02-01

    A new parametrization of the multi-channel S-matrix is used to fit scattering data and then to locate the resonances as its poles. The S-matrix is written in terms of the corresponding “in” and “out” Jost matrices which are expanded in the Taylor series of the collision energy E around an appropriately chosen energy E0. In order to do this, the Jost matrices are written in a semi-analytic form where all the factors (involving the channel momenta and Sommerfeld parameters) responsible for their “bad behavior” (i.e., responsible for the multi-valuedness of the Jost matrices and for branching of the Riemann surface of the energy) are given explicitly. The remaining unknown factors in the Jost matrices are analytic and single-valued functions of the variable E and are defined on a simple energy plane. The expansion is done for these analytic functions and the expansion coefficients are used as the fitting parameters. The method is tested on a two-channel model, using a set of artificially generated data points with typical error bars and a typical random noise in the positions of the points.

  12. Diurnal and seasonal variations in the Schumann resonance parameters observed at Chinese observatories

    NASA Astrophysics Data System (ADS)

    Zhou, Hongjuan; Yu, Haiyan; Cao, Bingxia; Qiao, Xiaolin

    2013-06-01

    The Schumann resonances (SRs) are of great significance for probing the global circuit. The diurnal and seasonal variations in mode amplitudes and frequencies of the first four modes of SR magnetic components based on 2 years measurements at the stations located in China are firstly presented here. The frequencies of all the four modes have their maxima during boreal winter and minima during summer, while the mode amplitudes change oppositely. The variations of both frequencies and amplitudes show their strong relationships with the lighting activity in south-east Asia (0800 UT) which is the nearest source to the observatories in China, while the other sources in Africa (1400 UT) and South America (2000 UT) have less effects on the mode amplitudes of both magnetic components. The effect of day-night asymmetry on SR parameters is estimated by a 3D-FDTD model of the Earth-ionosphere cavity with a single pulse traveling around the equator in a day. Two models of the Earth-ionosphere cavity, namely, a symmetric cavity and a cavity with day-night asymmetric conductivity profile are exploited. It is clear that the minima in the diurnal patterns of the mode frequencies near local sunrise/sunset times are mainly related to the migrations of the global lighting activity, not the day-night ionosphere asymmetry. Moreover, it is concluded that the ionosphere-induced variations of SR parameters including mode frequencies and amplitudes are much smaller than the variations resulting from lighting activity.

  13. Dipole and rotational strengths for overtone transitions of a C2-symmetry HCCH molecular fragment using Van Vleck perturbation theory

    NASA Astrophysics Data System (ADS)

    Abbate, Sergio; Gangemi, Roberto; Longhi, Giovanna

    2002-10-01

    Contact transformation theory up to second order is employed to treat CH-stretching overtone transitions and to calculate dipole and rotational strengths. A general Hamiltonian describing two interacting CH-stretching oscillators is considered, and the Darling-Dennison resonance is appropriately taken into account. The two CH bonds are supposed to be dissymmetrically disposed, so as to represent a chiral HCCH fragment, endowed with C2 symmetry. Analytical expressions of transition moments and dipole and rotational strengths are given in the hypothesis of general electric and magnetic dipole moments with quadratic dependence on coordinates and momenta. Dipole and rotational strengths are then calculated together with frequencies for the fundamental and first three overtone regions in the simplifying hypothesis of the valence optical approach on the coupled-oscillator framework. Simplified analytical expressions thereof in the relevant parameters are presented.

  14. First-principles calculation of parameters of electron paramagnetic resonance spectroscopy in solids.

    PubMed

    Kadantsev, Eugene S; Ziegler, Tom

    2010-12-01

    The hyperfine A-tensor and Zeeman g-tensor parameterize the interaction of an 'effective' electron spin with the magnetic field due to the nuclear spin and the homogeneous external magnetic field, respectively. The A- and g-tensors are the quantities of primary interest in electron paramagnetic resonance (EPR) spectroscopy. In this paper, we review our work [E.S. Kadantsev, T. Ziegler, J. Phys. Chem. A 2008, 112, 4521; E. S. Kadantsev, T. Ziegler, J. Phys. Chem. A 2009, 113, 1327] on the calculation of these EPR parameters under periodic boundary conditions (PBC) from first-principles. Our methodology is based on the Kohn-Sham DFT (KS DFT), explicit usage of Bloch basis set made up of numerical and Slater-type atomic orbitals (NAOs/STOs), and is implemented in the 'full potential' program BAND. Our implementation does not rely on the frozen core approximation. The NAOs/STOs basis is well suited for the accurate representation of the electron density near the nuclei, a prerequisite for the calculation of highly accurate hyperfine parameters. In the case of g-tensor, our implementation is based on the method of Van Lenthe et al. [E. van Lenthe, P. E. S. Wormer, A. van der Avoird, J. Chem. Phys. 1997, 107, 2488] in which the spin-orbital coupling is taken into account variationally. We demonstrate the viability of our scheme by calculating EPR parameters of paramagnetic defects in solids. We consider the A-tensor of 'normal' and 'anomalous' muonium defect in IIIA-VA semiconductors as well as the S2 anion radical in KCl host crystal lattice. PMID:20821407

  15. Theory and experimental verifications of the resonator Q and equivalent electrical parameters due to viscoelastic and mounting supports losses.

    PubMed

    Yong, Yook-Kong; Patel, Mihir S; Tanaka, Masako

    2010-08-01

    A novel analytical/numerical method for calculating the resonator Q and its equivalent electrical parameters due to viscoelastic, conductivity, and mounting supports losses is presented. The method presented will be quite useful for designing new resonators and reducing the time and costs of prototyping. There was also a necessity for better and more realistic modeling of the resonators because of miniaturization and the rapid advances in the frequency ranges of telecommunication. We present new 3-D finite elements models of quartz resonators with viscoelasticity, conductivity, and mounting support losses. The losses at the mounting supports were modeled by perfectly matched layers (PMLs). A previously published theory for dissipative anisotropic piezoelectric solids was formulated in a weak form for finite element (FE) applications. PMLs were placed at the base of the mounting supports to simulate the energy losses to a semi-infinite base substrate. FE simulations were carried out for free vibrations and forced vibrations of quartz tuning fork and AT-cut resonators. Results for quartz tuning fork and thickness shear AT-cut resonators were presented and compared with experimental data. Results for the resonator Q and the equivalent electrical parameters were compared with their measured values. Good equivalences were found. Results for both low- and high-Q AT-cut quartz resonators compared well with their experimental values. A method for estimating the Q directly from the frequency spectrum obtained for free vibrations was also presented. An important determinant of the quality factor Q of a quartz resonator is the loss of energy from the electrode area to the base via the mountings. The acoustical characteristics of the plate resonator are changed when the plate is mounted onto a base substrate. The base affects the frequency spectra of the plate resonator. A resonator with a high Q may not have a similarly high Q when mounted on a base. Hence, the base is an

  16. Density functional theory computation of Nuclear Magnetic Resonance parameters in light and heavy nuclei

    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

  17. Solvents level dipole moments.

    PubMed

    Liang, Wenkel; Li, Xiaosong; Dalton, Larry R; Robinson, Bruce H; Eichinger, Bruce E

    2011-11-01

    The dipole moments of highly polar molecules measured in solution are usually smaller than the molecular dipole moments that are calculated with reaction field methods, whereas vacuum values are routinely calculated in good agreement with available vapor phase data. Whether from Onsager's theory (or variations thereof) or from quantum mechanical methods, the calculated molecular dipoles in solution are found to be larger than those measured. The reason, of course, is that experiments measure the net dipole moment of solute together with the polarized (perturbed) solvent "cloud" surrounding it. Here we show that the reaction field charges that are generated in the quantum mechanical self-consistent reaction field (SCRF) method give a good estimate of the net dipole moment of the solute molecule together with the moment arising from the reaction field charges. This net dipole is a better description of experimental data than the vacuum dipole moment and certainly better than the bare dipole moment of the polarized solute molecule. PMID:21923185

  18. Molecular parameters for weakly bound 2g(aa, ab) and {0}_{u}^{-}(ab) states of molecular iodine and dipole moment functions of transitions to these states

    NASA Astrophysics Data System (ADS)

    Baturo, V. V.; Cherepanov, I. N.; Lukashov, S. S.; Poretsky, S. A.; Pravilov, A. M.

    2016-06-01

    Weakly bound valence states of 2g symmetry, correlating with the I(2 P 3/2) + I(2 P 3/2) (aa) and I(2 P 3/2) + I(2 P 1/2) (ab) dissociation limits, as well as {0}u-(ab) state, were studied using vibrationally resolved luminescence spectra corresponding to transitions from δ2u(3 P 2) and g {0}g-(3 P 1) ion-pair states, in molecular iodine, respectively, populated using a three-step three-color laser excitation scheme. Spectroscopic constants and potential energy curves of the valence states are determined for the first time. Dipole moment functions of δ2u → 2g(aa, ab) and g {0}g- → {0}u-(ab) transitions are found to exponentially decrease.

  19. Wideband microstrip dipole

    NASA Astrophysics Data System (ADS)

    Dey, Supriyo; Aanandan, C. K.; Jose, K. A.; Mohanan, P.; Nair, K. G.

    1992-12-01

    A new wideband half-wave microstrip dipole antenna is described which operates in low-frequency range with more than 5 percent 2:1 VSWR bandwidth. The design is based on a stripline feeding mechanism to prevent radiation from the feeding structure and on proper end-loading of dipole arms to enhance the impedance bandwidth. It is concluded that this dipole can replace the conventional dipoles or existing microstrip antennas in phased array application.

  20. Treatment time reduction through parameter optimization in magnetic resonance guided high intensity focused ultrasound treatments

    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

  1. Estimation of water retention parameters from nuclear magnetic resonance relaxation time distributions

    NASA Astrophysics Data System (ADS)

    Costabel, Stephan; Yaramanci, Ugur

    2013-04-01

    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.

  2. 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.

  3. Measurement of resonance parameters of orbitally excited narrow B0 mesons.

    PubMed

    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; 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; 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; 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

    2009-03-13

    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. PMID:19392106

  4. Measurement of Resonance Parameters of Orbitally Excited Narrow B^0 Mesons

    SciTech Connect

    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.

  5. Methodological aspects in the calculation of parity-violating effects in nuclear magnetic resonance parameters.

    PubMed

    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. PMID:17328593

  6. Spin-torque ferromagnetic resonance (ST-FMR) spectroscopy of localized spin wave modes engineered by applied dipole-field localization

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Pu, Yong; Manuilov, Sergei A.; Pelekhov, Denis V.; Hammel, P. Chris

    Maintaining efficient spin-Hall anti-damping torque in micron-scale devices is challenging near the critical current for auto-oscillation, likely due to spin wave mode degeneracies and nonlinear magnon scattering between them. Localized spin wave modes confined by the strongly inhomogeneous dipole magnetic field of a nearby micro-spherical magnet provides a potentially powerful tool to study these multi-mode interactions by allowing systematic tunability while avoiding potential spurious effects arising from imperfections in fabricating microscopic structures. We demonstrate electrical ST-FMR detection of well-resolved localized modes in a Py/Pt stripe. We find that magnon spectral engineering by means of a micromagnetic particle enables clear observation of damping control and significant reduction of linewidth by means of the anti-damping torque arising from an imposed DC current. The observed linewidth variation suggests that localized modes can be controlled as effectively as the uniform mode.

  7. Parameter dependence of stochastic resonance in the FitzHugh-Nagumo neuron model driven by trichotomous noise

    NASA Astrophysics Data System (ADS)

    Zhang, Huiqing; Yang, Tingting; Xu, Yong; Xu, Wei

    2015-05-01

    We investigate the stochastic resonance in a FitzHugh-Nagumo neuron model driven by trichotomous noise and periodic signal, focusing on the dependence of properties of stochastic resonance (SR) on system parameters. The stochastic resonance is shown through several different measures: system response, power spectrum and signal-to-noise ratio. Firstly, it is found that whether the neuron can fire regularly depends on the cooperative effect of the signal frequency and the signal amplitude for the deterministic FHN neuron. When the forcing amplitude alone is insufficient to cause the neuron firing, the neuron can fire with the addition of trichotomous noise. Secondly, we show that power spectrum is maximized for an optimal value of the noise correlation time, which is the signature of SR. Finally, from studying SNR, the specific system parameters are found to optimize the SR phenomenon.

  8. Blade resonance parameter identification based on tip-timing method without the once-per revolution sensor

    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.

  9. Mutual impedance of nonplanar-skew sinusoidal dipoles

    NASA Technical Reports Server (NTRS)

    Richmond, J. H.; Geary, N. H.

    1974-01-01

    The mutual impedance of nonplanar-skew sinusoidal dipoles is presented as a summation of several exponential integrals with complex arguments. Mathematical models are developed to show the near-zone field of the sinusoidal dipole. The mutual impedance of coupled dipoles is expressed as the sum of four monopole-mobopole impedances to simplify the analysis procedure. The subroutines for solving the parameters of the dipoles are discussed.

  10. Spatially Resolved Observation of Dipole-Dipole Interaction between Rydberg Atoms

    SciTech Connect

    Ditzhuijzen, C. S. E. van; Noordam, L. D.; Heuvell, H. B. van Linden van den; Koenderink, A. F.; Hernandez, J. V.; Robicheaux, F.

    2008-06-20

    We have observed resonant energy transfer between cold Rydberg atoms in spatially separated cylinders. Resonant dipole-dipole coupling excites the 49s atoms in one cylinder to the 49p state while the 41d atoms in the second cylinder are transferred down to the 42p state. We have measured the production of the 49p state as a function of separation of the cylinders (0-80 {mu}m) and the interaction time (0-25 {mu}s). In addition, we measured the width of the electric field resonances. A full many-body quantum calculation reproduces the main features of the experiments.

  11. Antenna impedance measurements in a magnetized plasma. II. Dipole antenna

    SciTech Connect

    Blackwell, David D.; Walker, David N.; Messer, Sarah J.; Amatucci, William E.

    2007-09-15

    This paper presents experimental impedance measurements of a dipole antenna immersed in a magnetized plasma. The impedance was derived from the magnitude and phase of the reflected power using a network analyzer over a frequency range of 1 MHz-1 GHz. The plasma density was varied between 10{sup 7} and 10{sup 10} cm{sup -3} in weakly ({omega}{sub ce}<{omega}{sub pe}) and strongly ({omega}{sub ce}>{omega}{sub pe}) magnetized plasmas in the Space Physics Simulation Chamber at the Naval Research Laboratory. Over this range of plasma conditions the wavelength in the plasma varies from the short dipole limit ({lambda}>>L) to the long dipole limit ({lambda}{approx}L). As with previous impedance measurements, there are two resonant frequencies observed as frequencies where the impedance of the antenna is real. Measurements have indicated that in the short dipole limit the majority of the power deposition takes place at the lower resonance frequency which lies between the cyclotron frequency and the upper hybrid frequency. These measured curves agree very well with the analytic theory for a short dipole in a magnetoplasma. In the long dipole regime, in addition to the short dipole effects still being present, there is resonant energy deposition which peaks at much higher frequencies and correlates to 1/2 and 3/2 wavelength dipole resonances. The wavelengths in the plasma predicted by these resonances are consistent with the antenna radiating R and L-waves.

  12. Triangular Ring Resonator: Direct Measurement of the Parity-Odd Parameters of the Photon Sector of SME

    NASA Astrophysics Data System (ADS)

    Exirifard, Qasem

    2014-03-01

    We introduce the Triangular Ring (TR) resonator. We show that the difference between the clockwise and anti-clockwise resonant frequencies of a vacuum TR resonator is sensitive to the birefringence parity-odd parameters of the photon's sector of the minimal Standard Model Extension (mSME): the Standard Model plus all the perturbative parameters encoding the break of the Lorentz symmetry. We report that utilizing the current technology allows for direct measurement of these parameters with a sensitivity of the parity-even ones and improves the best current resonator bounds by couple of orders of magnitudes. We note that, designing an optical table that rotates perpendicular to the gravitational equipotential surface (geoid) allows for direct measurement of the constancy of the light speed at the vicinity of the earth in all directions, in particular, perpendicular to the geoid. If this table could achieve the precision of the ordinary tables, then it would improve the GPS bounds on the constancy of the light speed perpendicular to geoid by about eight orders of magnitude.

  13. Analytical modeling of Schumann resonance and ELF propagation parameters on Mars with a multi-layered ground

    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.

  14. Nuclear magnetic resonance parameters of atomic xenon dissolved in Gay-Berne model liquid crystal.

    PubMed

    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

  15. Nuclear magnetic resonance parameters of atomic xenon dissolved in Gay-Berne model liquid crystal

    NASA Astrophysics Data System (ADS)

    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 κ=4.4 , κ'=20.0 , and μ=ν=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 Xe129/131 shielding and Xe131 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

  16. Laser-Induced Magnetic Dipole Spectroscopy.

    PubMed

    Hintze, Christian; Bücker, Dennis; Domingo Köhler, Silvia; Jeschke, Gunnar; Drescher, Malte

    2016-06-16

    Pulse electron paramagnetic resonance measurements of nanometer scale distance distributions have proven highly effective in structural studies. They exploit the magnetic dipole-dipole coupling between spin labels site-specifically attached to macromolecules. The most commonly applied technique is double electron-electron resonance (DEER, also called pulsed electron double resonance (PELDOR)). Here we present the new technique of laser-induced magnetic dipole (LaserIMD) spectroscopy based on optical switching of the dipole-dipole coupling. In a proof of concept experiment on a model peptide, we find, already at a low quantum yield of triplet excitation, the same sensitivity for measuring the distance between a porphyrin and a nitroxide label as in a DEER measurement between two nitroxide labels. On the heme protein cytochrome C, we demonstrate that LaserIMD allows for distance measurements between a heme prosthetic group and a nitroxide label, although the heme triplet state is not directly observable by an electron spin echo. PMID:27163749

  17. Resonance scraping

    SciTech Connect

    Collins, T.

    1986-06-01

    Protons lost in a ring leave at a few preferred locations, determined by some non-linear property of the dipoles. This paper suggests taking control of lost protons by beating the magnets at their own game - by means of a designed resonance used as a beam scraper. It is a study of suitable resonances, including estimates of the required multipole element strengths. The appropriate resonances are two-dimensional. A large number of figures is included.

  18. Distinguishing black-hole spin-orbit resonances by their gravitational wave signatures. II. Full parameter estimation

    NASA Astrophysics Data System (ADS)

    Trifirò, Daniele; O'Shaughnessy, Richard; Gerosa, Davide; Berti, Emanuele; Kesden, Michael; Littenberg, Tyson; Sperhake, Ulrich

    2016-02-01

    Gravitational waves from coalescing binary black holes encode the evolution of their spins prior to merger. In the post-Newtonian regime and on the precession time scale, this evolution has one of three morphologies, with the spins either librating around one of two fixed points ("resonances") or circulating freely. In this paper we perform full parameter estimation on resonant binaries with fixed masses and spin magnitudes, changing three parameters: a conserved "projected effective spin" ξ and resonant family Δ Φ =0 ,π (which uniquely label the source); the inclination θJ N of the binary's total angular momentum with respect to the line of sight (which determines the strength of precessional effects in the waveform); and the signal amplitude. We demonstrate that resonances can be distinguished for a wide range of binaries, except for highly symmetric configurations where precessional effects are suppressed. Motivated by new insight into double-spin evolution, we introduce new variables to characterize precessing black hole binaries which naturally reflects the time scale separation of the system and therefore better encode the dynamical information carried by gravitational waves.

  19. Axion induced oscillating electric dipole moments

    SciTech Connect

    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.

  20. Nonlinear Parameters for a Diagnosis of Micro-Scale Cracks Using a Nonlinear Resonant Ultrasound Spectroscopy (nrus)

    NASA Astrophysics Data System (ADS)

    Cheong, Yong-Moo; Alam, M. K.; Kim, CheolGi

    2010-02-01

    Micro-scale cracks in a material are one of the major factors for the determination of life of a structure as well as for the structural integrity. Micro-scale cracks caused by materials degradation and damage will affect the resonance spectrum of a sample only very slightly and be masked by the resolution of the frequency spectrum when we use a standard linear Resonance Ultrasound Spectroscopy (RUS) analysis. Micro-scale damages, however, can produce a nonlinear elastic behavior. The nonlinearity can be measured by increasing the dynamic strain i.e. excitation amplitude in a Nonlinear Resonant Ultrasound Spectroscopy (NRUS) device. In this paper a feasibility of NRUS for a diagnosis of micro-cracks are investigated for low carbon steel CT specimens. A shift of resonance frequency and normalized amplitude of resonance pattern are chosen to correlate the micro-scale cracks or damage. These two nonlinear parameters can be a potential tool for the detection of micro-cracks or damage of a material.

  1. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    NASA Astrophysics Data System (ADS)

    Cho, Herman

    2016-09-01

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3 / 2 , 5 / 2 , 7 / 2, and 9 / 2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  2. Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

    DOE PAGESBeta

    Cho, Herman

    2016-02-28

    Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

  3. Comment on ``Three-body resonances in {sup 6}He, {sup 6}Li, and {sup 6}Be, and the soft dipole mode problem of neutron halo nuclei``

    SciTech Connect

    Hayes, A.C.; Sterbenz, S.M.

    1995-11-01

    In a recent publication Csoto suggests that the sequential decay of {sup 11}Li through resonances in {sup 10}Li could explain the peak seen at 1.2 MeV of excitation in the {sup 11}B({pi}{sup {minus}},{pi}{sup +}) reaction. We point out that this is in conflict with widely accepted notions of probe and target interactions in the measurement of inclusive excitation functions via nuclear reactions ranging from inelastic scattering and heavy-ion transfer reactions to pion double-charge exchange. We also show that the suggested mechanism leads to incorrect predictions in other nuclei, and so we conclude that the apparent success of the mechanism in explaining the observed energy of excited states in the {sup 11}Li and {sup 6}He systems is accidental.

  4. Simple and Inexpensive Classroom Demonstrations of Nuclear Magnetic Resonance and Magnetic Resonance Imaging.

    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)

  5. Design considerations for a large aperture high field superconducting dipole

    SciTech Connect

    Harfoush, F.; Ankenbrandt, C.; Harrison, M.; Kerby, J.; Koepke, K.; Mantsch, P.; Nicol, T.; Riddiford, A.; Theilacker, J.

    1989-03-01

    The final phase of the Fermilab upgrade proposal calls for a new ring of superconducting magnets to be placed in the existing Main Accelerator tunnel. The goal of this design study is to specify a high field dipole (HFD) that is capable of supporting fixed target operation (ramping, resonant extraction) at a field of 6.6T (1.5 Tev) and colliding beam physics at 8.0T (1.8 Tev). The magnetic field quality at high field is set by the large amplitude orbits associated with resonant extraction. The field quality must therefore be at least as good as the existing Tevatron magnets which fulfill these criteria. The high fields and large aperture of this magnet result in large forces on the coil and collar assemblies. Therefore, the cold mass design must be able to sustain these forces while providing sufficient cooling to the coils during 4.2 K fixed target operation, and a minimum heat load during 1.8 K collider operation. The design work is still in progress but a cosine-theta, cold-iron dipole with a 70mm inner diameter coil has been tentatively adopted. This report presents details on the conductor and cable parameters, coil cross-section, projected manufacturing tolerances, iron yoke design, and cold mass assembly. 4 refs., 5 figs., 1 tab.

  6. 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.

  7. Free induction decay caused by a dipole field.

    PubMed

    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. PMID:25871144

  8. Electric Dipole States and Time Reversal Violation in Nuclei.

    NASA Astrophysics Data System (ADS)

    Auerbach, N.

    2016-06-01

    The nuclear Schiff moment is essential in the mechanism that induces a parity and time reversal violation in the atom. In this presentation we explore theoretically the properties and systematics of the isoscalar dipole in nuclei with the emphasis on the low-energy strength and the inverse energy weighted sum which determines the Schiff moment. We also study the influence of the isovector dipole strength distribution on the Schiff moment. The influence of a large neutron excess in nuclei is examined. The centroid energies of the isoscalar giant resonance (ISGDR) and the overtone of the isovector giant dipole resonance (OIVGDR) are given for a range of nuclei.

  9. Generalized Parameter-Adjusted Stochastic Resonance of Duffing Oscillator and Its Application to Weak-Signal Detection

    PubMed Central

    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

  10. Microwave observations of the dipole-dipole interaction between cold Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Afrousheh, K.; Bohlouli, P. Z.; Vagale, D.; Fedorov, M.; Mugford, A.; Martin, J. D. D.

    2004-05-01

    Neighboring Rydberg atoms may strongly interact through electric dipole-dipole couplings. Thus, temporary excitation to Rydberg states has been proposed for implementing elements of quantum information processing using cold neutral atoms. In this work we excited Rb atoms in a MOT to the 45d_5/2 Rydberg state. A microwave pulse was then used to transfer a variable amount of 45d_5/2 atoms to the 46p_3/2 state. Atoms in the 45d and 46p states strongly interact through an always resonant dipole-dipole interaction. We probe this by introducing a second microwave pulse which drives the 45d_5/2-46d_5/2 two photon transition. The dipole-dipole interaction between 46d and 46p states is relatively weak, so the observed spectra are dominated by the 45d-46p couplings between neighboring atoms. These results are discussed in the context of dipole-blockade, as proposed by Lukin et al., Phys. Rev. Lett., 87, 37901 (2001).