Dipole strength distribution of {sup 50}Ti
Gayer, Udo; Beck, Tobias; Beller, Jacob; Mertes, Laura; Pai, Haridas; Pietralla, Norbert; Ries, Philipp; Romig, Christopher; Werner, Volker; Zweidinger, Markus [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany)
2015-07-01
A first nuclear resonance fluorescence (NRF) experiment with a 68% isotopically enriched {sup 50}Ti target has been performed at the superconducting Darmstadt electron linear accelerator S-DALINAC to investigate particle-bound dipole excitations in this nucleus. The target was irradiated with an unpolarized bremsstrahlung photon beam at endpoint energies of 7.5 MeV and 9.7 MeV. The observed excited states are analyzed with respect to their excitation energies, spin quantum numbers and transition strengths. A complementary NRF experiment with polarized photons will be conducted at the High Intensity gamma-ray Source in Durham, NC, USA to determine the polarity of the dipole transitions. Data will be analyzed with regard to the Pygmy Dipole Resonance, a weakly-collective electric dipole excitation which starts to form in nuclei of this mass region. The measured transition strengths will be compared to microscopic calculations in the quasiparticle-phonon model. The investigation of the magnetic dipole strength distribution will focus on strong spin-flip transitions between the p,f spin-orbit partners expected in the nuclear shell model. First results of the measurements and the evaluation will be presented and discussed.
Kumar, Ashok; Thakkar, Ajit J.
2011-08-01
Dipole oscillator strength distributions (DOSDs) for ozone are constructed from experimental photoabsorption cross-sections combined with constraints provided by the Kuhn-Reiche-Thomas sum rule, the high-energy behavior of the dipole-oscillator-strength density, and molar refractivity data. A lack of photoabsorption data in the intermediate energy region from 24 to 524 eV necessitates the use of a mixture rule in that region. For this purpose, a DOSD for O2 is constructed first. The dipole properties for O2 are essentially the same as those obtained in earlier work even though most of the input data is from more recent experiments. A discrepancy is found between the refractivity data and photoabsorption data in the 10-20.6 eV range for ozone. A reliable ozone DOSD of the sort obtained for many other species remains out of reach. However, it is suggested that the true dipole properties of ozone lie between those predicted by two distributions that we present.
Rusev, G.Y.
2006-07-01
Investigations of the dipole-strength distributions in {sup 92}Mo, {sup 98}Mo and {sup 100}Mo were carried out by means of the method of nuclear resonance fluorescence. The low-lying excitations in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been studied in photon-scattering experiments at an electron energy of 6 MeV at the ELBE accelerator and at electron energies from 3.2 to 3.8 MeV at the Dynamitron accelerator. Five levels were observed in {sup 92}Mo. Five levels in {sup 98}Mo and 14 in {sup 100}Mo were identified for the first time in the energy range from 2 to 4 MeV. Dipole-strength distributions up to the neutron-separation energies in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been investigated at the ELBE accelerator. Because of the possible observation of transitions in the neighboring nuclei produced via ({gamma},n) reaction, additional measurements at electron energies of 8.4 and 7.8 MeV, below the neutron-separation energy, were performed on {sup 98}Mo and {sup 100}Mo, respectively. The number of transitions assigned to {sup 92}Mo, {sup 98}Mo and {sup 100}Mo is 340, 485 and 499, respectively, the main part of them being dipole transitions. Statistical properties of the observed transitions are obtained. The continuum contains the ground-state transitions as well as the branching transitions to the low-lying levels and the subsequent deexcitations of these levels. (orig.)
Electric dipole strength distribution below the E1 giant resonance in N = 82 nuclei
Guliyev, Ekber; Kuliev, Ali; Guner, Mehmet
2010-12-01
In this study quasiparticle random-phase approximation with the translational invariant Hamiltonian using deformed mean field potential has been conducted to describe electric dipole excitations in 136Xe, 138Ba, 140Ce, 142Nd, 144Sm and 146Gd isotones. The distribution of the calculated E1 strength shows a resonance like structure at energies between 6-8 MeV exhausting up to 1% of the isovector electric dipole Energy Weighted Sum Rule and in some aspects nicely confirms the experimental data. It has been shown that the main part of E1 strength, observed below the threshold in these nuclei may be interpreted as main fragments of the Pygmy Dipole resonance. The agreement between calculated mean excitation energies as well as summed B(E1) value of the 1- excitations and the available experimental data is quite good. The calculations indicate the presence of a few prominent positive parity 1+ States in heavy N = 82 isotones in the energy interval 6-8 MeV which shows not all dipole excitations were of electric character in this energy range.
Massarczyk, R; Dönau, F; Frauendorf, S; Bemmerer, D; Beyer, R; Butterling, M; Hannaske, R; Junghans, A; Koegler, T; Rusev, G; Schilling, K D; Schramm, G; Tonchev, A P; Tornow, W; Wagner, A
2014-01-01
Dipole strength functions in the chain of xenon isotopes are analyzed on the basis of photon-scatterde experiments with bremsstrahlung at the ELBE facility in Dresden, Germany, and at the HI S facility in Durham, North Carolina, USA. The evolution of dipole strength with neutron excess and nuclear deformation is studied.
Kumar, Ashok; Thakkar, Ajit J.
2010-02-01
The construction of the dipole oscillator strength distribution (DOSD) from theoretical and experimental photoabsorption cross sections combined with constraints provided by the Kuhn-Reiche-Thomas sum rule and molar refractivity data is a well-established technique that has been successfully applied to more than 50 species. Such DOSDs are insufficiently accurate at large photon energies. A novel iterative procedure is developed that rectifies this deficiency by using the high-energy asymptotic behavior of the dipole oscillator strength density as an additional constraint. Pilot applications are made for the neon, argon, krypton, and xenon atoms. The resulting DOSDs improve the agreement of the predicted S2 and S1 sum rules with ab initio calculations while preserving the accuracy of the remainder of the moments. Our DOSDs exploit new and more accurate experimental data. Improved estimates of dipole properties for these four atoms and of dipole-dipole C6 and triple-dipole C9 dispersion coefficients for the interactions among them are reported.
Dinh Dang, N.; Ciemala, M.; Kmiecik, M.; Maj, A.
2013-05-01
The line shapes of giant dipole resonance (GDR) in the decay of the compound nucleus 88Mo, which is formed after the fusion-evaporation reaction 48Ti + 40Ca at various excitation energies E* from 58 to 308 MeV, are generated by averaging the GDR strength functions predicted within the phonon damping model (PDM) using the empirical probabilities for temperature and angular momentum. The average strength functions are compared with the PDM strength functions calculated at the mean temperature and mean angular momentum, which are obtained by averaging the values of temperature and angular momentum using the same temperature and angular momentum probability distributions, respectively. It is seen that these two ways of generating the GDR linear line shape yield very similar results. It is also shown that the GDR width approaches a saturation at angular momentum J≥ 50 ℏ at T=4 MeV and at J≥ 70 ℏ at any T.
Dang, N Dinh; Kmiecik, M; Maj, A
2013-01-01
The line shapes of giant dipole resonance (GDR) in the decay of the compound nucleus $^{88}$Mo, which is formed after the fusion-evaporation reaction $^{48}$Ti + $^{40}$Ca at various excitation energies $E^{*}$ from 58 to 308 MeV, are generated by averaging the GDR strength functions predicted within the phonon damping model (PDM) using the empirical probabilities for temperature and angular momentum. The average strength functions are compared with the PDM strength functions calculated at the mean temperature and mean angular momentum, which are obtained by averaging the values of temperature and angular momentum using the same temperature and angular-momentum probability distributions, respectively. It is seen that these two ways of generating the GDR linear line shape yield very similar results. It is also shown that the GDR width approaches a saturation at angular momentum $J\\geq$ 50$\\hbar$ at $T=$ 4 MeV and at $J\\geq$ 70$\\hbar$ at any $T$.
Schwengner, R; Tsoneva, N; Benouaret, N; Beyer, R; Erhard, M; Grosse, E; Junghans, A R; Klug, J; Kosev, K; Lenske, H; Nair, C; Schilling, K D; Wagner, A
2008-01-01
The dipole response of the N=50 nucleus 90Zr was studied in photon-scattering experiments at the electron linear accelerator ELBE with bremsstrahlung produced at kinetic electron energies of 7.9, 9.0, and 13.2 MeV. We identified 189 levels up to an excitation energy of 12.9 MeV. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. In this way we derived the photoabsorption cross section up to the neutron-separation energy. This cross section matches well the photoabsorption cross section obtained from (gamma,n) data and thus provides information about the extension of the dipole-strength distribution toward energies below the neutron-separation energy. An enhancement of E1 strength has been found in the range of 6 MeV to 11 MeV. Calculations within the framework of the quasiparticle-phonon model ascribe this strength to a vibration of the excessive neutrons against the N = Z neutron-proton c...
"Bi-modal" isoscalar giant dipole strength in Ni-58
Nayak, B. K.; Garg, U.; Hedden, M.; Koss, M.; Li, T.; Liu, Y.; Rao, P. V. Madhusudhana; Zhu, S.; Itoh, M.; Sakaguchi, H.; Takeda, H.; Uchida, M.; Yasuda, Y.; Yosoi, M.; Fujimura, H.; Fujiwara, M.; Hara, K.; Kawabata, T.; Akimune, H.; Harakeh, M. N.
2006-01-01
The strength distribution of the isoscalar giant dipole resonance (ISGDR) in Ni-58 has been obtained over the energy range 10.5-49.5 MeV via extreme forward angle scattering (including 0 degrees) of 386 MeV alpha particles. We observe a "bi-modal" El strength distribution for the first time in an A
Low-lying dipole strengths of {sup 50}Cr
Pai, H.; Beck, T.; Beller, J.; Gayer, U.; Mertes, L.; Pietralla, N.; Ries, P.; Romig, C.; Werner, V.; Zweidinger, M. [Institut fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany)
2015-07-01
Low-lying electric and magnetic dipole strengths (E1 and M1, respectively), particularly Pygmy Dipole Resonance (PDR) and Spin-flip M1 excitations, of atomic nuclei have drawn considerable attention in the last decade. The low-lying dipole strengths of {sup 50}Cr were studied with the method of nuclear resonance fluorescence up to 9.7 MeV, using bremsstrahlung provided by the superconducting Darmstadt electron linear accelerator S-DALINAC. Twenty-four spin-1 states were observed between 3.0 and 9.7 MeV excitation energy, 17 of those for the first time. The excited states' parities are determined through polarized photon scattering at the High Intensity gamma ray Source (HIγS), Triangle Universities Nuclear Laboratory (TUNL) in Durham, NC, USA. Microscopic calculations within the quasiparticle-phonon nuclear model are performed to interpret the dipole strength distribution of {sup 50}Cr. The experimental results of {sup 50}Cr are compared to data on its closed-shell N=28 isotone {sup 52}Cr and may provide information on the onset of the PDR in atomic nuclei.
Linnemann, A; Eberth, J; Enders, J; Fitzler, A; Fransen, C; Guliyev, E; Herzberg, R D; Kuliev, A A; Neumann-Cosel, P V; Pietralla, N; Prade, H; Richter, A; Schwengner, R; Thomas, H G; Weisshaar, D; Wiedenhöver, I
2002-01-01
A nuclear resonance fluorescence experiment with two highly efficient EUROBALL Cluster detectors has been performed on the gamma-soft nucleus sup 1 sup 9 sup 4 Pt. Dipole excitations were observed between 2 MeV and 4 MeV excitation energy. They are tentatively interpreted as the main fragments of the scissors mode based on the measured excitation strengths and a comparison to microscopic calculations in the framework of the quasiparticle random phase approximation (QRPA). The data indicate large differences to the neighbouring isotope sup 1 sup 9 sup 6 Pt: a doubling of the observed dipole strength and a shift of the energy centroid by about 600 keV. None of the currently available models is able to reproduce these features consistently in both nuclei.
Low-energy dipole strength in 112,120Sn
Özel-Tashenov, B; Lenske, H; Krumbholz, A M; Litvinova, E; von Neumann-Cosel, P; Poltoratska, I; Richter, A; Rusev, G; Savran, D; Tsoneva, N
2014-01-01
The 112,120Sn(gamma,gamma') reactions below the neutron separation energies have been studied at the superconducting Darmstadt electron linear accelerator S-DALINAC for different endpoint energies of the incident bremsstrahlung spectrum. Dipole strength distributions are extracted for 112Sn up to 9.5 MeV and for 120Sn up to 9.1 MeV. A concentration of dipole excitations is observed between 5 and 8 MeV in both nuclei. Missing strength due to unobserved decays to excited states is estimated in a statistical model. A fluctuation analysis is applied to the photon scattering spectra to extract the amount of the unresolved strength hidden in background due to fragmentation. The strength distributions are discussed within different model approaches such as the quasiparticle-phonon model and the relativistic time blocking approximation allowing for an inclusion of complex configurations beyond the initial particle-hole states. While a satisfactory description of the fragmentation can be achieved for sufficently large...
Pygmy dipole strength close to particle-separation energies - the case of the Mo isotopes
Rusev, G; Erhard, M; Junghans, A; Kosev, K; Schilling, K D; Schwengner, R; Wagner, A; Rusev, Gencho; Grosse, Eckart; Erhard, Martin; Junghans, Arnd; Kosev, Krasimir; Schilling, Klaus-Dieter; Schwengner, Ronald; Wagner, Andreas
2005-01-01
The distribution of electromagnetic dipole strength in 92, 98, 100 Mo has been investigated by photon scattering using bremsstrahlung from the new ELBE facility. The experimental data for well separated nuclear resonances indicate a transition from a regular to a chaotic behaviour above 4 MeV of excitation energy. As the strength distributions follow a Porter-Thomas distribution much of the dipole strength is found in weak and in unresolved resonances appearing as fluctuating cross section. An analysis of this quasi-continuum - here applied to nuclear resonance fluorescence in a novel way - delivers dipole strength functions, which are combining smoothly to those obtained from (g,n)-data. Enhancements at 6.5 MeV and at ~9 MeV are linked to the pygmy dipole resonances postulated to occur in heavy nuclei.
Excitation energy and strength of the pygmy dipole resonance in stable tin isotopes
Özel, B; Lenske, H; Von Neumann-Cosel, P; Poltoratska, I; Ponomarev, V Yu; Richter, A; Savran, D; Tsoneva, N
2009-01-01
The $^{112,120}$Sn$(\\gamma,\\gamma')$ reactions have been studied at the S-DALINAC. Electric dipole (E1) strength distributions have been determined including contributions from unresolved strength extracted by a fluctuation analysis. Together with available data on $^{116,124}$Sn, an experimental systematics of the pygmy dipole resonance (PDR) in stable even-mass tin isotopes is established. The PDR centroid excitation energies and summed strengths are in reasonable agreement with quasiparticle-phonon model calculations based on a nonrelativistic description of the mean field but disagree with relativistic quasiparticle random-phase approximation predictions.
Low-lying dipole strength in the N = 28 shell-closure nucleus {sup 52}Cr
Pai, Haridas; Beller, Jacob; Benouaret, Nadia; Enders, Joachim; Hartmann, Timo; Karg, Oliver; Neumann-Cosel, Peter von; Pietralla, Norbert; Ponomarev, Vladimir Yu.; Romig, Christopher; Schnorrenberger, Linda; Volz, Stephan; Zweidinger, Markus [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany); Scheck, Marcus [Institut fuer Kernphysik, Technische Universitaet Darmstadt (Germany); School of Engineering, University of the West of Scotland, Paisley (United Kingdom); SUPA, Scottish Universities Physics Alliance, Glasgow (United Kingdom)
2014-07-01
Low-lying electric and magnetic dipole strengths (E1 and M1, respectively) of atomic nuclei have drawn considerable attention in the last decade. The low-lying dipole strength of the N = 28 closed-shell nucleus {sup 52}Cr was studied with nuclear resonance fluorescence up to 9.9 MeV, using bremsstrahlung at the superconducting Darmstadt electron linear accelerator S-DALINAC. Twenty-eight spin-1 states were observed between 5.0 and 9.5 MeV excitation energy, 14 of those for the first time and uncertainties for cross sections were reduced in many cases. Both, electric dipole excitations (E1, around 8 MeV) and magnetic dipole excitations (M1, around 9 MeV) were detected. Microscopic calculations within the quasiparticle-phonon nuclear model were performed using a basis which includes one-, two-, and three-phonon configurations to interpret the dipole strength distributions of {sup 52}Cr and show good agreement with experimental results.
Fragmentation of spin-dipole strength in {sup 90}Zr and {sup 208}Pb
Marketin, T., E-mail: marketin@phy.hr [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany); Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Litvinova, E. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany); Vretenar, D. [Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Ring, P. [Physik-Department der Technischen Universitaet Muenchen, D-85748 Garching (Germany)
2012-01-05
An extension of time-dependent covariant density functional theory that includes particle-vibration coupling is applied to the charge-exchange channel. Spin-dipole excitation spectra are calculated an compared to available data for {sup 90}Zr and {sup 208}Pb. A significant fragmentation is found for all three angular-momentum components of the spin-dipole strength as a result of particle-vibration coupling, as well as a shift of a portion of the strength to higher energy. A high-energy tail is formed in the strength distribution that linearly decreases with energy. Using a model-independent sum rule, the corresponding neutron skin thickness is estimated and shown to be consistent with values obtained at the mean-field level.
Massarczyk, Ralph Jens
2011-01-17
During the last hundred years several models were developed to describe the configuration of nuclei. These models have to make predictions, which should be comparable with experiments. As a standard type of experiment the nuclear resonance fluorescence was established. A nucleus is excited by irradiation with photons. By emitting one or more photons the nucleus decays back to the ground state. With this method it is possible to measure energy levels and to determine the strength of their excitation. A continuum of unresolved peaks gives additional strength. The existing setup at the linear electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf uses bremsstrahlung, produced as a secondary beam in a thin Niobium foil. During the years 2008/09 experiments on the nuclei of {sup 86}Kr and {sup 136}Ba took place there. In this work they will be analyzed. Photon flux and efficiency determination have been done as well as simulations on detector response and non-nuclear scattered background events. For this purpose the GEANT4 package was used. Finally the resulting cross sections were corrected for branching and feeding.
Investigation of dipole strength up to the neutron separation energy at γELBE
Massarczyk R.
2015-01-01
Full Text Available The bremsstrahlung facility at the ELBE accelerator offers the possibility to investigate dipole strength distributions up to the neutron-separation energies with photon up to 16 MeV in energy. The facility and various results for nuclides measured during recent years are presented. One example is the study of the N = 80 nuclide 136Ba. The other presented example is the study of the chain of xenon isotopes from N = 70 to N = 80 which aimed to investigate the influence of nuclear deformation an neutron excess on the dipole strength in the pygmy region. An overview of the analysis is given. GEANT4 simulations were performed to determine the non-nuclear background that has to be removed from the measured spectra. This opens up the possibility to take into account also the strength of unresolved transitions. Simulations of gamma-ray cascades were carried out that consider the transitions from states in the quasi-continuum and allow us to estimate their branching ratios. As a result, the photoabsorption cross sections obtained from corrected intensities of groundstate transitions are compared with theoretical predictions and results within the chain of isotopes. With the help of the measured dipole distribution it is possible to describe gamma-ray spectra following neutron capture more precisely.
Positivity and unitarity constraints on dipole gluon distributions
Peschanski, Robi
2016-01-01
In the high-energy domain, gluon transverse-momentum dependent distributions in nuclei obey constraints coming from positivity and unitarity of the colorless QCD dipole distributions through Fourier-Bessel transformations. Using mathematical properties of Fourier-positive functions, we investigate the nature of these constraints which apply to dipole model building and formulation
Tests of the discretized-continuum method in three-body dipole strengths
Pinilla, E.C., E-mail: epinilla@ulb.ac.be [Physique Nucleaire Theorique et Physique Mathematique, C.P. 229, Universite Libre de Bruxelles (ULB), B 1050 Brussels (Belgium); Baye, D., E-mail: dbaye@ulb.ac.be [Physique Quantique, C.P. 165/82, Universite Libre de Bruxelles (ULB), B 1050 Brussels (Belgium); Physique Nucleaire Theorique et Physique Mathematique, C.P. 229, Universite Libre de Bruxelles (ULB), B 1050 Brussels (Belgium); Descouvemont, P., E-mail: pdesc@ulb.ac.be [Physique Nucleaire Theorique et Physique Mathematique, C.P. 229, Universite Libre de Bruxelles (ULB), B 1050 Brussels (Belgium); Horiuchi, W., E-mail: whoriuchi@riken.jp [RIKEN Nishina Center, Wako 351-0918 (Japan); Suzuki, Y., E-mail: suzuki@nt.sc.niigata-u.ac.jp [Department of Physics, Niigata University, Niigata 950-2181 (Japan); RIKEN Nishina Center, Wako 351-0918 (Japan)
2011-08-15
We investigate the {sup 6}He dipole distribution in a three-body {alpha}+n+n model. Two approaches are used to describe the three-body 1{sup -} continuum: the discretized-continuum method, where the scattering wave functions are approximated by square-integrable functions, and the R-matrix formalism, where their asymptotic behaviour is taken into account. We show that some ambiguity exists in the pseudostate method, owing to the smoothing technique, necessary to derive continuous distributions. We show evidence for the important role of the halo structure in the E1 dipole strength. We also address the treatment of Pauli forbidden states in the three-body wave functions.
A new estimate of average dipole field strength for the last five million years
Cromwell, G.; Tauxe, L.; Halldorsson, S. A.
2013-12-01
The Earth's ancient magnetic field can be approximated by a geocentric axial dipole (GAD) where the average field intensity is twice as strong at the poles than at the equator. The present day geomagnetic field, and some global paleointensity datasets, support the GAD hypothesis with a virtual axial dipole moment (VADM) of about 80 ZAm2. Significant departures from GAD for 0-5 Ma are found in Antarctica and Iceland where paleointensity experiments on massive flows (Antarctica) (1) and volcanic glasses (Iceland) produce average VADM estimates of 41.4 ZAm2 and 59.5 ZAm2, respectively. These combined intensities are much closer to a lower estimate for long-term dipole field strength, 50 ZAm2 (2), and some other estimates of average VADM based on paleointensities strictly from volcanic glasses. Proposed explanations for the observed non-GAD behavior, from otherwise high-quality paleointensity results, include incomplete temporal sampling, effects from the tangent cylinder, and hemispheric asymmetry. Differences in estimates of average magnetic field strength likely arise from inconsistent selection protocols and experiment methodologies. We address these possible biases and estimate the average dipole field strength for the last five million years by compiling measurement level data of IZZI-modified paleointensity experiments from lava flows around the globe (including new results from Iceland and the HSDP-2 Hawaii drill core). We use the Thellier Gui paleointensity interpreter (3) in order to apply objective criteria to all specimens, ensuring consistency between sites. Specimen level selection criteria are determined from a recent paleointensity investigation of modern Hawaiian lava flows where the expected magnetic field strength was accurately recovered when following certain selection parameters. Our new estimate of average dipole field strength for the last five million years incorporates multiple paleointensity studies on lava flows with diverse global and
Dipole strength in 80Se for s process and nuclear transmutation of 79Se
Makinaga, A.; Massarczyk, R.; Beard, M.; Schwengner, R.; Otsu, H.; Al-Abdullah, T.; Anders, M.; Bemmerer, D.; Hannaske, R.; John, R.; Junghans, A. R.; Müller, S. E.; Röder, M.; Schmidt, K.; Wagner, A.
2016-10-01
The dipole strength distribution of 80Se was studied in a photon-scattering experiment by using bremsstrahlung produced with an electron beam of energy 11.5 MeV at the linear accelerator ELBE. We identified 180 γ transitions up to an energy of 9.6 MeV, and analyzed the strength in the quasicontinuum of the spectrum. Simulations of statistical γ -ray cascades were performed to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. The photoabsorption cross section below the neutron-separation energy derived in this way was combined with the photoabsorption cross section obtained from an earlier (γ ,n ) experiment and used as an input for the calculation of 79Se(n ,γ ) reaction rates on the basis of the statistical reaction model.
The isovector dipole strength in nuclei with extreme neutron excess
Arteaga, Daniel Pena; Ring, Peter
2008-01-01
The E1 strength is systematically analyzed in very neutron-rich Sn nuclei, beyond $^{132}$Sn until $^{166}$Sn, within the Relativistic Quasiparticle Random Phase Approximation. The great neutron excess favors the appearance of a deformed ground state for $^{142-162}$Sn. The evolution of the low-lying strength in deformed nuclei is determined by the interplay of two factors, isospin asymmetry and deformation: while greater neutron excess increases the total low-lying strength, deformation hinders and spreads it. Very neutron rich deformed nuclei may not be as good candidates as stable spherical nuclei like $^{132}$Sn for the experimental study of low-lying E1 strength.
Spin-dipole strength functions of $^4$He with realistic nuclear forces
Horiuchi, W
2013-01-01
Both isoscalar and isovector spin-dipole excitations of $^4$He are studied using realistic nuclear forces in the complex scaling method. The ground state of $^4$He and discretized continuum states with $J^{\\pi}=0^-, 1^-, 2^-$ for A=4 nuclei are described in explicitly correlated Gaussians reinforced with global vectors for angular motion. Two- and three-body decay channels are specifically treated to take into account final state interactions. The observed resonance energies and widths of the negative-parity levels are all in fair agreement with those calculated from both the spin-dipole and electric-dipole strength functions as well as the energy eigenvalues of the complex scaled Hamiltonian. Spin-dipole sum rules, both non energy-weighted and energy-weighted, are discussed in relation to tensor correlations in the ground state of $^4$He.
Photon strength distributions in stable even-even molybdenum isotopes
Wagner, A; Erhard, M; Grosse, E; Junghans, A R; Klug, J; Kosev, K; Nair, C; Nankov, N; Rusev, G; Schilling, K D; Schwengner, R
2007-01-01
Electromagnetic dipole-strength distributions up to the particle separation energies are studied for the stable even-even nuclides $^{92,94,96,98,100}$Mo in photon scattering experiments at the superconducting electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf. The influence of inelastic transitions to low-lying excited states has been corrected by a simulation of $\\gamma$ cascades using a statistical model. After corrections for branching ratios of ground-state transitions, the photon-scattering cross-sections smoothly connect to data obtained from $(\\gamma,n)$-reactions. With the newly determined electromagnetic dipole response of nuclei well below the particle separation energies the parametrisation of the isovector giant-dipole resonance is done with improved precision.
Lestrange, Patrick J.; Egidi, Franco; Li, Xiaosong, E-mail: xsli@uw.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)
2015-12-21
The interaction between a quantum mechanical system and plane wave light is usually modeled within the electric dipole approximation. This assumes that the intensity of the incident field is constant over the length of the system and transition probabilities are described in terms of the electric dipole transition moment. For short wavelength spectroscopies, such as X-ray absorption, the electric dipole approximation often breaks down. Higher order multipoles are then included to describe transition probabilities. The square of the magnetic dipole and electric quadrupole are often included, but this results in an origin-dependent expression for the oscillator strength. The oscillator strength can be made origin-independent if all terms through the same order in the wave vector are retained. We will show the consequences and potential pitfalls of using either of these two expressions. It is shown that the origin-dependent expression may violate the Thomas-Reiche-Kuhn sum rule and the origin-independent expression can result in negative transition probabilities.
Horiuchi, W.; Hatakeyama, S.; Ebata, S.; Suzuki, Y.
2017-08-01
Low-lying electric-dipole (E 1 ) strength of a neutron-rich nucleus contains information on neutron-skin thickness, deformation, and shell evolution. We discuss the possibility of making use of total reaction cross sections on 40Ca, 120Sn, and 208Pb targets to probe the E 1 strength of neutron-rich Ca, Ni, and Sn isotopes. They exhibit large enhancement of the E 1 strength at neutron number N >28 , 50, and 82, respectively, due to a change of the single-particle orbits near the Fermi surface participating in the transitions. The density distributions and the electric-multipole strength functions of those isotopes are calculated by the Hartree-Fock+BCS and the canonical-basis-time-dependent-Hartree-Fock-Bogoliubov methods, respectively, using three kinds of Skyrme-type effective interaction. The nuclear and Coulomb breakup processes are respectively described with the Glauber model and the equivalent photon method in which the effect of finite-charge distribution is taken into account. The three Skyrme interactions give different results for the total reaction cross sections because of different Coulomb breakup contributions. The contribution of the low-lying E 1 strength is amplified when the low-incident energy is chosen. With an appropriate choice of the incident energy and target nucleus, the total reaction cross section can be complementary to the Coulomb excitation for analyzing the low-lying E 1 strength of unstable nuclei.
Origins of dipole resonance strength fragmentation in calcium and titanium isotopes
Skorodumina Iu. A.
2012-12-01
Full Text Available Theoretical description of dipole resonances in 46Ti, 48Ti, 50Ti, 48Ca, 40Ca was performed. The distribution of the “hole” among the states of final nuclei was taken into account using information on pick-up reactions. The obtained results are in reasonable agreement with experimental data.
Nuclear deformation and neutron excess as competing effects for pygmy dipole strength
Massarczyk, R; Dönau, F; Frauendorf, S; Anders, M; Bemmerer, D; Beyer, R; Bhatia, C; Birgersson, E; Butterling, M; Elekes, Z; Ferrari, A; Gooden, M E; Hannaske, R; Junghans, A R; Kempe, M; Kelley, J H; Kögler, T; Matic, A; Menzel, M L; Müller, S; Reinhardt, T P; Röder, M; Rusev, G; Schilling, K D; Schmidt, K; Schramm, G; Tonchev, A P; Tornow, W; Wagner, A
2013-01-01
The electromagnetic dipole strength below the neutron-separation energy has been studied for the xenon isotopes with mass numbers A = 124, 128, 132, and 134 in nuclear resonance fluorescence experiments using the ELBE bremsstrahlung facility at Helmholtz-Zentrum Dresden-Rossendorf and the HIgS facility at Triangle Universities Nuclear Laboratory Durham. The systematic study gained new information about the influence of the neutron excess as well as of nuclear deformation on the strength in the region of the pygmy dipole resonance. The results are compared with those obtained for the chain of molybdenum isotopes and with predictions of a random-phase approximation in a deformed basis. It turned out that the effect of nuclear deformation plays a minor role compared with the one caused by neutron excess. A global parametrization of the strength in terms of neutron and proton numbers allowed us to derive a formula capable of predicting the summed E1 strengths in the pygmy region for a wide mass range of nuclides.
Constraining the electric dipole photon strength function in {sup 130}Te
Isaak, J.; Loeher, B.; Savran, D.; Silva, J. [ExtreMe Matter Institute EMMI and Research Division, Darmstadt (Germany); FIAS, Frankfurt (Germany); Ahmed, M.W.; Kelley, J.H.; Tornow, W.; Weller, H.R. [Department of Physics, Duke University, TUNL (United States); Beller, J.; Pietralla, N.; Romig, C.; Zweidinger, M. [Institut fuer Kernphysik, TU Darmstadt (Germany); Glorius, J.; Sonnabend, K. [Institut fuer Angewandte Physik, Goethe-Universitaet Frankfurt (Germany); Krticka, M. [Faculty of Mathematics and Physics, Charles University, Prague (Czech Republic); Rusev, G. [Chemistry Division, LANL (United States); Scheck, M. [School of Engineering, University of the West of Scotland (United Kingdom); Tonchev, A.P. [Physics Division, LLNL (United States)
2014-07-01
The decay properties of photo-excited states in {sup 130}Te have been investigated by means of Nuclear Resonance Fluorescence experiments at the Darmstadt High Intensity Photon Setup (DHIPS) and the High Intensity γ-ray Source (HIγS). The combination of continuous-energy bremsstrahlung on the one hand and the quasi-monoenergetic and linearly polarized photon beam on the other enables a detailed insight into the photoabsorption cross section and the decay behavior of spin-1 states. Comparing these results to simulations within the statistical model allow for constraining the electric dipole photon strength function (E1-PSF). Results are presented and discussed.
M. Spata, G.A. Krafft
2011-09-01
An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a technique for characterizing the nonlinear fields of the beam transport system. Two air-core dipole magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the electron beam. Fourier decomposition of beam position monitor data was then used to measure the amplitude of these frequencies at different positions along the beamline. For a purely linear transport system one expects to find solely the frequencies that were applied to the dipoles with amplitudes that depend on the phase advance of the lattice. In the presence of nonlinear fields one expects to also find harmonics of the driving frequencies that depend on the order of the nonlinearity. The technique was calibrated using one of the sextupole magnets in a CEBAF beamline and then applied to a dipole to measure the sextupole and octupole strength of the magnet. A comparison is made between the beam-based measurements, results from TOSCA and data from our Magnet Measurement Facility.
Strength Distribution Analysis of Typical Staple Fibers
无
2005-01-01
The strength of staple fiber is an important property for yarns and fabrics. Usually there are variations in individual fiber strength, and this will affect the final strength of yarns and fabrics. In this study, Weibull distribution function is used to analyze the strength distribution of various staplefibers. The strengths of wool, silk, cotton, flax, acrylic, polyester, glass, aramid and carbon fiber are tested. It isfound that the strengths of cotton, polyester, glass, aramid and carbon fiber fit well with the two-factor Weibulldistribution, while those of wool and silk with the threefactir Weibull distribution. However, the strength distributionof flax cannot be expressed by either two- or three-factor Weibull distribution convincingly.
High-resolution dipole (e, e) study for optical oscillator strengths of helium
凤任飞; 杨炳忻; 武淑兰; 邢士林; 张芳; 钟志萍; 郭学哲; 徐克尊
1996-01-01
The optical oscillator strengths of helium have been studied by a high-resolution dipole (e, e) method on the recently built high-resolution fast-electron energy-loss spectrometer. The difficulties of optical measurement have been avoided and the experimental precision has been improved by using this method. The optical oscillator strength density spectrum corresponding to the 1S n’P transitions and ionization of helium has been measured in the energy loss range of 21 - 26 eV. And the same work corresponding to the autoionization resonance region has been done in energy loss ranges of 59-67 eV and 69-74 eV. The above results have also been compared with those of the previous work.
Dodson, Christopher M
2012-01-01
Given growing interest in optical-frequency magnetic dipole transitions, we use intermediate coupling calculations to identify strong magnetic dipole emission lines that are well suited for experimental study. The energy levels for all trivalent lanthanide ions in the 4fn configuration are calculated using a detailed free ion Hamiltonian, including electrostatic and spin-orbit terms as well as two-body, three-body, spin-spin, spin-other-orbit, and electrostatically correlated spin-orbit interactions. These free ion energy levels and eigenstates are then used to calculate the oscillator strengths for all ground-state magnetic dipole absorption lines and the spontaneous emission rates for all magnetic dipole emission lines including transitions between excited states. A large number of strong magnetic dipole transitions are predicted throughout the visible and near-infrared spectrum, including many at longer wavelengths that would be ideal for experimental investigation of magnetic light-matter interactions wit...
Pygmy dipole strength in {sup 86}Kr and systematics of N=50 isotones
Schwengner, R.; Bemmerer, D.; Beyer, R.; Junghans, A.R.; Marta, M.; Schilling, K.D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany); Massarczyk, R.; Hannaske, R. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany); TU Dresden (Germany); Rusev, G.; Kelley, J.H.; Kwan, E.; Raut, R.; Tonchev, A.; Tornow, W. [Triangle Universities Nuclear Laboratory (TUNL), Durham NC (United States); Tsoneva, N.; Lenske, H. [Universitaet Giessen (Germany)
2013-07-01
We present results of the first photon-scattering study of {sup 86}Kr. Experiments were carried out with bremsstrahlung at the ELBE accelerator of HZDR and with monoenergetic, polarized γ rays at the HIγS facility of TUNL. A high-pressure gas target was used. We identified about 40 states with J{sup π} = 1{sup -} up to the neutron-separation energy for the first time. For the determination of the absorption cross section, strength in the quasicontinuum was taken into account and a correction of the cross section for inelastic transitions was performed on the basis of simulations of statistical γ-ray cascades. The resulting absorption cross section shows enhanced strength considered as a pygmy dipole resonance (PDR) and is compared with predictions of the quasiparticle-phonon model. The behavior of PDR strength within the series of N=50 isotones is discussed. Enhanced photon strength may influence neutron-capture reaction rates relevant for transmutation studies.
Pygmy dipole resonance and dipole polarizability in 90Zr
Iwamoto, C.; Tamii, A.; Utsunomiya, H.; Akimune, H.; Nakada, H.; Shima, T.; Hashimoto, T.; Yamagata, T.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Suzuki, T.; Fujita, H.; Shimbara, Y.; Nagashima, M.; Sakuda, M.; Mori, T.; Izumi, T.; Okamoto, A.; Kondo, T.; Lui, T.-W.; Bilgier, B.; Kozer, H. C.; Hatanaka, K.
2014-05-01
Electric dipole (E1) reduced transition probability B(E1) of 90Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability αD which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.
Pygmy dipole resonance and dipole polarizability in {sup 90}Zr
Iwamoto, C.; Tamii, A.; Shima, T.; Hashimoto, T.; Suzuki, T.; Fujita, H.; Hatanaka, K. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Utsunomiya, H.; Akimune, H.; Yamagata, T.; Okamoto, A.; Kondo, T. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan); Nakada, H. [Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage, Chiba 263-8522 (Japan); Kawabata, T. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Fujita, Y. [Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 (Japan); Matsubara, H. [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Shimbara, Y.; Nagashima, M. [Department of Physics, Niigata University, Niigata 950-21-2 (Japan); Sakuda, M.; Mori, T. [Department of Physics, Okayama University, Okayama 900-0082 (Japan); 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.
RELATIONSHIPS BETWEEN AUTUMN INDIAN OCEAN DIPOLE MODE AND THE STRENGTH OF SCS SUMMER MONSOON
LI Dong-hui; ZHANG Gui; ZHU Yi-min; TAN Yan-ke; WANG Xue-zhong
2007-01-01
Based on 1948 - 2004 monthly Reynolds Sea Surface Temperature (SST) and NCEP/NCAR atmospheric reanalysis data, the relationships between autumn Indian Ocean Dipole Mode (IODM) and the strength of South China Sea (SCS) Summer Monsoon are investigated through the EOF and smooth correlation methods. The results are as the following. (1) There are two dominant modes of autumn SSTA over the tropical Indian Ocean. They are the uniformly signed basin-wide mode (USBM) and Indian Ocean dipole mode (IODM), respectively. The SSTA associated with USBM are prevailing decadal to interdecadal variability characterized by a unanimous pattern, while the IODM mainly represents interannual variability of SSTA. (2) When positive (negative) IODM exists over the tropical Indian Ocean during the preceding fall,the SCS summer monsoon will be weak (strong). The negative correlation between the interannual variability of IODM and that of SCS summer monsoon is significant during the warm phase of long-term trend but insignificant during the cool phase. (3) When the SCS summer monsoon is strong (weak), the IODM will be in its positive (negative) phase during the following fall season. The positive correlation between the interannual variability of SCS summer monsoon and that of IODM is significant during both the warm and cool phase of the long-term trend, but insignificant during the transition between the two phases.
Amusia, M Ya; Felfli, Z; Msezane, A Z
2007-01-01
The generalized oscillator strengths (GOS) of discrete excitations np-nd, both dipole (L=1) and octupole (L=3) are studied, the latter for the first time. We demonstrate that although the relevant transitions in the same atom are closely located in energy, the dependence of their GOS on the momentum transfer q squared, is remarkably different, so that the GOS corresponding to L=3 have at least one extra maximum as a function of q squared and dominate over those of the L=1, starting from about q=1.25$ atomic unit (a.u.). The calculations were performed in the one particle Hartree-Fock approximation and with account of many-electron correlations via the Random Phase Approximation with Exchange. The GOS are studied for values of q squared up to 30 a.u.
江莎; 刘子怡; 夹国华; 段昌奎
2009-01-01
Lead borate glasses xB2O3+(99-x)PbO+0.5Eu2O3(x=70,60,...,10) were prepared by melt-quenching method.The luminescent properties were characterized with excitation and emission spectra.The emission intensities for 5D0-7FJ(J=0-4) were analyzed to give variation of the relative electric dipole line strengths with the composition of glasses so as to examine the crucial implicit assumption of independent electric dipole line strength on the composition of glass in the Phys.Rev.Lett.2003,91,203903 paper studying l...
On minimal energy dipole moment distributions in regular polygonal agglomerates
Rosa, Adriano Possebon; Cunha, Francisco Ricardo; Ceniceros, Hector Daniel
2017-01-01
Static, regular polygonal and close-packed clusters of spherical magnetic particles and their energy-minimizing magnetic moments are investigated in a two-dimensional setting. This study focuses on a simple particle system which is solely described by the dipole-dipole interaction energy, both without and in the presence of an in-plane magnetic field. For a regular polygonal structure of n sides with n ≥ 3 , and in the absence of an external field, it is proved rigorously that the magnetic moments given by the roots of unity, i.e. tangential to the polygon, are a minimizer of the dipole-dipole interaction energy. Also, for zero external field, new multiple local minima are discovered for the regular polygonal agglomerates. The number of found local extrema is proportional to [ n / 2 ] and these critical points are characterized by the presence of a pair of magnetic moments with a large deviation from the tangential configuration and whose particles are at least three diameters apart. The changes induced by an in-plane external magnetic field on the minimal energy, tangential configurations are investigated numerically. The two critical fields, which correspond to a crossover with the linear chain minimal energy and with the break-up of the agglomerate, respectively are examined in detail. In particular, the numerical results are compared directly with the asymptotic formulas of Danilov et al. (2012) [23] and a remarkable agreement is found even for moderate to large fields. Finally, three examples of close-packed structures are investigated: a triangle, a centered hexagon, and a 19-particle close packed cluster. The numerical study reveals novel, illuminating characteristics of these compact clusters often seen in ferrofluids. The centered hexagon is energetically favorable to the regular hexagon and the minimal energy for the larger 19-particle cluster is even lower than that of the close packed hexagon. In addition, this larger close packed agglomerate has two
Distribution of crushing strength of tablets
Sonnergaard, Jørn
2002-01-01
as a material constant. However, the estimation of this parameter is laborious and subject to estimation problems. It is shown that the Weibull modulus is inherently connected to the coefficient of variation and that the information obtained from the modulus is unclear. The distribution of crushing strength...... data from nine model tablet formulations and four commercial tablets are shown to follow the normal distribution. The importance of proper cleaning of the crushing strength apparatus is demonstrated. Copyright © 2002 Elsevier Science B.V....
The weakening of the ENSO-Indian Ocean Dipole (IOD) coupling strength in recent decades
Ham, Yoo-Geun; Choi, Jun-Young; Kug, Jong-Seong
2016-09-01
This study examines a recent weakening of the coupling between the El Nino-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) mode after the 2000s and 2010s compared to the previous two decades (1980s and 1990s). The correlation between the IOD during the September-November season and the Nino3.4 index during the December-February season is 0.21 for 1999-2014, while for the previous two decades (1979-1998) it is 0.64. It is found that this weakening of the ENSO-IOD coupling during the 2000s and 2010s is associated with different spatial patterns in ENSO evolution during the boreal spring and summer seasons. During the boreal spring season of the El Nino developing phase, positive precipitation anomalies over the northern off-equatorial western Pacific is systematically weakened during the 2000s and 2010s. This also weakens the low-level cross-equatorial southerly flow, which can cause local negative precipitation anomalies over the maritime continent through increased evaporation and cold and dry moist energy advection. The weakened negative precipitation anomalies over the maritime continent reduces the amplitude of the equatorial easterly over the IO, therefore, suppresses a ENSO-related IOD variability. An analysis using climate models that participated in the Coupled Model Intercomparison Project phase 5 (CMIP5) supports this observational findings that the amplitude of the cross-equatorial southerly flow and associated suppressed convective activities over the maritime continent during the El Nino developing season are critical for determining the ENSO-IOD coupling strength in climate models.
Gamow-Teller and dipole strength in the {sup 208}Pb(n,p) reaction
Raywood, K.J.; Long, S.A.; Spicer, B.M.
1997-06-01
Earlier date on the {sup 208}Pb(n.p){sup 208}Tl reaction at 198 MeV has been analysed using the multipole decomposition technique, and the contributions tot he spectra from L=0 and 1 transitions determined. The L=0 cross section has been found to be smaller than values given by the calculations of Macfarlane for Gamow-Teller transitions, using three different forms for the population of single particle states about the Fermi energy. Comparison is made with GT-strength values obtained from a more recent mean field calculation of these populations, and with an older nuclear structure calculation of properties of the lead nuclei. the L=1 strength distribution is also reported. 13 refs., 4 figs.
Fedorets, I D
2002-01-01
Radiative strength functions for dipole transitions from the compound-nuclei states to excited states of the sup 4 sup 9 V and sup 5 sup 1 V nuclei are determined from the resonance-averaged intensities of primary gamma-rays in the (p, gamma) reaction measured in the proton energy range of 1.5-3.5 MeV. The data so obtained are compared with predictions of various models. The best description for E1 transitions is achieved on the base of the model accounting for the dependence of the strength function on the gamma-ray energy, temperature, and nuclear shell structure
Rijssel, Jos van; Kuipers, Bonny W.M.; Erné, Ben H., E-mail: B.H.Erne@uu.nl
2015-04-15
High-frequency applications of magnetic nanoparticles, such as therapeutic hyperthermia and magnetic particle imaging, are sensitive to nanoparticle size and dipole moment. Usually, it is assumed that magnetic nanoparticles with a log-normal distribution of the physical size also have a log-normal distribution of the magnetic dipole moment. Here, we test this assumption for different types of superparamagnetic iron oxide nanoparticles in the 5–20 nm range, by multimodal fitting of magnetization curves using the MINORIM inversion method. The particles are studied while in dilute colloidal dispersion in a liquid, thereby preventing hysteresis and diminishing the effects of magnetic anisotropy on the interpretation of the magnetization curves. For two different types of well crystallized particles, the magnetic distribution is indeed log-normal, as expected from the physical size distribution. However, two other types of particles, with twinning defects or inhomogeneous oxide phases, are found to have a bimodal magnetic distribution. Our qualitative explanation is that relatively low fields are sufficient to begin aligning the particles in the liquid on the basis of their net dipole moment, whereas higher fields are required to align the smaller domains or less magnetic phases inside the particles. - Highlights: • Multimodal fits of dilute ferrofluids reveal when the particles are multidomain. • No a priori shape of the distribution is assumed by the MINORIM inversion method. • Well crystallized particles have log-normal TEM and magnetic size distributions. • Defective particles can combine a monomodal size and a bimodal dipole moment.
Gervais, M.; Moore, K.; Cowling, S.
2009-05-01
The interaction of moist easterly trade winds and high Central American topography creates tropical rainforests in the mountains of Central America. Understanding changes in precipitation in this region is important because these rain forests host a wealth of biodiversity and are sensitive to changes in precipitation. This study focuses on causes of interannual variability in Central American precipitation. Specifically, we find that the relative phases of the Atlantic Nino and Pacific El Nino Southern Oscillation are related to the strength of the trade winds and precipitation over Central America. These relative phases are quantified through the creation of the Pacific Atlantic Dipole index, which is the difference between the Atlantic Nino and the El Nino Southern Oscillation indices. An index of moisture transport over Central America is also created. We find that the Pacific- Atlantic dipole is positively correlated to both the moisture transport index and to a new Central American precipitation station data set, comprised of 43 stations and spanning the period 1961-2000. Composites of years of high and low Pacific-Atlantic dipole index reveal the spatial pattern associated with its variability. These showed that when the PAD is low (high), there is a strengthening (weakening) of the subtropical high and a decrease (increase) in pressure over the eastern equatorial Pacific. This causes an increase (decrease) in the trade wind strength and subsequently a decrease (increase) in Central American precipitation. We conclude that the PAD index represents a dipole in sea surface temperature and sea level pressure between the Atlantic and Pacific Oceans. In the future, this could be used to predict interannual changes in trade wind strength and precipitation in Central America. With current changes in climate, a further understanding of this relationship may be important for the sensitive ecology in the region.
Transition energy and dipole oscillator strength for 1s22p-1s2nd of Cr21+ ion
Wang Zhi-Wen; Liu Ying; Hu Mu-Hong; Li Xin-Ru; Wang Ya-Nan
2008-01-01
The transition energies, wavelengths and dipole oscillator strengths of 1s22p-1s2nd (3 ≤ n ≤ 9) for Cr21+ ion are calculated. The fine structure splittings of 1s2nd (n ≤ 9) states for this ion are also calculated. In calculating energy, we have estimated the higher-order relativistic contribution under a hydrogenic approximation. The quantum defect of Rydberg series 1s2nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experimental data available in the literature. Combining the quantum defect theory with the discrete oscillator strengths, the discrete oscillator strengths for the transitions from initial state 1s22p to highly excited 1s2nd states (n ≥ 10) and the oscillator strength density corresponding to the bound-free transitions are obtained.
Purcell effect of asymmetric dipole source distributions in nanowire resonators
Filonenko, Konstantin; Duggen, Lars; Adam, Jost;
Metal nanowire resonators allow subwavelength mode confinement and thereby the strong Purcell effect. Recent progress in fabrication of plasmonic nanowire lasers requires reliable approaches in studying resonators, where metal nanowire is an essential constitutive element. A semi-analytic study......, capable of treating finite-length axially-symmetric nanowire configurations, was reported in. In some nanolaser configurations, however, one needs to treat asymmetric source distributions, e.g. the single quantum dot placed at some distance from the nanowire axis. We investigate the Purcell effect...... of the asymmetric source distributions in proximity to the metal nanowire in two configurations: a metal cylinder truncated by the PEC plates and finite metal cylinder in free-space. In order to evaluate Purcell factor the mode eigenvalues are precalculated using Comsol Multiphysics radio frequency module. We...
Purcell effect of asymmetric dipole source distributions in nanowire resonators
Filonenko, Konstantin; Duggen, Lars; Adam, Jost;
2015-01-01
Metal nanowire resonators allow subwavelength mode confinement and thereby the strong Purcell effect. Recent progress in fabrication of plasmonic nanowire lasers requires reliable approaches in studying resonators, where metal nanowire is an essential constitutive element. A semi-analytic study......, capable of treating finite-length axially-symmetric nanowire configurations, was reported in. In some nanolaser configurations, however, one needs to treat asymmetric source distributions, e.g. the single quantum dot placed at some distance from the nanowire axis. We investigate the Purcell effect...... of the asymmetric source distributions in proximity to the metal nanowire in two configurations: a metal cylinder truncated by the PEC plates and finite metal cylinder in free-space. In order to evaluate Purcell factor the mode eigenvalues are precalculated using Comsol Multiphysics radio frequency module. We...
Kumar, Ashok; Thakkar, Ajit J.
2011-11-01
Experimental photoabsorption cross-sections combined with constraints provided by the Kuhn-Reiche-Thomas sum rule and the high-energy behavior of the dipole-oscillator-strength density are used to construct dipole oscillator strength distributions for buckminsterfullerene (C60). The distributions are used to predict dipole sum rules Sk, mean excitation energies Ik, the frequency dependent polarizability, and C6 coefficients for the long-range dipole-dipole interactions of C60 with a variety of atoms and molecules.
Geomagnetic dipole strength and reversal rate over the past two million years.
Valet, Jean-Pierre; Meynadier, Laure; Guyodo, Yohan
2005-06-09
Independent records of relative magnetic palaeointensity from sediment cores in different areas of the world can be stacked together to extract the evolution of the geomagnetic dipole moment and thus provide information regarding the processes governing the geodynamo. So far, this procedure has been limited to the past 800,000 years (800 kyr; ref. 3), which does not include any geomagnetic reversals. Here we present a composite curve that shows the evolution of the dipole moment during the past two million years. This reconstruction is in good agreement with the absolute dipole moments derived from volcanic lavas, which were used for calibration. We show that, at least during this period, the time-averaged field was higher during periods without reversals but the amplitude of the short-term oscillations remained the same. As a consequence, few intervals of very low intensity, and thus fewer instabilities, are expected during periods with a strong average dipole moment, whereas more excursions and reversals are expected during periods of weak field intensity. We also observe that the axial dipole begins to decay 60-80 kyr before reversals, but rebuilds itself in the opposite direction in only a few thousand years.
van Rijssel, Jozef; Kuipers, Bonny W M; Erne, Ben
2015-01-01
High-frequency applications of magnetic nanoparticles, such as therapeutic hyperthermia and magnetic particle imaging, are sensitive to nanoparticle size and dipole moment. Usually, it is assumed that magnetic nanoparticles with a log-normal distribution of the physical size also have a log-normal d
Continuum contributions to dipole oscillator-strength sum rules for hydrogen in finite basis sets
Oddershede, Jens; Ogilvie, John F.; Sauer, Stephan P. A.;
2017-01-01
Calculations of the continuum contributions to dipole oscillator sum rules for hydrogen are performed using both exact and basis-set representations of the stick spectra of the continuum wave function. We show that the same results are obtained for the sum rules in both cases, but that the conver...
ZERODUR strength modeling with Weibull statistical distributions
Hartmann, Peter
2016-07-01
The decisive influence on breakage strength of brittle materials such as the low expansion glass ceramic ZERODUR is the surface condition. For polished or etched surfaces it is essential if micro cracks are present and how deep they are. Ground surfaces have many micro cracks caused by the generation process. Here only the depths of the micro cracks are relevant. In any case presence and depths of micro cracks are statistical by nature. The Weibull distribution is the model used traditionally for the representation of such data sets. It is based on the weakest link ansatz. The use of the two or three parameter Weibull distribution for data representation and reliability prediction depends on the underlying crack generation mechanisms. Before choosing the model for a specific evaluation, some checks should be done. Is there only one mechanism present or is it to be expected that an additional mechanism might contribute deviating results? For ground surfaces the main mechanism is the diamond grains' action on the surface. However, grains breaking from their bonding might be moved by the tool across the surface introducing a slightly deeper crack. It is not to be expected that these scratches follow the same statistical distribution as the grinding process. Hence, their description with the same distribution parameters is not adequate. Before including them a dedicated discussion should be performed. If there is additional information available influencing the selection of the model, for example the existence of a maximum crack depth, this should be taken into account also. Micro cracks introduced by small diamond grains on tools working with limited forces cannot be arbitrarily deep. For data obtained with such surfaces the existence of a threshold breakage stress should be part of the hypothesis. This leads to the use of the three parameter Weibull distribution. A differentiation based on the data set alone without preexisting information is possible but requires a
Wavelength and oscillator strength of dipole transition 1s22p-1s2nd for Mn22+ ion
WANG ZhiWen; WANG YaNan; HU MuHong; LI XinRu; LIU Ying
2008-01-01
The transition energies, wavelengths and dipole oscillator strengths of 1s22p-1s2nd (3≤n≤9) for Mn22+. ion are calculated. The fine structure splittings of 1s2nd (n ≤9) states for this ion are also evaluated. In calculating energy, the higher-order relativistic contribution is estimated under a hydrogenic approximation. The quantum defect of Rydberg series 1s2nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experi-mental data available in literatures.
Wavelength and oscillator strength of dipole transition 1s22p—1s2nd for Mn22+ ion
2008-01-01
The transition energies, wavelengths and dipole oscillator strengths of 1s22p-1s2nd (3≤n≤9) for Mn22+ ion are calculated. The fine structure splittings of 1s2nd (n≤9) states for this ion are also evaluated. In calculating energy, the higher-order relativistic contribution is estimated under a hydrogenic approximation. The quantum defect of Rydberg series 1s2nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experi-mental data available in literatures.
Non-dipole effects in angular distributions of secondary electrons in fast particle-atom scattering
Amusia, M Ya; Liverts, E Z
2010-01-01
We demonstrate that the angular distribution of electrons knocked out from an atom by a fast charge particle is determined not only by dipole but also by quadrupole transitions, the contribution of which can be considerably enhanced as compared to the case of photoionization. To obtain these matrix elements one has to study the angular distribution of electrons emitted by the atom in its collision with a fast charged particle. The distribution has to be measured relative to the momentum q transferred from the projectile to the target atom. The situation is similar, but not identical to the photoionization studies, where the matrix elements of continuous spectrum atomic quadrupole transitions can be determined by measuring the so-called non-dipole angular anisotropy parameters of photoelectrons. However, they are strongly suppressed as compared to the dipole matrix elements by small ratio of atomic size to the photon wavelength. This suppression is controlled in fast electron-atom collisions, where it can be m...
Tie strength distribution in scientific collaboration networks
Ke, Qing; Ahn, Yong-Yeol
2014-09-01
Science is increasingly dominated by teams. Understanding patterns of scientific collaboration and their impacts on the productivity and evolution of disciplines is crucial to understand scientific processes. Electronic bibliography offers a unique opportunity to map and investigate the nature of scientific collaboration. Recent studies have demonstrated a counterintuitive organizational pattern of scientific collaboration networks: densely interconnected local clusters consist of weak ties, whereas strong ties play the role of connecting different clusters. This pattern contrasts itself from many other types of networks where strong ties form communities while weak ties connect different communities. Although there are many models for collaboration networks, no model reproduces this pattern. In this paper, we present an evolution model of collaboration networks, which reproduces many properties of real-world collaboration networks, including the organization of tie strengths, skewed degree and weight distribution, high clustering, and assortative mixing.
Tie Strength Distribution in Scientific Collaboration Networks
Ke, Qing
2014-01-01
Science is increasingly dominated by teams. Understanding patterns of scientific collaboration and their impacts on the productivity and evolution of disciplines is crucial to understand scientific processes. Electronic bibliography offers a unique opportunity to map and investigate the nature of scientific collaboration. Recent work have demonstrated a counter-intuitive organizational pattern of scientific collaboration networks: densely interconnected local clusters consist of weak ties, whereas strong ties play the role of connecting different clusters. This pattern contrasts itself from many other types of networks where strong ties form communities while weak ties connect different communities. Although there are many models for collaboration networks, no model reproduces this pattern. In this paper, we present an evolution model of collaboration networks, which reproduces many properties of real-world collaboration networks, including the organization of tie strengths, skewed degree and weight distribut...
Transition energy and dipole oscillator strength of 1s23d- 1s2nf transitions for Sc18+ ion
WANG Zhi-wen; ZHANG Nan; HU Mu-hong
2006-01-01
The transition energies of the 1s23d-1s2nf (4≤n ≤9) transitions and fine structure splittings of 1sZnf (n≤9)states for Sc18+ ion are calculated with the full-core plus correlation method.The quantum defect of ls2nf series is determined by the single-channel quantum defect theory.The energies of any highly excited states with n≥ 10 for this series can be reliably predicted using the quantum defect as function of energy.Three alternative forms of the dipole oscillator strengths for the 1s23d-1s2nf (n≤9) transitions of SC18+ ion are calculated with the transition energies and wave functions obtained above.Combining the quantum defect theory with the discrete oscillator strengths,the discrete oscillator strengths for 1s23d-1sEnf (n > 9) transitionsand the oscillator strengths densities corresponding to the bound-free transitions are obtained.
The Distribution of Subjective Memory Strength: List Strength and Response Bias
Criss, Amy H.
2009-01-01
Models of recognition memory assume that memory decisions are based partially on the subjective strength of the test item. Models agree that the subjective strength of targets increases with additional time for encoding however the origin of the subjective strength of foils remains disputed. Under the fixed strength assumption the distribution of…
Gongora, T. A.; Escalante, V.
1991-04-01
RESUMEN Se presentan tablas de intensidades de oscilador de dipolares del tipo (2SP+1)Lp ni - (2SP+l)Lp ml' para 0 esquema de acoplamiento LS y el otro se describe en el esquema de acoplamiento LK, jK 6 jj. Nuestros resultados son utiles en Ia interpretaci6n e identificaci6n de lfneas espectrales entre estados con ntimeros cuanticos similares. ABSTRACT Tables are presented for the relative strength of dipole transitions of the type (2SP+l)Lp ni - (2SP+l)Lp ml' for 0 < Sp < 2, 0 < Lp < 2, 1 < 1 <4, and for any n and m, in which one of the states is described with the Ls coupling scheme, and the other is described with the LK, jK, or jj coupling scheme. Our results are useful in the interpretation and identification of spectral lines between states with similar quantum numbers. K words: ATOMIC AND MOLECULAR DATA - PROBABILITES
Quenching of the Giant Dipole Resonance Strength at High Excitation Energy
Santonocito, D. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Blumenfeld, Y. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay (France); Agodi, C. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Alba, R. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Bellia, G. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia dell' Universita di Catania, via S. Sofia 64, I-95123 Catania (Italy); Coniglione, R. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Delaunay, F. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay (France); Del Zoppo, A. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Finocchiaro, P. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Frascaria, N. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay (France); Hongmei, F. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Lima, V. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay (France); Maiolino, C. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Migneco, E. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia dell' Universita di Catania, via S. Sofia 64, I-95123 Catania (Italy); Piattelli, P. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Sapienza, P. [INFN - Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Scarpaci, J.A. [Institut de Physique Nucleaire, IN2P3-CNRS, F-91406 Orsay (France)
2007-05-15
The evolution with excitation energy of the Giant Dipole Resonance features in nuclei of mass A{approx}108-136 is reviewed. We first discuss the results of the experiments performed with MEDEA studying the GDR gamma decay from hot nuclei populated at excitation energies above 300 MeV. The focus of the paper is on the excitation energy region between 160 and 290 MeV. This region has been investigated through the study of the reactions {sup 116}Sn + {sup 12}C at 17 and 23A MeV, and {sup 116}Sn + {sup 24}Mg at 17A MeV. Gamma-rays were detected using MEDEA in coincidence with evaporation residues detected in MACISTE. The analysis of the gamma-ray spectra and their comparison with statistical calculations are presented. The comparison with {gamma}-ray spectra from the reaction {sup 36}Ar + {sup 98}Mo at higher excitation energies shows a coherent scenario where a progressive reduction of {gamma} multiplicity relative to predictions for 100% of the Energy Weighted Sum Rule is observed above 200 MeV excitation energy. Finally, the existence of a link between disappearance of collective motion and the liquid-gas phase transitions is discussed.
Erhard, M; Nair, C; Schwengner, R; Beyer, R; Klug, J; Kosev, K; Wagner, A; Grosse, E
2010-01-01
Two methods based on bremsstrahlung were applied to the stable even Mo isotopes for the experimental determination of the photon strength function covering the high excitation energy range above 4 MeV with its increasing level density. Photon scattering was used up to the neutron separation energies Sn and data up to the maximum of the isovector giant resonance(GDR) were obtained by photo-activation. After a proper correction for multi-step processes the observed quasi-continuous spectra of scattered photons show a remarkably good match to the photon strengths derived from nuclear photo effect data obtained previously by neutron detection and corrected in absolute scale using the new activation results. The combined data form an excellent basis to derive a shape dependence of the E1 strength in the even Mo isotopes with increasing deviation from the N = 50 neutron shell, i.e. with the impact of quadrupole deformation and triaxiality. The wide energy coverage of the data allows for a stringent assessment of th...
Rusydi, Febdian; Shukri, Ganes; Saputro, Adithya G.; Agusta, Mohammad K.; Dipojono, Hermawan K.; Suprijadi, Suprijadi
2017-04-01
We study the Q/B-band dipole strength of zinc tetrabenzoporphyrin (ZnTBP) using density functional theory (DFT) in various solvents. The solvents are modeled using the polarized continuum model (PCM). The dipole strength calculations are approached by a two-level system, where the Q-band is described by the HOMO → LUMO electronic transition and the B-band by the HOMO-1 → LUMO electronic transition. We compare the results with the experimental data of the Q/B-band intensity ratio. We also perform time-dependent DFT coupled with PCM to calculate the Q/B-band oscillator strength ratio of ZnTBP. The results of both methods show a general trend with respect to the experimental Q/B-band intensity ratio in solvents, except for the calculation in the water solvent. Even so, the approximation is a good starting point for studying the UV-vis spectrum based on DFT study alone.
Antila, Hanne S; Salonen, Emppu
2015-04-15
The Thole induced point dipole model is combined with three different point charge fitting methods, Merz-Kollman (MK), charges from electrostatic potentials using a grid (CHELPG), and restrained electrostatic potential (RESP), and two multipole algorithms, distributed multipole analysis (DMA) and Gaussian multipole model (GMM), which can be used to describe the electrostatic potential (ESP) around molecules in molecular mechanics force fields. This is done to study how the different methods perform when intramolecular polarizability contributions are self-consistently removed from the fitting done in the force field parametrization. It is demonstrated that the polarizable versions of the partial charge models provide a good compromise between accuracy and computational efficiency in describing the ESP of small organic molecules undergoing conformational changes. For the point charge models, the inclusion of polarizability reduced the the average root mean square error of ESP over the test set by 4-10%.
Birkhan, Jonny Hubertus
2016-07-01
In this thesis, proton scattering data on the nucleus {sup 48}Ca at very forward angles had been analysed. The data stem from a measurement campaign which was launched at the Research Centre of Nuclear Physics at Osaka, Japan, in the past. One of the two objectives of this analysis was to extract a value for the static electric dipole polarisability from the isovector giant dipole resonance (IVGDR). The second objective was to extract the total electromagnetic M1 strength B(M1) of the spin-flip transition which excites the prominent 1{sup +} state at an excitation energy of E{sub x}=10.22 MeV. The polarisability was calculated from the distribution of photo-absorption cross sections within an energy range from E{sub x}=11 MeV to E{sub x}=26 MeV. The photo-absorption cross sections had been deduced from the distribution of E1 cross sections by the method of virtual photons. For this purpose the experimental cross sections had been deconvoluted by a multipole deconvolution into an E1 part and a background part. Then, the best estimate of the polarisability is given by α{sub D}=(1.36±0.14) fm{sup 3}. If a E3 model was included into the multipole decomposition of the (p,p') data the result increased up to α{sub D}=(1.50±0.09) fm{sup 3}. The deviation between these two results is mainly due to the fact that the multipole decomposition is very sensitive on the background function. Assuming that the the IVGDR of the nuclei {sup 48}Ca and {sup 40}Ca have approximately the same structure, estimates for the polarisability of the nucleus {sup 48}Ca could be drawn from {sup 40}Ca(γ,abs) data. Additionally, data from a {sup 48}Ca(e,e'n) measurement were used to estimate the polarisability of the nucleus {sup 48}Ca. Its polarisability seems to fall within the range of α{sub D}=(1.50±0.09) fm{sup 3} and α{sub D}=(1.69±0.03) fm{sup 3}. Beside this, it could be shown by the {sup 40}Ca data that a significant contribution to the polarisability has to be expected
Birkhan, Jonny Hubertus
2016-07-01
In this thesis, proton scattering data on the nucleus {sup 48}Ca at very forward angles had been analysed. The data stem from a measurement campaign which was launched at the Research Centre of Nuclear Physics at Osaka, Japan, in the past. One of the two objectives of this analysis was to extract a value for the static electric dipole polarisability from the isovector giant dipole resonance (IVGDR). The second objective was to extract the total electromagnetic M1 strength B(M1) of the spin-flip transition which excites the prominent 1{sup +} state at an excitation energy of E{sub x}=10.22 MeV. The polarisability was calculated from the distribution of photo-absorption cross sections within an energy range from E{sub x}=11 MeV to E{sub x}=26 MeV. The photo-absorption cross sections had been deduced from the distribution of E1 cross sections by the method of virtual photons. For this purpose the experimental cross sections had been deconvoluted by a multipole deconvolution into an E1 part and a background part. Then, the best estimate of the polarisability is given by α{sub D}=(1.36±0.14) fm{sup 3}. If a E3 model was included into the multipole decomposition of the (p,p') data the result increased up to α{sub D}=(1.50±0.09) fm{sup 3}. The deviation between these two results is mainly due to the fact that the multipole decomposition is very sensitive on the background function. Assuming that the the IVGDR of the nuclei {sup 48}Ca and {sup 40}Ca have approximately the same structure, estimates for the polarisability of the nucleus {sup 48}Ca could be drawn from {sup 40}Ca(γ,abs) data. Additionally, data from a {sup 48}Ca(e,e'n) measurement were used to estimate the polarisability of the nucleus {sup 48}Ca. Its polarisability seems to fall within the range of α{sub D}=(1.50±0.09) fm{sup 3} and α{sub D}=(1.69±0.03) fm{sup 3}. Beside this, it could be shown by the {sup 40}Ca data that a significant contribution to the polarisability has to be expected
Nord, A.; Schiller, A.; Eckert, T.; Beck, O.; Besserer, J.; von Brentano, P.; Fischer, R.; Herzberg, R.; Jaeger, D.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H.H.; Rittner, M.; Zilges, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, Allmandring 3, D-70569 Stuttgart (Germany)]|[Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Strasse 77, D-50937 Koeln (Germany)
1996-11-01
Nuclear resonance fluorescence experiments were performed on the rare earth nuclei {sup 155}Gd and {sup 159}Tb to study the fragmentation of the {ital M}1 {ital scissors} {ital mode} in {ital odd} deformed nuclei and to establish a kind of systematics. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.1 MeV) and high resolution Ge-{gamma} spectrometers detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. The results are compared to those observed recently for the neighboring odd nuclei {sup 161,163}Dy and {sup 157}Gd. Whereas in the odd Dy isotopes the dipole strength is rather concentrated, both Gd isotopes show a strong fragmentation of the strength into about 25 ({sup 155}Gd) and 90 transitions ({sup 157}Gd) in the energy range 2{endash}4 MeV. The nucleus {sup 159}Tb linking the odd Dy and Gd isotopes exhibits an intermediate strength fragmentation. In general the observed total strength in the odd nuclei is reduced by a factor of 2{endash}3 as compared to their neighboring even-even isotopes. The different fragmentation behavior of the dipole strengths in the odd Dy and Gd isotopes is unexplained up to now. {copyright} {ital 1996 The American Physical Society.}
Nord, A.; Schiller, A.; Eckert, T.; Beck, O.; Besserer, J.; von Brentano, P.; Fischer, R.; Herzberg, R.-D.; Jäger, D.; Kneissl, U.; Margraf, J.; Maser, H.; Pietralla, N.; Pitz, H. H.; Rittner, M.; Zilges, A.
1996-11-01
Nuclear resonance fluorescence experiments were performed on the rare earth nuclei 155Gd and 159Tb to study the fragmentation of the M1 scissors mode in odd deformed nuclei and to establish a kind of systematics. Using the bremsstrahlung photon beam of the Stuttgart Dynamitron (end point energy 4.1 MeV) and high resolution Ge-γ spectrometers detailed information was obtained on excitation energies, decay widths, transition probabilities, and branching ratios. The results are compared to those observed recently for the neighboring odd nuclei 161,163Dy and 157Gd. Whereas in the odd Dy isotopes the dipole strength is rather concentrated, both Gd isotopes show a strong fragmentation of the strength into about 25 (155Gd) and 90 transitions (157Gd) in the energy range 2-4 MeV. The nucleus 159Tb linking the odd Dy and Gd isotopes exhibits an intermediate strength fragmentation. In general the observed total strength in the odd nuclei is reduced by a factor of 2-3 as compared to their neighboring even-even isotopes. The different fragmentation behavior of the dipole strengths in the odd Dy and Gd isotopes is unexplained up to now.
Jiang, Jun, E-mail: phyjiang@yeah.net [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); School of Engineering, Charles Darwin University, Darwin, Northern Territory, 0909 (Australia); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin, Northern Territory, 0909 (Australia); Cheng, Yongjun, E-mail: cyj83mail@gmail.com [School of Engineering, Charles Darwin University, Darwin, Northern Territory, 0909 (Australia); Academy of Fundamental and Interdisciplinary Science, Harbin Institute of Technology, Harbin 150080 (China); Bromley, M.W.J., E-mail: brom@physics.uq.edu.au [School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4075 (Australia)
2015-01-15
Effective oscillator strength distributions are systematically generated and tabulated for the alkali atoms, the alkaline-earth atoms, the alkaline-earth ions, the rare gases and some miscellaneous atoms. These effective distributions are used to compute the dipole, quadrupole and octupole static polarizabilities, and are then applied to the calculation of the dynamic polarizabilities at imaginary frequencies. These polarizabilities can be used to determine the long-range C{sub 6}, C{sub 8} and C{sub 10} atom–atom interactions for the dimers formed from any of these atoms and ions, and we present tables covering all of these combinations.
Cho, Yasuo; Hirose, Ryusuke
2007-11-02
A local atomic electric dipole moment distribution of Si atoms on Si(111)-(7 x 7) surface is clearly resolved by using a new technique called noncontact scanning nonlinear dielectric microscopy. The dc-bias voltage dependence of the atomic dipole moment on the Si(111)-(7 x 7) surface is measured. At the weak applied voltage of -0.5 V, a positive dipole moment is detected on the Si adatom sites, whereas a negative dipole moment is observed at the interstitial sites of inter Si adatoms. Moreover, the quantitative dependence of the surface dipole moment as a function of the applied dc voltage is also revealed at a fixed point above the sample surface. This is the first successful demonstration of direct atomic dipole moment observation achieved in the field of capacitance measurement.
Interleaving distribution of multifractal strength of 16-channel EEG signals
WANG Wei; NING Xinbao; WANG Jun; ZHANG Sheng; CHEN Jie; LI Lejia
2003-01-01
Multifractal characteristics of 16-channel human electroencephalogram (EEG) signals under eye-closed rest are analyzed for the first time. The result shows that the EEGs from the different sites on the scalp have different multifractal characteristics and the multifractal strength value Δα exhibits a kind of interleaving and left-right opposite distribution on scalp. This distribution rule is consistent with the localization of function and the lateralization theory in physiology. SoΔα can become an effective parameter to describe the brain potential character. And such a Δα stable distribution rule on sites of the scalp means a classic cerebral cortex active state.
Pygmy dipole resonance in stable nuclei
P Von Neumann-Cosel
2010-07-01
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 (, ′) experiments. These help to distinguish between microscopic QRPA calculations based on either a relativistic or a non-relativistic mean-field description, predicting significantly different properties of the PDR. The second part presents a novel approach to measure the complete electric dipole strength distribution from excitation energies starting at about 5 MeV across the giant dipole resonance (GDR) with high-resolution inelastic proton scattering under 0° at energies of a few 100 MeV/nucleon. The case of 208Pb is discussed in detail and first result from a recent experiment on 120Sn is presented.
Wendt, Kyle
2016-03-01
How large is the 48Ca nucleus? While the electric charge distribution of this nucleus was accurately measured decades ago, both experimental and ab initio descriptions of the neutron distribution are deficient. We address this question using ab initio calculations of the electric charge, neutron, and weak distributions of 48Ca based on chiral effective field theory. Historically, chiral effective field theory calculations of systems larger than 4 nucleons have been plagued by strong systematic errors which result in theoretical descriptions that are too dense and over bound. We address these errors using a novel approach that permits us to accurately reproduce binding energy and charge radius of 48Ca, and to constrain electroweak observables such as the neutron radius, electric dipole polarizability, and the weak form factor. For a full list of contributors to this work, please see ``Neutron and weak-charge distributions of the 48Ca nucleus,'' Nature Physics (2015) doi:10.1038/nphys3529.
Stress-strength reliability for general bivariate distributions
Alaa H. Abdel-Hamid
2016-10-01
Full Text Available An expression for the stress-strength reliability R=P(X1
Wu Fuqiang; Yao Weixing
2008-01-01
The reasons of the static strength dispersion and the fatigue life dispersion of composite laminates are analyzed in this article.It is concluded that the inner original defects,which derived from the manufacturing process of composite laminates,are the common and major reason of causing the random distributions of the static strength and the fatigue life.And there is a correlative relation between the two distributions.With the study of statistical relationship between the fatigue loading and the fatigue life in the uniform confidence level and the same survival rate S-N curves of material,the relationship between the static strength distribution and the fatigue life distribution through a material S-N curve model has been obtained.And then the model which is used to describe the distributions of fatigue life of composites,based on their distributions of static strength,is set up.This model reasonably reflects the effects of the inner original defects on the static strength dispersion and on the fatigue life dispersion of composite laminates.The experimental data of three kinds of composite laminates are employed to verify this model,and the results show that this model can predict the random distributions of fatigue life for composites under any fatigue loads fairly well.
Pygmy dipole resonance in 208Pb
Poltoratska, I; Tamii, A; Adachi, T; Bertulani, C A; Carter, J; Dozono, M; Fujita, H; Fujita, K; Fujita, Y; Hatanaka, K; Itoh, M; Kawabata, T; Kalmykov, Y; Krumbholz, A M; Litvinova, E; Matsubara, H; Nakanishi, K; Neveling, R; Okamura, H; Ong, H J; Özel-Tashenov, B; Ponomarev, V Yu; Richter, A; Rubio, B; Sakaguchi, H; Sakemi, Y; Sasamoto, Y; Shimbara, Y; Shimizu, Y; Smit, F D; Suzuki, T; Tameshige, Y; Wambach, J; Yosoi, M; Zenihiro, J
2012-01-01
Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208Pb shows that at very forward angles J^pi = 1- states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(E1) transition strength distribution is extracted for excitation energies up to 9 MeV, i.e., in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to the underlying structure of the E1 transitions, which allows for the first time an experimental extraction of the strength and energy centroid of the PDR.
Harrison, James F
2009-07-28
We calculated the dipole moment function for the ground (3)Sigma(-)(m(S) = +1) state of the open shell molecules, NF, NCl, and NBr, and analyzed it in terms of the charge and spin distribution and the induced atomic dipoles using the Hirshfeld partitioning of the electron density. The smallest dipole moment (0.026ea(0)) obtains with NF, in which the atoms have the largest difference in electronegativity, while the dipole moments in NCl and NBr are 0.441ea(0) and 0.506ea(0), respectively. All dipoles have the N(-)X(+) polarity. In the sigma system alpha spin electrons flow from N to the halogen while beta spin electrons flow in the opposite direction and interestingly from both the sigma and the pi systems of the halogen to the sigma system of N. In NF the number of beta spins lost by F is essentially equal to the number of alpha spins gained and the atomic charges are essentially 0. The small dipole in NF is the result of a slight imbalance in the induced atomic dipoles. For NCl and NBr the halogen loses more beta spins than it gains alpha spins resulting in the polarity N(-)X(+). It is interesting that at equilibrium N gained electrons in the pi system while the halogen lost pi electrons relative to the separated atoms. This however is not back donation in the usual sense because the electrons gained by N have alpha spin while those lost by the halogen have beta spin. Detailed examination of the spin flow shows that the excess alpha electrons in the pi system of N come from an intra-atomic transfer from the N sigma system. The induced atomic dipole moments essentially cancel at all internuclear separations and the polarity of the dipole moment accurately reflects the molecular charge distribution.
Strength distribution of gamma-transitions deexciting superdeformed rotational bands
Lopez-Martens, A P; Khoo, T L; Korichi, A; Hannachi, F; Calderin, I J; Lauritsen, T; Ahmad, I; Carpenter, M P; Fischer, S M; Hackman, G; Janssens, R V F; Nisius, D; Reiter, P; Amro, H; Moore, E F
1999-01-01
The strength distribution of the gamma rays in the decay-out from superdeformed (SD) states is investigated by applying the maximum likelihood method, with special emphasis on the influence of the lower threshold given by experimental conditions. Clear graphical solutions are found, and a careful estimation of the dispersion in the values of the number of degrees of freedom and of the average strength of the most likely chi sup 2 distribution is carried out. For the sup 1 sup 9 sup 4 Hg nucleus, 41 primary transitions from the decay-out of SD states are identified above 2600 keV. It is concluded that they represent the strongest 10% of the transitions selected stochastically from a Porter-Thomas distribution. This would support the scenario of a statistical decay of SD states via coupling to a compound state at normal deformation. However, the occurrence of several very strong direct one-step transitions as previously observed in sup 1 sup 9 sup 4 Hg has a very small probability of the order of 10 sup - sup 4...
Strength distribution of γ-transitions deexciting superdeformed rotational bands
Lopez-Martens, A. P.; Døssing, T.; Khoo, T. L.; Korichi, A.; Hannachi, F.; Calderin, I. J.; Lauritsen, T.; Ahmad, I.; Carpenter, M. P.; Fischer, S. M.; Hackman, G.; Janssens, R. V. F.; Nisius, D.; Reiter, P.; Amro, H.; Moore, E. F.
1999-03-01
The strength distribution of the γ rays in the decay-out from superdeformed (SD) states is investigated by applying the maximum likelihood method, with special emphasis on the influence of the lower threshold given by experimental conditions. Clear graphical solutions are found, and a careful estimation of the dispersion in the values of the number of degrees of freedom and of the average strength of the most likely χ2 distribution is carried out. For the 194Hg nucleus, 41 primary transitions from the decay-out of SD states are identified above 2600 keV. It is concluded that they represent the strongest 10% of the transitions selected stochastically from a Porter-Thomas distribution. This would support the scenario of a statistical decay of SD states via coupling to a compound state at normal deformation. However, the occurrence of several very strong direct one-step transitions as previously observed in 194Hg has a very small probability of the order of 10 -4. This may indicate special selection rules governing the decay. However, based on the absence of strong primary transitions from SD states in adjacent nuclei, the situation in 194Hg is viewed as a very lucky incidence.
Strength distribution of {gamma}-transitions deexciting superdeformed rotational bands
Lopez-Martens, A.P.; Doesing, T.; Khoo, T.L.; Korichi, A.; Hannachi, F.; Calderin, I.J.; Lauritsen, T.; Ahmad, I.; Carpenter, M.P.; Fischer, S.M.; Hackman, G.; Janssens, R.V.F.; Nisius, D.; Reiter, P.; Amro, H.; Moore, E.F
1999-03-08
The strength distribution of the {gamma} rays in the decay-out from superdeformed (SD) states is investigated by applying the maximum likelihood method, with special emphasis on the influence of the lower threshold given by experimental conditions. Clear graphical solutions are found, and a careful estimation of the dispersion in the values of the number of degrees of freedom and of the average strength of the most likely {chi}{sup 2} distribution is carried out. For the {sup 194}Hg nucleus, 41 primary transitions from the decay-out of SD states are identified above 2600 keV. It is concluded that they represent the strongest 10% of the transitions selected stochastically from a Porter-Thomas distribution. This would support the scenario of a statistical decay of SD states via coupling to a compound state at normal deformation. However, the occurrence of several very strong direct one-step transitions as previously observed in {sup 194}Hg has a very small probability of the order of 10{sup -4}. This may indicate special selection rules governing the decay. However, based on the absence of strong primary transitions from SD states in adjacent nuclei, the situation in {sup 194}Hg is viewed as a very lucky incidence.
Khitrov, V A
2001-01-01
The new, model-independent method to estimate simultaneously the level densities excited in the (n,gamma) reaction and the radiative strength functions of dipole transitions is developed. The method can be applied for any nucleus and reaction followed by cascade gamma-emission. It is just necessary to measure the intensities of two-step gamma-cascades depopulating one or several high-excited states and determine the quanta ordering in the main portion of the observed cascades. The method provides a sufficiently narrow interval of most probable densities of levels with given J suppi and radiative strength functions of dipole transitions populating them.
Dipole strength in 144Sm studied via (gamma,n), (gamma,p) and (gamma,alpha) reactions
Nair, Chithra; Erhard, Martin; Bemmerer, Daniel; Beyer, Roland; Grosse, Eckart; Kosev, Krasimir; Marta, Michele; Rusev, Gencho; Schilling, Klaus-Dieter; Schwengner, Ronald; Wagner, Andreas
2010-01-01
Photoactivation measurements on 144Sm have been performed with bremsstrahlung endpoint energies from 10.0 to 15.5 MeV at the bremsstrahlung facility of the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf. The measured activation yield for the 144Sm(gamma,n) reaction is compared with the calculated yield using cross sections from previous photoneutron experiments. The activation yields measured for all disintegration channels 144Sm(gamma,n), (gamma,p) and (gamma,alpha) are compared to the yield calculated by using Hauser-Feshbach statistical models. A new parametrization of the photon strength function is presented and the yield simulated by using the modified photon strength parameters are compared to the experimental data.
Ionic strength independence of charge distributions in solvation of biomolecules
Virtanen, J. J. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Sosnick, T. R. [Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States); Computation Institute, University of Chicago, Chicago, Illinois 60637 (United States); Freed, K. F. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Computation Institute, University of Chicago, Chicago, Illinois 60637 (United States)
2014-12-14
Electrostatic forces enormously impact the structure, interactions, and function of biomolecules. We perform all-atom molecular dynamics simulations for 5 proteins and 5 RNAs to determine the dependence on ionic strength of the ion and water charge distributions surrounding the biomolecules, as well as the contributions of ions to the electrostatic free energy of interaction between the biomolecule and the surrounding salt solution (for a total of 40 different biomolecule/solvent combinations). Although water provides the dominant contribution to the charge density distribution and to the electrostatic potential even in 1M NaCl solutions, the contributions of water molecules and of ions to the total electrostatic interaction free energy with the solvated biomolecule are comparable. The electrostatic biomolecule/solvent interaction energies and the total charge distribution exhibit a remarkable insensitivity to salt concentrations over a huge range of salt concentrations (20 mM to 1M NaCl). The electrostatic potentials near the biomolecule's surface obtained from the MD simulations differ markedly, as expected, from the potentials predicted by continuum dielectric models, even though the total electrostatic interaction free energies are within 11% of each other.
Flaw strength distributions and statistical parameters for ceramic fibers: The normal distribution
R'Mili, M.; Godin, N.; Lamon, J.
2012-05-01
The present paper investigates large sets of ceramic fibre failure strengths (500 to 1000 data) produced using tensile tests on tows that contained either 500 or 1000 filaments. The probability density function was determined through acoustic emission monitoring which allowed detection and counting of filament fractures. The statistical distribution of filament strengths was described using the normal distribution. The Weibull equation was then fitted to this normal distribution for estimation of statistical parameters. A perfect agreement between both distributions was obtained, and a quite negligible scatter in statistical parameters was observed, as opposed to the wide variability that is reported in the literature. Thus it was concluded that flaw strengths are distributed normally and that the statistical parameters that were derived are the true ones. In a second step, the conventional method of estimation of Weibull parameters was applied to these sets of data and, then, to subsets selected randomly. The influence of other factors involved in the conventional method of determination of statistical parameters is discussed. It is demonstrated that selection of specimens, sample size, and method of construction of so-called Weibull plots are responsible for statistical parameters variability.
Isospin properties of electric dipole excitations in 48 Ca
Derya, V.; Savran, D.; Endres, J.; Harakeh, M. N; Hergert, H.; Kelley, J.H.; Papakonstantinou, P.; Pietralla, N.; Ponomarev, V. Yu.; Roth, R.; Rusev, G.; Tonchev, A. P.; Tornow, W; Wörtche, H. J.; Zilges, A.
2014-01-01
Two different experimental approaches were combined to study the electric dipole strength in the doubly-magic nucleus 48 Ca below the neutron threshold. Real-photon scattering experiments using bremsstrahlung up to 9.9 MeV and nearly mono-energetic linearly polarized photons with energies between 6.6 and 9.51 MeV provided strength distribution and parities, and an (α,α′γ) experiment at Eα=136MeV gave cross sections for an isoscalar probe. The unexpected difference observed in the dipole respo...
Shear strength and stress distribution in wet granular media
Richefeu, Vincent; Radjaï, Farhang; El Youssoufi, Moulay Saïd
2009-06-01
We investigate the shear strength and stress distribution properties of wet granular media in the pendular state where the liquid is mainly in the form of capillary bonds between particles. This work is based on a 3D discrete-element approach (molecular dynamics) with spherical particles enriched by a capillary force law. We show that the capillary force can be expressed as an explicit function of the gap and volume of the liquid bridge. The length scales involved in this expression are analyzed by comparing with direct integration of the Laplace-Young equation. In the simulations, we consider a maximum number density of liquid bonds in the bulk in agreement with equilibrium of each liquid bridge. This liquid bond number is a decisive parameter for the overall cohesion of wet granular materials. It is shown that the shear strength can be expressed as a function of liquid bond characteristics. The expression proposed initially by Rumpf is thus generalized to account for size polydispersity We show that this expression is in good agreement with our experimental data that will be briefly described. At low confining stress, the tensile action of capillary bonds induces a self-stressed particle network organized in a bi-percolating structure of positive and negative particle pressures. Various statistical descriptors of the microstructure and bond force network are used to characterize this partition. Two basic properties emerge: (i) The highest particle pressure is located in the bulk of each phase (positive and negative particle pressures); (ii) The lowest pressure level occurs at the interface between the two phases, involving also the largest connectivity of the particles via tensile and compressive bonds.
Van de Kamer, JB; Lagendijk, JJW
2002-01-01
SAR distributions in a healthy female adult head as a result of a radiating vertical dipole antenna (frequency 915 MHz) representing a hand-field mobile phone have been computed for three different resolutions: 2 mm, 1 mm and 0.4 mm. The extremely high resolution of 0.4 mm was obtained with our quas
YANG Yun-tao; SHI Zhi-yong; L(U) Jian-gang; GUAN Zhen-zhen
2009-01-01
The interference of carrier magnetic field to geomagnetic field has been a difficult problem for a long time, which influences on the deviation of navigation compass and the error of geomagnetic measurement. To increase the geomagnetic measuring accuracy required for the geomagnetic matching localization, the strategy to eliminate the effect of connatural and induced magnetic fields of carrier on the geomagnetic measuring accuracy is investigated. The magnetic-dipoles magnetic field distributing theory is used to deduce the magnetic composition in the position of the sensor installed on the carrier. A geomagnetic measurement model is established by using the measuring data with the ideal sensor. Considering the magnetic disturbance of carrier and the error of sensor, a geomagnetic measuring compensation model is built. This model can be used to compensate the errors of carrier magnetic field and magnetic sensor in any case and its parameters have clear or specific physical meaning. The experimented results show that the model has higher geomagnetic measuring accuracy than that of others.
Regulation of Cell Adhesion Strength by Peripheral Focal Adhesion Distribution
2011-01-01
Cell adhesion to extracellular matrices is a tightly regulated process that involves the complex interplay between biochemical and mechanical events at the cell-adhesive interface. Previous work established the spatiotemporal contributions of adhesive components to adhesion strength and identified a nonlinear dependence on cell spreading. This study was designed to investigate the regulation of cell-adhesion strength by the size and position of focal adhesions (FA). The cell-adhesive interfac...
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.
Konn, Daniel; Gowland, Penny; Bowtell, Richard
2003-07-01
To investigate the feasibility of direct MR detection of neuronal activity in the brain, neuronal current flow was modeled as an extended current dipole located in a conducting sphere. The spatially varying magnetic field induced within the sphere by such a dipole was calculated, including its form close to and within the current source. The predicted field variation was experimentally verified by measurements of the variation in phase of the MR signal in a sphere containing a model dipole. The effects of the calculated magnetic field distributions on the phase and magnitude of the signal in MR images were explored. The minimum detectable dipole strength under normal experimental conditions was calculated to be about 4.5 nAm, which is similar in magnitude to dipole strengths from evoked neuronal activity, and is an order of magnitude smaller than dipole strengths expected from spontaneous activity. This minimum detectable dipole strength increases with increasing spatial extent of the primary current distribution. In the experimental work, the effects of a field of [1.1 +/- 0.5] x 10(-10) T strength were detected, corresponding to the maximum net field caused by a dipole of 6.3 nAm strength with a spatial extent of 3 x 3 x 2 mm(3). Copyright 2003 Wiley-Liss, Inc.
Regulation of cell adhesion strength by peripheral focal adhesion distribution.
Elineni, Kranthi Kumar; Gallant, Nathan D
2011-12-21
Cell adhesion to extracellular matrices is a tightly regulated process that involves the complex interplay between biochemical and mechanical events at the cell-adhesive interface. Previous work established the spatiotemporal contributions of adhesive components to adhesion strength and identified a nonlinear dependence on cell spreading. This study was designed to investigate the regulation of cell-adhesion strength by the size and position of focal adhesions (FA). The cell-adhesive interface was engineered to direct FA assembly to the periphery of the cell-spreading area to delineate the cell-adhesive area from the cell-spreading area. It was observed that redistributing the same adhesive area over a larger cell-spreading area significantly enhanced cell-adhesion strength, but only up to a threshold area. Moreover, the size of the peripheral FAs, which was interpreted as an adhesive patch, did not directly govern the adhesion strength. Interestingly, this is in contrast to the previously reported functional role of FAs in regulating cellular traction where sizes of the peripheral FAs play a critical role. These findings demonstrate, to our knowledge for the first time, that two spatial regimes in cell-spreading area exist that uniquely govern the structure-function role of FAs in regulating cell-adhesion strength.
Saurabh D Rindani
2003-07-01
In the presence of an electric dipole coupling of $t\\overline{t}$ to a photon, and an analogous `weak’ dipole coupling to the , CP violation in the process +- → $t\\overline{t}$ results in modiﬁed polarization of the top and the anti-top. This polarization can be analyzed by studying the angular distributions of decay charged leptons when the top or anti-top decays leptonically. Analytic expressions are presented for these distributions when either or $\\overline{t}$ decays leptonically, including $\\mathscr{O}(_{s})$ QCD corrections in the soft-gluon approximation. The angular distributions are insensitive to anomalous interactions in top decay. Two types of simple CP-violating polar-angle asymmetries and two azimuthal asymmetries, which do not need the full reconstruction of the or $\\overline{t}$, are studied. Independent 90% CL limits that may be obtained on the real and imaginary parts of the electric and weak dipole couplings at a linear collider operating at $\\sqrt{s}=500$ GeV with integrated luminosity 500 fb-1 and also at $\\sqrt{s} = 1000$ GeV with integrated luminosity 1000 fb-1 have been evaluated. The effect of longitudinal electron and/or positron beam polarizations has been included.
Hosaka, K [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Adachi, J [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Photon Factory, Institute of Materials Structure Science, Tsukuba-shi, Ibaraki 305-0801 (Japan); Golovin, A V [Photon Factory, Institute of Materials Structure Science, Tsukuba-shi, Ibaraki 305-0801 (Japan); Institute of Physics, St Petersburg State University, 198504 St Petersburg (Russian Federation); Takahashi, M [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Teramoto, T [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Watanabe, N [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Yagishita, A [Department of Chemistry, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Photon Factory, Institute of Materials Structure Science, Tsukuba-shi, Ibaraki 305-0801 (Japan); Semenov, S K [State University of Aerospace Instrumentation, 190000 St Petersburg (Russian Federation); Cherepkov, N A [State University of Aerospace Instrumentation, 190000 St Petersburg (Russian Federation)
2006-01-28
Measurements and calculations of the contribution of the non-dipole terms in the angular distribution of photoelectrons from the K-shell of randomly oriented N{sub 2} molecules are reported. The angular distributions have been measured in the plane containing the photon polarization and the photon momentum vectors of linearly polarized radiation. Calculations have been performed in the relaxed core Hartree-Fock approximation with a fractional charge, and many-electron correlations were taken into account in the random phase approximation. Both theory and experiment show that the non-dipole effects are rather small in the photon energy region from the ionization threshold of the K-shell up to about 70 eV above it. From the theory, it follows that the non-dipole terms for the individual 1{sigma}{sub g} and 1{sigma}{sub u} shells are considerably large; therefore measurements resolving the contributions of the 1{sigma}{sub g} and 1{sigma}{sub u} shells are desirable. (letter to the editor)
Fermion Dipole Moment and Holography
Kulaxizi, Manuela
2015-01-01
In the background of a charged AdS black hole, we consider a Dirac particle endowed with an arbitrary magnetic dipole moment. For non-zero charge and dipole coupling of the bulk fermion, we find that the dual boundary theory can be plagued with superluminal modes. Requiring consistency of the dual CFT amounts to constraining the strength of the dipole coupling by an upper bound. We briefly discuss the implications of our results for the physics of holographic non-Fermi liquids.
Pauling bond strength, bond length and electron density distribution
Gibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.; Iversen, Bo B.; Spackman, M. A.
2014-01-18
A power law regression equation, /r)-0.21, determined for a large number of oxide crystals at ambient conditions and /r)-0.22, determined for geometry optimized hydroxyacid molecules, that connect the bond lengths to the average Pauling electrostatic bond strength, , for the M-O bonded interactions. On the basis of the correspondence between the two sets of equations connecting ρ(rc) and the Pauling bond strength s with bond length, it appears that Pauling’s simple definition of bond strength closely mimics the accumulation of the electron density between bonded pairs of atoms. The similarity of the expressions for the crystals and molecules is compelling evidence that the M-O bonded interactions for the crystals and molecules 2 containing the same bonded interactions are comparable. Similar expressions, connecting bond lengths and bond strength, have also been found to hold for fluoride, nitride and sulfide molecules and crystals. The Brown-Shannon bond valence, σ, power law expression σ = [R1/(R(M-O)]N that has found wide use in crystal chemistry, is shown to be connected to a more universal expression determined for oxides and the perovskites, <ρ(rc)> = r[(1.41)/
Magnetic dipole states in /sup 206/Pb
Ponomarev, V.; Vdovin, A.; Velchev, Ch.
1987-12-01
The fragmentation of the magnetic dipole strength in /sup 206/Pb is studied in the framework of the quasiparticle-phonon nuclear model. The calculations reproduce the two-humped shape of the experimental distribution. As in /sup 208/Pb there is an isoscalar 1/sup +/ state at Esub(x) approx. = 5.7 MeV in /sup 206/Pb and its wavefunction contains sizable two-photon components. It is shown that direct transitions from the ground state to two-phonon 1/sup +/ states give a negligible contribution to the total excitation probability of the M1 resonance.
Specimen type and size effects on lithium hydride tensile strength distributions
Oakes, Jr, R E
1991-12-01
Weibull's two-parameter statistical-distribution function is used to account for the effects of specimen size and loading differences on strength distributions of lithium hydride. Three distinctly differing uniaxial specimen types (i.e., an elliptical-transition pure tensile specimen, an internally pressurized ring tensile, and two sizes of four-point-flexure specimens) are shown to provide different strength distributions as expected, because of their differing sizes and modes of loading. After separation of strengths into volumetric- and surface-initiated failure distributions, the Weibull characteristic strength parameters for the higher-strength tests associated with internal fracture initiations are shown to vary as predicted by the effective specimen volume Weibull relationship. Lower-strength results correlate with the effective area to much lesser degree, probably because of the limited number of surface-related failures and the different machining methods used to prepare the specimen. The strength distribution from the fourth specimen type, the predominantly equibiaxially stressed disk-flexure specimen, is well below that predicted by the two-parameter Weibull-derived effective volume or surface area relations. The two-parameter Weibull model cannot account for the increased failure probability associated with multiaxial stress fields. Derivations of effective volume and area relationships for those specimens for which none were found in the literature, the elliptical-transition tensile, the ring tensile, and the disk flexure (including the outer region), are also included.
Jackman, T. M.; Morgan, S. R.; Barest, G. D.; Morgan, E. F.
2015-01-01
Summary This study's goal was to determine associations among the intravertebral heterogeneity in bone density, bone strength, and intervertebral disc (IVD) health. Results indicated that predictions of vertebral strength can benefit from considering the magnitude of the density heterogeneity and the congruence between the spatial distribution of density and IVD health. Introduction This study aims to determine associations among the intravertebral heterogeneity in bone density, bone strength, and IVD health Methods Regional measurements of bone density were performed throughout 30 L1 vertebral bodies using microcomputed tomography (μCT) and quantitative computed tomography (QCT). The magnitude of the intravertebral heterogeneity in density was defined as the interquartile range and quartile coefficient of variation in regional densities. The spatial distribution of density was quantified using ratios of regional densities representing different anatomical zones (e.g., anterior to posterior regional densities). Cluster analysis was used to identify groups of vertebrae with similar spatial distributions of density. Vertebral strength was measured in compression. IVD health was assessed using two scoring systems. Results QCT- and μCT-based measures of the magnitude of the intravertebral heterogeneity in density were strongly correlated with each other (p<0.005). Accounting for the interquartile range in regional densities improved predictions of vertebral strength as compared to predictions based only on mean density (R2=0.59 vs. 0.43; F-test p-value=0.018). Specifically, after adjustment for mean density, vertebral bodies with greater heterogeneity in density exhibited higher strength. No single spatial distribution of density was associated with high vertebral strength. Analyses of IVD scores suggested that the health of the adjacent IVDs may modulate the effect of a particular spatial distribution of density on vertebral strength. Conclusions Noninvasive
Estrada, Nicolas
2016-12-01
Using discrete element methods, the effects of the grain size distribution on the density and the shear strength of frictionless disk packings are analyzed. Specifically, two recent findings on the relationship between the system's grain size distribution and its rheology are revisited, and their validity is tested across a broader range of distributions than what has been used in previous studies. First, the effects of the distribution on the solid fraction are explored. It is found that the distribution that produces the densest packing is not the uniform distribution by volume fractions as suggested in a recent publication. In fact, the maximal packing fraction is obtained when the grading curve follows a power law with an exponent close to 0.5 as suggested by Fuller and Thompson in 1907 and 1919 [Trans Am. Soc. Civ. Eng. 59, 1 (1907) and A Treatise on Concrete, Plain and Reinforced (1919), respectively] while studying mixtures of cement and stone aggregates. Second, the effects of the distribution on the shear strength are analyzed. It is confirmed that these systems exhibit a small shear strength, even if composed of frictionless particles as has been shown recently in several works. It is also found that this shear strength is independent of the grain size distribution. This counterintuitive result has previously been shown for the uniform distribution by volume fractions. In this paper, it is shown that this observation keeps true for different shapes of the grain size distribution.
Ogawa, Yutaro; Ikeda, Akira; Kotani, Kiyoshi; Jimbo, Yasuhiko
In this study, we propose the EEG phase synchronization analysis including not only the average strength of the synchronization but also the distribution and directions under the conditions that evoked emotion by musical stimuli. The experiment is performed with the two different musical stimuli that evoke happiness or sadness for 150 seconds. It is found that the average strength of synchronization indicates no difference between the right side and the left side of the frontal lobe during the happy stimulus, the distribution and directions indicate significant differences. Therefore, proposed analysis is useful for detecting emotional condition because it provides information that cannot be obtained only by the average strength of synchronization.
J. Gogoi
2012-01-01
Full Text Available This paper deals with the stress vs. strength problem incorporating multi-componentsystems viz. standby redundancy. The models developed have been illustrated assuming that allthe components in the system for both stress and strength are independent and follow differentprobability distributions viz. Exponential, Gamma and Lindley. Four different conditions forstress and strength have been considered for this investigation. Under these assumptions thereliabilities of the system have been obtained with the help of the particular forms of densityfunctions of n-standby system when all stress-strengths are random variables. The expressions forthe marginal reliabilities R(1, R(2, R(3 etc. have been derived based on its stress- strengthmodels. Then the corresponding system reliabilities Rn have been computed numerically andpresented in tabular forms for different stress-strength distributions with different values of theirparameters. Here we consider n 3 for estimating the system reliability R3.
Dipoles, unintentional antennas and EMC
Berend Danker
2008-01-01
Full Text Available Radiated emissions from equipment commonly originate from electronic circuits that act as electric dipoles created by the signal voltage between the signal conductors or as magnetic dipoles formed by the signal current flowing in a loop. Direct emission is mostly small, but circuits often couple to long conductors or large wiring loops which act as antennas and are efficient radiators. A comparable situation exists when short dipole antennas or small wiring loops receive ambient noise (susceptibility. Usually the amplitude of noise sources or the susceptibility of circuits is an invariable. The dipole strength increases with the distance between the conductors and the area. Shielding and proper grounding decreases the interaction via unintentional antennas. Short-circuiting and the insertion of lossy ferrite cores reduce the efficiency of unintentional antennas.
Sukhovoj, A. M.; Furman, W. I.; Khitrov, V. A.
2008-06-01
The sums of radiative strength functions for primary dipole gamma transitions, k( E1) + k( M1), are approximated to a high precision by a superposition of two functional dependences in the energy range 0.5 125Te, 128I, 137,138,139Ba, 140La, 150Sm, 156,158Gd, 160Tb, 163,164,165Dy, 166Ho, 168Er, 170Tm, 174Yb, 176,177Lu, 181Hf, 182Ta, 183,184,185,187W, 188,190,191,193Os, 192Ir, 196Pt, 198Au, and 200Hg nuclei. It is shown that, in any nuclei, radiative strength functions are a dynamical quantity and that the values of k( E1) + k( M1) for specific energies of gamma transitions and specific nuclei are determined by the structure of decaying and excited levels, at least up to the neutron binding energy B n .
THE STRENGTH OF THE DISSOLVED OXYGEN MAXIMUM IN THE VERTICAL DISTRIBUTION OF N ANSHA ISLANDS WATERS
林洪瑛; 程赛伟; 韩舞鹰
2002-01-01
Observation data from a cruise in the Nansha Islands, in May to June 1990, Decem ber, 1993, September to October 1994, and July, 1999, respectively, were used to develop the method presented here to indicate the existing strength of the diss ol ved oxygen maximum in the vertical distribution of Nansha Islands waters. Its se asonal variation and regional distribution are discussed in this paper. Analysis results showed that the distribution of the strength of dissolved oxygen maximum (Domax-Dosur) was closely related to the upper layer circulation and the bioactivity of Nansha Islands seawater.
Experimental results on the Pygmy Dipole Resonance
Savran Deniz
2014-03-01
Full Text Available The so-called Pygmy Dipole Resonance, an additional structure of low-lying electric dipole strength, has attracted strong interest in the last years. Different experimental approaches have been used in the last decade in order to investigate this new interesting nuclear excitation mode. In this contribution an overview on the available experimental data is given.
Modified Weibull Distribution for Analyzing the Tensile Strength of Bamboo Fibers
Fang Wang
2014-12-01
Full Text Available There is growing evidence that the standard Weibull strength distribution is not always accurate for the description of variability in tensile strength and its dependence on the gauge size of brittle fibers. In this work, a modified Weibull model by incorporating the diameter variation of bamboo fiber is proposed to investigate the effect of fiber length and diameter on the tensile strength. Fiber strengths are obtained for lengths ranging from 20 to 60 mm and diameters ranging from 196.6 to 584.3 μm through tensile tests. It is shown that as the within-fiber diameter variation increases, the fracture strength of the bamboo fiber decreases. In addition, the accuracy of using weak-link scaling predictions based on the standard and modified Weibull distribution are assessed, which indicates that the use of the modified distribution provides better correlation with the experimental data than the standard model. The result highlights the accuracy of the modified Weibull model for characterizing the strength and predicting the size dependence of bamboo fiber.
Numerical simulation of temperature and strength distributions of mold(core) on heating
无
2001-01-01
By using Visual C+ +, a model with post-processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256-color graphic mode. With this model, the temperature and strength distributions of the mold(core) both in case of heating process for core in the furnace and solidification process for a thin-wall aluminum alloy casting in the mold(core) are numerically simulated. The results show that the temperature and strength distributions of the mold(core) were uneven because the thermal conductivity of the resin sand was much small. This study laid a basis for the optimum design of the mold(core) properties.
Axion Induced Oscillating Electric Dipole Moments
Hill, Christopher T
2015-01-01
The axion electromagnetic anomaly induces an oscillating electric dipole for any static magnetic dipole. Static electric dipoles do not produce oscillating magnetic moments. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency $m_a$ and strength $\\sim 10^{-32}$ e-cm, two orders of magnitude above the nucleon, and within four orders of magnitude of the present standard model DC limit. This may suggest sensitive new experimental venues for the axion dark matter search.
Size effect on strength and lifetime probability distributions of quasibrittle structures
Zdeněk P Bažant; Jia-Liang Le
2012-02-01
Engineering structures such as aircraft, bridges, dams, nuclear containments and ships, as well as computer circuits, chips and MEMS, should be designed for failure probability < $10^{-6}-10^{-7}$ per lifetime. The safety factors required to ensure it are still determined empirically, even though they represent much larger and much more uncertain corrections to deterministic calculations than do the typical errors of modern computer analysis of structures. The empirical approach is sufﬁcient for perfectly brittle and perfectly ductile structures since the cumulative distribution function (cdf) of random strength is known, making it possible to extrapolate to the tail from the mean and variance. However, the empirical approach does not apply to structures consisting of quasibrittle materials, which are brittle materials with inhomogeneities that are not negligible compared to structure size. This paper presents a reﬁned theory on the strength distribution of quasibrittle structures, which is based on the fracture mechanics of nanocracks propagating by activation energy controlled small jumps through the atomic lattice and an analytical model for the multi-scale transition of strength statistics. Based on the power law for creep crack growth rate and the cdf of material strength, the lifetime distribution of quasibrittle structures under constant load is derived. Both the strength and lifetime cdfs are shown to be sizeand geometry-dependent. The theory predicts intricate size effects on both the mean structural strength and lifetime, the latter being much stronger. The theory is shown to match the experimentally observed systematic deviations of strength and lifetime histograms of industrial ceramics from the Weibull distribution.
Coherent manipulation of two dipole-dipole interacting ions
Beige, A; Knight, P L; Plenio, M B; Thompson, R C
2000-01-01
We investigate to what extent two trapped ions can be manipulated coherently when their coupling is mediated by a dipole-dipole interaction. We will show how the resulting level shift induced by this interaction can be used to create entanglement, while the decay of the states remains nearly negligible. This will allow us to implement conditional dynamics (a CNOT gate) and single qubit operations. We propose two different experimental realisations where a large level shift can be achieved and discuss both the strengths and weaknesses of this scheme from the point of view of a practical realization.
Gammelmark, Søren; Zinner, Nikolaj Thomas
2013-01-01
We study polar molecules with long-range dipole-dipole interactions confined to move on a two-leg ladder for different orientations of the molecular dipole moments with respect to the ladder. Matrix product states are employed to calculate the many-body ground state of the system as function...... of lattice filling fractions, perpendicular hopping between the legs, and dipole interaction strength. We show that the system exhibits zig-zag ordering when the dipolar interactions are predominantly repulsive. As a function of dipole moment orientation with respect to the ladder, we find...... that there is a critical angle at which ordering disappears. This angle is slightly larger than the angle at which the dipoles are non-interacting along a single leg. This behavior should be observable using current experimental techniques....
Effects of Horizontal Density Distribution on Internal Bond Strength of Flakeboard
MEIChangtong; DAIChunping; ZHOUDingguo
2005-01-01
Horizontal density variation is a structural phenomenon of non-veneer wood composites. The variation and distribution characteristics of horizontal density have impacts on the products properties. In this study, veneer strip simulated flake boards with 4 kinds of density distribution were made using a mat model. The density variation of the modeled mats was discussed, as well as the relationship between sample size and density variation. The effects of density and density distribution of non-veneer composites on the internal bond strength were analyzed. Result shows that the horizontal density of random formed particleboard follows normal distribution. Density has remarkable influence on internal bond strength (IB). Increasing density helps to improve IB at lower density stage, but has negative impacts on IB at higher density stage.Density variation between testing specimens depends on their sizes. Properly increasing specimen size can decrease the variation of the IBs.
Zhou, H. W.; Mishnaevsky, Leon; Yi, H. Y.;
2016-01-01
The strength and fracture behavior of carbon fiber reinforced polymer composites with carbon nanotube (CNT) secondary reinforcement are investigated experimentally and numerically. Short Beam Shearing tests have been carried out, with SEM observations of the damage evolution in the composites. 3D...... multiscale computational (FE) models of the carbon/polymer composite with varied CNT distributions have been developed and employed to study the effect of the secondary CNT reinforcement, its distribution and content on the strength and fracture behavior of the composites. It is shown that adding secondary...... CNT nanoreinforcement into the matrix and/or the sizing of carbon fiber/reinforced composites ensures strong increase of the composite strength. The effect of secondary CNTs reinforcement is strongest when some small addition of CNTs in the polymer matrix is complemented by the fiber sizing with high...
Distribution of photon strength in nuclei by a method of two-step cascades
Becvar, F.; Cejnar, P. (Karlova Univ., Prague (Czechoslovakia). Fakulta Matematicko-Fyzikalni); Chrien, R.E. (Brookhaven National Lab., Upton, NY (USA)); Kopecky, J. (Netherlands Energy Research Foundation, Petten (Netherlands))
1990-01-01
The applicability of sum-coincidence measurements of two-step cascade {gamma}-ray spectra to the determination of photon strength functions at intermediate {gamma}-ray energies (3 or 4 MeV) is discussed. An experiment based on thermal neutron capture in Nd was undertaken at the Brookhaven National Laboratory High Flux Beam Reactor to test this model. To understand the role of various uncertainties in similar experiments a series of model calculations was performed. We present an analysis of our experimental data which demonstrates the high sensitivity of the method to E1 and M1 photon strength functions. Our experimental data are in sharp contradiction to those expected from an E1 photon strength distributed according to the classical Lorentzian form with an energy invariant damping width. An alternative distribution of Kadmenskij et al., which violates Brink's Hypothesis, is strongly preferred. 13 refs., 5 figs.
Strength distribution of solar magnetic fields in photospheric quiet Sun regions
Ramírez Vélez, J. C.; López Ariste, A.; Semel, M.
2008-08-01
Context: The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed Mn i line at 553.7 nm, allows such differentiation. Aims: To analyse the distribution of field strengths in the network and intranetwork of the solar photosphere through inversion of the Mn i line at 553.7 nm. Methods: An inversion code for the magnetic field using the principal component analysis (PCA) has been developed. Statistical tests are run on the code to validate it. The code has to draw information from the small-amplitude spectral feature appearing in the core of the Stokes V profile of the observed line for field strengths below a certain threshold, coinciding with lower limit of the Paschen-Back effect in the fine structure of the involved atomic levels. Results: The inversion of the observed profiles, using the circular polarisation (V) and the intensity (I), shows the presence of magnetic fields strengths in a range from 0 to 2 kG, with predominant weak strength values. Mixed regions with mean strength field values of 1130 and 435 Gauss are found associated with the network and intranetwork, respectively. Conclusions: The Mn i line at 553 nm probes the field strength distribution in the quiet sun and shows the predominance of weak, hectoGauss fields in the intranetwork, and strong, kiloGauss fields in the network. It also shows that both network and intranetwork are to be understood at our present spatial resolutions as field distributions, of which we hint at the mean properties.
Sukhovoj, A M; Khitrov, V A
2008-01-01
The sums k(E1)+k(M1) of radiative strength functions of dipole primary gamma-transitions were approximated with high precision in the energy region of $0.5 < E_1 < B_n-0.5$ MeV for nuclei: 40K, 60Co, 71,74Ge, 80Br, 114Cd, 118Sn, 124,125Te, 128I, 137,138,139Ba, 140La, 150Sm, 156,158Gd, 160Tb, 163,164,165Dy, 166Ho, 168Er, 170Tm, 174Yb, 176,177Lu, 181Hf, 182Ta, 183,184,185,187W, 188,190,191,193Os, 192Ir, 196Pt, 198Au, 200Hg by sum of two independent functions. It has been shown that this parameter of gamma-decay are determined by the structure of the decaying and excited levels, at least, up to the neutron binding energy.
Spin dipole and quadrupole resonances in sup 40 Ca
Baker, F.T.; Love, W.G. (The University of Georgia, Athens, GA (USA)); Bimbot, L. (The University of Paris, Orsay, (France)); Fergerson, R.W.; Glashausser, C.; Green, A. (Rutgers University, New Brunswick, NJ (USA)); Jones, K. (Los Alamos National Laboratory, Los Alamos, NM (USA)); Nanda, S. (Continuous Electron Beam Accelerator Facility, Newport News, VA (USA) The University of Georgia, Athens, GA (USA))
1989-11-01
Angular distributions of the double differential cross section {ital d}{sup 2}{sigma}/d{Omega} dE({sigma}) and the spin-flip probability {ital S}{sub {ital nn}} have been measured for inclusive proton inelastic scattering from {sup 40}Ca at 319 MeV. Excitation energies ({omega}) up to about 40 MeV have been investigated over the angular range from 3.5{degree} to 12{degree} in the laboratory (0.3 to 0.9 fm{sup {minus}1}). Here, multipole decompositions of angular distributions of {sigma}{ital S}{sub {ital nn}} for the {sup 40}Ca({ital {rvec p}},{ital {rvec p}} {prime}) reaction at 319 MeV have been performed in order to compare {Delta}{ital S}=1 strength observed with sum rules. In contrast to the well-known quenching of Gamow-Teller and {ital M}1 resonances, the spin-dipole resonance has a total measured strength which is larger than that predicted by the energy-weighted sum rule. The spin-dipole strength distribution supports asymmetric widths predicted by calculations including 2p-2h mixing. The spin-quadrupole resonance is observed near {omega}=35 MeV and its total strength for {omega}{lt}40 MeV estimated.
Kielgast, Mathias Rønholt; Rasmussen, Anders Charly; Laursen, Mathias Hjorth
2016-01-01
This letter presents an experimental study and a novel modelling approach of the wireless channel of smart utility meters placed in basements or sculleries. The experimental data consist of signal strength measurements of consumption report packets. Since such packets are only registered if they ......This letter presents an experimental study and a novel modelling approach of the wireless channel of smart utility meters placed in basements or sculleries. The experimental data consist of signal strength measurements of consumption report packets. Since such packets are only registered...... if they can be decoded by the receiver, the part of the signal strength distribution that falls below the receiver sensitivity threshold is not observable. We combine a Rician fading model with a bias function that captures the cut-off in the observed signal strength measurements. Two sets of experimental...... data are analysed. It is shown that the proposed method offers an approximation of the distribution of the signal strength measurements that is better than a naïve Rician fitting....
Protsenko, I E; Uskov, A V; Krotova, K E [Lebedev Physical Institute, Leninsky prospect 53, Moscow (Russian Federation); O' Reilly, E P [Tyndall National Institute, ' Lee Maltings' , Prospect Row, Cork (Ireland)], E-mail: protsen@sci.lebedev.ru, E-mail: protsenk@gmail.com
2008-03-15
Theoretically predicted 'dipole lasing', i.e., spontaneous excitation of coherent metal nano-particle dipole oscillations through interaction with a quantum-dot two-level system subject to population inversion is demonstrated. Equations for dipole lasing are the same as equations for ordinary laser, where the dipole momentum of nano-particle stands for the electromagnetic field cavity mode. Dipole lasing frequency corresponds to the localized plasmon resonance of the nano-particle. Dipole momentum of nano-particle leads to coherent dipole radiation. Optical cavity is not necessary, the size of the dipole laser can be smaller than the optical wavelength, i.e. it is dipole nano-laser. Threshold conditions and optical bistability in dipole nano-lasers are considered.
Nadykto, Alexey B; Yu, Fangqun
2008-08-07
Sulfuric acid is a primary atmospheric nucleation precursor, with the ability to form stable aqueous hydrogen-bonded clusters/complexes. The electrical dipole moment of such clusters/complexes is important for ion-induced nucleation, largely controlled by dipole-charge interaction of airborne ions with vapor monomers and pre-existing clusters. Although experiments typically trace a single lowest energy conformer at low temperatures, the present study shows that the immediate vicinity (dipole moments. The difference in the dipole moment of mono-, di-, and trihydrates of the sulfuric acid exceeds 1.3-1.5 Debyes ( approximately 50-60%), 1.4-2.6 Debyes ( approximately 50-90%), and 3.8-4.2 Debyes ( approximately 370-550%), respectively. Being driven by the temperature dependence of the Boltzmann distribution, the difference between the Boltzmann-Gibbs average dipole moment and the dipole moment of the most stable isomer increases with the ambient temperature, leading to large variations in the dipole-ion interaction strength, which may have important implications for the ion-mediated production of ultrafine aerosol particles associated with various climatic and health impacts.
Guo, Shanzeng; Tang, Helen
2012-05-01
Future military wireless communication in a battlefield will be mobile ad hoc in nature. The ability to geolocate and track both friendly forces and enemies is very important in military command and control operations. However, current mobile ad hoc networks (MANET) have no capabilities to geolocate radio emitters that belong to enemy mobile ad hoc networks. This paper presents a distributed geolocation algorithm using received signal strength differences to geolocate enemy radio emitters by leveraging friendly force MANET infrastructure, and proposes a communication protocol for radio emitter geolocation applications. An enemy's radio emitter signal is detected, and its signal strength is measured by the nodes in a friendly mobile ad hoc network. The identity of the enemy radio emitter is extracted from the decoded message header of the medium access control layer. By correlating and associating the enemy's radio emitter identity with its received signal strength, the enemy radio emitter is identified. The enemy's radio emitter identity and its received signal strength are distributed and shared among friendly mobile ad hoc nodes. Using received signal strength differences, a master friendly node can calculate the enemy's radio emitter geolocation, and build a recognized MANET picture (RMP). This MANET picture is then distributed to all friendly nodes for effective command and control operations. An advantage of this method is that mobile ad hoc nodes do not need special RF antennas to geolocate the enemy radio emitter as conventional electronic warfare techniques do. MATLAB-based simulations are presented to evaluate the accuracy and reliability of the proposed distributed geolocation algorithm under different MANET placements.
Direct summation of dipole-dipole interactions using the Wolf formalism.
Stenqvist, Björn; Trulsson, Martin; Abrikosov, Alexei I; Lund, Mikael
2015-07-07
We present an expanded Wolf formalism for direct summation of long-range dipole-dipole interactions and rule-of-thumbs how to choose optimal spherical cutoff (Rc) and damping parameter (α). This is done by comparing liquid radial distribution functions, dipole-dipole orientation correlations, particle energies, and dielectric constants, with Ewald sums and the Reaction field method. The resulting rule states that ασ 3 for reduced densities around ρ(∗) = 1 where σ is the particle size. Being a pair potential, the presented approach scales linearly with system size and is applicable to simulations involving point dipoles such as the Stockmayer fluid and polarizable water models.
Low-energy electric dipole response in 120Sn
Krumbholz, A M; Hashimoto, T; Tamii, A; Adachi, T; Bertulani, C A; Fujita, H; Fujita, Y; Ganioglu, E; Hatanaka, K; Iwamoto, C; Kawabata, T; Khai, N T; Krugmann, A; Martin, D; Matsubara, H; Neveling, R; Okamura, H; Ong, H J; Poltoratska, I; Ponomarev, V Yu; Richter, A; Sakaguchi, H; Shimbara, Y; Shimizu, Y; Simonis, J; Smit, F D; Susoy, G; Thies, J H; Suzuki, T; Yosoi, M; Zenihiro, J
2015-01-01
Electric dipole strength in 120Sn below the neutron threshold has been extracted from proton inelastic scattering experiments at E_p = 295 MeV and at forward angles including 0 degree. The strength distribution is very different from the results of a 120Sn(gamma,gamma') experiment and peaks at an excitation energy of 8.3 MeV. The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and is more than three times larger than what is observed with the (gamma,gamma') reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1- states.
YANG Jiu-jun; HAI Ran; DONG Yan-ling; WU Ke-ru
2003-01-01
The effects of the component gradient distribution at interface and the fiber gradient distribution on the strength of cement-based materials were studied.The results show that the flexural strength and compressive strength of the mortar and concrete with interface component and fiber gradient distributions are obviously improved.The strengthes of the fiber gradient distributed mortar and concrete (FGDM/C) are higher than those of fiber homogeneously distributed mortar and concrete (FHDM/C).To obtain the same strength,therefore,a smaller fiber volume content in FGDM/C is needed than that in FHDM/C.The results also show that the component gradient distribution of the concrete can be obtained by means of multi-layer vibrating formation.
Babb, James F
2015-01-01
The dynamic electric dipole polarizability function for the magnesium atom is formed by assembling the atomic electric dipole oscillator strength distribution from combinations of theoretical and experimental data for resonance oscillator strengths and for photoionization cross sections of valence and inner shell electrons. Consistency with the oscillator strength (Thomas-Reiche-Kuhn) sum rule requires the adopted principal resonance line oscillator strength to be several percent lower than the values given in two critical tabulations, though the value adopted is consistent with a number of theoretical determinations. The static polarizability is evaluated. Comparing the resulting dynamic polarizability as a function of photon energy with more elaborate calculations reveals the contributions of inner shell electron excitations. The present results are applied to calculate the long-range interactions between two and three magnesium atoms and the interaction between a magnesium atom and a perfectly conducting m...
Hamák I.
2010-06-01
Full Text Available Residual stresses resulting from non homogeneous heat distribution during welding process belong to most significant factor influencing behavior of welded structures. These stresses are responsible for defect occurrence during welding and they are also responsible for crack initiation and propagation at the either static or dynamic load. The significant effect of weld metal chemical composition as well as the effect of fatigue load and local plastic deformation on residual stress distribution and fatigue life have been recognized for high strength steels welds. The changes in residual stress distribution have then positive effect on cold cracking behavior and also on fatigue properties of the welds [1-3]. Several experimental methods, both destructive and non-destructive, such as hole drilling method, X-ray diffraction, neutron diffraction and others, have been used to examine residual stress distribution in all three significant orientations in the vicinity of the welds. The present contribution summarizes the results of neutron diffraction measurements of residual stress distribution in the vicinity of single-pass high-strength-steel welds having different chemical composition as well as the influence of fatigue load and local plastic deformation. It has been observed that the chemical composition of the weld metal has a significant influence on the stress distribution around the weld. Similarly, by aplying both cyclic load or pre-stress load on the specimens, stress relaxation was observed even in the region of approximately 40 mm far from the weld toe.
The Inverse Problem for the Dipole Field
Epp, V
2015-01-01
The Inverse problem for an electromagnetic field produced by a dipole is solved. It is assumed that the field of an arbitrary changing dipole is known. Obtained formulae allow calculation of the position and dynamics of the dipole which produces the measured field. The derived results can be used in investigations on radiative process in solids caused by changing of the charge distribution. For example, generation of the electromagnetic field caused by oscillations of atoms or electron gas at the trace of a particle channeling in a crystal, or fields arising at solids cracking or dislocation formation -- in any case when one is interested in the details of the dipole field source.
Integral Measurement of Dipole Prototype of CSR
无
2001-01-01
The dipole prototype is C type used as bending magnet of the injection beam line in CSR, and acts as a model of the dipoles in the CSR main ring simultaneously. The designed relative uniformity of good field is 0.001 in 100 mm width. The results of the local distribution and transfunction at transverse profile measured
How to Introduce the Magnetic Dipole Moment
Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.
2012-01-01
We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the…
High-field dipoles for future accelerators
Wipf, S.L.
1984-09-01
This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators.
Dipole polarizability of 120Sn and nuclear energy density functionals
Hashimoto, T; Reinhard, P -G; Tamii, A; von Neumann-Cosel, P; Adachi, T; Aoi, N; Bertulani, C A; Fujita, H; Fujita, Y; Ganioǧlu, E; Hatanaka, K; Iwamoto, C; Kawabata, T; Khai, N T; Krugmann, A; Martin, D; Matsubara, H; Miki, K; Neveling, R; Okamura, H; Ong, H J; Poltoratska, I; Ponomarev, V Yu; Richter, A; Sakaguchi, H; Shimbara, Y; Shimizu, Y; Simonis, J; Smit, F D; Süsoy, G; Thies, J H; Suzuki, T; Yosoi, M; Zenihiro, J
2015-01-01
The electric dipole strength distribution in 120Sn between 5 and 22 MeV has been determined at RCNP Osaka from a polarization transfer analysis of proton inelastic scattering at E_0 = 295 MeV and forward angles including 0{\\deg}. Combined with photoabsorption data an electric dipole polarizability alpha_D(120Sn) = 8.93(36) fm^3 is extracted. The correlation of this value with alpha_D for 208Pb serves as a test of energy density functionals (EDFs). The majority of models based on Skyrme interactions can describe the data while relativistic approaches fail. The accuracy of the experimental results provides important constraints on the static isovector properties of EDFs used to predict symmetry energy parameters and the neutron skin thickness of nuclei.
Axion induced oscillating electric dipole moments
Hill, Christopher T. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2015-06-24
In this study, the axion electromagnetic anomaly induces an oscillating electric dipole for any magnetic dipole. This is a low energy theorem which is a consequence of the space-time dependent cosmic background field of the axion. The electron will acquire an oscillating electric dipole of frequency m_{a} and strength ~ 10^{-32} e-cm, within four orders of magnitude of the present standard model DC limit, and two orders of magnitude above the nucleon, assuming standard axion model and dark matter parameters. This may suggest sensitive new experimental venues for the axion dark matter search.
Strength distribution at interface of rotary-friction-welded aluminum to nodular cast iron
SONG Yu-lai; LIU Yao-hui; ZHU Xian-yong; YU Si-rong; ZHANG Ying-bo
2008-01-01
The morphology, size and composition of intermetallic compound at the interface of Al 1050 and nodular cast iron were studied by electron microprobe analysis(EMPA) and scan electron microscopy (SEM), respectively. The bond strength of the interface was measured by the tensile tests and the morphology of the fracture surface was observed by SEM. The observation of the interface reveals that there are two distinct morphologies: no intermetallic compound exists in the central area at the interface; while numbers of intermetallic compounds (FexAly) are formed in the peripheral area due to the overfull heat input. The tensile tests indicate that the distribution of strength in radial direction at the interface is inhomogeneous, and the central area of the interface performs greater bond strength than the peripheral area, which proves directly that the FexAly intermetallic compounds have a negative effect on the integration of interface. The morphology on the fracture surface shows that the facture in the central area at the interface has characteristic of the ductile micro-void facture. So it is important to restrain the form of the intermetallic compound to increase the bond strength of the Al 1050 and nodular cast iron by optimizing welding parameters and the geometry of components.
Mineev, V. P.
2009-01-01
The roton excitation in the superfluid He-4 does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorpt...
Dao, Diep Bich; Mabbs, Richard, E-mail: mabbs@wustl.edu [Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis 63130 (United States)
2014-10-21
The first photoelectron spectra of AgF{sup −} are recorded over the energy range 1.61–1.85 eV using the velocity map imaging technique. The resolved vibrational structure of the AgF X′, v′ ← AgF{sup −} X″, v″ = 0 band yields an AgF electron affinity of 1.46 ± 0.01 eV and vibrational frequency of 500 ± 40 cm{sup −1}. For the v′ = 2, 3, 4 channels, the photodetachment cross sections and angular distributions undergo rapid changes over a narrow electron kinetic energy range in the region of 50 meV (approximately 13 meV below the opening of the next vibrational channel). This is consistent with Fano-like behavior indicating autodetachment following excitation to a resonant anion state lying in the detachment continuum. EOM-CCSD calculations reveal this to be a dipole bound state. The consistency of the detachment data with the vibrational autodetachment propensity rule Δv = −1 shows that the autodetachment results from breakdown of the Born-Oppenheimer approximation, coupling the vibrational and electronic degrees of freedom.
Kaufman, G.H.
1976-09-01
The General Electric Company was contracted by the Energy Research and Development Administration (ERDA) under contract No. E(49-18) 2157 to study the relationship in distribution transformers between impulse strength and load current. The evaluation of the impulse strength of distribution transformers by a new test technique which simulates in-service functional conditions is described. This unique test procedure includes the effect of different load currents and of rated 60 Hz voltage stress as well as the effect of precipitation cooling. Over 50 distribution transformers with a 15 kV class insulation system were subjected to impulse breakdown tests; approximately one half of these transformers were tested in the new condition. The other half were tested after a loss of life of 50% during accelerated laboratory aging. Specimen transformers representing several USA manufacturers were purchased from five utility stockpiles. The possibility that gas bubble formation and/or accumulation within transformer windings may be a factor contributing to transformer field failures was the subject of another study described. Visual observation and dielectric measurements were made on full-size distribution transformers and on special model coils in order to establish operating conditions which resulted in bubble generation and a possible decrease in insulation breakdown strength. Other data obtained during the aging and loading of sample transformers includes: excitation and impedance losses before and after aging; winding temperatures and estimated hot spot temperatures as a function of load current; and oil characteristics before and after aging. Also described are the results of impulse tests under short-time overload conditions, and some data concerning the effect of moisture in the winding on impulse breakdown.
Mehlhorn, Alexander T; Walther, Markus; Yilmaz, Tayfun
2017-01-01
of life. 17 consecutive patients suffering from a Lisfranc fracture dislocation were registered, underwent open reduction and internal fixation and were followed-up for 50.5±25.7months (Mean±SDM). Biomechanical analysis of muscle strength capacities, postural control and plantar pressure distribution...... correlated well with clinical outcome. Altered postural control was evident by a significant reduction in unilateral stance time, from which we calculated a strong correlation between stance time and the isokinetic strength measurement. Plantar pressure measurements revealed a significant reduction in peak...... pressure under the midfoot and of Force-Time Integral beneath the second metatarsal. Sufficient rehabilitation is crucial to the clinical outcome following anatomical open reduction of Lisfranc fracture-dislocation. The present study supports a rehabilitation approach focussing on restoring proprioception...
Majid, Z.A.; Mahmud, H.; Shaaban, M.G.
1996-12-31
Stabilization/solidification of hazardous wastes is used to convert hazardous metal hydroxide waste sludge into a solid mass with better handling properties. This study investigated the pore size development of ordinary portland cement pastes containing metal hydroxide waste sludge and rice husk ash using mercury intrusion porosimetry. The effects of acre and the addition of rice husk ash on pore size development and strength were studied. It was found that the pore structures of mixes changed significantly with curing acre. The pore size shifted from 1,204 to 324 {angstrom} for 3-day old cement paste, and from 956 to 263 {angstrom} for a 7-day old sample. A reduction in pore size distribution for different curing ages was also observed in the other mixtures. From this limited study, no conclusion could be made as to any correlation between strength development and porosity. 10 refs., 6 figs., 3 tabs.
Low-energy electric dipole response in 120Sn
A.M. Krumbholz
2015-05-01
Full Text Available The electric dipole strength distribution in 120Sn has been extracted from proton inelastic scattering experiments at Ep=295 MeV and at forward angles including 0°. It differs from the results of a Sn120(γ,γ′ experiment and peaks at an excitation energy of 8.3 MeV. The total strength corresponds to 2.3(2% of the energy-weighted sum rule and is more than three times larger than what is observed with the (γ,γ′ reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1− states.
Influences of Randomly Distributed Wall THickness of Beverage Can on Its Strength and Stiffness
XuJing－jing; WANGZhi－ling; 等
2001-01-01
This paper describes the research undertaken on the strength and stiffness of fluctuation on the wall thickness of steel beverage cans using the Monte-Carlo stochastic finite element method.Sample distributions were firestly assumed and then proven using the data observations of the wall thickness.the APDL language was then applied,and the stresses and displacements of the can were calculated by using the ANSYS software.It is concluded that the structureal reliability of a steel-making beverage can be estimated accurately.
Bahman Tarvirdizade
2014-01-01
Full Text Available We consider the estimation of stress-strength reliability based on lower record values when X and Y are independently but not identically inverse Rayleigh distributed random variables. The maximum likelihood, Bayes, and empirical Bayes estimators of R are obtained and their properties are studied. Confidence intervals, exact and approximate, as well as the Bayesian credible sets for R are obtained. A real example is presented in order to illustrate the inferences discussed in the previous sections. A simulation study is conducted to investigate and compare the performance of the intervals presented in this paper and some bootstrap intervals.
Strength distribution of solar magnetic fields in photospheric quiet Sun regions
Velez, J C Ramirez; Semel, M
2008-01-01
The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed MnI line at 553.7 nm, allows such differentiation. The main aim is to analyse the distribution of field strengths in the network and intranetwork of the solar photosphere through inversion of the MnI line at 553.7 nm. An inversion code for the magnetic field using the Principal Component Analysis (PCA) has been developed. Statistical tests are run on the code to validate it. The code has to draw information from the small-amplitude spectral feature oppearing in the core of the Stokes V profile of the observed line for field strengths below a certain threshold, coinciding with lower limit of the Paschen-Back effect in the fine structure of the involved atomic levels. The inversion of the observed profiles,...
Gamow-Teller (GT$\\pm$) strength distributions of $^{56}Ni$ for ground and excited states
Nabi, Jameel-Un; Sajjad, Muhammad
2016-01-01
Gamow-Teller (GT) transitions play an important and consequential role in many astrophysical phenomena. These include, but are not limited to, electron and positron capture rates which determine the fate of massive stars and play an intricate role in the dynamics of core collapse. These $GT_{\\pm}$ transitions rates are the significant inputs in the description of supernova explosions. $GT_{\\pm}$ strength function values are sensitive to the $^{56}Ni$ core excitation in the middle \\textit{pf}-shell region and to the size of the model space as well. We used the pn-QRPA theory for extracting the GT strength for ground and excited states of $^{56}Ni$. We then used these GT strength distributions to calculate the electron \\textit{and} positron capture rates which show differences with the earlier calculations. One curious finding of this paper is our enhanced electron capture rates on $^{56}Ni$ at presupernova temperatures. These differences need to be taken into account for the modeling of the early stages of Typ...
Dzhioev, Alan A; Ponomarev, V Yu; Wambach, J; Langanke, K; Martínez-Pinedo, G
2009-01-01
We propose a new method to calculate stellar weak-interaction rates. It is based on the Thermo-Field-Dynamics formalism and allows the calculation of the weak-interaction response of nuclei at finite temperatures. The thermal evolution of the GT$_+$ distributions is presented for the sample nuclei $^{54, 56}$Fe and ~$^{76,78,80}$Ge. For Ge we also calculate the strength distribution of first-forbidden transitions. We show that thermal effects shift the GT$_+$ centroid to lower excitation energies and make possible negative- and low-energy transitions. In our model we demonstrate that the unblocking effect for GT$_+$ transitions in neutron-rich nuclei is sensitive to increasing temperature. The results are used to calculate electron capture rates and are compared to those obtained from the shell model.
Electric dipole polarizability of $^{48}$Ca and implications for the neutron skin
Birkhan, J; Bacca, S; Bassauer, S; Bertulani, C A; Hagen, G; Matsubara, H; von Neumann-Cosel, P; Papenbrock, T; Pietralla, N; Ponomarev, V Yu; Richter, A; Schwenk, A; Tamii, A
2016-01-01
The electric dipole strength distribution in Ca-48 between 5 and 25 MeV has been determined at RCNP, Osaka, from proton inelastic scattering experiments at forward angles. Combined with photoabsorption data at higher excitation energy, this enables for the first time the extraction of the electric dipole polarizability alpha_D(Ca-48) = 2.07(22) fm^3. Remarkably, the dipole response of Ca-48 is found to be very similar to that of Ca-40, consistent with a small neutron skin in Ca-48. The experimental results are in good agreement with ab initio calculations based on chiral effective field theory interactions and with state-of-the-art density-functional calculations, implying a neutron skin in Ca-48 of 0.14 - 0.20 fm.
Plasmon-Induced Resonant Energy Transfer: a coherent dipole-dipole coupling mechanism
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.
Random matrix analysis of the monopole strength distribution in $^{208}$Pb
Severyukhin, A P; Arsenyev, N N; Nazmitdinov, R G; Pichugin, K N
2016-01-01
We study statistical properties of the $0^+$ spectrum of $^{208}$Pb in the energy region $E_x\\leq20$ MeV. We use the Skyrme interaction SLy4 as our model Hamiltonian to create a single-particle spectrum and to analyze excited states. The finite-rank separable approximation for the particle-hole interaction enables us to perform the calculations in large configuration spaces. We show that while the position of the monopole resonance centroid is determined by one phonon excitations of $0^+$, the phonon-phonon coupling is crucial for the description of a strength distribution of the $0^+$ spectrum. In fact, this coupling has an impact on the spectral rigidity $\\Delta_3(L)$ which is shifted towards the random matrix limit of the Gaussian orthogonal ensembles.
N. Graupner
2016-08-01
Full Text Available The present study focuses on the reprocessing behaviour of recycled injection moulded polylactide (PLA composites. The composites are reinforced with regenerated cellulose fibres (lyocell of variable fineness and a fibre mass content of 30%. They were reprocessed up to three times. The influence of reprocessing on the fibre length distribution and the resulting composite mechanical properties (tensile and impact strength was analysed. While the first reprocessing cycle does not affect the mechanical characteristics of the neat PLA matrix, the strength of the composites decreases significantly due to a decreasing fibre aspect ratio. It was shown that fibres having a larger cross-sectional area display a lower aspect ratio than finer fibres, after reprocessing. This phenomenon leads to a larger decrease in tensile strength of composites reinforced with coarser fibres when compared to composites reinforced with finer fibres. A comparison of virgin composites and threefold reprocessed composites with a similar fibre length distribution resulted in a significantly higher tensile strength compared to the virgin sample. This result leads to the conclusion that not only the fibre length is drastically reduced by reprocessing but also that the fibres and the matrix were damaged.
Strength distribution of fatigue crack initiation sites in an Al-Li alloy
Zhai, T.
2006-10-01
The stress-number of cycles to failure (S-N) curves were measured along the short-transverse (S) and rolling (L) directions of a hot-cross-rolled AA 8090 Al-Li alloy plate (45-mm thick). The alloy was solution heat treated, quenched in water, strained by 6 pct, and peak aged. Fatigue tests were carried out in four-point bend at room temperature, 20 Hz, R=0.1, in air. It was found that the fatigue limits in the S and L directions were 147 and 197 MPa, respectively. The crack population on the surface of a sample at failure increased with the applied stress level and was found to be a Weibull function of the applied maximum stress in this alloy. The strength distribution of fatigue weakest links, where cracks were initiated, was derived from the Weibull function determined by the experimental data. The fatigue weakest-link density was defined as the crack population per unit area at a stress level close to the ultimate tensile stress and can be regarded as a materials property. The density and strength distribution of fatigue weakest links were found to be markedly different between the L and S directions, accounting for the difference in fatigue limit between the directions in this alloy. They were also found to be different between S-L and S-T samples, and between L-T and L-S samples of this alloy, which could not be revealed by the corresponding S-N curves measured. These differences were due to the anisotropy of the microstructures in different directions in this alloy.
Structure of the pygmy dipole resonance in Sn-124
Endres, J.; Savran, D.; Butler, P. A.; Harakeh, M. N.; Harissopulos, S.; Herzberg, R. -D.; Kruecken, R.; Lagoyannis, A.; Litvinova, E.; Pietralla, N.; Ponomarev, V. Yu.; Popescu, L.; Ring, P.; Scheck, M.; Schlueter, F.; Sonnabend, K.; Stoica, V. I.; Zilges, A.; Wortche, Heinrich
2012-01-01
Background: In atomic nuclei, a concentration of electric dipole strength around the particle threshold, commonly denoted as pygmy dipole resonance, may have a significant impact on nuclear structure properties and astrophysical scenarios. A clear identification of these states and the structure of
Spin Resonance Strength Calculations
Courant, E. D.
2009-08-01
In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.
Spin resonance strength calculations
Courant,E.D.
2008-10-06
In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.
Taliat Ola Yusuf
2014-01-01
Full Text Available This paper investigates the influence of blending of metakaolin with silica rich palm oil fuel ash (POFA on the strength distribution of geopolymer mortar. The broadness of strength distribution of quasi-brittle to brittle materials depends strongly on the existence of flaws such as voids, microcracks, and impurities in the material. Blending of materials containing alumina and silica with the objective of improving the performance of geopolymer makes comprehensive characterization necessary. The Weibull distribution is used to study the strength distribution and the reliability of geopolymer mortar specimens prepared from 100% metakaolin, 50% and 70% palm and cured under ambient condition. Mortar prisms and cubes were used to test the materials in flexure and compression, respectively, at 28 days and the results were analyzed using Weibull distribution. In flexure, Weibull modulus increased with POFA replacement, indicating reduced broadness of strength distribution from an increased homogeneity of the material. Modulus, however, decreased with increase in replacement of POFA in the specimens tested under compression. It is concluded that Weibull distribution is suitable for analyses of the blended geopolymer system. While porous microstructure is mainly responsible for flexural failure, heterogeneity of reaction relics is responsible for the compression failure.
Dipole excitations in the semi-magic nucleus sup 5 sup 1 V studied with the (gamma,gamma') reaction
Kaiser, H; Caurier, E; Eberth, J; Enders, J; Fitzler, A; Fransen, C; Herzberg, R D; Käubler, L; Neumann-Cosel, P V; Pietralla, N; Poves, A; Prade, H; Richter, A; Schnare, H; Schwengner, R; Skoda, S; Thomas, H G; Tiesler, H; Weisshaar, D; Wiedenhöver, I
1999-01-01
We report on a nuclear resonance fluorescence experiment on the semi-magic odd-mass fp-shell nucleus sup 5 sup 1 V. The detected dipole strength distribution is discussed on the basis of modern shell-model calculations employing a model space allowing for excitations of protons and neutrons from the 1f sub 7 sub / sub 2 to the (2p sub 1 sub / sub 2 ,2p sub 3 sub / sub 2 ,1f sub 5 sub / sub 2) shells. The calculations indicate that the main body of transitions is of magnetic dipole type, and they are capable of reproducing the observed distribution well. Possible electric dipole and quadrupole contributions are also discussed.
Uppulury, Karthik; Kolomeisky, Anatoly B.
2016-12-01
Molecular transport across channels and pores is critically important for multiple natural and industrial processes. Recent advances in single-molecule techniques have allowed researchers to probe translocation through nanopores with unprecedented spatial and temporal resolution. However, our understanding of the mechanisms of channel-facilitated molecular transport is still not complete. We present a theoretical approach that investigates the role of molecular interactions in the transport through channels. It is based on the discrete-state stochastic analysis that provides a fully analytical description of this complex process. It is found that a spatial distribution of the interactions strongly influences the translocation dynamics. We predict that there is the optimal distribution that leads to the maximal flux through the channel. It is also argued that the channel transport depends on the strength of the molecule-pore interactions, on the shape of interaction potentials and on the relative contributions of entrance and diffusion processes in the system. These observations are discussed using simple physical-chemical arguments.
Evidence for dipole nature of the low-energy $\\gamma$ enhancement in $^{56}$Fe
Larsen, A C; Bracco, A; Camera, F; Eriksen, T K; Görgen, A; Guttormsen, M; Hagen, T W; Leoni, S; Million, B; Nyhus, H T; Renstrøm, T; Rose, S J; Ruud, I E; Siem, S; Tornyi, T; Tveten, G M; Voinov, A V; Wiedeking, M
2013-01-01
The $\\gamma$-ray strength function of $^{56}$Fe has been measured from proton-$\\gamma$ coincidences for excitation energies up to $\\approx 11$ MeV. The low-energy enhancement in the $\\gamma$-ray strength function, which was first discovered in the ($^3$He,$\\alpha\\gamma$)$^{56}$Fe reaction, is confirmed with the ($p,p^\\prime\\gamma$)$^{56}$Fe experiment reported here. Angular distributions of the $\\gamma$ rays give for the first time evidence that the enhancement is dominated by dipole transitions.
Optical force on toroidal nanostructures: toroidal dipole versus renormalized electric dipole
Zhang, Xu-Lin; Lin, Zhifang; Sun, Hong-Bo; Chan, C T
2015-01-01
We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source-representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field-representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.
Properties and significance of the surface dipole mode
Papakonstantinou, P
2014-01-01
A strong isoscalar dipole resonance is known to be excited in a variety of nuclei, including isospin symmetric ones, at approximately 6-7 MeV. A series of theoretical studies and accumulating experimental evidence support an interpretation of the above dipole resonance as an elementary surface vibration. Obviously, such a mode is potentially as interesting as any collective excitation for a variety of reasons. In addition, though, it is found to account for the observed isoscalar segment of pygmy dipole strength. As discussed here, this has important implications for pygmy-strength interpretations and searches for genuine neutron-skin oscillations.
Miyamoto, R.; Kopp, S.E.; /Texas U.; 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.
Bubnov, Igor N.; Falkovych, I. S.; Gridin, A. A.; Stanislavsky, A. A.; Reznik, A. P.
2015-01-01
Advantages of the diamond dipole antenna as an active antenna are presented. Such an antenna is like an inverted bow-tie antenna, but the former has some advantages over the ordinary bow-tie antenna. It is shown that the diamond dipole antenna may be an effective element of a new antenna array for low-frequency radio astronomy as well as a communication antenna.
Dipole-Dipole Interaction and the Directional Motion of Brownian Motors
YU Hui; ZHAO TongJun; JI Qing; SONG YanLi; WANG YongHong; ZHAN Yong
2002-01-01
The electric field of the microtubule is calculated according to its dipole distribution. The conformationalchange of a molecular motor is described by the rotation ofa dipole which interacts with the microtubulc. The mricalsimulation for the particle current shows that this interaction helps to produce a directional motion along the microtubule.And tte average displacement executes step changes that resemble the experimental result for kinesin motors.
A plasmonic dipole optical antenna coupled quantum dot infrared photodetector
Mojaverian, Neda; Gu, Guiru; Lu, Xuejun
2015-12-01
In this paper, we report a full-wavelength plasmonic dipole optical antenna coupled quantum dot infrared photodetector (QDIP). The plasmonic dipole optical antenna can effectively modify the EM wave distribution and convert free-space propagation infrared light to localized surface plasmonic resonance (SPR) within the nanometer (nm) gap region of the full-wavelength dipole antenna. The plasmonic dipole optical antenna coupled QDIP shows incident-angle-dependent photocurrent enhancement. The angular dependence follows the far-field pattern of a full-wavelength dipole antenna. The directivity of the plasmonic dipole optical antenna is measured to be 1.8 dB, which agrees well with the antenna simulation. To our best knowledge, this is the first report of the antenna far-field and directivity measurement. The agreement of the detection pattern and the directivity with antenna theory confirms functions of an optical antenna are similar to that of a RF antenna.
Probing the Universe's Tilt with the Cosmic Infrared Background Dipole
Fixsen, D J
2011-01-01
Conventional interpretation of the observed cosmic microwave background (CMB) dipole is that all of it is produced by local peculiar motions. Alternative explanations requiring part of the dipole to be primordial have received support from measurements of large-scale bulk flows. A test of the two hypothesis is whether other cosmic dipoles produced by collapsed structures later than last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to ~30% by the COBE satellite. Over the 100 to 500 um wavelength range its spectral energy distribution can provide a probe of its alignment with CMB. This is tested with the COBE FIRAS dataset which is available for such a measurement because of its low noise and frequency resolution important for Galaxy subtraction. Although the FIRAS instrument noise is in principle low enough to determine the CIB dipole, the Galactic foreground is sufficiently close spectrally to keep the CIB dipole hidden. A...
Dark forces and atomic electric dipole moments
Gharibnejad, Heman; Derevianko, Andrei
2015-02-01
Postulating the existence of a finite-mass mediator of T,P-odd coupling between atomic electrons and nucleons, we consider its effect on the permanent electric dipole moment (EDM) of diamagnetic atoms. We present both numerical and analytical analysis for such mediator-induced EDMs and compare it with EDM results for the conventional contact interaction. Based on this analysis, we derive limits on coupling strengths and carrier masses from experimental limits on EDM of the 199Hg atom.
Nemeth, Noel
2013-01-01
Models that predict the failure probability of monolithic glass and ceramic components under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" failure models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This report develops a formulation to describe the probability density distribution of the orientation of critical strength-controlling flaws that results from an applied load. This distribution is a function of the multiaxial stress state, the shear sensitivity of the flaws, the Weibull modulus, and the strength anisotropy. Examples are provided showing the predicted response on the unit sphere for various stress states for isotropic and transversely isotropic (anisotropic) materials--including the most probable orientation of critical flaws for offset uniaxial loads with strength anisotropy. The author anticipates that this information could be used to determine anisotropic stiffness degradation or anisotropic damage evolution for individual brittle (or quasi-brittle) composite material constituents within finite element or micromechanics-based software
Experiments with Dipole Antennas
Kraftmakher, Yaakov
2009-01-01
Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a…
Unexpected distribution of ν 1 f7 /2 strength in 49Ca
Crawford, H. L.; Macchiavelli, A. O.; Fallon, P.; Albers, M.; Bader, V. M.; Bazin, D.; Campbell, C. M.; Clark, R. M.; Cromaz, M.; Dilling, J.; Gade, A.; Gallant, A.; Holt, J. D.; Janssens, R. V. F.; Krücken, R.; Langer, C.; Lauritsen, T.; Lee, I. Y.; Menéndez, J.; Noji, S.; Paschalis, S.; Recchia, F.; Rissanen, J.; Schwenk, A.; Scott, M.; Simonis, J.; Stroberg, S. R.; Tostevin, J. A.; Walz, C.; Weisshaar, D.; Wiens, A.; Wimmer, K.; Zhu, S.
2017-06-01
The calcium isotopes have emerged as a critical testing ground for new microscopically derived shell-model interactions, and a great deal of experimental and theoretical focus has been directed toward this region. We investigate the relative spectroscopic strengths associated with 1 f7 /2 neutron hole states in Ca,4947 following one-neutron knockout reactions from Ca,5048. The observed reduction of strength populating the 7 /21- state in 49Ca, as compared to 47Ca, is inconsistent with shell-model calculations using both phenomenological interactions such as GXPF1, and interactions derived from microscopically based two- and three-nucleon forces. The result suggests a fragmentation of the l =3 strength to higher-lying states as suggested by the microscopic calculations, but the observed magnitude of the reduction is not reproduced in any shell-model description.
Electric and Magnetic Dipole States in ^238U
Hammond, S. L.; Adekola, A.; Angell, C. T.; Karwowski, H. J.; Howell, C. R.; Kwan, E.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Kelley, J. H.
2010-11-01
An investigation of dipole states in ^238U is important for the fundamental understanding of its structure. Precise experimental information on the distribution of M1 and E1 transitions in ^238U has been obtained using the nuclear resonance fluorescence technique at the High-Intensity γ-ray Source at the Triangle Universities Nuclear Laboratory. Using 100% linearly-polarized, monoenergetic γ-ray beams between incident energies of 2.0 - 5.5 MeV, the spin, parity, width, and γ-strength of the ground-state deexcitations were determined. These measurements will form a unique data set that can be used for comparison with theoretical models of collective excitations in heavy, deformed nuclei. The data can also provide isotope-specific signatures to search for special nuclear materials.
Collective Dipole-Dipole Interactions in an Atomic Array
Sutherland, R T
2016-01-01
The coherent dipole-dipole interactions of atoms in an atomic array are studied. It is found that the excitation probability of an atom in an array parallel to the direction of laser propagation ($\\boldsymbol{\\hat{k}}$) will either grow or decay logarithmically along $\\boldsymbol{\\hat{k}}$, depending on the detuning of the laser. The symmetry of the system for atomic separations of $\\delta r = j\\lambda/2$, where $j$ is an integer, causes the excitation distribution and scattered radiation to abruptly become symmetric about the center of the array. For atomic separations of $\\delta r < \\lambda/2$, the appearance of a collection of extremely subradiant states ($\\Gamma\\sim 0$), disrupts the described trend. In order to interpret the results from a finite array of atoms, a band structure calculation in the $N\\rightarrow \\infty$ limit is conducted where the decay rates and the Collective Lamb Shifts of the eigenmodes along the Brillouin zone are shown. Finally, the band structure of an array strongly affects it...
Dipole response in neutron-rich nuclei within self-consistent approaches using realistic potentials
Lo Iudice N.
2015-01-01
Full Text Available A nucleon-nucleon chiral potential with a corrective density dependent term simulating a three-body force is used in a self-consistent calculation of the dipole strength distribution in neutron-rich nuclei, with special attention to the low-lying spectra associated to the pygmy resonance. A Hartree-Fock-Bogoliubov basis is generated and adopted in Tamm-Dancoff and random-phase approximations and, then, in an equation of motion approach which includes a basis of two-phonon states. The direct use of the mentioned chiral potential improves the description of both giant and pygmy dipole modes with respect to other realistic interactions. Moreover, the inclusion of the two-phonon states induces a pronounced fragmentation of the giant resonance and enhances the density of the low-lying levels in the pygmy region in agreement with recent experiments.
Interaction between two magnetic dipoles in a uniform magnetic field
J. G. Ku
2016-02-01
Full Text Available A new formula for the interaction force between two magnetic dipoles in a uniform magnetic field is derived taking their mutual magnetic interaction into consideration and used to simulate their relative motion. Results show that when the angle β between the direction of external magnetic field and the centerline of two magnetic dipoles is 0 ° or 90 °, magnetic dipoles approach each other or move away from each other in a straight line, respectively. And the time required for them to contact each other from the initial position is related to the specific susceptibility and the diameter of magnetic particles, medium viscosity and magnetic field strength. When β is between 0 ° and 90 °, magnetic dipole pair performs approximate elliptical motion, and the motion trajectory is affected by the specific susceptibility, diameter and medium viscosity but not magnetic field strength. However, time required for magnetic dipoles to complete the same motion trajectory is shorter when adopting stronger magnetic field. Moreover, the subsequent motion trajectory of magnetic dipoles is ascertained once the initial position is set in a predetermined motion trajectory. Additionally, magnetic potential energy of magnetic dipole pairs is transformed into kinetic energy and friction energy during the motion.
Span-Dependent Distributions of the Bending Strength of Spruce Timber
Ditlevsen, Ove; Källsner, Bo
2005-01-01
Tests data of bending strengths of a large number of timber beams of different spans obtained at the Swedish Institute for Wood Technology Research reveal a statistical structure that can be represented in a simple probabilistic model of series system type. A particular feature of the data from one...
Microstructure and Hardness Distribution of Resistance Welded Advanced High Strength Steels
Pedersen, Kim Richardt; Harthøj, Anders; Friis, Kasper Leth
2008-01-01
In this work a low carbon steel and two high strength steels (DP600 and TRIP700) have been resistance lap welded and the hardness profiles were measured by micro hardness indentation of cross sections of the joint. The resulting microstructure of the weld zone of the DP-DP and TRIP-TRIP joints were...
Microstructure and homogeneity of distribution of mineralised struts determine callus strength
M Mehta
2013-07-01
Full Text Available Non-invasive assessment of fracture healing, both in clinical and animal studies, has gained favour as surrogate measure to estimate regain of mechanical function. Micro-computed tomography (µCT parameters such as fracture callus volume and mineralisation have been used to estimate callus mechanical competence. However, no in-depth information has been reported on microstructural parameters in estimating callus mechanical competence. The goal of this study is to use differently conditioned mice exhibiting good and impaired fracture healing outcomes and investigate the relationship between µCT imaging parameters (volume, mineralisation, and microstructure that best estimate the callus strength and stiffness as it develops over time. A total of 99 mice with femoral fracture and intramedullary stabilisation were divided into four groups according to conditioning: wild type, NF1 knock-out, RAG1 knock-out and macrophage depleted. Animals were sacrificed at 14, 21, 28 or 35 days and µCT parameters and torsional stiffness and strength were assessed post-sacrifice. Using linear regression for all groups and time points together, torsional stiffness could be estimated with strut thickness, strut number and strut homogeneity (R2 = 0.546, p < 0.0001; torsional strength could be estimated using bone mineral density, strut thickness and strut homogeneity (R2 = 0.568, p < 0.0001. Differently conditioned mice that result in different fracture healing outcomes have been shown to result in varying structural, material and volumetric µCT parameters which can be used to estimate regain of bone strength. This study is the first to demonstrate that microstructure and strut homogeneity influence callus stiffness and strength.
Virtanen, H.; Keshvari, J.; Lappalainen, R.
2007-03-01
As the use of radiofrequency (RF) electromagnetic (EM) fields has increased along with increased use of wireless communication, the possible related health risks have also been widely discussed. One safety aspect is the interaction of medical implants and RF devices like mobile phones. In the literature, effects on active implants like pacemakers have been discussed but the studies of passive metallic (i.e. conductive) implants are rare. However, some studies have shown that the EM power absorption in tissues may be enhanced due to metallic implants. In this study, the effect of authentic passive metallic implants in the head region was examined. A half-wave dipole antenna was used as an exposure source and the specific absorption rate (SAR, W kg-1) in the near field was studied numerically. The idea was to model the presumably worst cases of most common implants in an accurate MRI-based phantom. As exposure frequencies GSM (900 and 1800 MHz) and UMTS (2450 MHz) regions were considered. The implants studied were skull plates, fixtures, bone plates and ear rings. The results indicate that some of the implants, under very rare exposure conditions, may cause a notable enhancement in peak mass averaged SAR.
Kolasinski, Joanna; Kaehler, Sven; Jaquemet, Sébastien
2012-08-01
This study investigates eddy induced transport processes that affect the sources and sinks of organic matter in the Mozambique Channel (MC). Eddies generated in the MC interact with the continental shelf and have been hypothesized to act as conveyor belts that entrain coastal production offshore. A combination of natural isotope tracers, elemental composition and physico-chemical variables allowed distinguishing two sources of organic matter within the eddy dipole. Near the surface, coastal POM was entrained at the anti-cyclonic boundary and further transferred into the eddy. Anti-cyclonic surface POM containing coastal POM was downwelled into deeper layers where decomposition greatly affected its composition. In contrast, cyclonic water promoted new production, by upwelling nutrient-rich deep waters into the euphotic zone. This production circulated through the mixed layer of the cyclone and was possibly advected into the boundary. Boundary F(max) and surface waters shared characteristics with the cyclone and anti-cyclone respectively as the result of both import of primary production of cyclonic origin occurring at F(max) and entrainment of coastal biological material at the surface. In the overall low productivity environment of the MC, it is likely that the continuous migration of mesoscale eddies along the shelf plays an important ecological role both in enhancing pelagic production and transporting coastal production offshore.
Dipole response of the odd-proton nucleus ^{205} Tl up to the neutron-separation energy
Benouaret, N.; Beller, J.; Pai, H.; Pietralla, N.; Ponomarev, V. Yu; Romig, C.; Schnorrenberger, L.; Zweidinger, M.; Scheck, M.; Isaak, J.; Savran, D.; Sonnabend, K.; Raut, R.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Kelley, J. H.
2016-10-17
The low-lying electromagnetic dipole strength of the odd-proton nuclide ^{205}Tl has been investigated up to the neutron separation energy exploiting the method of nuclear resonance fluorescence. In total, 61 levels of ^{205}Tl have been identified. The measured strength distribution of ^{205}Tl is discussed and compared to those of even–even and even–odd mass nuclei in the same mass region as well as to calculations that have been performed within the quasi-particle phonon model.
Casas, C.; Tejedor, R. [Department of Materials Science and Metallurgical Engineering, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Rodríguez-baracaldo, R. [Department of Mechanical Engineering, Universidad Nacional de Colombia, Bogotá. Colombia (Colombia); Benito, J.A., E-mail: Josep.a.benito@upc.edu [Department of Materials Science and Metallurgical Engineering, EUETIB, Universitat Politècnica de Catalunya, Comte d' Urgell 187, 08036 Barcelona (Spain); Fundació CTM Centre Tecnològic de Manresa, Plaça de la Ciencia, 2, 08243 Manresa (Spain); Cabrera, J.M. [Department of Materials Science and Metallurgical Engineering, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundació CTM Centre Tecnològic de Manresa, Plaça de la Ciencia, 2, 08243 Manresa (Spain)
2015-03-11
The strength and ductility of bulk nanostructured and ultrafine-grained iron containing 0.39% oxygen by weight was determined by tensile tests. Samples were obtained by consolidation of milled iron powder at 500 °C. Heat treatments were designed to cover a wide range of grain sizes spanning from 100 to 2000 nm with different percentages of coarse and nanostructured grain areas, which was defined as a bimodal grain size distribution. Transmission electron microscopy was used to determine the diameter, volume fraction and location of oxides in the microstructure. The strength was analysed following two approaches. The first one was based on the strong effect of oxides and involved the use of a mixed particle-grain boundary strengthening model, and the second one was based on simple grain boundary strengthening. The mixed model underestimated the strength of nanostructured samples, whereas the simple grain boundary model worked better. However, for specimens with a bimodal grain size, the fitting of the mixed model was better. In this case, the more effective particle strengthening was related to the dispersion of oxides inside the large ferrite grains. In addition, the bimodal samples showed an acceptable combination of strength and ductility. Again, the ferrite grains containing oxides promoted strain hardening due to the increase in dislocation activity.
Probing the Universe's Tilt with the Cosmic Infrared Background Dipole
Fixsen, D. J.; Kashlinsky, A.
2011-06-01
Conventional interpretation of the observed cosmic microwave background (CMB) dipole is that all of it is produced by local peculiar motions. Alternative explanations requiring part of the dipole to be primordial have received support from measurements of large-scale bulk flows. A test of the two hypotheses is whether other cosmic dipoles produced by collapsed structures later than the last scattering coincide with the CMB dipole. One background is the cosmic infrared background (CIB) whose absolute spectrum was measured to ~30% by the COBE satellite. Over the 100-500 μm wavelength range its spectral energy distribution can provide a probe of its alignment with the CMB. This is tested with the COBE FIRAS data set which is available for such a measurement because of its low noise and frequency resolution which are important for Galaxy subtraction. Although the FIRAS instrument noise is in principle low enough to determine the CIB dipole, the Galactic foreground is sufficiently close spectrally to keep the CIB dipole hidden. A similar analysis is performed with DIRBE, which—because of the limited frequency coverage—provides a poorer data set. We discuss strategies for measuring the CIB dipole with future instruments to probe the tilt and apply it to the Planck, Herschel, and the proposed Pixie missions. We demonstrate that a future FIRAS-like instrument with instrument noise a factor of ~10 lower than FIRAS would make a statistically significant measurement of the CIB dipole. We find that the Planck and Herschel data sets will not allow a robust CIB dipole measurement. The Pixie instrument promises a determination of the CIB dipole and its alignment with either the CMB dipole or the dipole galaxy acceleration vector.
2004-01-01
The cold mass of a 15-metre main dipole magnet has some fifteen different components. All the main components are manufactured under CERN's direct responsibility. Four of them transit through CERN before being shipped to the dipole assembly contractors, namely the cable, which constitutes the magnet's superconducting core (see Bulletin 14/2004), the beam screens, the heat exchanger tubes and the cold bore beam tubes. The two latter components transit via Building 927 where they undergo part of the production process. The 58-mm diameter heat exchanger tubes will remove heat from the magnets using superfluid helium. The 53-mm diameter cold bore tubes will be placed under vacuum to allow the twin beams to circulate around the LHC.
Competition between finite-size effects and dipole-dipole interactions in few-atom systems
Damanet, François; Martin, John
2016-11-01
In this paper, we study the competition between finite-size effects (i.e. discernibility of particles) and dipole-dipole interactions in few-atom systems coupled to the electromagnetic field in vacuum. We consider two hallmarks of cooperative effects, superradiance and subradiance, and compute for each the rate of energy radiated by the atoms and the coherence of the atomic state during the time evolution. We adopt a statistical approach in order to extract the typical behaviour of the atomic dynamics and average over random atomic distributions in spherical containers with prescribed {k}0R with k 0 the radiation wavenumber and R the average interatomic distance. Our approach allows us to highlight the tradeoff between finite-size effects and dipole-dipole interactions in superradiance/subradiance. In particular, we show the existence of an optimal value of {k}0R for which the superradiant intensity and coherence pulses are the less affected by dephasing effects induced by dipole-dipole interactions and finite-size effects.
Maximilien Brice
2004-01-01
The ALICE cavern receives a painting made specially to mark the 50th anniversary of CERN that is mounted on the L3 solenoid magnet, reused from the LEP experiment that ran from 1989 to 2000. The dipole, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid. These muons are heavy electrons that interact less with matter allowing them to be studied at large distances from the interaction point.
Giant Primeval Magnetic Dipoles
Thompson, Christopher
2017-07-01
Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.
Nicholls, David C; Sutherland, Ralph S; Kewley, Lisa J; Palay, Ethan
2013-01-01
In this paper we develop tools for observers to use when analysing nebular spectra for temperatures and metallicities, with two goals: to present a new, simple method to calculate equilibrium electron temperatures for collisionally excited line flux ratios, using the latest atomic data; and to adapt current methods to include the effects of possible non-equilibrium '{\\kappa}' electron energy distributions. Adopting recent collision strength data for [O iii], [S iii], [O ii], [S ii], and [N ii], we find that existing methods based on older atomic data seriously overestimate the electron temperatures, even when considering purely Maxwellian statistics. If {\\kappa} distributions exist in H ii regions and planetary nebulae as they do in solar system plasmas, it is important to investigate the observational consequences. This paper continues our previous work on the {\\kappa} distribution (Nicholls et al. 2012). We present simple formulaic methods that allow observers to (a) measure equilibrium electron temperature...
Girwidz, Raimund V.
2016-11-01
The Hertzian dipole is fundamental to the understanding of dipole radiation. It provides basic insights into the genesis of electromagnetic waves and lays the groundwork for an understanding of half-wave antennae and other types. Equations for the electric and magnetic fields of such a dipole can be derived mathematically. However these are very abstract descriptions. Interpreting these equations and understanding travelling electromagnetic waves are highly limited in that sense. Visualizations can be a valuable supplement that vividly present properties of electromagnetic fields and their propagation. The computer simulation presented below provides additional instructive illustrations for university lectures on electrodynamics, broadening the experience well beyond what is possible with abstract equations. This paper refers to a multimedia program for PCs, tablets and smartphones, and introduces and discusses several animated illustrations. Special features of multiple representations and combined illustrations will be used to provide insight into spatial and temporal characteristics of field distributions—which also draw attention to the flow of energy. These visualizations offer additional information, including the relationships between different representations that promote deeper understanding. Finally, some aspects are also illustrated that often remain unclear in lectures.
Holanda, B A; Cordeiro, R C; Blak, A R, E-mail: bruna.holanda@usp.br, E-mail: renan.cordeiro@usp.br, E-mail: anablak@if.usp.br
2010-11-15
Dipole defects in gamma irradiated and thermally treated beryl (Be{sub 3}Al{sub 2}Si{sub 6}O{sub 18}) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.
IMPROVEMENT OF EXPRESSION FOR EXCITATION BY AN ELECTRIC DIPOLE IN GTEM CELL
Ren Liehui; Chen Zhiyu
2002-01-01
On the basis of Wilson's work in which the vertical electric dipole is centrally located in GHz Transverse ElectroMagnetic (GTEM) cell, we deduce the expression for the field distribution excited by an electric dipole in the case that the dipole is not centrally located. It will be useful for EMC measurements using GTEM cell.
IMPROVEMENT OF EXPRESSION FOR EXCITATION BY AN ELECTRIC DIPOLE IN GTEM CELL
RenLiehui; ChenZhiyu
2002-01-01
On the basis of Wilson's work in which the vertical electric dipole is centrally located in GHz Transverse ElectroMagntic(GTEM) cell, we deduce the expression for the field distribution excited by an electric dipole in the case that the dipole is not centrally located.It will be useful for EMCmeasurements using GTEM cell.
Synchronization of magnetic dipole rotation in an ac magnetic field
Belovs, M; Cebers, A, E-mail: aceb@tesla.sal.lv [University of Latvia, Zellu-8, Riga, LV-1002 (Latvia)
2011-07-22
The synchronization of the rotation of magnetic dipoles due to weak dipolar interactions is studied. The set of equations is analyzed by the time averaging technique. It is found that dipoles synchronously oscillate at low applied fields and rotate synchronously at large applied fields. The mean angular velocity of synchronous rotation increases with the field strength and reaches a constant value equal to the angular frequency of the field above the critical value of the field strength. The critical value of the field strength above which the synchronous rotation takes place can be calculated from dimensionless parameters using a model derived from first principles by others. The values thus obtained are in good agreement with the values we obtain from a numerical simulation. Thus, we may conclude that the liquid flow observed in these systems may be caused by synchronized rotations of the dipoles.
Permeability and pore size distribution in medium strength self-compacting concrete
Fernández Cánovas, M.
2010-09-01
Full Text Available The use of self-compacting concrete (SCC has been on the rise in recent years. Research on this type of concrete has focused primarily on determining optimal dosage, while durability, particularly for medium strength SCC, has received much less attention.
The present study explored the permeability of a number of medium strength (characteristic strength, 30 MPa self-compacting concretes, including SCCs made with common cement, in pursuit of a balance between performance and cost. Pressurised water and mercury intrusion porosimetry tests were conducted to determine concrete behaviour when exposed to aggressive agents.
The findings showed that the capillary networks of these concretes are essentially impermeable to aggressive agents.
El hormigón autocompactante ha experimentado un amplio desarrollo en los últimos años. Los estudios sobre este hormigón se han centrado en obtener dosificaciones óptimas, mientras los relativos a su durabilidad son escasos, especialmente en el caso de hormigones de resistencia moderada.
Este trabajo se centra en el estudio de la permeabilidad de distintos hormigones autocompactantes de resistencia moderada (resistencia característica 30 MPa. El estudio incluye hormigones fabricados con cementos comunes, en los que se ha buscado un equilibrio entre prestaciones y precio. Con el fin de estudiar su comportamiento frente a la penetración de agentes agresivos, se han realizado los ensayos de permeabilidad al agua bajo presión y estudio de la porosimetría por intrusión de mercurio.
Los resultados de los ensayos ponen de manifiesto el buen comportamiento de estos hormigones frente a la posible penetración de agentes agresivos por la red capilar.
Nuclear electric dipole moments for the lowest 1/2+ states in Xe and Ba isotopes
Yoshinaga, N.; Higashiyama, K.; Arai, R.; Teruya, E.
2014-04-01
The electric dipole moments for the lowest 1/2+ states of Xe and Ba isotopes are calculated in terms of the nuclear shell model, which includes two-body nucleon interactions violating parity and time-reversal invariance. Using the wave functions thus obtained, the nuclear electric dipole moments arising from the intrinsic nucleon electric dipole moments and also from asymmetric charge distribution are calculated. The upper limits for the nuclear electric dipole moments of Xe and Ba isotopes are estimated.
Photoelectron spectroscopy and the dipole approximation
Hemmers, O.; Hansen, D.L.; Wang, H. [Univ. of Nevada, Las Vegas, NV (United States)] [and others
1997-04-01
Photoelectron spectroscopy is a powerful technique because it directly probes, via the measurement of photoelectron kinetic energies, orbital and band structure in valence and core levels in a wide variety of samples. The technique becomes even more powerful when it is performed in an angle-resolved mode, where photoelectrons are distinguished not only by their kinetic energy, but by their direction of emission as well. Determining the probability of electron ejection as a function of angle probes the different quantum-mechanical channels available to a photoemission process, because it is sensitive to phase differences among the channels. As a result, angle-resolved photoemission has been used successfully for many years to provide stringent tests of the understanding of basic physical processes underlying gas-phase and solid-state interactions with radiation. One mainstay in the application of angle-resolved photoelectron spectroscopy is the well-known electric-dipole approximation for photon interactions. In this simplification, all higher-order terms, such as those due to electric-quadrupole and magnetic-dipole interactions, are neglected. As the photon energy increases, however, effects beyond the dipole approximation become important. To best determine the range of validity of the dipole approximation, photoemission measurements on a simple atomic system, neon, where extra-atomic effects cannot play a role, were performed at BL 8.0. The measurements show that deviations from {open_quotes}dipole{close_quotes} expectations in angle-resolved valence photoemission are observable for photon energies down to at least 0.25 keV, and are quite significant at energies around 1 keV. From these results, it is clear that non-dipole angular-distribution effects may need to be considered in any application of angle-resolved photoelectron spectroscopy that uses x-ray photons of energies as low as a few hundred eV.
Quantum emitter dipole-dipole interactions in nanoplasmonic systems
Nečada, Marek; Törmä, Päivi
2016-01-01
We introduce a generalized Dicke-like model to describe two-level systems coupled with a single bosonic mode. In addition, the two-level systems mutually interact via direct dipole-dipole interaction. We apply the model to an ensemble of dye molecules coupled to a plasmonic excitation in a metallic nanoparticle and study how the dipole-dipole interaction and configurational randomness introduced to the system affect the energy spectra. Comparing the system eigenenergies obtained by our model with the light spectra from a multiple-scattering simulation, we suggest a way to identify dark modes in our model. Finally, we perform a parameter sweep in order to determine the scaling properties of the system and to classify the regions of the parameter space where the dipole-dipole interactions can have significant effects.
Microstructure and Hardness Distribution of Resistance Welded Advanced High Strength Steels
Pedersen, Kim Richardt; Harthøj, Anders; Friis, Kasper Leth
2008-01-01
simulated numerically and together with the material carbon equivalent, austenization temperatures and the thermal history the simulations were used to estimate the resulting post weld hardness using the commercial FE code SORPAS. The hardness of the welds of dissimilar materials was estimated......In this work a low carbon steel and two high strength steels (DP600 and TRIP700) have been resistance lap welded and the hardness profiles were measured by micro hardness indentation of cross sections of the joint. The resulting microstructure of the weld zone of the DP-DP and TRIP-TRIP joints were...... found to consist of a martensitic structure with a significant increase in hardness. Joints of dissimilar materials mixed completely in the melted region forming a new alloy with a hardness profile lying in between the hardness measured in joints of the similar materials. Furthermore the joints were...
Retardation effects in induced atomic dipole-dipole interactions
Graham, S D
2016-01-01
We present mean-field calculations of azimuthally averaged retarded dipole-dipole interactions in a Bose-Einstein condensate induced by a laser, at both long and short wavelengths. Our calculations demonstrate that dipole-dipole interactions become significantly stronger at shorter wavelengths, by as much as 30-fold, due to retardation effects. This enhancement, along with inclusion of the dynamic polarizability, indicate a method of inducing long-range interatomic interactions in neutral atom condensates at significantly lower intensities than previously realized.
Superconducting dipole electromagnet
Purcell, John R.
1977-07-26
A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.
Rossi, Dominic M.
2010-01-25
The electric dipole response of neutron-rich nickel isotopes has been investigated using the LAND setup at GSI in Darmstadt (Germany). Relativistic secondary beams of {sup 56-57}Ni and {sup 67-72}Ni at approximately 500 AMeV have been generated using projectile fragmentation of stable ions on a 4 g/cm{sup 2} Be target and subsequent separation in the magnetic dipole fields of the FRagment Separator (FRS). After reaching the LAND setup in Cave C, the radioactive ions were excited electromagnetically in the electric field of a Pb target. The decay products have been measured in inverse kinematics using various detectors. Neutron-rich {sup 67-69}Ni isotopes decay by the emission of neutrons, which are detected in the LAND detector. The present analysis concentrates on the ({gamma},n) and ({gamma},2n) channels in these nuclei, since the proton and three-neutron thresholds are unlikely to be reached considering the virtual photon spectrum for nickel ions at 500 AMeV. A measurement of the stable {sup 58}Ni isotope is used as a benchmark to check the accuracy of the present results with previously published data. The measured ({gamma},n) and ({gamma},np) channels are compared with an inclusive photoneutron measurement by Fultz and coworkers, which are consistent within the respective errors. The measured excitation energy distributions of {sup 67-69}Ni contain a large portion of the Giant Dipole Resonance (GDR) strength predicted by the Thomas-Reiche-Kuhn energy-weighted sum rule, as well as a significant amount of low-lying E1 strength, that cannot be attributed to the GDR alone. The GDR distribution parameters are calculated using well-established semi-empirical systematic models, providing the peak energies and widths. The GDR strength is extracted from the {chi}{sup 2} minimization of the model GDR to the measured data of the ({gamma},2n) channel, thereby excluding any influence of eventual low-lying strength. The subtraction of the obtained GDR distribution from the
A E Kotp
2011-04-01
The study of thermally stimulated depolarization current (TSDC) using the dipole–dipole interaction model is described in this work. The dipole–dipole interactionmodel (DDIM) determines the TSDC peak successfully since it gives significant peak parameters (i.e. activation energy () and pre-exponential factor ($\\tau_{0}$)) in addition to the dipole–dipole interaction strength parameter ($d_{i}$). Application of this model to study the peak parameters of some polymeric systems is presented.
Comparative cephalopod shell strength and the role of septum morphology on stress distribution
Robert Lemanis
2016-09-01
suggest that the ratio used to characterize septal morphology in the septal strength index and in calculations of tensile strength of nacre are likely insufficient. A better understanding of the material properties of cephalopod nacre may allow the estimation of maximum depth limits of shelled cephalopods through finite element analysis.
Comparative cephalopod shell strength and the role of septum morphology on stress distribution.
Lemanis, Robert; Zachow, Stefan; Hoffmann, René
2016-01-01
used to characterize septal morphology in the septal strength index and in calculations of tensile strength of nacre are likely insufficient. A better understanding of the material properties of cephalopod nacre may allow the estimation of maximum depth limits of shelled cephalopods through finite element analysis.
Sedimentation equilibrium of magnetic nanoparticles with strong dipole-dipole interactions
Kuznetsov, Andrey A.; Pshenichnikov, Alexander F.
2017-03-01
Langevin dynamics simulation is used to study the suspension of interacting magnetic nanoparticles (dipolar spheres) in a zero applied magnetic field and in the presence of a gravitational (centrifugal) field. A particular emphasis is placed on the equilibrium vertical distribution of particles in the infinite horizontal slab. An increase in the dipolar coupling constant λ (the ratio of dipole-dipole interaction energy to thermal energy) from zero to seven units causes an increase in the particle segregation coefficient by several orders of magnitude. The effect of anisotropic dipole-dipole interactions on the concentration profile of particles is the same as that of the isotropic van der Waals attraction modeled by the Lennard-Jones potential. In both cases, the area with a high-density gradient separating the area with high and low particle concentration is formed on the profiles. Qualitative difference between two potentials manifests itself only in the fact that in the absence of a gravitational field the dipole-dipole interactions do not lead to the "gas-liquid" phase transition: no separation of the system into weakly and highly concentrated phases is observed. At high particle concentration and at large values of λ , the orientational ordering of magnetic dipoles takes place in the system. Magnetic structure of the system strongly depends on the imposed boundary conditions. Spontaneous magnetization occurs in the infinite horizontal slab (i.e., in the rectangular cell with two-dimensional periodic boundary conditions). Replacement of the infinite slab by the finite-size hard-wall vertical cylinder leads to the formation of azimuthal (vortex-like) order. The critical values of the coupling constant corresponding to the transition into an ordered state are very close for two geometries.
Reorientation of Defect Dipoles in Ferroelectric Ceramics
LI Bao-Shan; LI Guo-Rong; ZHAO Su-Chuan; ZHU Zhi-Gang; DING Ai-Li
2005-01-01
@@ We investigate the frequency, temperature, tetragonality and quenched temperature dependences of the hysteresis loops in Pb[(Zr0.52 Ti0.48)0.95 (Mn1/3Nb2/3)0.05]O3 (PMnN-PZT) ceramics. It has been demonstrated that the polarization-field hysteresis curves show "pinched" shapes when tested at room temperature, higher frequency or using the large-tetragonality specimen. While normal square-like loops are observed at 200 ℃ and 0.01 Hz or using the small-tetragonality one. Meanwhile, close relations between the P-E loops and the applied frequency,temperature or tetragonality reveal that there exists a typical relaxation time corresponding to the reorientation of the defect dipoles. It can be seen further from the quenched temperature dependences of the loops that the reorientation of the defect dipoles may influence the pinching. Compared to the intrinsic depinning procedure induced by changes of the distribution of defect dipoles, we provide new evidence for extrinsic depinning mechanism of the defect dipoles in the ferroelectric ceramics.
Zeroes in continuum - continuum dipole matrix elements
Obolensky, Oleg I.; Pratt, R. H.; Korol, Andrei
2003-05-01
It is well known that Cooper minima in photoeffect cross sections are due to zeroes in corresponding bound-free dipole matrix elements. As was discussed before(C. D. Shaffer, R. H. Pratt, and S. D. Oh, Phys. Rev. A. 57), 227 (1998)., free-free dipole matrix elements in screened (atomic or ionic) potentials can also have zeroes. Such zeroes (existing at energies of the order of 1-100 eV) result in structures in the energy dependence of bremsstrahlung cross sections and angular distributions(A. Florescu, O. I. Obolensky, C. D. Shaffer, and R. H. Pratt, AIP Conference Proceedings, 576), 60 (2001).. In the soft photon limit, zeroes of radiative free-free matrix elements are related to Ramsauer-Townsend minima in elastic scattering of electrons by atoms. Here we study properties of the trajectories of dipole matrix element zeroes in the plane of initial and final electron energies. We show how the trajectories in this plane evolve with ionicity for several low ℓ dipole transitions ℓ → ℓ ± 1.
Veronika Gergócs
2010-12-01
Full Text Available Several methods and indicators can be used to evaluate the coenological state of a given habitat, the ones which can be created simply, quickly, standardizably and reliably and which can be used to exactly quantify the state of a given habitat in point of numbers can be of outstanding practical importance in ecology. One possible method is the examination of the genera which can be found in a given habitat in great abundance and have little number of species and various ecological characteristics. For this purpose one of the most appropriate groups is that of ground-dwelling oribatid mites (Acari: Oribatida.In our research, joining the bioindication methodological project of the “Adaptation to Climate Change” Research Group of the Hungarian Academy of Sciences, the indication strength of genus-level taxon lists and the effects of the main pattern-generating factors creating similarity patterns were analysed with the help of data series on oribatid mites collected by us and originating from literature. Our aim was to develop a method with the help of which the difference expressed with distance functions between two oribatid mite genus lists originating from any sources can correspond to spatial and temporal scales. Our results prove that these genus lists are able to express the spatial distance of the habitats. With the help of this base of comparison changes in disturbed or transformed habitats can be expressed by means of oribatid mite communities, with spatial and temporal distances.
Distributed, signal strength-based indoor localization algorithm for use in healthcare environments.
Wyffels, Jeroen; De Brabanter, Jos; Crombez, Pieter; Verhoeve, Piet; Nauwelaers, Bart; De Strycker, Lieven
2014-11-01
In current healthcare environments, a trend toward mobile and personalized interactions between people and nurse call systems is strongly noticeable. Therefore, it should be possible to locate patients at all times and in all places throughout the care facility. This paper aims at describing a method by which a mobile node can locate itself indoors, based on signal strength measurements and a minimal amount of yes/no decisions. The algorithm has been developed specifically for use in a healthcare environment. With extensive testing and statistical support, we prove that our algorithm can be used in a healthcare setting with an envisioned level of localization accuracy up to room revel (or region level in a corridor), while avoiding heavy investments since the hardware of an existing nurse call network can be reused. The approach opted for leads to very high scalability, since thousands of mobile nodes can locate themselves. Network timing issues and localization update delays are avoided, which ensures that a patient can receive the needed care in a time and resources efficient way.
Egorova, Irina A
2016-01-01
New results for electric dipole strength in the chain of even-even Calcium isotopes with the mass numbers A = 40 - 54 are presented. Starting from the covariant Lagrangian of Quantum Hadrodynamics, spectra of collective vibrations (phonons) and phonon-nucleon coupling vertices for $J \\leq 6$ and normal parity were computed in a self-consistent relativistic quasiparticle random phase approximation (RQRPA). These vibrations coupled to Bogoliubov two-quasiparticle configurations (2q$\\otimes$phonon) form the model space for the calculations of the dipole response function in the relativistic quasiparticle time blocking approximation (RQTBA). The results for giant dipole resonance in the latter approach are compared to those obtained in RQRPA and to available data. Evolution of the dipole strength with neutron number is investigated for both high-frequency giant dipole resonance (GDR) and low-lying strength. Development of a pygmy resonant structure on the low-energy shoulder of GDR is traced and analyzed in terms...
Phenomenology on the QCD dipole picture revisited
Lengyel, A I
2003-01-01
We perform an adjust to the most recent structure function data, considering the QCD dipole picture applied to ep scattering. The structure function F2 at small x and intermediate Q2 can be described by the model containing an economical number of free-parameters, which encodes the hard Pomeron physics. The longitudinal structure function and the gluon distribution are predicted without further adjustments. The data description is effective, whereas a resummed next-to-leading level analysis is deserved.
Magnetic dipole moment of a moving electric dipole
Hnizdo, V.
2012-01-01
The current density of a moving electric dipole is expressed as the sum of polarization and magnetization currents. The magnetic field due to the latter current is that of a magnetic dipole moment that is consistent with the relativistic transformations of the polarization and magnetization of macroscopic electrodynamics.
Floriberto Díaz-Díaz
2013-11-01
Full Text Available In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials. The sensor consists of two NdFeB magnets having their North and South poles facing each other, separated by 7 mm to allow space for a Faraday cage containing a Teflon tube and an ellipsoidal RF coil. To account for magnetic field changes due to temperature variations, and/or the presence of steel rebars, or frequency variation due to sample impedance, an external tuning circuit was employed. The sensor performance was evaluated by analyzing the transverse magnetization decay obtained with a CPMG measurement from different materials, such as a polymer phantom, fresh white and grey cement pastes with different w/c ratios and concrete with low (0.30 and high (0.6 w/c ratios. The results indicated that the sensor is capable of detecting changes in water content in fresh cement pastes and porosity refinement caused by cement hydration in hardened materials, even if they are prepared with a low w/c ratio (w/c = 0.30. The short lifetime component of the transverse relaxation rate is directly proportional to the compressive strength of concrete determined by destructive testing. The r2 (0.97 from the linear relationship observed is similar to that obtained using T2 data from a commercial Oxford Instruments 12.9 MHz spectrometer.
Splitting of the Dipole and Spin Dipole Resonances in Pb
Austin, Sam M.
2000-10-01
The response to different neutrino flavors of a supernova neutrino detector based on Pb depends on the position of the spin-dipole resonance(Fuller, Fowler and McLaughlin, Phys. Rev. D59,085005(1999)). In this talk I will present a phenomenolgical model that allows one to extract the splitting of the dipole and spin-dipole resonances from the variation with bombarding energy of the L=1 resonance in (p,n) reactions. This model has been applied previously to the Zr isotopes (Sam M. Austin, Phys. Rev. C, submitted). The dipole splitting for ^208Pb is determined from available data on the (p,n) reaction for bombarding energies between 45 to 200 MeV. It is found to be 4.7±2.0 MeV, with the spin-dipole resonance lying at lower excitation energy.
QCD dipole model and $k_{T}$ factorization
Bialas, A; Peschanski, R
2001-01-01
It is shown that the colour dipole approach to hard scattering at high energy is fully compatible with k_T factorization at the leading logarithm approximation (in -log x_Bj). The relations between the dipole amplitudes and unintegrated diagonal and non-diagonal gluon distributions are given. It is also shown that including the exact gluon kinematics in the k_T factorization formula destroys the conservation of transverse position vectors and thus is incompatible with the dipole model for both elastic and diffractive amplitudes.
Dipole response of neutron-rich Sn isotopes
Klimkiewicz, A.; Adrich, P.; Boretzky, K.; Fallot, M.; Aumann, T.; Cortina-Gil, D.; Datta Pramanik, U.; Elze, Th. W.; Emling, H.; Geissel, H.; Hellstroem, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Leifels, Y.; Nociforo, C.; Palit, R.; Simon, H.; Surowka, G.; Sümmerer, K.; Typel, S.; Walus, W.
2007-05-01
The neutron-rich isotopes 129-133Sn were studied in a Coulomb excitation experiment at about 500 AMeV using the FRS-LAND setup at GSI. From the exclusive measurement of all projectile-like particles following the excitation and decay of the projectile in a high-Z target, the energy differential cross section can be extracted. At these beam energies dipole transitions are dominating, and within the semi-classical approach the Coulomb excitation cross sections can be transformed into photoabsorption cross sections. In contrast to stable Sn nuclei, a substantial fraction of dipole strength is observed at energies below the giant dipole resonance (GDR). For 130Sn and 132Sn this strength is located in a peak-like structure around 10 MeV excitation energy and exhibits a few percent of the Thomas-Reiche Kuhn (TRK) sum-rule strength. Several calculations predict the appearance of dipole strength at low excitation energies in neutron-rich nuclei. This low-lying strength is often referred to as pygmy dipole resonance (PDR) and, in a macroscopic picture, is discussed in terms of a collective oscillation of excess neutrons versus the core nucleons. Moreover, a sharp rise is observed at the neutron separation threshold around 5 MeV for the odd isotopes. A possible contribution of 'threshold strength', which can be described within the direct-breakup model is discussed. The results for the neutron-rich Sn isotopes are confronted with results on stable nuclei investigated in experiments using real photons.
Magnetic field strength and spectral distribution of six parsec-scale active galactic nuclei jets
O'Sullivan, Shane P
2009-01-01
We use observations of six "blazars" with the Very Long Baseline Array (VLBA), at eight frequencies (4.6, 5.1, 7.9, 8.9, 12.9, 15.4, 22.2, 43.1 GHz), to investigate the frequency-dependent position of their VLBI cores ("core-shift") and their overall jet spectral distribution. By cross-correlating the optically thin jet emission, we are able to accurately align the multi-frequency images of three of the jets (1418+546, 2007+777, 2200+420), whose core-shifts and spectra we find consistent with the equipartition regime of the Blandford & Konigl conical jet model, where the position of the radio core from the base of the jet follows $r_{core}\\propto\
Backfire antennas with dipole elements
Nielsen, Erik Dragø; Pontoppidan, Knud
1970-01-01
A method is set up for a theoretical investigation of arbitrary backfire antennas based upon dipole structures. The mutual impedance between the dipole elements of the antenna is taken into account, and the field radiated due to a surface wave reflector of finite extent is determined by calculating...
Resonances and dipole moments in dielectric, magnetic, and magnetodielectric cylinders
Dirksen, A.; Arslanagic, Samel; Breinbjerg, Olav
2011-01-01
An eigenfunction solution to the problem of plane wave scattering by dielectric, magnetic, and magnetodielectric cylinders is used for a systematic investigation of their resonances. An overview of the resonances with electric and magnetic dipole moments, needed in, e.g., the synthesis...... of metamaterials, is given with an emphasis on their strength, bandwidth, and isolation....
KOU Shicong; C S Poon
2006-01-01
The effects of fly ash on the compressive strength, pore size distribution ard chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mixtures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/m3 , respectively. The concrete mixtures in series Ⅱ had a water-to-binder ratio and a cement content of 0.45 and 400 kg/m3 respectively. Recycled aggregate was used as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In addition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased as the recycled aggregate content increased. Furthermore, an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ash improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.
The soliton properties of dipole domains in superlattices
张启义; 田强
2002-01-01
The formation and propagation of dipole domains in superlattices are studied both by the modified discrete driftmodel and by the nonlinear Schrodinger equation. The spatiotemporal distribution of the electric field and electrondensity are presented. The numerical results are compared with the soliton solutions of the nonlinear Schrodingerequation and analysed. It is shown that the numerical solutions agree with the soliton solutions of the nonlinearSchrodinger equation. The dipole electric-field domains in semiconductor superlattices have the properties of solitons.
Dipole—Dipole Interaction and the Directional Motion of Brownian
YUHui; ZHAOTong－Jun; 等
2002-01-01
The electric field of the microtubule is calculated according to its dipole distribution.The conformational change of a molecular motor is described by the rotation of a dipole which interacts with the microtubule.The numerical simulation for the particle currend shows that this interaction helps to produce a directional motion along the microtubule.And the average displacement executes step changes that resemble the experimental result for kinesin motors.
Measurement of the Weak Dipole Moments of the $\\tau$ Lepton
Acciarri, M; Aguilar-Benítez, M; Ahlen, S P; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Baksay, L; Ball, R C; Banerjee, S; Banerjee, Sw; Banicz, K; Barczyk, A; Barillère, R; Barone, L; Bartalini, P; Baschirotto, A; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Bilei, G M; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böck, R K; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Boutigny, D; Braccini, S; Branson, J G; Brigljevic, V; Brock, I C; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Busenitz, J K; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chekanov, S V; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chen, M; Chiefari, G; Chien, C Y; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Cohn, H O; Coignet, G; Colijn, A P; Colino, N; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Dai, T S; D'Alessandro, R; De Asmundis, R; Degré, A; Deiters, K; Denes, P; De Notaristefani, F; DiBitonto, Daryl; Diemoz, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Drago, E; Duchesneau, D; Duinker, P; Durán, I; Dutta, S; Easo, S; Efremenko, Yu V; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ernenwein, J P; Extermann, Pierre; Fabre, M; Faccini, R; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Fenyi, B; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Fredj, L; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gau, S S; Gentile, S; Gerald, J; Gheordanescu, N; Giagu, S; Goldfarb, S; Goldstein, J; Gong, Z F; Gougas, Andreas; Gratta, Giorgio; Grünewald, M W; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hartmann, B; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Van Hoek, W C; Hofer, H; Hoorani, H; Hou, S R; Hu, G; Innocente, Vincenzo; Jenkes, K; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Kasser, A; Khan, R A; Kamrad, D; Kamyshkov, Yu A; Kapustinsky, J S; Karyotakis, Yu; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, D H; Kim, J K; Kim, S C; Kinnison, W W; Kirkby, A; Kirkby, D; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopp, A; Korolko, I; Koutsenko, V F; Krämer, R W; Krenz, W; Kunin, A; Lacentre, P E; Ladrón de Guevara, P; Landi, G; Lapoint, C; Lassila-Perini, K M; Laurikainen, P; Lavorato, A; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Leggett, C; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lu, W; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Majumder, G; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mangla, S; Marchesini, P A; Marin, A; Martin, J P; Marzano, F; Massaro, G G G; McNally, D; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mi, Y; Migani, D; Mihul, A; Van Mil, A J W; Milcent, H; Mirabelli, G; Mnich, J; Molnár, P; Monteleoni, B; Moore, R; Moulik, T; Mount, R; Muheim, F; Muijs, A J M; Nahn, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nippe, A; Nisati, A; Oh, Yu D; Opitz, H; Organtini, G; Ostonen, R; Palit, S; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Park, H K; Park, I H; Pascale, G; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Peach, D; Pei, Y J; Pensotti, S; Perret-Gallix, D; Petersen, B; Petrak, S; Pevsner, A; Piccolo, D; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Produit, N; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Raja, N; Rancoita, P G; Rattaggi, M; Raven, G; Razis, P A; Read, K; Ren, D; Rescigno, M; Reucroft, S; Van Rhee, T; Riemann, S; Riles, K; Rind, O; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosier-Lees, S; Rosselet, P; Van Rossum, W; Roth, S; Rubio, Juan Antonio; Ruschmeier, D; Rykaczewski, H; Salicio, J; Sánchez, E; Sanders, M P; Sarakinos, M E; Sarkar, S; Sauvage, G; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schneegans, M; Scholz, N; Schopper, Herwig Franz; Schotanus, D J; Schwenke, J; Schwering, G; Sciacca, C; Sciarrino, D; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shukla, J; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Soulimov, V; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, H; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Susinno, G F; Suter, H; Swain, J D; Tang, X W; Tauscher, Ludwig; Taylor, L; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tuchscherer, H; Tung, K L; Uchida, Y; Ulbricht, J; Uwer, U; Valente, E; Vesztergombi, G; Vetlitskii, I; Viertel, Gert M; Vivargent, M; Vlachos, S; Völkert, R; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, J C; Wang, X L; Wang, Z M; Weber, A; Wu, S X; Wynhoff, S; Xu, J; Xu, Z Z; Yang, B Z; Yang, C G; Yao, X Y; Ye, J B; Yeh, S C; You, J M; Zalite, A; Zalite, Yu; Zemp, P; Zeng, Y; Zhang, Z; Zhang, Z P; Zhou, B; Zhou, Y; Zhu, G Y; Zhu, R Y; Zichichi, Antonino; Ziegler, F
1998-01-01
Using the data collected by the L3 experiment at LEP from 1991 to 1995 at energies around the $\\Zo$ mass, a measurement of the weak anomalous magnetic dipole moment, $a^w_{\\tau}$,~ and of the weak electric dipole moment, $d^w_{\\tau}$, of the $\\tau$ lepton is performed. These quantities are obtained from angular distributions in $e^{+}e^{-}\\rightarrow\\tau^{+}\\tau^{-} \\rightarrow h^{+} \\bar{\
Nabi, Jameel-Un; Fayaz, Muhammad
2016-01-01
Gamow-Teller transitions in isotopes of chromium play a consequential role in the presupernova evolution of massive stars. $\\beta$-decay and electron capture rates on chromium isotopes significantly affect the time rate of change of lepton fraction ($\\dot{Y_{e}}$). Fine-tuning of this parameter is one of the key for simulating a successful supernova explosion. The (anti)neutrinos produced as a result of electron capture and $\\beta$-decay are transparent to stellar matter during presupernova phases. They carry away energy and this result in cooling the stellar core. In this paper we present the calculations of Gamow-Teller strength distributions and (anti)neutrino energy loss rates due to weak interactions on chromium isotopes of astrophysical importance. We compare our results with measured data and previous calculations wherever available.
Kaiser, H; Caurier, E; Eberth, J; Enders, J; Fitzler, A; Fransen, C; Herzberg, R D; Käubler, L; Von Neumann-Cosel, P; Pietralla, N; Poves, A; Prade, H; Richter, A; Schnare, H; Schwengner, R; Skoda, S; Thomas, H G; Tiesler, H; Weisshaar, D; Wiedenhöver, I
2000-01-01
We report on a nuclear resonance fluorescence experiment on the semi-magic odd-mass fp-shell nucleus sup 5 sup 1 V. The detected dipole strength distribution is discussed on the basis of modern shell-model calculations employing a model space allowing for excitations of protons and neutrons from the 1f sub 7 sub / sub 2 to the (2p sub 1 sub / sub 2 ,2p sub 3 sub / sub 2 ,1f sub 5 sub / sub 2) shells. The calculations indicate that the main body of transitions is of magnetic dipole type, and they are capable of reproducing the observed distribution well. Possible electric dipole and quadrupole contributions are also discussed.
ZHENG Guoxia; SONG Jinming; DAI Jicui; WANG Yiming
2006-01-01
Chlorophyll a (Chl a) concentration and primary productivity (PP), namely, carbon fixed strength of phytoplankton along four transects in the southern Huanghai Sea (SHS) were studied for their distribution features and controlling mechanisms based on the investigations from 17 October to 3 November 2005. The Chl a concentration in the study waters dynamically changed spatially.Surface Chl a concentrations ranged from 0.11 to 2.38 mg/m3 with higher and lower values observed in the nutrient-laden inshore waters and central part of the SHS occupied by oligotrophic current, respectively. The vertical distribution of Chl a concentration showed a predominant pattern of subsurface concentration maximum profile. It followed the previous result of the deep dissolved oxygen concentration maximum profile, which was significantly correlated with phytoplankton and regional water mass. The primapecially phosphate concentration in seawater and hydrological condition. Furthermore, associating the present study results together with previous studies, the annual value of carbon fixed production of phytoplankton in the entire marginal seas of East China(including the Bohai Sea, the Huanghai Sea and the East China Sea) was estimated to be 222 Mt, which accounted for 2% of that in the global margins. Besides, it was as 16.2 times as the annual value of apparent carbon sink strength ( 13.96 Mt) in the marginal seas of East China. This multiple was different in different sea areas (3.0 in the Bohai Sea, 6.7 in the Huanghai Sea and 81.6 in the East China Sea).
Magnetic Field of a Dipole and the Dipole-Dipole Interaction
Kraftmakher, Yaakov
2007-01-01
With a data-acquisition system and sensors commercially available, it is easy to determine magnetic fields produced by permanent magnets and to study the dipole-dipole interaction for different separations and angular positions of the magnets. For sufficiently large distances, the results confirm the 1/R[superscript 3] law for the magnetic field…
Projected Dipole Model for Quantum Plasmonics
Yan, Wei; Wubs, Martijn; Mortensen, N. Asger
2015-01-01
Quantum effects of plasmonic phenomena have been explored through ab initio studies, but only for exceedingly small metallic nanostructures, leaving most experimentally relevant structures too large to handle. We propose instead an effective description with the computationally appealing features...... of classical electrodynamics, while quantum properties are described accurately through an infinitely thin layer of dipoles oriented normally to the metal surface. The nonlocal polarizability of the dipole layer-the only introduced parameter-is mapped from the free-electron distribution near the metal surface...... as obtained with 1D quantum calculations, such as time-dependent density-functional theory (TDDFT), and is determined once and for all. The model can be applied in two and three dimensions to any system size that is tractable within classical electrodynamics, while capturing quantum plasmonic aspects...
Observation of St\\"uckelberg oscillations in dipole-dipole interactions
van Ditzhuijzen, C S E; Heuvell, H B van Linden van den
2009-01-01
We have observed Stueckelberg oscillations in the dipole-dipole interaction between Rydberg atoms with an externally applied radio-frequency field. This proves coherent interaction during at least 0.6 $\\mu$s. The oscillating RF field brings the interaction between cold Rydberg atoms in two separated volumes in resonance and we observe multi-photon transitions when varying the amplitude of the RF-field and the static field offset. The angular momentum states we use show a quadratic Stark shift, which leads to an essentially 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. Both functions are further studied in the classical limit. The oscillatory behavior of both functions correspond to Stueckelberg oscillations, an interferenc...
Dipole-Dipole Interactions of Charged Magnetic Grains
Perry, Jonathan; Hyde, Truell
2010-01-01
The interaction between dust grains is an important process in fields as diverse as planetesimal formation or the plasma processing of silicon wafers into computer chips. This interaction depends in large part on the material properties of the grains, for example whether the grains are conducting, non-conducting, ferrous or non-ferrous. This work considers the effects that electrostatic and magnetic forces, alone or in combination, can have on the coagulation of dust in various environments. A numerical model is used to simulate the coagulation of charged, charged-magnetic and magnetic dust aggregates formed from ferrous material and the results are compared to each other as well as to those from uncharged, non-magnetic material. The interactions between extended dust aggregates are also examined, specifically looking at how the arrangement of charge over the aggregate surface or the inclusion of magnetic material produces dipole-dipole interactions. It will be shown that these dipole-dipole interactions can ...
2001-01-01
Andrezej Siemko (left), Peter Sievers (centre), and Lucio Rossi (right), have the exciting challenge of preparing and testing 2000 magnets for the LHC. The LHC is going to require a lot of powerful magnets by the time it begins operation in 2006. More specifically, it is going to need 130 special magnets, 400 quadrupoles, and a whopping 1250 dipoles! Preparing and testing these magnets for the conditions they will encounter in the LHC is not an easy task. But evaluation of the most recently received magnet, from the German company Noell, is showing that while the monumental task of receiving and testing nearly 2000 magnets is going to be exhausting, the goals are definitely attainable. At the moment and over the next year, pre-series magnets (the magnets that CERN uses to fine tune performance) are arriving slowly (90 in total will arrive), but by 2003 the rate of series magnet arrival will accelerate to 9 per week, that's over 450 in a single year! And working with these magnets when they arrive is tough. ...
Fractional vortex dipole phase filter
Sharma, Manoj Kumar; Joseph, Joby; Senthilkumaran, Paramasivam
2014-10-01
In spatial filtering experiments, the use of vortex phase filters plays an important role in realizing isotropic edge enhancement. In this paper, we report the use of a vortex dipole phase filter in spatial filtering. A dipole made of fractional vortices is used, and its filtering characteristics are studied. It is observed that the filter performance can be tuned by varying the distance of separation between the vortices of the dipole to achieve better contrast and output noise suppression, and when this distance tends to infinity, the filter performs like a 1-D Hilbert mask. Experimental and simulation results are presented.
Storey, P J
2015-01-01
We present effective collision strengths for electron excitation and de-excitation of the ten forbidden transitions between the five lowest energy levels of the astronomically abundant doubly-ionised oxygen ion, O^{2+}. The raw collision strength data were obtained from an R-matrix intermediate coupling calculation using the Breit-Pauli relativistic approximation published previously by the authors. The effective collision strengths were calculated with kappa-distributed electron energies and are tabulated as a function of the electron temperature and kappa.
Emission properties of an oscillating point dipole from a gold Yagi-Uda nanoantenna array
Lobanov, S V; Dregely, D; Giessen, H; Gippius, N A; Tikhodeev, S G
2011-01-01
We investigate numerically the interaction of an oscillating point dipole with a periodic array of optical Yagi-Uda nanoantennas in the weak coupling limit. A very strong near-field enhancement of the dipole emission by the resonant plasmon mode in the feed element is predicted in this structure. It is shown that the enhancement strength depends strongly on the dipole position, the direction of the dipole moment, and the oscillation frequency. The radiative intensity of the point dipole from appropriate places next to one feed element may exceed the radiative intensity of an equivalent dipole in free-space by a factor of hundred. In spite of only one director used in each nanoantenna of the array, the far-field emission pattern is highly directed. The radiative efficiency (the ratio of the radiative to the full emission) appears to be around 20%.
Fine structure of the pygmy dipole resonance in (136)Xe.
Savran, D; Fritzsche, M; Hasper, J; Lindenberg, K; Müller, S; Ponomarev, V Yu; Sonnabend, K; Zilges, A
2008-06-13
The photoresponse of the semimagic N=82 nucleus (136)Xe was measured up to the neutron separation energy S(n) using the (gamma, gamma') reaction. A concentration of strong dipole excitations is observed well below S(n) showing a fragmented resonancelike structure. Microscopic calculations in the quasiparticle phonon model including complex configurations of up to three phonons agree well with the experimental data in the total integrated strength, in the shape and the fragmentation of the resonance, which allows us to draw conclusions on the damping mechanism of the pygmy dipole resonance.
The dipole moment function and vibrational transition intensities of OH
Nelson, David D., Jr.; Schiffman, Aram; Nesbitt, David J.
1989-05-01
Flash-kinetic IR absorption spectroscopy has been used to determine the relative intensities of nine pairs of rovibrational transitions of OH in the v=1-0 fundamental. These intensities are found to be strongly J-dependent in a way that furnishes detailed data on the shape of the OH dipole moment function, and therefore of the absolute IR transition strengths. The rotationless Einstein A coefficient for the OH fundamental is determined on the basis of the dipole moment function to be 16.7(19) Hz; this is noted to be in substantial disagreement with most other experimental and theoretical results.
Fourier-positivity constraints on QCD dipole models
Bertrand G. Giraud
2016-09-01
Full Text Available Fourier-positivity (F-positivity, i.e. the mathematical property that a function has a positive Fourier transform, can be used as a constraint on the parametrization of QCD dipole-target cross-sections or Wilson line correlators in transverse position space r. They are Bessel transforms of positive transverse momentum dependent gluon distributions. Using mathematical F-positivity constraints on the limit r→0 behavior of the dipole amplitudes, we identify the common origin of the violation of F-positivity for various, however phenomenologically convenient, dipole models. It is due to the behavior r2+ϵ, ϵ>0 softer, even slightly, than color transparency. F-positivity seems thus to conflict with the present dipole formalism when it includes a QCD running coupling constant α(r.
Lienkamp, M. (Technische Hochschule Darmstadt, Fachgebiet Physikalische Metallkunde, Fachbereich Materialwissenschaft (Germany)); Exner, H.E. (Technische Hochschule Darmstadt, Fachgebiet Physikalische Metallkunde, Fachbereich Materialwissenschaft (Germany))
1993-04-01
Present test methods used to determine the strength distribution of high performance fibres are either time consuming or not very reliable. A method is used which enables the derivation of the strength distribution function from one single tensile test. The load/elongation diagram of a bundle of fibres is taken from an elongation-controlled tensile test. From the ratio of the measured load to a fictive load, necessary to obtain an identical elongation in the bundle assuming all fibres are intact, the fraction of broken fibres for each point of the load/elongation diagram is determined. From this the strength distribution function and the Weibull parametes of the fibres can be calculated. Application of this simple, but very effective method, is demonstrated for a schematic example and for three fibre materials (carbon, aramid and ceramic fibres). (orig.)
Static electric dipole polarizability of lithium atoms in Debye plasmas
Ning Li-Na; Qi Yue-Ying
2012-01-01
The static electric dipole polarizabilities of the ground state and n ≤ 3 excited states of a lithium atom embedded in a weekly coupled plasma environment are investigated as a function of the plasma screening radium.The plasma screening of the Coulomb interaction is described by the Debye-Hückel potential and the interaction between the valence electron and the atomic core is described by a model potential.The electron energies and wave functions for both the bound and continuum states are calculated by solving the Schr(o)dinger equation numerically using the symplectic integrator.The oscillator strengths,partial-wave,and total static dipole polarizabilities of the ground state and n ≤ 3 excited states of the lithium atom are calculated.Comparison of present results with thosc of other authors,when available,is made.The results for the 2s ground state demonstrated that the oscillator strengths and the static dipole polarizabilities from np orbitals do not always increase or decrease with the plasma screening effect increasing,unlike that for hydrogen-like ions,especially for 2s→3p transition there is a zero value for both the oscillator strength and the static dipole polarizability for screening length D =10.3106a0,which is associated with the Cooper minima.
Synchronization of interacting quantum dipoles
Zhu, B.; Schachenmayer, J.; Xu, M.; Herrera, F.; Restrepo, J. G.; Holland, M. J.; Rey, A. M.
2015-08-01
Macroscopic ensembles of radiating dipoles are ubiquitous in the physical and natural sciences. In the classical limit the dipoles can be described as damped-driven oscillators, which are able to spontaneously synchronize and collectively lock their phases in the presence of nonlinear coupling. Here we investigate the corresponding phenomenon with arrays of quantized two-level systems coupled via long-range and anisotropic dipolar interactions. Our calculations demonstrate that by incoherently driving dense packed arrays of strongly interacting dipoles, the dipoles can overcome the decoherence induced by quantum fluctuations and inhomogeneous coupling and reach a synchronized steady-state characterized by a macroscopic phase coherence. This steady-state bears much similarity to that observed in classical systems, and yet also exhibits genuine quantum properties such as quantum correlations and quantum phase diffusion (reminiscent of lasing). Our predictions could be relevant for the development of better atomic clocks and a variety of noise tolerant quantum devices.
Quantum optical dipole radiation fields
Stokes, Adam
2016-01-01
We introduce quantum optical dipole radiation fields defined in terms of photon creation and annihilation operators. These fields are identified through their spatial dependence, as the components of the total fields that survive infinitely far from the dipole source. We use these radiation fields to perturbatively evaluate the electromagnetic radiated energy-flux of the excited dipole. Our results indicate that the standard interpretation of a bare atom surrounded by a localised virtual photon cloud, is difficult to sustain, because the radiated energy-flux surviving infinitely far from the source contains virtual contributions. It follows that there is a clear distinction to be made between a radiative photon defined in terms of the radiation fields, and a real photon, whose identification depends on whether or not a given process conserves the free energy. This free energy is represented by the difference between the total dipole-field Hamiltonian and its interaction component.
The dipole moment of a wall-charged void in a bulk dielectric
McAllister, Iain Wilson
1993-01-01
The dipole moment of a wall-charged void is examined with reference to the spatial extent of the surface charge density σ and the distribution of this charge. The salient factors influencing the void dipole moment are also examined. From a study of spherical voids, it is shown that, although the σ......-distribution influences the dipole moment, the spatial extent of σ has a greater influence. This behavior is not unexpected. For a void of fixed dimensions, the smaller the charged surface area, the greater is the charges, and thus the greater the dipole moment...
Hartmann, T.; Volz, S.; Babilon, M.; Mohr, P.; Vogt, K.; Zilges, A
2003-05-19
Recently the importance of small contributions of electric dipole strength near the particle threshold to the production rates of atomic nuclei has become evident. Prior estimates concentrated on the Giant Dipole Resonance (GDR) which dominates photoabsorption in all nuclei. Extrapolations to smaller excitation energies were assumed to be sufficiently reliable. However, new measurements reveal that collective E1 strength can be found in the threshold region.
Nash, Charles A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hamm, L. Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Smith, Frank G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McCabe, Daniel J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
2014-12-19
The primary treatment of the tank waste at the DOE Hanford site will be done in the Waste Treatment and Immobilization Plant (WTP) that is currently under construction. The baseline plan for this facility is to treat the waste, splitting it into High Level Waste (HLW) and Low Activity Waste (LAW). Both waste streams are then separately vitrified as glass and poured into canisters for disposition. The LAW glass will be disposed onsite in the Integrated Disposal Facility (IDF). There are currently no plans to treat the waste to remove technetium, so its disposition path is the LAW glass. Due to the water solubility properties of pertechnetate and long half-life of ^{99}Tc, effective management of ^{99}Tc is important to the overall success of the Hanford River Protection Project mission. To achieve the full target WTP throughput, additional LAW immobilization capacity is needed, and options are being explored to immobilize the supplemental LAW portion of the tank waste. Removal of ^{99}Tc, followed by off-site disposal, would eliminate a key risk contributor for the IDF Performance Assessment (PA) for supplemental waste forms, and has potential to reduce treatment and disposal costs. Washington River Protection Solutions (WRPS) is developing some conceptual flow sheets for supplemental LAW treatment and disposal that could benefit from technetium removal. One of these flowsheets will specifically examine removing ^{99}Tc from the LAW feed stream to supplemental immobilization. To enable an informed decision regarding the viability of technetium removal, further maturation of available technologies is being performed. This report contains results of experimental ion exchange distribution coefficient testing and computer modeling using the resin SuperLig^{®} 639^{a} to selectively remove perrhenate from high ionic strength simulated LAW. It is advantageous to operate at higher concentration in order to treat the waste
Isoscalar dipole transition as a probe for asymmetric clustering
Chiba, Y; Taniguchi, Y
2015-01-01
Background: The sharp $1^-$ resonances with enhanced isoscalar dipole transition strengths are observed in many light nuclei at relatively small excitation energies, but their nature was unclear. Purpose: We show those resonances can be attributed to the cluster states with asymmetric configurations such as $\\alpha$+$^{16}{\\rm O}$. We explain why asymmetric cluster states are strongly excited by the isoscalar dipole transition. We also provide a theoretical prediction of the isoscalar dipole transitions in $^{20}{\\rm Ne}$ and $^{44}{\\rm Ti}$. Method: The transition matrix is analytically derived to clarify the excitation mechanism. The nuclear model calculations by Brink-Bloch wave function and antisymmetrized molecular dynamics are also performed to provide a theoretical prediction for $^{20}{\\rm Ne}$ and $^{44}{\\rm Ti}$. Results: It is shown that the transition matrix is as large as the Weisskopf estimate even though the ground state is an ideal shell model state. Furthermore, it is considerably amplified i...
Zhang, R.L. [Open Project of State Key Laboratory Breeding Base for Mining Disaster Prevention and Control, Shandong University of Science and Technology (China); School of Materials Science and Engineering, Shandong University of Science and Technology, 266590 Qingdao (China); Liu, Y. [School of Materials Science and Engineering, Shandong University of Science and Technology, 266590 Qingdao (China); Huang, Y.D., E-mail: rlzhit@126.com [School of Chemical Engineering and Technology, State Key laboratory of Urban Water Resource and Environment Department of Applied Chemistry, Harbin Institute of Technology, 150001 Harbin (China); Liu, L. [School of Chemical Engineering and Technology, State Key laboratory of Urban Water Resource and Environment Department of Applied Chemistry, Harbin Institute of Technology, 150001 Harbin (China)
2013-12-15
Effect of particle size and distribution of the sizing agent on the performance of carbon fiber and carbon fiber composites has been investigated. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to characterize carbon fiber surface topographies. At the same time, the single fiber strength and Weibull distribution were also studied in order to investigate the effect of coatings on the fibers. The interfacial shear strength and hygrothermal aging of the carbon fiber/epoxy resin composites were also measured. The results indicated that the particle size and distribution is important for improving the surface of carbon fibers and its composites performance. Different particle size and distribution of sizing agent has different contribution to the wetting performance of carbon fibers. The fibers sized with P-2 had higher value of IFSS and better hygrothermal aging resistant properties.
Magnetic field distribution and element concentration on the CP2 star CU Virginis
Glagolevskij, Y V; Hildebrandt, G; Scholz, G; Glagolevskij, Yu.V.
1998-01-01
We search for a relation between the published distributions of different elements and the calculated magnetic field structure, following from a dipole-quadrupole configuration, of the CP2 star CU Vir. The highest concentration of individual chemical elements on the stellar surface coincides obviously with the regions of the highest values of the magnetic field strength.
Modeling and analysis of magnetic dipoles in weak magnetic field
2008-01-01
The magnetic leakage field distribution resulting from linear defects of a tube sample in the geomagnetic field is modeled according to the magnetic dipole theory.The formula to compute the normal component of the weak magnetic field is deduced based on the spatial distribution of the magnetic dipole.The shape and characteristics of the zero line (an important criterion for magnetic memory testing) of the normal field is analyzed under different longitudinal magnetizations.Results show that the characteristics of the zero line should be considered when the metal magnetic memory testing method is used to find and locate the defect.
Paleomagnetic field strength over the last million years
Ziegler, L. B.; Johnson, C. L.; Constable, C. G.
2012-04-01
Absolute paleomagnetic intensity data derived from thermally magnetized lavas and archeological objects provide information about past geomagnetic field behavior, but the average field strength, its variability, and the expected statistical distribution of these observations remain uncertain despite growing data sets. We present statistical characterizations of the 0-1 Ma field strength, in terms of virtual axial dipole moment (VADM), using data from the PINT, MagIC, and Geomagia50 databases. Uneven temporal sampling and large age uncertainties in the available data produce biased estimates for the mean field and its statistical distribution. We describe and apply bootstrap resampling techniques to correct for these effects. The influence of material type is assessed using independent data compilations to compare Holocene data from lava flows, Submarine Basaltic Glass (SBG), and archeological objects. The comparison to SBG is inconclusive because of dating issues, but paleointensity estimates from lavas are on average about 10% higher than for archeological materials and show greater dispersion. A further interesting basis for comparison is provided by PADM2M, a continuous model of temporal variations in axial dipole moment principally derived from relative paleointensity time series, but calibrated by incorporating absolute measurements. On average, absolute VADMs are higher than the axial dipole moment estimated in PADM2M, with greater spread in the VADM distribution. Both VADM and PADM2M distribution estimates from lavas show more structure than might be expected: neither has a smooth, unimodal distribution despite the large numbers of data used in the estimation. Simulations from a stochastic model based on the geomagnetic field spectrum demonstrate that long period intensity variations can have a strong impact on the observed distributions and could plausibly explain apparent bimodality.
Nabi, Jameel-Un; Ishfaq, Mavra
2016-07-01
We calculate Gamow-Teller strength distributions for β β-decay nuclei ^{76}Ge and ^{82}Se using the deformed pn-QRPA model. We use a deformed Nilsson basis and consider pairing correlations within the deformed BCS theory. Ground state correlations and two-particle and two-hole mixing states were included in our pn-QRPA model. Our calculated strength distributions were compared with experimental data and previous calculation. The total Gamow-Teller strength and centroid placement calculated in our model compares well with the measured value. We calculate β-decay and positron capture rates on ^{76}Ge and ^{82}Se in supernovae environments and compare them to those obtained from experimental data and previous calculation. Our study shows that positron capture rates command the total weak rates at high stellar temperatures. We also calculate energy rates of β-delayed neutrons and their emission probabilities.
Prompt dipole radiation in fusion reactions
Martin, Brunella; Agodi, Concetta; Alba, Rosa; Baran, Virgil; Boiano, Alfonso; Cardella, Giuseppe; Colonna, Maria; Coniglione, Rosa; De Filippo, Enrico; Del Zoppo, Antonio; Di Toro, Massimo; Inglima, Gianni; Glodariu, Tudor; La Commara, Marco; Maiolino, Concetta; Mazzocco, Marco; Pagano, Angelo; Piattelli, Paolo; Pirrone, Sara; Rizzo, Carmelo; Romoli, Mauro; Sandoli, Mario; Santonocito, Domenico; Sapienza, Piera; Signorini, Cosimo
2008-01-01
The prompt gamma ray emission was investigated in the 16A MeV energy region by means of the 36,40Ar+96,92Zr fusion reactions leading to a compound nucleus in the vicinity of 132Ce. We show that the prompt radiation, which appears to be still effective at such a high beam energy, has an angular distribution pattern consistent with a dipole oscillation along the symmetry axis of the dinuclear system. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics.
The optimised sc dipole of SIS100 for series production
Roux, Christian; Mierau, Anna; Bleile, Alexander; Fischer, Egbert; Kaether, Florian; Körber, Boris; Schnizer, Pierre; Sugita, Kei; Szwangruber, Piotr
2017-02-01
At the international facility for antiproton and ion research (FAIR) in Darmstadt, Germany, an accelerator complex is developed for fundamental research in various fields of modern physics. In the SIS100 heavy-ion synchrotron, the main accelerator of FAIR, superconducting dipoles are used to bend the particle beam. The fast ramped dipoles are 3 m long super-ferric curved magnets operated at 4.5 K. The demands on field homogeneity required for sufficient beam stability are given by ΔB/B ≤ ±6 · 10‑4. An intense measurement program of the First of Series (FoS) dipole showed excellent quench behavior and lower than expected AC losses yielding the main load on the SIS100 cryoplant. The FoS is capable to provide a field strength of 1.9 T. However, with sophisticated measurement systems slight distortions of the dipole field were detected. Those effects were tracked down to mechanical inaccuracies of the yoke proven by appropriate geometrical measurements and simulations. After a survey on alternative fabrication techniques a magnet with a new yoke was built with substantial changes to improve the mechanical accuracy. Its characteristics concerning cryogenic losses, cold geometry and the resulting magnetic-field quality are presented and an outlook on the series production of superconducting dipoles for SIS100 is given.
1974-01-01
Stacks of SPS Dipole Magnets ready for installation in the tunnel. The SPS uses a separated function lattice with dipoles for bending and quadrupoles for focusing. The 6.2 m long normal conducting dipoles are of H-type with coils that are bent-up at the ends. There are two types, B1 (total of 360) and B2 (384). Both are for a maximum field of 1.8 Tesla and have the same outer dimensions (450x800 mm2 vxh) but with different gaps (B1: 39x129 mm2, B2: 52x92 mm2) tailored to the beam size. The yoke, made of 1.5 mm thick laminations, consists of an upper and a lower half joined together in the median plane once the coils have been inserted.
Synchronization of Interacting Quantum Dipoles
Zhu, Bihui; Xu, Minghui; Urbina, Felipe H; Restrepo, Juan G; Holland, Murray J; Rey, Ana Maria
2015-01-01
Macroscopic ensembles of radiating dipoles are ubiquitous in the physical and natural sciences. In the classical limit the dipoles can be described as damped-driven oscillators, which are able to spontaneously synchronize and collectively lock their phases. Here we investigate the correspond- ing phenomenon in the quantum regime with arrays of quantized two-level systems coupled via long-range and anisotropic dipolar interactions. Our calculations demonstrate that the dipoles may overcome the decoherence induced by quantum fluctuations and inhomogeneous couplings and evolve to a synchronized steady-state. This steady-state bears much similarity to that observed in classical systems, and yet also exhibits genuine quantum properties such as quantum correlations and quan- tum phase diffusion (reminiscent of lasing). Our predictions could be relevant for the development of better atomic clocks and a variety of noise tolerant quantum devices.
Complete Electric and Magnetic Dipole Response of 208Pb from Zero-Degree Inelastic Proton Scattering
von Neumann-Cosel, P.
2015-11-01
Small-angle polarized proton scattering including 0° off 208Pb has been studied at the RCNP cyclotron with high energy resolution of the order of 25 keV (FWHM). The complete E1 strength distribution from 5 to 20 MeV could be extracted from the data and is found to agree well with available data. New E1 strength is found in the energy region above threshold inacessible in previous experiments. The total E1 polarizability as well as the properties of the pygmy dipole resonance could be determined with high precision providing important experimental constraints on the neutron skin thickness in 208Pb and the symmetry energy of neutron-rich matter. Additionally, information on the spin-M1 strength in 208Pb was obtained. Assuming dominance of the central spin-isospinflip part of the effective proton-nucleus interaction, the B(M1) transition strength can be derived. It corresponds well with data from electromagnetic probes indicating that the reaction can provide information on the poorly known spin-M1 resonance in heavy nuclei.
CROSSING A COUPLING SPIN RESONANCE WITH AN RF DIPOLE.
BAI,M.; ROSER,T.
2001-06-18
In accelerators, due to quadrupole roll errors and solenoid fields, the polarized proton acceleration often encounters coupling spin resonances. In the Brookhaven AGS, the coupling effect comes from the solenoid partial snake which is used to overcome imperfection resonances. The coupling spin resonance strength is proportional to the amount of coupling as well as the strength of the corresponding intrinsic spin resonance. The coupling resonance can cause substantial beam polarization loss if its corresponding intrinsic spin resonance is very strong. A new method of using an horizontal rf dipole to induce a full spin flip crossing both the intrinsic and its coupling spin resonances is studied in the Brookhaven's AGS. Numerical simulations show that a full spin flip can be induced after crossing the two resonances by using a horizontal rf dipole to induce a large vertical coherent oscillation.
A class of Fourier integrals based on the electric potential of an elongated dipole.
Skianis, Georgios Aim
2014-01-01
In the present paper the closed expressions of a class of non tabulated Fourier integrals are derived. These integrals are associated with a group of functions at space domain, which represent the electric potential of a distribution of elongated dipoles which are perpendicular to a flat surface. It is shown that the Fourier integrals are produced by the Fourier transform of the Green's function of the potential of the dipole distribution, times a definite integral in which the distribution of the polarization is involved. Therefore the form of this distribution controls the expression of the Fourier integral. Introducing various dipole distributions, the respective Fourier integrals are derived. These integrals may be useful in the quantitative interpretation of electric potential anomalies produced by elongated dipole distributions, at spatial frequency domain.
Study of the pygmy dipole resonance in {sup 94}Mo using the (α,α{sup ′}γ) coincidence technique
Derya, V., E-mail: derya@ikp.uni-koeln.de [Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln (Germany); Endres, J.; Elvers, M. [Institut für Kernphysik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln (Germany); Harakeh, M.N. [Kernfysisch Versneller Instituut, Rijksuniversiteit Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Pietralla, N.; Romig, C. [Institut für Kernphysik, TU Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt (Germany); Savran, D. [ExtreMe Matter Institute EMMI and Research Division, GSI, Planckstraße 1, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, Ruth-Moufang-Straße 1, 60438 Frankfurt am Main (Germany); Scheck, M.; Siebenhühner, F. [Institut für Kernphysik, TU Darmstadt, Schlossgartenstraße 9, 64289 Darmstadt (Germany); Stoica, V.I. [Kernfysisch Versneller Instituut, Rijksuniversiteit Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); Department of Sociology/ICS, Rijksuniversiteit Groningen, Grote Rozenstraat 31, 9712 TG Groningen (Netherlands); Wörtche, H.J. [Kernfysisch Versneller Instituut, Rijksuniversiteit Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); and others
2013-05-15
The (α,α{sup ′}γ) reaction at E{sub α}=136 MeV was used to study the electric dipole response in the open-shell vibrational nucleus {sup 94}Mo below the neutron-separation threshold. The coincidence experiment has been performed at the Kernfysisch Versneller Instituut in Groningen, The Netherlands, exploiting the Big-Bite Spectrometer and an array of large volume High-Purity Germanium (HPGe) detectors. Due to the excellent energy resolution and high selectivity to transitions stemming from the pygmy dipole resonance, singles α-scattering cross sections could be determined for individual electric dipole excitations between 4 and 8 MeV. For three of the excited low-lying J{sup π}=1{sup −} states in {sup 94}Mo a γ-decay branch into the J{sup π}=2{sub 1}{sup +} state could be observed. The experiment extends the systematic studies of the pygmy dipole resonance by real-photon scattering (γ,γ{sup ′}) experiments and (α,α{sup ′}γ) experiments. Recently, a (γ,γ{sup ′}) experiment on {sup 94}Mo was performed at the Darmstadt High-Intensity Photon Setup at the S-DALINAC in Darmstadt, Germany, permitting the comparison of B(E1)↑ strength distribution and α-scattering cross sections.
Searching for electric dipole moments
Jungmann, Klaus
2013-01-01
Searches for a permanent Electric Dipole Moment (EDM) of a fundamental particle provide a wide window for the discovery of potential New Physics. Within todays Standard Model in particle physics the well established violation of CP symmetry gives rise to EDMs which are several orders of magnitude be
Particle electric dipole-moments
Pendlebury, J.M. [Sussex Univ., Brighton (United Kingdom)
1997-04-01
The incentive to detect particle electric dipole-moments, as a window on time-reversal violation, remains undiminished. Efforts to improve the measurements for the neutron, the electron and some nuclei are still making rapid progress as more powerful experimental methods are brought to bear. A new measurement for the neutron at ILL is presented. (author). 7 refs.
Schildknecht, Dieter
2016-01-01
We give a brief representation of the theoretical results from the color dipole picture, covering the total photoabsorption cross section, high-energy $J/\\psi$ photoproduction with respect to recent experimental data from the LHCb Collaboration at CERN, and ultra-high energy neutrino scattering, relevant for the ICE-CUBE experiment.
Andersen, Jørgen Bach
2006-01-01
A number of antenna topics may be treated by studying just two parallel, closely spaced electrical dipoles. They form an array and they may be coupled to form a single antenna with one port, or coupled through a coupling network to form a multiport antenna. The situations discussed are the creation...
赵长春; 张丹; 廖立兵; 孙小妮
2008-01-01
收集了15种铁-镁电气石的晶体结构数据,计算了固有电偶极矩,分析了铁-镁电气石的固有电偶极矩与铁含量、价态及分布的关系.结果显示:电气石中沿着c轴方向的固有电偶极矩随着Fe3+离子总数、特别是Y位置上Fe3+离子数的增加而减小,随Y位置上Fe2+离子数的增加而略有增加.%Crystal structure data of 15 iron-magnesium (Fe-Mg) tourmalines have been collected and their intrinsic dipole moments have been calculated. The correlation between the content, valence and distribution of Fe in Fe-Mg tourmalines and their intrinsic dipole moments have been analyzed in detail. The results show that the intrinsic dipole moments along the c axis in Fe-Mg tourmalines decrease with the increasing of their Fe3+ content, especially the content of Fe3+ in Y polyhedra, and slightly increase with the increasing of the content of Fe2+ in Y polyhedra.
Scattering from rough thin films: discrete-dipole-approximation simulations.
Parviainen, Hannu; Lumme, Kari
2008-01-01
We investigate the wave-optical light scattering properties of deformed thin circular films of constant thickness using the discrete-dipole approximation. Effects on the intensity distribution of the scattered light due to different statistical roughness models, model dependent roughness parameters, and uncorrelated, random, small-scale porosity of the inhomogeneous medium are studied. The suitability of the discrete-dipole approximation for rough-surface scattering problems is evaluated by considering thin films as computationally feasible rough-surface analogs. The effects due to small-scale inhomogeneity of the scattering medium are compared with the analytic approximation by Maxwell Garnett, and the results are found to agree with the approximation.
SSC (Superconducting Super Collider) dipole coil production tooling
Carson, J.A.; Barczak, E.J.; Bossert, R.C.; Brandt, J.S.; Smith, G.A.
1989-03-01
Superconducting Super Collider dipole coils must be produced to high precision to ensure uniform prestress and even conductor distribution within the collared coil assembly. Tooling is being prepared at Fermilab for the production of high precision 1M and 16.6M SSC dipole coils suitable for mass production. The design and construction methods builds on the Tevatron tooling and production experience. Details of the design and construction methods and measured coil uniformity of 1M coils will be presented. 4 refs., 10 figs.
The solition properties of dipole domains in superlattices
张启义; 田强
2002-01-01
The formation and propagation of dipole domains in superlattices are studied both by the modified discrete drift model and by the nonlinear schroedinger equation,the spatiotemporal distribution of the electric field and electron density are presented.The numerical results are compared with the soliton solutions of the nonlinear Schroedinger equation and analysed.It is shown that the numerical solutions agree with the soliton solutions of the nonlinear Schroedinger equation.The dipole electric-field domains in semiconductor superlattices have the properties of solitons.
2002-01-01
% IS353 \\\\ \\\\ Due to its importance in fundamental physics and astrophysics, a great effort both theoretically and experimentally is devoted to study Gamow Teller (GT)-strength. The GT-strength and its distribution play a key role in late stellar evolution. During the pre-supernova core-collapse of massive stars, the electron capture and nuclear $\\beta$ -decay determine the electron-to-baryon ratio, which influences the infall dynamics and the mass of the final core. The cross-section of the charge-exchange reaction at forward angles with energies above 100~MeV is expected to be proportional to the squares of Fermi and GT matrix elements. This proportionality should provide a Q-value free method to probe the weak interaction strength and renormalization effects in nuclei. Thus charge-exchange reactions are often used to determine the experimental GT-strength. However, the connection between the GT-strength and the cross-section of the charge-exchange reaction is partially model-dependent and the question aris...
Excitation of pygmy dipole resonance in neutron-rich nuclei via Coulomb and nuclear fields
A Vitturi; E G Lanza; M V Andrés; F Catara; D Gambacurta
2010-07-01
We study the nature of the low-lying dipole strength in neutron-rich nuclei, often associated with the pygmy dipole resonance. The states are described within the Hartree–Fock plus RPA formalism, using different parametrizations of the Skyrme inter-action. We show how the information from combined reaction processes involving the Coulomb and different mixtures of isoscalar and isovector nuclear interactions can provide a clue to reveal the characteristic features of these states.
An equivalent magnetic dipoles model for quantitative damage recognition of broken wire
TAN Ji-wen; ZHAN Wei-xia; LI Chun-jing; WEN Yan; SHU Jie
2005-01-01
By simplifying saturatedly magnetized wire-rope to magnetic dipoles of the same magnetic field strength, an equivalent magnetic dipoles model is developed and the measuring principle for recognising damage of broken wire was presented. The relevant calculation formulas were also deduced. A composite solution method about nonlinear optimization was given. An example was given to illustrate the use of the equivalent magnetic dipoles method for quantitative damage recognition, and demonstrates that the result of this method is consistent with the real situation, so the method is valid and practical.
Nature of low-lying electric dipole resonance excitations in 74Ge
Negi, D; Lanza, E G; Litvinova, E; Vitturi, A; Bark, R A; Bernstein, L A; Bleuel, D L; Bvumbi, S; Bucher, T D; Daub, B H; Dinoko, T S; Easton, J L; Gorgen, A; Guttormsen, M; Jones, P; Kheswa, B V; Khumalo, N A; Larsen, A C; Lawrie, E A; Lawrie, J J; Majola, S N T; Masiteng, L P; Nchodu, M R; Ndayishimye, J; Newman, R T; Noncolela, S P; Orce, J N; Papka, P; Pellegri, L; Renstrøm, T; Roux, D G; Schwengner, R; Shirinda, O; Siem, S
2016-01-01
Isospin properties of dipole excitations in 74 Ge are investigated using the ({\\alpha},{\\alpha}'{\\gamma}) reaction and compared to ({\\gamma},{\\gamma}) data. The results indicate that the dipole excitations in the energy region of 6 to 9 MeV adhere to the scenario of the recently found splitting of the region of dipole excitations into two separated parts: one at low energy, being populated by both isoscalar and isovector probes, and the other at high energy, excited only by the electromagnetic probe. Relativistic quasiparticle time blocking approximation (RQTBA) calculations show a reduction in the isoscalar E1 strength with an increase in excitation energy, which is consistent with the measurement.
Refutation of stability proofs for dipole vortices
Nycander, J.
1992-01-01
Five stability proofs for dipole vortices (modons) that have been presented by various authors are examined. It is shown that they are all incorrect, and that westward-propagating dipoles are in fact unstable, in contradiction to some of the proofs.......Five stability proofs for dipole vortices (modons) that have been presented by various authors are examined. It is shown that they are all incorrect, and that westward-propagating dipoles are in fact unstable, in contradiction to some of the proofs....
王玉玲; 能昌信; 王彦文; 董路; 徐亚
2013-01-01
To compare the anti-noise performance of the wenner array with that of the dipole-dipole array using the electrical resistivity,the potential distributions of the two arrays in the homogeneous space were derived based on the basic electric field principles of the point current source.The ratio was set to 3∶1 for the signal strength of the wenner (alpha) to the dipole-dipole when the n factor in the dipole-dipole array was set as 1.The ratio would be even larger,when greater n values were used.A field survey was carried out in a contaminated site.The results showed that 12.10％ of the data collected by the dipole-dipole array were removed,while the percentage was only 0.28％ in the wenner array according to the repeat error and data value when a larger factor n was used that results in the noisy data.By analyzing the data collected by the two arrays,it is concluded that the dataset of the wenner array can be superior to that of the dipole-dipole array.Consequently,the wenner array should be applied if the background noise is high in the actual contaminated sites survey.%为比较2种电阻率法污染场地探测装置——温纳和偶极装置的抗噪声性能,基于点电流源电场分布原理进行理论推导,研究了理想均匀半空间的理论电位取值,并在重庆一废弃化工厂进行实际场地探测比较.结果表明,采用相同极距的2种探测装置,温纳装置采集的信号强度为偶极装置的3倍以上,具有更强的在抗噪声性能.在实际探测中,温纳装置仅有0.28％的数据由于数据质量较差被移除,而偶极装置的这一数据占12.10％,可见温纳装置比偶极装置具有更好的抗噪声性能.因此,在实际污染场地探测中,如果场地的噪声干扰严重,应优先选择采用温纳装置进行探测.
Quantum Zeno suppression of dipole-dipole forces
Wüster, Sebastian
2016-01-01
We consider inter-atomic forces due to resonant dipole-dipole interactions within a dimer of highly excited Rydberg atoms, embedded in an ultra-cold gas. These forces rely on a coherent superposition of two-atom electronic states, which is destroyed by continuous monitoring of the dimer state through a detection scheme utilizing controllable interactions with the background gas atoms. We show that this intrinsic decoherence of the molecular energy surface can gradually deteriorate a repulsive dimer state, causing a mixing of attractive and repulsive character. For sufficiently strong decoherence, a Zeno-like effect causes a complete arrest of interatomic forces. We finally show how short decohering pulses can controllably redistribute population between the different molecular energy surfaces.
Effects of dipole-dipole interaction on entanglement transfer
Guo Hong; Xiong Heng-Na
2008-01-01
A system consisting of two different atoms interacting with a two-mode vacuum, where each atom is resonant only with one cavity mode, is considered.The effects of dipole-dipole (dd) interaction between two atoms on the atom-atom entanglement and mode-mode entanglement are investigated. For a weak dd interaction, when the atoms are initially separable, the entanglement between them can be induced by the dd interaction, and the entanglement transfer between the atoms and the modes occurs efficiently; when the atoms are initially entangled, the entanglement transfer is almost not influenced by the dd interaction. However, for a strong dd interaction, it is difficult to transfer the entanglement from the atoms to the modes, but the atom-atom entanglement can be maintained when the atoms are initially entangled.
Optics effects of splitting dipole magnets into several thin lenses
Leunissen, L H A
1998-01-01
The evaluation of the dynamic aperture and the calculation of non linear optics parameters have been made so far with the simplest model of dipole, i.e. a single thin lens positioned at the centre of each thick dipole. It was shown recently that the non-linear chromaticity decreases significantly when the thick lens is represented by two thin lenses or more instead of one. In this note the study is extended to amplitude detuning and dynamic aperture. Unlike the observation reported on non-linear chromatic detuning we find no significant changes for the dynamic aperture and amplitude d etuning when the dipole magnets are split in more than one thin lens. Furthermore, non-uniform azimuthal distribution of the multipoles inside the dipole is shown not to change the above-mentio ned results. In both cases, the influence of the beta-funtions is expected to give large effect for a given dipole. However, integrated over one cell this effect is shown to compensate to a large extent. erture reported on non-linear chro...
Valence Topological Charge-Transfer Indices for Dipole Moments
Francisco Torrens
2003-01-01
Full Text Available New valence topological charge-transfer indices are applied to the calculation of dipole moments. The algebraic and vector semisum charge-transfer indices are defined. The combination of the charge-transfer indices allows the estimation of the dipole moments. The model is generalized for molecules with heteroatoms. The ability of the indices for the description of the molecular charge distribution is established by comparing them with the dipole moments of a homologous series of phenyl alcohols. Linear and non-linear correlation models are obtained. The new charge-transfer indices improve the multivariable non-linear regression equations for the dipole moment. When comparing with previous results, the variance decreases 92%. No superposition of the corresponding GkÃ¢Â€Â“Jk and GkV Ã¢Â€Â“ JkV pairs is observed. This diminishes the risk of co-linearity. Inclusion of the oxygen atom in the p-electron system is beneficial for the description of the dipole moment, owing to either the role of the additional p orbitals provided by the heteroatom or the role of steric factors in the p-electron conjugation. Linear and non-linear correlations between the fractal dimension and various descriptors point not only to a homogeneous molecular structure but also to the ability to predict and tailor drug properties.
Noncommutative Dipole Field Theories And Unitarity
Chiou, D W; Chiou, Dah-Wei; Ganor, Ori J.
2004-01-01
We extend the argument of Gomis and Mehen for violation of unitarity in field theories with space-time noncommutativity to dipole field theories. In dipole field theories with a timelike dipole vector, we present 1-loop amplitudes that violate the optical theorem. A quantum mechanical system with nonlocal potential of finite extent in time also shows violation of unitarity.
Perturbative Odderon in the Dipole Model
Kovchegov, Yu V; Wallon, S; Kovchegov, Yuri V.; Szymanowski, Lech; Wallon, Samuel
2003-01-01
We show that, in the framework of Mueller's dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a $C$-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions $E^{n,\
Prompt dipole gamma-ray emission in fusionlike heavy-ion reactions
Pierroutsakou, D; Di Pietro, M; Mordente, R; Ordine, A; Romoli, M; De Rosa, A; Inglima, G; La Commara, M; Martin, B; Roca, V; Sandoli, M; Trotta, M; Vardaci, E; Ming, R; Rizzo, F; Soramel, F; Stroe, L
2003-01-01
The sup 3 sup 2 S+ sup 1 sup 0 sup 0 Mo and sup 3 sup 6 S+ sup 9 sup 6 Mo fusionlike reactions were studied at incident energy of E sub l sub a sub b =298 MeV and 320 MeV, respectively, with the aim of probing the influence of the entrance channel charge asymmetry on the dipole gamma-ray emission. The excitation energy and spin distribution of the compound nucleus created in these reactions were identical, the only difference being associated with the unequal charge asymmetry of the two entrance channels. High-energy gamma-rays were detected in an array of 9 seven-pack BaF sub 2 clusters. Coincidence with fusionlike residues detected in four PPAC ensured the selection of central reaction events. By studying the differential gamma-ray multiplicity associated with the two reactions it was shown that the dipole strength excited in the compound nucleus increases with the entrance channel charge asymmetry. From the linearized spectra, the increase of the GDR gamma-ray intensity was found to be propor to 25% for th...
Critical behavior of isotropic three-dimensional systems with dipole-dipole interactions
Belim, S. M., E-mail: sbelim@mail.ru [Dostoevsky Omsk State University (Russian Federation)
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.
Confronting Higgcision with Electric Dipole Moments
Cheung, Kingman; Senaha, Eibun; Tseng, Po-Yan
2014-01-01
Current data on the signal strengths and angular spectrum of the 125.5 GeV Higgs boson still allow a CP-mixed state, namely, the pseudoscalar coupling to the top quark can be as sizable as the scalar coupling: $C_u^S \\approx C_u^P =1/2$. CP violation can then arise and manifest in sizable electric dipole moments (EDMs). In the framework of two-Higgs-doublet models, we not only update the Higgs precision (Higgcision) study on the couplings with the most updated Higgs signal strength data, but also compute all the Higgs-mediated contributions from the 125.5 GeV Higgs boson to the EDMs, and confront the allowed parameter space against the existing constraints from the EDM measurements of Thallium, neutron, Mercury, and Thorium monoxide. We found that the combined EDM constraints restrict the pseudoscalar coupling to be less than about $10^{-2}$, unless there are contributions from other Higgs bosons, supersymmetric particles, or other exotic particles that delicately cancel the current Higgs-mediated contributio...
Confronting Higgcision with electric dipole moments
Cheung, Kingman; Lee, Jae Sik; Senaha, Eibun; Tseng, Po-Yan
2014-06-01
Current data on the signal strengths and angular spectrum of the 125.5 GeV Higgs boson still allow a CP-mixed state, namely, the pseudoscalar coupling to the top quark can be as sizable as the scalar coupling: C {/u S } ≈ C {/u P } = 1/2. CP violation can then arise and manifest in sizable electric dipole moments (EDMs). In the framework of two-Higgs-doublet models, we not only update the Higgs precision (Higgcision) study on the couplings with the most updated Higgs signal strength data, but also compute all the Higgs-mediated contributions from the 125.5 GeV Higgs boson to the EDMs, and confront the allowed parameter space against the existing constraints from the EDM measurements of Thallium, neutron, Mercury, and Thorium monoxide. We found that the combined EDM constraints restrict the pseudoscalar coupling to be less than about 10-2, unless there are contributions from other Higgs bosons, supersymmetric particles, or other exotic particles that delicately cancel the current Higgs-mediated contributions.
Equivalent Dipole Vector Analysis for Detecting Pulmonary Hypertension
Harlander, Matevz; Salobir, Barbara; Toplisek, Janez; Schlegel, Todd T.; Starc, Vito
2010-01-01
Various 12-lead ECG criteria have been established to detect right ventricular hypertrophy as a marker of pulmonary hypertension (PH). While some criteria offer good specificity they lack sensitivity because of a low prevalence of positive findings in the PH population. We hypothesized that three-dimensional equivalent dipole (ED) model could serve as a better detection tool of PH. We enrolled: 1) 17 patients (12 female, 5 male, mean age 57 years, range 19-79 years) with echocardiographically detected PH (systolic pulmonary arterial pressure greater than 35 mmHg) and no significant left ventricular disease; and 2) 19 healthy controls (7 female, 12 male, mean age 44, range 31-53 years) with no known heart disease. In each subject we recorded a 5-minute high-resolution 12-lead conventional ECG and constructed principal signals using singular value decomposition. Assuming a standard thorax dimension of an adult person with homogenous and isotropic distribution of thorax conductance, we determined moving equivalent dipoles (ED), characterized by the 3D location in the thorax, dipolar strength and the spatial orientation, in time intervals of 5 ms. We used the sum of all ED vectors in the second half of the QRS complex to derive the amplitude of the right-sided ED vector (RV), if the orientation of ED was to the right side of the thorax, and in the first half the QRS to derive the amplitude of the left-sided vector (LV), if the orientation was leftward. Finally, the parameter RV/LV ratio was determined over an average of 256 complexes. The groups differed in age and gender to some extent. There was a non-significant trend toward higher RV in patients with PH (438 units 284) than in controls (280 plus or minus 140) (p = 0.066) but the overlap was such that RV alone was not a good predictor of PH. On the other hand, the RV/LV ratio was a better predictor of PH, with 11/17 (64.7%) of PH patients but only in 1/19 (5.3%) control subjects having RV/LV ratio greater than or
MD 349: Impedance Localization with AC-dipole
Biancacci, Nicolo; Metral, Elias; Salvant, Benoit; Papotti, Giulia; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department
2016-01-01
The purpose of this MD is to measure the distribution of the transverse impedance of the LHC by observing the phase advance variation with intensity between the machine BPMs. Four injected bunches with different intensities are excited with an AC dipole and the turn by turn data is acquired from the BPM system. Through post-processing analysis the phase variation along the machine is depicted and, from this information, first conclusions of the impedance distribution can be drawn.
Mechanics of nonplanar membranes with force-dipole activity
Lomholt, Michael Andersen
2006-01-01
A study is made of how active membrane proteins can modify the long wavelength mechanics of fluid membranes. The activity of the proteins is modelled as disturbing the protein surroundings through nonlocal force distributions of which a force-dipole distribution is the simplest example. An analyt...... contributions to mechanical properties such as tension and bending moments become apparent. It is also explained how the activity can induce a hydrodynamic attraction between the active proteins in the membrane....
Systematics of strength function sum rules
Johnson, Calvin W.
2015-11-01
Sum rules provide useful insights into transition strength functions and are often expressed as expectation values of an operator. In this letter I demonstrate that non-energy-weighted transition sum rules have strong secular dependences on the energy of the initial state. Such non-trivial systematics have consequences: the simplification suggested by the generalized Brink-Axel hypothesis, for example, does not hold for most cases, though it weakly holds in at least some cases for electric dipole transitions. Furthermore, I show the systematics can be understood through spectral distribution theory, calculated via traces of operators and of products of operators. Seen through this lens, violation of the generalized Brink-Axel hypothesis is unsurprising: one expects sum rules to evolve with excitation energy. Furthermore, to lowest order the slope of the secular evolution can be traced to a component of the Hamiltonian being positive (repulsive) or negative (attractive).
Systematics of strength function sum rules
Johnson, Calvin W., E-mail: cjohnson@mail.sdsu.edu
2015-11-12
Sum rules provide useful insights into transition strength functions and are often expressed as expectation values of an operator. In this letter I demonstrate that non-energy-weighted transition sum rules have strong secular dependences on the energy of the initial state. Such non-trivial systematics have consequences: the simplification suggested by the generalized Brink–Axel hypothesis, for example, does not hold for most cases, though it weakly holds in at least some cases for electric dipole transitions. Furthermore, I show the systematics can be understood through spectral distribution theory, calculated via traces of operators and of products of operators. Seen through this lens, violation of the generalized Brink–Axel hypothesis is unsurprising: one expects sum rules to evolve with excitation energy. Furthermore, to lowest order the slope of the secular evolution can be traced to a component of the Hamiltonian being positive (repulsive) or negative (attractive).
Systematics of strength function sum rules
Calvin W. Johnson
2015-11-01
Full Text Available Sum rules provide useful insights into transition strength functions and are often expressed as expectation values of an operator. In this letter I demonstrate that non-energy-weighted transition sum rules have strong secular dependences on the energy of the initial state. Such non-trivial systematics have consequences: the simplification suggested by the generalized Brink–Axel hypothesis, for example, does not hold for most cases, though it weakly holds in at least some cases for electric dipole transitions. Furthermore, I show the systematics can be understood through spectral distribution theory, calculated via traces of operators and of products of operators. Seen through this lens, violation of the generalized Brink–Axel hypothesis is unsurprising: one expects sum rules to evolve with excitation energy. Furthermore, to lowest order the slope of the secular evolution can be traced to a component of the Hamiltonian being positive (repulsive or negative (attractive.
Technology of superconducting accelerator dipoles
Hassenzahl, W.V.; Meuser, R.B.; Taylor, C.
1983-06-01
We discuss accelerator dipoles and their characteristics. Other types of magnets, in particular bubble chamber magnets have been quite successful. Their performance is based on cryogenic stability which is addressed only briefly in this chapter. This type of stability is not available to the accelerator designer because of the large quantities of copper or other stabilizer that would reduce the current density in the windings to an unacceptably low value.
Radiating dipoles in photonic crystals
Busch, Kurt; Vats, Nipun; John, Sajeev; Sanders, Barry C.
2000-01-01
The radiation dynamics of a dipole antenna embedded in a Photonic Crystal are modeled by an initially excited harmonic oscillator coupled to a non--Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the Photonic Crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra ar...
Aurière, M; Silvester, J; Lignières, F; Bagnulo, S; Bale, K; Dintrans, B; Donati, J F; Folsom, C P; Gruberbauer, M; Hoa, A Hui Bon; Jeffers, S; Johnson, N; Landstreet, J D; Lebre, A; Lüftinger, T; Marsden, S; Mouillet, D; Naseri, S; Paletou, F; Petit, P; Power, J; Rincon, F; Strasser, S; Toque, N
2007-01-01
We have investigated a sample of 28 well-known spectroscopically-identified magnetic Ap/Bp stars, with weak, poorly-determined or previously undetected magnetic fields, with the aim of exploring the weak part of the magnetic field distribution of Ap/Bp stars. Using the MuSiCoS and NARVAL spectropolarimeters we have obtained 282 LSD Stokes V signatures of our 28 sample stars. All stars were detected, showing clearly that when observed with sufficient precision, all firmly classified Ap/Bp stars show detectable surface magnetic fields. To better characterise the surface magnetic field intensities and geometries of the sample, we have inferred the dipolar field intensity and the magnetic obliquity. The distribution of derived dipole strengths for these stars exhibits a plateau at about 1 kG, falling off to larger and smaller field strengths. Remarkably, in this sample of stars selected for their presumably weak magnetic fields, we find only 2 stars for which the derived dipole strength is weaker than 300 G. We i...
Monolayer patterning using ketone dipoles.
Kim, Min Kyoung; Xue, Yi; Pašková, Tereza; Zimmt, Matthew B
2013-08-14
The self-assembly of multi-component monolayers with designed patterns requires molecular recognition among components. Dipolar interactions have been found to influence morphologies of self-assembled monolayers and can affect molecular recognition functions. Ketone groups have large dipole moments (2.6 D) and are easily incorporated into molecules. The potential of ketone groups for dipolar patterning has been evaluated through synthesis of two 1,5-disubstituted anthracenes bearing mono-ketone side chains, STM characterization of monolayers self-assembled from their single and two component solutions and molecular mechanics simulations to determine their self-assembly energetics. The results reveal that (i) anthracenes bearing self-repulsive mono-ketone side chains assemble in an atypical monolayer morphology that establishes dipolar attraction, instead of repulsion, between ketones in adjacent side chains; (ii) pairs of anthracene molecules whose self-repulsive ketone side chains are dipolar complementary spontaneously assemble compositionally patterned monolayers, in which the two components segregate into neighboring, single component columns, driven by side chain dipolar interactions; (iii) compositionally patterned monolayers also assemble from dipolar complementary anthracene pairs that employ different dipolar groups (ketones or CF2 groups) in their side chains; (iv) the ketone group, with its larger dipole moment and size, provides comparable driving force for patterned monolayer formation to that of the smaller dipole, and smaller size, CF2 group.
Constraints on exotic dipole-dipole couplings between electrons at the micrometer scale
Kotler, Shlomi; Kimball, Derek F Jackson
2015-01-01
New constraints on exotic dipole-dipole interactions between electrons at the micrometer scale are established, based on a recent measurement of the magnetic interaction between two trapped $^{88}$Sr$^+$ ions. For light bosons (mass $\\le$ 0.1 eV) we obtain $90\\%$ confidence intervals on pseudo-scalar and axial-vector mediated interaction strengths of $\\left|g_P^eg_P^e/4\\pi\\hbar c\\right|\\le 1.5\\times 10^{-3}$ and $\\left|g_A^eg_A^e/4\\pi\\hbar c\\right|\\le 1.2\\times 10^{-17}$, respectively. These bounds significantly improve on previous work for this mass range. Assuming CPT invariance, these constraints are compared to those on anomalous electron-positron interactions, derived from positronium hyperfine spectroscopy. For axial-vector mediated interaction the electron-electron constraints are six orders of magnitude more stringent than the electron-positron constraints. Bounds on torsion gravity are also derived and compared with previous work performed at different length scales.
Constraints on Exotic Dipole-Dipole Couplings between Electrons at the Micrometer Scale
Kotler, Shlomi; Ozeri, Roee; Kimball, Derek F. Jackson
2015-08-01
New constraints on exotic dipole-dipole interactions between electrons at the micrometer scale are established, based on a recent measurement of the magnetic interaction between two trapped 88Sr+ ions. For light bosons (mass≤0.1 eV ) we obtain a 90% confidence interval for an axial-vector-mediated interaction strength of |gAegAe/4 π ℏc | ≤1.2 ×10-17 . Assuming C P T invariance, this constraint is compared to that on anomalous electron-positron interactions, derived from positronium hyperfine spectroscopy. We find that the electron-electron constraint is 6 orders of magnitude more stringent than the electron-positron counterpart. Bounds on pseudoscalar-mediated interaction as well as on torsion gravity are also derived and compared with previous work performed at different length scales. Our constraints benefit from the high controllability of the experimental system which contained only two trapped particles. It therefore suggests a useful new platform for exotic particle searches, complementing other experimental efforts.
Nabi, Jameel-Un
2012-01-01
This paper reports on the microscopic calculation of ground and excited states Gamow-Teller (GT) strength distributions, both in the electron capture and electron decay direction, for $^{54,55,56}$Fe. The associated electron and positron capture rates for these isotopes of iron are also calculated in stellar matter. These calculations were recently introduced and this paper is a follow-up which discusses in detail the GT strength distributions and stellar capture rates of key iron isotopes. The calculations are performed within the framework of the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic \\textit{state-by-state} calculation of GT strength functions and stellar capture rates which greatly increases the reliability of the results. For the first time experimental deformation of nuclei are taken into account. In the core of massive stars isotopes of iron, $^{54,55,56}$Fe, are considered to be key players in decreasing the electron-to-baryon ...
Nabi, Jameel-Un; 10.1103/PhysRevC.76.055803
2011-01-01
Gamow-Teller (GT) strength transitions are an ideal probe for testing nuclear structure models. In addition to nuclear structure, GT transitions in nuclei directly affect the early phases of Type Ia and Type-II supernovae core collapse since the electron capture rates are partly determined by these GT transitions. In astrophysics, GT transitions provide an important input for model calculations and element formation during the explosive phase of a massive star at the end of its life-time. Recent nucleosynthesis calculations show that odd-odd and odd-A nuclei cause the largest contribution in the rate of change of lepton-to-baryon ratio. In the present manuscript, we have calculated the GT strength distributions and electron capture rates for odd-odd nucleus 50V by using the pn-QRPA theory. At present 50V is the first experimentally available odd-odd nucleus in fp-shell nuclei. We also compare our GT strength distribution with the recently measured results of a 50V(d,2He)50Ti experiment, with the earlier work ...
Helical Dipole Magnets for Polarized Protons in RHIC
Syphers, M.; Courant, E.; Fischer, W.; Luccio, A.; Mariam, F.; Peggs, S.; Pilat, F.; Roser, T.; Tepikian, S.; Tsoupas, N.; Willen, E.; Katayama, T.; Hatanaka, K.; Kawaguchi, T.; Okamura, M.; Tominaka, T.; Wu, H.; Ptitsin, V.; Shatunov, Y.
1997-05-01
The Brookhaven Relativistic Heavy Ion Collider (RHIC) will be able to support experiments using polarized proton beams. Siberian Snakes are used to maintain polarization in this high energy superconducting collider. To make efficient use of available space while taking advantage of high field superconducting magnets, 4 Tesla helical dipole magnets will be used. These magnets generate a central dipole field in which the field direction rotates through 360^circ about the longitudinal axis over the length of the device. An arrangement of four such magnets can produce the desired change in the spin direction while keeping the proton orbit outside of the ``Snake'' unaltered. Similar magnet arrangements will be used to produce longitudinal polarization at the two major interaction points in RHIC. The basic requirements and layout of these magnets are described, as well as tolerances on field quality and integrated field strengths. First results of tests of prototype helical magnets will be discussed.
The permanent and induced magnetic dipole moment of the moon
Russell, C. T.; Coleman, P. J., Jr.; Lichtenstein, B. R.; Schubert, G.
1974-01-01
Magnetic field observations with the Apollo 15 subsatellite have been used to deduce the components of both the permanent and induced lunar dipole moments in the orbital plane. The present permanent lunar magnetic dipole moment in the orbital plane is less than 1.3 times ten to the eighteenth power gauss-cu cm. Any uniformly magnetized near surface layer is therefore constrained to have a thickness-magnetization product less than 2.5 emu-cm per g. The induced moment opposes the external field, implying the existence of a substantial lunar ionosphere with a permeability between 0.63 and 0.85. Combining this with recent measures of the ratio of the relative field strength at the ALSEP and Explorer 35 magnetometers indicates that the global lunar permeability relative to the plasma in the geomagnetic tail lobes is between 1.008 and 1.03.
Driving Rabi oscillations at the giant dipole resonance in xenon
Pabst, Stefan; Santra, Robin
2015-01-01
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 $4d$ ionization threshold. We find that intensities around 10$^{18}$ W/cm$^2$ 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 form of Autler-Townes splittings extending over several tens of electronvolt.
Clinical utility of current-generation dipole modelling of scalp EEG.
Plummer, C; Litewka, L; Farish, S; Harvey, A S; Cook, M J
2007-11-01
To investigate the clinical utility of current-generation dipole modelling of scalp EEG in focal epilepsies seen commonly in clinical practice. Scalp EEG recordings from 10 patients with focal epilepsy, five with Benign Focal Epilepsy of Childhood (BFEC) and five with Mesial Temporal Lobe Epilepsy (MTLE), were used for interictal spike dipole modelling using Scan 4.3 and CURRY 5.0. Optimum modelling parameters for EEG source localisation (ESL) were sought by the step-wise application of various volume conductor (forward) and dipole (inverse) models. Best-fit ESL solutions (highest explained forward-fit to measured data variance) were used to characterise best-fit forward and inverse models, regularisation effect, additional electrode effect, single-to-single spike and single-to-averaged spike variability, and intra- and inter-operator concordance. Inter-parameter relationships were examined. Computation times and interface problems were recorded. For both BFEC and MTLE, the best-fit forward model was the finite element method interpolated (FEMi) model, while the best-fit single dipole models were the rotating non-regularised and the moving regularised models. When combined, these forward-inverse models appeared to offer clinically meaningful ESL results when referenced to an averaged cortex overlay, best-fit dipoles localising to the central fissure region in BFEC and to the basolateral temporal region in MTLE. Single-to-single spike and single-to-averaged spike measures of concordance for dipole location and orientation were stronger for BFEC versus MTLE. The use of an additional pair of inferior temporal electrodes in MTLE directed best-fit dipoles towards the basomesial temporal region. Inverse correlations were noted between unexplained variance (RD) and dipole strength (Amp), RD and signal to noise ratio (SNR), and SNR and confidence ellipsoid (CE) volume. Intra- and inter-operator levels of agreement were relatively robust for dipole location and orientation
RHIC spin flipper AC dipole controller
Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.
2011-03-28
The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.
New probe of M1 and E1 strengths in GDR regions
Hayakawa, T. [Japan Atomic Energy Agency and National Astronomical Observatory in Japan (Japan); Ogata, K. [RCNP, Osaka University (Japan); Miyamoto, S.; Mochizuki, T.; Horikawa, K.; Amano, S. [University of Hyogo (Japan); Imazaki, K.; Li, D.; Izawa, Y. [Institute for Laser Technology (Japan); Chiba, S. [Tokyo Institute of Technology (Japan)
2014-05-02
The M1 strengths (or level density of 1{sup +} states) are of importance for estimation of interaction strengths between neutrinos and nuclei for the study of the supernova neutrino-process. In 1957, Agodi predicted theoretically angular distribution of neutrons emitted from states excited via dipole transitions with linearly polarized gamma-ray beam at the polar angle of θ=90° should be followed by a simple function, a + b cos(2φ), where φ, is azimuthal angel. However, this theoretical prediction has not been verified over the wide mass region except for light nuclei as deuteron. We have measured neutron angular distributions with (polarized gamma, n) reactions on Au, Nal, and Cu. We have verified the Agodi's prediction for the first time over the wide mass region. This suggests that (polarized gamma, n) reactions may be useful tools to study M1 strengths in giant resonance regions.
Koehler, P. E.; Bečvář, F.; Krtička, M.; Harvey, J. A.; Guber, K. H.
2011-01-01
A recent Letter attempted to reconcile the disagreement between neutron resonance data and random matrix theory (RMT). To this end, a new formula was derived for transforming measured ({\\Gamma}_{{\\lambda}n}) to reduced ({\\Gamma}_{{\\lambda}n}^0) neutron widths for s-wave resonances ({\\lambda}=1,2,...) in nuclides near peaks of the s-wave neutron strength function. In this Comment, we show that such a rescaling would not, in general, be expected to reconcile the type of disagreement observed, a...
Koehler, P E; Krtička, M; Harvey, J A; Guber, K H
2011-01-01
A recent Letter attempted to reconcile the disagreement between neutron resonance data and random matrix theory (RMT). To this end, a new formula was derived for transforming measured ({\\Gamma}_{{\\lambda}n}) to reduced ({\\Gamma}_{{\\lambda}n}^0) neutron widths for s-wave resonances ({\\lambda}=1,2,...) in nuclides near peaks of the s-wave neutron strength function. In this Comment, we show that such a rescaling would not, in general, be expected to reconcile the type of disagreement observed, and demonstrate that indeed it does not for the specific cases in question. Hence, the disagreements between RMT and these data remain.
The sign of the dipole-dipole potential by axion exchange
Daido, Ryuji; Takahashi, Fuminobu
2017-09-01
We calculate a dipole-dipole potential between fermions mediated by a light pseudoscalar, axion, paying a particular attention to the overall sign. While the sign of the potential is physical and important for experiments to discover or constrain the axion coupling to fermions, there is often a sign error in the literature. The purpose of this short note is to clarify the sign issue of the axion-mediated dipole-dipole potential. As a by-product, we find a sign change of the dipole-dipole potenital due to the different spin of the mediating particle.
Kamohara, Masumi; Izumi, Yudai; Tanaka, Masafumi; Okamoto, Keiko; Tanaka, Masahito; Kaneko, Fusae; Kodama, Yoko; Koketsu, Toshiyuki; Nakagawa, Kazumichi
2008-10-01
Absorption spectra of thin films of glycine (Gly), alanine (Ala), valine (Val), serine (Ser), leucine (Leu), phenylalanine (Phe) and methinine (Met) were measured in absolute values of absorption cross section σ( E) for the photon energy E from 3 to 250 eV. We translated σ( E) into the optical oscillator strength distribution df/dE and we examined the Thomas-Reiche-Kuhn sum rule [Hirschfelder, J.O., Curtiss, C.F., Bird, R.B., 1954. Molecular Theory of Gases and Liquids. Wiley, New York, p. 890]. We concluded that T-R-K sum rule was correctly applicable for such relatively large size of biomolecules.
Exploring the Dipole Polarizability of $^{11}$Li at REX-ISOLDE
2002-01-01
Dipole polarizability refers to the effect of the excitation to negative parity states through the electric dipole interaction. In nuclear physics dipole polarizability has not yet played a major role. For nuclei close to the drip lines where the separation energies of neutrons (or protons) are small, a substantial part of the dipole strength function occurs at low excitation energies. We here propose to investigate this effect by measuring elastic scattering at energies close to the Coulomb barrier. REX-ISOLDE together with the new improved yields of $^{11}$Li provides the ideal setting for this experiment. We ask for a total of 24 shifts with proton beam plus 3 shifts of stable beam from a Ta-foil target.
On the collectivity of Pygmy Dipole Resonance within schematic TDA and RPA models
Baran, V; Colonna, M; Di Toro, M; Croitoru, A; Nicolin, A I
2014-01-01
Within schematic models based on the Tamm-Dancoff Approximation and the Random-Phase Approximation with separable interactions, we investigate the physical conditions which determine the emergence of the Pygmy Dipole Resonance in the E1 response of atomic nuclei. We find that if some particle-hole excitation manifests a different, weaker residual interaction, an additional mode will appear, with an energy centroid closer to the distance between two major shells and therefore well below the Giant Dipole Resonance. This state, together with Giant Dipole Resonance, exhausts all the transition strength in the Tamm-Dancoff Approximation and all the Energy Weighted Sum Rule in the Random-Phase Approximation. These features suggest a collective nature for this mode which we identify with the Pygmy Dipole Resonance.
Bound states of a light atom and two heavy dipoles in two dimensions
Rosa, D S; Jensen, A S; Krein, G; Yamashita, M T
2016-01-01
We study a three-body system, formed by a light particle and two identical heavy dipoles, in two dimensions in the Born-Oppenheimer approximation. We present the analytic light-particle wave function resulting from an attractive zero-range potential between the light and each of the heavy particles. It expresses the large-distance universal properties which must be reproduced by all realistic short-range interactions. We calculate the three-body spectrum for zero heavy-heavy interaction as function of light to heavy mass ratio. We discuss the relatively small deviations from Coulomb estimates and the degeneracies related to radial nodes and angular momentum quantum numbers. We include a repulsive dipole-dipole interaction and investigate the three-body solutions as functions of strength and dipole direction. Avoided crossings occur between levels localized in the emerging small and large-distance minima, respectively. The characteristic exchange of properties like mean square radii are calculated. Simulation ...
LOG PERIODIC DIPOLE ARRAY WITH PARASITIC ELEMENTS
The design and measured characteristics of dipole and monopole versions of a log periodic array with parasitic elements are discussed. In a dipole...array with parasitic elements, these elements are used in place of every alternate dipole, thereby eliminating the need of a twisted feed arrangement...for the elements to obtain log periodic performance of the anntenna. This design with parasitic elements lends itself to a monopole version of the
Maiti, A; Gee, R H; Hoffman, D; Fried, L E
2007-08-22
Pressed-powdered crystallites of intrinsically anisotropic materials have been shown to undergo irreversible volume expansion when subjected to repeated cycles of heating and cooling. We develop a coarse-grained (micron-scale) interaction Hamiltonian for this system and perform molecular dynamics simulations, which quantitatively reproduce the experimentally observed irreversible growth. The functional form and values of the interaction parameters at the coarse-grained level are motivated by our knowledge at the atomic/molecular scale, and allows a simple way to incorporate the effect of polymeric binder. We demonstrate that irreversible growth happens only in the presence of intrinsic crystalline anisotropy of the powder material, is mediated by particles much smaller than the average crystallite size, and can be significantly reduced in the presence of high-strength polymeric binder with elevated glass transition temperatures.
Nucleon tensor charges and electric dipole moments
Pitschmann, Mario; Seng, Chien-Yeah; Roberts, Craig D.; Schmidt, Sebastian M.
2015-04-01
A symmetry-preserving Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to compute dressed-quark-core contributions to the nucleon σ -term and tensor charges. The latter enable one to directly determine the effect of dressed-quark electric dipole moments (EDMs) on neutron and proton EDMs. The presence of strong scalar and axial-vector diquark correlations within ground-state baryons is a prediction of this approach. These correlations are active participants in all scattering events and thereby modify the contribution of the singly represented valence quark relative to that of the doubly represented quark. Regarding the proton σ -term and that part of the proton mass which owes to explicit chiral symmetry breaking, with a realistic d -u mass splitting, the singly represented d quark contributes 37% more than the doubly represented u quark; and in connection with the proton's tensor charges, δTu , δTd , the ratio δTd /δTu is 18% larger than anticipated from simple quark models. Of particular note, the size of δTu is a sensitive measure of the strength of dynamical chiral symmetry breaking; and δTd measures the amount of axial-vector diquark correlation within the proton, vanishing if such correlations are absent.
Electric dipole moments of nanosolvated acid molecules in water clusters
Guggemos, Nicholas; Kresin, Vitaly V
2015-01-01
The electric dipole moments of $(H_{2}O)_{n}DCl$ ($n=3-9$) clusters have been measured by the beam deflection method. Reflecting the (dynamical) charge distribution within the system, the dipole moment contributes information about the microscopic structure of nanoscale solvation. The addition of a DCl molecule to a water cluster results in a strongly enhanced susceptibility. There is evidence for a noticeable rise in the dipole moment occurring at $n\\approx5-6$. This size is consistent with predictions for the onset of ionic dissociation. Additionally, a molecular dynamics model suggests that even with a nominally bound impurity an enhanced dipole moment can arise due to the thermal and zero point motion of the proton and the water molecules. The experimental measurements and the calculations draw attention to the importance of fluctuations in defining the polarity of water-based nanoclusters, and generally to the essential role played by motional effects in determining the response of fluxional nanoscale sy...
Which dipole are you studying in lab?
Binder, P.-M.; Tate, Reuben B.; Crowder, Callie K.
2017-01-01
We explore the similarities and differences between the electric dipole studied in introductory physics and the purportedly equivalent elementary experiment in which the electric potential is measured on a conductive sheet as a current flows. The former is a three-dimensional electrostatic dipole while the latter is a two-dimensional steady-state dipole. In spite of these differences, and as shown in this work, the potentials due to these dipoles look very similar. This may be misleading to either students or unaware instructors.
Lopez-Martens, A P; Khoo, T L; Korichi, A; Hannachi, F; Calderin, I J; Lauritsen, T; Ahmad, I; Carpenter, M P; Fischer, S M; Hackman, G; Janssens, R V F; Nisius, D; Reiter, P; Amro, H; Moore, E F
1999-01-01
The strength distribution of the primary gamma rays in the decay from superdeformed (SD) states is investigated by applying the maximum likelihood method. For the sup 1 sup 9 sup 4 Hg nucleus, 41 primary transitions are identified above 2600 keV. It is concluded that they represent the strongest 10% of the transitions selected stochastically from a Porter-Thomas distribution. This would support the scenario of a statistical decay of SD states via coupling to a compound state at normal deformation. However, the occurrence of several very strong 'one-step linking' transitions is found to have a very small probability. Based on the absence of strong primary transitions from SD states in adjacent nuclei, the situation in sup 1 sup 9 sup 4 Hg is viewed as a very lucky incidence.
Simplified approach to double jumps for fluorescing dipole-dipole interacting atoms
Hannstein, V; Hannstein, Volker; Hegerfeldt, Gerhard C.
2006-01-01
A simplified scheme for the investigation of cooperative effects in the quantum jump statistics of small numbers of fluorescing atoms and ions in a trap is presented. It allows the analytic treatment of three dipole-dipole interacting four-level systems which model the relevant level scheme of Ba+ ions. For the latter, a huge rate of double and triple jumps was reported in a former experiment and the huge rate was attributed to the dipole-dipole interaction. Our theoretical results show that the effect of the dipole-dipole interaction on these rates is at most 5% and that for the parameter values of the experiment there is practically no effect. Consequently it seems that the dipole-dipole interaction can be ruled out as a possible explanation for the huge rates reported in the experiment.
Lee, Won Hee; Lisanby, Sarah H.; Laine, Andrew F.; Peterchev, Angel V.
2017-01-01
Background This study examines the strength and spatial distribution of the electric field induced in the brain by electroconvulsive therapy (ECT) and magnetic seizure therapy (MST). Methods The electric field induced by standard (bilateral, right unilateral, and bifrontal) and experimental (focal electrically administered seizure therapy and frontomedial) ECT electrode configurations as well as a circular MST coil configuration was simulated in an anatomically realistic finite element model of the human head. Maps of the electric field strength relative to an estimated neural activation threshold were used to evaluate the stimulation strength and focality in specific brain regions of interest for these ECT and MST paradigms and various stimulus current amplitudes. Results The standard ECT configurations and current amplitude of 800–900 mA produced the strongest overall stimulation with median of 1.8–2.9 times neural activation threshold and more than 94% of the brain volume stimulated at suprathreshold level. All standard ECT electrode placements exposed the hippocampi to suprathreshold electric field, although there were differences across modalities with bilateral and right unilateral producing respectively the strongest and weakest hippocampal stimulation. MST stimulation is up to 9 times weaker compared to conventional ECT, resulting in direct activation of only 21% of the brain. Reducing the stimulus current amplitude can make ECT as focal as MST. Conclusions The relative differences in electric field strength may be a contributing factor for the cognitive sparing observed with right unilateral compared to bilateral ECT, and MST compared to right unilateral ECT. These simulations could help understand the mechanisms of seizure therapies and develop interventions with superior risk/benefit ratio. PMID:27318858
Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure
Zlobin, Alexander [Fermilab; Andreev, Nicolai [Fermilab; Barzi, Emanuela [Fermilab; Chlachidze, Guram [Fermilab; Kashikhin, Vadim [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Turrioni, Daniele [Fermilab; Karppinen, Mikko [CERN; Smekens, David [CERN
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.
Testing the Dipole and Quadrupole Moments of Galactic Models
Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.; Horack, John M.; Kouveliotou, Chryssa; Hartmann, Dieter H.; Hakkila, Jon
1996-01-01
If gamma-ray bursts originate in the Galaxy, at some level there should be a galactic pattern in their distribution on the sky. We test published galactic models by comparing their dipole and quadrupole moments with the moments of the BATSE 3B catalog. While many models have moments that are too large, several models are in acceptable or good agreement with the data.
Revisiting the phenomenology on the QCD color dipole picture
Lengyel, A I
2005-01-01
Using the QCD dipole picture of the hard BFKL Pomeron, we perform a 3 parameter fit analysis of the recent inclusive structure function experimental measurements at small-$x$ and intermediate $Q^2$. As a byproduct, the longitudinal structure function and the gluon distribution are predicted without further adjustments. The data description is quite reasonable, being timely a further study using resummed NLO BFKL kernels along the lines of recent theoretical developments.
Nabi, Jameel-Un
2011-02-01
This paper reports on the microscopic calculation of ground and excited states Gamow-Teller (GT) strength distributions, both in the electron capture and electron decay direction, for 54,55,56Fe. The associated electron and positron capture rates for these isotopes of iron are also calculated in stellar matter. These calculations were recently introduced and this paper is a follow-up which discusses in detail the GT strength distributions and stellar capture rates of key iron isotopes. The calculations are performed within the framework of the proton-neutron quasiparticle random phase approximation (pn-QRPA) theory. The pn-QRPA theory allows a microscopic state-by-state calculation of GT strength functions and stellar capture rates which greatly increases the reliability of the results. For the first time experimental deformation of nuclei are taken into account. In the core of massive stars isotopes of iron, 54,55,56Fe, are considered to be key players in decreasing the electron-to-baryon ratio ( Y e ) mainly via electron capture on these nuclide. The structure of the presupernova star is altered both by the changes in Y e and the entropy of the core material. Results are encouraging and are compared against measurements (where possible) and other calculations. The calculated electron capture rates are in overall good agreement with the shell model results. During the presupernova evolution of massive stars, from oxygen shell burning stages till around end of convective core silicon burning, the calculated electron capture rates on 54Fe are around three times bigger than the corresponding shell model rates. The calculated positron capture rates, however, are suppressed by two to five orders of magnitude.
Nabi, Jameel-Un; Sajjad, Muhammad
2007-11-01
Gamow-Teller (GT) strength transitions are an ideal probe for testing nuclear structure models. In addition to nuclear structure, GT transitions in nuclei directly affect the early phases of Type Ia and Type-II supernovae core collapse since the electron capture rates are partly determined by these GT transitions. In astrophysics, GT transitions provide an important input for model calculations and element formation during the explosive phase of a massive star at the end of its life-time. Recent nucleosynthesis calculations show that odd-odd and odd-A nuclei cause the largest contribution in the rate of change of lepton-to-baryon ratio. In the present manuscript, we have calculated the GT strength distributions and electron capture rates for odd-odd nucleus V50 by using the pn-QRPA theory. At present V50 is the first experimentally available odd-odd nucleus in fp-shell nuclei. We also compare our GT strength distribution with the recently measured results of a V50(d, He2)Ti50 experiment, with the earlier work of Fuller, Fowler, and Newman (referred to as FFN) and subsequently with the large-scale shell model calculations. One curious finding of the paper is that the Brink's hypothesis, usually employed in large-scale shell model calculations, is not a good approximation to use at least in the case of V50. SNe Ia model calculations performed using FFN rates result in overproduction of Ti50, and were brought to a much acceptable value by employing shell model results. It might be interesting to study how the composition of the ejecta using presently reported QRPA rates compare with the observed abundances.
Kurz, Ricardo; Cobo, Marcio Fernando; de Azevedo, Eduardo Ribeiro; Sommer, Michael; Wicklein, André; Thelakkat, Mukundan; Hempel, Günter; Saalwächter, Kay
2013-09-16
Carbon-proton dipole-dipole couplings between bonded atoms represent a popular probe of molecular dynamics in soft materials or biomolecules. Their site-resolved determination, for example, by using the popular DIPSHIFT experiment, can be challenged by spectral overlap with nonbonded carbon atoms. The problem can be solved by using very short cross-polarization (CP) contact times, however, the measured modulation curves then deviate strongly from the theoretically predicted shape, which is caused by the dependence of the CP efficiency on the orientation of the CH vector, leading to an anisotropic magnetization distribution even for isotropic samples. Herein, we present a detailed demonstration and explanation of this problem, as well as providing a solution. We combine DIPSHIFT experiments with the rotor-directed exchange of orientations (RODEO) method, and modifications of it, to redistribute the magnetization and obtain undistorted modulation curves. Our strategy is general in that it can also be applied to other types of experiments for heteronuclear dipole-dipole coupling determinations that rely on dipolar polarization transfer. It is demonstrated with perylene-bisimide-based organic semiconductor materials, as an example, in which measurements of dynamic order parameters reveal correlations of the molecular dynamics with the phase structure and functional properties.
Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Johansson, M.
1998-01-01
The dynamics of discrete two-dimensional nonlinear Schrodinger models with long-range dispersive interactions is investigated. In particular, we focus on the cases where the dispersion arises from a dipole-dipole interaction, assuming the dipole moments at each lattice site to be aligned either...
Low dipole moment large β electrooptic chromophores based on exocyclic double bond conjugated bridge
无
2001-01-01
Novel low dipole moment (μ) and large first hyperpolarizability (β) electrooptic chromophores have been designed based on the special characteristic of reversed dipole moment in the excited state of exocyclic double bond (ECDB) conjugated bridge by the optimization of the substituted method, and their electronic and second-order nonlinear optical properties have been theoretically investigated by employing the AM1/FF and ZINDO/S-CI approaches. By extending the conjugation length and optimizing the donor/acceptor strength, the oscillator strength of the excited transition that contributes to the molecular nonlinearity can be further enhanced. The designed chromophores possess a larger figure of merit (FOM) than that of D) ground state dipole moment.``
Excitation-energy dependence of the giant dipole resonance width
Enders, G.; Berg, F. D.; Hagel, K.; Kühn, W.; Metag, V.; Novotny, R.; Pfeiffer, M.; Schwalb, O.; Charity, R. J.; Gobbi, A.; Freifelder, R.; Henning, W.; Hildenbrand, K. D.; Holzmann, R.; Mayer, R. S.; Simon, R. S.; Wessels, J. P.; Casini, G.; Olmi, A.; Stefanini, A. A.
1992-07-01
High-energy γ rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of 136Xe+48Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width Γ is studied as a function of the fragment excitation energy E*. A saturation at about Γ=10 MeV is observed for E*/A>=1.0 MeV/nucleon.
Excitation-energy dependence of the giant dipole resonance width
Enders, G.; Berg, F.D.; Hagel, K.; Kuehn, W.; Metag, V.; Novotny, R.; Pfeiffer, M.; Schwalb, O. (II. Physikalisches Institut, Universitaet, Giessen, Giessen (Germany)); Charity, R.J.; Gobbi, A.; Freifelder, R.; Henning, W.; Hildenbrand, K.D.; Holzmann, R.; Mayer, R.S.; Simon, R.S.; Wessels, J.P. (Gesellschaft fuer Schwerionenforschung Darmstadt, Darmstadt (Germany)); Casini, G.; Olmi, A.; Stefanini, A.A. (Istituto Nazionale di Fisica Nucleare and University of Florence, Florence (Italy))
1992-07-13
High-energy {gamma} rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of {sup 136}Xe+{sup 48}Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width {Gamma} is studied as a function of the fragment excitation energy {ital E}{sup *}. A saturation at about {Gamma}=10 MeV is observed for {ital E}{sup *}/{ital A}{ge}1.0 MeV/nucleon.
He, S; Norgren, M
2000-02-01
The image solution for the static magnetic field outside a conducting sphere with an internal current dipole is considered. The image current, which is a linear distribution of magnetic dipoles on the line segment between the dipole point and the center of the sphere, is derived by using the fact that the induced current does not have any contribution to the radial component of the magnetic field outside the sphere. The image is then used to obtain some explicit formulas for identifying the location and tangential moment of the primary current dipole. This explicit identification method is also tested with a real model for a patient's brain.
Dipole Engineering for Conducting Polymers
McClain, William Edward
A method for the growth of a TiO2 adhesion layer on PEDOT:PSS (poly[3,4- ethylenedioxythiophene]: poly[styrenesulfonate]) and for further functionalization with self-assembled monolayers of phosphonates (SAMPs) was developed. The TiO2 adhesion layer was grown via chemical vapor deposition using a titanium(IV) t-butoxide precursor, and was characterized by goniometry and X-ray photoelectron spectroscopy. TiO 2 grown on a model system, H-terminated silicon, indicated that the surface was t-butoxide terminated. Phenylphosphonic acids were synthesized with a variety of molecular dipoles and were used to change the work function of PEDOT:PSS through the formation of an aggregate surface dipole. Good correlation was found between the z-component of the molecular dipole and the change in work function, indicating that the film was well-ordered and dense. The magnitude of the changes in work function and goniometry measurements were similar to measurements on ITO, a substrate on which phosphonates form well-ordered monolayers. As-grown PEDOT:PSS/TiO 2 electrodes showed a lower work function compared to PEDOT:PSS, which is attributed to residual t-butoxide groups on the TiO 2 surface. UPS measurements revealed that reductions in work function in the modified electrodes lowered the difference in energy between the Fermi energy (EF) of the conducting polymer and the LUMO of PCBM ([6,6]-phenyl-C 61-butyric acid methyl ester). A reduction of this energy difference should translate into increased electron injection in electron-only diodes; however, devices with modified electrodes showed decreased current densities. UPS/IPES measurements show that TiO2 grown using this method has a much larger band gap than bulk or nanocrystalline TiO2, which is likely responsible for this decrease in device currents. At high bias, device currents increase dramatically, and the effects of the phosphonates or t-butoxide terminated TiO2 vanish. This is attributed to a reduction of the TiO2 to
Two-component colour dipole emission in the central region of onium-onium scattering
Peschanski, R
1995-01-01
The initial-state radiation of soft colour dipoles produced in the central region of onium-onium scattering via single QCD Pomeron exchange (BFKL) is calculated in the framework of Mueller's dipole approach. The resulting dipole production has a two-component structure. One is constant with energy while the other grows and possesses a power-law tail at appreciably large transverse distances from the collision axis. It may be related to the growth of the gluon distribution at small Bjorken-x.
Electron Dipole-Dipole ESEEM in Field-Step ELDOR of Nitroxide Biradicals
Kulik, L. V.; Grishin, Yu. A.; Dzuba, S. A.; Grigoryev, I. A.; Klyatskaya, S. V.; Vasilevsky, S. F.; Tsvetkov, Yu. D.
2002-07-01
The use of a rapid stepping of the magnetic field for investigation of electron dipole-dipole ESEEM in pulsed X-band ELDOR is described. The magnetic field jump, synchronized with a microwave pumping pulse, is positioned between the second and the third pulses of the stimulated echo pulse sequence. This echo is measured as a function of the delay between the first and the second pulses. The data are analyzed for a Fourier transform resulting in a Pake resonance pattern. To remove the electron-nuclear contributions to ESEEM, time traces with pumping were divided by those without. This resulted in complete elimination of electron-nuclear contributions, which is seen from the absence of peaks at nuclear frequencies and the similarity of results for protonated and deuterated solvents. For increasing the electron-electron modulation depth, a scanning of the magnetic field during the microwave pumping is proposed. The interspin distances and their distribution are determined for two long-chained (ca. 2 nm) nitroxide biradicals in glassy toluene and in frozen nematic liquid crystal 4-cyano-4'-pentyl-biphenyl. For the latter solvent, the alignment of the axis connecting two nitroxides in biradicals is quantitatively analyzed.
Calculations of the dynamic dipole polarizabilities for the Li+ ion
Zhang, Yong-Hui; Tang, Li-Yan; Zhang, Xian-Zhou; Shi, Ting-Yun
2016-10-01
The B-spline configuration-interaction method is applied to the investigations of dynamic dipole polarizabilities for the four lowest triplet states (2 3S, 33S, 23P, and 33P) of the Li+ ion. The accurate energies for the triplet states of n 3S, n 3P, and n 3D, the dipole oscillator strengths for 23S(33S) → n 3P, 23P(33P) → n 3S, and 23P(33P) → n 3D transitions, with the main quantum number n up to 10 are tabulated for references. The dynamic dipole polarizabilities for the four triplet states under a wide range of photon energy are also listed, which provide input data for analyzing the Stark shift of the Li+ ion. Furthermore, the tune-out wavelengths in the range from 100 nm to 1.2 μm for the four triplet states, and the magic wavelengths in the range from 100 nm to 600 nm for the 23S → 33S, 23S → 23P, and 23S → 33P transitions are determined accurately for the experimental design of the Li+ ion. Project supported by the National Basic Research Program of China (Grant No. 2012CB821305) and the National Natural Science Foundation of China (Grant Nos. 11474319, 11274348, and 91536102).
Design, manufacture and measurements of permanent dipole magnets for DIRAC
Vorozhtsov, A; Kasaei, S; Solodko, E; Thonet, P A; Tommasini, D
2013-01-01
The one of the aim of the DIRAC experiment is the observation of the long-lived π+π- atoms, using the proton beam of the CERN Proton Synchrotron [1]. Two dipole magnets are needed for the for the DIRAC experiment as high resolution spectrometers. The dipole magnet will be used to identify the long-lived atoms on the high level background of π+π- pairs produced simultaneously with π+π- atoms. The proposed design is a permanent magnet dipole with a mechanical aperture of 60 mm. The magnet, of a total physical length of 66 mm, is based on Sm2Co17 blocks and provides an integrated field strength of 24·10-3 T×m. The Sm2Co17 was chosen as a material for the permanent magnet blocks due to its radiation hardness and weaker temperature dependence. The magnetic field quality is determined by 2 ferromagnetic poles, aligned together with the permanent magnets blocks. The paper describes the design, manufacture and magnetic measurements of the magnets.
Radiating dipoles in photonic crystals
Busch; Vats; John; Sanders
2000-09-01
The radiation dynamics of a dipole antenna embedded in a photonic crystal are modeled by an initially excited harmonic oscillator coupled to a non-Markovian bath of harmonic oscillators representing the colored electromagnetic vacuum within the crystal. Realistic coupling constants based on the natural modes of the photonic crystal, i.e., Bloch waves and their associated dispersion relation, are derived. For simple model systems, well-known results such as decay times and emission spectra are reproduced. This approach enables direct incorporation of realistic band structure computations into studies of radiative emission from atoms and molecules within photonic crystals. We therefore provide a predictive and interpretative tool for experiments in both the microwave and optical regimes.
Final Report: Levitated Dipole Experiment
Kesner, Jay [Massachusetts Institute of Technology, Cambridge, MA (United States); Mauel, Michael [Columbia Univ., New York, NY (United States)
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier et al., Physics of Plasmas, 13 (2006) 056111]. High- beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability made LDX the longest pulse fusion confinement experiment operating in the U.S. fusion program. A significant measure of progress in the LDX research program was the routine investigation of plasma confinement with a magnetically-levitated dipole and the resulting observations of confinement improvement. In both supported and levitated configurations, detailed measurements were made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma was created by multi frequency electron cyclotron resonance heating at 2.45 GHz, 6.4 GHz, 10.5 GHz and 28 GHz allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole was levitated or supported, the peak thermal electron temperature was estimated to exceed 500 eV and peak densities to approach 1e18 m^{-3}. We have found that levitation causes a strong inwards density pinch [Boxer et al., Nature Physics, 6 (2010) 207] and we have observed the central plasma density increase dramatically indicating a significant improvement in the confinement of a thermal plasma species.
Gravitational radiation from a rotating magnetic dipole
Hacyan, Shahen
2016-01-01
The gravitational radiation emitted by a rotating magnetic dipole is calculated. Formulas for the polarization amplitudes and the radiated power are obtained in closed forms, considering both the near and radiation zones of the dipole. For a neutron star, a comparison is made with other sources of gravitational and electromagnetic radiation.
Magnetic dipole oscillations and radiation damping
Stump, Daniel R.; Pollack, Gerald L.
1997-01-01
We consider the problem of radiation damping for a magnetic dipole oscillating in a magnetic field. An equation for the radiation reaction torque is derived, and the damping of the oscillations is described. Also discussed are runaway solutions for a rotating magnetic dipole moving under the influence of the reaction torque, with no external torque.
Electric dipoles on the Bloch sphere
Vutha, Amar C
2014-01-01
The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic & molecular physics.
Proton decay from the isoscalar giant dipole resonance in Ni-58
Hunyadi, M.; Hashimoto, H.; Li, T.; Akimune, H.; Fujimura, H.; Fujiwara, M.; Gacsi, Z.; Garg, U.; Hara, K.; Harakeh, M. N.; Hoffman, J.; Itoh, M.; Murakami, T.; Nakanishi, K.; Nayak, B. K.; Okumura, S.; Sakaguchi, H.; Terashima, S.; Uchida, M.; Yasuda, Y.; Yosoi, M.
2009-01-01
Proton decay from the 3 (h) over bar omega isoscalar giant dipole resonance (ISGDR) in Ni-58 has been measured using the (alpha, alpha' p) reaction at a bombarding energy of 386 MeV to investigate its decay properties. We have extracted the ISGDR strength under the coincidence condition between inel
Structure and decay properties of spin-dipole giant resonances within a semimicroscopical approach
Moukhai, EA; Rodin, VA; Urin, MH
1999-01-01
A semimicroscopical approach is applied to calculate: (i) strength functions for the charge-exchange spin-dipole giant resonances in the Pb-208 parent nucleus; (ii) partial and total branching ratios for the direct proton decay of the resonance in Bi-208. The approach is based on continuum-RPA calcu
Proton decay from the isoscalar giant dipole resonance in 58Ni
Hunyadi, M.; Hashimoto, H.; Li, T.; Akimune, H.; Fujimura, H.; Fujiwara, M.; Gacsi, Z.; Garg, U.; Hara, K.; Harakeh, M. N.; Hoffman, J.; Itoh, M.; Murakami, T.; Nakanishi, K.; Nayak, B. K.; Okumura, S.; Sakaguchi, H.; Terashima, S.; Uchida, M.; Yasuda, Y.; Yosoi, M.
2009-01-01
Proton decay from the 3 (h) over bar omega isoscalar giant dipole resonance (ISGDR) in Ni-58 has been measured using the (alpha, alpha' p) reaction at a bombarding energy of 386 MeV to investigate its decay properties. We have extracted the ISGDR strength under the coincidence condition between inel
Iwamoto, C.; Utsunomiya, H.; Tamii, A.; Akimune, H.; Nakada, H.; Shima, T.; Yamagata, T.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Shimbara, Y.; Nagashima, M.; Suzuki, T.; Fujita, H.; Sakuda, M.; Mori, T.; Izumi, T.; Okamoto, A.; Kondo, T.; Bilgier, B.; Kozer, H. C.; Lui, Y.-W.; Hatanaka, K.
2012-06-01
A high-resolution measurement of inelastic proton scattering off Zr90 near 0° was performed at 295 MeV with a focus on a pronounced strength previously reported in the low-energy tail of giant dipole resonance. A forest of fine structure was observed in the excitation energy region 7-12 MeV. A multipole decomposition analysis of the angular distribution for the forest was carried out using the ECIS95 distorted-wave Born approximation code with the Hartree-Fock plus random-phase approximation model of E1 and M1 transition densities and inclusion of E1 Coulomb excitation. The analysis separated pygmy dipole and M1 resonances in the forest at EPDR=9.15±0.18MeV with ΓPDR=2.91±0.64MeV and at EM1=9.53±0.06MeV with ΓM1=2.70±0.17MeV in the Lorentzian function, respectively. The B(E1)↑ value for pygmy dipole resonance over 7-11 MeV is 0.75±0.08e2fm2, which corresponds to 2.1±0.2% of the Thomas-Reiche-Kuhn sum rule.
Efimov effect for three interacting bosonic dipoles.
Wang, Yujun; D'Incao, J P; Greene, Chris H
2011-06-10
Three oriented bosonic dipoles are treated by using the hyperspherical adiabatic representation, providing numerical evidence that the Efimov effect persists near a two-dipole resonance and in a system where angular momentum is not conserved. Our results further show that the Efimov features in scattering observables become universal, with a known three-body parameter; i.e., the resonance energies depend only on the two-body physics, which also has implications for the universal spectrum of the four-dipole problem. Moreover, the Efimov states should be long-lived, which is favorable for their creation and manipulation in ultracold dipolar gases. Finally, deeply bound two-dipole states are shown to be relatively stable against collisions with a third dipole, owing to the emergence of a repulsive interaction originating in the angular momentum nonconservation for this system.
Multiscale dipole relaxation in dielectric materials
Hansen, Jesper Schmidt
2016-01-01
the cross coupling between the electric field fluctuations and dipole moment fluctuations can be ignored. The peak frequencies in the spectra of the autocorrelation functions are also derived. They depend on the wave vector squared which is a fingerprint of the underlying dipole diffusion mechanism....... For the longitudinal direction the simulation results show that the cross coupling between the electric field and the dipole moment is non-negligible compromising the theoretical predictions. The underlying mechanism for this coupling is not clear.......Dipole relaxation from thermally induced perturbations is investigated on different length scales for dielectric materials. From the continuum dynamical equations for the polarisation, expressions for the transverse and longitudinal dipole autocorrelation functions are derived in the limit where...
Pygmy dipole mode in deformed neutron-rich Mg isotopes close to the drip line
Yoshida, Kenichi
2009-10-01
We investigate the microscopic structure of the low-lying isovector-dipole excitation mode in neutron-rich Mg36,38,40 close to the drip line by means of the deformed quasiparticle random-phase approximation employing the Skyrme and the local pairing energy-density functionals. It is found that the low-lying bump structure above the neutron emission-threshold energy develops when the drip line is approached, and that the isovector dipole strength at ExThomas-Reiche-Kuhn dipole sum rule in Mg40. We obtained the collective dipole modes at around 8-10 MeV in Mg isotopes, that consist of many two-quasiparticle excitations of the neutron. The transition density clearly shows an oscillation of the neutron skin against the isoscalar core. We found significant coupling effects between the dipole and octupole excitation modes due to the nuclear deformation. It is also found that the responses for the compressional dipole and isoscalar octupole excitations are much enhanced in the lower energy region.
Analysis of Cylindrical Dipole Arrays for Smart Antenna Application
CAOXiangyu; GAOJun; K.M.Luk; LIANGChanghong
2005-01-01
A locally Conformal finite difference time domain (CFDTD) algorithm is studied and applied to model the radiation pattern of a linear dipole arrays mounted on a finite solid conducting cylinder. The numerical result shows that is in good agreement with the moment methods. Finally, the algorithm is applied to study smart antenna used in base station antenna. Several linear arrays mounted with uniform distribution on the cylinder are analyzed. The effects of the number of linear arrays on producing reasonably omnidirectional radiation pattern in the horizontal plane are investigated. It is shown that eight column dipole arrays may be a good choice for economical and practical considerations, and the omnidirection radiation characteristic can be better if the distance from the array axis to the cylinder surface is reduced.
Leading neutron production at HERA in the color dipole approach
Carvalho F.
2016-01-01
Full Text Available In this work we study leading neutron production in e + p → e + n + X collisions at high energies and calculate the Feynman xL distribution of these neutrons. The differential cross section is written in terms of the pion flux and of the photon-pion total cross section. We describe this process using the color dipole formalism and, assuming the validity of the additive quark model, we relate the dipole-pion with the well determined dipoleproton cross section. In this formalism we can estimate the impact of the QCD dynamics at high energies as well as the contribution of gluon saturation effects to leading neutron production. With the parameters constrained by other phenomenological information, we are able to reproduce the basic features of the recently released H1 leading neutron spectra.
Final Report: Levitated Dipole Experiment
Kesner, Jay; Mauel, Michael
2013-03-10
Since the very first experiments with the LDX, research progress was rapid and significant. Initial experiments were conducted with the high-field superconducting coil suspended by three thin rods. These experiments produced long-pulse, quasi-steady-state microwave discharges, lasting more than 10 s, having peak beta values of 20% [Garnier, Phys. Plasmas, v13, p. 056111, 2006]. High-beta, near steady-state discharges have been maintained in LDX for more than 20 seconds, and this capability makes LDX the longest pulse fusion confinement experiment now operating in the U.S. fusion program. In both supported and levitated configurations, detailed measurements are made of discharge evolution, plasma dynamics and instability, and the roles of gas fueling, microwave power deposition profiles, and plasma boundary shape. High-temperature plasma is created by multifrequency electron cyclotron resonance heating allowing control of heating profiles. Depending upon neutral fueling rates, the LDX discharges contain a fraction of energetic electrons, with mean energies above 50 keV. Depending on whether or not the superconducting dipole is levitated or supported, the peak thermal electron temperature is estimated to exceed 500 eV and peak densities reach 1.0E18 (1/m3). Several significant discoveries resulted from the routine investigation of plasma confinement with a magnetically-levitated dipole. For the first time, toroidal plasma with pressure approaching the pressure of the confining magnetic field was well-confined in steady-state without a toroidal magnetic field. Magnetic levitation proved to be reliable and is now routine. The dipole's cryostat allows up to three hours of "float time" between re-cooling with liquid helium and providing scientists unprecedented access to the physics of magnetizd plasma. Levitation eliminates field-aligned particle sources and sinks and results in a toroidal, magnetically-confined plasma where profiles are determined by cross
Teramae, Jun-nosuke
2016-06-01
Neurons in the cortical circuit continuous to generate irregular spike firing with extremely low firing rate (about 1-2 Hz) even when animals neither receive any external stimuli nor they do not show any significant motor movement. The ongoing activity is often called neuronal noise because measured spike trains are often highly irregular and also spike timings are highly asynchronous among neurons. Many experiments imply that neural networks themselves must generate the noisy activity as an intrinsic property of cortical circuit. However, how a network of neurons sustains the irregular spike firings with low firing rate remains unclear. Recently, by focusing on long-tailed distribution of amplitude of synaptic connections or EPSP (Excitatory Post-Synaptic Potential), we successfully revealed that due to coexistence of a few extremely strong synaptic connections and majority of weak synapses, nonlinear dynamics of population of spiking neurons can have a nontrivial stable state that corresponding to the intrinsic ongoing fluctuation of the cortical circuit. We also found that due to the fluctuation fidelity of spike transmission between neurons are optimized. Here, we report our recent findings of the ongoing fluctuation from viewpoints of mathematical and computational side.
Free induction decay caused by a dipole field
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.
Spectral distortions of the CMB dipole
Balashev, S A; Chluba, J; Ivanchik, A V; Varshalovich, D A
2015-01-01
We consider the distortions of the CMB dipole anisotropy related to the primordial recombination radiation (PRR) and primordial $y$- and $\\mu$-distortions. The signals arise due to our motion relative to the CMB restframe and appear as a frequency-dependent distortion of the CMB temperature dipole. To leading order, the expected relative distortion of CMB dipole does not depend on the particular observation directions and reaches the level of $10^{-6}$ for the PRR- and $\\mu$-distortions and $10^{-5}$ for the $y$-distortion in the frequency range 1 $-$ 700 GHz. The temperature differences arising from the dipole anisotropy of the relic CMB distortions depend on observation directions. For mutually opposite directions, collinear to the CMB dipole axis, the temperature differences because of the PRR- and $\\mu$-dipole anisotropy attain values $\\Delta T\\simeq 10\\,$nK in the considered range. The temperature difference arising from the $y$-dipole anisotropy may reach values up to $1\\,\\mu$K. The key features of the ...
Nonadiabatic Induced Dipole Moment by High Intensity Femtosecond Optical Pulses
Koprinkov, I. G.
2006-01-01
Nonadiabtic dressed states and nonadiabatic induced dipole moment in the leading order of nonadiabaticity is proposed. The nonadiabatic induced dipole moment is studied in the femtosecond time domain.
MAIER, R; KANELLAKOPULOS, B; APOSTOLIDIS, C; NUBER, B
1992-01-01
The dielectricity constant and the dipole moment of the 1:1 adducts of the tris(cyclopentadienyl)compounds of the trivalent lanthanoids La to Lu (with exception of the Pm compound) and of the lighter actinoids Th, U, Np, and Pu with tetrahydrofuran, (C5H5)3M(III).THF, were measured and the charge di
Testing the axial dipole hypothesis for the Moon by modeling the direction of crustal magnetization
Oliveira, J. S.; Wieczorek, M. A.
2017-02-01
Orbital magnetic field data show that portions of the Moon's crust are strongly magnetized, and paleomagnetic data of lunar samples suggest that Earth strength magnetic fields could have existed during the first several hundred million years of lunar history. The origin of the fields that magnetized the crust are not understood and could be the result of either a long-lived core-generated dynamo or transient fields associated with large impact events. Core dynamo models usually predict that the field would be predominantly dipolar, with the dipole axis aligned with the rotation axis. We test this hypothesis by modeling the direction of crustal magnetization using a global magnetic field model of the Moon derived from Lunar Prospector and Kaguya magnetometer data. We make use of a model that assumes that the crust is unidirectionally magnetized. The intensity of magnetization can vary with the crust, and the best fitting direction of magnetization is obtained from a nonnegative least squares inversion. From the best fitting magnetization direction we obtain the corresponding north magnetic pole predicted by an internal dipolar field. Some of the obtained paleopoles are associated with the current geographic poles, while other well-constrained anomalies have paleopoles at equatorial latitudes, preferentially at 90° east and west longitudes. One plausible hypothesis for this distribution of paleopoles is that the Moon possessed a long-lived dipolar field but that the dipole was not aligned with the rotation axis as a result of large-scale heat flow heterogeneities at the core-mantle boundary.
Effective restoration of dipole sum rules within the renormalized random-phase approximation
Hung, N. Quang; Dang, N. Dinh; Hao, T. V. Nhan; Phuc, L. Tan
2016-12-01
The dipole excitations for calcium and zirconium isotopes are studied within the fully self-consistent Hartree-Fock mean field incorporated with the renormalized random-phase approximation (RRPA) using the Skyrme interaction SLy5. The RRPA takes into account the effect of ground-state correlations beyond RPA owing to the Pauli principle between the particle-hole pairs that form the RPA excitations as well as the correlations due to the particle-particle and hole-hole transitions, whose effects are treated here in an effective way. By comparing the RPA results with the RRPA ones, which are obtained for isoscalar (IS) and isovector (IV) dipole excitations in 48,52,58Ca and 90,96,110Zr, it is shown that ground-state correlations beyond the RPA reduce the IS transition strengths. They also shift up the energy of the lowest IV dipole state and slightly push down the peak energy of the IV giant dipole resonance. As the result, the energy-weighted sums of strengths of both IS and IV modes decrease, causing the violation of the corresponding energy-weighted sum rules (EWSR). It is shown that this sum rule violation can be eliminated by taking into account the contribution of the particle-particle and hole-hole excitations together with the particle-hole ones in a simple and perturbative way. Consequently, the ratio of the energy-weighted sum of strengths of the pygmy dipole resonance to that of the giant dipole resonance increases.
Kemp, Daniel D; Gordon, Mark S
2008-06-05
The dipole moment of the gas phase water monomer is 1.85 D. When solvated in bulk water, the dipole moment of an individual water molecule is observed to be enhanced to the much larger value of 2.9 +/- 0.6 D. To understand the origin of this dipole moment enhancement, the effective fragment potential (EFP) method is used to solvate an ab initio water molecule to predict the dipole moments for various cluster sizes. The dipole moment as a function of cluster size, nH 2O, is investigated [for n = 6-20 (even n), 26, 32, 41, and 50]. Localized charge distributions are used in conjunction with localized molecular orbitals to interpret the dipole moment enhancement. These calculations suggest that the enhancement of the dipole moment originates from the decrease of the angle between the dipole vectors of the lone pairs on oxygen as the number of hydrogen bonds to that oxygen increases. Thus, the decreased angle, and the consequent increase in water dipole moment, is most likely to occur in environments with a larger number of hydrogen bonds, such as the center of a cluster of water molecules.
Formation number for vortex dipoles
Sadri, Vahid; Krueger, Paul S.
2016-11-01
This investigation considers the axisymmetric formation of two opposite sign concentric vortex rings from jet ejection between concentric cylinders. This arrangement is similar to planar flow in that the vortex rings will travel together when the gap between the cylinders is small, similar to a vortex dipole, but it has the advantage that the vortex motion is less constrained than the planar case (vortex stretching and vortex line curvature is allowed). The flow was simulated numerically at a jet Reynolds number of 1,000 (based on ΔR and the jet velocity), jet pulse length-to-gap ratio (L / ΔR) in the range 10-20, and gap-to-outer radius ratio (ΔR /Ro) in the range 0.01-0.1. Small gap ratios were chosen for comparison with 2D results. In contrast with 2D results, the closely paired vortices in this study exhibited pinch-off from the generating flow and finite formation numbers. The more complex flow evolution afforded by the axisymmetric model and its influence on the pinch-off process will be discussed. This material is based on work supported by the National Science Foundation under Grant No. 1133876 and SMU. This supports are gratefully acknowledged.
Superconducting Coil of Po Dipole
1983-01-01
The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam P0. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench.After this successful test up to its nominal field of 4.2 T, the power was not raised to reach a quench. The magnet was not installed in a beam and had no other further use. Nevertheless its construction provided knowledges and experience which became useful in the design and construction of the LHC magnets. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8211532X.
Collisional blockade in microscopic optical dipole traps.
Schlosser, N; Reymond, G; Grangier, P
2002-07-08
We analyze the operating regimes of a very small optical dipole trap, loaded from a magneto-optical trap, as a function of the atom loading rate, i.e., the number of atoms per second entering the dipole trap. We show that, when the dipole trap volume is small enough, a "collisional blockade" mechanism locks the average number of trapped atoms on the value 0.5 over a large range of loading rates. We also discuss the "weak loading" and "strong loading" regimes outside the blockade range, and we demonstrate experimentally the existence of these three regimes.
Chatzakis, Ioannis; Luo, Liang; Wang, Jigang; Shen, Nian Hai; Koschny, Thomas; Soukoulis, Costas
2011-03-01
Currently, there is strong interest to explore the dynamic control of the electromagnetic properties of metamaterials, which have important implications on their optoelectronic applications. While the design, fabrication and photo-doping of metamaterial/semiconductor structures have been actively pursued, some fundamental issues related to highly photo-excited states, their dynamic tuning and temporal evolution remain open. Using optical-pump terahertz probe spectroscopy, we report on the pump fluence dependence of the electric dipole resonance tunability in metamaterials. We find a previously undiscovered large non-monotonic variation on the strength of the dipole resonance peak with the photo-injected carrier concentration.
The dipole moment of the spin density as a local indicator for phase transitions
Schmitz, D.; Schmitz-Antoniak, C.; Warland, A.; Darbandi, M.; Haldar, S.; Bhandary, S.; Eriksson, O.; Sanyal, B.; Wende, H.
2014-07-01
The intra-atomic magnetic dipole moment - frequently called term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe2+ and Fe3+ sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry.
Analyses of a Dipole Antenna Loaded by a Cylindrical Shell of Double Negative (DNG Metamaterial
Khan M. Z. Shams
2007-01-01
Full Text Available The current distribution, input impedance, and radiation pattern of a cylindrical dipole antenna enclosed by a thin cylindrical shell of double negative (DNG metamaterial are computed using the piecewise sinusoidal Galerkin formulation. In the presence of the DNG shell, the dipole antenna exhibits three interesting characteristics. The input impedance shows potentials for wide bandwidth due to the relative insensitivity of the impedance with frequency. Within specific ranges of DNG material parameter values, the dipole shows resonance at much lower frequencies than its resonant frequency in free space. The dipole does not show change in the direction of the principal beam nor does it show signs of beam splitting and side lobes even when the antenna length approaches one and a half wavelength.
The dipole moment of the spin density as a local indicator for phase transitions.
Schmitz, D; Schmitz-Antoniak, C; Warland, A; Darbandi, M; Haldar, S; Bhandary, S; Eriksson, O; Sanyal, B; Wende, H
2014-07-21
The intra-atomic magnetic dipole moment - frequently called ⟨Tz⟩ term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe(2+) and Fe(3+) sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry.
Sharma, M. [Dept. of Physics and Astro-Physics, Univ. of Delhi (India); Govind, N.; Pratap, A. [Condense Matter Theory Group, National Physical Lab., New Delhi (India); Ajay; Tripathi, R.S. [Dept. of Physics, G.B. Pant Univ. of Agriculture and Technology, Pantnagar (India)
2001-07-01
In the present paper, we report the role of dipole-dipole interaction on the magnetic dynamics of single layer antiferromagnets. For this, the model Hamiltonian includes the exchange Heisenberg Hamiltonian as well as dipole-dipole interactions. Within the linear spin-wave theory, we employ the double time Green's function technique to obtain expressions for the spin wave dispersion, sublattice magnetization and the magnetic contribution to specific heat as a function of various parameters of the model Hamiltonian. We observe through numerical calculations that in the absence of anisotropy in exchange couplings the dipole-dipole interaction works as an anisotropy and sustains the magnetization even in a pure 2D system. (orig.)
Plasmonic functionalities based on detuned electrical dipoles
Pors, Anders Lambertus; Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.
2013-01-01
We introduce and demonstrate the concept of detuned electrical dipoles (DED) that originates from the plasmonic realization of the dressed-state picture of electromagnetically induced transparency in atomic physics. Numerically and experimentally analyzing DED metamaterials consisting of unit cells...
Plasmonic functionalities based on detuned electrical dipoles
Pors, Anders Lambertus; Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.
2013-01-01
We introduce and demonstrate the concept of detuned electrical dipoles (DED) that originates from the plasmonic realization of the dressed-state picture of electromagnetically induced transparency in atomic physics. Numerically and experimentally analyzing DED metamaterials consisting of unit cells...
Population Dynamics in Cold Gases Resulting from the Long-Range Dipole-Dipole Interaction
Mandilara, A; Pillet, P
2009-01-01
We consider the effect of the long range dipole-dipole interaction on the excitation exchange dynamics of cold two-level atomic gase in the conditions where the size of the atomic cloud is large as compared to the wavelength of the dipole transition. We show that this interaction results in population redistribution across the atomic cloud and in specific spectra of the spontaneous photons emitted at different angles with respect to the direction of atomic polarization.
Cosmological CMBR dipole in open universes?
Langlois, D
1997-01-01
The observed CMBR dipole is generally interpreted as a Doppler effect arising from the motion of the Earth relative to the CMBR frame. An alternative interpretation, proposed in the last years, is that the dipole results from ultra-large scale isocurvature perturbations. We examine this idea in the context of open cosmologies and show that the isocurvature interpretation is not valid in an open universe, unless it is extremely close to a flat universe, $|\\Omega_0 -1|< 10^{-4}$.
On the dipole moment of CO/+/.
Certain, P. R.; Woods, R. C.
1973-01-01
Results of self-consistent field calculations on neutral CO, its positive ion, and on neutral CN to verify an earlier estimate of the dipole moment of CO(+) in its ground super 2 Sigma state. Based on the above-mentioned calculations, direct evidence is obtained that the dipole moment (relative to the center of mass) is approximately 2.5 plus or minus 0.5 C, as previously determined by Kopelman and Klemperer (1962).
An apparent paradox concerning the field of an ideal dipole
Parker, Edward
2017-03-01
The electric or magnetic field of an ideal dipole is known to have a Dirac delta function at the origin. The usual textbook derivation of this delta function is rather ad hoc and cannot be used to calculate the delta-function structure for higher multipole moments. Moreover, a naive application of Gauss’s law to the ideal dipole field appears to give an incorrect expression for the dipole’s effective charge density. We derive a general result for the delta-function structure at the origin of an arbitrary ideal multipole field without using any advanced techniques from distribution theory. We find that the divergence of a singular vector field can contain a derivative of a Dirac delta function even if the field itself does not contain a delta function. We also argue that a physical interpretation of the delta function in the dipole field previously given in the literature is perhaps misleading and may require clarification. Both the explanation of and the resolution to this ‘paradox’ should be accessible to someone who has taken a graduate- or advanced undergraduate-level course in classical electrodynamics.
Ringbom, A; Conde, H; Elmgren, K; Olsson, N; Rahm, J; Rönnqvist, T; Jonsson, O; Nilsson, L; Renberg, P U; Tibell, G; Bargholtz, C; Fransson, K; Lindh, K; Tegnér, P E; Thörngren-Engblom, P; Van der Werf, S Y
2001-01-01
Double-differential cross sections of the sup 1 sup 0 sup , sup 1 sup 1 B(n, p) sup 1 sup 0 sup , sup 1 sup 1 Be reactions have been measured at 96 MeV in the angular range 0 deg. -30 deg. for excitation energies up to 35 MeV. The spectra have been decomposed into different multipolarities using sample angular distributions calculated within the distorted-wave Born approximation. From the identified Gamow-Teller strength, S subbeta sub sup + values were obtained for sup 1 sup 0 B and sup 1 sup 1 B. At higher excitation energies, the spectra are dominated by L=1 strength in broad distributions with maxima around 22 and 12 MeV in sup 1 sup 0 B and sup 1 sup 1 B, respectively.
Dynamic Dipole-Dipole Interactions between Excitons in Quantum Dots of Different Sizes
Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng
2005-01-01
Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes.......Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes....
Intrinsic Decoherence of a Two-Atom System with Dipole-Dipole Interaction
QI Lin-Na; ZHU Ai-Dong; ZHANG Shou
2008-01-01
@@ We investigate the effect of dipole-dipole interaction on the intrinsic decoherence of a system which consists of two two-level atoms and an optical cavity. The entanglement of the system is calculated by making use of concurrence. Our results show that the appropriate choice for the coupling constant Ω of dipole-dipole interaction can restrain the intrinsic decoherence of the system. We also find a special phenomenon. No matter what the value of γ is, the concurrence of system slowly increases and cannot exceed 0.71 when Ω= 1.
Dynamic Dipole-Dipole Interactions between Excitons in Quantum Dots of Different Sizes
Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng;
2005-01-01
Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes.......Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes....
Dipole-moment-driven cooperative supramolecular polymerization.
Kulkarni, Chidambar; Bejagam, Karteek K; Senanayak, Satyaprasad P; Narayan, K S; Balasubramanian, S; George, Subi J
2015-03-25
While the mechanism of self-assembly of π-conjugated molecules has been well studied to gain control over the structure and functionality of supramolecular polymers, the intermolecular interactions underpinning it are poorly understood. Here, we study the mechanism of self-assembly of perylene bisimide derivatives possessing dipolar carbonate groups as linkers. It was observed that the combination of carbonate linkers and cholesterol/dihydrocholesterol self-assembling moieties led to a cooperative mechanism of self-assembly. Atomistic molecular dynamics simulations of an assembly in explicit solvent strongly suggest that the dipole-dipole interaction between the carbonate groups imparts a macro-dipolar character to the assembly. This is confirmed experimentally through the observation of a significant polarization in the bulk phase for molecules following a cooperative mechanism. The cooperativity is attributed to the presence of dipole-dipole interaction in the assembly. Thus, anisotropic long-range intermolecular interactions such as dipole-dipole interaction can serve as a way to obtain cooperative self-assembly and aid in rationalizing and predicting the mechanisms in various synthetic supramolecular polymers.
Stephenson, R. A.; Ershov, A.
2001-12-01
One way in which theoretical rheological models of the lithosphere can be constrained by geological data is through estimations of the lithosphere's integrated strength. When an applied force exceeds this, then the lithosphere should lose its integrity and undergo irreversible deformation (WLF - "whole lithosphere failure"). The geological expression of this kind of deformational regime is the development of rifts (in extension) and inverted structures (in compression). By considering intracratonic structures rather than marginal ones it is possible to exclude additional extraneous influences and infer the net effect of intraplate stresses. Here, actual intraplate structures are considered in terms of a rheological model in which the non-brittle part of the lithosphere deforms viscously (by creep) in response to applied forces. This is in contrast to conventional estimations of total lithosphere strength based on "yield stress envelopes" in which "ductile" deformation is taken to be time-invariant (plastic). Taking into account the implications of adopting a viscous rheology in place of a plastic one in evaluating the "strength" of the lithosphere, it is necessary to incorporate the time-dependence of stresses, strains and strain rates and also the dependence of the bulk strain rate on the total applied force. This means that the duration of loading of tectonic forces prior to eventual rifting or inversion is also an important model variable. The mechanism that controls strain rate and stress distribution in the lithosphere prior to WLF in the model is one of stress redistribution from ductile deformation zones into elastic ones, as determined by stress relaxation in the former and stress amplification in the latter given an assumed constant applied boundary force. A stable equilibrium regime of deformation occurs when, at each point within the lithosphere, the stress reduction effected by viscous relaxation equals the stress increase effected by the applied force
Spin dipole nuclear matrix elements for double beta decay nuclei by charge-exchange reactions
Ejiri, H
2016-01-01
Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (3He,t) charge exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) for low-lying 2- states were derived from the experimental SD strengths by referring to the experimental GT (Gamow-Teller) and F (Fermi) strengths. They are consistent with the empirical SD NMEs based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.
Coupled-Channel Models of Direct-Semidirect Capture via Giant-Dipole Resonances
Thompson, I J [Lawrence Livermore National Laboratory (LLNL); Escher, Jutta E [ORNL; Arbanas, Goran [ORNL
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.
First principles description of the giant dipole resonance in 16O
Bacca, Sonia; Hagen, Gaute; Orlandini, Giuseppina; Papenbrock, Thomas
2013-01-01
We present an ab-initio calculation of the giant dipole resonance in 16O based on a nucleon-nucleon (NN) interaction from chiral effective field theory that reproduces NN scattering data with high accuracy. By merging the Lorentz integral transform and the coupled-cluster methods, we extend the previous theoretical limits for break-up observables in light nuclei with mass numbers (A<=7), and address the collective giant dipole resonance of 16O. We successfully benchmark the new approach against virtually exact results from the hyper-spherical harmonics method in 4He. Our results for 16O reproduce the position and the total strength (bremsstrahlung sum rule) of the dipole response very well. When compared to the cross section from photo-absorption experiments the theoretical curve exhibits a smeared form of the peak. The tail region between 40 and 100 MeV is reproduced within uncertainties.
S. Bagchi
2015-12-01
Full Text Available The Isoscalar Giant Monopole Resonance (ISGMR and the Isoscalar Giant Dipole Resonance (ISGDR compression modes have been studied in the doubly-magic unstable nucleus 56Ni. They were measured by inelastic α-particle scattering in inverse kinematics at 50 MeV/u with the MAYA active target at the GANIL facility. The centroid of the ISGMR has been obtained at Ex=19.1±0.5 MeV. Evidence for the low-lying part of the ISGDR has been found at Ex=17.4±0.7 MeV. The strength distribution for the dipole mode shows similarity with the prediction from the Hartree–Fock (HF based random-phase approximation (RPA [1]. These measurements confirm inelastic α-particle scattering as a suitable probe for exciting the ISGMR and the ISGDR modes in radioactive isotopes in inverse kinematics.
Localization technique research of a pipeline robot based on the magnetic-dipole model
Junyuan LI; Hongjun CHEN; Shengfeng LI; Xiaohua ZHANG
2008-01-01
The magnetic field distribution of an emission antenna is studied in this paper. When the slenderness ratio of the emission antenna is high, the emission antenna can be simplified as a magnetic dipole for practical application. The numerical results of the magnetic dipole magnetic field show that the magnetic magnitude dis-tribution has a hump-shape, whose direction is perpendi-cular with the antenna axis direction. A localization method based on the hump-shape signal detection is presented. The experimental result shows that the preci-sion can reach a value of + 5 cm. The method can be used to localize a pipeline robot working in a metal pipe.
Nguyen, Thanh Long; Celistrino Teixeira, Raul; Hermann Avigliano, Carla; Cantat Moltrecht, Tigrane; Raimond, Jean Michel; Haroche, Serge; Gleyzes, Sebastiens; Brune, Michel
2016-05-01
Dipole-dipole interactions between Rydberg atoms are a flourishing tool for quantum information processing and for quantum simulation of complex many-body problems. Microwave spectroscopy of a dense Rydberg gas trapped close to a superconducting atom chip in the strong dipole blockade regime reveals directly the many-body atomic interaction spectrum. We present here a direct measurement of the interaction energy distribution in the strong dipole blockade regime, based on microwave spectroscopy. We first apply this method to the observation of the excitation dynamics of the Rydberg gas, conditioned by dipole-dipole interactions, in either the strong blockade regime or the so-called facilitation regime. We also observe with this method the atomic cloud expansion driven by the repulsive Van der Waals interaction after excitation. This measurement, in good agreement with Monte Carlo simulations of the excitation process and of the cloud dynamics, reveals the limits of the frozen gas approximation. This method can help investigate self-organization and dynamical phase transitions in Rydberg-atom based quantum simulators. This study thus opens a promising route for quantum simulation of many-body systems and quantum information transport in chains of strongly interacting Rydberg atom.
Breakdown of the Dipole Approximation in Strong-Field Ionization
Ludwig, A; Mayer, B W; Phillips, C R; Gallmann, L; Keller, U
2014-01-01
We report the breakdown of the electric dipole approximation in the long-wavelength limit in strong-field ionization with linearly polarized few-cycle mid-infrared laser pulses at intensities on the order of 10$^{13}$ W/cm$^2$. Photoelectron momentum distributions were recorded by velocity map imaging and projected onto the beam propagation axis. We observe an increasing shift of the peak of this projection opposite to the beam propagation direction with increasing laser intensities. From a comparison with semi-classical simulations, we identify the combined action of the magnetic field of the laser pulse and the Coulomb potential as origin of our observations.
rp Drell-Yan Process in Color Dipole Model
ZHAO Hong-Ming; DUAN Chun-Gui
2002-01-01
We study pion-proton Orp) Drell-Yan (DY) dilepton production in the target rest frame with color dipole model. The prediction for πp DY cross section at the energies of RHIC and LHC is presented, and it can be compared with the data directly, because it does not need K factor. At the same time, the transverse momentum distribution is shown in quantities, which is not available from the standard parton model. The experimental studies of the process could test the color model for DY dilepton production.
Hard jet probes in terms of colorless QCD dipoles
Peschanski, R
2000-01-01
the forward jet playing the role of a hard probe is analyzed in terms of QCD dipole (color-singlet q\\bar q) configurations in the transverse position space. There are sizable differences with the analogous q\\bar q configurations of a hard photon which may lead to significant phenomenological consequences on the analysis of hard processes using a forward jet probe, e.g. at the Tevatron. A geometrical interpretation of the resulting distribution in terms of black disk diffraction is proposed.
Elementary quantum mechanics of the neutron with an electric dipole moment.
Baym, Gordon; Beck, D H
2016-07-05
The neutron, in addition to possibly having a permanent electric dipole moment as a consequence of violation of time-reversal invariance, develops an induced electric dipole moment in the presence of an external electric field. We present here a unified nonrelativistic description of these two phenomena, in which the dipole moment operator, [Formula: see text], is not constrained to lie along the spin operator. Although the expectation value of [Formula: see text] in the neutron is less than [Formula: see text] of the neutron radius, [Formula: see text], the expectation value of [Formula: see text] is of order [Formula: see text] We determine the spin motion in external electric and magnetic fields, as used in past and future searches for a permanent dipole moment, and show that the neutron electric polarizability, although entering the neutron energy in an external electric field, does not affect the spin motion. In a simple nonrelativistic model we show that the expectation value of the permanent dipole is, to lowest order, proportional to the product of the time-reversal-violating coupling strength and the electric polarizability of the neutron.
Dynamic dipole-dipole interactions between excitons in quantum dots of different sizes
Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng;
2004-01-01
A model of the resonance dynamic dipole-dipole interaction between excitons confined in quantum dots (QDs) of different sizes at close enough distance is given in terms of parity inheritance and exchange of virtual photons. Microphotoluminescence spectra of GaAs-AlGaAs coupled QDs are proposed to...
Tulintseff, A. N.
1993-01-01
Printed dipole elements and their complement, linear slots, are elementary radiators that have found use in low-profile antenna arrays. Low-profile antenna arrays, in addition to their small size and low weight characteristics, offer the potential advantage of low-cost, high-volume production with easy integration with active integrated circuit components. The design of such arrays requires that the radiation and impedance characteristics of the radiating elements be known. The FDTD (Finite-Difference Time-Domain) method is a general, straight-forward implementation of Maxwell's equations and offers a relatively simple way of analyzing both printed dipole and slot elements. Investigated in this work is the application of the FDTD method to the analysis of printed dipole and slot elements transversely coupled to an infinite transmission line in a multilayered configuration. Such dipole and slot elements may be used in dipole and slot series-fed-type linear arrays, where element offsets and interelement line lengths are used to obtain the desired amplitude distribution and beam direction, respectively. The design of such arrays is achieved using transmission line theory with equivalent circuit models for the radiating elements. In an equivalent circuit model, the dipole represents a shunt impedance to the transmission line, where the impedance is a function of dipole offset, length, and width. Similarly, the slot represents a series impedance to the transmission line. The FDTD method is applied to single dipole and slot elements transversely coupled to an infinite microstrip line using a fixed rectangular grid with Mur's second order absorbing boundary conditions. Frequency-dependent circuit and scattering parameters are obtained by saving desired time-domain quantities and using the Fourier transform. A Gaussian pulse excitation is applied to the microstrip transmission line, where the resulting reflected signal due to the presence of the radiating element is used
Berrig, O E; Jones, R; Koopman, J; Koutchouk, Jean-Pierre; Schmickler, Hermann; Schmidt, F
2001-01-01
The so-called "AC-Dipole" principle allows the excitation of transverse oscillations to large (several sigma) excursions without emittance blow-up. The idea was originally proposed and tested at BNL for resonance crossing with polarized beams, using an orbit corrector dipole with an excitation frequency close to the betatron tune, hence "AC-Dipole". This method of beam excitation has several potential applications in teh LHC, such as phase advance and beta-measurements, dynamic aperture studies and the investigation of resonance strengths. The technique was recently tested in the CERN SPS using the transverse damper as an "AC-Dipole" providing the fixed frequency excitation. Results from this experiment are presented, along with an explanation of the underlying principle.
Hou, X. N.; Liu, Y. H.; Huang, F.; Jiang, S. Z.; Chen, Z. Y.; Zhang, R. Y.
2016-09-01
Effects of radial electric field on the structures and dynamics of dust dipoles are studied by molecular dynamics simulations. The dipoles' configuration and mean distance to the system center are used to illustrate the structures of the whole system. It is shown that the dipole particles can arrange themselves into ring-like structures in the absence of external electric field, which can gradually transform to vortex, and then to radial arrangement with the increase of the strength of electric field. The trajectories, mean square displacement, and the mean speed in radial and tangential directions of dipoles are investigated to depict the effects of the radial electric filed on the collective motion of dust dipolar particles, which are closely associated with the growth of dust particle, especially for the formation of rod-like and some other complex fractal dust particles.
Artificial abelian gauge potentials induced by dipole-dipole interactions between Rydberg atoms
Cesa, A
2013-01-01
We analyze the influence of dipole-dipole interactions between Rydberg atoms on the generation of abelian artificial gauge potentials and fields. When two Rydberg atoms are driven by a uniform laser field, we show that the combined atom-atom and atom-field interactions give rise to new, non-uniform, artificial gauge potentials. We identify the mechanism responsible for the emergence of these gauge potentials. Analytical expressions for the latter indicate that the strongest artificial magnetic fields are reached in the regime intermediate between the dipole blockade regime and the regime in which the atoms are sufficiently far apart such that atom-light interaction dominates over atom-atom interactions. We discuss the differences and similarities of artificial gauge fields originating from resonant dipole-dipole and van der Waals interactions. We also give an estimation of experimentally attainable artificial magnetic fields resulting from this mechanism.
Kanada-En'yo, Yoshiko
2016-02-01
Isovector and isoscalar dipole excitations in 9Be and 10Be are investigated in the framework of antisymmetrized molecular dynamics, in which angular-momentum and parity projections are performed. In the present method, 1p-1h excitation modes built on the ground state and a large amplitude α -cluster mode are taken into account. The isovector giant dipole resonance (GDR) in E >20 MeV shows the two-peak structure, which is understood from the dipole excitation in the 2 α core part with the prolate deformation. Because of valence neutron modes against the 2 α core, low-energy E 1 resonances appear in E Thomas-Reiche-Kuhn sum rule and 10 % of the calculated energy-weighted sum. The dipole resonance at E ˜15 MeV in 10Be can be interpreted as the parity partner of the ground state having a 6He+α structure and has remarkable E 1 strength because of the coherent contribution of two valence neutrons. The isoscalar dipole strength for some low-energy resonances is significantly enhanced by the coupling with the α -cluster mode. For the E 1 strength of 9Be, the calculation overestimates the energy-weighted sum (EWS) in the low-energy (E <20 MeV) and GDR (20
Axion Induced Oscillating Electric Dipole Moment of the Electron
Hill, Christopher T
2016-01-01
The axion electromagnetic anomaly induces an oscillating electric dipole for the electron of frequency $m_a$ and strength $\\sim 10^{-32}$ e-cm, two orders of magnitude above the nucleon, and within four orders of magnitude of the present standard model constant limit. We give a detailed study of this phenomenon via the interaction of the cosmic axion, through the electromagnetic anomaly, with particular emphasis on the decoupling limit of the axion, $\\partial_t a(t)\\propto m_a \\rightarrow 0$. The general form of the action involves a local contact interaction and a nonlocal contribution that enforces the decoupling limit. We derive the effective action in the Pauli-Schroedinger non-relativistic formalism, and in Georgi's heavy quark formalism adapted to the "heavy electron" (heavy compared to $m_a$). We compute the electric dipole radiation emitted by stationary electrons, and we discuss a number of experimental configurations that may yield detectable signals. Phased array radiators with $N^2$ unit cell magn...
LHC dipoles: the countdown has begun
Patrice Loiez
2002-01-01
At the entrance to the fourth floor corridor of the LHC-MMS (Main Magnets and Superconductors) Group in building 30, the Director-General has unveiled an electronic information panel indicating the number of LHC dipoles still to be delivered and the days remaining to the deadline (30 June 2006). The panel was the idea of Lucio Rossi, leader of the MMS Group, which is responsible for the construction of the dipole magnets. The unveiling ceremony took place on the morning of Friday 11 October 2002, at the end of a drink held to celebrate with MMS group and the LHC top management the exceptional performance of the latest dipoles, built by the French consortium Alstom-Jeumont. They are the first dipoles to achieve a magnetic field of 9 tesla in one go without quenching, thus exceeding the nominal operating field of 8.3 tesla. The challenge is now to increase the production rate from 2 to 35 dipoles per month by 2004 in order to meet the deadline, while maintaining this quality. Photo 01: The Director-General Luci...
Effective restoration of dipole sum rules within the renormalized random-phase approximation
Hung, N Quang; Hao, T V Nhan; Phuc, L Tan
2016-01-01
The dipole excitations for calcium and zirconium isotopes are studied within the fully self-consistent Hartree-Fock mean field incorporated with the renormalized random-phase approximation (RRPA) using the Skyrme interaction SLy5. The RRPA takes into account the effect of ground-state correlations beyond RPA owing to the Pauli principle between the particle-hole pairs that form the RPA excitations as well as the correlations due to the particle-particle and hole-hole transitions, whose effects are treated here in an effective way. By comparing the RPA results with the RRPA ones, which are obtained for isoscalar (IS) and isovector (IV) dipole excitations in $^{48, 52, 58}$Ca and $^{90, 96, 110}$Zr, it is shown that ground-state correlations beyond the RPA reduce the IS transition strengths. They also shift up the energy of the lowest IV dipole state and slightly push down the peak energy of the IV giant dipole resonance. As the result, the energy-weighted sums of strengths of both IS and IV modes decrease, cau...
Alday, Luis F. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)]. E-mail: l.f.alday@phys.uu.nl; Boer, Jan de [Instituut voor Theoretische Fysica, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)]. E-mail: jdeboer@science.uva.nl; Messamah, Ilies [Instituut voor Theoretische Fysica, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)]. E-mail: imessama@science.uva.nl
2006-07-03
We study gravitational solutions that admit a dual CFT description and carry non-zero dipole charge. We focus on the black ring solution in AdS{sub 3}xS{sup 3} and extract from it the one-point functions of all CFT operators dual to scalar excitations of the six-dimensional metric. In the case of small black rings, characterized by the level N, angular momentum J and dipole charge q{sub 3}, we show how the large N and J dependence of the one-point functions can be reproduced, under certain assumptions, directly from a suitable ensemble in the dual CFT. Finally we present a simple toy model that describes the thermodynamics of the small black ring for arbitrary values of the dipole charge.
Theory of Dipole Induced Electromagnetic Transparency
Puthumpally-Joseph, Raiju; Sukharev, Maxim; Charron, Eric
2015-01-01
A detailed theory describing linear optics of vapors comprised of interacting multi-level quantum emitters is proposed. It is shown both by direct integration of Maxwell-Bloch equations and using a simple analytical model that at large densities narrow transparency windows appear in otherwise completely opaque spectra. The existence of such windows is attributed to overlapping resonances. This effect, first introduced for three-level systems in [R. Puthumpally-Joseph, M. Sukharev, O. Atabek and E. Charron, Phys. Rev. Lett. 113, 163603 (2014)], is due to strongly enhanced dipole-dipole interactions at high emitters' densities. The presented theory extends this effect to the case of multilevel systems. The theory is applied to the D1 transitions of interacting Rb-85 atoms. It is shown that at high atomic densities, Rb-85 atoms can behave as three-level emitters exhibiting all the properties of dipole induced electromagnetic transparency. Applications including slow light and laser pulse shaping are also propose...
Dipole hearing measurements in elasmobranch fishes.
Casper, Brandon M; Mann, David A
2007-01-01
The hearing thresholds of the horn shark Heterodontus francisci and the white-spotted bamboo shark Chiloscyllium plagiosum were measured using auditory evoked potentials (AEP) in response to a dipole sound stimulus. The audiograms were similar between the two species with lower frequencies yielding lower particle acceleration thresholds. The particle acceleration audiograms showed more sensitive hearing at low frequencies than previous elasmobranch audiograms, except for the lemon shark Negaprion brevirsotris. Auditory evoked potential signals were also recorded while the dipole stimulus was moved to different locations above the head and body. The strongest AEP signals were recorded from the area around the parietal fossa, supporting previous experiments that suggested this region is important for elasmobranch hearing. This is the first time that hearing experiments have been conducted using a dipole stimulus with elasmobranchs, which more closely mimics the natural sounds of swimming prey.
Alday, L F; Messamah, I; Alday, Luis F.; Boer, Jan de; Messamah, Ilies
2006-01-01
We study gravitational solutions that admit a dual CFT description and carry non zero dipole charge. We focus on the black ring solution in AdS_3 x S^3 and extract from it the one-point functions of all CFT operators dual to scalar excitations of the six-dimensional metric. In the case of small black rings, characterized by the level N, angular momentum J and dipole charge q_3, we show how the large N and J dependence of the one-point functions can be reproduced, under certain assumptions, directly from a suitable ensemble in the dual CFT. Finally we present a simple toy model that describes the thermodynamics of the small black ring for arbitrary values of the dipole charge.
Pursuit and Synchronization in Hydrodynamic Dipoles
Kanso, Eva
2015-01-01
We study theoretically the behavior of a class of hydrodynamic dipoles. This study is motivated by recent experiments on synthetic and biological swimmers in microfluidic \\textit{Hele-Shaw} type geometries. Under such confinement, a swimmer's hydrodynamic signature is that of a potential source dipole, and the long-range interactions among swimmers are obtained from the superposition of dipole singularities. Here, we recall the equations governing the positions and orientations of interacting asymmetric swimmers in doubly-periodic domains, and focus on the dynamics of swimmer pairs. We obtain two families of `relative equilibria'-type solutions that correspond to pursuit and synchronization of the two swimmers, respectively. Interestingly, the pursuit mode is stable for large tail swimmers whereas the synchronization mode is stable for large head swimmers. These results have profound implications on the collective behavior reported in several recent studies on populations of confined microswimmers.
Electric-dipole sum rule in nuclear matter
Fabrocini, A.; Fantoni, S.
1985-03-01
The enhancement factor K in the electric-dipole sum rule for some realistic models of symmetrical nuclear matter is calculated using variational theory. The nuclear-matter wave function used contains central, spin, isospin, tensor and spin-orbit pair correlations. The non-central correlations, particularly the tensor one, give the major contribution to K. At experimental equilibrium density K. turns out to be ≈ 1.8, of which 65% comes from OPEP and 30% from the short-range part of the interaction. The two-pion-exchange three-nucleon interaction contributes ≈ 0.2% and is cancelled, to a large extent, by the contribution due to the intermediate-range two-body potential. The relationship of the summed oscillator strength with the effective mass is also discussed.
Cooperative Ordering in Lattices of Interacting Dipoles
Bettles, Robert J; Adams, Charles S
2014-01-01
Using classical electrodynamics simulations we investigate the cooperative behavior of regular monolayers of induced two-level dipoles, including their cooperative decays and shifts. For the particular case of the kagome lattice we observe behavior akin to EIT for lattice spacings less than the probe wavelength. Within this region the dipoles exhibit ferroelectric and anti-ferroelectric ordering. We also model how the cooperative response is manifested in the optical transmission through the kagome lattice, with sharp changes in transmission from 10% to 80% for small changes in lattice spacing.
Complete electric dipole response in 208Pb
Tamii, A; von Neumann-Cosel, P; Fujita, Y; Adachi, T; Bertulani, C A; Carter, J; Dozono, M; Fujita, H; Fujita, K; Hatanaka, K; Heilmann, A M; Ishikawa, D; Itoh, M; Ong, H J; Kawabata, T; Kalmykov, Y; Litvinova, E; Matsubara, H; Nakanishi, K; Neveling, R; Okamura, H; Özel-Tashenov, B; Ponomarev, V Yu; Richter, A; Rubio, B; Sakaguchi, H; Sakemi, Y; Sasamoto, Y; Shimbara, Y; Shimizu, Y; Smit, F D; Suzuki, T; Tameshige, Y; Wambach, J; Yamada, R; Yosoi, M; Zenihiro, J
2011-01-01
A benchmark experiment on 208Pb shows that polarized proton inelastic scattering at very forward angles including 0{\\deg} is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range testing up-to-date nuclear model calculations. The E1 polarizability extracted from the data provides a constraint on the neutron skin thickness in 208Pb and the poorly known density dependence of the symmetry energy, relevant to the description of neutron stars.
A HTS dipole insert coil constructed
Ballarino, A; Rey, J M; Stenvall, A; Sorbi, M; Tixador, P
2013-01-01
This report is the deliverable report 7.4.1 “A HTS dipole insert coil constructed“. The report has three parts: “Design report for the HTS dipole insert”, “One insert pancake prototype coil constructed with the setup for a high field test”, and “All insert components ordered”. The three report parts show that, although the insert construction will be only completed by end 2013, all elements are present for a successful completion and that, given the important investments done by the participants, there is a full commitment of all of them to finish the project
Pietralla, N. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Beck, O. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Besserer, J. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Brentano, P. von [Koeln Univ. (Germany). Inst. fuer Kernphysik; Eckert, T. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Fischer, R. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Fransen, C. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Herzberg, R.-D. [Koeln Univ. (Germany). Inst. fuer Kernphysik; Jaeger, D. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Jolos, R.V. [Koeln Univ. (Germany). Inst. fuer Kernphysik]|[Bogoliubov Theoretical Laboratory, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Kneissl, U. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Krischok, B. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Margraf, J. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Maser, H. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Nord, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Pitz, H.H. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Rittner, M. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Schiller, A. [Institut fuer Strahlenphysik, Universitaet Stuttgart, 70569 Stuttgart (Germany); Zilges, A. [Koeln Univ. (Germany). Inst. fuer Kernphysik]|[WNSL, Yale University, P.O. Box 208124, New Haven, CT 06520-8124 (United States)
1997-05-26
Photon scattering experiments have been performed on the heavy deformed nuclei {sup 178,180}Hf using an E{sub {gamma}}<4 MeV bremsstrahlung beam as a continuous energy photon source. Numerous dipole excitations have been identified from the spectra of high-resolution Ge {gamma} detectors. Spins, K quantum numbers, dipole excitation strengths, and level widths, have been extracted from the scattering cross sections. From the measured level widths lifetimes of 67 levels can be deduced. The excitation strength of the scissor mode is discussed and extends the systematics from the neighboring rare earth nuclei. Besides the {Delta}K=1 excitations other dipole excitations have been observed that are distinguished from the scissor mode states by their different decay behavior. (orig.).
Asymmetry of Neoclassical Transport by Dipole Electric Field
王中天; 王龙
2004-01-01
Effects of dipole electric fields on neoclassical transport are studied. Large asymmetry in transport is created. The dipole fields, which are in a negative R-direction, reduce the ion drift, increase electron drift, and change the steps of excursion due to collisions. It is found that different levels of dipole field intensities have different types of transport. For the lowest level of the dipole field, the transport returns to the neoclassical one. For the highest level of the dipole field, the transport is turned to be the turbulence transport similar to the pseudo-classical transport. Experimental data may be corresponded to a large level of the dipole field intensity.
1999 Review of superconducting dipole and quadrupole magnets for particle accelerators
Devred, A. [CEA/Saclay, Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France); CERN, Conseil Europeen pour la recherche nucleaire, Laboratoire europeen pour la physique des particules Geneve (Switzerland)
1999-12-01
The quest for elementary particles has promoted the development of particle accelerators producing beams of increasingly higher energies. In a synchrotron-type accelerator, the particle energy is directly proportional to the product of the machine's radius times the bending magnets' field strength. Present proton experiments at the TeV scale require facilities with circumferences ranging from a few to tens of kilometers and relying on a large number (several hundreds to several thousands) of high field dipole magnets and high field gradient quadrupole magnets. These electro-magnets use high current density, low critical temperature superconducting cables and are cooled down at liquid helium temperature. They are among the most costly and the most challenging components of the machine. After explaining what are the various types of accelerator magnets and why they are needed (section 1), we present a brief history of large superconducting particle accelerators, and we detail ongoing superconducting accelerator magnet R and D programs around the world (Section 2). Then, we review the superconducting materials that are available at industrial scale (chiefly, NbTi and Nb3Sn), and we describe the manufacturing of NbTi wires and cables (section 3). We also present the difficulties of processing and insulating Nb3Sn conductors which, so far, have limited the use of this material in spite of its superior performances. We continue by presenting the complex formalism used to represent two-dimensional fields (section 4), and we discuss the two-dimensional current distributions that are the most appropriate for generating pure dipole and pure quadrupole fields (section 5). We explain how these ideal distributions can be approximated by so-called cos{theta} and cos{sup 2}{theta} coil designs and we describe the difficulties of realizing coil ends. Next, we present the mechanical design concepts that have been developed to restrain magnet coils and to ensure proper
Temperature dependence of a spreading width of giant dipole resonance in neutron-rich nuclei
Vdovin, A.I.; Storozhenko, A.N
2003-07-14
A temperature dependence of the spreading width of a giant dipole resonance is studied in the framework of the Quasiparticle-Phonon Model extended to finite temperature using a formalism of the Thermo Field Dynamics. Numerical calculations are performed for {sup 120}Sn and the neutron-rich double-magic isotope {sup 132}Sn It is found that the dispersion of the E1 strength function {sigma} increases with temperature.
Control of the collapse of a Bose Condensate by Optical Dipole Force
付海翔; 罗有华; 李明哲; 高波; 王育竹
2003-01-01
We propose an experimental scheme of using the far-off resonance optical dipole force to control tunable collapse of Bose-Einstein condensation with attractive interactions. This scheme can conveniently alter collapse phenomena while keeping interatomic processes unchanged. Effects on the critical interaction strength and time delay are studied with numerical simulation. We show that for the blue-detuning case those two quantities are increased while for the red-detuning case they are decreased.
Gorelik, ML; Urin, MH
2003-01-01
A description of basic properties (strength function, transition density, probabilities of direct nucleonic decays) of isoscalar giant monopole (including an overtone) and dipole resonances in medium-mass spherical nuclei is proposed within a semimicroscopic approach. The approach relies on employin
The low-energy dipole structure of 232Th , 236U and 238U actinide nuclei
Kuliev, A. A.; Guliyev, E.; Ertugral, F.; Özkan, S.
2010-03-01
In this study, ensuremath I^{π} = 1+ and ensuremath I^{π} = 1- dipole mode excitations are systematically investigated within the rotational and translational + Galilean invariant quasiparticle random-phase approximation for 232Th , 236U , and 238U actinide nuclei. It is shown that the investigated nuclei reach a B( M1) strength structure, which corresponds to the scissors mode. The calculated mean excitation energies as well as the summed B( M1) value of the scissors mode excitations are consistent with the available experimental data. The results of calculations indicate large differences to the rare-earth nuclei as is the case for the experiment: a doubling of the observed dipole strengths and a shift of the energy centroid to the lower energies by about 800keV. The calculations indicate the presence of a few prominent negative-parity ensuremath K^{π} = 1- states in the 2.0-4.0MeV energy interval. The occurrence of the negative-parity dipole states with the rather high B( E1) value less than 4MeV shows the necessity of explicit parity measurements for the correct determination of the scissors mode strength in 232Th , 236U , and 238U isotopes.
LHC Dipoles: The countdown has begun
2002-01-01
One of the LHC dipole magnets has just achieved a record magnetic field of 9 Tesla in one go without quenching. The challenge now is to increase the production rate to 35 magnets a month by 2004. As a new information panel in Building 30 shows, the countdown has begun.
The isotopic dipole moment of HDO
Assafrao, Denise; Mohallem, Jose R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, CP 702, 30123-970, Belo Horizonte, MG (Brazil)
2007-03-14
An adiabatic variational approximation is used to study the monodeuterated water molecule, HDO, accounting for the isotopic effect. The isotopic dipole moment, pointing from D to H, is then calculated for the first time, yielding (1.5 {+-} 0.1) x 10{sup -3} Debye, being helpful in the interpretation of experiments. (fast track communication)
Scattering properties of point dipole interactions
Zolotaryuk, Alexander; Christiansen, Peter Leth; Iermakova, S.V.
2006-01-01
dipole interactions with a renormalized coupling constant are analysed. Depending on the parameter values, all these interactions being self-adjoint extensions of the one-dimensional Schrodinger operator are shown to be divided into four types: (i) interactions will full transparency, (ii) non...
Installation of the ALICE dipole magnet
Maximilien Brice
2005-01-01
The large dipole magnet is installed on the ALICE detector at CERN. This magnet, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid (in the background). These muons are heavy electrons that interact less with matter, allowing them to traverse the main section of the detector.
A Microstrip Reflect Array Using Crossed Dipoles
Pozar, David M.; Targonski, Stephen D.
1998-01-01
Microstrip reflect arrays offer a flat profile and light weight, combined with many of the electrical characteristics of reflector antennas. Previous work [1]-[7] has demonstrated a variety of microstrip reflect arrays, using different elements at a range of frequencies. In this paper we describe the use of crossed dipoles as reflecting elements in a microstrip reflectarray. Theory of the solution will be described, with experimental results for a 6" square reflectarray operating at 28 GHz. The performance of crossed dipoles will be directly compared with microstrip patches, in terms of bandwidth and loss. We also comment on the principle of operation of reflectarray elements, including crossed dipoles, patches of variable length, and patch elements with tuning stubs. This research was prompted by the proposed concept of overlaying a flat printed reflectarray on the surface of a spacecraft solar panel. Combining solar panel and antenna apertures in this way would lead to a reduction in weight and simpler deployment, with some loss of flexibility in independently pointing the solar panel and the antenna. Using crossed dipoles as reflectarray elements will minimize the aperture blockage of the solar cells, in contrast to the use of elements such as microstrip patches.
Anharmonic effects and double giant dipole resonances
Voronov, V V
2001-01-01
A brief review of recent results of the microscopic calculations to describe characteristics of the double giant dipole resonances (DGDR) is presented. A special attention is paid to a microscopic study of the anharmonic properties of the DGDR. It is found that the deviation of the energy centroid of the DGDR from the harmonic limit follows A sup - sup 1 dependence
Conceptual design of Dipole Research Experiment (DREX)
Qingmei, XIAO; Zhibin, WANG; Xiaogang, WANG; Chijie, XIAO; Xiaoyi, YANG; Jinxing, ZHENG
2017-03-01
A new terrella-like device for laboratory simulation of inner magnetosphere plasmas, Dipole Research Experiment, is scheduled to be built at the Harbin Institute of Technology (HIT), China, as a major state scientific research facility for space physics studies. It is designed to provide a ground experimental platform to reproduce the inner magnetosphere to simulate the processes of trapping, acceleration, and transport of energetic charged particles restrained in a dipole magnetic field configuration. The scaling relation of hydromagnetism between the laboratory plasma of the device and the geomagnetosphere plasma is applied to resemble geospace processes in the Dipole Research Experiment plasma. Multiple plasma sources, different kinds of coils with specific functions, and advanced diagnostics are designed to be equipped in the facility for multi-functions. The motivation, design criteria for the Dipole Research Experiment experiments and the means applied to generate the plasma of desired parameters in the laboratory are also described. Supported by National Natural Science Foundation of China (Nos. 11505040, 11261140326 and 11405038), China Postdoctoral Science Foundation (Nos. 2016M591518, 2015M570283) and Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (No. 2017008).
Gravitational Radiation from Oscillating Gravitational Dipole
De Aquino, Fran
2002-01-01
The concept of Gravitational Dipole is introduced starting from the recent discovery of negative gravitational mass (gr-qc/0005107 and physics/0205089). A simple experiment, a gravitational wave transmitter, to test this new concept of gravitational radiation source is presented.
The SPS tunnel with a dipole magnet
1976-01-01
The SPS uses about 800 6-m long dipole magnets to bend the beam around its path. Particle beams come into the SPS from the smaller PS accelerator at 26 GeV. The SPS then accelerates the beam further up to 450 GeV when the beam is extracted and transferred to the LHC or CERN Neutrinos to Gran Sasso (CNGS).
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Nara, Takaaki [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Oohama, Junji [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hashimoto, Masaru [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan); Takeda, Tsunehiro [Graduate School of Frontier Science, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa, Chiba 277-8561 (Japan); Ando, Shigeru [Graduate School of Information Science and Technology, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656 (Japan)
2007-07-07
This paper presents a novel algorithm to reconstruct parameters of a sufficient number of current dipoles that describe data (equivalent current dipoles, ECDs, hereafter) from radial/vector magnetoencephalography (MEG) with and without electroencephalography (EEG). We assume a three-compartment head model and arbitrary surfaces on which the MEG sensors and EEG electrodes are placed. Via the multipole expansion of the magnetic field, we obtain algebraic equations relating the dipole parameters to the vector MEG/EEG data. By solving them directly, without providing initial parameter guesses and computing forward solutions iteratively, the dipole positions and moments projected onto the xy-plane (equatorial plane) are reconstructed from a single time shot of the data. In addition, when the head layers and the sensor surfaces are spherically symmetric, we show that the required data reduce to radial MEG only. This clarifies the advantage of vector MEG/EEG measurements and algorithms for a generally-shaped head and sensor surfaces. In the numerical simulations, the centroids of the patch sources are well localized using vector/radial MEG measured on the upper hemisphere. By assuming the model order to be larger than the actual dipole number, the resultant spurious dipole is shown to have a much smaller strength magnetic moment (about 0.05 times smaller when the SNR = 16 dB), so that the number of ECDs is reasonably estimated. We consider that our direct method with greatly reduced computational cost can also be used to provide a good initial guess for conventional dipolar/multipolar fitting algorithms.
Krugmann, Andreas; Martin, Dirk; Neumann-Cosel, Peter von; Pietralla, Norbert; Poltoratska, Iryna; Ponomarev, Vladimir [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik; Tamii, Atsushi [RCNP, Osaka University (Japan); Iwamoto, Chihiro [Konan University (Japan); Yoshida, Kenichi [Niigata University (Japan); Collaboration: E350-Collaboration
2013-07-01
Polarized proton scattering has been measured on the heavy deformed nucleus {sup 154}Sm at extreme forward angles with 300 MeV protons at RCNP, Osaka. The aim is to investigate the impact of ground state deformation on the properties of the pygmy dipole resonance (PDR) and the spin M1 resonance claimed to show a double-hump structure in heavy deformed nuclei. The (p,p') cross sections can be decomposed into E1 and M1 parts in two independent ways based either on a multipole decomposition of the cross sections or spin transfer observables. The analysis of polarization transfer observables shows dominant non-spinflip cross sections in the excitation energy region 5-9 MeV with a resonance structure interpreted as the PDR, while the spinflip M1 strength shows a broad distribution between 5 and 10 MeV.
Is there correlation between fine structure and dark energy cosmic dipoles?
Mariano, Antonio; Perivolaropoulos, Leandros
2012-10-01
We present a detailed analysis (including redshift tomography) of the cosmic dipoles in the Keck+VLT quasar absorber and in the Union2 SnIa samples. We show that the fine structure constant cosmic dipole obtained through the Keck+VLT quasar absorber sample at 4.1σ level is anomalously aligned with the corresponding dark energy dipole obtained through the Union2 sample at 2σ level. The angular separation between the two dipole directions is 11.3°±11.8°. We use Monte Carlo simulations to find the probability of obtaining the observed dipole magnitudes with the observed alignment, in the context of an isotropic cosmological model with no correlation between dark energy and fine structure constant α. We find that this probability is less than one part in 106. We propose a simple physical model (extended topological quintessence) which naturally predicts a spherical inhomogeneous distribution for both dark energy density and fine structure constant values. The model is based on the existence of a recently formed giant global monopole with Hubble scale core which also couples nonminimally to electromagnetism. Aligned dipole anisotropies would naturally emerge for an off-center observer for both the fine structure constant and for dark energy density. This model smoothly reduces to ΛCDM for proper limits of its parameters. Two predictions of this model are (a) a correlation between the existence of strong cosmic electromagnetic fields and the value of α and (b) the existence of a dark flow on Hubble scales due to the repulsive gravity of the global defect core (“Great Repulser”) aligned with the dark energy and α dipoles. The direction of the dark flow is predicted to be towards the spatial region of lower accelerating expansion. Existing data about the dark flow are consistent with this prediction.
A simple stochastic model for dipole moment fluctuations in numerical dynamo simulations
Meduri, Domenico G.; Wicht, Johannes
2016-04-01
Earth's axial dipole field changes in a complex fashion on many different time scales ranging from less than a year to tens of million years. Documenting, analysing, and replicating this intricate signal is a challenge for data acquisition, theoretical interpretation, and dynamo modelling alike. Here we explore whether axial dipole variations can be described by the superposition of a slow deterministic drift and fast stochastic fluctuations, i.e. by a Langevin-type system. The drift term describes the time averaged behaviour of the axial dipole variations, whereas the stochastic part mimics complex flow interactions over convective time scales. The statistical behaviour of the system is described by a Fokker-Planck equation which allows useful predictions, including the average rates of dipole reversals and excursions. We analyse several numerical dynamo simulations, most of which have been integrated particularly long in time, and also the palaeomagnetic model PADM2M which covers the past 2 Myr. The results show that the Langevin description provides a viable statistical model of the axial dipole variations on time scales longer than about 1 kyr. For example, the axial dipole probability distribution and the average reversal rate are successfully predicted. The exception is PADM2M where the stochastic model reversal rate seems too low. The dependence of the drift on the axial dipole moment reveals the nonlinear interactions that establish the dynamo balance. A separate analysis of inductive and diffusive magnetic effects in three dynamo simulations suggests that the classical quadratic quenching of induction predicted by mean-field theory seems at work.
Master equation with quantized atomic motion including dipole-dipole interactions
Damanet, François; Braun, Daniel; Martin, John
2016-05-01
We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying picture of the consequences of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and is relevant for experiments with ultracold trapped atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find analytical formulas for a number of relevant states (Gaussian states, Fock states and thermal states). In particular, we show that the dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion. The effects predicted should be experimentally observable with Rydberg atoms. FD would like to thank the F.R.S.-FNRS for financial support. FD is a FRIA Grant holder of the Fonds de la Recherche Scientifique-FNRS.
On the integrability of halo dipoles in gravity
Vieira, Werner M.; Letelier, Patricio S.
1997-01-01
We stress that halo dipole components are nontrivial in core-halo systems in both Newton's gravity and General Relativity. To this end, we extend a recent exact relativistic model to include also a halo dipole component. Next, we consider orbits evolving in the inner vacuum between a monopolar core and a pure halo dipole and find that, while the Newtonian dynamics is integrable, its relativistic counterpart is chaotic. This shows that chaoticity due only to halo dipoles is an intrinsic relati...
Color dipole chain and its hadronization in pp collision
赵晋全; 王群; 谢去病
1995-01-01
High energy pp collision is dealt with by double-string model. Each string corresponds to one initial color dipole which will radiate gluons to form color dipole chain. Such gluon radiation process is described by color dipole model. According to the quark combination rule, the total multiplicity formulae for calculating primary meson and baryon of one dipole chain are presented- The calculated yields of various final hadrons in energy range =53- 1 800GeV agree well with available data.
Absolute absorption on rubidium D1 line: including resonant dipole-dipole interactions
Weller, Lee; Siddons, Paul; Adams, Charles S; Hughes, Ifan G
2011-01-01
Here we report on measurements of the absolute absorption spectra of dense rubidium vapour on the D1 line in the weak-probe regime for temperatures up to 170 C and number densities up to 3 \\times 10^14 cm^-3. In such vapours, modifications to the homogeneous linewidth of optical transitions arise due to dipole-dipole interactions between identical atoms, in superpositions of the ground and excited states. Absolute absorption spectra were recorded with deviation of 0.1% between experiment and a theory incorporating resonant dipole-dipole interactions. The manifestation of dipole-dipole interactions is a self-broadening contribution to the homogeneous linewidth, which grows linearly with number density of atoms. Analysis of the absolute absorption spectra allow us to ascertain the value of the self-broadening coefficient for the rubidium D1 line: \\beta/2\\pi = (0.69 \\pm 0.04) \\times 10^-7 Hz cm^3, in excellent agreement with the theoretical prediction.
Mu, Yan; Gao, Yi Qin
2007-09-01
We studied the effects of hydrophobicity and dipole-dipole interactions between the nearest-neighbor amide planes on the secondary structures of a model polypeptide by calculating the free energy differences between different peptide structures. The free energy calculations were performed with low computational costs using the accelerated Monte Carlo simulation (umbrella sampling) method, with a bias-potential method used earlier in our accelerated molecular dynamics simulations. It was found that the hydrophobic interaction enhances the stability of α helices at both low and high temperatures but stabilizes β structures only at high temperatures at which α helices are not stable. The nearest-neighbor dipole-dipole interaction stabilizes β structures under all conditions, especially in the low temperature region where α helices are the stable structures. Our results indicate clearly that the dipole-dipole interaction between the nearest neighboring amide planes plays an important role in determining the peptide structures. Current research provides a more unified and quantitative picture for understanding the effects of different forms of interactions on polypeptide structures. In addition, the present model can be extended to describe DNA/RNA, polymer, copolymer, and other chain systems.
A dipole moment of the microwave background as a cosmological effect
Paczynski, Bohdan; Piran, Tsvi
1990-01-01
A spherically symmetrical Tolman-Bondi cosmological model is presented in which the curvature of space and the entropy variety with distance from the center. The dipole and quadrupole moments in the distribution of the microwave background radiation are calculated as a function of cosmic time and position of an observer, assuming that the distance to the horizon is much smaller than any characteristic scale in the model. The quadrupole moment is found to be affected mostly by the gradient in the curvature of space while the dipole moment is dominated by the gradient of entropy. The results indicate that the observed dipole in the microwave background may be cosmological in origin. Observational tests of this argument are suggested.
On the Interface Dipole at the Pentacene−Fullerene Heterojunction: A Theoretical Study
Linares, Mathieu
2010-02-25
The electronic structure at organic/organic interfaces plays a key role, among others, in defining the quantum efficiency of organics-based photovoltaic cells. Here, we perform quantum-chemical and microelectrostatic calculations on molecular aggregates of various sizes and shapes to characterize the interfacial dipole moment at pentacene/C60 heterojunctions. The results show that the interfacial dipole mostly originates in polarization effects due to the asymmetry in the multipolar expansion of the electronic density distribution between the interacting molecules, rather than in a charge transfer from donor to acceptor. The local dipole is found to fluctuate in sign and magnitude over the interface and appears as a sensitive probe of the relative arrangements of the pentacene and C60 molecules (and of the resulting local electrical fields sensed by the molecular units). © 2010 American Chemical Society.
Measurement of the Cold Dark Matter-Neutrino Dipole in the TianNu Simulation
Inman, Derek; Zhu, Hong-Ming; Emberson, J D; Pen, Ue-Li; Zhang, Tong-Jie; Yuan, Shuo; Chen, Xuelei; Xing, Zhi-Zhong
2016-01-01
Measurements of neutrino mass in cosmological observations rely on two point statistics that are hindered by significant degeneracies with the optical depth and galaxy bias. The relative velocity effect between cold dark matter and neutrinos induces a large scale dipole into the matter density field and may be able to provide orthogonal constraints to standard techniques. We numerically investigate this dipole in the TianNu Simulation, which contains cold dark matter and 50 meV neutrinos. We first compute the dipole using a new linear response technique where we treat the displacement caused by the relative velocity as a phase in Fourier space and then integrate the matter power spectrum over redshift. Then, we compute the dipole numerically in real space using the simulation density and velocity fields. We find excellent agreement between the linear response and N-body methods. Utilizing the dipole as an observational tool will require two tracers of the matter distribution that are differently biased with r...
Leung, Chui-Fan; Chow, Hak-Fun
2017-02-14
Two isomeric bottlebrush polyamides P-1 and A-1 having the same repeating monomer dipole units aligned along the polymer backbone in pseudo-parallel and pseudo-anti-parallel, respectively, were synthesized and characterized. Both polymers can form thermoreversible gels with aromatic solvents but P-1 was found to show inferior gelation strength as compared to that of A-1. Furthermore, despite their close structural resemblance, a 1:1 mixture of the P-1 and A-1 polymers was shown to exhibit self-sorting in the gel state. Gel formation was found to be a kinetically trapped process via H-bonding, π-π stacking interactions and side chain interdigitation. The differential gelation and self-sorting properties can be explained by the local dipole-dipole interactions originated from the different modes of backbone dipole alignment. In single gel systems, the antiparallel-aligned dipoles in A-1 facilitated a more compact molecular packing due to the enthalpically more favorable polymer chain association. On the other hand, the parallel-aligned dipoles in P-1 gave rise to a less stable head-to-head packing, which had difficulties to convert to the more stable head-to-tail packing in a kinetically trapped environment. In the mixed gel system, it is the unfavorable hetero-polymer mismatch dipole-dipole interaction that inhibited the mixing of the A-1 and P-1 polymers and led to self-sorting.
Formation and temporal evolution of the Lamb-dipole
Nielsen, A.H.; Juul Rasmussen, J.
1997-01-01
of the evolving dipoles depend on the initial condition. However, the gross properties of their evolution are only weakly dependent on the detailed structure and can be well-described by the so-called Lamb-dipole solution. The viscous decay of the Lamb-dipole, leading to an expansion and a decreasing velocity...
Dipole source localization of mouse electroencephalogram using the Fieldtrip toolbox.
Lee, Chungki; Oostenveld, Robert; Lee, Soo Hyun; Kim, Lae Hyun; Sung, Hokun; Choi, Jee Hyun
2013-01-01
The mouse model is an important research tool in neurosciences to examine brain function and diseases with genetic perturbation in different brain regions. However, the limited techniques to map activated brain regions under specific experimental manipulations has been a drawback of the mouse model compared to human functional brain mapping. Here, we present a functional brain mapping method for fast and robust in vivo brain mapping of the mouse brain. The method is based on the acquisition of high density electroencephalography (EEG) with a microarray and EEG source estimation to localize the electrophysiological origins. We adapted the Fieldtrip toolbox for the source estimation, taking advantage of its software openness and flexibility in modeling the EEG volume conduction. Three source estimation techniques were compared: Distribution source modeling with minimum-norm estimation (MNE), scanning with multiple signal classification (MUSIC), and single-dipole fitting. Known sources to evaluate the performance of the localization methods were provided using optogenetic tools. The accuracy was quantified based on the receiver operating characteristic (ROC) analysis. The mean detection accuracy was high, with a false positive rate less than 1.3% and 7% at the sensitivity of 90% plotted with the MNE and MUSIC algorithms, respectively. The mean center-to-center distance was less than 1.2 mm in single dipole fitting algorithm. Mouse microarray EEG source localization using microarray allows a reliable method for functional brain mapping in awake mouse opening an access to cross-species study with human brain.
Dipole source localization of mouse electroencephalogram using the Fieldtrip toolbox.
Chungki Lee
Full Text Available The mouse model is an important research tool in neurosciences to examine brain function and diseases with genetic perturbation in different brain regions. However, the limited techniques to map activated brain regions under specific experimental manipulations has been a drawback of the mouse model compared to human functional brain mapping. Here, we present a functional brain mapping method for fast and robust in vivo brain mapping of the mouse brain. The method is based on the acquisition of high density electroencephalography (EEG with a microarray and EEG source estimation to localize the electrophysiological origins. We adapted the Fieldtrip toolbox for the source estimation, taking advantage of its software openness and flexibility in modeling the EEG volume conduction. Three source estimation techniques were compared: Distribution source modeling with minimum-norm estimation (MNE, scanning with multiple signal classification (MUSIC, and single-dipole fitting. Known sources to evaluate the performance of the localization methods were provided using optogenetic tools. The accuracy was quantified based on the receiver operating characteristic (ROC analysis. The mean detection accuracy was high, with a false positive rate less than 1.3% and 7% at the sensitivity of 90% plotted with the MNE and MUSIC algorithms, respectively. The mean center-to-center distance was less than 1.2 mm in single dipole fitting algorithm. Mouse microarray EEG source localization using microarray allows a reliable method for functional brain mapping in awake mouse opening an access to cross-species study with human brain.
Laminar and transitional liquid metal duct flow near a magnetic point dipole
Tympel, Saskia; Schumacher, Jörg
2013-01-01
The flow transformation and the generation of vortex structures by a strong magnetic dipole field in a liquid metal duct flow is studied by means of three-dimensional direct numerical simulations. The dipole is considered as the paradigm for a magnetic obstacle which will deviate the streamlines due to Lorentz forces acting on the fluid elements. The duct is of square cross-section. The dipole is located above the top wall and is centered in spanwise direction. Our model uses the quasi-static approximation which is applicable in the limit of small magnetic Reynolds numbers. The analysis covers the stationary flow regime at small hydrodynamic Reynolds numbers $Re$ as well as the transitional time-dependent regime at higher values which may generate a turbulent flow in the wake of the magnetic obstacle. We present a systematic study of these two basic flow regimes and their dependence on $Re$ and on the Hartmann number $Ha$, a measure of the strength of the magnetic dipole field. Furthermore, three orientations...
Hannemann, Frank; Guyot, Arnaud; Zöllner, Andy; Müller, Jürgen J; Heinemann, Udo; Bernhardt, Rita
2009-07-01
Dipole moments of proteins arise from helical dipoles, hydrogen bond networks and charged groups at the protein surface. High protein dipole moments were suggested to contribute to the electrostatic steering between redox partners in electron transport chains of respiration, photosynthesis and steroid biosynthesis, although so far experimental evidence for this hypothesis was missing. In order to probe this assumption, we changed the dipole moment of the electron transfer protein adrenodoxin and investigated the influence of this on protein-protein interactions and electron transfer. In bovine adrenodoxin, the [2Fe-2S] ferredoxin of the adrenal glands, a dipole moment of 803 Debye was calculated for a full-length adrenodoxin model based on the Adx(4-108) and the wild type adrenodoxin crystal structures. Large distances and asymmetric distribution of the charged residues in the molecule mainly determine the observed high value. In order to analyse the influence of the resulting inhomogeneous electric field on the biological function of this electron carrier the molecular dipole moment was systematically changed. Five recombinant adrenodoxin mutants with successively reduced dipole moment (from 600 to 200 Debye) were analysed for their redox properties, their binding affinities to the redox partner proteins and for their function during electron transfer-dependent steroid hydroxylation. None of the mutants, not even the quadruple mutant K6E/K22Q/K24Q/K98E with a dipole moment reduced by about 70% showed significant changes in the protein function as compared with the unmodified adrenodoxin demonstrating that neither the formation of the transient complex nor the biological activity of the electron transfer chain of the endocrine glands was affected. This is the first experimental evidence that the high dipole moment observed in electron transfer proteins is not involved in electrostatic steering among the proteins in the redox chain.
Dipole vortices in the Great Australian Bight
Cresswell, George R.; Lund-Hansen, Lars C.; Nielsen, Morten Holtegaard
2015-01-01
Shipboard measurements from late 2006 made by the Danish Galathea 3 Expedition and satellite sea surface temperature images revealed a chain of cool and warm mushroom' dipole vortices that mixed warm, salty, oxygen-poor waters on and near the continental shelf of the Great Australian Bight (GAB......) with cooler, fresher, oxygen-rich waters offshore. The alternating jets' flowing into the mushrooms were directed mainly northwards and southwards and differed in temperature by only 1.5 degrees C; however, the salinity difference was as much as 0.5, and therefore quite large. The GAB waters were slightly...... denser than the cooler offshore waters. The field of dipoles evolved and distorted, but appeared to drift westwards at 5km day-1 over two weeks, and one new mushroom carried GAB water southwards at 7km day(-1). Other features encountered between Cape Leeuwin and Tasmania included the Leeuwin Current...
Directional Dipole Model for Subsurface Scattering
Frisvad, Jeppe Revall; Hachisuka, Toshiya; Kjeldsen, Thomas Kim
2014-01-01
Rendering translucent materials using Monte Carlo ray tracing is computationally expensive due to a large number of subsurface scattering events. Faster approaches are based on analytical models derived from diffusion theory. While such analytical models are efficient, they miss out on some...... point source diffusion. A ray source corresponds better to the light that refracts through the surface of a translucent material. Using this ray source, we are able to take the direction of the incident light ray and the direction toward the point of emergence into account. We use a dipole construction...... similar to that of the standard dipole model, but we now have positive and negative ray sources with a mirrored pair of directions. Our model is as computationally efficient as existing models while it includes single scattering without relying on a separate Monte Carlo simulation, and the rendered images...
"Good-Walker" + QCD dipoles = Hard Diffraction
Peschanski, R
1998-01-01
The Good-Walker mechanism for diffraction is shown to provide a link between total and diffractive structure functions and to be relevant for QCD calculations at small x_{Bj}. For Deep-Inelastic scattering on a small-size target (cf. an onium) the r\\^ ole of Good-Walker ``diffractive eigenstates'' is played by the QCD dipoles appearing in the $1/N_C$ limit of QCD. Hard diffraction is thus related to the QCD tripe-dipole vertex which has been recently identified (and calculated) as being a conformal invariant correlator and/or a closed-string amplitude. An extension to hard diffraction at HERA via $k_T-$factorisation of the proton vertices leads to interesting phenomenology.
Chaos in a gravitational field with dipoles
陈菊华; 王永久
2003-01-01
In this paper we investigate the dyna nics of a test particle in the gravitational field with dipoles. At first we study the gravitational potential by numerical simulations, we find that, for appropriate parameters, there are two different cases in the potential curve: one is the one-well case with a stable critical point, and the other is the three-well case with three stable critical points and two unstable critical points. By performing Poincare sections for different values of the parameters and initial conditions, we find a regular motion and a chaotic motion. From these Poincare sections,we further confirm that the chaotic motion of the test particle originates mainly from the dipoles.
RHIC AC DIPOLE DESIGN AND CONSTRUCTION.
BAI,M.; METH,M.; PAI,C.; PARKER,B.; PEGGS,S.; ROSER,T.; SANDERS,R.; TRBOJEVIC,D.; ZALTSMAN,A.
2001-06-18
Two ac dipoles with vertical and horizontal magnetic field have been proposed at RHIC for applications in linear and non-linear beam dynamics and spin manipulations. A magnetic field amplitude of 380 Gm is required to produce a coherent oscillation of 5 times the rms beam size at the top energy. We take the ac dipole frequency to be 1.0% of the revolution frequency away from the betatron frequency. To achieve the strong magnetic field with minimum power loss, an air-core magnet with two seven turn winding of low loss Litz wire resonating at 64 kHz is designed. The system is also designed to allow one to connect the two magnet winding in series to resonate at 37 kHz for the spin manipulation. Measurements of a half length prototype magnet are also presented.
Magnetic Dipole Band in 113^In
马克岩; 杨东; 陆景彬; 王烈林; 王辉东; 刘运祚; 刘弓冶; 李黎; 马英君; 杨森; 李广生; 贺创业; 李雪琴
2012-01-01
High spin states in the odd-A nucleus 113^In have been investigated using the re- action 110^Pd（7^Li, 4n） at a beam energy of 50 MeV. A new positive parity dipole band with the configuration of π（g9/2）^-lv（h11/2）^2 v （g7/2）^2 is established. The effective interaction V（θ） values of this band have been successfully described by a semiclassical geometric model based on shear mechanism, which show that the dipole band has the characteristics of magnetic rotation. In addition the collective rotational angular momentum for this band is extracted. The results show that the core contribution increases gradually with the increase of the rotation frequency.
3-wave mixing Josephson dipole element
Frattini, N. E.; Vool, U.; Shankar, S.; Narla, A.; Sliwa, K. M.; Devoret, M. H.
2017-05-01
Parametric conversion and amplification based on three-wave mixing are powerful primitives for efficient quantum operations. For superconducting qubits, such operations can be realized with a quadrupole Josephson junction element, the Josephson Ring Modulator, which behaves as a loss-less three-wave mixer. However, combining multiple quadrupole elements is a difficult task so it would be advantageous to have a three-wave dipole element that could be tessellated for increased power handling and/or information throughput. Here, we present a dipole circuit element with third-order nonlinearity, which implements three-wave mixing. Experimental results for a non-degenerate amplifier based on the proposed third-order nonlinearity are reported.
Minimum emittance in storage rings with uniform or nonuniform dipoles
Chun-xi Wang
2009-06-01
Full Text Available A simple treatment of minimum emittance theory in storage rings is presented, favoring vector and matrix forms for a more concise picture. Both conventional uniform dipoles and nonuniform dipoles with bending radius variation are treated. Simple formulas are given for computing the minimum emittance, optimal lattice parameters, as well as effects of nonoptimal parameters. For nonuniform dipoles, analytical results are obtained for a three-piece sandwich dipole model. Minimization of the effective emittance for light sources is given in detail. Usefulness of gradient and/or nonuniform dipoles for reducing the effective emittance is addressed.
Trapped field internal dipole superconducting motor generator
Hull, John R. (Downers Grove, IL)
2001-01-01
A motor generator including a high temperature superconductor rotor and an internally disposed coil assembly. The motor generator superconductor rotor is constructed of a plurality of superconductor elements magnetized to produce a dipole field. The coil assembly can be either a conventional conductor or a high temperature superconductor. The superconductor rotor elements include a magnetization direction and c-axis for the crystals of the elements and which is oriented along the magnetization direction.
Electric dipole moment of light nuclei
Afnan, Iraj R.; Gibson, Benjamin F.
2010-07-01
We examine the sensitivity of the deuteron Electric Dipole Moment (EDM) to variation in the nucleon-nucleon interaction. In particular, we write the EDM as a sum of two terms, one depends on the target wave function, the second on intermediate multiple scattering states in the 3P1 channel. This second contribution is sensitive to off-shell behavior of the 3P1 amplitude.
Electric dipole moment of light nuclei
Gibson, Benjamin [Los Alamos National Laboratory; Afnan, I R [Los Alamos National Laboratory
2010-01-01
We examine the sensitivity of the deuteron Electric Dipole Moment (EDM) to variation in the nucleon-nucleon interaction. In particular, we write the EDM as a sum of two terms, one depends on the target wave function, the second on intermediate multiple scattering states in the {sup 3}P{sub 1} channel. This second contribution is sensitive to off-shell behavior of the {sup 3}P{sub 1} amplitude.
Electric dipole moment of light nuclei
Gibson, Benjamin [Los Alamos National Laboratory; Afnan, I R [Los Alamos National Laboratory
2010-01-01
We examine the sensitivity of the deuteron Electric Dipole Moment (EDM) to variation in the nucleon-nucleon interaction. In particular, we write the EDM as a sum of two terms, one depends on the target wave function, the second on intermediate multiple scattering states in the {sup 3}P{sub 1} channel. This second contribution is sensitive to off-shell behavior of the {sup 3}P{sub 1} amplitude.
Analog of landau Levels to Electric Dipole
Ribeiro, L R; Nascimento, J R; Furtado, Claudio
2006-01-01
In this article we discuss the analogy between the dynamics of a neutral particle with an electric dipole, in the presence of configuration of magnetic field, with Landau level quantization for charged particle. We analyze this quantization based on the He-Mckelar-Wilkens interaction developed of similar way that Ericsson and Sj\\"oqvist[Phys Rev. A {\\bf 65} 013607 (2001)] was analyzed the Landau-Aharonov-Casher effect. The energy level and eingenfuctions and eigenvalues are obtained.
On the Neutron Electric Dipole Moment
Z. Bentalha; O. Lazrec
2004-01-01
@@ Within the Kobayashi-Maskawa mechanism of electroweak interaction and using the recent measured mass of the top quark, we estimate the neutron electric dipole moment (NEDM) via the diquark electroweak interaction.The resulting moment is about 10-30 e cm. The actual upper bound on the NEDM is 6.3 × 10-26 ecm and it can reach the value 5 × 10-28 ecm predicted by experiments in recent years.
CP-violation and electric dipole moments
Le Dall, Matthias; Ritz, Adam
2013-03-01
Searches for intrinsic electric dipole moments of nucleons, atoms and molecules are precision flavour-diagonal probes of new -odd physics. We review and summarise the effective field theory analysis of the observable EDMs in terms of a general set of CP-odd operators at 1 GeV, and the ensuing model-independent constraints on new physics. We also discuss the implications for supersymmetric models, in light of the mass limits emerging from the LHC.
Bent Solenoids with Superimposed Dipole Fields
Meinke, Rainer, B.; Goodzeit, Carl, L.
2000-03-21
A conceptual design and manufacturing technique were developed for a superconducting bent solenoid magnet with a superimposed dipole field that would be used as a dispersion device in the cooling channel of a future Muon Collider. The considered bent solenoid is equivalent to a 180° section of a toroid with a major radius of ~610 mm and a coil aperture of ~416 mm. The required field components of this magnet are 4 tesla for the solenoid field and 1 tesla for the superimposed dipole field. A magnet of this size and shape, operating at these field levels, has to sustain large Lorentz forces resulting in a maximum magnetic pressure of about 2,000 psi. A flexible round mini-cable with 37 strands of Cu-NbTi was selected as the superconductor. Detailed magnetic analysis showed that it is possible to obtain the required superimposed dipole field by tilting the winding planes of the solenoid by ~25°. A complete structural analysis of the coil support system and the helium containment vessel under thermal, pressure, and Lorentz force loads was carried out using 3D finite element models of the structures. The main technical issues were studied and solutions were worked out so that a highly reliable magnet of this type can be produced at an affordable cost.
SPS Dipole Multipactor Test and TEWave Diagnostics
Caspers, F; Edwards, P; Federmann, S; Holz, M; Taborelli, M
2013-01-01
Electron cloud accumulation in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY) material. The SEY of small coated samples are usually measured in the laboratory. To further test the properties of different coating materials, RF-induced multipacting in a coaxial waveguide configuration can be performed. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed through a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to electron cyclotron resonances for given magnetic fields. Preliminary results show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the case of a large scale coating production this techniqu...
ELASTIC INTERACTION BETWEEN WEDGE DISCLINATION DIPOLE AND INTERNAL CRACK
FANG Qi-hong; LIU You-wen
2006-01-01
The system of a wedge disclination dipole interacting with an internal crack was investigated. By using the complex variable method, the closed form solutions of complex potentials to this problem were presented. The analytic formulae of the physics variables, such as stress intensity factors at the tips of the crack produced by the wedge disclination dipole and the image force acting on disclination dipole center were obtained.The influence of the orientation, the dipole arm and the location of the disclination dipole on the stress intensity factors was discussed in detail. Furthermore, the equilibrium position of the wedge disclination dipole was also examined. It is shown that the shielding or antishielding effect of the wedge disclination to the stress intensity factors is significant when the disclination dipole moves to the crack tips.
Perez, I.; Sanchez-Blazquez, P.; Zurita, A.
2007-01-01
Aims. Our aim is to study the stellar content of the bar region to constrain its formation and evolution. Methods. Line-strength indices in the bar region of a sample of 6 barred galaxies were employed to derive age and metallicity gradients along the bars using stellar population models. Results. W
Dipole oscillation modes in $\\alpha$-clustering light nuclei
He, W B; Cao, X G; Cai, X Z; Zhang, G Q
2016-01-01
The alpha cluster states are discussed in an extended quantum molecular dynamics (EQMD) model frame. Different alpha cluster structures are studied in details, such as $^8$Be two-alpha cluster structure, $^{12}$C triangle structure, $^{12}$C chain structure, $^{16}$O chain structure, $^{16}$O kite structure, and $^{16}$O square structure. The properties like width of wave packets for different alpha clusters, momentum distribution, and the binding energy among alpha clusters are studied. It is also discussed how the $\\alpha$ cluster degree of freedom affects nuclear collective vibrations. The different $\\alpha$ cluster configurations in $^{12}$C and $^{16}$O have corresponding characteristic spectra of GDR and the coherence of different alpha clusters's dipole oscillation are described in details. The number and centroid energies of peaks in the GDR spectra can be reasonably explained by the geometrical and dynamical symmetries of $\\alpha$-clustering configurations. The GDR can be regarded as a very effective...
OPERATION MODES AND CHARACTERISTICS OF PLASMA DIPOLE ANTENNA
Nikolay Nikolaevich Bogachev
2014-02-01
Full Text Available Existence modes of surface electromagnetic wave on a plasma cylinder, operating modes and characteristics of the plasma antenna were studied in this paper. Solutions of the dispersion equation of surface wave were obtained for a plasma cylinder with finite radius for different plasma density values. Operation modes of the plasma asymmetric dipole antenna with finite length and radius were researched by numerical simulation. The electric field distributions of the plasma antenna in near antenna field and the radiation pattern were obtained. These characteristics were compared to characteristics of the similar metal antenna. Numerical models verification was carried out by comparing of the counted and measured metal antenna radiation patterns.
Scipioni, Roberto; Schmidt, Diedrich A; Boero, Mauro
2009-01-14
First principles molecular dynamics simulations of an aqueous solution salt system at finite concentration containing both Na(+) and Cl(-) ions show that a change in the distribution of the molecular dipole moment of H(2)O monomers appears when ions are present in solution. Simulations suggest a lowering of the dipole moments of the water molecules in the solvation shells of Na(+) and Cl(-) as compared to the pure water case, while the dipoles of the rest of the molecules are hardly affected. However, finer analysis in terms of the Wannier centers distribution suggests a change in the electronic structure of the water molecules even in the bulk. Also a change of the H-bond network arrangement was found and correlation between dipole and MOH parameter evidences such subtle effects, suggesting a lowering of tetrahedral order in salty solutions. All these changes can be related to observable quantities such as the infrared spectra thus allowing for a rationalization of the experimental outcome on neutral aqueous solutions.
A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud
Boubert, Douglas
2016-01-01
We predict the distribution of hypervelocity stars (HVSs) ejected from the Large Magellanic Cloud (LMC), under the assumption that the dwarf galaxy hosts a central massive black hole (MBH). For the majority of stars ejected from the LMC the orbital velocity of the LMC has contributed a significant fraction of their galactic rest frame velocity, leading to a dipole density distribution on the sky. We quantify the dipole using spherical harmonic analysis and contrast with the monopole expected for HVSs ejected from the Galactic Center. There is a tendril in the density distribution that leads the LMC which is coincident with the well-known and unexplained clustering of HVSs in the constellations of Leo and Sextans. Our model is falsifiable, since it predicts that Gaia will reveal a large density of HVSs in the southern hemisphere.
Many-body dipole-induced dipole model for electrorheological fluids
Huang Ji-Ping; Yu Kin-Wah
2004-01-01
Theoretical investigations on electrorheological (ER) fluids usually rely on computer simulations. An initial approach for these studies would be the point-dipole (PD) approximation, which is known to err considerably when the particles approach and finally touch each other due to many-body and multipolar interactions. Thus various works have attempted to go beyond the PD model. Being beyond the PD model, previous attempts have been restricted to either local-field effects only or multipolar effects only, but not both. For instance, we recently proposed a dipoleinduced-dipole (DID) model which is shown to be both more accurate than the PD model and easy to use. This work is necessary because the many-body (local-field) effect is included to put forth the many-body DID model. The results show that the multipolar interactions can indeed be dominant over the dipole interaction, while the local-field effect may yield a correction.
A simple stochastic model for dipole moment fluctuations in numerical dynamo simulations
Domenico G. eMeduri
2016-04-01
Full Text Available Earth's axial dipole field changes in a complex fashion on many differenttime scales ranging from less than a year to tens of million years.Documenting, analysing, and replicating this intricate signalis a challenge for data acquisition, theoretical interpretation,and dynamo modelling alike. Here we explore whether axial dipole variationscan be described by the superposition of a slow deterministic driftand fast stochastic fluctuations, i.e. by a Langevin-type system.The drift term describes the time averaged behaviour of the axial dipole variations,whereas the stochastic part mimics complex flow interactions over convective time scales.The statistical behaviour of the system is described by a Fokker-Planck equation whichallows useful predictions, including the average rates of dipole reversals and excursions.We analyse several numerical dynamo simulations, most of which havebeen integrated particularly long in time, and also the palaeomagneticmodel PADM2M which covers the past 2 Myr.The results show that the Langevin description provides a viable statistical modelof the axial dipole variations on time scales longer than about 1 kyr.For example, the axial dipole probability distribution and the average reversalrate are successfully predicted.The exception is PADM2M where the stochastic model reversal rate seems too low.The dependence of the drift on the axial dipolemoment reveals the nonlinear interactions that establish thedynamo balance. A separate analysis of inductive and diffusive magnetic effectsin three dynamo simulations suggests that the classical quadraticquenching of induction predicted by mean-field theory seems at work.
Magnetic dipole excitations of 50Cr
Pai, H.; Beck, T.; Beller, J.; Beyer, R.; Bhike, M.; Derya, V.; Gayer, U.; Isaak, J.; Krishichayan, Kvasil, J.; Löher, B.; Nesterenko, V. O.; Pietralla, N.; Martínez-Pinedo, G.; Mertes, L.; Ponomarev, V. Yu.; Reinhard, P.-G.; Repko, A.; Ries, P. C.; Romig, C.; Savran, D.; Schwengner, R.; Tornow, W.; Werner, V.; Wilhelmy, J.; Zilges, A.; Zweidinger, M.
2016-01-01
The low-lying M 1 strength of the open-shell nucleus 50Cr has been studied with the method of nuclear resonance fluorescence up to 9.7 MeV using bremsstrahlung at the superconducting Darmstadt linear electron accelerator S-DALINAC and Compton backscattered photons at the High Intensity γ -ray Source (HI γ S ) facility between 6 and 9.7 MeV of the initial photon energy. Fifteen 1+ states have been observed between 3.6 and 9.7 MeV. Following our analysis the lowest 1+ state at 3.6 MeV can be considered as an isovector orbital mode with some spin admixture. The obtained results generally match the estimations and trends typical for the scissors-like mode. Detailed calculations within the Skyrme quasiparticle random-phase-approximation method and the large-scale shell model justify our conclusions. The calculated distributions of the orbital current for the lowest 1+-state suggest the schematic view of Lipparini and Stringari (isovector rotation-like oscillations inside the rigid surface) rather than the scissors-like picture of Lo Iudice and Palumbo. The spin M 1 resonance is shown to be mainly generated by spin-flip transitions between the orbitals of the f p shell.
Magnetic dipole excitations of $^{50}$Cr
Pai, H; Beller, J; Beyer, R; Bhike, M; Derya, V; Gayer, U; Isaak, J; Kvasil, J; Loher, B; Nesterenko, V O; Pietralla, N; Martinez-Pinedo, G; Mertes, L; Ponomarev, V Yu; Reinhard, P -G; Repko, A; Ries, P C; Romig, C; Savran, D; Schwengner, R; Tornow, W; Werner, V; Wilhelmy, J; Zilges, A; Zweidinger, M
2016-01-01
The low-lying $M1$-strength of the open-shell nucleus $^{50}$Cr has been studied with the method of nuclear resonance fluorescence up to 9.7 MeV, using bremsstrahlung at the superconducting Darmstadt linear electron accelerator S-DALINAC and Compton backscattered photons at the High Intensity $\\gamma$-ray Source (HI$\\gamma$S) facility between 6 and 9.7 MeV of the initial photon energy. Fifteen $1^{+}$ states have been observed between 3.6 and 9.7 MeV. Following our analysis, the lowest $1^{+}$ state at 3.6 MeV can be considered as an isovector orbital mode with some spin admixture. The obtained results generally match the estimations and trends typical for the scissors-like mode. Detailed calculations within the Skyrme Quasiparticle Random-Phase-Approximation method and the Large-Scale Shell Model justify our conclusions. The calculated distributions of the orbital current for the lowest $1^{+}$-state suggest the schematic view of Lipparini and Stringari (isovector rotation-like oscillations inside the rigid ...
Analysis of classical phase space and energy transfer for two rotating dipoles in an electric field
González-Férez, Rosario; Salas, J Pablo; Schmelcher, Peter
2016-01-01
We explore the classical dynamics of two interacting rotating dipoles that are fixed in the space and exposed to an external homogeneous electric field. Kinetic energy transfer mechanisms between the dipoles are investigated varying both the amount of initial excess kinetic energy of one of them and the strength of the electric field. In the field-free case, and depending on the initial excess energy an abrupt transition between equipartition and non-equipartition regimes is encountered. The study of the phase space structure of the system as well as the formulation of the Hamiltonian in an appropriate coordinate frame provide a thorough understanding of this sharp transition. When the electric field is turned on, the kinetic energy transfer mechanism is significantly more complex and the system goes through different regimes of equipartition and non-equipartition of the energy including chaotic behavior.
Foreman, Matthew R; Treasurer, Eshan; Lopez, Jehovani; Arnold, Stephen
2016-01-01
Interactions between whispering gallery modes (WGMs) and small nanoparticles are commonly modelled by treating the particle as a point dipole scatterer. This approach is assumed to be accurate as long as the nanoparticle radius, $a$, is small compared to the WGM wavelength $\\lambda$. In this article, however, we show that the large field gradients associated with the evanescent decay of a WGM causes the dipole theory to significantly underestimate the interaction strength, and hence induced WGM resonance shift, even for particles as small as $a\\sim \\lambda/10$. To mitigate this issue we employ a renormalized Born approximation to more accurately determine nanoparticle induced resonance shifts and hence enable improved particle sizing. The domain of validity of this approximation is investigated and supporting experimental results are presented.
Photon strength function deduced from photon scattering and neutron capture
Matic A.
2010-10-01
Full Text Available The dipole strength function of 78Se and 196Pt are investigated by two different experimental methods, capture of cold neutrons in 77Se and 195Pt and photon scattering experiments on 78Se and 196Pt. Considering the different ways of excitation, the strength function deduced from the results are expected to agree. The report shows the status of the data analysis and presents first preliminary results.
Morzfeld, M.; Fournier, A.; Hulot, G.
2014-12-01
We investigate the geophysical relevance of low-dimensional models of the geomagnetic dipole fieldby comparing these models to the signed relative paleomagnetic intensity over the past 2 Myr.The comparison is done via Bayesian statistics, implemented numerically by Monte Carlo (MC) sampling.We consider several MC schemes, as well as two data sets to show the robustness of our approach with respect to its numerical implementation and to the details of how the data are collected.The data we consider are the Sint-2000 [1] and PADM2M [2] data sets.We consider three stochastic differential equation (SDE) models and one deterministic model. Experiments with synthetic data show that it is feasible that a low dimensional modelcan learn the geophysical state from data of only the dipole field,and reveal the limitations of the low-dimensional models.For example, the G12 model [3] (a deterministic model that generates dipole reversals by crisis induced intermittency)can only match either one of the two important time scales we find in the data. The MC sampling approach also allows usto use the models to make predictions of the dipole field.We assess how reliably dipole reversals can be predictedwith our approach by hind-casting five reversals documented over the past 2 Myr. We find that, besides its limitations, G12 can be used to predict reversals reliably,however only with short lead times and over short horizons. The scalar SDE models on the other hand are not useful for prediction of dipole reversals.References Valet, J.P., Maynadier,L and Guyodo, Y., 2005, Geomagnetic field strength and reversal rate over the past 2 Million years, Nature, 435, 802-805. Ziegler, L.B., Constable, C.G., Johnson, C.L. and Tauxe, L., 2011, PADM2M: a penalized maximum likelihood model of the 0-2 Ma paleomagnetic axial dipole moment, Geophysical Journal International, 184, 1069-1089. Gissinger, C., 2012, A new deterministic model for chaotic reversals, European Physical Journal B, 85:137.
Dipole modes with depressed amplitudes in red giants are mixed modes
Mosser, B.; Belkacem, K.; Pinçon, C.; Takata, M.; Vrard, M.; Barban, C.; Goupil, M.-J.; Kallinger, T.; Samadi, R.
2017-02-01
Context. Seismic observations with the space-borne Kepler mission have shown that a number of evolved stars exhibit low-amplitude dipole modes, which is referred to as depressed modes. Recently, these low amplitudes have been attributed to the presence of a strong magnetic field in the stellar core of those stars. Subsequently, and based on this scenario, the prevalence of high magnetic fields in evolved stars has been inferred. It should be noted, however, that this conclusion remains indirect. Aims: We intend to study the properties of mode depression in evolved stars, which is a necessary condition before reaching conclusions about the physical nature of the mechanism responsible for the reduction of the dipole mode amplitudes. Methods: We perform a thorough characterization of the global seismic parameters of depressed dipole modes and show that these modes have a mixed character. The observation of stars showing dipole mixed modes that are depressed is especially useful for deriving model-independent conclusions on the dipole mode damping. We use a simple model to explain how mode visibilities are connected to the extra damping seen in depressed modes. Results: Observations prove that depressed dipole modes in red giants are not pure pressure modes but mixed modes. This result, observed in more than 90% of the bright stars (mV ≤ 11), invalidates the hypothesis that depressed dipole modes result from the suppression of the oscillation in the radiative core of the stars. Observations also show that, except for visibility, seismic properties of the stars with depressed modes are equivalent to those of normal stars. The measurement of the extra damping that is responsible for the reduction of mode amplitudes, without any prior on its physical nature, potentially provides an efficient tool for elucidating the mechanism responsible for the mode depression. Conclusions: The mixed nature of the depressed modes in red giants and their unperturbed global seismic
Prototype steel-concrete LEP dipole magnet
1981-01-01
The magnetic field needed in the LEP dipole magnets was rather low, of a fraction of tesla. This lead to the conception of a novel yoke structure consisting of stacks of 1.5 mm thick low-carbon steel laminations spaced by 4.1 mm with the spaces filled with concrete. The excitation coils were also very simple: aluminium bars insulated by polyester boxes in this prototype, by glass-epoxy in the final magnets. For details see LEP-Note 118,1978 and LEP-Note 233 1980. See also 8111529,7908528X.
Double giant dipole resonance in hot nuclei
Cinausero, M.; Rizzi, V.; Viesti, G.; Fabris, D.; Lunardon, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Barbui, M.; Fioretto, E.; Prete, G.; Bracco, A.; Camera, F.; Million, B.; Leoni, S.; Wieland, O.; Benzoni, G.; Brambilla, S.; Airoldi, A.; Maj, A.; Kmiecik, M
2004-02-09
Signals from Double Dipole Giant Resonances (DGDR) in hot nuclei have been searched in a {gamma}-{gamma} coincidence experiment using the HECTOR array at the Laboratori Nazionali di Legnaro. The experimental single {gamma}-ray spectrum and the projection of the {gamma}-{gamma} matrix have been compared with a standard Monte Carlo Statistical Model code including only the single GDR excitation. These calculations have been used as background to determine the extra-yield associated with the DGDR de-excitation. Results have been compared with a previous experiment confirming the presence of the DGDR excitation in fusion-evaporation reactions.
Electric-dipole transitions in 165Er
WANG Shi-Tao; ZHOU Xiao-Hong; ZHANG Yu-Hu; ZHENG Yong; LIU Min-Liang; MA Fei; HU Jun; CHEN Liang; ZHANG Xin; ZHANG Ning-Tao; ZHU Li-Hua; WU Xiao-Guang; LI Guang-Sheng
2009-01-01
High-spin states of 165Er were studied using the 160Gd(9Be, 4n)reaction at beam energies of 42 and 45 MeV. The previously known bands based on the γ5/2-[523] and γ5/2+ [642] configurations have been extended to high-spin states. Electric-dipole transitions linking these two opposite parity bands were observed. Relatively large B(E1) values have been extracted experimentally and were attributed to octupole softness.
Storage ring electric dipole moment experiments
Morse, William M.; Storage Ring EDM Collaboration
2013-10-01
Dedicated electric dipole moment (edm) searches have been done only for neutral systems. We discuss in this talk dedicated storage ring proposals for measuring edms of charged particles. The statistical error dominates over the systematic error for the neutron and mercury atom edm searches. Large numbers of particles are available today from modern polarized sources at several accelerators. A proposed proton edm experiment at BNL would improve the present proton edm limit by a factor of 104. A "precursor" deuteron edm experiment has been proposed at COSY, Juelich, Germany. This would be the first measurement of the deuteron edm.
Electric Dipole Moments and New Physics
Cirigliano, Vincenzo
2014-09-01
In this talk I will focus mostly on the role of electric dipole moments (EDMs) as probes of physics beyond the Standard Model (BSM). In the first part of the talk I will present an overview of the physics reach of various searches and I will discuss the complementarity of different EDM probes. In the second part of the talk I will discuss recent work on the computation of the BSM-induced nucleon EDM and the T-odd pion-nucleon couplings using lattice Quantum ChromoDynamics.
Spin dipole nuclear matrix elements for double beta decay nuclei by charge-exchange reactions
Ejiri, H.; Frekers, D.
2016-11-01
Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (3He, t) charge-exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) {M}α ({{SD}}) for low-lying 2- states were derived from the experimental SD strengths by referring to the experimental α = GT (Gamow-Teller) and α = F (Fermi) strengths. They are consistent with the empirical NMEs M({{SD}}) based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.
The Mean Remaining Strength Of Systems In A Stress-Strength Model
Gürler, Selma
2014-01-01
In this paper, we study the mean remaining strength of a component inthe stress-strength setup. We present the models for the mean remaining strength for systems consisting of n independent components underthe k-out-of-n:F , parallel and series configurations. We assume thatthe strengths of the components are nonidentically distributed randomvariables and components are designed under the common stress.
Banani Basu
2010-06-01
Full Text Available A method based on constricted Particle Swarm Optimization (CPSO algorithm to design a non-uniformly spaced collinear array of thin dipole antennas of unequal height is proposed. This paper presents a method for computing the appropriate excitation and geometry of individual array elements to generate a pencil beam in the vertical plane with minimum Standing Wave Ratio (SWR and fixed Side Lobe Level (SLL. Coupling effect between any two collinear center-fed thin dipole antennas having sinusoidal current distributions is analyzed using induced EMF method and minimized in terms of SWR. DRR of excitation distribution is fixed at a lower value for further mitigation of the coupling effect. Phase distribution for all the elements is kept at zero degree for broadside array. Optimization results show the effectiveness of the algorithm for the design of the array. Moreover method seems very conducive for estimating the mutual impedance between any two collinear center-fed thin dipole antennas having sinusoidal current distributions.
The optimal window for the 2MASS dipole
Chodorowski, Michal; Ciecielag, Pawel; Colombi, Stephane
2007-01-01
A comparison of the 2MASS flux dipole to the CMB dipole can serve as a method to constrain a combination of the cosmological parameter Omega_m and the luminosity bias of the 2MASS survey. For this constraint to be as tight as possible, it is necessary to maximize the correlation between the two dipoles. This can be achieved by optimizing the survey window through which the flux dipole is measured. Here we explicitly construct such a window for the 2MASS survey. The optimization essentially reduces to excluding from the calculation of the flux dipole galaxies brighter than the limiting magnitude K_min = 5 of the near-infrared K_s band. The misalignment angle between the two dipoles is a sensitive measure of their correlation: the higher the correlation, the smaller the expectation value of the angle. When our window is employed, the observed misalignment angle is expected to decrease with almost 90% confidence.
Toroidal dipole excitations in metamolecules formed by interacting plasmonic nanorods
Watson, Derek W; Ruostekoski, Janne; Fedotov, Vassili A; Zheludev, Nikolay I
2015-01-01
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 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.
Transfer matrices of dipoles with bending radius variation
无
2011-01-01
With the increasing demand of high brightness in light source, the uniform dipole can not meet the needs of low emittance, and thus the dipole with bending radius variation is introduced in this paper. The transfer matrix of a non-uniform dipole whose bending radius is linearly changed is chosen as an example and a very simple calculation formula of non-uniform dipole transfer matrices is given. The transfer matrices of some common profile non-uniform dipoles are also listed. The comparison of these transfer matrices and the matrices calculated with slices method verifies the numerical accuracy of this formula. This method can make the non-uniform beam dynamic problem simpler, very helpful for emittance research and lattice design with non-uniform dipoles.
Tsoneva, N
2007-01-01
Low-energy dipole excitations have been investigated theoretically in N=50, several N=82 isotones and the Z=50 Sn isotopes. For this purpose a method incorporating both HFB and multi-phonon QPM theory is applied. A concentration of one-phonon dipole strength located below the neutron emission threshold has been calculated in these nuclei. The analysis of the corresponding neutron and proton dipole transition densities allows to assign a genuine pattern to the low-energy excitations and making them distinct from the conventional GDR modes. Analyzing also the QRPA wave functions of the states we can identify these excitations as Pygmy Dipole Resonance (PDR) modes, recently studied also in Sn and N=82 nuclei. The results for N=50 are exploratory for an experimental project designed for the bremsstrahlung facility at the ELBE accelerator.
Angle-dependent quantum Otto heat engine based on coherent dipole-dipole coupling
Su, Shan-He; Luo, Xiao-Qing; Chen, Jin-Can; Sun, Chang-Pu
2016-08-01
Electromagnetic interactions between molecules or within a molecule have been widely observed in biological systems and exhibit broad application for molecular structural studies. Quantum delocalization of molecular dipole moments has inspired researchers to explore new avenues to utilize this physical effect for energy harvesting devices. Herein, we propose a simple model of the angle-dependent quantum Otto heat engine which seeks to facilitate the conversion of heat to work. Unlike previous studies, the adiabatic processes are accomplished by varying only the directions of the magnetic field. We show that the heat engine continues to generate power when the angle relative to the vector r joining the centres of coupled dipoles departs from the magic angle θm where the static coupling vanishes. A significant improvement in the device performance has to be attributed to the presence of the quantum delocalized levels associated with the coherent dipole-dipole coupling. These results obtained may provide a promising model for the biomimetic design and fabrication of quantum energy generators.
Howe, Lauren C; Krosnick, Jon A
2017-01-03
Attitude strength has been the focus of a huge volume of research in psychology and related sciences for decades. The insights offered by this literature have tremendous value for understanding attitude functioning and structure and for the effective application of the attitude concept in applied settings. This is the first Annual Review of Psychology article on the topic, and it offers a review of theory and evidence regarding one of the most researched strength-related attitude features: attitude importance. Personal importance is attached to an attitude when the attitude is perceived to be relevant to self-interest, social identification with reference groups or reference individuals, and values. Attaching personal importance to an attitude causes crystallizing of attitudes (via enhanced resistance to change), effortful gathering and processing of relevant information, accumulation of a large store of well-organized relevant information in long-term memory, enhanced attitude extremity and accessibility, enhanced attitude impact on the regulation of interpersonal attraction, energizing of emotional reactions, and enhanced impact of attitudes on behavioral intentions and action. Thus, important attitudes are real and consequential psychological forces, and their study offers opportunities for addressing behavioral change.
Gontijo, R. G.; Cunha, F. R.
2017-06-01
This work describes a numerical model to compute the translational and rotational motion of N spherical magnetic particles settling in a quiescent viscous fluid under creeping flow condition. The motion of the particles may be produced by the action of gravitational forces, Brownian thermal fluctuations, magnetic dipole-dipole interactions, external magnetic field, and hydrodynamic interactions. In order to avoid particle overlap, we consider a repulsive force based on a variation of a screened-Coulomb potential mixed with Hertz contact forces. The inertia of the particles is neglected so that a mobility approach to describe the hydrodynamic interactions is used. The magnetic dipoles are fixed with respect to the particles themselves. Thus they can only interact magnetically between them and with an external applied magnetic field. Therefore the effect of magnetic field moment rotation relative to the particle as a consequence of a finite amount of particle anisotropy is neglected in this work. On the other hand, the inclusion of particle viscous hydrodynamic interactions and dipolar interactions is considered in our model. Both long-range hydrodynamic and magnetic interactions are accounted by a sophisticated technique of lattice sums. This work considers several possibilities of periodic and non-periodic particle interaction schemes. This paper intends to show the benefits and disadvantages of the different approaches, including a hybrid possibility of computing periodic and non-periodic particle interactions. The well-known mean sedimentation velocity and the equilibrium magnetization of the suspension are computed to validate the numerical scheme. The comparison is performed with the existent theoretical models valid for dilute suspensions and several empirical correlations available in the current literature. In the presence of dipole-dipole particle interactions, the simulations show a non-monotonic behavior of the mean sedimentation velocity as the particle
Vanishing of dipole matrix elements at level crossings.
Kocher, C. A.
1972-01-01
Demonstration that the vanishing of certain coupling matrix elements at level crossings follow from angular momentum commutation relations. A magnetic dipole transition having delta M = plus or minus 1, induced near a crossing of the levels in a nonzero magnetic field, is found to have a dipole matrix element comparable to or smaller than the quotient of the level separation and the field. This result also applies in the analogous electric field electric dipole case.
Electric Dipole Antenna: A Source of Gravitational Radiation
Chifu E. N.
2013-07-01
Full Text Available In this article, the gravitational scalar potential due to an oscillating electric dipole antenna placed in empty space is derived. The gravitational potential obtained propagates as a wave. The gravitational waves have phase velocity equal to the speed of light in vacuum (c at the equatorial plane of the electric dipole antenna, unlike electromagnetic waves from the dipole antenna that cancel out at the equatorial plane due to charge symmetry.
Hybird of Quantum Phases for Induced Dipole Moments
Ma, Kai
2016-01-01
The quantum phase effects for induced electric and magnetic dipole moments are investigated. It is shown that the phase shift received by induced electric dipole has the same form with the one induced by magnetic dipole moment, therefore the total phase is a hybrid of these two types of phase. This feature indicates that in order to have a decisive measurement on either one of these two phases, it is necessary to measure the velocity dependence of the observed phase.
Lunar magnetic field - Permanent and induced dipole moments
Russell, C. T.; Coleman, P. J., Jr.; Schubert, G.
1974-01-01
Apollo 15 subsatellite magnetic field observations have been used to measure both the permanent and the induced lunar dipole moments. Although only an upper limit of 1.3 x 10 to the 18th gauss-cubic centimeters has been determined for the permanent dipole moment in the orbital plane, there is a significant induced dipole moment which opposes the applied field, indicating the existence of a weak lunar ionosphere.
Dual Shapiro-Virasoro amplitudes in the QCD dipole picture
Peschanski, R
1997-01-01
Using the QCD dipole picture of BFKL dynamics and the conformal invariance properties of the BFKL kernel in transverse coordinate space, we show that the 1--to--p dipole densities can be expressed in terms of dual Shapiro- Virasoro amplitudes B{2p+2} and their generalization including non-zero conformal spins. We discuss the possibility of an effective closed string theory of interacting QCD dipoles.
Strong CP violation and the neutron electric dipole form factor
Kuckei, J; Faessler, A; Gutsche, T; Kovalenko, S; Lyubovitskij, V E; Pumsa-ard, K; Dib, Claudio; Faessler, Amand; Gutsche, Th.; Kovalenko, Sergey
2005-01-01
We calculate the neutron electric dipole form factor induced by the CP violating theta-term of QCD, within a perturbative chiral quark model which includes pion and kaon clouds. On this basis we derive the neutron electric dipole moment and the electron-neutron Schiff moment. From the existing experimental upper limits on the neutron electric dipole moment we extract constraints on the theta-parameter and compare our results with other approaches.
Dipole Alignment in Rotating MHD Turbulence
Shebalin, John V.; Fu, Terry; Morin, Lee
2012-01-01
We present numerical results from long-term CPU and GPU simulations of rotating, homogeneous, magnetohydrodynamic (MHD) turbulence, and discuss their connection to the spherically bounded case. We compare our numerical results with a statistical theory of geodynamo action that has evolved from the absolute equilibrium ensemble theory of ideal MHD turbulence, which is based on the ideal MHD invariants are energy, cross helicity and magnetic helicity. However, for rotating MHD turbulence, the cross helicity is no longer an exact invariant, although rms cross helicity becomes quasistationary during an ideal MHD simulation. This and the anisotropy imposed by rotation suggests an ansatz in which an effective, nonzero value of cross helicity is assigned to axisymmetric modes and zero cross helicity to non-axisymmetric modes. This hybrid statistics predicts a large-scale quasistationary magnetic field due to broken ergodicity , as well as dipole vector alignment with the rotation axis, both of which are observed numerically. We find that only a relatively small value of effective cross helicity leads to the prediction of a dipole moment vector that is closely aligned (less than 10 degrees) with the rotation axis. We also discuss the effect of initial conditions, dissipation and grid size on the numerical simulations and statistical theory.
Electric dipole moment of ^{129}Xe atom
Singh, Yashpal; Das, B P
2013-01-01
The parity (P) and time-reversal (T) odd coupling constant associated with the tensor-pseudotensor (T-PT) electron-nucleus interaction and the nuclear Schiff moment (NSM) have been determined by combining the result of the measurement of the electric dipole moment (EDM) of ^{129}Xe atom and calculations based on the relativistic coupled-cluster (RCC) theory. Calculations using various relativistic many-body methods have been performed at different levels of approximation. The accuracies of these calculations are estimated by comparing the results of the calculated dipole polarizability of the ground state of the above atom with the most precise available experimental data. The non-linear terms that arise in the RCC theory at the singles and doubles approximation (CCSD method) were found to be crucial for achieving high accuracy in the calculations. Our results for the ^{129}Xe EDM due to the odd T-PT interaction and the NSM are, respectively, d_A=0.501 x 10^{-20} C_T |e|cm and d_A=0.336 x 10^{-17} S/(|e| fm^...
Giant dipole resonance in hot rotating nuclei
Chakrabarty, D.R. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India); Dinh Dang, N. [RIKEN, Nishina Centre for Accelerator-based Science, Saitama (Japan); VINATOM, Institute of Nuclear Science and Technique, Hanoi (Viet Nam); Datar, V.M. [Tata Institute of Fundamental Research, INO Cell, Mumbai (India)
2016-05-15
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 is discussed along with the future outlook. The interesting phenomenon of the pre-equilibrium GDR excitation in nuclear reactions is briefly addressed. (orig.)
Instability of strong magnetic field and neutrino magnetic dipole moment
Lee, Hyun Kyu
2016-01-01
Vacuum instability of the strong electromagnetic field has been discussed since long time ago. The instability of the strong electric field due to creation of electron pairs is one of the examples, which is known as Schwinger process. What matters are the coupling of particles to the electromagnetic field and the mass of the particle to be produced. The critical electric field for electrons in the minimal coupling is ~ m^2/e . Spin 1/2 neutral particles but with magnetic dipole moments can interact with the electromagnetic field through Pauli coupling. The instability of the particular vacuum under the strong magnetic field can be formulated as the emergence of imaginary parts of the effective potential. In this talk, the development of the imaginary part in the effective potential as a function of the magnetic field strength is discussed for the configurations of the uniform magnetic field and the inhomogeneous magnetic field. Neutrinos are the lightest particle(if not photon or gluon) in the "standard model...
Moles, Laser, Mirrors and the Measurement of LHC Dipole Cold Masses
2002-01-01
Marta Bajko measuring the geometry of a dipole magnet with the 3-D laser measuring machine. Over in buildings 181 and SM 18 the LHC dipole magnets await final measurements to make sure they are of exactly the right geometry (shape). And since the dipole cold masses are not straight (they are slightly bent in the horizontal plane), getting them to meet their very tight assembly tolerances of tenth of millimetre is not an easy task. 'We are aiming for one order of magnitude better than that which we actually need for the accuracy of the measurements, and old school rulers of any sort cannot handle these requirements,' says Marta Bajko, one of the project's engineers, 'for our work we need to rely on optical measuring technology.' And rely on optical measuring is exactly what they have done. The dipole measurements are being taken with a gadget called LTD 500 (Laser Tracker and Absolute Distance-Meter), created by Leica Geosystems, a Swiss Company that designs and distributes high precision measurement technol...
Valence Topological Charge-Transfer Indices for Dipole Moments: Percutaneous Enhancers
Francisco Torrens
2004-12-01
Full Text Available Valence topological charge-transfer (CT indices are applied to the calculationof dipole moments. The algebraic and vector semisum CT indices are defined. Thecombination of CT indices allows the estimation of the dipole moments. The model isgeneralized for molecules with heteroatoms. The ability of the indices for the descriptionof the molecular charge distribution is established by comparing them with the dipolemoments of homologous series of percutaneous enhancers (phenyl alcohols and4-alkylanilines. Linear and quadratic correlation models are obtained. CT indicesimprove the multivariable quadratic regression equations for the dipole moment. Thevariance decreases 97% (4-alkylanilines. No superposition of the corresponding GkÃ¢Â€Â“Jkand GkVÃ¢Â€Â“JkV pairs is observed in the fits, which diminishes the risk of co-linearity. Theinclusion of the heteroatom in the ÃÂ€-electron system is beneficial for the description ofthe dipole moment, owing to either the role of the additional p orbitals provided by theheteroatom or the role of steric factors in the ÃÂ€-electron conjugation. Inclusion of aconjugated double bond in the alkyl chain lends to more rigid structures with dipolemoment variations lower than1%.