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Sample records for coulomb energy

  1. Coulomb Energies in ^18Ne

    NASA Astrophysics Data System (ADS)

    Sherr, R.; Fortune, H. T.

    1998-10-01

    Coulomb energies of the ^18Ne mirrors of the levels of ^18O vary considerably from state to state, an effect understood as arising from their different configurations. All the low-lying positive-parity states in these nuclei can be described in terms of two nucleons coupled to an ^16O core plus a collective component (most probably four-particle two-hole (4p-2h)). We have computed Coulomb energies using one such formulation(Lawson, Serduke and Fortune, Phys. Rev. C 14), 1245 (1976).. Two-particle energies arise from coupling a neutron to single-particle states of ^17O, and a proton to the mirror states of ^17F. For the 4p-2h component, we use the ^14O-^14C mass difference, plus a ph Coulomb term(Sherr and Bertsch, Phys. Rev. C 12), 1671 (1975).. Agreement is perhaps slightly better than another such attempt(Nero, Adelberger and Dietrich, Phys. Rev. C 24), 1864 (1981). using wave functions from Benson and Flowers.

  2. Coulomb problem for vector particles : Energy spectrum.

    SciTech Connect

    Kuchiev, M. Yu.; Flambaum, V. V.; Physics; Univ. of South Wales

    2006-05-31

    The Coulomb problem for vector bosons W{+-} incorporates a well-known difficulty; the charge of the boson localized in a close vicinity of the attractive Coulomb center proves to be infinite. The paradox is shown to be resolved by the QED vacuum polarization, which brings in a strong effective repulsion that eradicates the infinite charge of the boson on the Coulomb center. This property allows one to define the Coulomb problem for vector bosons properly.

  3. Coulomb effects in low-energy nuclear fragmentation

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  4. Coulomb repulsion and the electron beam directed energy weapon

    NASA Astrophysics Data System (ADS)

    Retsky, Michael W.

    2004-09-01

    Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into small spots at large distances from defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Based on estimates, the nonreversible terms should be small - of the order of 0.1 mm. If this is true, it is possible to design a practical electron beam directed weapon not limited by Coulomb repulsion.

  5. Deep inelastic scattering at energies near the Coulomb barrier

    SciTech Connect

    Gehring, J.; Rehm, K.E.; Schiffer, J.P.

    1993-10-01

    A large yield for a process that appears to have many of the features of deep inelastic scattering has been observed at energies, near the Coulomb barrier in the systems {sup 112,124}Sn + {sup 58}Ni by Wolfs et al. In order to better understand the mechanisms by which energy dissipation takes place close to the barrier, we have extended the measurements of Wolfs to the system {sup 136}Xe + {sup 64}Ni. The use of inverse kinematics in the present measurements resulted in better mass and energy resolution due to reduced target effects and in more complete angular coverage. We have obtained angular distributions, mass distributions, and total cross sections for deep inelastic scattering at two energies near the barrier. The results on the closed neutron shell nucleus {sup 136}Xe complement those from the closed proton shell Sn nuclei.

  6. 11Li Breakup on 208 at energies around the Coulomb barrier.

    PubMed

    Fernández-García, J P; Cubero, M; Rodríguez-Gallardo, M; Acosta, L; Alcorta, M; Alvarez, M A G; Borge, M J G; Buchmann, L; Diget, C A; Falou, H A; Fulton, B R; Fynbo, H O U; Galaviz, D; Gómez-Camacho, J; Kanungo, R; Lay, J A; Madurga, M; Martel, I; Moro, A M; Mukha, I; Nilsson, T; Sánchez-Benítez, A M; Shotter, A; Tengblad, O; Walden, P

    2013-04-01

    The inclusive breakup for the (11)Li + (208)Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of (9)Li following the (11)Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbation theory of Coulomb excitation it is shown that the breakup probability data measured at small angles can be used to extract effective breakup energy as well as the slope of B(E1) distribution close to the threshold. Four-body continuum-discretized coupled-channels calculations, including both nuclear and Coulomb couplings between the target and projectile to all orders, reproduce the measured inclusive breakup cross sections and support the presence of a dipole resonance in the (11)Li continuum at low excitation energy. PMID:25166983

  7. Scattering theory and ground-state energy of Dirac fermions in graphene with two Coulomb impurities

    NASA Astrophysics Data System (ADS)

    Klöpfer, Denis; De Martino, Alessandro; Matrasulov, Davron U.; Egger, Reinhold

    2014-08-01

    We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem.

  8. Scattering of Halo Nuclei at Energies below and around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Borge, M. J. G.; Cubero, M.; Fernández-García, J. P.; Moro, A. M.; Pesudo, V.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Bender, P.; Buchmann, L.; Diget, C. A.; Di Pietro, A.; Escrig, D.; Falou, H. A.; Figuera, P. P.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Garnsworthy, A.; Gómez-Camacho, J.; Hackman, G.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Mukha, I.; Nilsson, T.; Rodríguez-Gallardo, M.; Rusek, K.; Sánchez-Benítez, A. M.; Rajabali, M.; Sarazin, F.; Shotter, A.; Tengblad, O.; Unsworth, C.; Walden, P.

    The loosely bound structure of halo nuclei is predicted to affect the collisions with heavy targets at energies around the Coulomb barrier. We report here on the results on a series of experiments done at different facilities to study the behaviour of the scattering of the archetype of the halo nuclei: 6He, 11Li, and 11Be on heavy targets at energies below and around the Coulomb barrier. The results are interpreted in the framework of Continuum-Discretized Coupled-Channel calculations (CDCC). The departure from Rutherford scattering is larger than expected. In first approximation the effect certainly scales with the loosely bound character of the projectile.

  9. Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

    SciTech Connect

    Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.

    2011-10-28

    We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

  10. Coulomb energy averaged over the nl{sup N}-atomic states with a definite spin

    SciTech Connect

    Kibler, M.; Smirnov, Yu. F.

    1995-03-05

    A purely group-theoretical approach (for which the symmetric group plays a central role), based upon the use of properties of fractional-parentage coefficients and isoscalar factors, is developed for the derivation of the Coulomb energy averaged over the states, with a definite spin, arising from an atomic configuration nl{sup N}. 15 refs.

  11. The secondary supernova machine: Gravitational compression, stored Coulomb energy, and SNII displays

    NASA Astrophysics Data System (ADS)

    Clayton, Donald D.; Meyer, Bradley S.

    2016-04-01

    Radioactive power for several delayed optical displays of core-collapse supernovae is commonly described as having been provided by decays of 56Ni nuclei. This review analyses the provenance of that energy more deeply: the form in which that energy is stored; what mechanical work causes its storage; what conservation laws demand that it be stored; and why its release is fortuitously delayed for about 106 s into a greatly expanded supernova envelope. We call the unifying picture of those energy transfers the secondary supernova machine owing to its machine-like properties; namely, mechanical work forces storage of large increases of nuclear Coulomb energy, a positive energy component within new nuclei synthesized by the secondary machine. That positive-energy increase occurs despite the fusion decreasing negative total energy within nuclei. The excess of the Coulomb energy can later be radiated, accounting for the intense radioactivity in supernovae. Detailed familiarity with this machine is the focus of this review. The stored positive-energy component created by the machine will not be reduced until roughly 106 s later by radioactive emissions (EC and β +) owing to the slowness of weak decays. The delayed energy provided by the secondary supernova machine is a few × 1049 erg, much smaller than the one percent of the 1053 erg collapse that causes the prompt ejection of matter; however, that relatively small stored energy is vital for activation of the late displays. The conceptual basis of the secondary supernova machine provides a new framework for understanding the energy source for late SNII displays. We demonstrate the nuclear dynamics with nuclear network abundance calculations, with a model of sudden compression and reexpansion of the nuclear gas, and with nuclear energy decompositions of a nuclear-mass law. These tools identify excess Coulomb energy, a positive-energy component of the total negative nuclear energy, as the late activation energy. If the

  12. Low-energy multiple-Coulomb scattering in thick foils

    SciTech Connect

    Morrill, S.M.

    1984-01-01

    Angular and energy distributions were taken using proton and ..cap alpha..-particle beams of energies 2 to 10 MeV incident on a variety of thick foils. Foils were chosen from commonly used materials and to span the periodic table. Foil thicknesses were chosen which resulted in approximately 20-60% energy losses. The lower-energy experiments were done using the Brigham Young University 4-MeV Van de Graaff accelerator while the higher-energy experiments were performed using the Triangle Universities Nuclear Laboratory (TUNL) tandem Van de Graaff. Angular distributions are characterized by the angles at which the distribution had dropped to the 1/e, 1/10, and 1/100 points of their initial values. Energy distributions are characterized by the mean energy and the width of the energy-straggling distribution of the emerging particle. Comparisons are made to the appropriate theories including the angular distribution theory of Nigam, Sundaresan, and Wu (NSW), and the straggling theory of Bethe. Improvements to the NSW method by using an effective energy and effective nuclear charge are discussed.

  13. Low-Energy Multiple-Coulomb Scattering in Thick Foils.

    NASA Astrophysics Data System (ADS)

    Morrill, Steven M.

    Angular and energy distributions were taken using proton and alpha-particle beams of energies 2--10 MeV incident on a variety of thick foils. Foils were chosen from commonly used materials and to span the periodic table. Foil thicknesses were chosen which resulted in approximately 20--60% energy losses. The lower-energy experiments were done using the Brigham Young University 4-MeV Van de Graaff accelerator while the higher-energy experiments were performed using the Triangle Universities Nuclear Laboratory (TUNL) tandem Van de Graaff. Angular distributions were characterized by the angles at which the distribution had dropped to the 1/e, 1/10, and 1/100 points of their initial values. Energy distributions were characterized by the mean energy and the width of the energy straggling distribution of the emerging particle. Comparisons were made to the appropriate theories including the angular distribution theory of Nigam, Sundaresan, and Wu (NSW), and the straggling theory of Bethe. Improvements to the NSW method by using an effective energy and effective nuclear charge were discussed.

  14. An astrophysical engine that stores gravitational work as nuclear Coulomb energy

    NASA Astrophysics Data System (ADS)

    Clayton, Donald

    2014-03-01

    I describe supernovae gravity machines that store large internal nuclear Coulomb energy, 0.80Z2A- 1 / 3MeV per nucleus. Excess of it is returned later by electron capture and positron emission. Decay energy manifests as (1) observable gamma-ray lines (2) light curves of supernovae (3) chemical energy of free carbon dissociated from CO molecules (4) huge abundances of radiogenic daughters. I illustrate by rapid silicon burning, a natural epoch in SN II. Gravitational work produces the high temperatures that photoeject nucleons and alpha particles from heavy nuclei. These are retained by other nuclei to balance photoejection rates (quasiequilibrium). The abundance distribution adjusts slowly as remaining abundance of Z = N 28Si decomposes, so p, n, α recaptures hug the Z = N line. This occurs in milliseconds, too rapidly for weak decay to alter bulk Z/N ratio. The figure displays those quasiequilibrium abundances color-coded to their decays. Z = N = 2k nuclei having k < 11 are stable, whereas k > 10 are radioactive owing to excess Coulomb energy. Weak decays radiate that excess energy weeks later to fuel the four macroscopic energetic phenomena cited. How startling to think of the Coulomb nuclear force as storing cosmic energy and its weak decay releasing macroscopic activation to SNII.

  15. Ionic recoil energies in the Coulomb explosion of metal clusters

    NASA Astrophysics Data System (ADS)

    Teuber, S.; Döppner, T.; Fennel, T.; Tiggesbäumker, J.; Meiwes-Broer, K. H.

    The photoionization of metal clusters in intense femtosecond laser fields has been studied. In contrast to an experiment on atoms, the interaction in this case leads to a very efficient and high charging of the particle where tens of electrons per atom are ejected from the cluster. The recoil energy distribution of the atomic fragment ions was measured which in the case of lead clusters exceeds 180 keV. Enhanced charging efficiency which we observed earlier for specific pulse conditions is not reflected in the recoil energy spectra. Both the average and the maximum energies decrease with increasing laser pulse width. This is in good agreement with molecular dynamics calculations.

  16. Backward scattering of low-energy antiprotons by highly charged and neutral uranium: Coulomb glory

    SciTech Connect

    Maiorova, A. V.; Telnov, D. A.; Shabaev, V. M.; Tupitsyn, I. I.; Plunien, G.; Stoehlker, T.

    2007-09-15

    Collisions of antiprotons with He-, Ne-, Ni-like, bare, and neutral uranium are studied theoretically for scattering angles close to 180 deg. and antiproton energies in the interval from 100 eV to 10 keV. We investigate the Coulomb glory effect which is caused by a screening of the Coulomb potential of the nucleus and results in a prominent maximum of the differential cross section in the backward direction at some energies of the incident particle. We found that for larger numbers of electrons in the ion the effect becomes more pronounced and shifts to higher energies of the antiproton. On the other hand, a maximum of the differential cross section in the backward direction can also be found in the scattering of antiprotons on a bare uranium nucleus. The latter case can be regarded as a manifestation of the screening property of the vacuum-polarization potential in nonrelativistic collisions of heavy particles.

  17. Coulomb screening and exciton binding energies in conjugated polymers

    NASA Astrophysics Data System (ADS)

    Moore, Eric; Gherman, Benjamin; Yaron, David

    1997-03-01

    Hartree-Fock solutions of the Pariser-Parr-Pople and MNDO Hamiltonians are shown to give reasonable predictions for the ionization potentials and electron affinities of gas-phase polyenes. However, the energy predicted for formation of a free electron-hole pair on an isolated chain of polyacetylene is much larger than that seen in the solid state. The prediction is 6.2 eV if soliton formation is ignored and about 4.7 eV if soliton formation is included. The effects of interchain interactions on the exciton binding energy are then explored using a model system consisting of one solute and one solvent polyene, that are coplanar and separated by 4 Å. The lowering of the exciton binding energy is calculated by comparing the solvation energy of the exciton state to that of a single hole (a cationic solute polyene) and a single electron (an anionic solute polyene). It is argued that when the relative timescales of charge fluctuations on the solute and solvent chains are taken into account, it is difficult to rationalize the electron-electron screening implicit in the parametrization of a single-chain Hamiltonian to solid-state data. Instead, an electron-hole screening model is developed that includes the time scales of both the electron-hole motion and the solvent polarization. The predicted solvation energies, which are saturated with respect to solute and solvent chain length, are 0.07 eV for the exciton and 0.50 eV for a well separated electron-hole pair. Given this large, 0.43 eV reduction in the exciton binding energy due to interaction with a single chain, it seems likely that interchain interactions play a central role in establishing the solid-state exciton binding energy.

  18. The {sup 6}He Optical Potential at energies around the Coulomb barrier

    SciTech Connect

    Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-26

    We present an Optical Model (OM) study of {sup 6}He on {sup 208}Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (E{sub lab} = 14, 16, 18, 22, and 27 MeV)[1]. For the projectile-target bare interaction, we use the microscopic Sao Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the alpha channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the alpha particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

  19. The 6He Optical Potential at energies around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Fernández-García, J. P.; Rodríguez-Gallardo, M.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-01

    We present an Optical Model (OM) study of 6He on 208Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (Elab = 14, 16, 18, 22, and 27 MeV) [1]. For the projectile-target bare interaction, we use the microscopic São Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the α channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the α particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

  20. Coulomb charging energy of vacancy-induced states in graphene

    NASA Astrophysics Data System (ADS)

    Miranda, V. G.; Dias da Silva, Luis G. G. V.; Lewenkopf, C. H.

    2016-08-01

    Vacancies in graphene have been proposed to give rise to π -like magnetism in carbon materials, a conjecture which has been supported by recent experimental evidence. A key element in this "vacancy magnetism" is the formation of magnetic moments in vacancy-induced electronic states. In this work we compute the charging energy U of a single-vacancy-generated localized state for bulk graphene and graphene ribbons. We use a tight-binding model to calculate the dependency of the charging energy U on the amplitudes of the localized wave function on the graphene lattice sites. We show that for bulk graphene U scales with the system size L as (lnL) -2, confirming the predictions in the literature, based on heuristic arguments. In contrast, we find that for realistic system sizes U is of the order of eV, a value that is orders of magnitude higher than the previously reported estimates. Finally, when edges are considered, we show that U is very sensitive to the vacancy position with respect to the graphene flake boundaries. In the case of armchair nanoribbons, we find a strong enhancement of U in certain vacancy positions as compared to the value for vacancies in bulk graphene.

  1. Reaction Dynamics of Weakly-Bound Few-Body Nuclei at Energies Around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Boselli, Maddalena; Diaz-Torres, Alexis

    2016-03-01

    We present a quantum reaction approach that unambiguously quantifies the complete and incomplete fusion of weakly-bound few-body nuclei. Calculations carried out within a simple model for 6Li + 209Bi at energies near the Coulomb barrier show that converged probabilities for the total, complete and incomplete fusion as well as for the scattering process can be obtained with the time-dependent wave-packet dynamics.

  2. TOPICAL REVIEW: Shapes and collectivity of exotic nuclei via low-energy Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Görgen, Andreas

    2010-10-01

    The way in which an atomic nucleus responds to excitations, whether by promoting individual nucleons into higher shells or by collective rotation or vibration, reveals many details of the underlying nuclear structure. The response of the nucleus is closely related to its macroscopic shape. Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei, allowing the measurement of static and dynamic electromagnetic moments as a probe of the nuclear wavefunctions. Owing to the availability of radioactive heavy-ion beams with energies near the Coulomb barrier, it is now possible to study the shape and collectivity of short-lived nuclei far from β stability (the so-called exotic nuclei), providing a particularly stringent test of modern theoretical nuclear structure models. This review gives an introduction to the experimental techniques related to low-energy Coulomb excitation with radioactive ion beams and summarizes the results that were obtained over the last 10 years for a wide variety of exotic nuclei at various laboratories employing the isotope separation on-line technique.

  3. Residue Coulomb Interaction Among Isobars and Its Influence in Symmetry Energy of Neutron-Rich Fragment

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Wang, Shan-Shan; Zhang, Yan-Li; Zhao, Yi-Long; Wei, Hui-Ling

    2015-09-01

    The residue Coulomb interaction (RCI), which affects the result of symmetry-energy coefficient of neutron-rich nucleus in isobaric yield ratio (IYR) method, is difficult to be determined. Four RCI approximations are investigated: (i) The M1-RCI adopting the ac/T (the ratio of Coulomb energy coefficient to temperature) determined from the IYR of mirror-nucleus fragments; (ii) The M2-RCI by fitting the difference between IYRs; (iii) The M3-RCI adopting the standard Coulomb energy at a temperature T = 2 MeV; and (iv) Neglecting the RCI among isobars. The M1-, M2- and M3-RCI are no larger than 0.4. In particular, the M2-RCI is very close to zero. The effects of RCI in asym/T of fragment are also studied. The M1- and M4-asym/T are found to be the lower and upper limitations of asym/T, respectively. The M2-asym/T overlaps the M4-asym/T, which indicates that the M2-RCI is negligible in the IYR method, and the RCI among the three isobars can be neglected. The relative consistent low values of M3-asym/T (7.5 ± 2.5) are found in very neutron-rich isobars. Supported by the Program for Science & Technology Innovation Talents in Universities of Henan Province (13HASTIT046), and Young Teacher Project in Henan Normal University (HNU), China

  4. Peculiarities of the electron energy spectrum in the Coulomb field of a superheavy nucleus

    NASA Astrophysics Data System (ADS)

    Voronov, B. L.; Gitman, D. M.; Levin, A. D.; Ferreira, R.

    2016-05-01

    We consider the peculiarities of the electron energy spectrum in the Coulomb field of a superheavy nucleus and discuss the long history of an incorrect interpretation of this problem in the case of a pointlike nucleus and its current correct solution. We consider the spectral problem in the case of a regularized Coulomb potential. For some special regularizations, we derive an exact equation for the point spectrum in the energy interval (-m,m) and find some of its solutions numerically. We also derive an exact equation for charges yielding bound states with the energy E = -m; some call them supercritical charges. We show the existence of an infinite number of such charges. Their existence does not mean that the oneparticle relativistic quantum mechanics based on the Dirac Hamiltonian with the Coulomb field of such charges is mathematically inconsistent, although it is physically unacceptable because the spectrum of the Hamiltonian is unbounded from below. The question of constructing a consistent nonperturbative second-quantized theory remains open, and the consequences of the existence of supercritical charges from the standpoint of the possibility of constructing such a theory also remain unclear.

  5. Systematical Behavior of Breakup Effects on Complete Fusion at Energies above the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Zhao, Wei-Juan; Gomes, P. R. S.; Zhao, En-Guang; Zhou, Shan-Gui

    We investigate the systematical behavior of the breakup effects on the complete fusion (CF) cross sections at energies above the Coulomb barrier. The CF cross sections are suppressed by the prompt breakup of the projectiles. This suppression effect, expressed as the ratio of the reduced fusion function and the universal fusion function (UFF), for reactions induced by the same projectile, is independent of the target and mainly determined by the lowest energy breakup channel of the projectile. There holds a good exponential relation between the suppression factor and the energy corresponding to the lowest breakup threshold.

  6. Self-energy operator for an electron in an external Coulomb potential

    SciTech Connect

    Hostler, L.C.

    1987-03-01

    The self-energy operator for an electron in an external Coulomb potential is investigated analytically using a mass eigenfunction expansion concept reported earlier. Contour integration techniques in the complex m/sup 2/ plane are used to combine bound state and continuum contributions into a single integral. The result is a relatively simple integral representation for the mass operator. Only terms ignoring the ''shift correction'' are considered in this preliminary study. A transformation to a basis of relativistic Coulomb Sturmian functions exhibits the Z..cap alpha.. dependence of the integrand in a strikingly simple way. The entire investigation is set in the framework of the ''scalar formalism'' for quantum electrodynamics investigated earlier by a number of authors and based on the ''second-order'' Dirac equation, )Pix(1+isigma)xPi+m/sup 2/)Phi = 0, where Phi is a 2 x 1 Pauli spinor.

  7. Off-energy-shell p-p scattering at sub-Coulomb energies via the Trojan horse method

    SciTech Connect

    Tumino, A.; Spitaleri, C.; Rapisarda, G. G.; Cherubini, S.; Crucilla, V.; Gulino, M.; Cognata, M. La; Lamia, L.; Pizzone, R. G.; Romano, S.; Sergi, M. L.; Mukhamedzhanov, A.; Campajola, L.; Elekes, Z.; Fueloep, Z.; Gyuerky, G.; Kiss, G.; Somorjai, E.; Gialanella, L.; Ordine, A.

    2008-12-15

    Two-proton scattering at sub-Coulomb energies has been measured indirectly via the Trojan horse method applied to the p + d{yields}p + p + n reaction to investigate off-energy shell effects for scattering processes. The three-body experiment was performed at 5 and 4.7 MeV corresponding to a p-p relative energy ranging from 80 to 670 keV. The free p-p cross section exhibits a deep minimum right within this relative energy region due to Coulomb plus nuclear destructive interference. No minimum occurs instead in the Trojan horse p-p cross section, which was extracted by employing a simple plane-wave impulse approximation. A detailed formalism was developed to build up the expression of the theoretical half-off-shell p-p cross section. Its behavior agrees with the Trojan horse data and in turn formally fits the n-n, n-p, and nuclear p-p cross sections given the fact that in its expression the Coulomb amplitude is negligible with respect to the nuclear one. These results confirm the Trojan horse suppression of the Coulomb amplitude for scattering due to the off-shell character of the process.

  8. Coulomb-driven energy boost of heavy ions for laser-plasma acceleration.

    PubMed

    Braenzel, J; Andreev, A A; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnürer, M

    2015-03-27

    An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultrathin gold foils have been irradiated by an ultrashort laser pulse at a peak intensity of 8×10^{19}  W/  cm^{2}. Highly charged gold ions with kinetic energies up to >200  MeV and a bandwidth limited energy distribution have been reached by using 1.3 J laser energy on target. 1D and 2D particle in cell simulations show how a spatial dependence on the ion's ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target, leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser-driven heavy ion acceleration. PMID:25860747

  9. Search for Monoenergetic Positron Emission from Heavy-Ion Collisions at Coulomb-Barrier Energies

    SciTech Connect

    Ahmad, I.; Back, B.B.; Betts, R.R.; Dunford, R.W.; Freer, M.; Happ, T.; Henderson, D.; Kutschera, W.; Last, J.; Lister, C.J.; Rhein, M.D.; Schiffer, J.P.; Wilt, P.; Wuosmaa, A.H.; Austin, S.M.; Kashy, E.; Maier, M.R.; Mercer, D.J.; Mikolas, D.; Winfield, J.S.; Yurkon, J.E.; Betts, R.R.; Conner, C.; Calaprice, F.P.; Young, A.; Chan, K.C.; Chishti, A.; Kaloskamis, N.I.; Xu, G.; Fox, J.D.; Roa, D.E.; Freedman, S.J.; Freer, M.; Gazes, S.B.; Schiffer, J.P.; Wolanski, M.R.; Hallin, A.L.; Liu, M.; Happ, T.; Rhein, M.D.; Perera, P.A.; Wolfs, F.L.; Trainor, T.A.

    1997-01-01

    Positron production in {sup 238}U+{sup 232}Th and {sup 238}U+{sup 181}Ta collisions near the Coulomb barrier has been studied. Earlier experiments reported narrow lines in the spectra of positrons, accumulated without the requirement of electrons detected in coincidence. No evidence of such structure is observed in the present data. The positron energy spectra are compared with estimates from dynamic atomic processes, and from internal pair conversion of electromagnetic transitions from the excited nuclei. {copyright} {ital 1997} {ital The American Physical Society}

  10. 7Be- and 8B-reaction dynamics at Coulomb barrier energies

    NASA Astrophysics Data System (ADS)

    Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Strano, E.; Torresi, D.; Yamaguchi, H.; Kahl, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Iwasa, N.; Jeong, S. C.; Jia, H. M.; Keeley, N.; Kim, Y. H.; Kimura, S.; Kubono, S.; Lay, J. A.; Lin, C. J.; Marquinez-Duran, G.; Martel, I.; Miyatake, H.; Mukai, M.; Nakao, T.; Nicoletto, M.; Pakou, A.; Rusek, K.; Sakaguchi, Y.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Stefanini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Stroe, L.; Teranishi, T.; Toniolo, N.; Wakabayashi, Y.; Watanabe, Y. X.; Yang, L.; Yang, Y. Y.

    2016-05-01

    We investigated the reaction dynamics induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target at energies around the Coulomb barrier. The two measurements are strongly interconnected, being 7Be (Sα = 1.586 MeV) the loosely bound core of the even more exotic 8B (Sp = 0.1375 MeV) nucleus. Here we summarize the present status of the data analysis for the measurement of the elastic scattering process for both reactions and the preliminary results for the optical model analysis of the collected data.

  11. An equation of state for partially ionized plasmas: The Coulomb contribution to the free energy

    SciTech Connect

    Kilcrease, D. P.; Colgan, J.; Hakel, P.; Fontes, C. J.; Sherrill, M. E.

    2015-06-20

    We have previously developed an equation of state (EOS) model called ChemEOS (Hakel and Kilcrease, Atomic Processes in Plasmas, Eds., J. Cohen et al., AIP, 2004) for a plasma of interacting ions, atoms and electrons. It is based on a chemical picture of the plasma and is derived from an expression for the Helmholtz free energy of the interacting species. All other equilibrium thermodynamic quantities are then obtained by minimizing this free energy subject to constraints, thus leading to a thermodynamically consistent EOS. The contribution to this free energy from the Coulomb interactions among the particles is treated using the method of Chabrier and Potekhin (Phys. Rev. E 58, 4941 (1998)) which we have adapted for partially ionized plasmas. This treatment is further examined and is found to give rise to unphysical behavior for various elements at certain values of the density and temperature where the Coulomb coupling begins to become significant and the atoms are partially ionized. We examine the source of this unphysical behavior and suggest corrections that produce acceptable results. The sensitivity of the thermodynamic properties and frequency-dependent opacity of iron is examined with and without these corrections. Lastly, the corrected EOS is used to determine the fractional ion populations and level populations for a new generation of OPLIB low-Z opacity tables currently being prepared at Los Alamos National Laboratory with the ATOMIC code.

  12. An equation of state for partially ionized plasmas: The Coulomb contribution to the free energy

    DOE PAGESBeta

    Kilcrease, D. P.; Colgan, J.; Hakel, P.; Fontes, C. J.; Sherrill, M. E.

    2015-06-20

    We have previously developed an equation of state (EOS) model called ChemEOS (Hakel and Kilcrease, Atomic Processes in Plasmas, Eds., J. Cohen et al., AIP, 2004) for a plasma of interacting ions, atoms and electrons. It is based on a chemical picture of the plasma and is derived from an expression for the Helmholtz free energy of the interacting species. All other equilibrium thermodynamic quantities are then obtained by minimizing this free energy subject to constraints, thus leading to a thermodynamically consistent EOS. The contribution to this free energy from the Coulomb interactions among the particles is treated using themore » method of Chabrier and Potekhin (Phys. Rev. E 58, 4941 (1998)) which we have adapted for partially ionized plasmas. This treatment is further examined and is found to give rise to unphysical behavior for various elements at certain values of the density and temperature where the Coulomb coupling begins to become significant and the atoms are partially ionized. We examine the source of this unphysical behavior and suggest corrections that produce acceptable results. The sensitivity of the thermodynamic properties and frequency-dependent opacity of iron is examined with and without these corrections. Lastly, the corrected EOS is used to determine the fractional ion populations and level populations for a new generation of OPLIB low-Z opacity tables currently being prepared at Los Alamos National Laboratory with the ATOMIC code.« less

  13. An equation of state for partially ionized plasmas: The Coulomb contribution to the free energy

    NASA Astrophysics Data System (ADS)

    Kilcrease, D. P.; Colgan, J.; Hakel, P.; Fontes, C. J.; Sherrill, M. E.

    2015-09-01

    We have previously developed an equation of state (EOS) model called ChemEOS (Hakel and Kilcrease, Atomic Processes in Plasmas, Eds., J. Cohen et al., AIP, 2004) for a plasma of interacting ions, atoms and electrons. It is based on a chemical picture of the plasma and is derived from an expression for the Helmholtz free energy of the interacting species. All other equilibrium thermodynamic quantities are then obtained by minimizing this free energy subject to constraints, thus leading to a thermodynamically consistent EOS. The contribution to this free energy from the Coulomb interactions among the particles is treated using the method of Chabrier and Potekhin (Phys. Rev. E 58, 4941 (1998)) which we have adapted for partially ionized plasmas. This treatment is further examined and is found to give rise to unphysical behavior for various elements at certain values of the density and temperature where the Coulomb coupling begins to become significant and the atoms are partially ionized. We examine the source of this unphysical behavior and suggest corrections that produce acceptable results. The sensitivity of the thermodynamic properties and frequency-dependent opacity of iron is examined with and without these corrections. The corrected EOS is used to determine the fractional ion populations and level populations for a new generation of OPLIB low-Z opacity tables currently being prepared at Los Alamos National Laboratory with the ATOMIC code.

  14. Coulomb suppression in the low-energy p-p elastic scattering via the Trojan Horse Method

    SciTech Connect

    Tumino, A.; Spitaleri, C.; Rapisarda, G. G.; Cherubini, S.; Crucilla, V.; Gulino, M.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Romano, S.; Sergi, M. L.; Mukhamedzhanov, A.; Campajola, L.; Elekes, Z.; Fueloep, Zs.; Gyuerky, G.; Kiss, G. G.; Somorjai, E.; Gialanella, L.

    2010-11-24

    We present here an important test of the main feature of the Trojan Horse Method (THM), namely the suppression of Coulomb effects in the entrance channel due to off-energy-shell effects. This is done by measuring the THM p-p elastic scattering via the p+d{yields}p+p+n reaction at 4.7 and 5 MeV, corresponding to a p-p relative energy ranging from 80 to 670 keV. In contrast to the on-energy-shell (OES) case, the extracted p-p cross section does not exhibit the Coulomb-nuclear interference minimum due to the suppression of the Coulomb amplitude. This is confirmed by the half-off-energy shell (HOES) calculations and strengthened by the agreement with the calculated OES nuclear cross sections.

  15. Breakup threshold anomaly for the 8B + 58Ni system at near-Coulomb barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Aguilera, E. F.; Gomes, P. R. S.; Lubian, J.

    2011-09-01

    By using recent fusion cross section measurements for the system 8B + 58Ni, a simultaneous analysis of elastic scattering, fusion, and total reaction cross sections is performed for the weakly bound system 8B + 58Ni at energies close to the Coulomb barrier. The analysis is carried out with an optical potential with fusion and direct reaction parts (i.e., the nuclear polarization potential U is split into a volume part UF, which accounts for fusion reactions and a surface part UDR, responsible for direct reactions). The parameters of the Woods-Saxon potentials are determined by a χ2 analysis of the data. The presence of the threshold anomaly is investigated from the energy dependence of both the fusion and direct reaction parts of the polarization potential.

  16. Coulomb Interaction Effect in Weyl Fermions with Tilted Energy Dispersion in Two Dimensions

    NASA Astrophysics Data System (ADS)

    Isobe, Hiroki; Nagaosa, Naoto

    2016-03-01

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α -(BEDT -TTF )2I3 and three-dimensional WTe2 . The Coulomb interaction between electrons modifies the velocities in an essential way in the low-energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the speed of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  17. Coulomb Interaction Effect in Weyl Fermions with Tilted Energy Dispersion in Two Dimensions.

    PubMed

    Isobe, Hiroki; Nagaosa, Naoto

    2016-03-18

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)_{2}I_{3} and three-dimensional WTe_{2}. The Coulomb interaction between electrons modifies the velocities in an essential way in the low-energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the speed of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions. PMID:27035318

  18. Coupling of Multiple Coulomb Scattering with Energy Loss and Straggling in HZETRN

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Wilson, John W.; Walker, Steven A.; Tweed, John

    2007-01-01

    The new version of the HZETRN deterministic transport code based on Green's function methods, and the incorporation of ground-based laboratory boundary conditions, has lead to the development of analytical and numerical procedures to include off-axis dispersion of primary ion beams due to small-angle multiple Coulomb scattering. In this paper we present the theoretical formulation and computational procedures to compute ion beam broadening and a methodology towards achieving a self-consistent approach to coupling multiple scattering interactions with ionization energy loss and straggling. Our initial benchmark case is a 60 MeV proton beam on muscle tissue, for which we can compare various attributes of beam broadening with Monte Carlo simulations reported in the open literature.

  19. Equation satisfied by the energy-density functional for electron-electron mutual Coulomb repulsion

    SciTech Connect

    Joubert, Daniel P.

    2011-10-15

    It is shown that the electron-electron mutual Coulomb repulsion energy-density functional V{sub ee}{sup {gamma}}[{rho}] satisfies the equationV{sub ee}{sup {gamma}}[{rho}{sub N}{sup 1}]-V{sub ee}{sup {gamma}}[{rho}{sub N-1}{sup {gamma}}]={integral}d{sup 3}r({delta}V{sub ee}{sup {gamma}}[{rho}{sub N}{sup 1}]/{delta}{rho}{sub N}{sup 1}(r))[{rho}{sub N}{sup 1}(r)-{rho}{sub N-1}{sup {gamma}}(r)], where {rho}{sub N}{sup 1}(r) and {rho}{sub N-1}{sup {gamma}}(r) are N-electron and (N-1)-electron densities determined from the same adiabatic scaled external potential of the N-electron system at coupling strength {gamma}.

  20. Threshold anomaly for the 7Be +58Ni system at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Aguilera, E. F.

    2014-12-01

    By using recent fusion cross section measurements for the weakly bound system 7Be+58Ni around the Coulomb barrier, a simultaneous χ2 analysis of elastic scattering and fusion cross section data is performed. The analysis is carried out with optical polarization potentials for the fusion and direct reaction processes. That is, the nuclear polarization potential UN is split into a volume part UF which accounts for fusion reactions and a surface part UD R that is responsible for direct reactions. The parameters of fusion and direct reaction Woods-Saxon polarization potentials are determined by the analysis of the data. The presence of the threshold anomaly is investigated from the energy dependence of these polarization potentials. It is found that, contrary to other weakly bound systems, the 7Be+58Ni reaction presents the usual threshold anomaly.

  1. Intrinsic deep hole trap levels in Cu2O with self-consistent repulsive Coulomb energy

    NASA Astrophysics Data System (ADS)

    Huang, Bolong

    2016-03-01

    The large error of the DFT+U method on full-filled shell metal oxides is due to the residue of self-energy from the localized d orbitals of cations and p orbitals of the anions. U parameters are selfconsistently found to achieve the analytical self-energy cancellation. The improved band structures based on relaxed lattices of Cu2O are shown based on minimization of self-energy error. The experimentally reported intrinsic p-type trap levels are contributed by both Cu-vacancy and the O-interstitial defects in Cu2O. The latter defect has the lowest formation energy but contributes a deep hole trap level while the Cuvacancy has higher energy cost but acting as a shallow acceptor. Both present single-particle levels spread over nearby the valence band edge, consistent to the trend of defects transition levels. By this calculation approach, we also elucidated the entanglement of strong p-d orbital coupling to unravel the screened Coulomb potential of fully filled shells.

  2. Hartree-Fock ground-state energy of anyons with no Coulomb interaction in the zero effective field

    NASA Astrophysics Data System (ADS)

    Sitko, Piotr

    1994-05-01

    We find, in the Hartree-Fock approximation, the ground-state energy of anyons with no Coulomb interaction in the case when the external magnetic field precisely cancels the average statistical field. From the point of view of the fractional quantum Hall effect it is shown that statistics transmutations to superfermions at filling fractions v = {1}/{2 p} are not energetically favourable.

  3. Elastic scattering of 17O+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.

    2016-05-01

    Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.

  4. Lower bound on the coefficient of an exchangelike energy for a single bound electron in a screened Coulomb potential

    SciTech Connect

    Nagy, I.

    2011-04-15

    The spurious self-interaction energy, which is one-half the integrated electrostatic interaction energy of a normalized electronic charge distribution with the potential field generated by itself, is calculated analytically for a 1s-like electron charge distribution governed by an attractive screened Hulthen-type model potential. The exact result obtained is used, via an energetic cancellation constraint and a convenient Hoelder's integral inequality, to deduce an analytical lower bound for the screening-dependent positive coefficient of a negative exchange-like energy term applied routinely in the local-density approximation to density functional theory with Coulomb potentials. The bare Coulomb case is investigated by Sobolev's integral inequality as well.

  5. Experimental Studies of the Coulomb Force Effects in Deuteron-Proton Break-up Reaction at Medium Energy Regime

    NASA Astrophysics Data System (ADS)

    Ciepał, I.; Parol, W.; Kalantar-Nayestanaki, N.; Khatri, G.; Kistryn, St.; Kłos, B.; Kozela, A.; Kulessa, P.; Messchendorp, J.; Skwira-Chalot, I.; Stephan, E.; Włoch, B.

    2016-03-01

    A set of differential cross-section data of the 1H(d, pp)n breakup reaction at 130 and 160 MeV deuteron beam energies has been measured in the forward polar angles domain. The data were collected with the use of the Germanium Wall (FZ Jülich) and BINA (KVI Groningen) detectors. This part of the phase-space is special with respect to the dominant Coulomb force influence on the system dynamics. The data are compared with the theoretical calculations based on the Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest.

  6. Coulomb drag

    NASA Astrophysics Data System (ADS)

    Narozhny, B. N.; Levchenko, A.

    2016-04-01

    Coulomb drag is a transport phenomenon whereby long-range Coulomb interaction between charge carriers in two closely spaced but electrically isolated conductors induces a voltage (or, in a closed circuit, a current) in one of the conductors when an electrical current is passed through the other. The magnitude of the effect depends on the exact nature of the charge carriers and the microscopic, many-body structure of the electronic systems in the two conductors. Drag measurements have become part of the standard toolbox in condensed matter physics that can be used to study fundamental properties of diverse physical systems including semiconductor heterostructures, graphene, quantum wires, quantum dots, and optical cavities.

  7. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

  8. Fusion cross sections for the {sup 9}Be+{sup 124}Sn reaction at energies near the Coulomb barrier

    SciTech Connect

    Parkar, V. V.; Palit, R.; Sharma, Sushil K.; Naidu, B. S.; Santra, S.; Mahata, K.; Ramachandran, K.; Joshi, P. K.; Rath, P. K.; Trivedi, T.; Raghav, A.

    2010-11-15

    The complete and incomplete fusion cross sections for {sup 9}Be+{sup 124}Sn reaction have been deduced using the online {gamma}-ray measurement technique. Complete fusion at energies above the Coulomb barrier was found to be suppressed by {approx}28% compared to the coupled-channels calculations and is in agreement with the systematics of L. R. Gasques et al. [Phys. Rev. C 79, 034605 (2009)]. Study of the projectile dependence for fusion on a {sup 124}Sn target shows that, for {sup 9}Be nuclei, the enhancement at below-barrier energies is substantial compared to that of tightly bound nuclei.

  9. Determination of screened Coulomb repulsion energies in organic molecular crystals: A real space approach

    NASA Astrophysics Data System (ADS)

    Cano-Cortés, Laura; Dolfen, Andreas; Merino, Jaime; Koch, Erik

    2010-06-01

    We present a general method for determining screened Coulomb parameters in molecular assemblies, in particular organic molecular crystals. This allows us to calculate the interaction parameters used in a generalized Hubbard model description of correlated organic materials. In such a model only the electrons in levels close to the Fermi level are included explicitly, while the effect of all other electrons is included as a renormalization of the model parameters. For the Coulomb integrals this renormalization is mainly due to screening. For molecular materials we can split the screening into intra- and inter-molecular screening. Here we demonstrate how the inter-molecular screening can be calculated by modeling the molecules by distributed point-polarizabilities and solving the resulting self-consistent electrostatic screening problem in real space. For the example of the quasi one-dimensional molecular metal TTF-TCNQ we demonstrate that the method gives remarkably accurate results.

  10. High energy Coulomb-scattered electrons for relativistic particle beam diagnostics

    NASA Astrophysics Data System (ADS)

    Thieberger, P.; Altinbas, Z.; Carlson, C.; Chasman, C.; Costanzo, M.; Degen, C.; Drees, K. A.; Fischer, W.; Gassner, D.; Gu, X.; Hamdi, K.; Hock, J.; Marusic, A.; Miller, T.; Minty, M.; Montag, C.; Luo, Y.; Pikin, A. I.; White, S. M.

    2016-04-01

    A new system used for monitoring energetic Coulomb-scattered electrons as the main diagnostic for accurately aligning the electron and ion beams in the new Relativistic Heavy Ion Collider (RHIC) electron lenses is described in detail. The theory of electron scattering from relativistic ions is developed and applied to the design and implementation of the system used to achieve and maintain the alignment. Commissioning with gold and 3He beams is then described as well as the successful utilization of the new system during the 2015 RHIC polarized proton run. Systematic errors of the new method are then estimated. Finally, some possible future applications of Coulomb-scattered electrons for beam diagnostics are briefly discussed.

  11. Systematic study of suppression of complete fusion in reactions involving weakly bound nuclei at energies above the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Zhao, Wei-Juan; Diaz-Torres, Alexis; Zhao, En-Guang; Zhou, Shan-Gui

    2016-01-01

    Complete fusion excitation functions of reactions involving breakup are studied by using the empirical coupled-channel (ECC) model with breakup effects considered. An exponential function with two parameters is adopted to describe the prompt-breakup probability in the ECC model. These two parameters are fixed by fitting the measured prompt-breakup probability or the complete fusion cross sections. The suppression of complete fusion at energies above the Coulomb barrier is studied by comparing the data with the predictions from the ECC model without the breakup channel considered. The results show that the suppression of complete fusion is roughly independent of the target for the reactions involving the same projectile.

  12. Coulomb three-body effects in low-energy impact ionization of H(1{ital s})

    SciTech Connect

    Roeder, J.; Rasch, J.; Jung, K.; Whelan, C.T.; Ehrhardt, H.; Allan, R.J.; Walters, H.R. |||

    1996-01-01

    The different kinematical and geometrical arrangements that may be used in ({ital e},2{ital e}) studies are briefly reviewed. The ionization of H(1{ital s}) is considered, and within the confines of a relatively simple theoretical model, it is shown how to define experimental setups where one may extract information on the role of Coulomb three-body effects in the incident and final channels. Theoretical and experimental results are presented for coplanar constant geometry where the focus is primarily on incident channel effects. {copyright} {ital 1996 The American Physical Society.}

  13. Elastic and inelastic scattering of 16O and 18O ions from 64Zn at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Salém-Vasconcelos, S.; Takagui, E. M.; Bechara, M. J.; Koide, K.; Dietzsch, O.; Bairrio Nuevo, A., Jr.; Takai, H.

    1994-08-01

    Coulomb-nuclear interference effects were investigated in the inelastic scattering of 16O and 18O by 64Zn. Measurements of elastic and inelastic angular distributions of 18O were performed at a laboratory energy of 49 MeV, over the angular range from θlab~30° to 85°. The excitation functions of 16O and 18O ions were measured at incident energies between 29 and 46 MeV at θlab=174°. The experimental angular distributions show structures which are more pronounced for projectile excitation than for target excitation. The interference minimum for the excitation of the 18O first 2+ state was found to be shifted towards forward angles by approximately 5° (c.m.) with respect to the distorted-wave Born approximation calculations and by approximately 3.5° (c.m.) with respect to the coupled-channels calculations. A pronounced Coulomb-nuclear interference minimum was seen in the excitation of 64Zn(2+) state by inelastic scattering of 16O projectiles, whereas no pronounced minimum was observed in target excitation by 18O projectiles. The elastic scattering data were analyzed with the optical model. The inelastic differential cross sections for the excitation of the first 2+ states in the target and in the 18O projectile were analyzed using the distorted-wave Born approximation and also the coupled-channels approach with collective form factors.

  14. Strong-field dissociative ionization of a linear triatomic molecule: Relationship between Coulomb-explosion energies and bond angle

    SciTech Connect

    Zhao, K.; Zhang, G.; Hill, W.T. III

    2003-12-01

    Correlation images of the symmetric six-electron Coulomb-explosion channel of CO{sub 2} were used to isolate specific geometries (linear and bent) for angular-resolved analysis of the Coulomb-explosion energy in the framework of both the critical radius R{sub c} and dynamic screening models. We show that it is possible to connect the R{sub c} and screening pictures through a single parameter, a charge defect {sigma}, which depends on the charge state and the ratio between R{sub c} and the equilibrium bond length. Our data show that R{sub c} and hence {sigma} are slow varying functions of bond angle between 145 deg. and 180 deg. with R{sub c}{approx}4 a.u. and {sigma}{approx}0.5 for the symmetric six-electron channel of CO{sub 2}. In the R{sub c} picture, the experimental value for R{sub c} is consistent with a theoretical value associated with CO{sub 2}{sup 3+}, which is considerably smaller than that associated with CO{sub 2}{sup +}({approx}6 a.u.)

  15. Interatomic Coulombic decay as a new source of low energy electrons in slow ion-dimer collisions.

    PubMed

    Iskandar, W; Matsumoto, J; Leredde, A; Fléchard, X; Gervais, B; Guillous, S; Hennecart, D; Méry, A; Rangama, J; Zhou, C L; Shiromaru, H; Cassimi, A

    2015-01-23

    We provide the experimental evidence that the single electron capture process in slow collisions between O^{3+} ions and neon dimer targets leads to an unexpected production of low-energy electrons. This production results from the interatomic Coulombic decay process, subsequent to inner-shell single electron capture from one site of the neon dimer. Although pure one-electron capture from the inner shell is expected to be negligible in the low collision energy regime investigated here, the electron production due to this process overtakes by 1 order of magnitude the emission of Auger electrons by the scattered projectiles after double-electron capture. This feature is specific to low charge states of the projectile: similar studies with Xe^{20+} and Ar^{9+} projectiles show no evidence of inner-shell single-electron capture. The dependence of the process on the projectile charge state is interpreted using simple calculations based on the classical over the barrier model. PMID:25658997

  16. Nucleon-nucleon correlations in heavy ion transfer reactions: Recent investigations at energies far below the Coulomb barrier

    SciTech Connect

    Corradi, Lorenzo

    2015-10-15

    Excitation functions of one- and two-neutron transfer channels have been measured for the {sup 96}Zr+{sup 40}Ca and {sup 116}Sn+{sup 60}Ni systems at bombarding energies ranging from the Coulomb barrier to ∼25% below. Target-like recoils have been identified in A, Z and velocity with the large solid angle magnetic spectrometer PRISMA. The experimental transfer probabilities have been compared, in absolute values and in slope, with semiclassical microscopic calculations which incorporate nucleon-nucleon pairing correlations. For the first time in a heavy ion collision, one was able to provide a consistent description of one and two neutron transfer reactions by incorporating, in the reaction mechanism, all known structure information of entrance and exit channels nuclei. In particular, there is no need to introduce any enhancement factor for the description of two neutron transfer, of course very important are the correlations induced by the pairing interaction.

  17. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    SciTech Connect

    Kuzyakin, R. A. Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-15

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the {sup 16}O + {sup 112}Cd, {sup 152}Sm, and {sup 184}W; {sup 19}F +{sup 175}Lu; {sup 28}Si +{sup 94,100}Mo and {sup 154}Sm; {sup 40}Ca +{sup 96}Zr; {sup 48}Ca+ {sup 90}Zr; and {sup 64}Ni +{sup 58,64}Ni, {sup 92,96}Zr, and {sup 100}Mo reactions are in good agreement with available experimental data.

  18. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Kuzyakin, R. A.; Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-01

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the 16O + 112Cd, 152Sm, and 184W; 19F +175Lu; 28Si +94,100Mo and 154Sm; 40Ca +96Zr; 48Ca+ 90Zr; and 64Ni +58,64Ni, 92,96Zr, and 100Mo reactions are in good agreement with available experimental data.

  19. Energies and wave functions for a soft-core Coulomb potential

    NASA Astrophysics Data System (ADS)

    Hall, Richard L.; Saad, Nasser; Sen, K. D.; Ciftci, Hakan

    2009-09-01

    For the family of model soft-core Coulomb potentials represented by V(r)=-[Z/(rq+βq)1/q] , with the parameters Z>0,β>0,q≥1 , it is shown analytically that the potentials and eigenvalues, Eνℓ , are monotonic in each parameter. The potential envelope method is applied to obtain approximate analytic estimates in terms of the known exact spectra for pure power potentials. For the case q=1 , the asymptotic iteration method is used to find exact analytic results for the eigenvalues Eνℓ and corresponding wave functions, expressed in terms of Z and β . A proof is presented establishing the general concavity of the scaled electron density near the nucleus resulting from the truncated potentials for all q . Based on an analysis of extensive numerical calculations, it is conjectured that the crossing between the pair of states [(ν,ℓ),(ν',ℓ')] is given by the conditions ν'≥(ν+1) and ℓ'≥(ℓ+3) . The significance of these results for the interaction of intense laser field with an atom is pointed out. Differences in the observed level-crossing effects between the soft-core potentials and the hydrogen atom confined inside an impenetrable sphere are discussed.

  20. Investigation of Coulombic bremsstrahlung spectra of metallic targets for the photon energy region of 1-100keV.

    PubMed

    Singh, Amrit; Dhaliwal, A S

    2016-09-01

    In the present paper, the formation of bremsstrahlung spectra by ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB) in metallic targets by (35)S beta particles has been investigated in the photon energy region of 1-100keV. From the experimental measurements and the theoretical results obtained from Elwert corrected (non-relativistic) Bethe Heitler (EBH) theory, modified Elwert factor (relativistic) (FmodBH) theories for OB and Avdonina and Pratt (FmodBH+PB) theory for total bremsstrahlung (BS) having the contribution of PB into OB, it has been found that the contribution of PB into BS in a target is limited to a low energy region only and also varies with the atomic number of target material. The FmodBH+PB theory is in agreement with the experimental results in low energy regions of the target, whereas at high energy region FmodBH is found to give better agreement. Further, the present experimental results indicate that the screening effects in the Coulombic bremsstrahlung process cannot be neglected in the high energy region, and the multiple scattering and secondary electron emissions effects in thick target are required to be taken into account in describing the bremsstrahlung process. PMID:27400163

  1. Suppression of the Coulomb Interaction in the Off-Energy-Shell p-p Scattering from the p+d{yields}p+p+n Reaction

    SciTech Connect

    Tumino, A.; Spitaleri, C.; Rapisarda, G. G.; Cherubini, S.; Crucilla, V.; Gulino, M.; La Cognata, M.; Lamia, L.; Mudo, F.; Pizzone, R. G.; Romano, S.; Sergi, M. L.; Mukhamedzhanov, A.; Elekes, Z.; Fueloep, Z.; Gyuerky, G.; Kiss, G.; Somorjai, E.

    2007-06-22

    Off-energy-shell effects in p-p scattering have been investigated at p-p relative energies from 600 down to 80 keV applying the Trojan horse method (THM) to the p+d{yields}p+p+n reaction at 5 MeV. In contrast with the on-energy-shell case, no Coulomb-nuclear interference minimum has been found in the extracted THM p-p cross section, due to the suppression of the Coulomb amplitude as predicted by the half-off-energy shell calculations. This hypothesis is strengthened by the agreement between THM p-p data and calculated on-energy-shell n+n, n+p and nuclear p+p cross sections.

  2. Image method for Coulomb energy for many-body system of charged dielectric spheres

    NASA Astrophysics Data System (ADS)

    Qin, Jian; de Pablo, Juan; Freed, Karl

    2015-03-01

    Ion polarization is important for understanding ion solvation and the stability of ion clusters in polymeric materials which typically exhibit a low and spatially inhomogeneous dielectric permittivity. The simplest approach for modeling ion polarization involves treating the ions as charged spheres with an internal dielectric permittivity differing from that of the medium. The surface polarization contribution to the electrostatic energy for a system of such dielectric spheres can be evaluated perturbatively. We derived closed-form expressions for this energy as a function of the positions of an arbitrary number of polarized surfaces. Our approach is a generalization of the image method for conducting spheres. Using this approach, we calculated the polarization corrections to the cohesion energy for ion clusters and for densely packed ionic crystals. The method can be readily adapted for investigating ion polarization effects in both Monte Carlo and molecular dynamics simulations.

  3. Kinetic energy of ions after Coulomb explosion of clusters induced by an intense laser pulse

    SciTech Connect

    Islam, Md. Ranaul; Saalmann, Ulf; Rost, Jan M.

    2006-04-15

    It is shown that the kinetic-energy distribution of ions emerging from a cluster target irradiated by an intense laser pulse arises from three main effects: (1) the spatial profile of the laser beam (2) the cluster size distribution in the experiment, and (3) possible saturation effects in the cluster ionization. Our model reveals that each of these effects leaves a characteristic fingerprint in the ion kinetic-energy spectrum. Moreover, it provides a quantitative link between observable ion spectra under experimental conditions and the ideal single-cluster result of a typical calculation.

  4. Constraining the Symmetry Energy:. a Journey in the Isospin Physics from Coulomb Barrier to Deconfinement

    NASA Astrophysics Data System (ADS)

    di Toro, M.; Colonna, M.; Greco, V.; Ferini, G.; Rizzo, C.; Rizzo, J.; Baran, V.; Gaitanos, T.; Prassa, V.; Wolter, H. H.; Zielinska-Pfabe, M.

    Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e.to the symmetry term of the nuclear Equation of State (EoS). At low energies the behavior of the symmetry energy around saturation influences dissipation and fragment production mechanisms. We will first discuss the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation during the charge equilibration in fusion and deep-inelastic collisions. Important Iso - EOS are stressed. Reactions induced by unstable 132Sn beams appear to be very promising tools to test the sub-saturation Isovector EoS. New Isospin sensitive observables are also presented for deep-inelastic, fragmentation collisions and Isospin equilibration measurements (Imbalance Ratios). The high density symmetry term can be derived from isospin effects on heavy ion reactions at relativistic energies (few AGeV range), that can even allow a "direct" study of the covariant structure of the isovector interaction in the hadron medium. Rather sensitive observables are proposed from collective flows and from pion/kaon production. The possibility of the transition to a mixed hadron-quark phase, at high baryon and isospin density, is finally suggested. Some signatures could come from an expected "neutron trapping" effect. The importance of studying violent collisions with radioactive beams from low to relativistic energies is finally stressed.

  5. Shell effects in damped collisions of Sr88 with Yb176 at the Coulomb barrier energy

    NASA Astrophysics Data System (ADS)

    Kozulin, E. M.; Knyazheva, G. N.; Dmitriev, S. N.; Itkis, I. M.; Itkis, M. G.; Loktev, T. A.; Novikov, K. V.; Baranov, A. N.; Trzaska, W. H.; Vardaci, E.; Heinz, S.; Beliuskina, O.; Khlebnikov, S. V.

    2014-01-01

    This work is a study of the influence of shell effects on the formation of binary fragments in damped collision. We have investigated binary reaction channels of the composite system with Z =108 produced in the reaction Sr88+176Yb at an energy slightly above the Bass barrier (Ec.m./EBass=1.03). Reaction products were detected by using the two-arm time-of-flight spectrometer CORSET at the K130 cyclotron of the Department of Physics, University of Jyväskylä. The mass-energy distribution of primary binary fragments has been measured. For targetlike fragments heavier than 190 u, which correspond to a mass transfer as large as twenty nucleons or more, an enhancement of the yields is observed. This striking result can be ascribed to the proton shells at Z =28 and 82 and implies the persistence of the shell effects in the formation of reaction fragments even for large mass transfers.

  6. /sup 64/Ni +/sup 92/Zr fission yields at energies close to the Coulomb barrier

    SciTech Connect

    Wolfs, F.L.H.; Janssens, R.V.F.; Holzmann, R.; Khoo, T.L.; Ma, W.C.; Sanders, S.J.

    1989-03-01

    Fission yields for the /sup 64/Ni+/sup 92/Zr reaction at laboratory energies between 240 and 300 MeV have been measured. ''Elastic scattering'' angular distributions were also obtained and used to deduce the generalized total reaction cross sections. The competition between fission and light-particle evaporation from the compound nucleus is well reproduced by statistical-model calculations. However, the calculated neutron multiplicities for this reaction are larger than those previously measured. Possible reasons for this discrepancy are discussed.

  7. Adiabatic representation in the Coulomb three-body problem in the united-atom limit: Nuclear widths of the energy levels of the muonic molecule ttµ

    NASA Astrophysics Data System (ADS)

    Melezhik, V. S.

    2016-01-01

    We study the asymptotic behavior of the wave function of the system of three Coulomb particles in the united-atom limit in the adiabatic representation of the three-body problem. This result is used to calculate the nuclear widths of muonic-molecule energy levels. We discuss features of the approach with regard to excited states of the muonic molecule ttµ with a nonzero orbital angular momentum.

  8. Impacts of the tensor couplings of ω and ρ mesons and Coulomb-exchange terms on superheavy nuclei and their relation to the symmetry energy

    NASA Astrophysics Data System (ADS)

    Liliani, N.; Nugraha, A. M.; Diningrum, J. P.; Sulaksono, A.

    2016-05-01

    We have studied the effects of tensor coupling of ω and ρ meson terms, the Coulomb exchange term in local density approximation, and various isoscalar-isovector coupling terms of relativistic mean-field model on the properties of nuclear matter, finite nuclei, and superheavy nuclei. We found that for the same fixed value of symmetry energy J or its slope L the presence of tensor coupling of ω and ρ meson terms and the Coulomb exchange term yields thicker neutron skin thickness of 208Pb. We also found that the roles of tensor coupling of ω and ρ meson terms, the Coulomb-exchange term in local density approximation, and various isoscalar-isovector coupling terms on the bulk properties of finite nuclei vary depending on the corresponding nucleus mass. However, on average, tensor coupling terms play a significant role in predicting the bulk properties of finite nuclei in a quite wide mass range, especially in binding energies. We also observed that for some particular nuclei, the corresponding experimental data of binding energies are rather less compatible with the presence of the Coulomb-exchange term in local density approximation and they tend to disfavor the presence of isoscalar-isovector coupling term with too-high Λ value. Furthermore, we have found that these terms influence the detail properties of 292120 superheavy nucleus such as binding energies, the magnitude of two-nucleon gaps, single-particle spectra, neutron densities, neutron skin thicknesses, and mean-square charge radii. However, the shell-closure predictions of 208Pb and 292120 nuclei are not affected by the presence of these terms.

  9. Multinucleon transfer study in 206Pb(18O,x ) at energies above the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Sonika, Roy, B. J.; Parmar, A.; Pal, U. K.; Kumawat, H.; Jha, V.; Pandit, S. K.; Parkar, V. V.; Ramachandran, K.; Mahata, K.; Pal, A.; Santra, S.; Mohanty, A. K.; Sekizawa, K.

    2015-08-01

    Single- and multi-nucleon transfer reactions, namely, 206Pb(18O,20O), 206Pb(18O,19O), 206Pb(18O,17O), 206Pb(18O,16O), 206Pb(18O,18N), 206Pb(18O,17N), 206Pb(18O,16N), 206Pb(18O,15N), 206Pb(18O,14N), 206Pb(18O,16C), 206Pb(18O,15C), 206Pb(18O,14C), 206Pb(18O,13C), 206Pb(18O,12C), 206Pb(18O,12B), 206Pb(18O,11B), 206Pb(18O,10B), 206Pb(18O,10Be), and 206Pb(18O,9Be), have been studied at an incident 18O energy of 139 MeV. The total kinetic energy loss (TKEL) spectrum and angular distribution of reaction products have been measured. The Q value and angle integrated cross sections are deduced. Angular distributions for the elastically scattered 18O particles are also measured. Fully microscopic time-dependent Hartree-Fock (TDHF) calculations, based on the independent single-nucleon transfer mode, have been carried out and are compared with experimental data of multinucleon transfer reactions. The TDHF calculations provide reasonable agreement with the experimental data for cases where one- and two-nucleon transfer is involved; the discrepancy is large for multinucleon transfer reactions. The effect of particle evaporation on the production cross sections has been studied. Inclusion of particle evaporation effects, though improving the results, could not reproduce the measured cross sections. Possible origins of these discrepancies are discussed.

  10. Measurements of the Coulomb dissociation cross section of 156 MeV sup 6 Li projectiles at extremely low relative fragment energies of astrophysical interest

    SciTech Connect

    Kiener, J.; Gils, H.J.; Rebel, H.; Zagromski, S.; Gsottschneider, G.; Heide, N.; Jelitto, H.; Wentz, J. ); Baur, G. )

    1991-11-01

    Coulomb dissociation of light nuclear projectiles in the electric field of heavy target nuclei has been experimentally investigated as an alternative access to radiative capture cross sections at low relative energies of the fragments, which are of astrophysical interest. As a pilot experiment the breakup of 156 MeV {sup 6}Li projectiles at {sup 208}Pb with small emission angles of the {alpha} particle and deuteron fragments has been studied. Both fragments were coincidentally detected in the focal plane of a magnetic spectrograph at several reaction angles well below the grazing angle and with relative angles between the fragments of 0{degree}--2{degree}. The experimental cross sections have been analyzed on the basis of the Coulomb breakup theory. The results for the resonant breakup give evidence for the strong dominance of the Coulomb dissociation mechanism and the absence of nuclear distortions, while the cross section for the nonresonant breakup follows theoretical predictions of the astrophysical {ital S} factor and extrapolations of corresponding radiative capture reaction cross section to very low c.m. energies of the {alpha} particle and deuteron. Various implications of the approach are discussed.

  11. Theory of strongly correlated electron systems. I. Intersite Coulomb interaction and the approximation of renormalized fermions in total energy calculations

    NASA Astrophysics Data System (ADS)

    Sandalov, I.; Lundin, U.; Eriksson, O.

    The diagrammatic strong-coupling perturbation theory (SCPT) for correlated electron systems is developed for intersite Coulomb interaction and for a nonorthogonal basis set. The construction is based on iterations of exact closed equations for many-electron Green functions (GFs) for Hubbard operators in terms of functional derivatives with respect to external sources. The graphs, which do not contain the contributions from the fluctuations of the local population numbers of the ion states, play a special role: a one-to-one correspondence is found between the subset of such graphs for the many-electron GFs and the complete set of Feynman graphs of weak-coupling perturbation theory (WCPT) for single-electron GFs. This fact is used for formulation of the approximation of renormalized Fermions (ARF) in which the many-electron quasi-particles behave analogously to normal Fermions. Then, by analyzing: (a) Sham's equation, which connects the self-energy and the exchange-correlation potential in density functional theory (DFT); and (b) the Galitskii and Migdal expressions for the total energy, written within WCPT and within ARF SCPT, a way we suggest a method to improve the description of the systems with correlated electrons within the local density approximation (LDA) to DFT. The formulation, in terms of renormalized Fermions LDA (RF LDA), is obtained by introducing the spectral weights of the many-electron GFs into the definitions of the charge density, the overlap matrices, effective mixing and hopping matrix elements, into existing electronic structure codes, whereas the weights themselves have to be found from an additional set of equations. Compared with LDA+U and self-interaction correction (SIC) methods, RF LDA has the advantage of taking into account the transfer of spectral weights, and, when formulated in terms of GFs, also allows for consideration of excitations and nonzero temperature. Going beyond the ARF SCPT, as well as RF LDA, and taking into account the

  12. Investigating Coulomb's Law.

    ERIC Educational Resources Information Center

    Noll, Ellis; Koehlinger, Mervin; Kowalski, Ludwik; Swackhamer, Gregg

    1998-01-01

    Describes the use of a computer-linked camera to demonstrate Coulomb's law. Suggests a way of reducing the difficulties in presenting Coulomb's law by teaching the inverse square law of gravity and the inverse square law of electricity in the same unit. (AIM)

  13. Coulomb Distortion in the Inelastic Regime

    SciTech Connect

    Patricia Solvignon, Dave Gaskell, John Arrington

    2009-09-01

    The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.

  14. Investigation of Neutron-Rich Osmium Isotopes in the Reaction 136Xe+208Pb at the Energies Close to Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Novikov, K.; Kozulin, E.; Dmitriev, S.; Greenlees, P.; Hannape, F.; Itkis, I. M.; Khlebnikov, S.; Knyazheva, G.; Loktev, T.; Maurer, J.; di Nitto, A.; Pakarinen, J.; Ruotsalainen, P.; Sandzelius, M.; Sorri, J.; Trzaska, W. H.; Vardaci, E.; Zagrebaev, V.

    2013-06-01

    At the present time, a great interest is paid to the research of the properties of atomic nuclei (isotopes) located far from the beta stability line. Neutron-rich osmium isotopes of multi-nucleon transfer reactions investigated in this work. The reaction 136Xe+208Pb with energy near Coulomb barrier is used for production osmium isotopes. The CORSAR-V setup was created in framework of our investigations. Method of separation volatile reaction products from non-volatile products was realized from experimental setup. The fist experimental results were obtained at this time.

  15. Observation of interatomic Coulombic decay and electron-transfer-mediated decay in high-energy electron-impact ionization of Ar2

    NASA Astrophysics Data System (ADS)

    Yan, S.; Zhang, P.; Ma, X.; Xu, S.; Li, B.; Zhu, X. L.; Feng, W. T.; Zhang, S. F.; Zhao, D. M.; Zhang, R. T.; Guo, D. L.; Liu, H. P.

    2013-10-01

    We measured the kinetic energy distributions of the fragment ions of doubly and quadruply ionized argon dimers using 3000 eV electron impact. For the dissociation of (Ar2)2+, the peak that indicates radiative charge transfer is observed, where the outer-shell ionization (dominant in highly charged ion collision) and the inner-shell ionization (preferential in x-ray experiments) have approximately equal contributions. For the dissociation of (Ar2)4+, the interatomic Coulombic decay and electron-transfer-mediated decay are first observed in the electron-impact process.

  16. Diffusion in Coulomb crystals.

    PubMed

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous. PMID:21867316

  17. Elastic scattering measurement for the system 17O + 58Ni at Coulomb barrier energies with silicon strip detectors exploiting ASIC electronics

    NASA Astrophysics Data System (ADS)

    Signorini, C.; Mazzocco, M.; Molini, P.; Pierroutsakou, D.; Boiano, C.; Manea, C.; Strano, E.; Torresi, D.; Di Meo, P.; Nicoletto, M.; Boiano, A.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; La Commara, M.; Parascandolo, C.; Parascandolo, L.; Sandoli, M.; Soramel, F.; Stroe, L.; Toniolo, N.; Veronese, F.

    2013-03-01

    The quasi elastic scattering of a 17O projectile from a 58Ni target has been studied at beam energies ranging from 42.5 to 55.0 MeV in 2.5 MeV steps. The total reaction cross sections were derived from the measured angular distributions by using an optical model fit within the coupled-channel code FRESCO. These cross sections are very similar to those measured for 17F (loosely bound by 0.6 MeV), mirror nucleus of 17O (tightly bound by 4.14 MeV). This outcome points out that, in this energy range, the small binding energy of the 17F valence proton has negligible influence onto the reactivity of such a loosely bound projectile, contrary to simple expectations, and to what observed for other loosely bound nuclei. The reaction dynamics seems to be influenced mainly by the Coulomb interaction which is similar for both mirror projectiles.

  18. New calculations and measurements of the Coulomb cross-section for the production of direct electron pairs by high energy nuclei

    NASA Technical Reports Server (NTRS)

    Derrickson, J. H.; Dake, S.; Dong, B. L.; Eby, P. B.; Fountain, W. F.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Iyono, A.; King, D. T.

    1989-01-01

    Recently, new calculations were made of the direct Coulomb pair cross section that rely less in arbitrary parameters. More accurate calculations of the cross section down to low pair energies were made. New measurements of the total direct electron pair yield, and the energy and angular distribution of the electron pairs in emulsion were made for O-16 at 60 and 200 GeV/amu at S-32 at 200 GeV/amu which give satisfactory agreement with the new calculations. These calculations and measurements are presented along with previous accelerator measurements made of this effect during the last 40 years. The microscope scanning criteria used to identify the direct electron pairs is described. Prospects for application of the pair method to cosmic ray energy measurements in the region 10 (exp 13) to 10 (exp 15) eV/amu are discussed.

  19. Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method

    NASA Astrophysics Data System (ADS)

    Kurashige, Yuki; Nakajima, Takahito; Sato, Takeshi; Hirao, Kimihiko

    2010-06-01

    We propose an efficient method for evaluating the Coulomb force in the Gaussian and finite-element Coulomb (GFC) method, which is a linear-scaling approach for evaluating the Coulomb matrix and energy in large molecular systems. The efficient evaluation of the analytical gradient in the GFC is not straightforward as well as the evaluation of the energy because the SCF procedure with the Coulomb matrix does not give a variational solution for the Coulomb energy. Thus, an efficient approximate method is alternatively proposed, in which the Coulomb potential is expanded in the Gaussian and finite-element auxiliary functions as done in the GFC. To minimize the error in the gradient not just in the energy, the derived functions of the original auxiliary functions of the GFC are used additionally for the evaluation of the Coulomb gradient. In fact, the use of the derived functions significantly improves the accuracy of this approach. Although these additional auxiliary functions enlarge the size of the discretized Poisson equation and thereby increase the computational cost, it maintains the near linear scaling as the GFC and does not affects the overall efficiency of the GFC approach.

  20. Dielectric-dependent screened Hartree-Fock exchange potential and Slater-formula with Coulomb-hole interaction for energy band structure calculations.

    PubMed

    Shimazaki, Tomomi; Nakajima, Takahito

    2014-09-21

    We previously reported a screened Hartree-Fock (HF) exchange potential for energy band structure calculations [T. Shimazaki and Y. Asai, J. Chem. Phys. 130, 164702 (2009); T. Shimazaki and Y. Asai, J. Chem. Phys. 132, 224105 (2010)]. In this paper, we discuss the Coulomb-hole (COH) interaction and screened Slater-formula and determine the energy band diagrams of several semiconductors, such as diamond, silicon, AlAs, AlP, GaAs, GaP, and InP, based on the screened HF exchange potential and Slater-formula with COH interaction, to demonstrate the adequacy of those theoretical concepts. The screened HF exchange potential and Slater-formula are derived from a simplified dielectric function and, therefore, include the dielectric constant in their expressions. We also present a self-consistent calculation technique to automatically determine the dielectric constant, which is incorporated into each self-consistent field step. PMID:25240347

  1. Dielectric-dependent screened Hartree-Fock exchange potential and Slater-formula with Coulomb-hole interaction for energy band structure calculations

    NASA Astrophysics Data System (ADS)

    Shimazaki, Tomomi; Nakajima, Takahito

    2014-09-01

    We previously reported a screened Hartree-Fock (HF) exchange potential for energy band structure calculations [T. Shimazaki and Y. Asai, J. Chem. Phys. 130, 164702 (2009); T. Shimazaki and Y. Asai, J. Chem. Phys. 132, 224105 (2010)]. In this paper, we discuss the Coulomb-hole (COH) interaction and screened Slater-formula and determine the energy band diagrams of several semiconductors, such as diamond, silicon, AlAs, AlP, GaAs, GaP, and InP, based on the screened HF exchange potential and Slater-formula with COH interaction, to demonstrate the adequacy of those theoretical concepts. The screened HF exchange potential and Slater-formula are derived from a simplified dielectric function and, therefore, include the dielectric constant in their expressions. We also present a self-consistent calculation technique to automatically determine the dielectric constant, which is incorporated into each self-consistent field step.

  2. Coulomb Glass: a Mean Field Study

    NASA Astrophysics Data System (ADS)

    Mandra, Salvatore; Palassini, Matteo

    2012-02-01

    We study the Coulomb glass model of disordered localized electrons with long-range Coulomb interaction, which describes systems such as disordered insulators, granular metals, amorphous semiconductors, or doped crystalline semiconductors. Long ago Efros and Shklovskii showed that the long-range repulsion induces a soft Coulomb gap in the single particle density of states at low temperatures. Recent works suggested that this gap is associated to a transition to a glass phase, similar to the Almeida-Thouless transition in spin glasses. In this work, we use a mean field approach to characterize several physical properties of the Coulomb glass. In particular, following a seminal work of Bray and Moore, we show that the Edward-Anderson parameter qEA and the spin glass susceptibility χSG are directly related to spectrum distribution of the Hessian matrix around free energy minima. Using this result, we show that no glass transition is associated to the gap formation.

  3. One- and two-nucleon transfer in the {sup 28} Si+{sup 68}Zn system at energies below the Coulomb barrier

    SciTech Connect

    Kataria, D.O.; Sinha, A.K.; Das, J.J.; Madhavan, N.; Sugathan, P.; Baby, L.T.; Mazumdar, I.; Singh, R.; Baba, C.V.; Agarwal, Y.K.; Vinodkumar, A.M.; Varier, K.M.

    1997-10-01

    Excitation functions for one- and two-nucleon transfer in {sup 28}Si + {sup 68}Zn system have been measured at energies below the Coulomb barrier. The experiment was carried out by detecting the forward recoiling targetlike nuclei using the recoil mass separator, HIRA. With a pulsed beam, the time-of-flight of the recoils was measured and used to resolve the M/q ambiguity. This enabled the determination of the two-nucleon transfer yields. The role of one- and two-nucleon transfer in the sub-barrier fusion cross-section enhancement has been investigated. It turns out that the coupling of the positive Q-value two-neutron transfer channel results in a significant contribution to the enhancement. Coupling to both the transfer and the inelastic channels is able to explain the observed enhancement. {copyright} {ital 1997} {ital The American Physical Society}

  4. Giant Coulomb blockade magnetoresistance

    SciTech Connect

    Zhang, Xiaoguang; Wen, Z. C.; Wei, H. X.; Han, Prof. X. F.

    2010-01-01

    We show that the Coulomb blockade voltage can be made to depend strongly on the electron spin in a thin magnetic granular layer inserted in the middle of an insulating layer of a tunnel junction. This strong spin dependence is predicted from the spin-dependent inter-granular conductance through any of the following effects within the granular layer, giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), colossal magnetoresistance (CMR), or GMR through a polymer spacer. The resulting Coulomb blockade magnetoresistance (CBMR) ratio can exceed the magnetoresistance ratio of the granular layer itself by orders of magnitude. Unlike other magenetoresistance effects, the CBMR effect does not require magnetic electrodes.

  5. Confinement of Coulomb balls

    SciTech Connect

    Arp, O.; Block, D.; Klindworth, M.; Piel, A.

    2005-12-15

    A model for the confinement of the recently discovered Coulomb balls is proposed. These spherical three-dimensional plasma crystals are trapped inside a rf discharge under gravity conditions and show an unusual structural order in complex plasmas. Measurements of the thermophoretic force acting on the trapped dust particles and simulations of the plasma properties of the discharge are presented. The proposed model of confinement considers thermophoretic, ion-drag, and electric field forces, and shows excellent agreement with the observations. The findings suggest that self-confinement does not significantly contribute to the structural properties of Coulomb balls.

  6. Astrophysical S(E) factor of the {sup 15}N(p,{alpha}){sup 12}C reaction at sub-Coulomb energies via the Trojan horse method

    SciTech Connect

    La Cognata, M.; Romano, S.; Spitaleri, C.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Pizzone, R. G.; Tumino, A.; Tribble, R.; Fu, Changbo; Goldberg, V. Z.; Mukhamedzhanov, A. M.; Schmidt, D.; Tabacaru, G.; Trache, L.; Irgaziev, B. F.

    2007-12-15

    The low-energy bare-nucleus cross section for {sup 15}N(p,{alpha}){sup 12}C is extracted by means of the Trojan horse method applied to the {sup 2}H({sup 15}N,{alpha}{sup 12}C)n reaction at E{sub beam}=60 MeV. For the first time we applied the modified half-off-energy-shell resonant R-matrix method that takes into account off-energy-shell effects and initial- and final-state interactions. In particular it has been shown that inclusion of Coulomb {sup 15}N-d scattering and off-shell effects do not affect the determination of the astrophysical factor. Also the simple plane-wave approximation used in previous analyses is justified. The results extracted via the Trojan horse method are compared to direct data in the same energy region and show very good agreement in the energy interval 70-312 keV. These results confirm the extrapolations of the S factor reported in literature.

  7. Development of the Silicon Array at Notre Dame (SAND) for the Study of the 12C + 12C Reaction at Sub-Coulomb Energies

    NASA Astrophysics Data System (ADS)

    Cahillane, Craig

    2011-10-01

    The 12C + 12C fusion reaction is an important process in stellar evolution and nucleosynthesis. The energy region of interest lies between 1 and 3 MeV, but studying the reaction at these energies is difficult because of the reaction's rapidly decaying cross-section a sub-Coulomb energies. Both detector efficiency and beam intensity limit such measurements. As a test run for the future Silicon Array at Notre Dame (SAND), two YY1 Trapezoid Silicon Detectors were used to detect the proton decay of the carbon fusion reaction. The two detectors covered a solid angle of 0.34 steradians. In the construction of SAND, more large surface area silicon detectors will be used to dramatically increase detection efficiency by covering a much larger solid angle. Combined with the new high-intensity 5 MV accelerator also under construction at Notre Dame, SAND could reduce the error on low energy cross sections in the astrophysical region and possibly detect hypothesized resonances at lower energies. This work is supported by the NSF under Grant No. PHY-1068192 and PHY-0822648.

  8. Dynamical effects in the Coulomb expansion following nuclear fragmentation

    SciTech Connect

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

    1987-09-01

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

  9. Measuring the Fusion Cross-Section of 18,19 O + 12 C with Low-Intensity Beams at Energies Near and Below the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Steinbach, Tracy; Vadas, Justin; Schmidt, Jon; Singh, Varinderjit; Hudan, Sylvie; Desouza, Romualdo; Baby, Lagy; Kuvin, Sean; Wiedenhover, Ingo; Umar, Sait; Oberacker, Volker

    2015-04-01

    Fusion of neutron-rich light nuclei has been proposed as a heat source that triggers an X-ray superburst in the crust of an accreting neutron star. To investigate this hypothesis the total fusion cross-section for beams of low-intensity, neutron-rich nuclei (<105 ions/s) on light targets has been measured at energies near and below the Coulomb barrier. Evaporation residues, resulting from the fusion of oxygen and 12 C nuclei, were identified by their energy and Time-of-flight. Using this technique, the fusion excitation function was measured in the sub-barrier domain down to the 2 mb level. Comparison of the measured fusion excitation function with the predictions of a density constrained TDHF model reveals that the experimental data exhibit a smaller decrease in cross-section with decreasing energy than is theoretically predicted. This difference can be interpreted as a larger tunneling probability for the experimental data as compared to the theoretical predictions. To determine if this difference increases in magnitude with decreasing incident energy improvements have been implemented to enable measurement of the fusion cross-section to an even lower level. Supported by the US DOE under Grand No. DEFG02-88ER-40404.

  10. Coulomb Breakup Problem

    SciTech Connect

    Kadyrov, A. S.; Bray, I.; Stelbovics, A. T.; Mukhamedzhanov, A. M.

    2008-12-05

    We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the three-body wave functions. This formulation is valid for both short-range and Coulombic potentials. The post and prior forms of the breakup amplitude are derived without any reference to renormalization procedures.

  11. Coulomb problem for vector bosons

    SciTech Connect

    Kuchiev, M.Yu.; Flambaum, V.V.

    2006-05-01

    The Coulomb problem for vector bosons W{sup {+-}} incorporates a well-known difficulty; the charge of the boson localized in a close vicinity of the attractive Coulomb center proves to be infinite. The paradox is shown to be resolved by the QED vacuum polarization, which brings in a strong effective repulsion that eradicates the infinite charge of the boson on the Coulomb center. This property allows one to define the Coulomb problem for vector bosons properly.

  12. New approach to folding with the Coulomb wave function

    SciTech Connect

    Blokhintsev, L. D.; Savin, D. A.; Kadyrov, A. S.; Mukhamedzhanov, A. M.

    2015-05-15

    Due to the long-range character of the Coulomb interaction theoretical description of low-energy nuclear reactions with charged particles still remains a formidable task. One way of dealing with the problem in an integral-equation approach is to employ a screened Coulomb potential. A general approach without screening requires folding of kernels of the integral equations with the Coulomb wave. A new method of folding a function with the Coulomb partial waves is presented. The partial-wave Coulomb function both in the configuration and momentum representations is written in the form of separable series. Each term of the series is represented as a product of a factor depending only on the Coulomb parameter and a function depending on the spatial variable in the configuration space and the momentum variable if the momentum representation is used. Using a trial function, the method is demonstrated to be efficient and reliable.

  13. Coulomb Dissociation of 27P

    NASA Astrophysics Data System (ADS)

    Beceiro Novo, S.; Sümmerer, K.; Cortina-Gil, D.; Wimmer, C.; Plag, R.; Alvarez-Pol, H.; Aumann, T.; Behr, K.; Boretzky, K.; Casarejos, E.; Chatillon, A.; Datta-Pramanik, U.; Elekes, Z.; Fulop, Z.; Galaviz, D.; Geissel, H.; Giron, S.; Greife, U.; Hammache, F.; Heil, M.; Hoffman, J.; Johansson, H.; Karagiannis, C.; Kiselev, O.; Kurz, N.; Larsson, K.; Le Bleis, T.; Litvinov, Y.; Mahata, K.; Muentz, C.; Nociforo, C.; Ott, W.; Paschalis, S.; Prokopowicz, W.; Rodriguez-Tajes, C.; Rossi, D.; Simon, H.; Stanoiu, M.; Stroth, J.; Typel, S.; Wagner, A.; Wamers, F.; Weick, H.

    2012-09-01

    In this work the astrophysical 26Si(p,γ)27P reaction is studied using the Coulomb dissociation technique. We performed a 27P Coulomb Dissociation experiment at GSI, Darmstadt (28 May-5 June 2007) using the ALADIN-LAND setup which allows complete-kinematic studies. A secondary 27P beam at 498 AMeV impinging a 515mg/cm2 Pb target was used. The relative energy of the outgoing system (26Si+p) is measured obtaining the resonant states of the 27P. Preliminary results show four resonant states measured at 0.36±0.07, 0.88±0.09, 1.5±0.2, 2.3±0.3 MeV and evidence of a higher state at around 3.1 MeV. The preliminary total cross section obtained for relative energies between 0 and 3 MeV has been measured and yields 55±7 mb.

  14. High-energy Coulomb breakup of proton-dripline nuclei as a tool to study radiative-capture reactions of astrophysical interest

    NASA Astrophysics Data System (ADS)

    Sümmerer, K.

    2007-11-01

    High-energy Coulomb dissociation (CD) can be used to investigate the time-reversed process, radiative capture, for unstable nuclei where the direct capture reaction is difficult or impossible to perform. At GSI, we have run a series of CD measurements involving the proton-halo nucleus 8B which plays a major role in solar-neutrino physics. We could show that for this case CD and direct proton capture yield the same result. Theoretical guidance is necessary, however, to make sure that contributions of different electro-magnetic multipolarities and nuclear dissociation processes are well under control. Recently, we have complemented the LAND/ALADIN experimental apparatus at GSI with new Si microstrip detectors and proton-drift-chambers to continue similar studies with radioactive beams from the fragment separator FRS at GSI. The first case of astrophysical interest to be studied will be the CD of 27P. Another case will be the 2-proton breakup of 17Ne to investigate radiative two-proton capture on 15O, a process which could modify the reaction flow of the rp-process.

  15. Coulomb interaction energy including overlap effects for the ground states of LiNa and Na 2

    NASA Astrophysics Data System (ADS)

    Bussery, B.; Achkar, Y.; Aubert-Frécon, M.

    1989-01-01

    A recently proposed method to calculate first-order electrostatic as well as second-order induction and dispersion energies including charge-overlap effects for the interaction between two atoms each with one active electron is applied to the systems Li(2s) + Na(3s) and Na(3s) + Na(3s), giving the induction energy for both systems. The variation with R of the relative contribution of the overlapping and non-overlapping configuration space regions is discussed for the largest dispersion and induction terms.

  16. An exchange-Coulomb model potential energy surface for the Ne-CO interaction. II. Molecular beam scattering and bulk gas phenomena in Ne-CO mixtures.

    PubMed

    Dham, Ashok K; McBane, George C; McCourt, Frederick R W; Meath, William J

    2010-01-14

    Four potential energy surfaces are of current interest for the Ne-CO interaction. Two are high-level fully ab initio surfaces obtained a decade ago using symmetry-adapted perturbation theory and supermolecule coupled-cluster methods. The other two are very recent exchange-Coulomb (XC) model potential energy surfaces constructed by using ab initio Heitler-London interaction energies and literature long range dispersion and induction energies, followed by the determination of a small number of adjustable parameters to reproduce a selected subset of pure rotational transition frequencies for the (20)Ne-(12)C(16)O van der Waals cluster. Testing of the four potential energy surfaces against a wide range of available experimental microwave, millimeter-wave, and mid-infrared Ne-CO transition frequencies indicated that the XC potential energy surfaces gave results that were generally far superior to the earlier fully ab initio surfaces. In this paper, two XC model surfaces and the two fully ab initio surfaces are tested for their abilities to reproduce experiment for a wide range of nonspectroscopic Ne-CO gas mixture properties. The properties considered here are relative integral cross sections and the angle dependence of rotational state-to-state differential cross sections, rotational relaxation rate constants for CO(v=2) in Ne-CO mixtures at T=296 K, pressure broadening of two pure rotational lines and of the rovibrational lines in the CO fundamental and first overtone transitions at 300 K, and the temperature and, where appropriate, mole fraction dependencies of the interaction second virial coefficient, the binary diffusion coefficient, the interaction viscosity, the mixture shear viscosity and thermal conductivity coefficients, and the thermal diffusion factor. The XC model potential energy surfaces give results that lie within or very nearly within the experimental uncertainties for all properties considered, while the coupled-cluster ab initio surface gives

  17. Ion Coulomb crystals

    NASA Astrophysics Data System (ADS)

    Drewsen, Michael

    2015-03-01

    The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged the past two decades. While this document lacks figures, it includes a substantial number of references in which more detailed information can be found. It is the hope that the text will stimulate the reader to dig deeper into one or more of the discussed subjects and inspire her/him to think about new potential applications.

  18. Semiclassical Coulomb field

    SciTech Connect

    Polonyi, J.

    2008-06-15

    The contribution of different modes of the Coulomb field to decoherence and to the dynamical breakdown of the time reversal invariance is calculated in the one-loop approximation for nonrelativistic electron gas. The dominant contribution was found to come from the usual collective modes in the plasma, namely, the zero-sound and the plasmon oscillations. The length scale of the quantum-classical transition is found to be close to the Thomas-Fermi screening length. It is argued that the extension of these modes to the whole Fock space yields optimal pointer states.

  19. Plane Wave and Coulomb Asymptotics

    NASA Astrophysics Data System (ADS)

    Mulligan, P. G.; Crothers, D. S. F.

    2004-01-01

    A simple plane wave solution of the Schrödinger Helmholtz equation is a quantum eigenfunction obeying both energy and linear momentum correspondence principles. Inclusion of the outgoing wave with scattering amplitude f obeys unitarity and the optical theorem. By closely considering the standard asymptotic development of the plane wave, we show that there is a problem with angular momentum when we consider forward scattering at the point of closest approach and at large impact parameter given semiclassically by (l + 1/2)/k where l is the azimuthal quantum number and may be large (J Leech et al, Phys. Rev. Lett. 88 257901 (2002)). The problem is resolved via non-uniform, non-standard analysis involving the Heaviside step function, unifying classical, semiclassical and quantum mechanics, and the treatment is extended to the case of pure Coulomb scattering.

  20. Elastic and inelastic angular distributions of the 7Li+120Sn system for energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Zagatto, V. A. B.; Oliveira, J. R. B.; Gasques, L. R.; Alcántara-Núñez, J. A.; Duarte, J. G.; Aguiar, V. P.; Medina, N. H.; Seale, W. A.; Pires, K. C. C.; Freitas, A.; Lubian, J.; Shorto, J. M. B.; Genezini, F. A.; Rossi, E. S., Jr.

    2016-06-01

    The reaction of 7Li+120Sn has been measured at bombarding energies of 21, 24 and 27 MeV. The {2}+\\to {0}+ γ -ray transition in 120Sn was observed and the angular distribution for the 2+ excited state was obtained. Coupled channels and coupled-reaction channels calculations, including the dynamical polarization potential due to the projectile break-up, obtained from continuum discretized coupled channel calculations, were performed. The comparison between the existing experimental elastic angular distribution with the coupled-reaction channels calculations indicates that the 1n stripping transfer is the most intense channel to be coupled and the 2n stripping reaction occurs sequentially rather than directly, however, further data must be analyzed to confirm this indication. The experimental elastic and inelastic scattering data were well described by the calculations, but some discrepancies in these channels may indicate the need for corrections to the nuclear potential and/or the necessity to incorporate further channels.

  1. Investigation of complete and incomplete fusion dynamics of {sup 20}Ne induced reactions at energies above the Coulomb barrier

    SciTech Connect

    Singh, D.; Ali, R.; Kumar, Harish; Ansari, M. Afzal; Rashid, M. H.; Guin, R.

    2014-08-14

    Experiment has been performed to explore the complete and incomplete fusion dynamics in heavy ion collisions using stacked foil activation technique. The measurement of excitation functions of the evaporation residues produced in the {sup 20}Ne+{sup 165}Ho system at projectile energies ranges ≈ 4-8 MeV/nucleon have been done. Measured cumulative and direct cross-sections have been compared with the theoretical model code PACE-2, which takes into account only the complete fusion process. The analysis indicates the presence of contributions from incomplete fusion processes in some α-emission channels following the break-up of the projectile {sup 20}Ne in the nuclear field of the target nucleus {sup 165}Ho.

  2. PREFACE: Strongly Coupled Coulomb Systems

    NASA Astrophysics Data System (ADS)

    Fortov, Vladimir E.; Golden, Kenneth I.; Norman, Genri E.

    2006-04-01

    This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) which was held during the week of 20 24 June 2005 in Moscow, Russia. The Moscow conference was the tenth in a series of conferences. The previous conferences were organized as follows. 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (organized by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (organized by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, NY, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) After 1995 the name of the series was changed from `Strongly Coupled Plasmas' to the present name in order to extend the topics of the conferences. The planned frequency for the future is once every three years. The purpose of these conferences is to provide an international forum for the presentation and discussion of research accomplishments and ideas relating to a variety of plasma liquid and condensed matter systems, dominated by strong Coulomb interactions between their constituents. Strongly coupled Coulomb systems encompass diverse many-body systems and physical conditions. Each meeting has seen an evolution of topics and emphasis as new discoveries and new methods appear. This year, sessions were organized for invited presentations and posters on dense plasmas and warm matter, astrophysics and dense hydrogen, non-neutral and ultracold plasmas, dusty plasmas, condensed matter 2D and layered charged-particle systems, Coulomb liquids, and statistical theory of SCCS. Within

  3. Boltzmann-Langevin theory of Coulomb drag

    NASA Astrophysics Data System (ADS)

    Chen, W.; Andreev, A. V.; Levchenko, A.

    2015-06-01

    We develop a Boltzmann-Langevin description of the Coulomb drag effect in clean double-layer systems with large interlayer separation d as compared to the average interelectron distance λF. Coulomb drag arises from density fluctuations with spatial scales of order d . At low temperatures, their characteristic frequencies exceed the intralayer equilibration rate of the electron liquid, and Coulomb drag may be treated in the collisionless approximation. As temperature is raised, the electron mean free path becomes short due to electron-electron scattering. This leads to local equilibration of electron liquid, and consequently drag is determined by hydrodynamic density modes. Our theory applies to both the collisionless and the hydrodynamic regimes, and it enables us to describe the crossover between them. We find that drag resistivity exhibits a nonmonotonic temperature dependence with multiple crossovers at distinct energy scales. At the lowest temperatures, Coulomb drag is dominated by the particle-hole continuum, whereas at higher temperatures of the collision-dominated regime it is governed by the plasmon modes. We observe that fast intralayer equilibration mediated by electron-electron collisions ultimately renders a stronger drag effect.

  4. Poisson's equation solution of Coulomb integrals in atoms and molecules

    NASA Astrophysics Data System (ADS)

    Weatherford, Charles A.; Red, Eddie; Joseph, Dwayne; Hoggan, Philip

    The integral bottleneck in evaluating molecular energies arises from the two-electron contributions. These are difficult and time-consuming to evaluate, especially over exponential type orbitals, used here to ensure the correct behaviour of atomic orbitals. In this work, it is shown that the two-centre Coulomb integrals involved can be expressed as one-electron kinetic-energy-like integrals. This is accomplished using the fact that the Coulomb operator is a Green's function of the Laplacian. The ensuing integrals may be further simplified by defining Coulomb forms for the one-electron potential satisfying Poisson's equation therein. A sum of overlap integrals with the atomic orbital energy eigenvalue as a factor is then obtained to give the Coulomb energy. The remaining questions of translating orbitals involved in three and four centre integrals and the evaluation of exchange energy are also briefly discussed. The summation coefficients in Coulomb forms are evaluated using the LU decomposition. This algorithm is highly parallel. The Poisson method may be used to calculate Coulomb energy integrals efficiently. For a single processor, gains of CPU time for a given chemical accuracy exceed a factor of 40. This method lends itself to evaluation on a parallel computer.

  5. Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures.

    PubMed

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-05-13

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)-a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems. PMID:27232031

  6. Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures

    NASA Astrophysics Data System (ADS)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-05-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)—a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems.

  7. Feynman rules for Coulomb gauge QCD

    SciTech Connect

    Andrasi, A.; Taylor, J.C.

    2012-10-15

    The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel. - Highlights: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.

  8. Positron scattering from hydrogen atom with screened Coulomb potentials

    SciTech Connect

    Ghoshal, Arijit; Nayek, Sujay; Kamali, M. Z. M.; Ratnavelu, K.

    2014-03-05

    Elastic positron-hydrogen collisions with screened Coulomb potentials have been investigated using a second-order distorted wave Born approximation in the momentum space. Two types of potentials have been considered, namely, static screened Coulomb potential and exponential cosine-screened Coulomb potential. Using a simple variationally determined hydrogenic wave function it has been possible to obtain the scattering amplitude in a closed form. A detailed study has been made on the differential and total cross sections in the energy range 20–300 eV.

  9. Coulomb interactions and fermion condensation

    SciTech Connect

    Capstick, S.; Cutkosky, R.E.; Joensen, M.A. ); Wang, K.C. )

    1990-08-15

    The influence of the Coulomb interaction in states containing massless and flavorless fermion-antifermion pairs is studied, using a continuum formulation within the finite volume {ital S}{sup 3}. Several different forms for the Coulomb interaction are examined, including confining potentials as well as nonconfining potentials. The calculations show that if the interaction is strong enough, the Coulomb interaction leads to condensation of pairs, and that this condensation has a chiral character. The condensation does not depend on whether the interaction is confining. It is found that simplified variational approximations are not accurate enough for an adequate description of the states.

  10. Thermodynamic properties of the magnetized Coulomb crystal lattices

    NASA Astrophysics Data System (ADS)

    Kozhberov, A. A.

    2016-08-01

    It is thought that Coulomb crystals of ions with hexagonal close-packed lattice may form in the crust of strongly-magnetized neutron stars (magnetars). In this work we are trying to verify this prediction assuming that the direction of the magnetic field corresponds to the minimum of the zero-point energy. We also continue a detailed study of vibration modes and thermodynamic properties of magnetized Coulomb crystals in a wide range of temperatures and magnetic fields. It is demonstrated that the total Helmholtz free energy of the body-centered cubic Coulomb crystal is always lower than that of the Coulomb crystal with hexagonal close-packed or face-centered cubic lattice, which casts doubt on the hypothesis above.

  11. An Application of the Direct Coulomb Electron Pair Production Process to the Energy Measurement of the "VH-Group" in the "Knee" Region of the "All-Particle" Energy Spectrum

    NASA Technical Reports Server (NTRS)

    Derrickson, J. H.; Wu, J.; Christl, M. J.; Fountain, W. F.; Parnell, T. A.

    1999-01-01

    The "all-particle" cosmic ray energy spectrum appears to be exhibiting a significant change in the spectral index just above approximately 3000 TeV. This could indicate (1) a change in the propagation of the cosmic rays in the galactic medium, and/or (2) the upper limit of the supernova shock wave acceleration mechanism, and/or (3) a new source of high-energy cosmic rays. Air shower and JACEE data indicate the spectral change is associated with a composition change to a heavier element mixture whereas DICE does not indicate this. A detector concept will be presented that utilizes the energy dependence of the production of direct Coulomb electron-positron pairs by energetic heavy ions. Monte Carlo simulations of a direct electron pair detector consisting of Pb target foils interleaved with planes of 1-mm square scintillating optical fibers will be discussed. The goal is to design a large area, non-saturating instrument to measure the energy spectrum of the individual cosmic ray elements in the "VH-group" for energies greater than 10 TeV/nucleon.

  12. Analysis and results of the 104Sn Coulomb excitation experiment

    NASA Astrophysics Data System (ADS)

    Guastalla, G.; DiJulio, D. D.; Górska, M.; Cederkäll, J.; Boutachkov, P.; Golubev, P.; Pietri, S.; Grawe, H.; Nowacki, F.; Algora, A.; Ameil, F.; Arici, T.; Atac, A.; Bentley, M. A.; Blazhev, A.; Bloor, D.; Brambilla, S.; Braun, N.; Camera, F.; Domingo Pardo, C.; Estrade, A.; Farinon, F.; Gerl, J.; Goel, N.; Grȩbosz, J.; Habermann, T.; Hoischen, R.; Jansson, K.; Jolie, J.; Jungclaus, A.; Kojouharov, I.; Knoebel, R.; Kumar, R.; Kurcewicz, J.; Kurz, N.; Lalović, N.; Merchan, E.; Moschner, K.; Naqvi, F.; Nara Singh, B. S.; Nyberg, J.; Nociforo, C.; Obertelli, A.; Pfützner, M.; Pietralla, N.; Podolyák, Z.; Prochazka, A.; Ralet, D.; Reiter, P.; Rudolph, D.; Schaffner, H.; Schirru, F.; Scruton, L.; Swaleh, T.; Taprogge, J.; Wadsworth, R.; Warr, N.; Weick, H.; Wendt, A.; Wieland, O.; Winfield, J. S.; Wollersheim, H. J.

    2014-09-01

    The analysis of the Coulomb excitation experiment conducted on 104Sn required a strict selection of the data in order to reduce the large background present in the γ-ray energy spectra and identify the γ-ray peak corresponding to the Coulomb excitation events. As a result the B(E2; 0+ → 2+) value could be extracted, which established the downward trend towards 100Sn and therefore the robustness of the N=Z=50 core against quadrupole excitations.

  13. Dynamics of Coulombic and gravitational periodic systems.

    PubMed

    Kumar, Pankaj; Miller, Bruce N

    2016-04-01

    We study the dynamics and the phase-space structures of Coulombic and self-gravitating versions of the classical one-dimensional three-body system with periodic boundary conditions. We demonstrate that such a three-body system may be reduced isomorphically to a spatially periodic system of a single particle experiencing a two-dimensional potential on a rhombic plane. For the case of both Coulombic and gravitational versions, exact expressions of the Hamiltonian have been derived in rhombic coordinates. We simulate the phase-space evolution through an event-driven algorithm that utilizes analytic solutions to the equations of motion. The simulation results show that the motion exhibits chaotic, quasiperiodic, and periodic behaviors in segmented regions of the phase space. While there is no evidence of global chaos in either the Coulombic or the gravitational system, the former exhibits a transition from a completely nonchaotic phase space at low energies to a mixed behavior. Gradual yet striking transitions from mild to intense chaos are indicated with changing energy, a behavior that differentiates the spatially periodic systems studied in this Rapid Communication from the well-understood free-boundary versions of the three-body problem. Our treatment of the three-body systems opens avenues for analysis of the dynamical properties exhibited by spatially periodic versions of various classes of systems studied in plasma and gravitational physics as well as in cosmology. PMID:27176238

  14. Dynamics of Coulombic and gravitational periodic systems

    NASA Astrophysics Data System (ADS)

    Kumar, Pankaj; Miller, Bruce N.

    2016-04-01

    We study the dynamics and the phase-space structures of Coulombic and self-gravitating versions of the classical one-dimensional three-body system with periodic boundary conditions. We demonstrate that such a three-body system may be reduced isomorphically to a spatially periodic system of a single particle experiencing a two-dimensional potential on a rhombic plane. For the case of both Coulombic and gravitational versions, exact expressions of the Hamiltonian have been derived in rhombic coordinates. We simulate the phase-space evolution through an event-driven algorithm that utilizes analytic solutions to the equations of motion. The simulation results show that the motion exhibits chaotic, quasiperiodic, and periodic behaviors in segmented regions of the phase space. While there is no evidence of global chaos in either the Coulombic or the gravitational system, the former exhibits a transition from a completely nonchaotic phase space at low energies to a mixed behavior. Gradual yet striking transitions from mild to intense chaos are indicated with changing energy, a behavior that differentiates the spatially periodic systems studied in this Rapid Communication from the well-understood free-boundary versions of the three-body problem. Our treatment of the three-body systems opens avenues for analysis of the dynamical properties exhibited by spatially periodic versions of various classes of systems studied in plasma and gravitational physics as well as in cosmology.

  15. Fast and accurate Coulomb calculation with Gaussian functions.

    PubMed

    Füsti-Molnár, László; Kong, Jing

    2005-02-15

    Coulomb interaction is one of the major time-consuming components in a density functional theory (DFT) calculation. In the last decade, dramatic progresses have been made to improve the efficiency of Coulomb calculation, including continuous fast multipole method (CFMM) and J-engine method, all developed first inside Q-Chem. The most recent development is the advent of Fourier transform Coulomb method developed by Fusti-Molnar and Pulay, and an improved version of the method has been recently implemented in Q-Chem. It replaces the least efficient part of the previous Coulomb methods with an accurate numerical integration scheme that scales in O(N2) instead of O(N4) with the basis size. The result is a much smaller slope in the linear scaling with respect to the molecular size and we will demonstrate through a series of benchmark calculations that it speeds up the calculation of Coulomb energy by several folds over the efficient existing code, i.e., the combination of CFMM and J-engine, without loss of accuracy. Furthermore, we will show that it is complementary to the latter and together the three methods offer the best performance for Coulomb part of DFT calculations, making the DFT calculations affordable for very large systems involving thousands of basis functions. PMID:15743222

  16. Efros-Shklovskii variable range hopping conductivity without Coulomb gap

    NASA Astrophysics Data System (ADS)

    Chen, Tianran; Skinner, Brian

    In doped semiconductors and Coulomb glasses, in the limit of weak coupling, the electron conductivity primarily proceeds by phonon-assisted tunneling or hopping between different sites through the insulating gaps that separate them. Electron conduction can occur both through nearest-neighbor hopping and through cotunneling of electrons between distant sites via a chain of intermediate virtual states. In the presence of some disorder, the latter mechanism dominates at low temperatures, where the length of the hops grows to optimize the conductivity. This transport mechanism was introduced by Mott, and is called variable range hopping. When the Coulomb interaction between localized electrons is taken into account, it can be shown that at a sufficiently low temperature, variable range hopping conductivity obeys the Efros-Shklovskii (ES) law, which has been observed in a number of amorphous semiconductors and granular metal systems at low temperatures. ES conductivity has been long understood as the result of a soft, Coulomb gap at the Fermi level. However, such a theory overlooks the presence of spatial correlations between site energies and their possible effects on electrical conductivity. In this talk, we show both analytically and numerically that in systems where spatial correlations must be taken into account, ES conductivity may persist far outside the Coulomb gap, in contrast to conventional transport theory for doped semiconductors and Coulomb glasses where ES conductivity only occurs within the Coulomb gap.

  17. Studies of Coulomb Gauge QCD

    SciTech Connect

    Adam P. Szczepaniak; Eric S. Swanson

    2000-12-12

    Here we will discuss how the nonabelian Coulomb kernel exhibits confinement already at the mean field level. In the heavy quark limit residual interactions between heavy quarks and transverse gluons are spin dependent i.e., relativistic and can be calculated using the Foldy-Wouthuysen transformation. This makes the Coulomb gauge suitable for studying the nonrelativistic limit. Finally it is possible to use standard mean field techniques to define quasiparticle excitations, which, as we discuss below, have similar properties to what is usually assumed about constituent quarks in the light quark sector.

  18. Energy dependence of the optical potentials for the 9Be +208Pb and 9Be +209Bi systems at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Yu, N.; Zhang, H. Q.; Gomes, P. R. S.; Jia, H. M.; Lubian, J.; Lin, C. J.

    2015-04-01

    We analyze the energy dependence of the interacting optical potential, at near barrier energies, for two systems involving the weakly bound projectile 9Be and the heavy 208Pb and 209Bi targets, by the simultaneous fit of elastic scattering angular distributions and fusion excitation functions. The approach used consists of dividing the optical potential into two parts. A short-range potential VF+i WF that is responsible for fusion, and a superficial potential VDR+i WDR for direct reactions. It is found, for both systems studied, that the fusion imaginary potential WF presents the usual threshold anomaly (TA) observed in tightly bound systems, whereas the direct reaction imaginary potential WDR shows a breakup threshold anomaly (BTA) behavior. Both potentials satisfy the dispersion relation. The direct reaction polarization potential predominates over the fusion potential and so a net overall behavior is found to follow the BTA phenomenon.

  19. Feynman rules for Coulomb gauge QCD

    NASA Astrophysics Data System (ADS)

    Andraši, A.; Taylor, J. C.

    2012-10-01

    The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel.

  20. Negative Coulomb Drag in Double Bilayer Graphene.

    PubMed

    Li, J I A; Taniguchi, T; Watanabe, K; Hone, J; Levchenko, A; Dean, C R

    2016-07-22

    We report on an experimental measurement of Coulomb drag in a double quantum well structure consisting of bilayer-bilayer graphene, separated by few layer hexagonal boron nitride. At low temperatures and intermediate densities, a novel negative drag response with an inverse sign is observed, distinct from the momentum and energy drag mechanisms previously reported in double monolayer graphene. By varying the device aspect ratio, the negative drag component is suppressed and a response consistent with pure momentum drag is recovered. In the momentum drag dominated regime, excellent quantitative agreement with the density and temperature dependence predicted for double bilayer graphene is found. PMID:27494491

  1. Renormalization in Coulomb gauge QCD

    NASA Astrophysics Data System (ADS)

    Andraši, A.; Taylor, John C.

    2011-04-01

    In the Coulomb gauge of QCD, the Hamiltonian contains a non-linear Christ-Lee term, which may alternatively be derived from a careful treatment of ambiguous Feynman integrals at 2-loop order. We investigate how and if UV divergences from higher order graphs can be consistently absorbed by renormalization of the Christ-Lee term. We find that they cannot.

  2. Entropic Corrections to Coulomb's Law

    NASA Astrophysics Data System (ADS)

    Hendi, S. H.; Sheykhi, A.

    2012-04-01

    Two well-known quantum corrections to the area law have been introduced in the literatures, namely, logarithmic and power-law corrections. Logarithmic corrections, arises from loop quantum gravity due to thermal equilibrium fluctuations and quantum fluctuations, while, power-law correction appears in dealing with the entanglement of quantum fields in and out the horizon. Inspired by Verlinde's argument on the entropic force, and assuming the quantum corrected relation for the entropy, we propose the entropic origin for the Coulomb's law in this note. Also we investigate the Uehling potential as a radiative correction to Coulomb potential in 1-loop order and show that for some value of distance the entropic corrections of the Coulomb's law is compatible with the vacuum-polarization correction in QED. So, we derive modified Coulomb's law as well as the entropy corrected Poisson's equation which governing the evolution of the scalar potential ϕ. Our study further supports the unification of gravity and electromagnetic interactions based on the holographic principle.

  3. Equation of state for magnetized Coulomb plasmas

    NASA Astrophysics Data System (ADS)

    Potekhin, A. Y.; Chabrier, G.

    2013-02-01

    We have developed an analytical equation of state (EOS) for magnetized fully-ionized plasmas that cover a wide range of temperatures and densities, from low-density classical plasmas to relativistic, quantum plasma conditions. This EOS directly applies to calculations of structure and evolution of strongly magnetized white dwarfs and neutron stars. We review available analytical and numerical results for thermodynamic functions of the nonmagnetized and magnetized Coulomb gases, liquids, and solids. We propose a new analytical expression for the free energy of solid Coulomb mixtures. Based on recent numerical results, we have constructed analytical approximations for the thermodynamic functions of harmonic Coulomb crystals in quantizing magnetic fields. The analytical description ensures a consistent evaluation of all astrophysically important thermodynamic functions based on the first, second, and mixed derivatives of the free energy. Our numerical code for calculation of thermodynamic functions based on these approximations has been made publicly available. Using this code, we calculate and discuss the effects of electron screening and magnetic quantization on the position of the melting point in a range of densities and magnetic fields relevant to white dwarfs and outer envelopes of neutron stars. We consider also the thermal and mechanical structure of a magnetar envelope and argue that it can have a frozen surface which covers the liquid ocean above the solid crust. The Fortran code that realizes the analytical approximations described in this paper is available at http://www.ioffe.ru/astro/EIP/ and at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A43

  4. Fano effect dominance over Coulomb blockade in transport properties of parallel coupled quantum dot system

    SciTech Connect

    Brogi, Bharat Bhushan Ahluwalia, P. K.; Chand, Shyam

    2015-06-24

    Theoretical study of the Coulomb blockade effect on transport properties (Transmission Probability and I-V characteristics) for varied configuration of coupled quantum dot system has been studied by using Non Equilibrium Green Function(NEGF) formalism and Equation of Motion(EOM) method in the presence of magnetic flux. The self consistent approach and intra-dot Coulomb interaction is being taken into account. As the key parameters of the coupled quantum dot system such as dot-lead coupling, inter-dot tunneling and magnetic flux threading through the system can be tuned, the effect of asymmetry parameter and magnetic flux on this tuning is being explored in Coulomb blockade regime. The presence of the Coulomb blockade due to on-dot Coulomb interaction decreases the width of transmission peak at energy level ε + U and by adjusting the magnetic flux the swapping effect in the Fano peaks in asymmetric and symmetric parallel configuration sustains despite strong Coulomb blockade effect.

  5. Long-range Coulomb interaction in nodal-ring semimetals

    NASA Astrophysics Data System (ADS)

    Huh, Yejin; Moon, Eun-Gook; Kim, Yong Baek

    2016-01-01

    Recently there have been several proposals of materials predicted to be nodal-ring semimetals, where zero energy excitations are characterized by a nodal ring in the momentum space. This class of materials falls between the Dirac-like semimetals and the more conventional Fermi-surface systems. As a step towards understanding this unconventional system, we explore the effects of the long-range Coulomb interaction. Due to the vanishing density of states at the Fermi level, Coulomb interaction is only partially screened and remains long-ranged. Through renormalization group and large-Nf computations, we have identified a nontrivial interacting fixed point. The screened Coulomb interaction at the interacting fixed point is an irrelevant perturbation, allowing controlled perturbative evaluations of physical properties of quasiparticles. We discuss unique experimental consequences of such quasiparticles: acoustic wave propagation, anisotropic dc conductivity, and renormalized phonon dispersion as well as energy dependence of quasiparticle lifetime.

  6. Coulomb excitation studies of shape coexistence in atomic nuclei

    NASA Astrophysics Data System (ADS)

    Görgen, Andreas; Korten, Wolfram

    2016-02-01

    Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei and allows measuring electromagnetic moments that can be directly related to the nuclear shape. The availability of radioactive ion beams (RIBs) at energies near the Coulomb barrier has made it possible to study shape coexistence in a variety of short-lived exotic nuclei. This review presents a short overview of the methods related to multi-step Coulomb excitation experiments, followed by a discussion of several examples. The focus is on two mass regions where recent Coulomb excitation experiments have contributed to the quantitative understanding of shape coexistence: nuclei with mass A≈ 70 near the N = Z line and nuclei with A ≈ 100 near neutron number N = 60. Experimental results are summarized and their significance for understanding shape coexistence is discussed. Experimental observables such as quadrupole moments and electromagnetic transition strengths represent furthermore important benchmarks for advancing theoretical nuclear structure models. With several new RIB facilities planned and under construction, Coulomb excitation will remain to be an important tool to extend the studies of nuclear shapes toward more exotic systems, and to obtain a more comprehensive and quantitative understanding of shape coexistence.

  7. Effects of projectile resonances on the total, Coulomb, and nuclear breakup cross sections in the 6Li+152Sm reaction

    NASA Astrophysics Data System (ADS)

    Mukeru, B.; Lekala, M. L.

    2016-08-01

    In this paper we analyze the effects of the projectile resonances on the total, Coulomb, and nuclear breakup cross sections as well as on the Coulomb-nuclear interferences at different arbitrary incident energies. It is found that these resonances have non-negligible effects on the total, Coulomb, and nuclear breakup cross sections. Qualitatively, they have no effects on the constructiveness or destructiveness of the Coulomb-nuclear interferences. Quantitatively, we obtained that these resonances increase by 7.38%, 7.58%, and 20.30% the integrated total, Coulomb, and nuclear breakup cross sections, respectively at Elab=35 MeV . This shows that the nuclear breakup cross sections are more affected by the effects of the projectile resonances than their total and Coulomb breakup counterparts. We also obtain that the effects of the resonances on the total, Coulomb, and nuclear breakup cross sections decrease as the incident energy increases.

  8. Closed-form expression for the magnetic shielding constant of the relativistic hydrogenlike atom in an arbitrary discrete energy eigenstate: Application of the Sturmian expansion of the generalized Dirac-Coulomb Green function

    NASA Astrophysics Data System (ADS)

    Stefańska, Patrycja

    2016-07-01

    We present analytical derivation of the closed-form expression for the dipole magnetic shielding constant of a Dirac one-electron atom being in an arbitrary discrete energy eigenstate. The external magnetic field, by which the atomic state is perturbed, is assumed to be weak, uniform, and time independent. With respect to the atomic nucleus we assume that it is pointlike, spinless, motionless, and of charge Z e . Calculations are based on the Sturmian expansion of the generalized Dirac-Coulomb Green function [R. Szmytkowski, J. Phys. B 30, 825 (1997), 10.1088/0953-4075/30/4/007; erratum R. Szmytkowski, J. Phys. B 30, 2747(E) (1997), 10.1088/0953-4075/30/11/023], combined with the theory of hypergeometric functions. The final result is of an elementary form and agrees with corresponding formulas obtained earlier by other authors for some particular states of the atom.

  9. Extended optical model analyses of elastic scattering, direct reaction, and fusion cross sections for the {sup 9}Be+{sup 208}Pb system at near-Coulomb-barrier energies

    SciTech Connect

    So, W.Y.; Hong, S.W.; Kim, B.T.; Udagawa, T.

    2005-12-15

    Based on the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous {chi}{sup 2} analyses are performed for elastic scattering, DR, and fusion cross section data for the {sup 9}Be+{sup 208}Pb system at near-Coulomb-barrier energies. Similar {chi}{sup 2} analyses are also performed by taking into account only the elastic scattering and fusion data as was previously done by the present authors, and the results are compared with those of the full analysis including the DR cross section data as well. We find that the analyses using only elastic scattering and fusion data can produce very consistent and reliable predictions of cross sections, particularly when the DR cross section data are incomplete. Discussions are also given on the results obtained from similar analyses made earlier for the {sup 9}Be+{sup 209}Bi system.

  10. Coulomb dissociation of N,2120

    NASA Astrophysics Data System (ADS)

    Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamaño, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkäll, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Datta Pramanik, Ushasi; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Gonzalez Diaz, D.; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hâkan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Sanchez del Rio Saez, Jose; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai; R3B Collaboration

    2016-06-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N,2120 are reported. Relativistic N,2120 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the 19N (n ,γ )20N and 20N (n ,γ ) 21N excitation functions and thermonuclear reaction rates have been determined. The 19 (n ,γ )20N rate is up to a factor of 5 higher at T <1 GK with respect to previous theoretical calculations, leading to a 10% decrease in the predicted fluorine abundance.

  11. Three-body Coulomb systems using generalized angular-momentum S states

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Sims, J. S.

    1974-01-01

    An expansion of the three-body Coulomb potential in generalized angular-momentum eigenfunctions developed earlier by one of the authors is used to compute energy eigenvalues and eigenfunctions of bound S states of three-body Coulomb systems. The results for He, H(-), e(-)e(+)e(-), and pmu(-)p are compared with the results of other computational approaches.

  12. Nonstationary multistate Coulomb and multistate exponential models for nonadiabatic transitions

    SciTech Connect

    Ostrovsky, V. N.

    2003-07-01

    The nonstationary Schroedinger equation is considered in a finite basis of states. The model Hamiltonian matrix corresponds to a single diabatic potential curve with a Coulombic {approx}1/t time dependence. An arbitrary number of other diabatic potential curves are flat, i.e., time independent and have arbitrary energies. Related states are coupled by constant interactions with the Coulomb state. The resulting nonstationary Schroedinger equation is solved by the method of contour integral. Probabilities of transitions to any other state are obtained as t{yields}{infinity} in a simple analytical form for the case when the Coulomb state is populated initially (at instant of time t{yields}+0). The formulas apply both to the cases when a horizontal diabatic potential curve is crossed by the Coulomb one and to a noncrossing situation. In the limit of weak coupling, the transition probabilities are interpreted in terms of a sequence of pairwise Landau-Zener-type transitions. Mapping of the Coulomb model onto an exactly solvable exponential multistate model is established. For the special two-state case, the well-known Nikitin model is recovered.

  13. Coulomb explosion in aromatic molecules and their deuterated derivatives

    NASA Astrophysics Data System (ADS)

    Tzallas, P.; Kosmidis, C.; Graham, P.; Ledingham, K. W. D.; McCanny, T.; Hankin, S. M.; Singhal, R. P.; Taday, P. F.; Langley, A. J.

    2000-12-01

    Coulomb explosion within some aromatic molecules (furan, pyrrole, pyridine and pyrazine) and their deuterated derivatives induced by strong fs laser fields (˜ 4×10 16 W/cm2) is studied at λ=790 nm by means of time-of-flight (TOF) mass spectrometry. It is found that in hydrogenated molecules the Coulomb explosion process begins at internuclear distances about twice larger than the equilibrium distance ( Re), while the expansion of the molecular skeleton in the deuterated derivatives is smaller. Based on the estimated kinetic energy values of the fragment ions, the charge distribution in the transient molecular species is also discussed.

  14. Coulomb-damped resonant generators using piezoelectric transduction

    NASA Astrophysics Data System (ADS)

    Miller, L. M.; Mitcheson, P. D.; Halvorsen, E.; Wright, P. K.

    2012-06-01

    Switching interface circuits employed with piezoelectric energy harvesters can increase the electrical damping considerably over that achievable with passive rectifiers. We show that a piezoelectric harvester coupled to certain types of switching circuits becomes a Coulomb-damped resonant generator. This allows analysis of such harvester systems within a well-known framework and, subject to practical constraints, allows the optimal electrical damping to be achieved. In the piezoelectric pre-biasing technique, the Coulomb damping is set by a pre-bias voltage whose optimal value is derived as a function of piezoelectric harvester parameters.

  15. Convergence of Feynman integrals in Coulomb gauge QCD

    SciTech Connect

    Andraši, A.; Taylor, J.C.

    2014-12-15

    At 2-loop order, Feynman integrals in the Coulomb gauge are divergent over the internal energy variables. Nevertheless, it is known how to calculate the effective action, provided that the external gluon fields are all transverse. We show that, for the two-gluon Greens function as an example, the method can be extended to include longitudinal external fields. The longitudinal Greens functions appear in the BRST identities. As an intermediate step, we use a flow gauge, which interpolates between the Feynman and Coulomb gauges.

  16. Finiteness of the Coulomb gauge QCD perturbative effective action

    NASA Astrophysics Data System (ADS)

    Andraši, A.; Taylor, J. C.

    2015-05-01

    At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ-Lee term which was inserted into the Hamiltonian.

  17. On Coulomb collisions in bi-Maxwellian plasmas

    SciTech Connect

    Hellinger, Petr; Travnicek, Pavel M.

    2009-05-15

    Collisional momentum and energy transport in bi-Maxwellian plasmas with a drift velocity along the ambient magnetic field are calculated from both the Fokker-Planck and Boltzmann integral approximations. The transport coefficients obtained from the two approaches are identical to the leading order (proportional to the Coulomb logarithm) and are presented here in a closed form involving generalized double hypergeometric functions.

  18. Finiteness of the Coulomb gauge QCD perturbative effective action

    SciTech Connect

    Andraši, A.; Taylor, J.C.

    2015-05-15

    At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ–Lee term which was inserted into the Hamiltonian.

  19. Turbine blade cooling using Coulomb repulsion

    NASA Astrophysics Data System (ADS)

    Breidenthal, Robert; Colannino, Joseph; Dees, John; Goodson, David; Krichtafovitch, Igor; Prevo, Tracy

    2012-11-01

    Video photography and thermocouples reveal the effect of an electric field on the flow around a stationary, idealized turbine blade downstream of a combustor. The hot products of combustion naturally include positive ions. When the blade is an electrode and elevated to a positive potential, it tends to attract the free electrons and repel the positive ions. Due to their lower mass, the light electrons are rapidly swept toward the blade, while the positive ions are repelled. As they collide with the neutrals in the hot gas, the positive ions transfer their momentum so that a Coulomb body force is exerted on the hot gas. Cool, compressed air is injected out of the stationary blade near its leading edge to form a layer of film cooling. In contrast to the hot combustion products, the cool air is not ionized. At the interface between the hot gas and the cool air, the Coulomb repulsion force acts on the former but not the latter, analogous to gravity at a stratified interface. An effective Richardson number representing the ratio of potential to kinetic energy characterizes the topography of the interface. When the electric field is turned on, the repulsion of the hot gas from the idealized blade is evident in video recordings and thermocouple measurements.

  20. Elastic Coulomb breakup of 34Na

    NASA Astrophysics Data System (ADS)

    Singh, G.; Shubhchintak, Chatterjee, R.

    2016-08-01

    Background: 34Na is conjectured to play an important role in the production of seed nuclei in the alternate r -process paths involving light neutron rich nuclei very near the β -stability line, and as such, it is important to know its ground state properties and structure to calculate rates of the reactions it might be involved in, in the stellar plasma. Found in the region of `island of inversion', its ground state might not be in agreement with normal shell model predictions. Purpose: The aim of this paper is to study the elastic Coulomb breakup of 34Na on 208Pb to give us a core of 33Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of 34Na. Method: A fully quantum mechanical Coulomb breakup theory within the architecture of post-form finite range distorted wave Born approximation extended to include the effects of deformation is used to research the elastic Coulomb breakup of 34Na on 208Pb at 100 MeV/u. The triple differential cross section calculated for the breakup is integrated over the desired components to find the total cross-section, momentum, and angular distributions as well as the average momenta, along with the energy-angular distributions. Results: The total one neutron removal cross section is calculated to test the possible ground state configurations of 34Na. The average momentum results along with energy-angular calculations indicate 34Na to have a halo structure. The parallel momentum distributions with narrow full widths at half-maxima signify the same. Conclusion: We have attempted to analyze the possible ground state configurations of 34Na and in congruity with the patterns in the `island of inversion' conclude that even without deformation, 34Na should be a neutron halo with a predominant contribution to its ground state most probably coming from 33Na(3 /2+)⊗ 2 p3 /2ν configuration. We also surmise that it would certainly be useful and rewarding to test our

  1. PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems

    NASA Astrophysics Data System (ADS)

    Neilson, David; Senatore, Gaetano

    2009-05-01

    This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas

  2. Coulomb crystallization in classical and quantum systems

    NASA Astrophysics Data System (ADS)

    Bonitz, Michael

    2007-11-01

    Coulomb crystallization occurs in one-component plasmas when the average interaction energy exceeds the kinetic energy by about two orders of magnitude. A simple road to reach such strong coupling consists in using external confinement potentials the strength of which controls the density. This has been succsessfully realized with ions in traps and storage rings and also in dusty plasma. Recently a three-dimensional spherical confinement could be created [1] which allows to produce spherical dust crystals containing concentric shells. I will give an overview on our recent results for these ``Yukawa balls'' and compare them to experiments. The shell structure of these systems can be very well explained by using an isotropic statically screened pair interaction. Further, the thermodynamic properties of these systems, such as the radial density distribution are discussed based on an analytical theory [3]. I then will discuss Coulomb crystallization in trapped quantum systems, such as mesoscopic electron and electron hole plasmas in coupled layers [4,5]. These systems show a very rich correlation behavior, including liquid and solid like states and bound states (excitons, biexcitons) and their crystals. On the other hand, also collective quantum and spin effects are observed, including Bose-Einstein condensation and superfluidity of bound electron-hole pairs [4]. Finally, I consider Coulomb crystallization in two-component neutral plasmas in three dimensions. I discuss the necessary conditions for crystals of heavy charges to exist in the presence of a light component which typically is in the Fermi gas or liquid state. It can be shown that their exists a critical ratio of the masses of the species of the order of 80 [5] which is confirmed by Quantum Monte Carlo simulations [6]. Familiar examples are crystals of nuclei in the core of White dwarf stars, but the results also suggest the existence of other crystals, including proton or α-particle crystals in dense matter

  3. An entropic understanding of Coulomb force

    NASA Astrophysics Data System (ADS)

    Cho, Jin-Ho; Kim, Hyosung

    2012-02-01

    Exploiting Verlinde's proposal on the entropic understanding of Newton's law, we show that Coulomb force could also be understood as an entropically emergent force (rather than as a fundamental force). We apply Kaluza-Klein idea to Verlinde's formalism to obtain Coulomb interaction in the lower dimensions. The kinematics concerning the Kaluza-Klein momenta separates the interaction due to the momentum flow from the gravitational interaction. The momentum-charge conversion relation results in the precise form of Coulomb interaction.

  4. Supercurrent Drag via the Coulomb Interaction

    NASA Astrophysics Data System (ADS)

    Duan, Ji-Min; Yip, Sungkit

    1996-03-01

    We predict a supercurrent drag effect due to the Coulomb interaction between two parallel superconducting wires/layers. In contrast to previously explored frictional drag effect between two semiconducting quantum wells, our nondissipative drag mechanism ( J.-M. Duan and S. K. Yip, Phys. Rev. Lett.70), 3647 (1993). is based on considerations of the free energy of collective charge fluctuations. Our prediction has been confirmed experimentally ( X. Huang et al.), Phys. Rev. Lett.74, 4051 (1995). This mechanism generally exists in other nondissipative systems, such as double-layer quantum Hall syatems ( J.-M. Duan, Europhys. Lett.29), 489 (1995)., or between the two edge channels of a Hall bar, and between one-dimensional Luttinger Liquids.

  5. Investigation of Coulomb dipole polarization effects on reactions involving exotic nuclei

    NASA Astrophysics Data System (ADS)

    Fernández-García, J. P.; Alvarez, M. A. G.; Chamon, L. C.

    2015-07-01

    We have analyzed elastic scattering angular distributions and total reaction cross sections of the exotic nuclei 11,9Li on 208Pb, at energies below and above the Coulomb barrier. For this purpose, we have used an optical potential with no adjustable parameters, composed by the nuclear São Paulo potential, derived from the nonlocal nature of the interaction, and the Coulomb dipole polarization potential, derived from the semiclassical theory of Coulomb excitation. Within this formalism, we identified an unusual long-range absorption for the +208Pb 11Li system, which is dominated by the Coulomb interaction. We compare it to the absorption mechanisms observed for +208Pb6He which, unlike those of +208Pb11Li, take place at small interacting distances, where both Coulomb and nuclear interactions are important. The proposed approach shows to be a fundamental basis to study reactions involving exotic nuclei.

  6. Deep inelastic scattering near the Coulomb barrier

    SciTech Connect

    Gehring, J.; Back, B.; Chan, K.

    1995-08-01

    Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

  7. Coulombic contribution and fat center vortex model

    SciTech Connect

    Rafibakhsh, Shahnoosh; Deldar, Sedigheh

    2007-02-27

    The fat (thick) center vortex model is one of the phenomenological models which is fairly successful to interpret the linear potential between static sources. However, the Coulombic part of the potential has not been investigated by the model yet. In an attempt to get the Coulombic contribution and to remove the concavity of the potentials, we are studying different vortex profiles and vortex sizes.

  8. Stereoscopic Investigations of 3D Coulomb Balls

    SciTech Connect

    Kaeding, Sebastian; Melzer, Andre; Arp, Oliver; Block, Dietmar; Piel, Alexander

    2005-10-31

    In dusty plasmas particles are arranged due to the influence of external forces and the Coulomb interaction. Recently Arp et al. were able to generate 3D spherical dust clouds, so-called Coulomb balls. Here, we present measurements that reveal the full 3D particle trajectories from stereoscopic imaging.

  9. Coulomb blockade with neutral modes.

    PubMed

    Kamenev, Alex; Gefen, Yuval

    2015-04-17

    We study transport through a quantum dot in the fractional quantum Hall regime with filling factors ν=2/3 and ν=5/2, weakly coupled to the leads. We account for both injection of electrons to or from the leads, and quasiparticle rearrangement processes between the edge and the bulk of the quantum dot. The presence of neutral modes introduces topological constraints that modify qualitatively the features of the Coulomb blockade (CB). The periodicity of CB peak spacings doubles and the ratio of spacing between adjacent peaks approaches (in the low temperature and large dot limit) a universal value: 2∶1 for ν=2/3 and 3∶1 for ν=5/2. The corresponding CB diamonds alternate their width in the direction of the bias voltage and allow for the determination of the neutral mode velocity, and of the topological numbers associated with it. PMID:25933323

  10. Perturbed Coulomb potentials in the Klein-Gordon equation via the asymptotic iteration method

    SciTech Connect

    Barakat, T.

    2009-03-15

    The asymptotic iteration method is used to construct the exact energy eigenvalues for a Lorentz vector or a Lorentz scalar, and an equally mixed Lorentz vector and Lorentz scalar Coulombic potentials. Highly accurate and rapidly converging ground-state energies for Lorentz vector Coulomb with a Lorentz vector or a Lorentz scalar linear potential, V(r)=-{lambda}{sub 1}/r+krandV(r)=-{lambda}{sub 1}/randW(r)=kr, respectively, are obtained.

  11. The fusion fission and quasi-fission processes in the reaction 48Ca + 208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Prokhorova, E. V.; Bogachev, A. A.; Itkis, M. G.; Itkis, I. M.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Pashkevich, V. V.; Rusanov, A. Ya.

    2008-04-01

    Mass-energy distributions (MEDs) and capture-fission cross sections have been measured in the reaction 48Ca + 208Pb → 256No at the energies E=206-242 MeV using a double-arm time-of-flight spectrometer CORSET. It has been observed that MED of the fragments consists of two parts, namely, the classical fusion-fission process corresponding to the symmetric fission of 256No and quasi-fission "shoulders" corresponding to the light fragment masses ˜60-90 u and complimentary heavy fragment masses. The quasi-fission "shoulders" have a higher total kinetic energy (TKE) as compared with that expected for the classical fission. A mathematical formalism was employed for the MEDs fragment decomposition into fusion-fission and quasi-fission components. In the fusion-fission process a high-energy Super-Short mode has been discovered for the masses M=130-135 u and the TKE of ≈233 MeV.

  12. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

    ERIC Educational Resources Information Center

    Francisco, E.; And Others

    1988-01-01

    Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

  13. Search for narrow sum-energy lines in electron-positron pair emission from heavy-ion collisions near the Coulomb barrier

    SciTech Connect

    Ahmad, I.; Austin, S.M.; Back, B.B.; Betts, R.R.; Calaprice, F.P.; Chan, K.C.; Chishti, A.; Chowdhury, P.; Conner, C.; Dunford, R.W.; Fox, J.D.; Freedman, S.J.; Freer, M.; Gazes, S.B.; Hallin, A.L.; Happ, T.; Henderson, D.; Kaloskamis, N.I.; Kashy, E.; Kutschera, W.; Last, J.; Lister, C.J.; Liu, M.; Maier, M.R.; Mercer, D.J.; Mikolas, D.; Perera, P.A.A.; Rhein, M.D.; Roa, D.E.; Schiffer, J.P.; Trainor, T.A.; Wilt, P.; Winfield, J.S.; Wolanski, M.; Wolfs, F.L.H.; Wuosmaa, A.H.; Xu, G.; Young, A.; Yurkon, J.E. ||||||||||[Gesellsch

    1995-10-02

    The first results are presented from a new experiment, APEX, designed to study the previously reported sharp lines in sum-energy spectra of positrons and electrons produced in collisions of very heavy ions. Data were collected for {sup 238}U+{sup 181}Ta at 5.95, 6.10, and 6.30 MeV/u and {sup 238}U+{sup 232}Th at 5.95 MeV/u. In none of our analyses is any evidence found for sharp sum-energy lines. For the specific case of the isolated decay of a neutral particle of mass 1.4--2.1 MeV/{ital c}{sup 2}, the upper limits on cross sections obtained from the present data are significantly less than the previously reported cross sections.

  14. Study of Scattering 1H, 12C and 16O Nuclei on 1P-SHELL at Energy Near the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Amar, A.; Hamada, S.; Burtebayev, N.; Amangeldy, N.

    Differential cross sections for the 6,7Li(p,p)6,7Li and 10,11B(p,p)10,11B elastic scattering were measured over the proton laboratory energy range from 300 to 1050 keV. The transfer reaction of the elastic scattering of carbon and oxygen on oxygen and carbon nuclei was studied through different experiments with incident beam of energy 1.75 MeV/ nucleon. Depending on the measured data by us and literature data, we could enhance the potential parameters using ECIS88 Code, as well as SPI-GENOA Code. Good agreement between theoretical and experimental in whole range.

  15. Quantum solution for the one-dimensional Coulomb problem

    SciTech Connect

    Nunez-Yepez, H. N.; Salas-Brito, A. L.; Solis, Didier A.

    2011-06-15

    The one-dimensional hydrogen atom has been a much studied system with a wide range of applications. Since the pioneering work of Loudon [R. Loudon, Am. J. Phys. 27, 649 (1959).], a number of different features related to the nature of the eigenfunctions have been found. However, many of the claims made throughout the years in this regard are not correct--such as the existence of only odd eigenstates or of an infinite binding-energy ground state. We explicitly show that the one-dimensional hydrogen atom does not admit a ground state of infinite binding energy and that the one-dimensional Coulomb potential is not its own supersymmetric partner. Furthermore, we argue that at the root of many such false claims lies the omission of a superselection rule that effectively separates the right side from the left side of the singularity of the Coulomb potential.

  16. Coulomb chronometry to probe the decay mechanism of hot nuclei

    NASA Astrophysics Data System (ADS)

    Gruyer, D.; Frankland, J. D.; Bonnet, E.; Chbihi, A.; Ademard, G.; Boisjoli, M.; Borderie, B.; Bougault, R.; Galichet, E.; Gauthier, J.; Guinet, D.; Lautesse, P.; Le Neindre, N.; Legouée, E.; Lombardo, I.; Lopez, O.; Manduci, L.; Marini, P.; Mazurek, K.; Nadtochy, P. N.; Pârlog, M.; Rivet, M. F.; Roy, R.; Rosato, E.; Spadaccini, G.; Verde, G.; Vient, E.; Vigilante, M.; Wieleczko, J. P.; Indra Collaboration

    2015-12-01

    In 129Xe+natSn central collisions from 8 to 25 MeV/nucleon, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is determined. Strong Coulomb proximity effects are observed in the three-fragment final state. A comparison with Coulomb trajectory calculations shows that the time scale between the consecutive breakups decreases with increasing bombarding energy, becoming quasisimultaneous above excitation energy E*=4.0 ±0.5 MeV /nucleon . This transition from sequential to simultaneous breakup was interpreted as the signature of the onset of multifragmentation for the three-fragment exit channel in this system.

  17. Slow Noncollinear Coulomb Scattering in the Vicinity of the Dirac Point in Graphene.

    PubMed

    König-Otto, J C; Mittendorff, M; Winzer, T; Kadi, F; Malic, E; Knorr, A; Berger, C; de Heer, W A; Pashkin, A; Schneider, H; Helm, M; Winnerl, S

    2016-08-19

    The Coulomb scattering dynamics in graphene in energetic proximity to the Dirac point is investigated by polarization resolved pump-probe spectroscopy and microscopic theory. Collinear Coulomb scattering rapidly thermalizes the carrier distribution in k directions pointing radially away from the Dirac point. Our study reveals, however, that, in almost intrinsic graphene, full thermalization in all directions relying on noncollinear scattering is much slower. For low photon energies, carrier-optical-phonon processes are strongly suppressed and Coulomb mediated noncollinear scattering is remarkably slow, namely on a ps time scale. This effect is very promising for infrared and THz devices based on hot carrier effects. PMID:27588881

  18. Calculation of proton-deuteron breakup reactions including the Coulomb interaction between the two protons.

    PubMed

    Deltuva, A; Fonseca, A C; Sauer, P U

    2005-08-26

    The Coulomb interaction between the two protons is fully included in the calculation of proton-deuteron breakup with realistic interactions for the first time. The hadron dynamics is based on the purely nucleonic charge-dependent (CD) Bonn potential and its realistic extension CD Bonn +Delta to a coupled-channel two-baryon potential, allowing for single virtual Delta-isobar excitation. Calculations are done using integral equations in momentum space. The screening and renormalization approach is employed for including the Coulomb interaction. The Coulomb effect on breakup observables is seen at all energies in particular kinematic regimes. PMID:16197210

  19. Optical spectra and intensities of graphene magnetic dot bound to a negatively charged Coulomb impurity

    SciTech Connect

    Lee, C. M. E-mail: apkschan@cityu.edu.hk; Chan, K. S. E-mail: apkschan@cityu.edu.hk

    2014-07-28

    Employing numerical diagonalization, we study the optical properties of an electron in a monolayer-graphene magnetic dot bound to an off-center negatively charged Coulomb impurity based on the massless Dirac-Weyl model. Numerical results show that, since the electron-hole symmetry is broken by the Coulomb potential, the optical absorption spectra of the magnetic dot in the presence of a Coulomb impurity are different between the electron states and the hole states. Effects of both the magnetic field and the dot size on the absorption coefficient are presented as functions of the incident photon energies.

  20. Slow Noncollinear Coulomb Scattering in the Vicinity of the Dirac Point in Graphene

    NASA Astrophysics Data System (ADS)

    König-Otto, J. C.; Mittendorff, M.; Winzer, T.; Kadi, F.; Malic, E.; Knorr, A.; Berger, C.; de Heer, W. A.; Pashkin, A.; Schneider, H.; Helm, M.; Winnerl, S.

    2016-08-01

    The Coulomb scattering dynamics in graphene in energetic proximity to the Dirac point is investigated by polarization resolved pump-probe spectroscopy and microscopic theory. Collinear Coulomb scattering rapidly thermalizes the carrier distribution in k directions pointing radially away from the Dirac point. Our study reveals, however, that, in almost intrinsic graphene, full thermalization in all directions relying on noncollinear scattering is much slower. For low photon energies, carrier-optical-phonon processes are strongly suppressed and Coulomb mediated noncollinear scattering is remarkably slow, namely on a ps time scale. This effect is very promising for infrared and THz devices based on hot carrier effects.

  1. {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions at sub-coulomb energies

    SciTech Connect

    Tumino, A.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Sparta, R.; Aliotta, M.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Mrazek, J.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

    2012-11-20

    The {sup 2}H({sup 3}He,p{sup 3}H){sup 1}H and {sup 2}H({sup 3}He,n{sup 3}He){sup 1}H processes have been measured in quasi free kinematics to investigate for the first time the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions by means of the Trojan Horse Method. The {sup 3}He+d experiment was performed at 18 MeV, corresponding the a d-d energy range from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre Main Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the bare nucleus S(E) factors have been extracted for the first time. They deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

  2. Search for a systematic behavior of the breakup probability in reactions with weakly bound projectiles at energies around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Scheid, W.; Zhang, H. Q.

    2012-11-01

    Comparing the capture cross sections calculated without the breakup effect and experimental complete fusion cross sections, the breakup was analyzed in reactions with weakly bound projectiles 6,7,9Li, 9,11Be, and 6,8He. A trend of systematic behavior for the complete fusion suppression as a function of the target charge and bombarding energy is not achieved. The quasielastic backscattering is suggested as a useful tool to study the behavior of the breakup probability in reactions with weakly bound projectiles.

  3. Wigner solids, classical Coulomb lattices, and invariant average potential

    NASA Astrophysics Data System (ADS)

    Hall, G. L.; Rice, T. R.

    1980-04-01

    We show that Hall's analysis of K for Wigner solids, the Ihm and Cohen analysis of the Fuchs energy ɛ, some extensions of Hall's analysis, and some recent results for the classical Coulomb-lattice model provide a tight theoretical framework useful beyond the matter of Hall's conclusions about the ɛ for Wigner solids based on an incorrect relation accepted from the literature. We also comment on spherical approximations.

  4. Can Coulomb repulsion for charged particle beams be overcome?

    NASA Astrophysics Data System (ADS)

    Retsky, Michael W.

    2004-01-01

    Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into a small spots at large distances from the defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Since the nonreversible terms should be small, it might be possible to construct an electron beam directed energy weapon.

  5. Cation Recombination Energy/Coulomb Repulsion Effects in ETD/ECD as Revealed by Variation of Charge per Residue at Fixed Total Charge

    PubMed Central

    Mentinova, Marija; Crizer, David M.; Baba, Takashi; McGee, William M.; Glish, Gary L.; McLuckey, Scott A.

    2013-01-01

    Electron capture dissociation (ECD) and electron transfer dissociation (ETD) experiments in electrodynamic ion traps operated in the presence of a bath gas in the 1–10 mTorr range have been conducted on a common set of doubly protonated model peptides of the form X(AG)nX (X = lysine, arginine, or histidine, n=1, 2, or 4). The partitioning of reaction products was measured using thermal electrons, anions of azobenzene, and anions of 1,3-dinitrobenzene as reagents. Variation of n alters the charge per residue of the peptide cation, which affects recombination energy. The ECD experiments showed that H-atom loss is greatest for the n=1 peptides and decreases as n increases. Proton transfer in ETD, on the other hand, is expected to increase as charge per residue decreases (i.e., as n increases). These opposing tendencies were apparent in the data for the K(AG)nK peptides. H-atom loss appeared to be more prevalent in ECD than in ETD and is rationalized on the basis of either internal energy differences, differences in angular momentum transfer associated with the electron capture versus electron transfer processes, or a combination of the two. The histidine peptides showed the greatest extent of charge reduction without dissociation, the arginine peptides showed the greatest extent of side-chain cleavages, and the lysine peptides generally showed the greatest extent of partitioning into the c/z•-product ion channels. The fragmentation patterns for the complementary c- and z•-ions for ETD and ECD were found to be remarkably similar, particularly for the peptides with X = lysine. PMID:23568028

  6. Cation Recombination Energy/Coulomb Repulsion Effects in ETD/ECD as Revealed by Variation of Charge per Residue at Fixed Total Charge

    NASA Astrophysics Data System (ADS)

    Mentinova, Marija; Crizer, David M.; Baba, Takashi; McGee, William M.; Glish, Gary L.; McLuckey, Scott A.

    2013-11-01

    Electron capture dissociation (ECD) and electron transfer dissociation (ETD) experiments in electrodynamic ion traps operated in the presence of a bath gas in the 1-10 mTorr range have been conducted on a common set of doubly protonated model peptides of the form X(AG)nX (X = lysine, arginine, or histidine, n = 1, 2, or 4). The partitioning of reaction products was measured using thermal electrons, anions of azobenzene, and anions of 1,3-dinitrobenzene as reagents. Variation of n alters the charge per residue of the peptide cation, which affects recombination energy. The ECD experiments showed that H-atom loss is greatest for the n = 1 peptides and decreases as n increases. Proton transfer in ETD, on the other hand, is expected to increase as charge per residue decreases (i.e., as n increases). These opposing tendencies were apparent in the data for the K(AG)nK peptides. H-atom loss appeared to be more prevalent in ECD than in ETD and is rationalized on the basis of either internal energy differences, differences in angular momentum transfer associated with the electron capture versus electron transfer processes, or a combination of the two. The histidine peptides showed the greatest extent of charge reduction without dissociation, the arginine peptides showed the greatest extent of side-chain cleavages, and the lysine peptides generally showed the greatest extent of partitioning into the c/z•-product ion channels. The fragmentation patterns for the complementary c- and z•-ions for ETD and ECD were found to be remarkably similar, particularly for the peptides with X = lysine.

  7. Numerical approach to Coulomb gauge QCD

    SciTech Connect

    Matevosyan, Hrayr H.; Szczepaniak, Adam P.; Bowman, Patrick O.

    2008-07-01

    We calculate the ghost two-point function in Coulomb gauge QCD with a simple model vacuum gluon wave function using Monte Carlo integration. This approach extends the previous analytic studies of the ghost propagator with this ansatz, where a ladder-rainbow expansion was unavoidable for calculating the path integral over gluon field configurations. The new approach allows us to study the possible critical behavior of the coupling constant, as well as the Coulomb potential derived from the ghost dressing function. We demonstrate that IR enhancement of the ghost correlator or Coulomb form factor fails to quantitatively reproduce confinement using Gaussian vacuum wave functional.

  8. On-site screened Coulomb interactions for localized electrons in transition metal oxides and defect systems

    NASA Astrophysics Data System (ADS)

    Shih, Bi-Ching; Zhang, Peihong; Department of Physics Team

    2011-03-01

    Electronic and structural properties of strongly correlated material systems are largely determined by the strength of the on-site Coulomb interaction. Theoretical models devised to capture the physics of strongly correlated materials usually involve screened Coulomb interactions as adjustable parameters. We present first-principles results for the screened on-site Coulomb and exchange energy for transition metal oxides. The dielectric screening is calculated within the random phase approximation and the localized electrons are represented by maximally localized Wannier functions. We further extend our study to calculate on-site Coulomb interactions for localized defect states in semiconductors. We acknowledge the computational support provided by the Center for Computational Research at the University at Buffalo, SUNY. This work is supported by the National Science Foundation under Grant No. DMR-0946404 and by the Department of Energy under Grant No. DE-SC0002623.

  9. Crystallization in two-component Coulomb systems.

    PubMed

    Bonitz, M; Filinov, V S; Fortov, V E; Levashov, P R; Fehske, H

    2005-12-01

    The analysis of Coulomb crystallization is extended from one-component to two-component plasmas. Critical parameters for the existence of Coulomb crystals are derived for both classical and quantum crystals. In the latter case, a critical mass ratio of the two charged components is found, which is of the order of 80. Thus, holes in semiconductors with sufficiently flat valence bands are predicted to spontaneously order into a regular lattice. Such hole crystals are intimately related to ion Coulomb crystals in white dwarf and neutron stars as well as to ion crystals produced in the laboratory. A unified phase diagram of two-component Coulomb crystals is presented and is verified by first-principles computer simulations. PMID:16384315

  10. Conductance through a proximitized nanowire in the Coulomb blockade regime

    NASA Astrophysics Data System (ADS)

    van Heck, Bernard; Lutchyn, Roman; Glazman, Leonid

    Motivated by recent experiments of the Copenhagen group on InAs nanowires with epitaxial Al, we investigate the two-terminal conductance of a strongly proximitized nanowire in the Coulomb blockade regime. We identify the leading electron transport processes at zero applied magnetic field B as well as at finite fields, suppressing the induced gap Δind (B) . In the conventional superconducting phase, the conductance is controlled by the sequential Cooper pair tunneling if Δind (B) exceeds the charging energy Ec, and by the elastic single-electron processes if Δind (B) Coulomb blockade peaks, which explains the experimental finding in Ref.. We also develop a quantitative theory for the differential conductance and examine its evolution across the topological transition point.

  11. Coulomb attraction in optical spectra of quantum discs

    NASA Astrophysics Data System (ADS)

    Adolph, B.; Glutsch, S.; Bechstedt, F.

    1994-06-01

    We present a theory which describes the influence of the Coulomb interaction on the optical spectra of quantum discs within the envelope function formalism. Starting from a non-local Elliott formula luminescence is traced back to two-particle wave functions and energies. They are solutions of the corresponding Schrödinger equation for an electron-hole pair under the influence of the Coulomb attraction and confinement potentials determined by the spatial variation of the band edges of the considered microstructure. We present a complete numerical solution of the two-particle problem for flat quantum dots, i.e. discs for which the size quantization in growth direction is much stronger than that in the xy-plane. We discuss two different situations, single discs with infinite and finite confinement potentials. Resulting theoretical lineshapes are compared with luminescence spectra obtained recently for quantum discs fabricated by laser-induced thermal cation interdiffusion in quantum-well structures.

  12. Interplay of Coulomb interaction and spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Bünemann, Jörg; Linneweber, Thorben; Löw, Ute; Anders, Frithjof B.; Gebhard, Florian

    2016-07-01

    We employ the Gutzwiller variational approach to investigate the interplay of Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model. Already in the paramagnetic phase we find a substantial renormalization of the spin-orbit coupling that enters the effective single-particle Hamiltonian for the quasiparticles. Only close to half band-filling and for sizable Coulomb interaction do we observe clear signatures of Hund's atomic rules for spin, orbital, and total angular momentum. For a finite local Hund's rule exchange interaction we find a ferromagnetically ordered state. The spin-orbit coupling considerably reduces the size of the ordered moment, it generates a small ordered orbital moment, and it induces a magnetic anisotropy. To investigate the magnetic anisotropy energy, we use an external magnetic field that tilts the magnetic moment away from the easy axis (1 ,1 ,1 ) .

  13. Coulomb excitation of C{sub 60} molecules

    SciTech Connect

    Esbensen, H.; Berry, H.G.; Cheng, S.

    1995-08-01

    The ionization and dissociation of C{sub 60} molecules in the Coulomb field from fast, highly-charged xenon ions was measured recently at ATLAS. The Coulomb excitation was modeled as a coherent excitation of the giant plasmon resonance. Guided by photo-absorption measurements, single-plasmon excitations were identified with the production of single-charged C{sub 60}{sup +} molecular ions. The calculated cross sections do indeed reproduce the beam energy-dependence of the measured C{sub 60}{sup +} yield. The calculations show that single-plasmon excitations are responsible for about half of the total reaction cross section. The other half, i.e., multiplasmon excitations, leads to multiple ionization and dissociation of the molecule.

  14. Cooling of cryogenic electron bilayers via the Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Gamble, John King; Friesen, Mark; Joynt, Robert; Coppersmith, S. N.

    2011-09-01

    Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure and analyze the power transfer. We show that, across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.

  15. Elastic scattering of Beryllium isotopes near the Coulomb barrier

    SciTech Connect

    Di Pietro, A.; Figuera, P.; Amorini, F.; Fisichella, M.; Lattuada, M.; Musumarra, A.; Pellegriti, M. G.; Randisi, G.; Rizzo, F.; Santonocito, D.; Scalia, G.; Scuderi, V.; Strano, E.; Torresi, D.; Papa, M.; Acosta, L.; Martel, I.; Perez-Bernal, F.; Borge, M. J. G.; Tengblad, O.

    2011-10-28

    In this contribution, results of experiments performed with the three Beryllium isotopes {sup 9,10,11}Be on a medium mass {sup 64}Zn target, at a center of mass energy of {approx_equal}1.4 the Coulomb barrier, will be discussed. Elastic scattering angular distributions have been measured for the {sup 9,10}Be reactions. In the {sup 11}Be case the quasielastic scattering angular distribution was obtained. In the halo nucleus case, the angular distribution exhibit a non-Fresnel-type pattern with a strong damping of the Coulomb-nuclear interference peak. Moreover, it is found that the total reaction cross-section for the halo nucleus induced collision is more than double the ones extracted in the collisions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the {sup 11}Be case could be attributed to transfer and/or break-up events.

  16. On the modelling of Coulomb friction

    NASA Astrophysics Data System (ADS)

    Cull, S. J.; Tucker, R. W.

    1999-03-01

    This paper analyses two different representations of Coulomb friction in the context of a dynamic simulation of the torsional vibrations of a driven drill-string. A simple model is used to compare the relative merits of a piecewise analytic approach using a discontinuous friction profile to a numerical integration using a smooth nonlinear representation of the Coulomb friction. In both cases the effects of viscous damping on the excitation of torsional relaxation oscillations are exhibited.

  17. Modelling Coulomb Collisions in Anisotropic Plasmas

    NASA Astrophysics Data System (ADS)

    Hellinger, P.; Travnicek, P. M.

    2009-12-01

    Collisional transport in anisotropic plasmas is investigated comparing the theoretical transport coefficients (Hellinger and Travnicek, 2009) for anisotropic particles with the results of the corresponding Langevin equation, obtained as a generalization of Manheimer et al. (1997). References: Hellinger, P., and P. M. Travnicek (2009), On Coulomb collisions in bi-Maxwellian plasmas, Phys. Plasmas, 16, 054501. Manheimer, W. M., M. Lampe and G. Joyce (1997), Langevin representation of Coulomb collisions in PIC simulations, J. Comput. Phys., 138, 563-584.

  18. Off-shell Jost solutions for Coulomb and Coulomb-like interactions in all partial waves

    SciTech Connect

    Laha, U.; Bhoi, J.

    2013-01-15

    By exploiting the theory of ordinary differential equations, with judicious use of boundary conditions, interacting Green's functions and their integral transforms together with certain properties of higher transcendental functions, useful analytical expressions for the off-shell Jost solutions for motion in Coulomb and Coulomb-nuclear potentials are derived in maximal reduced form through different approaches to the problem in the representation space. The exact analytical expressions for the off-shell Jost solutions for Coulomb and Coulomb-like potentials are believed to be useful for the description of the charged particle scattering/reaction processes.

  19. Electron attraction mediated by Coulomb repulsion

    NASA Astrophysics Data System (ADS)

    Hamo, A.; Benyamini, A.; Shapir, I.; Khivrich, I.; Waissman, J.; Kaasbjerg, K.; Oreg, Y.; von Oppen, F.; Ilani, S.

    2016-07-01

    One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed ‘excitonic’, promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the ‘glue’ that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.

  20. Electron attraction mediated by Coulomb repulsion.

    PubMed

    Hamo, A; Benyamini, A; Shapir, I; Khivrich, I; Waissman, J; Kaasbjerg, K; Oreg, Y; von Oppen, F; Ilani, S

    2016-07-21

    One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed 'excitonic', promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the 'glue' that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter. PMID:27443742

  1. Study of ultrasonic attenuation in f-electron systems in the paramagnetic limit of Coulomb interaction

    SciTech Connect

    Shadangi, Asit Ku.; Rout, G. C.

    2015-05-15

    We report here a microscopic model study of ultrasonic attenuation in f-electron systems based on Periodic Anderson Model in which Coulomb interaction is considered within a mean-field approximation for a weak interaction. The Phonon is coupled to the conduction band and f-electrons. The phonon Green's function is calculated by Zubarev's technique of the Green's function method. The temperature dependent ultrasonic attenuation co-efficient is calculated from the imaginary part of the phonon self-energy in the dynamic and long wave length limit. The f-electron occupation number is calculated self-consistently in paramagnetic limit of Coulomb interaction. The effect of the Coulomb interaction on ultrasonic attenuation is studied by varying the phonon coupling parameters to the conduction and f-electrons, hybridization strength, the position of f-level and the Coulomb interaction Strength. Results are discussed on the basis of experimental results.

  2. Collective modes in charge-density waves and long-range Coulomb interactions

    NASA Astrophysics Data System (ADS)

    Virosztek, Attila; Maki, Kazumi

    1993-07-01

    We study theoretically the collective modes in charge-density waves in the presence of long-range Coulomb interaction. We find that earlier works by Takada and his collaborators are inadequate since they introduced inconsistent approximations in evaluating a variety of correlation functions. The amplitude mode is unaffected by the Coulomb interaction, while the phase mode splits into the phason with linear dispersion (i.e., acoustic mode) and the optical mode with an energy gap in the presence of the Coulomb interaction. In particular, we establish the temperature dependence of the phason velocity vφ. A comparison with recent neutron-scattering data on the phason velocity in the charge-density wave of a single crystal of blue bronze K0.3MoO3 indicates that mean-field theory which includes the long-range Coulomb interaction gives an excellent description of the observed phason velocity.

  3. Isospin effects via Coulomb forces on the onset of multifragmentation in light and heavily charged systems

    NASA Astrophysics Data System (ADS)

    Sharma, Arun; Bharti, Arun

    2016-03-01

    We concurrently study the isospin effects via Coulomb forces and the nuclear equation of state and its momentum dependence on the onset of multifragmentation, i.e., critical energy point, in the light and heavily charged reactions of 40Ar + 45Sc and 84Kr + 197Au , respectively, using the isospin-dependent quantum molecular dynamics model. We find that Coulomb forces influence the onset of multifragmentation and result in the shift of the critical energy point towards lower and higher incident energies with and without their presence, respectively. Also, we observe that the critical energy point is sharper for the heavily charged system of 84Kr + 197Au when compared with the light charged system of 40Ar + 45Sc , where a small dip is observed and thus leads to the dependence of onset of multifragmentation, i.e., the critical energy point, on the reaction asymmetry as well as on the Coulomb forces.

  4. Effect of Coulomb collision on the negative ion extraction mechanism in negative ion sources.

    PubMed

    Goto, I; Miyamoto, K; Nishioka, S; Mattei, S; Lettry, J; Abe, S; Hatayama, A

    2016-02-01

    To improve the H(-) ion beam optics, it is necessary to understand the energy relaxation process of surface produced H(-) ions in the extraction region of Cs seeded H(-) ion sources. Coulomb collisions of charged particles have been introduced to the 2D3V-PIC (two dimension in real space and three dimension in velocity space particle-in-cell) model for the H(-) extraction by using the binary collision model. Due to Coulomb collision, the lower energy part of the ion energy distribution function of H(-) ions has been greatly increased. The mean kinetic energy of the surface produced H(-) ions has been reduced to 0.65 eV from 1.5 eV. It has been suggested that the beam optics of the extracted H(-) ion beam is strongly affected by the energy relaxation process due to Coulomb collision. PMID:26932090

  5. Effect of Coulomb collision on the negative ion extraction mechanism in negative ion sources

    NASA Astrophysics Data System (ADS)

    Goto, I.; Miyamoto, K.; Nishioka, S.; Mattei, S.; Lettry, J.; Abe, S.; Hatayama, A.

    2016-02-01

    To improve the H- ion beam optics, it is necessary to understand the energy relaxation process of surface produced H- ions in the extraction region of Cs seeded H- ion sources. Coulomb collisions of charged particles have been introduced to the 2D3V-PIC (two dimension in real space and three dimension in velocity space particle-in-cell) model for the H- extraction by using the binary collision model. Due to Coulomb collision, the lower energy part of the ion energy distribution function of H- ions has been greatly increased. The mean kinetic energy of the surface produced H- ions has been reduced to 0.65 eV from 1.5 eV. It has been suggested that the beam optics of the extracted H- ion beam is strongly affected by the energy relaxation process due to Coulomb collision.

  6. Implosive Interatomic Coulombic decay in the simplest molecular anion

    NASA Astrophysics Data System (ADS)

    Greene, Chris H.; Perez-Rios, Jesus; Slipchenko, Lyudmila

    2016-05-01

    Interatomic Coulombic decay (ICD) has been extensively studied in different systems: from diatomic systems such as He2 up to more complex chemical systems with interest in biochemistry. Independently of the size and complexity of the system, the ICD process proposed involves the emission of an electron through exchange of a virtual photon. The present theoretical study investigates the ICD process in the helium hydride anion, which involves two final product states that can be produced through a Coulomb implosion following high energy ejection of a He 1s electron accompanied by excitation to He+(n = 2) . One of the subsequent decay channels is associated with the usual emission of a single electron, to produce a stable molecule: HeH+, which can compete with the usual dissociated final state of the system. The second channel involves the emission of two electrons, leading to the usual Coulomb explosion of the final product ions He+(1 s) + H + . In addition, the process of formation of the helium hydride anion is analyzed in terms of the existing technology of ionic molecular beams and buffer gas cooling techniques. This work is supported by the National Science Foundation under Grant PHY-1306905.

  7. Quasi-exactly solvable relativistic soft-core Coulomb models

    SciTech Connect

    Agboola, Davids Zhang, Yao-Zhong

    2012-09-15

    By considering a unified treatment, we present quasi exact polynomial solutions to both the Klein-Gordon and Dirac equations with the family of soft-core Coulomb potentials V{sub q}(r)=-Z/(r{sup q}+{beta}{sup q}){sup 1/q}, Z>0, {beta}>0, q{>=}1. We consider cases q=1 and q=2 and show that both cases are reducible to the same basic ordinary differential equation. A systematic and closed form solution to the basic equation is obtained using the Bethe ansatz method. For each case, the expressions for the energies and the allowed parameters are obtained analytically and the wavefunctions are derived in terms of the roots of a set of Bethe ansatz equations. - Highlights: Black-Right-Pointing-Pointer The relativistic bound-state solutions of the soft-core Coulomb models. Black-Right-Pointing-Pointer Quasi-exact treatments of the Dirac and Klein-Gordon equations for the soft-core Coulomb models. Black-Right-Pointing-Pointer Solutions obtained in terms of the roots to the Bethe ansatz equations. Black-Right-Pointing-Pointer The hidden Lie algebraic structure discussed for the models. Black-Right-Pointing-Pointer Results useful in describing mesonic atoms and interaction of intense laser fields with atom.

  8. Strong Coulomb effects on pions produced in heavy ion collisons

    NASA Astrophysics Data System (ADS)

    Sullivan, J. P.; Bistirlich, J. A.; Bowman, H. R.; Bossingham, R.; Buttke, T.; Crowe, K. M.; Frankel, K. A.; Martoff, C. J.; Miller, J.; Murphy, D. L.; Rasmussen, J. O.; Zajc, W. A.; Hashimoto, O.; Koike, M.; Péter, J.; Benenson, W.; Crawley, G. M.; Kashy, E.; Nolen, J. A.

    1982-03-01

    Doubly differential cross sections for the production of π+ and π- near the velocity of the incident beam for pion laboratory angles from 0 to 20 degrees are presented. Beams of 20Ne with EA=280, 380, and 480 MeV and 40Ar with EA=535 MeV incident on C, NaF, KCl, Cu, and U targets were used. A sharp peak in the π- spectrum and a depression in the π+ spectrum is observed at 0° near the incident projectile velocity. The effect is explained in terms of Coulomb interactions between pions and fragments of the incident beam. Least squares fits to the data using the Coulomb correction formulas of Gyulassy and Kauffmann and an effective projectile fragment charge are made. The relationship between these data and previously measured projectile fragmentation data is discussed and a simple parametrization of projectile mass, target mass, and beam energy dependence of the differential cross sections is given. NUCLEAR REACTIONS C, NaF, Cu, U (20Ne,π+/-)X, EA=280-480 MeV; C, KCl (40Ar,π+/-)X, EA=535 MeV; measured σ(Eπ,θπ), θπ=0°-20°, π velocity near beam velocity; deduced projectile fragment charges, Coulomb effects.

  9. Proton radiography, nuclear cross sections and multiple Coulomb scattering

    SciTech Connect

    Sjue, Sky K.

    2015-11-04

    The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.

  10. Coulomb excitations for a short linear chain of metallic shells

    SciTech Connect

    Zhemchuzhna, Liubov; Gumbs, Godfrey; Iurov, Andrii; Huang, Danhong; Gao, Bo

    2015-03-15

    A self-consistent-field theory is given for the electronic collective modes of a chain containing a finite number, N, of Coulomb-coupled spherical two-dimensional electron gases arranged with their centers along a straight line, for simulating electromagnetic response of a narrow-ribbon of metallic shells. The separation between nearest-neighbor shells is arbitrary and because of the quantization of the electron energy levels due to their confinement to the spherical surface, all angular momenta L of the Coulomb excitations, as well as their projections M on the quantization axis, are coupled. However, for incoming light with a given polarization, only one angular momentum quantum number is usually required. Therefore, the electromagnetic response of the narrow-ribbon of metallic shells is expected to be controlled externally by selecting different polarizations for incident light. We show that, when N = 3, the next-nearest-neighbor Coulomb coupling is larger than its value if they are located at opposite ends of a right-angle triangle forming the triad. Additionally, the frequencies of the plasma excitations are found to depend on the orientation of the line joining them with respect to the axis of quantization since the magnetic field generated from the induced oscillating electric dipole moment on one sphere can couple to the induced magnetic dipole moment on another. Although the transverse inter-shell electromagnetic coupling can be modeled by an effective dynamic medium, the longitudinal inter-shell Coulomb coupling, on the other hand, can still significantly modify the electromagnetic property of this effective medium between shells.

  11. Coulomb interaction effects on the Majorana states in quantum wires.

    PubMed

    Manolescu, A; Marinescu, D C; Stanescu, T D

    2014-04-30

    The stability of the Majorana modes in the presence of a repulsive interaction is studied in the standard semiconductor wire-metallic superconductor configuration. The effects of short-range Coulomb interaction, which is incorporated using a purely repulsive δ-function to model the strong screening effect due to the presence of the superconductor, are determined within a Hartree-Fock approximation of the effective Bogoliubov-De Gennes Hamiltonian that describes the low-energy physics of the wire. Through a numerical diagonalization procedure we obtain interaction corrections to the single particle eigenstates and calculate the extended topological phase diagram in terms of the chemical potential and the Zeeman energy. We find that, for a fixed Zeeman energy, the interaction shifts the phase boundaries to a higher chemical potential, whereas for a fixed chemical potential this shift can occur either at lower or higher Zeeman energies. These effects can be interpreted as a renormalization of the g-factor due to the interaction. The minimum Zeeman energy needed to realize Majorana fermions decreases with the increasing strength of the Coulomb repulsion. Furthermore, we find that in wires with multi-band occupancy this effect can be enhanced by increasing the chemical potential, i.e. by occupying higher energy bands. PMID:24722427

  12. Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals

    NASA Astrophysics Data System (ADS)

    Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

    2007-04-01

    The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine α-helix chains and three-dimensional diamond pieces.

  13. Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals.

    PubMed

    Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

    2007-04-14

    The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine alpha-helix chains and three-dimensional diamond pieces. PMID:17444700

  14. Initial results of a full kinetic simulation of RF H{sup −} source including Coulomb collision process

    SciTech Connect

    Mochizuki, S.; Shibata, T.; Nishida, K.; Hatayama, A.; Mattei, S.; Lettry, J.

    2015-04-08

    In order to evaluate Electron Energy Distribution Function (EEDF) more correctly for radio frequency inductively coupled plasma (RF-ICP) in hydrogen negative ion sources, the Electromagnetic Particle-In-Cell (EM-PIC) simulation code has been improved by taking into account electron-electron Coulomb collision. Binary collision model is employed to model Coulomb collision process and we have successfully modeled it. The preliminary calculation including Coulomb collision has been done and it is shown that Coulomb collision doesn’t have significant effects under the condition: electron density n{sub e} ∼ 10{sup 18} m{sup −3} and high gas pressure p{sub H{sub 2}} = 3 Pa, while it is necessary to include Coulomb collision under high electron density and low gas pressure conditions.

  15. 1/f Noise in a Coulomb Glass.

    NASA Astrophysics Data System (ADS)

    Yu, Clare C.; Shtengel, Kirill

    2002-03-01

    Low frequency 1/f noise is found in Coulomb glasses, among other systems with slow relaxation. It has been recently studied in detail in Si:B in the experimental work of Massey and Lee [1]. They concluded that their findings were inconsistent with the single-particle mechanisms proposed earlier. We show that the observed noise can be produced by charge fluctuations due to electrons hopping between isolated sites and a percolating network at low temperatures [2]. Coulomb interactions are included through the Coulomb gap in the density of states. The low frequency noise spectrum goes as ω^-α with α slightly larger than 1. This result, together with the temperature dependence of α and the noise amplitude are in good agreement with the experiments of Massey and Lee. [1] J. G. Massey and Mark Lee, Phys. Rev. Lett. 79, 3986 (1997). [2] Kirill Shtengel and Clare C. Yu (2001), cond-mat/0111302.

  16. Coulomb force as an entropic force

    SciTech Connect

    Wang Tower

    2010-05-15

    Motivated by Verlinde's theory of entropic gravity, we give a tentative explanation to the Coulomb's law with an entropic force. When trying to do this, we find the equipartition rule should be extended to charges and the concept of temperature should be reinterpreted. If one accepts the holographic principle as well as our generalizations and reinterpretations, then Coulomb's law, the Poisson equation, and the Maxwell equations can be derived smoothly. Our attempt can be regarded as a new way to unify the electromagnetic force with gravity, from the entropic origin. Possibly some of our postulates are related to the D-brane picture of black hole thermodynamics.

  17. Nonlocal formulation of spin Coulomb drag

    NASA Astrophysics Data System (ADS)

    D'Amico, I.; Ullrich, C. A.

    2013-10-01

    The spin Coulomb drag (SCD) effect occurs in materials and devices where charged carriers with different spins exchange momentum via Coulomb scattering. This causes frictional forces between spin-dependent currents that lead to intrinsic dissipation, which may limit spintronics applications. A nonlocal formulation of SCD is developed which is valid for strongly inhomogeneous systems such as nanoscale spintronics devices. This nonlocal formulation of SCD is successfully applied to linewidths of intersubband spin plasmons in semiconductor quantum wells, where experiments have shown that the local approximation fails.

  18. Coulomb balls in Experiment and Simulation

    SciTech Connect

    Block, D.; Arp, O.; Piel, A.; Melzer, A.

    2005-10-31

    Recently, it was shown that it is possible to confine spherical dust clouds in a plasma. It was found that these dust clouds have a crystalline structure which differs notably from the well known fcc, bcc and hcp order in extended crystalline systems. The experiments show that the particles arrange in nested shells with hexagonal order on individual shells. The high transparency and the rather slow time scales of Coulomb balls allow to observe individual particles with video microscopy techniques and therefore to determine the structural properties of Coulomb balls with high accuracy. This contribution presents a comparison of experimental results and MD-Simulations.

  19. Observation of ionic Coulomb blockade in nanopores

    NASA Astrophysics Data System (ADS)

    Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; di Ventra, Massimiliano; Radenovic, Aleksandra

    2016-08-01

    Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels.

  20. Coulomb string tension, asymptotic string tension, and the gluon chain

    SciTech Connect

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  1. The Coulomb excitations of Bernal bilayer graphene under external fields

    SciTech Connect

    Wu, Jhao-Ying; Lin, Ming-Fa

    2014-03-31

    We study the field effects on the Coulomb excitation spectrum of Bernal bilayer graphene by using the tight-binding model and the random-phase approximation. The electric field opens the band gap and creates the saddle points, the latter brings about a prominent interband plasmon. On the other hand, the magnetic field induces the dispersionless Landau levels (LLs) that causes the inter-LL plasmons. The two kinds of field-induced plasmon modes can be further tuned by the magnitude of momentum transfer and the field strength. The predicted results may be further validated by the inelastic light-scattering or high-resolution electron-energy-loss spectroscopy (HREELLS)

  2. Challenges in calculating molecular systems with Coulomb interactions

    NASA Astrophysics Data System (ADS)

    Kirnosov, Nikita; Sharkey, Keeper; Adamowicz, Ludwik

    2014-03-01

    The highly accurate quantum mechanical calculations are not only crucial for high-resolution experimental data verification, but may also serve as a guide in the field of exotic systems exploration. Including all non-relativistic effects in a single-step variational approach and rigorously separating out the center of mass motion allows us to build a reliable model for calculating bound states of molecular systems with Coulomb interactions. In these calculations the wave function of the system is expanded in terms of explicitly correlated Gaussian (ECG) basis functions. Examples of calculations of energies and other properties of some molecular systems will be presented.

  3. Topological defect motifs in two-dimensional Coulomb clusters.

    PubMed

    Radzvilavičius, A; Anisimovas, E

    2011-09-28

    We study the distribution of topological defects in two-dimensional Coulomb clusters with parabolic lateral confinement. The minima hopping algorithm based on molecular dynamics is used to efficiently locate the ground- and low-energy metastable states, and their structure is analysed by means of the Delaunay triangulation. The size, structure and distribution of geometry-induced lattice imperfections strongly depends on the system size and the energetic state. Besides isolated disclinations and dislocations, classification of defect motifs includes defect compounds-grain boundaries, rosette defects, vacancies and interstitial particles. Proliferation of defects in metastable configurations destroys the orientational order of the Wigner lattice. PMID:21891854

  4. The distinguishable cluster approach from a screened Coulomb formalism.

    PubMed

    Kats, Daniel

    2016-01-28

    The distinguishable cluster doubles equations have been derived starting from an effective screened Coulomb formalism and a particle-hole symmetric formulation of the Fock matrix. A perturbative triples correction to the distinguishable cluster with singles and doubles (DCSD) has been introduced employing the screened integrals. It is shown that the resulting DCSD(T) method is more accurate than DCSD for reaction energies and is less sensitive to the static correlation than coupled cluster with singles and doubles with a perturbative triples correction. PMID:26827197

  5. Molecular Dynamics Simulations of Coulomb Explosion

    SciTech Connect

    Bringa, E M

    2002-05-17

    A swift ion creates a track of electronic excitations in the target material. A net repulsion inside the track can cause a ''Coulomb Explosion'', which can lead to damage and sputtering of the material. Here we report results from molecular-dynamics (MD) simulations of Coulomb explosion for a cylindrical track as a function of charge density and neutralization/quenching time, {tau}. Screening by the free electrons is accounted for using a screened Coulomb potential for the interaction among charges. The yield exhibits a prompt component from the track core and a component, which dominates at higher excitation density, from the heated region produced. For the cases studied, the number of atoms ejected per incident ion, i.e. the sputtering yield Y, is quadratic with charge density along the track as suggested by simple models. Y({tau} = 0.2 Debye periods) is nearly 20% of the yield when there is no neutralization ({tau} {yields} {infinity}). The connections between ''Coulomb explosions'', thermal spikes and measurements of electronic sputtering are discussed.

  6. BRST invariance in Coulomb gauge QCD

    NASA Astrophysics Data System (ADS)

    Andraši, A.; Taylor, J. C.

    2015-12-01

    In the Coulomb gauge, the Hamiltonian of QCD contains terms of order ħ2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how do these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g4) , example.

  7. Coulombic Effects in Ion Mobility Spectrometry

    PubMed Central

    Tolmachev, Aleksey V.; Clowers, Brian H.; Belov, Mikhail E.; Smith, Richard D.

    2009-01-01

    Ion mobility spectrometry (IMS) has been increasingly employed in a number of applications. When coupled to mass spectrometry (MS), IMS becomes a powerful analytical tool for separating complex samples and investigating molecular structure. Therefore, improvements in IMS-MS instrumentation, e.g. IMS resolving power and sensitivity, are highly desirable. Implementation of an ion trap for accumulation and pulsed ion injection to IMS based on the ion funnel has provided considerably increased ion currents, and thus a basis for improved sensitivity and measurement throughput. However, large ion populations may manifest Coulombic effects contributing to the spatial dispersion of ions traveling in the IMS drift tube, and reduction in the IMS resolving power. In this study, we present an analysis of Coulombic effects on IMS resolution. Basic relationships have been obtained for the spatial evolution of ion packets due to Coulombic repulsion. The analytical relationships were compared with results of a computer model that simulates IMS operation based on a first principles approach. Initial experimental results reported here are consistent with the computer modeling. A noticeable decrease in the IMS resolving power was observed for ion populations of >10,000 elementary charges. The optimum IMS operation conditions which would minimize the Coulombic effects are discussed. PMID:19438247

  8. The Pioneer Anomaly as a Coulomb Attraction

    NASA Astrophysics Data System (ADS)

    Morris, Steven

    2016-06-01

    The anomalous acceleration of the Pioneer 10 and Pioneer 11 spacecraft can be explained as a Coulomb attraction between the positively-charged Solar System (due to cosmic rays) and the negatively-charged spacecraft (due to alpha-particle emission from the radioisotope thermoelectric generators).

  9. Thermodynamic Theory of Spherically Trapped Coulomb Clusters

    NASA Astrophysics Data System (ADS)

    Wrighton, Jeffrey; Dufty, James; Bonitz, Michael; K"{A}Hlert, Hanno

    2009-11-01

    The radial density profile of a finite number of identical charged particles confined in a harmonic trap is computed over a wide ranges of temperatures (Coulomb coupling) and particle numbers. At low temperatures these systems form a Coulomb crystal with spherical shell structure which has been observed in ultracold trapped ions and in dusty plasmas. The shell structure is readily reproduced in simulations. However, analytical theories which used a mean field approachfootnotetext[1]C. Henning et al., Phys. Rev. E 74, 056403 (2006) or a local density approximationfootnotetext[2]C. Henning et al., Phys. Rev. E 76, 036404 (2007) have, so far, only been able to reproduce the average density profile. Here we present an approach to Coulomb correlations based on the hypernetted chain approximation with additional bridge diagrams. It is demonstrated that this model reproduces the correct shell structure within a few percent and provides the basis for a thermodynamic theory of Coulomb clusters in the strongly coupled fluid state.footnotetext[3]J. Wrighton, J.W. Dufty, H. K"ahlert and M. Bonitz, J. Phys. A 42, 214052 (2009) and Phys. Rev. E (2009) (to be submitted)

  10. Coulombic Models in Chemical Bonding.

    ERIC Educational Resources Information Center

    Sacks, Lawrence J.

    1986-01-01

    Describes a bonding theory which provides a framework for the description of a wide range of substances and provides quantitative information of remarkable accuracy with far less computational effort than that required of other approaches. Includes applications, such as calculation of bond energies of two binary hydrides (methane and diborane).…

  11. Quasiequilibrium Characterization of Mixed-Ion Coulomb Crystals

    NASA Astrophysics Data System (ADS)

    Okada, Kunihiro; Ichikawa, Masanari; Wada, Michiharu; Schuessler, Hans A.

    2015-11-01

    We demonstrate the application of reliable methods to determine both the average micromotion energies and the number of sympathetically cooled ions (SCIs) embedded in mixed-ion Coulomb crystals in a linear Paul trap. The number of the SCIs and the micromotion energies for the observed mixed-ion crystals are determined by comparing experimentally obtained images with molecular-dynamics simulations, where the kinetic energies of SCIs trapped in rf fields are averaged in cold elastic collisions between the laser-cooled ions and virtual very light atoms. This combined method quickly achieves the quasiequilibrium state of large mixed Coulomb crystals with over 103 ions, regardless of the initial conditions, and shows that the previously used pseudopotential-based adiabatic approximations should be replaced by such molecular-dynamics simulations. In addition, a pattern-matching recognition procedure is introduced which objectively ascertains the number of ions. We also apply the presented characterization method to determine the reaction-rate constant between slow acetonitrile molecules and sympathetically cooled Ne+ ions at a translational temperature lower than 10 K.

  12. Remote Spacecraft Attitude Control by Coulomb Charging

    NASA Astrophysics Data System (ADS)

    Stevenson, Daan

    The possibility of inter-spacecraft collisions is a serious concern at Geosynchronous altitudes, where many high-value assets operate in proximity to countless debris objects whose orbits experience no natural means of decay. The ability to rendezvous with these derelict satellites would enable active debris removal by servicing or repositioning missions, but docking procedures are generally inhibited by the large rotational momenta of uncontrolled satellites. Therefore, a contactless means of reducing the rotation rate of objects in the space environment is desired. This dissertation investigates the viability of Coulomb charging to achieve such remote spacecraft attitude control. If a servicing craft imposes absolute electric potentials on a nearby nonspherical debris object, it will impart electrostatic torques that can be used to gradually arrest the object's rotation. In order to simulate the relative motion of charged spacecraft with complex geometries, accurate but rapid knowledge of the Coulomb interactions is required. To this end, a new electrostatic force model called the Multi-Sphere Method (MSM) is developed. All aspects of the Coulomb de-spin concept are extensively analyzed and simulated using a system with simplified geometries and one dimensional rotation. First, appropriate control algorithms are developed to ensure that the nonlinear Coulomb torques arrest the rotation with guaranteed stability. Moreover, the complex interaction of the spacecraft with the plasma environment and charge control beams is modeled to determine what hardware requirements are necessary to achieve the desired electric potential levels. Lastly, the attitude dynamics and feedback control development is validated experimentally using a scaled down terrestrial testbed. High voltage power supplies control the potential on two nearby conductors, a stationary sphere and a freely rotating cylinder. The nonlinear feedback control algorithms developed above are implemented to

  13. Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots

    NASA Astrophysics Data System (ADS)

    Keller, A. J.; Lim, J. S.; Sánchez, David; López, Rosa; Amasha, S.; Katine, J. A.; Shtrikman, Hadas; Goldhaber-Gordon, D.

    2016-08-01

    In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior.

  14. Effect of Coulomb interactions on the disorder-driven superconductor-insulator transition

    NASA Astrophysics Data System (ADS)

    Sherman, Daniel; Gorshunov, Boris; Poran, Shachaf; Trivedi, Nandini; Farber, Eli; Dressel, Martin; Frydman, Aviad

    2014-01-01

    We have studied the evolution of the superconducting energy gap of indium oxide through the disorder-driven superconductor-to-insulator transition (SIT) using two distinct experimental methods that allow us to test the influence of metallic screening: tunneling spectroscopy in which a metallic electrode is adjacent to the studied sample, thus screening Coulomb interactions, and contactless terahertz spectroscopy which probes the unperturbed sample. The tunneling measurements reveal a similar superconducting gap on both sides of the SIT and at temperatures above and below Tc. Terahertz measurements detect the superconducting gap below but not above the critical temperature nor in the insulating state. This difference between the two spectroscopy methods is attributed to the effect of Coulomb interactions which are screened in the tunneling experiments. Our study reveals the importance of Coulomb interactions on the energy gap of disordered superconductors.

  15. A Monte Carlo study of the generalized Coulomb Milne problem

    NASA Astrophysics Data System (ADS)

    Barghouthi, I. A.; Barakat, A. R.

    2005-11-01

    Because of its relevance to space plasma problems (such as the terrestrial polar wind), we investigated the diffusion of a minor ion species through a non-uniform background major ion species. A Fokker Planck expression was used to represent the Coulomb collisions between the minor and the background ions. A change of variables was implemented in order to transform the problem into a simpler form where the background medium is uniform. This transformed problem described minor ions diffusing through a background of ions with constant density in the semi-infinite region z˜⩾0 and zero density in the region z˜<0. This problem was termed the generalized Coulomb Milne problem and was addressed by a Monte Carlo simulation. Three different minor-to-background mass ratios (γ) were considered, namely γ=16, 1, and 116, which were relevant to H and O ions, the two most dominant ions in the terrestrial ionosphere. The minor ion velocity distribution (f) and the velocity moments (density (n); drift velocity (u), parallel (T) and perpendicular (T) temperatures; and parallel (q˜s∥) and perpendicular (q˜s⊥) heat fluxes) were computed. For the cases when the minor species mass was comparable to, or larger than the background species mass (γ=16,1), the distribution was close to Maxwellian at low altitudes due to Coulomb collisions, gradually formed a weak upward tail in the transition region, and eventually assumed a half-Maxwellian shape at the collisionless region. This was reflected in the enhancement of the flow and random energies, and the energy fluxes for these cases. Deep into the collision-dominated region, n was found to be linearly dependent on the normalized distance z˜ with a gradient (m=dn˜/dz˜). As γ decreased from 16 to 1 to 116, m decreased from 2.0 to 1.7 to 0.75, respectively. For the case of a lighter minor ion species drifting through a heavier background ion species (e.g. γ=116), the ion outflow exhibited some interesting qualitatively

  16. Coulomb excitation of a {sup 78}Rb radioactive beam.

    SciTech Connect

    Schwartz, J.

    1998-11-18

    In order to test the feasibility of Coulomb excitation of radioactive projectiles with low beam energies and intensities, they have produced a secondary radioactive beam of {sup 78}Rb and Coulomb re-excited it. The beam was produced in the fusion evaporation reaction {sup 24}Mg({sup 58}Ni,3pn){sup 78}Rb at a beam energy of 260 MeV, using the Argonne National Laboratory ATLAS accelerator. The residues of interest were separated from other reaction products and non-interacting beam using the Fragment Mass Analyzer (FMA). The beam leaving the FMA was {sup 78}Kr and {sup 78}Rb{sup gs,m1,m2}, which was refocused onto a {sup 58}Ni secondary target. They have extracted a spectrum of {gamma}-rays associated with re-excitation of A = 78 isobars. The re-excitation of stable {sup 78}Kr was observed, which serves as a reference. Gamma-rays associated with excitation of {sup 78}Rb{sup gs,m1,m2} were also seen. The measured yields indicate that all the {sup 78}Rb states are highly deformed.

  17. Coulomb-corrected molecular orbital tomography of nitrogen

    PubMed Central

    Zhai, Chunyang; He, Lixin; Lan, Pengfei; Zhu, Xiaosong; Li, Yang; Wang, Feng; Shi, Wenjing; Zhang, Qingbin; Lu, Peixiang

    2016-01-01

    High-order harmonic generation (HHG) from aligned molecules has provided a promising way to probe the molecular orbital with an Ångström resolution. This method, usually called molecular orbital tomography (MOT) replies on a simple assumption of the plane-wave approximation (PW), which has long been questioned due to that PW approximation is known to be valid in the keV energy region. However, the photon energy is usually no more than 100 eV in HHG. In this work, we experimentally reconstruct the highest occupied molecular orbital (HOMO) of nitrogen (N2) by using a Coulomb-corrected MOT (CCMOT) method. In our scheme, the molecular continuum states are described by a Coulomb wave function instead of the PW approximation. With CCMOT, the reconstructed orbital is demonstrated to agree well with the theoretical prediction and retain the main features of the HOMO of N2. Compared to the PW approximation method, the CCMOT shows a significant improvement in eliminating the artificial structures caused by PW approximation. PMID:27000666

  18. Coulomb-corrected molecular orbital tomography of nitrogen

    NASA Astrophysics Data System (ADS)

    Zhai, Chunyang; He, Lixin; Lan, Pengfei; Zhu, Xiaosong; Li, Yang; Wang, Feng; Shi, Wenjing; Zhang, Qingbin; Lu, Peixiang

    2016-03-01

    High-order harmonic generation (HHG) from aligned molecules has provided a promising way to probe the molecular orbital with an Ångström resolution. This method, usually called molecular orbital tomography (MOT) replies on a simple assumption of the plane-wave approximation (PW), which has long been questioned due to that PW approximation is known to be valid in the keV energy region. However, the photon energy is usually no more than 100 eV in HHG. In this work, we experimentally reconstruct the highest occupied molecular orbital (HOMO) of nitrogen (N2) by using a Coulomb-corrected MOT (CCMOT) method. In our scheme, the molecular continuum states are described by a Coulomb wave function instead of the PW approximation. With CCMOT, the reconstructed orbital is demonstrated to agree well with the theoretical prediction and retain the main features of the HOMO of N2. Compared to the PW approximation method, the CCMOT shows a significant improvement in eliminating the artificial structures caused by PW approximation.

  19. Coulomb-corrected molecular orbital tomography of nitrogen.

    PubMed

    Zhai, Chunyang; He, Lixin; Lan, Pengfei; Zhu, Xiaosong; Li, Yang; Wang, Feng; Shi, Wenjing; Zhang, Qingbin; Lu, Peixiang

    2016-01-01

    High-order harmonic generation (HHG) from aligned molecules has provided a promising way to probe the molecular orbital with an Ångström resolution. This method, usually called molecular orbital tomography (MOT) replies on a simple assumption of the plane-wave approximation (PW), which has long been questioned due to that PW approximation is known to be valid in the keV energy region. However, the photon energy is usually no more than 100 eV in HHG. In this work, we experimentally reconstruct the highest occupied molecular orbital (HOMO) of nitrogen (N2) by using a Coulomb-corrected MOT (CCMOT) method. In our scheme, the molecular continuum states are described by a Coulomb wave function instead of the PW approximation. With CCMOT, the reconstructed orbital is demonstrated to agree well with the theoretical prediction and retain the main features of the HOMO of N2. Compared to the PW approximation method, the CCMOT shows a significant improvement in eliminating the artificial structures caused by PW approximation. PMID:27000666

  20. Unsafe coulomb excitation of {sup 240-244}Pu.

    SciTech Connect

    Wiedenhoever, I.

    1998-12-01

    The high spin states of {sup 240}Pu and {sup 244}Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a {sup 208}Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to {sup 242}Pu were obtained as well. In the case of {sup 244}Pu, the yrast band was extended to 34{h_bar}, revealing the completed {pi}i{sub 13/2} alignment, a ''first'' for actinide nuclei. The yrast sequence of {sup 242}Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of {sup 240}Pu was measured up to the highest rotational frequencies ever reported in the actinide region ({approximately} 300 keV), no sign of particle alignment was observed. In this case, several observables such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or suppressing the {pi}i{sub 13/2} particle alignment.

  1. Coulomb and nuclear excitations of narrow resonances in 17Ne

    NASA Astrophysics Data System (ADS)

    Marganiec, J.; Wamers, F.; Aksouh, F.; Aksyutina, Yu.; Álvarez-Pol, H.; Aumann, T.; Beceiro-Novo, S.; Bertulani, C. A.; Boretzky, K.; Borge, M. J. G.; Chartier, M.; Chatillon, A.; Chulkov, L. V.; Cortina-Gil, D.; Emling, H.; Ershova, O.; Fraile, L. M.; Fynbo, H. O. U.; Galaviz, D.; Geissel, H.; Heil, M.; Hoffmann, D. H. H.; Hoffmann, J.; Johansson, H. T.; Jonson, B.; Karagiannis, C.; Kiselev, O. A.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Langer, C.; Lantz, M.; Le Bleis, T.; Lemmon, R.; Litvinov, Yu. A.; Mahata, K.; Müntz, C.; Nilsson, T.; Nociforo, C.; Nyman, G.; Ott, W.; Panin, V.; Paschalis, S.; Perea, A.; Plag, R.; Reifarth, R.; Richter, A.; Rodriguez-Tajes, C.; Rossi, D.; Riisager, K.; Savran, D.; Schrieder, G.; Simon, H.; Stroth, J.; Sümmerer, K.; Tengblad, O.; Typel, S.; Weick, H.; Wiescher, M.; Wimmer, C.

    2016-08-01

    New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the 15O + p + p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of data from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. The resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure.

  2. Coulomb Screening and Coherent Phonon in Methylammonium Lead Iodide Perovskites.

    PubMed

    Wang, He; Valkunas, Leonas; Cao, Thu; Whittaker-Brooks, Luisa; Fleming, Graham R

    2016-08-18

    Methylammonium lead iodide (CH3NH3PbI3) hybrid perovskite in the tetragonal and orthorhombic phases have different exciton binding energies and demonstrate different excitation kinetics. Here, we explore the role that crystal structure plays in the kinetics via fluence dependent transient absorption spectroscopy. We observe stronger saturation of the free carrier concentration under high pump energy density in the orthorhombic phase relative to the tetragonal phase. We attribute this phenomenon to small dielectric constant, large exciton binding energy, and weak Coulomb screening, which results in difficult exciton dissociation under high light intensity in the orthorhombic phase. At higher excitation intensities, we observe a coherent phonon with an oscillation frequency of 23.4 cm(-1) at 77 K, whose amplitude tracks the increase of the first-order lifetime. PMID:27485190

  3. The accuracy of the Gaussian-and-finite-element-Coulomb (GFC) method for the calculation of Coulomb integrals

    NASA Astrophysics Data System (ADS)

    Przybytek, Michal; Helgaker, Trygve

    2013-08-01

    We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (γH = 2) and eight (γ1st = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (α _min^G=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d4 with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step—namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems

  4. The accuracy of the Gaussian-and-finite-element-Coulomb (GFC) method for the calculation of Coulomb integrals.

    PubMed

    Przybytek, Michal; Helgaker, Trygve

    2013-08-01

    We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (γ(H) = 2) and eight (γ(1st) = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (αmin (G)=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d(4) with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step-namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems

  5. Coulomb crystallization of highly charged ions

    NASA Astrophysics Data System (ADS)

    Schmöger, L.; Versolato, O. O.; Schwarz, M.; Kohnen, M.; Windberger, A.; Piest, B.; Feuchtenbeiner, S.; Pedregosa-Gutierrez, J.; Leopold, T.; Micke, P.; Hansen, A. K.; Baumann, T. M.; Drewsen, M.; Ullrich, J.; Schmidt, P. O.; López-Urrutia, J. R. Crespo

    2015-03-01

    Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically 40Ar13+) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be+ ions. We also demonstrate cooling of a single Ar13+ ion by a single Be+ ion—the prerequisite for quantum logic spectroscopy with a potential 10-19 accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.

  6. Coulomb drag in topological insulator films

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Liu, Weizhe Edward; Culcer, Dimitrie

    2016-05-01

    We study Coulomb drag between the top and bottom surfaces of topological insulator films. We derive a kinetic equation for the thin-film spin density matrix containing the full spin structure of the two-layer system, and analyze the electron-electron interaction in detail in order to recover all terms responsible for Coulomb drag. Focusing on typical topological insulator systems, with a film thicknesses d up to 6 nm, we obtain numerical and approximate analytical results for the drag resistivity ρD and find that ρD is proportional to T2d-4 na-3/2 np-3/2 at low temperature T and low electron density na,p, with a denoting the active layer and p the passive layer. In addition, we compare ρD with graphene, identifying qualitative and quantitative differences, and we discuss the multi-valley case, ultra thin films and electron-hole layers.

  7. Coulomb wave functions in momentum space

    DOE PAGESBeta

    Eremenko, V; Upadhyay, N. J.; Thompson, I J; Elster, Charlotte; Nunes, F. M.; Arbanas, Goran; Escher, J.E.; Hlophe, L.

    2015-01-01

    An algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space is presented. The arguments are the Sommerfeld parameter eta, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p -> q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of vertical bar eta vertical barmore » in the range of 10(-1) to 10, and thus is particularly suited for momentum space calculations of nuclear reactions. Program Summary Program title: libcwfn Catalogue identifier: AEUQ_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEUQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 864503 No. of bytes in distributed program, including test data, etc.: 7178021 Distribution format: tar.gz Programming language: Fortran 90, Fortran 77, Python, make (GNU Make dialect), GNU Bash shell interpreter (available as /bin/bash). Computer: Apple Powermac (Intel Xeon), ASUS K53U (AMD E-350 (Dual Core)), DELL Precision T3500 (Intel Xeon), NERSC Carver (Intel Nehalem Quad Core). Operating system: Linux, Windows (using Cygwin). RAM: less than 512 Mbytes Classification: 17.8, 17.13, 17.16. Nature of problem: The calculation of partial wave Coulomb functions with integer land all other arguments real. Solution method: Computing the value of the function using explicit formulae and algorithms. Running time: Less than 10(-3) s. (C) 2014 Elsevier B.V. All rights reserved.« less

  8. Coulomb wave functions in momentum space

    SciTech Connect

    Eremenko, V; Upadhyay, N. J.; Thompson, I J; Elster, Charlotte; Nunes, F. M.; Arbanas, Goran; Escher, J.E.; Hlophe, L.

    2015-01-01

    An algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space is presented. The arguments are the Sommerfeld parameter eta, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p -> q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of vertical bar eta vertical bar in the range of 10(-1) to 10, and thus is particularly suited for momentum space calculations of nuclear reactions. Program Summary Program title: libcwfn Catalogue identifier: AEUQ_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEUQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 864503 No. of bytes in distributed program, including test data, etc.: 7178021 Distribution format: tar.gz Programming language: Fortran 90, Fortran 77, Python, make (GNU Make dialect), GNU Bash shell interpreter (available as /bin/bash). Computer: Apple Powermac (Intel Xeon), ASUS K53U (AMD E-350 (Dual Core)), DELL Precision T3500 (Intel Xeon), NERSC Carver (Intel Nehalem Quad Core). Operating system: Linux, Windows (using Cygwin). RAM: less than 512 Mbytes Classification: 17.8, 17.13, 17.16. Nature of problem: The calculation of partial wave Coulomb functions with integer land all other arguments real. Solution method: Computing the value of the function using explicit formulae and algorithms. Running time: Less than 10(-3) s. (C) 2014 Elsevier B.V. All rights reserved.

  9. Ultrashort pulses in graphene with Coulomb impurities

    NASA Astrophysics Data System (ADS)

    Konobeeva, N. N.; Belonenko, M. B.

    2016-06-01

    We have investigated the propagation of an electromagnetic field in graphene with impurities, including the two-dimensional case. The spectrum of electrons for the graphene subsystem is taken from a model that takes into account Coulomb impurities. Based on Maxwell's equations, we have obtained an effective equation for the vector potential of the electromagnetic field. It has been revealed that the pulse shape depends on free parameters.

  10. The scattering of the screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Cao, Xin-Wei; Chen, Wen-Li; Li, Yuan-Yuan; Wei, Gao-Feng

    2014-08-01

    We study the scattering states of the screened Coulomb potential in the nonrelativistic frame. The explicitly calculation formula of phase shift is derived and the normalized radial wave functions of scattering states on the ^{\\prime} k/2\\pi scale^{\\prime} are presented. By studying analytical properties of scattering amplitude the screening effects on bound states are discussed numerically. It is shown that the screening effects increase with increasing screened parameter, especially for large quantum states.

  11. Wannier function approach to realistic Coulomb interactions in layered materials and heterostructures

    NASA Astrophysics Data System (ADS)

    Rösner, M.; Şaşıoǧlu, E.; Friedrich, C.; Blügel, S.; Wehling, T. O.

    2015-08-01

    We introduce an approach to derive realistic Coulomb interaction terms in freestanding layered materials and vertical heterostructures from ab initio modeling of the corresponding bulk materials. To this end, we establish a combination of calculations within the framework of the constrained random-phase approximation, Wannier function representation of Coulomb matrix elements within some low-energy Hilbert space, and continuum medium electrostatics, which we call Wannier function continuum electrostatics (WFCE). For monolayer and bilayer graphene we reproduce full ab initio calculations of the Coulomb matrix elements within an accuracy of 0.3 eV or better. We show that realistic Coulomb interactions in bilayer graphene can be manipulated on the eV scale by different dielectric and metallic environments. A comparison to electronic phase diagrams derived in M. M. Scherer et al. [Phys. Rev. B 85, 235408 (2012), 10.1103/PhysRevB.85.235408] suggests that the electronic ground state of bilayer graphene is a layered antiferromagnet and remains surprisingly unaffected by these strong changes in the Coulomb interaction.

  12. "Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.

    1999-01-01

    The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this

  13. Computational Analysis of Intermolecular Coulombic Decay Effects in DNA nucleotide Photoionization

    NASA Astrophysics Data System (ADS)

    Vargas, E. L.; Robertson, J.; Andrianarijaona, V. M.

    2016-03-01

    Intermolecular Coulombic Decay (ICD) is the process of how electrons return to their original state after excitation and how this affects their immediate environment. In a previous research presentationwe had considered the hypothetical applications of Intermolecular Coulombic Decay on the adhesiveness of coding proteins within DNA molecules. This presentation is a continuation of the previous in that the results of our DFT-based computational calculations of the ionization potentials of nucleotides and their excitation energies will be presented, as well as how they influence their surroundings. Author would like to acknowledge the PUC Student Senate for financial assistance.

  14. Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Datta Pramanik, U.; Aumann, T.; Beceiro, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chatterjee, S.; Chartier, M.; Cortina-Gil, D.; De Angelis, G.; Gonzalez-Diaz, D.; Emling, H.; Diaz Fernandez, P.; Fraile, L. M.; Ershova, O.; Geissel, H.; Heil, M.; Jonson, B.; Kelic, A.; Johansson, H.; Kruecken, R.; Kroll, T.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Munzenberg, G.; Marganiec, J.; Nociforo, C.; Najafi, A.; Panin, V.; Paschalis, S.; Pietri, S.; Plag, R.; Rahaman, A.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Ray, J.; Simon, H.; Scheidenberger, C.; Typel, S.; Taylor, J.; Togano, Y.; Volkov, V.; Weick, H.; Wagner, A.; Wamers, F.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2014-03-01

    Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s)⊗νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al.

  15. A shortcut through the Coulomb gas method for spectral linear statistics on random matrices

    NASA Astrophysics Data System (ADS)

    Deelan Cunden, Fabio; Facchi, Paolo; Vivo, Pierpaolo

    2016-04-01

    In the last decade, spectral linear statistics on large dimensional random matrices have attracted significant attention. Within the physics community, a privileged role has been played by invariant matrix ensembles for which a two-dimensional Coulomb gas analogy is available. We present a critical revision of the Coulomb gas method in random matrix theory (RMT) borrowing language and tools from large deviations theory. This allows us to formalize an equivalent, but more effective and quicker route toward RMT free energy calculations. Moreover, we argue that this more modern viewpoint is likely to shed further light on the interesting issues of weak phase transitions and evaporation phenomena recently observed in RMT.

  16. Multiple nucleon knockout by Coulomb dissociation in relativistic heavy-ion collisions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Norbury, John W.; Townsend, Lawrence W.

    1988-01-01

    The Coulomb dissociation contributions to fragmentation cross sections in relativistic heavy ion collisions, where more than one nucleon is removed, are estimated using the Weizsacker-Williams method of virtual quanta. Photonuclear cross sections taken from experimental results were used to fold into target photon number spectra calculated with the Weizsacker-Williams method. Calculations for several projectile target combinations over a wide range of charge numbers, and a wide range of incident projectile energies, are reported. These results suggest that multiple nucleon knockout by the Coulomb field may be of negligible importance in galactic heavy ion studies for projectiles lighter than Fe-56.

  17. Double-island Coulomb blockade in (Ga,Mn)As nanoconstrictions

    NASA Astrophysics Data System (ADS)

    Geißler, S.; Pfaller, S.; Utz, M.; Bougeard, D.; Donarini, A.; Grifoni, M.; Weiss, D.

    2015-05-01

    We report on a systematic study of the Coulomb-blockade effects in nanofabricated narrow constrictions in thin (Ga,Mn)As films. Different low-temperature transport regimes have been observed for decreasing constriction sizes: the Ohmic, the single-electron tunneling (SET), and a completely insulating regime. In the SET, complex stability diagrams with nested Coulomb diamonds and anomalous conductance suppression in the vicinity of charge degeneracy points have been observed. We rationalize these observations in the SET with a double ferromagnetic island model coupled to ferromagnetic leads. Its transport characteristics are analyzed in terms of a modified orthodox theory of Coulomb blockade which takes into account the energy dependence of the density of states in the metallic islands.

  18. Effect of Coulomb scattering on low-pressure high-density electronegative discharges.

    PubMed

    Kawamura, E; Birdsall, C K

    2005-02-01

    For electronegative plasmas with low gas pressure and high ion densities, we expect Coulomb collisions between positive and negative ions to dominate over collisions between ions and neutrals. We incorporated Nanbu's cumulative small-angle collision method [K. Nanbu, Phys. Rev. E, 55, 4642 (1997)] into our one-dimensional three-velocity-component particle-in-cell code PDP1 in order to study the effect of Coulomb collisions on low pressure high density electronegative discharges. Nanbu's method treats a succession of small-angle binary collisions as a single binary collision with a large scattering angle, which is far faster than treating each individual small-angle collision. We find that Coulomb collisions between positive and negative ions in low-pressure high-density electronegative discharges significantly modify the negative ion flux, density, and kinetic energy profiles. PMID:15783425

  19. Effect of Coulomb scattering on low-pressure high-density electronegative discharges

    SciTech Connect

    Kawamura, E.; Birdsall, C.K.

    2005-02-01

    For electronegative plasmas with low gas pressure and high ion densities, we expect Coulomb collisions between positive and negative ions to dominate over collisions between ions and neutrals. We incorporated Nanbu's cumulative small-angle collision method [K. Nanbu, Phys. Rev. E, 55, 4642 (1997)] into our one-dimensional three-velocity-component particle-in-cell code PDP1 in order to study the effect of Coulomb collisions on low pressure high density electronegative discharges. Nanbu's method treats a succession of small-angle binary collisions as a single binary collision with a large scattering angle, which is far faster than treating each individual small-angle collision. We find that Coulomb collisions between positive and negative ions in low-pressure high-density electronegative discharges significantly modify the negative ion flux, density, and kinetic energy profiles.

  20. Coulomb excitation of 44Ca and 46Ar

    NASA Astrophysics Data System (ADS)

    Calinescu, S.; Cáceres, L.; Grévy, S.; Sorlin, O.; Dombrádi, Z.; Stanoiu, M.; Astabatyan, R.; Borcea, C.; Borcea, R.; Bowry, M.; Catford, W.; Clément, E.; Franchoo, S.; Garcia, R.; Gillibert, R.; Guerin, I. H.; Kuti, I.; Lukyanov, S.; Lepailleur, A.; Maslov, V.; Morfouace, P.; Mrazek, J.; Negoita, F.; Niikura, M.; Perrot, L.; Podolyák, Z.; Petrone, C.; Penionzhkevich, Y.; Roger, T.; Rotaru, F.; Sohler, D.; Stefan, I.; Thomas, J. C.; Vajta, Z.; Wilson, E.

    2016-04-01

    The reduced transition probabilities B (E 2 ;0g.s . +→21+) of the 46Ar and 44Ca nuclei were studied using the Coulomb excitation technique at intermediate energy at the LISE/GANIL facility. The in-flight γ rays, emitted after the Coulomb excitation of their first 2+ states, were detected in an array of 64 BaF2 crystals. The present B(E 2 ↑ ) value for 44Ca, 475(36) e2fm4 , agrees well with the value of 495(35) e2fm4 obtained by averaging results of previous experiments. Consistent B (E 2 ;0g.s . +→21+) values of 225(29) e2fm4 and 234(19) e2fm4 have been obtained for 46Ar from an absolute and a relative measurement, normalized to the 44Ca value. Both results agree with the ones obtained with the same experimental technique at the NSCL facility but are a factor of 2 smaller than the shell model predictions. The drop in B (E 2 ;0g.s . +→21+) in the Ar chain at N =28 , confirmed in this experiment, shows that 46Ar is sensitive to the N =28 shell closure.

  1. Coulomb attraction in the optical spectra of quantum disks

    NASA Astrophysics Data System (ADS)

    Adolph, B.; Glutsch, S.; Bechstedt, F.

    1993-11-01

    In this paper we present a theory that describes the influence of the Coulomb interaction between electrons and holes on the optical spectra of flat quantum dots within the envelope-function formalism. Starting from a nonlocal Elliott-like formula, absorption and luminescence characteristics are traced back to properties of two-particle wave functions and energies, which are solutions of the corresponding Schrödinger equation for an electron-hole pair under the influence of the Coulomb attraction and confinement potentials, determined by the spatial variation of the band edges of the considered microstructure. We present a complete numerical solution of the two-particle problem for flat quantum dots, i.e., disks for which the size quantization in the growth direction is much stronger than that in the perpendicular plane. The resulting theoretical line shapes are compared with luminescence spectra obtained recently for quantum dots fabricated by laser-induced thermal cation interdiffusion in quantum-well structures.

  2. Coulomb interaction effect in tilted Weyl fermion in two dimensions

    NASA Astrophysics Data System (ADS)

    Isobe, Hiroki; Nagaosa, Naoto

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)2I3 and three-dimensional WTe2. The Coulomb interaction between electrons modifies the velocities in an essential way in the low energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the velocity of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  3. Coulomb blockade in low-mobility nanometer size Si MOSFET's

    NASA Astrophysics Data System (ADS)

    Sanquer, M.; Specht, M.; Ghenim, L.; Deleonibus, S.; Guegan, G.

    2000-03-01

    We investigate coherent transport in Si metal-oxide-semiconductor field-effect transistors with nominal gate lengths 50-100 nm and various widths at very low temperature. Independent of the geometry, localized states appear when G~=e2/h and transport is dominated by resonant tunnelling through a single quantum dot formed by an impurity potential. We find that the typical size of the relevant impurity quantum dot is comparable to the channel length and that the periodicity of the observed Coulomb blockade oscillations is roughly inversely proportional to the channel length. The spectrum of resonances and the nonlinear I-V curves allow us to measure the charging energy and the mean level energy spacing for electrons in the localized state. Furthermore, we find that in the dielectric regime the variance var(lng) of the logarithmic conductance lng is proportional to its average value consistent with one-electron scaling models.

  4. Coulomb explosion of CS2 molecule under an intense femtosecond laser field

    NASA Astrophysics Data System (ADS)

    Xiao, Wang; Jian, Zhang; Shi-An, Zhang; Zhen-Rong, Sun

    2016-05-01

    We experimentally demonstrate the Coulomb explosion process of CS2 molecule under a near-infrared (800 nm) intense femtosecond laser field by a DC-sliced ion imaging technique. We obtain the DC-sliced images of these fragment ions S+, S2+, CS+, and CS2+ by breaking one C–S bond, and assign their Coulomb explosion channels by considering their kinetic energy release and angular distribution. We also numerically simulate the dissociation dynamics of parent ions by a Coulomb potential approximation, and obtain the time evolution of Coulomb energy and kinetic energy release, which indicates that the dissociation time of parent ions decreases with the increase of the charge number k. These experimental and theoretical results can serve as a useful benchmark for those researchers who work in the related area. Project supported by the National Natural Science Foundation of China (Grant Nos. 51132004 and 11474096), and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14JC1401500). We acknowledge the support of the NYU-ECNU Institute of Physics at NYU Shanghai, China.

  5. Coulomb problem in non-commutative quantum mechanics

    SciTech Connect

    Galikova, Veronika; Presnajder, Peter

    2013-05-15

    The aim of this paper is to find out how it would be possible for space non-commutativity (NC) to alter the quantum mechanics (QM) solution of the Coulomb problem. The NC parameter {lambda} is to be regarded as a measure of the non-commutativity - setting {lambda}= 0 which means a return to the standard quantum mechanics. As the very first step a rotationally invariant NC space R{sub {lambda}}{sup 3}, an analog of the Coulomb problem configuration space (R{sup 3} with the origin excluded) is introduced. R{sub {lambda}}{sup 3} is generated by NC coordinates realized as operators acting in an auxiliary (Fock) space F. The properly weighted Hilbert-Schmidt operators in F form H{sub {lambda}}, a NC analog of the Hilbert space of the wave functions. We will refer to them as 'wave functions' also in the NC case. The definition of a NC analog of the hamiltonian as a hermitian operator in H{sub {lambda}} is one of the key parts of this paper. The resulting problem is exactly solvable. The full solution is provided, including formulas for the bound states for E < 0 and low-energy scattering for E > 0 (both containing NC corrections analytic in {lambda}) and also formulas for high-energy scattering and unexpected bound states at ultra-high energy (both containing NC corrections singular in {lambda}). All the NC contributions to the known QM solutions either vanish or disappear in the limit {lambda}{yields} 0.

  6. Coulomb field in a constant electromagnetic background

    NASA Astrophysics Data System (ADS)

    Adorno, T. C.; Gitman, D. M.; Shabad, A. E.

    2016-06-01

    Nonlinear Maxwell equations are written up to the third-power deviations from a constant-field background, valid within any local nonlinear electrodynamics including QED with a Euler-Heisenberg (EH) effective Lagrangian. The linear electric response to an imposed static finite-sized charge is found in the vacuum filled by an arbitrary combination of constant and homogeneous electric and magnetic fields. The modified Coulomb field and corrections to the total charge and to the charge density are given in terms of derivatives of the effective Lagrangian with respect to the field invariants. These are specialized for the EH Lagrangian.

  7. Spatio-temporal correlations in Coulomb clusters

    NASA Astrophysics Data System (ADS)

    Ash, Biswarup; Chakrabarti, J.; Ghosal, Amit

    2016-05-01

    The dynamical responses of Coulomb-interacting particles in two-dimensional nanoclusters are analyzed at different temperatures characterizing their solid- and liquid-like behavior. Depending on the trap symmetry, spatial correlations undergo slow, stretched exponential relaxations at long times, arising from spatially correlated motion in string-like paths. Such results stem from the combined effects of confinement and long-range repulsion, making the systems inherently heterogeneous. While particles in a “solid” flow produce dynamic heterogeneities, motion in “liquid” yields an unusually long tail in the distribution of particle displacements. A phenomenological model captures much of the subtleties of our numerical simulations.

  8. Coulomb Repulsion in Miniature Ion Mobility Spectrometry

    SciTech Connect

    Xu, J.; Whitten, W.B.; Ramsey, J.M.

    1999-08-08

    We have undertaken a study of ion mobility resolution in a miniature ion mobility spectrometer with a drift channel 1.7 mm in diameter and 35 mm in length. The device attained a maximum resolution of 14 in separating ions of NO, O{sub 2}, and methyl iodine. The ions were generated by pulses from a frequency-quadrupled Nd:YAG laser. Broadening due to Coulomb repulsion was modeled theoretically and shown experimentally to have a major effect on the resolution of the miniature device.

  9. Coulomb sum rule for {sup 4}He

    SciTech Connect

    J. Carlson; J. Jourdan; R. Schiavilla; I. Sick

    2002-10-01

    We determine the Coulomb sum for {sup 4}He using world data on {sup 4}He(e, e') and compare the results to calculations based on realistic interactions and including two-body components in the nuclear charge operator. We find good agreement between theory and experiment using free-nucleon form factors. The apparent reduction of the in-medium G{sub ep} implied by IA-interpretation of the L/T-ratios measured in {sup 4}He(e,e'p) and {sup 4}He([vec]e, e'p) is not confirmed.

  10. "Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

    NASA Astrophysics Data System (ADS)

    Marshall, J. R.

    1999-09-01

    The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this