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Sample records for isotopes coulomb excitation

  1. Coulomb excitation of radioactive {sup 79}Pb

    SciTech Connect

    Lister, C.J.; Blumenthal, D.; Davids, C.N.

    1995-08-01

    The technical challenges expected in experiments with radioactive beams can already be explored by using ions produced in primary reactions. In addition, the re-excitation of these ions by Coulomb excitation allows a sensitive search for collective states that are well above the yrast line. We are building an experiment to study Coulomb excitation of radioactive ions which are separated from beam particles by the Fragment Mass Analyzer. An array of gamma detectors will be mounted at the focal plane to measure the gamma radiation following re-excitation. Five Compton-suppressed Ge detectors and five planar LEPS detectors will be used. The optimum experiment of this type appears to be the study of {sup 79}Rb following the {sup 24}Mg ({sup 58}Ni,3p) reaction. We calculate that about 5 x 10{sup 5} {sup 79}Rb nuclei/second will reach the excitation foil. This rubidium isotope was selected for study as it is strongly produced and is highly deformed, so easily re-excited. The use of a {sup 58}Ni re-excitation foil offers the best yields. After re-excitation the ions will be subsequently transported into a shielded beamdump to prevent the accumulation of activity.

  2. Coulomb excitation of {sup 189}Os

    SciTech Connect

    Seale, W.A.; Botelho, S.; Ribas, R.V.

    1993-10-01

    The transitional nucleus {sup 189}Os has been studied by Coulomb excitation. Measurements with a Ge(HP) detector were made at 0{degrees}, 55{degrees}, 90{degrees} with beams of {sup 28}Si at 80 and 88 Me {sup 35}Cl at 80 MeV and {sup 16}O at 58 MeV. A total of gamma-ray transitions leading to 23 levels we used in the least-squares code GOSIA to determined reduced matrix elements. A theoretic understanding of this nucleus has been attempt from the point of view of current nuclear mode as they apply to systematics of the 1/2 {sup -}[510] 3/2 -[512], 1/2 [503] levels in this ma region.

  3. 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.

  4. 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.

  5. Characterizing intra-exciton Coulomb scattering in terahertz excitations

    SciTech Connect

    Zybell, S.; Eßer, F.; Helm, M.; Bhattacharyya, J.; Winnerl, S.; Schneider, H.; Schneebeli, L.; Böttge, C. N.; Kira, M.; Koch, S. W.; Andrews, A. M.; Strasser, G.

    2014-11-17

    An intense terahertz field is applied to excite semiconductor quantum wells yielding strong non-equilibrium exciton distributions. Even though the relaxation channels involve a complicated quantum kinetics of Coulomb and phonon effects, distinct relaxation signatures of Coulomb scattering are identified within time-resolved photoluminescence by comparing the experiment with a reduced model that contains all relevant microscopic processes. The analysis uncovers a unique time scale for the Coulomb scattering directly from experiments and reveals the influence of phonon relaxation as well as radiative decay.

  6. 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.

  7. 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.

  8. Coulomb excitation of exotic nuclei at the R3B-LAND setup

    NASA Astrophysics Data System (ADS)

    Rossi, D. M.; Adrich, P.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Böhmer, M.; Boretzky, K.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Datta Pramanik, U.; Emling, H.; Ershova, O.; Fernandez-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H.; Junghans, A.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Kurz, N.; Labiche, M.; Le Bleis, T.; Lemmon, R.; Litvinov, Yu A.; Mahata, K.; Maierbeck, P.; Movsesyan, A.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.

    2013-03-01

    Exotic Ni isotopes have been measured at the R3B-LAND setup at GSI in Darmstadt, using Coulomb excitation in inverse kinematics at beam energies around 500 MeV/u. As the experimental setup allows kinematically complete measurements, the excitation energy was reconstructed using the invariant mass method. The GDR and additional low-lying strength have been observed in 68Ni, the latter exhausting 4.1(1.9)% of the E1 energy-weighted sum rule. Also, the branching ratio for the non-statistical decay of the excited 68Ni nuclei was measured and amounts to 24(4)%.

  9. Unique and complementary information on shape coexistence in the neutron-deficient Pb region derived from Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Wrzosek-Lipska, K.; Gaffney, L. P.

    2016-02-01

    Neutron-deficient isotopes of Pt-Hg-Pb-Po-Rn are the classic region in the investigation of shape coexistence in atomic nuclei. A large programme of Coulomb-excitation experiments has been undertaken at the REX-ISOLDE facility in CERN with a number of even-even isotopes in this region. These experiments have been used to probe the electromagnetic properties of yrast and non-yrast states of even-even exotic nuclei, above and below Z = 82. Amongst a large amount of different complementary techniques used to study nuclear structure, Coulomb excitation brings substantial and unique information detailing shape coexistence. In this paper we review the Coulomb-excitation campaign at REX-ISOLDE in the light-lead region together with most recently obtained results. Furthermore, we present some new interpretations that arise from this data and show testing comparisons to state-of-the-art nuclear models.

  10. 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.

  11. 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.

  12. 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.

  13. 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)

  14. 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.

  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. 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.

  17. 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.

  18. Coulomb excitation of 124,126,128Sn(Z = 50)

    SciTech Connect

    Allmond, James M; Radford, David C; Baktash, Cyrus; Batchelder, J. C.; Galindo-Uribarri, Alfredo {nmn}; Gross, Carl J; Hausladen, Paul; Lagergren, Karin B; Larochelle, Y.; Padilla-Rodal, Elizabeth; Yu, Chang-Hong

    2011-01-01

    High-precision measurements of <0_1||E2||2_1> matrix elements from the Coulomb excitation of 124,126,128Sn(Z = 50) impinging on a 12C target are presented. The <0_1||E2||2_1> matrix elements and related B(E2) values decrease monotonically as the N = 82 shell closure is approached from N = 74 to 78, despite a near constancy in the first 2+ level energy, E(2_1+). Furthermore, results are presented for the Coulomb excitation of 124,126,128Sn using an enriched 50Ti target, which, combined with the results from the 12C target, provide a measure of the <2_1||E2||2_1> matrix elements and related static quadrupole moments, Q(2_1+) (expected to be ~0 for a spherical shape). These new results indicate that the Sn isotopes have a deformation consistent with zero. The present study marks the first report on measured 2_1+ static quadrupole moments for the unstable Sn isotopes.

  19. Cold chemistry with electronically excited Ca+ Coulomb crystals.

    PubMed

    Gingell, Alexander D; Bell, Martin T; Oldham, James M; Softley, Timothy P; Harvey, Jeremy N

    2010-11-21

    Rate constants for chemical reactions of laser-cooled Ca(+) ions and neutral polar molecules (CH(3)F, CH(2)F(2), or CH(3)Cl) have been measured at low collision energies (/k(B)=5-243 K). Low kinetic energy ensembles of (40)Ca(+) ions are prepared through Doppler laser cooling to form "Coulomb crystals" in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca(+) ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of (40)Ca(+) involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state ((2)S(1/2)) and the combined excited states ((2)D(3/2) and (2)P(1/2)) of (40)Ca(+). These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories. PMID:21090857

  20. Cold chemistry with electronically excited Ca+ Coulomb crystals

    NASA Astrophysics Data System (ADS)

    Gingell, Alexander D.; Bell, Martin T.; Oldham, James M.; Softley, Timothy P.; Harvey, Jeremy N.

    2010-11-01

    Rate constants for chemical reactions of laser-cooled Ca+ ions and neutral polar molecules (CH3F, CH2F2, or CH3Cl) have been measured at low collision energies (⟨Ecoll⟩/kB=5-243 K). Low kinetic energy ensembles of C40a+ ions are prepared through Doppler laser cooling to form "Coulomb crystals" in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca+ ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of C40a+ involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state (S21/2) and the combined excited states (D23/2 and P21/2) of C40a+. These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.

  1. Lifetime and g-factor measurements of excited states using Coulomb excitation and alpha transfer reactions

    NASA Astrophysics Data System (ADS)

    Guevara, Z. E.; Torres, D. A.

    2016-07-01

    In this contribution the challenges in the use of a setup to simultaneously measure lifetimes and g-factor values will be presented. The simultaneous use of the transient field technique and the Doppler Shift Attenuation Method, to measure magnetic moments and lifetimes respectively, allows to obtain a complete characterization of the currents of nucleons and the deformation in excited states close to the ground state. The technique is at the moment limited to Coulomb excitation and alpha-transfer reactions, what opens an interesting perspective to consider this type of experiments with radioactive beams. The use of deep-inelastic and fusion-evaporation reactions will be discussed. An example of a setup that makes use of a beam of 106Cd to study excited states of 110Sn and the beam nuclei itself will be presented.

  2. Coulomb Excitation and One-Neutron Transfer Studies of Stable and Radioactive Nuclei at HRIBF-ORNL

    SciTech Connect

    Allmond, James M

    2015-01-01

    Several stable and radioactive nuclei ranging from $A=58$ to 208 were recently studied in inverse kinematics by Coulomb excitation and heavy-ion induced one-neutron transfer at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory. These studies used a CsI-HPGe detector array to detect scattered charged particles and emitted $\\gamma$ rays from the in-beam reactions. A Bragg-curve detector was used to measure the energy loss of the various beams through the targets and to measure the radioactive beam compositions. Stable nickel, strontium, zirconium, molybdenum, tin, tellurium, and lead isotopes and neutron-rich radioactive tin and tellurium isotopes were among the nuclei recently studied. Coulomb excitation was used to measure the electromagnetic moments of the first excited states and heavy-ion induced one-neutron transfer was used to measure the absolute cross sections and lifetimes of the excited single-particle states. A sample of these results are presented here with an emphasis on the tin isotopes. In particular, a survey of the Bragg-curve measurements, Doppler corrections, and inconclusive $i_{13/2}$ candidate in $^{133}$\\textrm{Sn} are presented.

  3. Coulomb Excitation with CARIBU Beams: Octupole Strength in 144Ba Measured with GRETINA and CHICO2

    NASA Astrophysics Data System (ADS)

    Bucher, Brian; Zhu, Shaofei; ANL, LBNL, LLNL, Rochester, Florida St, Liverpool, Maryland, Notre Dame, Ohio,; W. Scotland Collaboration

    2014-09-01

    The neutron-rich barium isotopes sit in one of the few mass regions on the nuclear chart observed to display octupole correlations. These isotopes are challenging to study since they lie far from stability and are thus difficult to produce in large quantities. In particular, this region is interesting for studying the evolution of octupole correlations since the enhancement of the E1 strength drops by an order of magnitude from 144Ba to 146Ba, where shell corrections appear to play a significant role. To provide unambiguous insight into the octupole correlations, B(E3) strengths have been measured using Coulomb excitation of 144Ba beams at 650 MeV on a 1 mg/cm2 208Pb target. This experiment represents the first successful measurement utilizing re-accelerated CARIBU beams combined with the γ-ray tracking array GRETINA and the auxiliary charged-particle detector CHICO2. Preliminary results from the experiment will be presented. The neutron-rich barium isotopes sit in one of the few mass regions on the nuclear chart observed to display octupole correlations. These isotopes are challenging to study since they lie far from stability and are thus difficult to produce in large quantities. In particular, this region is interesting for studying the evolution of octupole correlations since the enhancement of the E1 strength drops by an order of magnitude from 144Ba to 146Ba, where shell corrections appear to play a significant role. To provide unambiguous insight into the octupole correlations, B(E3) strengths have been measured using Coulomb excitation of 144Ba beams at 650 MeV on a 1 mg/cm2 208Pb target. This experiment represents the first successful measurement utilizing re-accelerated CARIBU beams combined with the γ-ray tracking array GRETINA and the auxiliary charged-particle detector CHICO2. Preliminary results from the experiment will be presented. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH

  4. Magnetic moment and lifetime measurements of Coulomb-excited states in Cd106

    DOE PAGESBeta

    Benczer-Koller, N.; Kumbartzki, G. J.; Speidel, K. -H.; Torres, D. A.; Robinson, S. J. Q.; Sharon, Y. Y.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; et al

    2016-09-06

    The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in 106Cd. Methods: In an inverse kinematics reaction, a 106Cd beam impinging on a 12C target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for 106Cd. As a result, the g factorsmore » of the 2+1 and 4+1 states in 106Cd were measured to be g(2+1) = +0.398(22) and g(4+1) = +0.23(5). A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ(106Cd; 2+1) = 7.0(3) ps and τ(106Cd; 4+1) = 2.5(2) ps. The mean life τ(106Cd; 2+2) = 0.28(2) ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ(106Cd; 4+3) = 1.1(1) ps and τ(106Cd; 3–1) = 0.16(1) ps were determined for the first time. In conclusion, the newly measured g(4+1) of 106Cd is found to be only 59% of the g(2+1). This difference cannot be explained by either shell-model or collective-model calculations.« less

  5. Mixing of Triaxial and Intruder Configurations in 72,76Ge Studied via Multistep Coulomb Excitation

    NASA Astrophysics Data System (ADS)

    Ayangeakaa, A. D.; Janssens, R. V. F.; Anl Collaboration; Llnl Collaboration; Lbnl Collaboration; U. Of Maryland Collaboration; Csnsm Collaboration

    2015-10-01

    The low-lying states in even-even Ge isotopes have been a subject of intense scrutiny for many years due to the inherent challenge of interpreting their low-energy structure. While several explanations such as vibrational-rotational coupling, 2p-2h intruder mixing and shape coexistence have been proposed, none have been able to satisfactorily reproduce the properties of these low-lying excitations. Recent theoretical calculations have, however, emphasized the importance of the triaxial degree of freedom and, indeed, 76Ge is proposed to exhibit static triaxiality. In this study, the electromagnetic properties of low-lying states in 72,76Ge were investigated via sub-barrier multiple Coulomb excitation with GRETINA and CHICO-2. In the case of 72Ge, the extracted matrix elements seem to agree with the shape coexistence interpretation between the 01+ and 02+ states. However, significant mixing between the wavefunctions of these two states and triaxiality are required to reproduce the overall data. These results and calculations based on a triaxial rotor model with configuration mixing will be presented, and the role of triaxiality will be discussed. Preliminary results for 76Ge will also be highlighted. This work is supported by the DOE, Office of Science, Office of Nuclear Physics under Contract Number DE-AC02-06CH11357, and Grant No. DE-FG02-94ER40834 and DE-FG02-08ER41556.

  6. Coulombic Effects on Excited States in a Small Quantum Dot

    NASA Astrophysics Data System (ADS)

    Goldhaber-Gordon, David; Duncan, David; Westervelt, R. M.; Maranowski, K. M.; Gossard, A. C.

    2000-03-01

    The excitation spectrum of a quantum dot varies with the addition of electrons, as successive single-particle eigenstates become filled in the ground state and so cannot accomodate additional electrons. Previous experiments have observed that each spatial state becomes unavailable for transport of further electrons after only one electron has occupied it. We have investigated state occupancy in the excitation spectrum of a small (200 nm X 200 nm) quantum dot laterally defined by capacitively coupled gate electrodes in a GaAs/AlGaAs heterostructure. For our dots, quantized level spacing Δ E ≈ 300 μeV and charging energy Ec ≈ 2 meV. We have studied the evolution of features in the excitation spectrum with magnetic field and equilibrium occupancy and have identified the pattern of spins for the added electrons. These results test the applicability of the spin-degenerate constant interaction picture as well as its limitations.

  7. Testing refined shell-model interactions in the s d shell: Coulomb excitation of 26Na

    NASA Astrophysics Data System (ADS)

    Siebeck, B.; Seidlitz, M.; Blazhev, A.; Reiter, P.; Altenkirch, R.; Bauer, C.; Butler, P. A.; de Witte, H.; Elseviers, J.; Gaffney, L. P.; Hess, H.; Huyse, M.; Kröll, T.; Lutter, R.; Pakarinen, J.; Pietralla, N.; Radeck, F.; Scheck, M.; Schneiders, D.; Sotty, C.; van Duppen, P.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Miniball Collaboration; Rex-Isolde Collaboration

    2015-01-01

    Background: Shell-model calculations crucially depend on the residual interaction used to approximate the nucleon-nucleon interaction. Recent improvements to the empirical universal s d interaction (USD) describing nuclei within the s d shell yielded two new interactions—USDA and USDB—causing changes in the theoretical description of these nuclei. Purpose: Transition matrix elements between excited states provide an excellent probe to examine the underlying shell structure. These observables provide a stringent test for the newly derived interactions. The nucleus 26Na with 7 valence neutrons and 3 valence protons outside the doubly-magic 16O core is used as a test case. Method: A radioactive beam experiment with 26Na (T1 /2=1 ,07 s ) was performed at the REX-ISOLDE facility (CERN) using Coulomb excitation at safe energies below the Coulomb barrier. Scattered particles were detected with an annular Si detector in coincidence with γ rays observed by the segmented MINIBALL array. Coulomb excitation cross sections of the beam have been obtained by normalization to the well known Coulomb excitation cross sections of the 104Pd target. Results: The observation of three γ -ray transitions in 26Na together with available spectroscopic data allows us to determine E 2 - and M 1 -transitional matrix elements. Results are compared to theoretical predictions. Conclusion: The improved theoretical description of 26Na could be validated. Remaining discrepancies between experimental data and theoretical predictions indicate the need for future experiments and possibly further theoretical improvements.

  8. Coulomb deexcitation of muonic hydrogen in collisions with atoms of hydrogen isotopes

    SciTech Connect

    Kravtsov, A.V.; Mikhailov, A.I.

    1995-05-01

    The asymptotic theory of nonadiabatic transitions is used to treat Coulomb deexcitation of muonic hydrogen in hydrogen, including the effect of electron shielding of the charge of the target nucleus. The rates are calculated for an isotopically pure target and for a mixture of hydrogen isotopes. For a mixture of isotopes the rates of direct and inverse charge exchange with deexcitation are also calculated. 13 refs., 3 figs., 6 tabs.

  9. Electron-pair excitations and the molecular Coulomb continuum

    SciTech Connect

    Colgan, James

    2009-01-01

    Electron-pair excitations in the molecular hydrogen continuum are described by quantizing rotations of the momentum plane of the electron pair about by the pair's relative momentum. A helium-like description of the molecular pi.Joto double ionization is thus extended to higher angular momenta of the electron pair. A simple three-state superposition is found to account surprisingly well for recent observations of noncoplanar electron-pair, molecular-axis angular distributions.

  10. Dynamical coupling of pygmy and giant resonances in relativistic Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Brady, N. S.; Aumann, T.; Bertulani, C. A.; Thomas, J. O.

    2016-06-01

    We study the Coulomb excitation of pygmy dipole resonances (PDR) in heavy ion reactions at 100 MeV/nucleon and above. The reactions 68Ni +197Au and 68Ni +208Pb are taken as practical examples. Our goal is to address the question of the influence of giant resonances on the PDR as the dynamics of the collision evolves. We show that the coupling to the giant resonances affects considerably the excitation probabilities of the PDR, a result that indicates the need of an improved theoretical treatment of the reaction dynamics at these bombarding energies.

  11. Coulomb excitation of the proton-dripline nucleus {sup 20}Na

    SciTech Connect

    Schumaker, M. A.; Svensson, C. E.; Bandyopadhyay, D.; Demand, G. A.; Finlay, P.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Wong, J.; Cline, D.; Hayes, A. B.; Whitbeck, A.; Hackman, G.; Pearson, C. J.; Andreyev, A.; Ball, G. C.; Buchmann, L.; Churchman, R.

    2009-10-15

    The low-energy structure of the proton dripline nucleus {sup 20}Na has been studied using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. A 1.7-MeV/nucleon {sup 20}Na beam of {approx}5x10{sup 6} ions/s was Coulomb excited by a 0.5-mg/cm{sup 2nat}Ti target. Scattered beam and target particles were detected by the BAMBINO segmented Si detector while {gamma} rays were detected by two TIGRESS HPGe clover detectors set perpendicular to the beam axis. Coulomb excitation from the 2{sup +} ground state to the first excited 3{sup +} and 4{sup +} states was observed, and B({lambda}L) values were determined using the 2{sup +}{yields}0{sup +} de-excitation in {sup 48}Ti as a reference. The resulting B({lambda}L){down_arrow} values are B(E2;3{sup +}{yields}2{sup +})=55{+-}6 e{sup 2} fm{sup 4} (17.0{+-}1.9 W.u.), B(E2;4{sup +}{yields}2{sup +})=35.7{+-}5.7 e{sup 2} fm{sup 4} (11.1{+-}1.8 W.u.), and B(M1;4{sup +}{yields}3{sup +})=0.154{+-}0.030 {mu}{sub N}{sup 2} (0.086{+-}0.017 W.u.). These measurements provide the first experimental determination of B({lambda}L) values for this proton dripline nucleus of astrophysical interest.

  12. Structure of low-lying states in 140Sm studied by Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Klintefjord, M.; Hadyńska-KlÈ©k, K.; Görgen, A.; Bauer, C.; Bello Garrote, F. L.; Bönig, S.; Bounthong, B.; Damyanova, A.; Delaroche, J.-P.; Fedosseev, V.; Fink, D. A.; Giacoppo, F.; Girod, M.; Hoff, P.; Imai, N.; Korten, W.; Larsen, A.-C.; Libert, J.; Lutter, R.; Marsh, B. A.; Molkanov, P. L.; Naïdja, H.; Napiorkowski, P.; Nowacki, F.; Pakarinen, J.; Rapisarda, E.; Reiter, P.; Renstrøm, T.; Rothe, S.; Seliverstov, M. D.; Siebeck, B.; Siem, S.; Srebrny, J.; Stora, T.; Thöle, P.; Tornyi, T. G.; Tveten, G. M.; Van Duppen, P.; Vermeulen, M. J.; Voulot, D.; Warr, N.; Wenander, F.; De Witte, H.; Zielińska, M.

    2016-05-01

    The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 21+ state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that 140Sm shows considerable γ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivity in this mass region.

  13. B(E1) Strengths from Coulomb excitation of 11Be

    SciTech Connect

    Summers, N C; Pain, S D; Orr, N A; Catford, W N; Angelique, J C; Ashwood, N I; Bouchat, V; Clarke, N M; Curtis, N; Freer, M; Fulton, B R; Hanappe, F; Labiche, M; Loucey, J L; Lemmon, R C; Mahboub, D; Ninane, A; Normand, G; Nunes, F M; Soic, N; Stuttge, L; Timis, C N; Thompson, I; Winfield, J S; Ziman, V

    2007-03-06

    The B(E1;1/2{sup +}{yields} 1/2{sup -}) strength for {sup 11}Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the excitation cross section for {sup 11}Be+{sup 208}Pb at 38.6 MeV/nucleon is reported. The B(E1) strength of 0.105(12) e{sup 2}fm{sup 2} derived from this measurement is consistent with those made previously at 60 and 64 MeV/nucleon, in contrast to an anomalously low result obtained at 43 MeV/nucleon. By coupling a multi-configuration description of the projectile structure with realistic reaction theory, the XCDCC model provides for the first time a fully quantum mechanical description of Coulomb excitation. The XCDCC calculations reveal that the excitation process involves significant contributions from nuclear, continuum, and higher-order effects. An analysis of the present and two earlier intermediate energy measurements yields a combined B(E1) strength of 0.105(7) e{sup 2}fm{sup 2}. This value is in good agreement with the value deduced independently from the lifetime of the 1/2{sup -} state in {sup 11}Be, and has a comparable precision.

  14. X-ray production with heavy post-accelerated radioactive-ion beams in the lead region of interest for Coulomb-excitation measurements

    NASA Astrophysics Data System (ADS)

    Bree, N.; Wrzosek-Lipska, K.; Butler, P. A.; Gaffney, L. P.; Grahn, T.; Huyse, M.; Kesteloot, N.; Pakarinen, J.; Petts, A.; Van Duppen, P.; Warr, N.

    2015-10-01

    Characteristic K X-rays have been observed in Coulomb-excitation experiments with heavy radioactive-ion beams in the lead region (Z = 82), produced at the REX-ISOLDE facility, and were used to identify the decay of strongly converted transitions as well as monopole 02+ → 01+ transitions. Different targets were used, and the X-rays were detected by the Miniball γ-ray spectrometer surrounding the target position. A stable mercury isotope, as well as neutron-deficient mercury, lead, polonium, and radon isotopes were studied, and a detailed description of the analysis using the radioactive 182,184,186,188Hg isotopes is presented. Apart from strongly converted transitions originating from the decay of excited states, the heavy-ion induced K-vacancy creation process has been identified as an extra source for K X-ray production. Isolating the atomic component of the observed K X-rays is essential for a correct analysis of the Coulomb-excitation experiment. Cross sections for the atomic reaction have been estimated and are compared to a theoretical approach.

  15. Do nuclei go pear-shaped? Coulomb excitation of 220Rn and 224Ra at REX-ISOLDE (CERN)

    NASA Astrophysics Data System (ADS)

    Scheck, M.; Gaffney, L. P.; Butler, P. A.; Hayes, A. B.; Wenander, F.; Albers, M.; Bastin, B.; Bauer, C.; Blazhev, A.; Boenig, S.; Bree, N.; Cederkall, J.; Chupp, T.; Cline, D.; Cocolios, T. E.; Davinson, T.; De Witte, H.; Diriken, J.; Grahn, T.; Herzan, A.; Huyse, M.; Jenkins, D. G.; Joss, D. T.; Kesteloot, N.; Konki, J.; Kowalczyk, M.; Kroell, Th.; Kwan, E.; Lutter, R.; Moschner, K.; Napiorkowski, P.; Pakarinen, J.; Pfeiffer, M.; Radeck, D.; Reiter, P.; Reynders, K.; Rigby, S. V.; Robledo, L. M.; Rudigier, M.; Sambi, S.; Seidlitz, M.; Siebeck, B.; Stora, T.; Thoele, P.; Van Duppen, P.; Vermeulen, M. J.; von Schmid, M.; Voulot, D.; Warr, N.; Wimmer, K.; Wrzosek-Lipska, K.; Wu, C. Y.; Zielinska, M.

    2015-05-01

    The IS475 collaboration conducted Coulomb-excitation experiments with post-accelerated radioactive 220Rn and 224Ra beams at the REX-ISOLDE facility. The beam particles (Ebeam: 2.83 MeV/u) were Coulomb excited using 60Ni, 114Cd, and 120Sn scattering targets. De-excitation γ-rays were detected employing the Miniball array and scattered particles were detected in a silicon detector. Exploiting the Coulomb-excitation code GOSIA for each nucleus several matrix elements could be obtained from the measured γ-ray yields. The extracted ‹3-||E3||0+› matrix element allows for the conclusion that, while 220Rn represents an octupole vibrational system, 224Ra has already substantial octupole correlations in its ground state. This finding has implications for the search of CP-violating Schiff moments in the atomic systems of the adjacent odd-mass nuclei.

  16. Coulomb excitation of radioactive {sup 21}Na and its stable mirror {sup 21}Ne

    SciTech Connect

    Schumaker, M. A.; Svensson, C. E.; Demand, G. A.; Finlay, P.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Wong, J.; Cline, D.; Hayes, A. B.; Whitbeck, A.; Hackman, G.; Morton, A. C.; Pearson, C. J.; Andreyev, A.; Ball, G. C.; Buchmann, L.; Churchman, R.

    2008-10-15

    The low-energy structures of the mirror nuclei {sup 21}Ne and radioactive {sup 21}Na have been examined by using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of {approx}5x10{sup 6} ions/s were accelerated to 1.7 MeV/A and Coulomb excited in a 0.5 mg/cm{sup 2} {sup nat}Ti target. Scattered beam and target particles were detected by the segmented Si detector BAMBINO, while {gamma} rays were observed by using two TIGRESS HPGe clover detectors perpendicular to the beam axis. For each isobar, Coulomb excitation from the (3/2){sup +} ground state to the first excited (5/2){sup +} state was observed and B(E2) values were determined by using the 2{sup +}{yields}0{sup +} de-excitation in {sup 48}Ti as a reference. The {phi} segmentation of BAMBINO was used to deduce tentative assignments for the signs of the mixing ratios between the E2 and M1 components of the transitions. The resulting B(E2){up_arrow} values are 131{+-}9 e{sup 2} fm{sup 4} (25.4{+-}1.7 W.u.) for {sup 21}Ne and 205{+-}14 e{sup 2} fm{sup 4} (39.7{+-}2.7 W.u.) for {sup 21}Na. The fit to the present data and the known lifetimes determined E2/M1 mixing ratios and B(M1){down_arrow} values of {delta}=(-)0.0767{+-}0.0027 and 0.1274{+-}0.0025 {mu}{sub N}{sup 2} and {delta}=(+)0.0832{+-}0.0028 and 0.1513{+-}0.0017 {mu}{sub N}{sup 2} for {sup 21}Ne and {sup 21}Na, respectively (with Krane and Steffen sign convention). By using the effective charges e{sub p}=1.5e and e{sub n}=0.5e, the B(E2) values produced by the p-sd shell model are 30.7 and 36.4 W.u. for {sup 21}Ne and {sup 21}Na, respectively. This analysis resolves a significant discrepancy between a previous experimental result for {sup 21}Na and shell-model calculations.

  17. Analysis methods of safe Coulomb-excitation experiments with radioactive ion beams using the GOSIA code

    NASA Astrophysics Data System (ADS)

    Zielińska, M.; Gaffney, L. P.; Wrzosek-Lipska, K.; Clément, E.; Grahn, T.; Kesteloot, N.; Napiorkowski, P.; Pakarinen, J.; Van Duppen, P.; Warr, N.

    2016-04-01

    With the recent advances in radioactive ion beam technology, Coulomb excitation at safe energies becomes an important experimental tool in nuclear-structure physics. The usefulness of the technique to extract key information on the electromagnetic properties of nuclei has been demonstrated since the 1960s with stable beam and target combinations. New challenges present themselves when studying exotic nuclei with this technique, including dealing with low statistics or number of data points, absolute and relative normalisation of the measured cross-sections and a lack of complementary experimental data, such as excited-state lifetimes and branching ratios. This paper addresses some of these common issues and presents analysis techniques to extract transition strengths and quadrupole moments utilising the least-squares fit code, GOSIA.

  18. Relativistic Coulomb excitation within the time dependent superfluid local density approximation

    SciTech Connect

    Stetcu, I.; Bertulani, C. A.; Bulgac, A.; Magierski, P.; Roche, K. J.

    2015-01-06

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus 238U. The approach is based on the superfluid local density approximation formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We compute the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance, and giant quadrupole modes are excited during the process. As a result, the one-body dissipation of collective dipole modes is shown to lead a damping width Γ↓≈0.4 MeV and the number of preequilibrium neutrons emitted has been quantified.

  19. Doubly excited {sup 1,3}P{sup e} resonance states of helium and the hydrogen negative ion interacting with Coulomb and screened Coulomb potentials

    SciTech Connect

    Kar, Sabyasachi; Ho, Y. K.

    2011-04-15

    We have investigated the doubly excited {sup 1,3}P{sup e} resonance states of helium and the hydrogen negative ion interacting with Coulomb and screened Coulomb potentials using exponential correlated wave functions. In the pure Coulomb case, calculations have been carried out by using the complex-coordinate rotation and the stabilization method. The {sup 1}P{sup e} resonance states of He below the N= 3, 4, and 5 thresholds of He{sup +}, and the {sup 3}P{sup e} resonance states of He below the N= 3 thresholds of He{sup +}, are reported. The 5p{sup 2} {sup 3}P{sup e} state, which has attracted recent interest, is also reported and discussed. In the screened Coulomb case, we have used the stabilization method to obtain two different series (3pnp and 3dnd) of resonance states below the N= 3 He{sup +} threshold as a function of the screening parameters. Resonance widths for the 3dnd series show some interesting behaviors. The resonance parameters (position and width) for helium and the hydrogen negation ion as functions of the screening parameters are reported.

  20. In-depth analysis of Coulomb Volkov approaches to ionization and excitation by laser pulses

    NASA Astrophysics Data System (ADS)

    R, Guichard; H, Bachau; E, Cormier; R, Gayet; D, Rodriguez V.

    2007-10-01

    In perturbation conditions, above-threshold ionization spectra produced in the interaction of atoms with femtosecond short-wavelength laser pulses are well predicted by a theoretical approach called CV2-, which is based on Coulomb-Volkov-type states. However, when resonant intermediate states play a significant role in a multiphoton transition, the CV2- transition amplitude does not take their influence into account. In a previous paper, this influence has been introduced separately as a series of additional sequential processes interfering with the direct process. To give more credit to this procedure, called modified CV2- (MCV2-), a perturbation expansion of the standard CV2- transition amplitude is compared here to the standard time-dependent perturbation series and the strong field approximation. It is shown that the CV2- transition amplitude consists merely in a simultaneous absorption of all photons involved in the transition, thus avoiding all intermediate resonant state influence. The present analysis supports the MCV2- procedure that consists in introducing explicitly the other quantum paths, which contribute significantly to ionization, such as passing through intermediate resonances. Further, this analysis permits to show that multiphoton excitation may be addressed by a Coulomb-Volkov approach akin to MCV2-.

  1. Investigating shape evolution and the emergence of collectivity through the synergy of Coulomb excitation and beta decay

    SciTech Connect

    Allmond, James M

    2016-01-01

    The synthesis of Coulomb excitation and decay offers very practical advantages in the study of nuclear shapes and collectivity. For instance, Coulomb excitation is unique in its ability to measure the electric quadrupole moments, i.e., I2 ||M(E2)||I1 matrix elements, of excited, non-isomeric states in atomic nuclei, providing information on the intrinsic shape. However, the Coulomb excitation analysis and structural inter- pretation can be strongly dependent upon weak transitions or decay branches, which are often obscured by the Compton background. Transitions of particular interest are those low in energy and weak in intensity due to the E 5 attenuation factor. These weak decay branches can often be determined with high precision from -decay studies. Recently, 106Mo and 110Cd were studied by both Coulomb excitation and decay. Preliminary results of new weak decay branches following decay of 110mAg to 110Cd are presented; these results will challenge competing interpretations based on vibrations and configuration mixing.

  2. Relativistic Coulomb excitation within the time dependent superfluid local density approximation

    DOE PAGESBeta

    Stetcu, I.; Bertulani, C. A.; Bulgac, A.; Magierski, P.; Roche, K. J.

    2015-01-06

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus 238U. The approach is based on the superfluid local density approximation formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We compute the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, themore » dipole pygmy resonance, and giant quadrupole modes are excited during the process. As a result, the one-body dissipation of collective dipole modes is shown to lead a damping width Γ↓≈0.4 MeV and the number of preequilibrium neutrons emitted has been quantified.« less

  3. Interatomic Coulombic decay following resonant core excitation of Ar in argon dimer

    SciTech Connect

    Miteva, T.; Chiang, Y.-C.; Kuleff, A. I.; Gokhberg, K. Cederbaum, L. S.; Kolorenč, P.

    2014-08-14

    A scheme utilizing excitation of core electrons followed by the resonant-Auger – interatomic Coulombic decay (RA-ICD) cascade was recently proposed as a means of controlling the generation site and energies of slow ICD electrons. This control mechanism was verified in a series of experiments in rare gas dimers. In this article, we present fully ab initio computed ICD electron and kinetic energy release spectra produced following 2p{sub 3/2} → 4s, 2p{sub 1/2} → 4s, and 2p{sub 3/2} → 3d core excitations of Ar in Ar{sub 2}. We demonstrate that the manifold of ICD states populated in the resonant Auger process comprises two groups. One consists of lower energy ionization satellites characterized by fast interatomic decay, while the other consists of slow decaying higher energy ionization satellites. We show that accurate description of nuclear dynamics in the latter ICD states is crucial for obtaining theoretical electron and kinetic energy release spectra in good agreement with the experiment.

  4. Octupole deformation in 144,146Ba measured by Coulomb excitation of radioactive beams

    NASA Astrophysics Data System (ADS)

    Bucher, Brian; Zhu, Shaofei; ANL, LBNL, LLNL, Rochester, Florida State, Liverpool, Maryland, Notre Dame, Ohio, W. Scotland Collaboration

    2015-10-01

    The exotic, neutron-rich 144Ba (t1 / 2 = 11.5 s) and 146Ba (t1 / 2 = 2.2 s) nuclei are expected to exhibit some of the strongest octupole correlations in A < 200 systems. Up to now, evidence for such strong octupole correlations has been inferred from observations of low-lying negative-parity states and from the interleaving of positive- and negative-parity levels in the ground-state band. However, the E1 transition strengths are very different in these two nuclei, with two orders of magnitude reduction in 146Ba. In this experiment, we measure the octupole strength directly by Coulomb excitation of post-accelerated 144,146Ba beams produced at CARIBU using CHICO2 and GRETINA. In 144Ba, we found B(E3;3 -->0) = 48(-34+ 25) W.u., a value considerably larger than theoretical predictions, while preliminary results for 146Ba are also indicative of strong octupole collectivity. The experimental conditions, the analysis, and the results from these challenging new measurements will be presented. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DOE DE-AC52-07NA27344 (LLNL), and NSF.

  5. Role of Coulomb repulsion in correlated-electron emission from a doubly excited state in nonsequential double ionization of molecules

    NASA Astrophysics Data System (ADS)

    Huang, Cheng; Guo, Wenliang; Zhou, Yueming; Wu, Zhengmao

    2016-01-01

    With the classical ensemble model, we investigate nonsequential double ionization of aligned molecules by few-cycle laser pulses at low intensity, where the two electrons finally are ionized through a transition doubly excited state induced by recollision. The correlated electron momentum distribution of parallel molecules exhibits the line-shaped structure parallel to the diagonal. Our analysis indicates that besides the ionization time difference of two electrons from the doubly excited state, the final-state e-e Coulomb repulsion plays a vital role in the formation of the line-shaped structural momentum distribution. For perpendicular molecules, due to the prominent near half-cycle ionization time difference between the two electrons from the doubly excited state, the momentum distribution shows clear anticorrelation behavior.

  6. Complex-Scaling Treatment for Doubly Excited Inter-Shell Resonances in H- Interacting with Screened Coulomb (Yukawa) Potentials

    NASA Astrophysics Data System (ADS)

    Ho, Y. K.; Kar, S.

    2012-10-01

    The doubly-excited inter-shell resonance states of the hydrogen negative ion with screened Coulomb potentials are investigated in the framework of complex-scaling method. Highly correlated wave functions with terms up to 1078 in Hylleraas coordinates are used. The resonance parameters for the 2 s3 s 1 S e associated with the H ( N = 2) threshold and the 3 s4 s 1 S e state associated with the H ( N = 3) threshold for various screening strengths are reported. Comparisons are made with other available data in the literature.

  7. Coulomb excitation of a {sup 242}Am isomeric target : E2, E3 strengths, rotational alignment, and collective enhancement.

    SciTech Connect

    Hayes, A. B.; Cline, D.; Moody, K. J.; Ragnarsson, I.; Wu, C. Y.; Becker, J. A.; Carpenter, M. P.; Carroll, J. J.; Gohlke, D.; Greene, J. P.; Hecht, A. A.; Janssens, R. V. F.; Karamian, S. A.; Lauritsen, T.; Lister, C. J.; Macri, R. A.; Propri, R.; Seweryniak, D.; Wang, X.; Wheeler, R.; Zhu, S.

    2010-10-29

    A 98% pure {sup 242m}Am (K=5{sup -}, t{sub 1/2} = 141 years) isomeric target was Coulomb excited with a 170.5-MeV {sup 40}Ar beam. The selectivity of Coulomb excitation, coupled with the sensitivity of Gammasphere plus CHICO, was sufficient to identify 46 new states up to spin 18 {h_bar} in at least four rotational bands; 11 of these new states lie in the isomer band, 13 in a previously unknown yrast K{sup {pi}} = 6{sup -} rotational band, and 13 in a band tentatively identified as the predicted yrast K{sup {pi}} = 5{sup +} band. The rotational bands based on the K{sup {pi}} = 5{sup -} isomer and the 6{sup -} bandhead were populated by Coulomb excitation with unexpectedly equal cross sections. The {gamma}-ray yields are reproduced by Coulomb excitation calculations using a two-particle plus rotor model (PRM), implying nearly complete {Delta}K = 1 mixing of the two almost-degenerate rotational bands, but recovering the Alaga rule for the unperturbed states. The degeneracy of the 5{sup -} and 6{sup -} bands allows for precise determination of the mixing interaction strength V, which approaches the strong-mixing limit; this agrees with the 50% attenuation of the Coriolis matrix element assumed in the model calculations. The fractional admixture of the I{sub K}{sup {pi}} = 6{sub 6{sup -}} state in the nominal 6{sub 5{sup -}} isomer band state is measured within the PRM as 45.6{sub -1.1}{sup +0.3}%. The E2 and M1 strengths coupling the 5{sup -} and 6{sup -} bands are enhanced significantly by the mixing, while E1 and E2 couplings to other low-K bands are not measurably enhanced. The yields of the 5{sup +} band are reproduced by an E3 strength of {approx}15 W.u., competitive with the interband E2 strength. Alignments of the identified two-particle Nilsson states in {sup 242}Am are compared with the single-particle alignments in {sup 241}Am.

  8. Shape vibration and quasiparticle excitations in the lowest 0+ excited state in erbium isotopes

    NASA Astrophysics Data System (ADS)

    Chen, Fang-Qi; Egido, J. Luis

    2016-06-01

    The ground and first excited 0+ states of the -172Er156 isotopes are analyzed in the framework of the generator coordinate method. The shape parameter β is used to generate wave functions with different deformations which together with the two-quasiparticle states built on them provide a set of states. An angular momentum and particle number projection of the latter spawn the basis states of the generator coordinate method. With this ansatz and using the separable pairing plus quadrupole interaction we obtain a good agreement with the experimental spectra and E 2 transition rates up to moderate spin values. The structure of the wave functions suggests that the first excited 0+ states in the soft Er isotopes are dominated by shape fluctuations, while in the well deformed Er isotopes the two-quasiparticle states are more relevant. In between, both degrees of freedom are necessary.

  9. Electron-hydrogen-atom elastic and inelastic scattering with screened Coulomb interaction around the n=2 excitation threshold

    SciTech Connect

    Zhang Songbin; Wang Jianguo; Janev, R. K.

    2010-03-15

    The effects of Coulomb interaction screening on electron-hydrogen-atom elastic and excitation scattering around the n=2 threshold have been investigated by using the R-matrix method with pseudostates. The elastic and excitation collision strengths show dramatic changes when the interaction screening length D varies from {infinity} to 3.8 a.u., as a result of the convergence of {sup 1,3}S Feshbach resonances to the varying 2s threshold and of the transformation of {sup 1,3}P and {sup 1}D Feshbach resonances into shape-type resonances when they pass across the 2s and 2p threshold at certain critical value of D, respectively [S. B. Zhang et al., Phys. Rev. Lett. 104, 023203 (2010)]. The resonance parameters for a large number of D in the range D={infinity}-3.8 a.u. are presented. It is observed that the {sup 1,3}P and {sup 1}D resonance contributions to the elastic and excitation collision strengths decrease rapidly with decreasing D after the resonance passes the critical D value. The contribution of a {sup 1}S{sup e} Feshbach resonance to the elastic or excitation collision strength changes into a cusp after the resonance merges into its parent 2s state and immerses into the background with the further decrease of D.

  10. High-precision B (E2) measurements of semi-magic Ni58,60,62,64 by Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Allmond, J. M.; Brown, B. A.; Stuchbery, A. E.; Galindo-Uribarri, A.; Padilla-Rodal, E.; Radford, D. C.; Batchelder, J. C.; Howard, M. E.; Liang, J. F.; Manning, B.; Varner, R. L.; Yu, C.-H.

    2014-09-01

    High-precision reduced electric-quadrupole transition probabilities B (E2;01+→21+) have been measured from single-step Coulomb excitation of semi-magic Ni58,60,62,64 (Z=28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the nickel beams through the carbon target were directly measured with a zero-degree Bragg detector and the absolute B (E2) values were normalized by Rutherford scattering. The B (E2) values disagree with recent lifetime studies that employed the Doppler-shift attenuation method. The present high-precision B (E2) values reveal an asymmetry about Ni62, midshell between N =28 and 40, with larger values towards Ni56 (Z =N=28). The experimental B (E2) values are compared with shell-model calculations in the full pf model space and the results indicate a soft Ni56 core.

  11. 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.

  12. Atomic Regime in Which the Magnetic Interaction Dominates the Coulomb Interaction for Highly Excited States of Hydrogen

    PubMed Central

    Mueller, Ronald O.; Hughes, Vernon W.

    1974-01-01

    The atomic regime in which the interaction of the electron with an external magnetic field dominates the Coulomb interaction with the nucleus, relevant to pulsars, can be realized at laboratory magnetic fields for discrete autoionized states of hydrogen, at energies above the ionization limit. Approximate wave functions, energy levels, and electric dipole transition probabilities are presented for hydrogen, and an atomic beam absorption spectroscopy experiment at 50 kG is proposed to study this new regime. PMID:16578723

  13. High-precision B(E2) measurements of semi-magic 58,60,62,64Ni by Coulomb excitation

    SciTech Connect

    Allmond, James M; Brown, Alex; Stuchbery, Andrew E; Galindo-Uribarri, Alfredo {nmn}; Padilla-Rodal, Elizabeth; Radford, David C; Batchelder, J. C.; Howard, Meredith E; Liang, J Felix; Manning, Brett M; Varner Jr, Robert L; Yu, Chang-Hong

    2014-01-01

    High-precision reduced electric-quadrupole transition probabilities B(E2) have been measured from single-step Coulomb excitation of semi-magic 58,60,62,64 Ni (Z = 28) beams at 1.8 MeV per nucleon on a natural carbon target. The energy loss of the nickel beams through the carbon target were directly measured with a zero-degree Bragg detector and the absolute B(E2) values were normalized by Rutherford scattering. The B(E2) values disagree with recent lifetime studies that employed the Doppler-shift attenuation method. The present high-precision B(E2) values reveal an asymmetry about 62 Ni, midshell between N = 28 and 40, with larger values towards 56 Ni (Z = N = 28). The experimental B(E2) values are compared with shell-model calculations in the full pf model space and the results indicate a soft 56 Ni core.

  14. Systematic study of excited 0+ states in the Er isotopes populated in the (p , t) reaction

    NASA Astrophysics Data System (ADS)

    Garrett, P. E.; Finlay, A.; Kisliuk, D.; Chagnon-Lessard, S.; Diaz Varela, A.; Dunlop, R.; Jamieson, D. S.; Leach, K. G.; Svensson, C. E.; Ball, G. C.; Triambak, S.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

    2014-09-01

    The nature of excited 0+ states in well-deformed nuclei continue to pose a challenge in nuclear structure. Often, even the nature of the first excited 0+ state, 02+, is unclear and interpretations involving β vibrations, pairing excitations, two-phonon γ vibrations, etc., have been advanced with different degrees of success. A major issue historically has been lack of data on excited 0+ states. In light of this, the study of the Er isotopes has been extended via the 162Er and 164Er (p , t) reactions. The experiments were performed at the Maier-Leibnitz Laboratory using 22 MeV proton beams on highly-enriched targets of 162,164Er, and the reaction products were analyzed with the Q3D spectrograph. Strong populations of the 02+ states have been observed. The systematics of the strong population of the 0+ states in the Er (p , t) reactions sheds light on the underlying nature of these levels.

  15. The End of Superdeformation: De-excitation to Spherical States in Lead Isotopes

    NASA Astrophysics Data System (ADS)

    Cizewski, Jolie A.

    1997-04-01

    Numerous examples of superdeformed rotational bands at high angular momenta have been observed in medium and heavy mass nuclei. The A ~190 region has been especially rich - superdeformed (SD) excitations have been identified in at least 22 isotopes and a large fraction of these bands have γ-ray energies which are simply related. However, the fundamental properties of excitation energy and spin-parity have only recently between determined. The first candidate for a discrete transition which links the SD band to ``normal" deformed (ND) excitations was observed in ^194Pb.(M. J. Brinkman, et al., Phys. Rev. C53), R1461 (1996). Subsequently, many transitions which connect SD and ND excitations in ^194Hg were observed, which allowed the determination of the excitation energy and spin.footnote T. L. Khoo, et al., Phys. Rev. Lett. 76, 1583 (1996). In ^194Pb as many as 12 discrete transitionsfootnote A. Lopez-Martens, et al., Phys. Lett. B380, 18 (1996) and K. Hauschild, et al., Phys. Rev. C (1996). have now been identified with the Eurogam or Gammasphere arrays of γ-ray detectors. This has allowed model-independent determinations of the excitation energy, spin, and parity of these states. The decay of the SD to ND states has been suggested to proceed via mixing between SD and ND excitations with similar excitation energies and angular momenta,(E. Vigezzi, et al., Phys. Lett. B249), 163 (1990). and allows a probe of the complex character of excitations at moderate temperatures in the ND well. In addition, the quasi-continuous spectrum of transitions which link SD and ND excitations can be used to probe level density and pairing degrees of freedom in hot, ND nuclei.footnote T. Dossing, et al., Phys. Rev. Lett. 75, 1276 (1995); A. Lopez-Martens, et al., PRL 77, 1707 (1996); and D.P. McNabb, et al., BAPS 41, 1237 (1996). Studies of the deexcitation of SD bands will be reviewed with a focus on the Pb isotopes.

  16. 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.

  17. Experimental reconstruction of excitation energies of primary hot isotopes in heavy ion collisions near the Fermi energy

    NASA Astrophysics Data System (ADS)

    Rodrigues, M. R. D.; Lin, W.; Liu, X.; Huang, M.; Zhang, S.; Chen, Z.; Wang, J.; Wada, R.; Kowalski, S.; Keutgen, T.; Hagel, K.; Barbui, M.; Bottosso, C.; Bonasera, A.; Natowitz, J. B.; Materna, T.; Qin, L.; Sahu, P. K.; Schmidt, K. J.

    2013-09-01

    The excitation energies of the primary hot isotopes in multifragmentation events are experimentally reconstructed in the reaction system 64Zn + 112Sn at 40 MeV/nucleon. A kinematical focusing method is employed to evaluate the multiplicities of the evaporated light particles associated with isotopically identified fragments with 3≤Z≤14. Angular distributions of the velocity spectra of light charged particles and neutrons associated with trigger isotopes are examined. A moving source fit is used to separate the kinematically correlated particles, evaporated from the parents of the detected isotopes, from the uncorrelated particles originating from other sources. The latter are evaluated experimentally relative to those in coincidence with the Li isotopes. A parameter, k, is used to adjust the yield of the uncorrelated particles for different trigger isotopes. For each experimentally detected isotope, the multiplicities, apparent temperatures, and k values for n, p, d, t, and α particles are extracted. Using the extracted values, the excitation energies of the primary hot isotopes are reconstructed employing a Monte Carlo method. The extracted excitation energies are in the range of 1 to 4 MeV/nucleon but show a significant decreasing trend as a function of A for a given Z of the isotopes. The results are compared with those of antisymmetrized molecular dynamics (AMD) and statistical multifragmentation model (SMM) simulations. While some of the experimental characteristics are predicted partially by each model, neither simulation reproduces the overall characteristics of the experimental results.

  18. 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…

  19. Anomalous Behavior of 2+ Excitations of Tellurium Isotopes around N = 82

    NASA Astrophysics Data System (ADS)

    Terasaki, J.; Engel, J.; Nazarewicz, W.; Stoitsov, M.

    2003-10-01

    In certain neutron-rich Te isotopes, a decrease in the energy of the first excited 2+ state is accompanied by a decrease in the E2 strength to that state from the ground state, contradicting simple systematics and general intuition about quadrupole collectivity. We use a separable quadrupole-plus-pairing Hamiltonian and the quasiparticle random phase approximation to calculate energies, B(E2,0+ → 2+) strengths, and g factors for the lowest 2+ states near 132Sn (Z ≥ 50). We trace the anomalous behavior in the Te isotopes to a reduced neutron pairing above the N = 82 magic gap. In addition, we briefly discuss the magicity of 68Ni.

  20. Monopole Modes of Excitation in Deformed Neutron-rich Mg Isotopes

    SciTech Connect

    Yoshida, Kenichi

    2009-08-26

    The giant monopole resonance (GMR) and the low-frequency mode of monopole excitation in neutron-rich magnesium isotopes close to the drip line are investigated by means of the deformed Hartree-Fock-Bogoliubov and quasiparticle random-phase approximations. It is found that the GMR has a two-peak structure due to the deformation. The lower-energy resonance is generated associated with the coupling to the K{sup p}i = 0{sup +} component of the giant quadrupole resonance. Besides the GMR, we obtain the soft K{sup p}i = 0{sup +} mode below the neutron emission threshold energy.

  1. Excitation energies in neutron-rich rare isotopes as indicators of changing shell structure

    NASA Astrophysics Data System (ADS)

    Gade, Alexandra

    2015-09-01

    The quest for a predictive model of atomic nuclei fuels experimental and theoretical research programs worldwide. The properties of rare isotopes emerge as crucial ingredients for the development of nuclear models valid also towards the nucleon driplines. Many important aspects of the interactions between the constituent protons and neutrons are amplified in the regime of large isospin and can best be isolated and characterized there. The energies of excited states offer a unique view into the structure of nuclei and are often some of the first quantities accessible by experiment. Excitation energies can be measured directly and in model-independent ways and thus are among the key observables that can guide our understanding of atomic nuclei.

  2. Ground- and excited-state proton transfers in reversed micelles. Polarity restrictions and isotope effects

    SciTech Connect

    Politi, M.J.; Brandt, O.; Fendler, J.H.

    1985-05-23

    Ground- and excited-state proton transfers have been investigated with 8-hydroxy-1,3,6-pyrenetrisulfonate, POH, in sodium bis(2-ethylhexyl) sulfosuccinate, AOT, reversed micelle solubilized water pools in isooctane. Since POH is a much stronger acid in the singlet excited state, (POH)*, than in the ground state (pK/sub a/ = 7.2, pK/sub a/* = 0.5), excitation of POH by 1-5-mJ, 8-ns, 353-nm laser pulses, at pH values such that pK/sub a/* < pH < pK/sub a/, results in the dissociation of POH, governed by k/sub off/*. PO/sup -/ reprotonation rate, K/sub on/ values, have been determined by laser flash photolysis. In reversed micelles k/sub on/ values were found to depend on the water-to-AOT ratio(w values). Deuterium solvent isotope effects of 1.3 and 2.2 have been determined for k/sub on//k/sub on/(D/sub 2/O) in w = 33 and 12 AOT solubilized reversed micelles in isooctane. Combining these values with pK/sub a/ of POH led to isotope effects of 7.8 and 8.4 on k/sub off/ in the corresponding solutions. Steady-state and subnanosecond time-resolved fluorescence measurements have been utilized for assessing POH excited-state deprotonation, governed by k/sub off/*(D/sub 2/O), and reprotonation, governed by k/sub on/*(D/sub 2/O), in pure D/sub 2/O and in AOT entrapped water and AOT-d entrapped D/sub 2/O pools in isooctane. 51 references, 10 figures, 6 tables.

  3. Low-lying excited states in the neutron-deficient isotopes 163Os and 165Os

    NASA Astrophysics Data System (ADS)

    Drummond, M. C.; Joss, D. T.; Page, R. D.; Simpson, J.; O'Donnell, D.; Andgren, K.; Bianco, L.; Cederwall, B.; Darby, I. G.; Eeckhaudt, S.; Gomez-Hornillos, M. B.; Grahn, T.; Greenlees, P. T.; Hadinia, B.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Leppänen, A.-P.; Leino, M.; Nyman, M.; Pakarinen, J.; Rahkila, P.; Sandzelius, M.; Sapple, P. J.; Sarén, J.; Saygi, B.; Scholey, C.; Sorri, J.; Thomson, J.; Uusitalo, J.; Venhart, M.

    2013-05-01

    Excited states in the neutron-deficient isotopes 163Os and 165Os were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The 163Os and 165Os nuclei were populated via the 106Cd(60Ni,3n) and 92Mo(78Kr,2p3n) reactions at bombarding energies of 270 MeV and 357 MeV, respectively. Gamma-ray emissions from these nuclei have been established unambiguously using the recoil-decay tagging technique and a coincidence analysis has allowed level schemes to be established. These results suggest that the yrast states are based upon negative-parity configurations originating from the νf7/2 and νh9/2 orbitals.

  4. Low-lying dipole excitations in vibrational nuclei: The Cd isotopic chain studied in photon scattering experiments

    SciTech Connect

    Kohstall, C.; Belic, D.; Kneissl, U.; Nord, A.; Pitz, H.H.; Scheck, M.; Stedile, F.; Brentano, P. von; Fransen, C.; Gade, A.; Herzberg, R.-D.; Jolie, J.; Linnemann, A.; Pietralla, N.; Werner, V.; Yates, S.W.

    2005-09-01

    High-resolution nuclear resonance fluorescence experiments (NRF) were performed on {sup 110,111,112,114,116}Cd at the bremsstrahlung facility of the 4.3-MV Dynamitron accelerator in Stuttgart to study the low-lying dipole strength distributions in these vibrational nuclei. Numerous excited states, most of them previously unknown, were observed in the excitation energy range up to 4 MeV. Detailed spectroscopic information has been obtained on excitation energies, spins, decay widths, decay branchings, and transition probabilities. For states in the even-even isotopes {sup 110,112,114,116}Cd, parities could be assigned from linear polarization measurements. Together with our previous results for {sup 108,112,113,114}Cd from NRF studies without polarization measurements, systematics was established for the dipole strength distributions of the stable nuclei within the Cd isotopic chain. The results are discussed with respect to the systematics of E1 two-phonon excitations and mixed-symmetry states in even-even nuclei near the Z=50 shell closure and the fragmentation of these excitation modes in the odd-mass Cd isotopes.

  5. 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.

  6. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    SciTech Connect

    Pajtler, M. Varga; Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N.; Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J.; Gadea, A.; Haas, F.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F.; Märginean, N.; Pollarolo, G.; and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  7. Recoil distance transmission method: Measurement of interaction cross sections of excited states with fast rare-isotope beams

    NASA Astrophysics Data System (ADS)

    Kobayashi, N.; Whitmore, K.; Iwasaki, H.

    2016-09-01

    The possible appearance of nuclear halos in ground and excited states close to the particle-decay threshold is of great importance in the investigation of nuclear structure and few-body correlations at the limit of stability. In order to obtain direct evidence of the halo structure manifested in nuclear excited states, we have considered a new method to measure the interaction cross sections of excited states. The combination of the transmission method and the recoil distance Doppler-shift method with a plunger device enables us to measure the number of interactions of the excited states in a target. Formulae to determine the interaction cross section are derived, and key issues to realize measurements are discussed. Dominant sources of errors are uncertainties in the excited-state lifetimes and γ-ray yields. We examine prototype experiments and perform simulations to study the impact of each uncertainty on the final result. This method provides a novel opportunity to perform cross section measurements on the excited states of rare isotopes.

  8. 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.

  9. Studies on the optogalvanic effect and isotope-selective excitation of ytterbium in a hollow cathode discharge lamp using a pulsed dye laser.

    PubMed

    Kumar, Pankaj; Kumar, Jitendra; Prakash, Om; Saini, Vinod K; Dixit, Sudhir K; Nakhe, Shankar V

    2013-09-01

    This paper presents studies on the pulsed optogalvanic effect and isotope-selective excitation of Yb 555.648 nm (0 cm(-1) → 17 992.007 cm(-1)) and 581.067 nm (17 992.007 cm(-1) → 35 196.98 cm(-1)) transitions, in a Yb/Ne hollow cathode lamp. The Yb atoms were excited by narrow linewidth (500-1000 MHz) Rh110 and Rh6G dye based pulsed lasers. Optogalvanic signal inversion for ground state transition at 555.648 nm was observed beyond a hollow cathode discharge current of 8.5 mA, in contrast to normal optogalvanic signal at 581.067 nm up to maximum current of 14 mA. The isotope-selective excitation studies of Yb were carried out by recording Doppler limited optogalvanic signals as a function of dye laser wavelength. For the 581.067 nm transition, three even isotopes, (172)Yb, (174)Yb, and (176)Yb, and one odd isotope, (171)Yb, were clearly resolved. These data were compared with selective isotope excitation by 10 MHz linewidth continuous-wave dye laser. For 555.648 nm transition, isotopes were not clearly resolved, although isotope peaks of low modulation were observed. PMID:24067634

  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. Study of dipole excitations and the single particle structure of neutron rich Ni isotopes

    NASA Astrophysics Data System (ADS)

    Mahata, K.; Paschalis, S.; Adrich, P.; Aksouh, F.; Aumann, T.; Babilon, M.; Behr, K.-H.; Benlliure, J.; Berg, T.; Boehmer, M.; Boretzky, K.; Brünle, A.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Pramanik, U. Datta; Deveaux, L.; Elvers, M.; Emling, H.; Fernandez-Dominguez, B.; Gorska, M.; Hüller, W.; Ickert, G.; Johansson, H.; Junghans, A.; Karagiannis, C.; Kern, L.; Kiselev, O.; Klimkiewicz, A.; Kurz, N.; Labiche, M.; Le Bleis, T.; Lemmon, R.; Lindenberg, K.; Litvinov, Y.; Maierbeck, P.; Müller, S.; Nilsson, T.; Nociforo, C.; Palit, R.; Prokopowicz, W.; Rossi, D.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.

    2008-05-01

    An experiment was performed using the FRS-LAND setup at GSI to study the dipole strength distributions above neutron separation threshold for neutron-rich Ni isotopes. Measurements, using the same experimental setup, were also carried out to extract single particle occupancies via knockout reactions to investigate the structure and magicity of the neutron-rich Ni isotopes. The status of the data analysis and preliminary results are presented.

  12. On the strong and selective isotope effect in the UV excitation of N2 with implications toward the nebula and Martian atmosphere

    PubMed Central

    Muskatel, B. H.; Remacle, F.; Thiemens, Mark H.; Levine, R. D.

    2011-01-01

    Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physical basis for an additional isotope effect during photolysis of molecular nitrogen due to the coupling of valence and Rydberg excited states. The origin of this isotope effect is shown to be the coupling of diabatic electronic states of different bonding nature that occurs after the excitation of these states. This coupling is characteristic of energy regimes where two or more excited states are nearly crossing or osculating. A signature of the resultant isotope effect is a window of rapid variation in the otherwise smooth distribution of oscillator strengths vs. frequency. The reference for the discussion is the numerical solution of the time dependent Schrödinger equation for both the electronic and nuclear modes with the light field included as part of the Hamiltonian. Pumping is to all extreme UV dipole-allowed, valence and Rydberg, excited states of N2. The computed absorption spectra are convoluted with the solar spectrum to demonstrate the importance of including this isotope effect in planetary, interstellar molecular cloud, and nebular photochemical models. It is suggested that accidental resonance with strong discrete lines in the solar spectrum such as the CIII line at 97.703 nm can also have a marked effect. PMID:21441106

  13. On the strong and selective isotope effect in the UV excitation of N2 with implications toward the nebula and Martian atmosphere.

    PubMed

    Muskatel, B H; Remacle, F; Thiemens, Mark H; Levine, R D

    2011-04-12

    Isotopic effects associated with molecular absorption are discussed with reference to natural phenomena including early solar system processes, Titan and terrestrial atmospheric chemistry, and Martian atmospheric evolution. Quantification of the physicochemical aspects of the excitation and dissociation processes may lead to enhanced understanding of these environments. Here we examine a physical basis for an additional isotope effect during photolysis of molecular nitrogen due to the coupling of valence and Rydberg excited states. The origin of this isotope effect is shown to be the coupling of diabatic electronic states of different bonding nature that occurs after the excitation of these states. This coupling is characteristic of energy regimes where two or more excited states are nearly crossing or osculating. A signature of the resultant isotope effect is a window of rapid variation in the otherwise smooth distribution of oscillator strengths vs. frequency. The reference for the discussion is the numerical solution of the time dependent Schrödinger equation for both the electronic and nuclear modes with the light field included as part of the Hamiltonian. Pumping is to all extreme UV dipole-allowed, valence and Rydberg, excited states of N(2). The computed absorption spectra are convoluted with the solar spectrum to demonstrate the importance of including this isotope effect in planetary, interstellar molecular cloud, and nebular photochemical models. It is suggested that accidental resonance with strong discrete lines in the solar spectrum such as the CIII line at 97.703 nm can also have a marked effect. PMID:21441106

  14. 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)

  15. 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

  16. Observation of an unexpected negative isotope shift in +229Th and its theoretical explanation

    NASA Astrophysics Data System (ADS)

    Okhapkin, M. V.; Meier, D. M.; Peik, E.; Safronova, M. S.; Kozlov, M. G.; Porsev, S. G.

    2015-08-01

    We have measured the hyperfine structure and isotope shifts of the 402.0- and 399.6-nm resonance lines in +229Th . These transitions could provide pathways towards the excitation of the 229Th low-energy isomeric nuclear state. An unexpected negative isotope shift relative to +232Th is observed for the 399.6-nm line, indicating a strong Coulomb coupling of the excited state to the nucleus. We have developed an all-order approach to the isotope shift calculations that is generally applicable to heavy atoms and ions with several valence electrons. The theoretical calculations provide an explanation for the negative isotope shift of the 399.6-nm transition and yield a corrected classification of the excited state. The calculated isotope shifts are in good agreement with experimental values.

  17. Rotational spectra of isotopic species of methyl cyanide, CH3CN, in their v8 = 1 excited vibrational states

    NASA Astrophysics Data System (ADS)

    Müller, Holger S. P.; Drouin, Brian J.; Pearson, John C.; Ordu, Matthias H.; Wehres, Nadine; Lewen, Frank

    2016-02-01

    Context. Methyl cyanide is an important trace molecule in space, especially in star-forming regions where it is one of the more common molecules used to derive kinetic temperatures. Aims: We want to obtain accurate spectroscopic parameters of minor isotopologs of methyl cyanide in their lowest excited ν8 = 1 vibrational states to support astronomical observations, in particular, with interferometers such as ALMA. Methods: The laboratory rotational spectrum of methyl cyanide in natural isotopic composition has been recorded from the millimeter to the terahertz regions. Results: Transitions with good signal-to-noise ratios could be identified for the three isotopic species CH313CN, 13CH3CN, and CH3C15N up to about 1.2 THz (J'' ≤ 66). Accurate spectroscopic parameters were obtained for all three species. Conclusions: The present data were already instrumental in identifying ν8 = 1 lines of methyl cyanide with one 13C in IRAM 30 m and ALMA data toward Sagittarius B2(N).

  18. Corrigendum to: "Shape dynamics in neutron-rich Kr isotopes: Coulomb excitation of 92Kr, 94Kr and 96Kr" [Nucl. Phys. A 899 (2013) 1-28

    NASA Astrophysics Data System (ADS)

    Albers, M.; Nomura, K.; Warr, N.; Blazhev, A.; Jolie, J.; Mücher, D.; Bastin, B.; Bauer, C.; Bernards, C.; Bettermann, L.; Bildstein, V.; Butterworth, J.; Cappellazzo, M.; Cederkäll, J.; Cline, D.; Darby, I.; Das Gupta, S.; Daugas, J. M.; Davinson, T.; De Witte, H.; Diriken, J.; Filipescu, D.; Fiori, E.; Fransen, C.; Gaffney, L. P.; Georgiev, G.; Gernhäuser, R.; Hackstein, M.; Heinze, S.; Hess, H.; Huyse, M.; Jenkins, D.; Konki, J.; Kowalczyk, M.; Kröll, T.; Krücken, R.; Litzinger, J.; Lutter, R.; Marginean, N.; Mihai, C.; Moschner, K.; Napiorkowski, P.; Nara Singh, B. S.; Nowak, K.; Pakarinen, J.; Pfeiffer, M.; Radeck, D.; Reiter, P.; Rigby, S.; Robledo, L. M.; Rodríguez-Guzmán, R.; Rudigier, M.; Scheck, M.; Seidlitz, M.; Siebeck, B.; Simpson, G.; Thöle, P.; Thomas, T.; Van de Walle, J.; Van Duppen, P.; Vermeulen, M.; Voulot, D.; Wadsworth, R.; Wenander, F.; Wimmer, K.; Zell, K. O.; Zielinska, M.

    2016-03-01

    Recently, an erratum to our Letter [1] was published concerning the E2 transition operator used to calculate the theoretical B (E2) values [2]. The E2 transition operator used was not TA(E 2) =eπQˆπ +eνQˆν as quoted in the text on page 3 of Ref. [1]. Instead the operator TB(E 2) =eπ(sπ† d˜π + dπ† s˜π) (2) +eν(sν† d˜ν + dν† s˜ν) (2) +χπ(dπ† d˜π) (2) +χν(dν† d˜ν) (2) was used to calculate the B (E2) values in the IBM-2 in Ref. [1], while the Q (21+) values were calculated using TA(E 2). In order to be consistent we have recalculated with this operator the Q (21+) values which were shown in Fig. 18. The corrected values (Q(21+) B) are shown in Fig. 1 compared to the values from the original paper (Q(21+) A). For completeness, we also give the corresponding B (E2) values calculated using TA(E 2) in Fig. 1. This correction does not change the main result and the conclusion of the published Letter.

  19. Low-energy structure of the even-A {sup 96-104}Ru isotopes via g-factor measurements

    SciTech Connect

    Taylor, M. J.; Bentley, M. A.; Guerdal, G.; Kumbartzki, G.; Benczer-Koller, N.; Sharon, Y. Y.; Stuchbery, A. E.; Berant, Z.; Casperson, R. J.; Casten, R. F.; Heinz, A.; Ilie, G.; McCutchan, E. A.; Qian, J.; Werner, V.; Williams, E.; Winkler, R.; Luettke, R.; Shoraka, B.

    2011-04-15

    The transient-field-perturbed angular correlation technique was used with Coulomb excitation in inverse kinematics to perform a systematic measurement of the g factors of the first excited 2{sub 1}{sup +} states in the stable even-A isotopes {sup 96-104}Ru. The measurements have been made relative to one another under matched kinematic conditions and include a measurement of g(2{sub 1}{sup +})=+0.47(3) in {sup 96}Ru.

  20. Transient resonance Raman spectra of benzophenone and its four isotopic analogues in the lowest excited triplet state

    SciTech Connect

    Tahara, T.; Hamaguchi, H.; Tasumi, M.

    1987-11-05

    Transient resonance Raman spectra of T/sub 1/ benzophenone (T/sub 1/BP) and its four isotopic analogues in carbon tetrachloride solutions were measured. Vibrational assignments of eight T/sub 1/ bands have been made on the basis of the observed isotopic frequency shifts. The assignments clarified the following three points concerning the structure of T/sub 1/ BP in solution. (1) The CO bond order in T/sub 1/ BP is much lower than that in the ground-state benzophenone (S/sub 0/ BP). The CO stretching frequency in T/sub 1/ is found to be 1222 cm/sup -1/, whereas the corresponding value in S/sub 0/ is 1665 cm/sup -1/. The former frequency indicates a single-bond-like character of the CO bonding in the T/sub 1/ state. (2) Vibrational frequencies of several ring modes show marked downshifts in going from S/sub 0/ to T/sub 1/. This suggests the delocalization of the ..pi..* electron into the ring part. (3) The assignment (1302 cm/sup -1/) of the symmetric C-phenyl stretch mode in the T/sub 1/ withdraws S/sub 0/ absorption spectrum is questioned. According to the present assignment, the frequency of this mode (approx. 1100 cm/sup -1/) is slightly lower than that in the ground state (1150 cm/sup -1/). The simple quantum chemical picture of T/sub 1/ BP, which predicted the increase of the C-phenyl bond order with the ..pi..* withdraws n excitation, should therefore be reconsidered.

  1. 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.

  2. Search for the gamma-branch of the shape isomers of separated U isotopes using muon for nuclide excitation

    SciTech Connect

    Mireshghi, A.

    1982-12-01

    We have searched for back-decay gamma rays from the shape isomeric states in /sup 235/U, /sup 236/U, and /sup 238/U possibly excited in muon radiationless transition. The energies and intensities of gamma rays following muon atomic capture were measured as a function of time after muon stopping. Background was suppressed by requiring that the candidate gamma ray be followed by another gamma ray (..mu..-capture gamma ray). The prompt gamma-ray spectra included the U-muonic x rays. The measured /sup 235/U and /sup 238/U x-ray energies were in good agreement with previously reported results. The x-ray spectrum from /sup 236/U has not been previously reported. The /sup 236/U spectrum is very similar to that of /sup 238/U, except that the K x-rays exhibit an isotope shift of approximately 20 keV, the /sup 236/U energies being higher. In the analysis of the delayed spectra of /sup 236/U and /sup 238/U using the GAMANL peak searching program, and with an effective lower-limit detection efficiency of .15% per stopping muon, no candidate gamma rays for the back decay transitions from the shape isomeric state were observed.

  3. 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.

  4. 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.

  5. 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.

  6. Precise measurements of 203 Tl and 205 Tl excited state hyperfine splittings and isotope shifts using two-step vapor cell spectroscopy

    NASA Astrophysics Data System (ADS)

    Majumder, P. K.; Cheng, Sau Man; Rupasinghe, P. M.

    2016-05-01

    We have undertaken a series of high-precision atomic structure measurement in thallium to test ongoing ab initio atomic structure calculations of relevance to symmetry violation tests in this element. We are currently completing two-step spectroscopy measurements of the 8P1 / 2 and 8P3 / 2 hyperfine structure and isotope shift using a heated thallium vapor cell and two external cavity semiconductor diode lasers. One laser, locked to the thallium 6P1 / 2 --> 7S1 / 2 378 nm transition excites one or both naturally-occurring isotopes to an intermediate state. A second red laser overlaps the UV beam within the thallium vapor cell in both a co-propagating and counter-propagating configuration. Analysis of subsequent Doppler-free absorption spectra of the 7S1 / 2 --> 8P1 / 2 , 3 / 2 visible transitions allows us to extract both hyperfine and isotope shift information for these excited states with uncertainties below 1 MHz. Frequency modulation of the red laser provides convenient in situ frequency calibration. Recent measurements in our group have shown significant discrepancies from older hyperfine structure measurements in thallium excited states. Current results will be presented. Work supported by NSF Grant # 1404206.

  7. Reply to "Comment on `Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit' "

    NASA Astrophysics Data System (ADS)

    Gebremedhin, Daniel H.; Weatherford, Charles A.

    2015-02-01

    This is a response to the comment we received on our recent paper "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit." In that paper, we introduced a computational algorithm that is appropriate for solving stiff initial value problems, and which we applied to the one-dimensional time-independent Schrödinger equation with a soft Coulomb potential. We solved for the eigenpairs using a shooting method and hence turned it into an initial value problem. In particular, we examined the behavior of the eigenpairs as the softening parameter approached zero (hard Coulomb limit). The commenters question the existence of the ground state of the hard Coulomb potential, which we inferred by extrapolation of the softening parameter to zero. A key distinction between the commenters' approach and ours is that they consider only the half-line while we considered the entire x axis. Based on mathematical considerations, the commenters consider only a vanishing solution function at the origin, and they question our conclusion that the ground state of the hard Coulomb potential exists. The ground state we inferred resembles a δ (x ) , and hence it cannot even be addressed based on their argument. For the excited states, there is agreement with the fact that the particle is always excluded from the origin. Our discussion with regard to the symmetry of the excited states is an extrapolation of the soft Coulomb case and is further explained herein.

  8. 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.

  9. Deuterium isotope effect on femtosecond solvation dynamics in an ionic liquid microemulsion: an excitation wavelength dependence study.

    PubMed

    Sasmal, Dibyendu Kumar; Mojumdar, Supratik Sen; Adhikari, Aniruddha; Bhattacharyya, Kankan

    2010-04-01

    The deuterium isotope effect on the solvation dynamics and the anisotropy decay of coumarin 480 (C480) in a room temperature ionic liquid (RTIL) microemulsion is studied by femtosecond up-conversion. The microemulsion consists of the RTIL 1-pentyl-3-methyl-imidazolium tetra-fluoroborate ([pmim][BF(4)]) in triton X-100 (TX-100)/benzene. Replacement of H(2)O by D(2)O in the microemulsion causes retardation of solvation dynamics. The average solvation time of C480 (tau(s)) in RTIL microemulsion with 5 wt % D(2)O is approximately 1.5-1.7 times slower compared to that in the H(2)O containing RTIL microemulsion. This suggests that the main species in the microemulsion responsible for solvation is the water molecules. In both D(2)O and H(2)O containing RTIL microemulsion, the solvation dynamics exhibits marked dependence on the excitation wavelength (lambda(ex)) and becomes about 15 times faster as lambda(ex) increases from 375 to 435 nm. This is ascribed to the structural heterogeneity in the RTIL microemulsion. For lambda(ex) = 375 nm, the region near the TX-100 surfactant is probed where bound water molecules cause slow solvation dynamics. At 435 nm, the RTIL pool is selected where the water molecules are more mobile and hence gives rise to faster solvation. The average time constant of anisotropy decay shows opposite dependence on lambda(ex) and increases about 2.5-fold from 180 ps at lambda(ex) = 375 nm to 500 ps at lambda(ex) = 435 nm for D(2)O containing RTIL microemulsion. The slower anisotropy decay at lambda(ex) = 435 nm is ascribed to the higher viscosity of RTIL which causes greater friction at the core. PMID:20235504

  10. Sub-Doppler two-photon-excitation Rydberg spectroscopy of atomic xenon: mass-selective studies of isotopic and hyperfine structure

    NASA Astrophysics Data System (ADS)

    Kono, Mitsuhiko; He, Yabai; Baldwin, Kenneth G. H.; Orr, Brian J.

    2016-03-01

    Mass-selective sub-Doppler two-photon excitation (TPE) spectroscopy is employed to resolve isotopic contributions for transitions to high-energy Rydberg levels of xenon in an atomic beam, using narrowband pulses of coherent ultraviolet light at 205-213 nm generated by nonlinear-optical conversion processes. Previous research (Kono et al 2013 J. Phys. B: At. Mol. Opt. Phys. 46 35401), has determined isotope energy shifts and hyperfine structure for 33 high-energy Rydberg levels of gas-phase xenon and accessed Rydberg levels at TPE energies in the range of 94 100-97 300 cm-1 with unprecedented spectroscopic resolution. The new isotopic-mass-resolved results were obtained by adding a pulsed free-jet atomic-beam source and a mass-selective time-of-flight detector to the apparatus in order to discern individual xenon isotopes and extract previously unresolved spectroscopic information. Resulting isotope energy shifts and hyperfine-coupling parameters are examined with regard to trends in principal quantum number n and in atomic angular-momentum quantum numbers, together with empirical and theoretical precedents for such trends.

  11. 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.

  12. 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.

  13. Control of Electron Excitation and Localization in the Dissociation of H{sub 2}{sup +} and Its Isotopes Using Two Sequential Ultrashort Laser Pulses

    SciTech Connect

    He Feng; Ruiz, Camilo; Becker, Andreas

    2007-08-24

    We study the control of dissociation of the hydrogen molecular ion and its isotopes exposed to two ultrashort laser pulses by solving the time-dependent Schroedinger equation. While the first ultraviolet pulse is used to excite the electron wave packet on the dissociative 2p{sigma}{sub u} state, a second time-delayed near-infrared pulse steers the electron between the nuclei. Our results show that by adjusting the time delay between the pulses and the carrier-envelope phase of the near-infrared pulse, a high degree of control over the electron localization on one of the dissociating nuclei can be achieved (in about 85% of all fragmentation events). The results demonstrate that current (sub-)femtosecond technology can provide a control over both electron excitation and localization in the fragmentation of molecules.

  14. Low-energy dipole excitations in neon isotopes and N=16 isotones within the quasiparticle random-phase approximation and the Gogny force

    SciTech Connect

    Martini, M.; Peru, S.; Dupuis, M.

    2011-03-15

    Low-energy dipole excitations in neon isotopes and N=16 isotones are calculated with a fully consistent axially-symmetric-deformed quasiparticle random phase approximation (QRPA) approach based on Hartree-Fock-Bogolyubov (HFB) states. The same Gogny D1S effective force has been used both in HFB and QRPA calculations. The microscopical structure of these low-lying resonances, as well as the behavior of proton and neutron transition densities, are investigated in order to determine the isoscalar or isovector nature of the excitations. It is found that the N=16 isotones {sup 24}O, {sup 26}Ne, {sup 28}Mg, and {sup 30}Si are characterized by a similar behavior. The occupation of the 2s{sub 1/2} neutron orbit turns out to be crucial, leading to nontrivial transition densities and to small but finite collectivity. Some low-lying dipole excitations of {sup 28}Ne and {sup 30}Ne, characterized by transitions involving the {nu}1d{sub 3/2} state, present a more collective behavior and isoscalar transition densities. A collective proton low-lying excitation is identified in the {sup 18}Ne nucleus.

  15. Measurement of the 92,93,94,100Mo(γ,n) reactions by Coulomb Dissociation

    NASA Astrophysics Data System (ADS)

    Göbel, K.; Adrich, P.; Altstadt, S.; Alvarez-Pol, H.; Aksouh, F.; Aumann, T.; Babilon, M.; Behr, K.-H.; Benlliure, J.; Berg, T.; Böhmer, M.; Boretzky, K.; Brünle, A.; Beyer, R.; Casarejos, E.; Chartier, M.; Cortina-Gil, D.; Chatillon, A.; Datta Pramanik, U.; Deveaux, L.; Elvers, M.; Elze, T. W.; Emling, H.; Erhard, M.; Ershova; Fernandez-Dominguez, B.; Geissel, H.; Górska, M.; Heftrich, T.; Heil, M.; Hellstroem, M.; Ickert, G.; Johansson, H.; Junghans, A. R.; Käppeler, F.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindenberg, K.; Litvinov, Y. A.; Maierbeck, P.; Movsesyan, A.; Müller, S.; Nilsson, T.; Nociforo, C.; Paar, N.; Palit, R.; Paschalis, S.; Plag, R.; Prokopowicz, W.; Reifarth, R.; Rossi, D. M.; Schnorrenberger, L.; Simon, H.; Sonnabend, K.; Sümmerer, K.; Surówka, G.; Vretenar, D.; Wagner, A.; Walter, S.; Waluś, W.; Wamers, F.; Weick, H.; Weigand, M.; Winckler, N.; Winkler, M.; Zilges, A.

    2016-01-01

    The Coulomb Dissociation (CD) cross sections of the stable isotopes 92,94,100Mo and of the unstable isotope 93Mo were measured at the LAND/R3B setup at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of 92,94Mo and 96,98Ru in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction 93Mo(γ,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94Mo(γ,n) reaction is presented. Further analysis will complete the experimental database for the (γ,n) production chain of the p-isotopes of molybdenum.

  16. Isotope separation by photochromatography

    DOEpatents

    Suslick, Kenneth S.

    1977-01-01

    An isotope separation method which comprises physically adsorbing an isotopically mixed molecular species on an adsorptive surface and irradiating the adsorbed molecules with radiation of a predetermined wavelength which will selectively excite a desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thereby separate them from the unexcited undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes.

  17. Isotope separation by photochromatography

    DOEpatents

    Suslick, K.S.

    1975-10-03

    A photochromatographic method for isotope separation is described. An isotopically mixed molecular species is adsorbed on an adsorptive surface, and the adsorbed molecules are irradiated with radiation of a predetermined wavelength which will selectively excite desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thus separate them from the undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes. (BLM)

  18. Microwave ac Conductivity Spectrum of a Coulomb Glass

    SciTech Connect

    Lee, Mark; Stutzmann, M. L.

    2001-07-30

    We report the first observation of the transition between interacting and noninteracting behavior in the ac conductivity spectrum {sigma}({omega}) of a doped semiconductor in its Coulomb glass state near T=0 K . The transition manifests itself as a crossover from approximately linear frequency dependence below {approx}10 GHz , to quadratic dependence above {approx}15 GHz . The sharpness of the transition and the magnitude of the crossover frequency strongly suggest that the transition is driven by photon-induced excitations across the Coulomb gap, in contrast to existing theoretical descriptions.

  19. 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.

  20. Limiting temperatures of neutron rich nuclei: A possible interpretation of data from isotope yield ratios

    SciTech Connect

    Natowitz, J.B.; Hagel, K.; Wada, R.; Majka, Z.; Gonthier, P.; Li, J.; Mdeiwayeh, N.; Xiao, B.; Zhao, Y.

    1995-11-01

    The recent ALADIN report of limiting temperatures for nuclear disassembly, derived from measurements of isotopic ratios for He and Li nuclei, is discussed. It is suggested that the entire excitation energy dependence which is observed may result from the fact that limiting temperatures for the onset of Coulomb instability are being measured for progressively lighter neutron rich nuclei as the excitation energy per nucleon increases. While the basic observation of plateauing in the intermediate excitation energy range remains valid, the higher excitation results may not signal entry into the vapor phase. The ALADIN result for {ital A}{approx}125, when combined with lower energy data, indicates a plateau temperature near 6.5 MeV over the range of 3--11 MeV/nucleon initial excitation energy.

  1. Discovery of Highly Excited Long-Lived Isomers in Neutron-Rich Hafnium and Tantalum Isotopes through Direct Mass Measurements

    SciTech Connect

    Reed, M. W.; Cullen, I. J.; Walker, P. M.; Deo, A. Y.; Kempley, R. S.; Swan, T. P. D.; Litvinov, Yu. A.; Winckler, N.; Blaum, K.; Bosch, F.; Dimopoulou, C.; Farinon, F.; Heil, M.; Knoebel, R.; Kozhuharov, C.; Kurcewicz, J.; Kuzminchuk, N.; Litvinov, S.; Nociforo, C.; Nolden, F.

    2010-10-22

    A study of cooled {sup 197}Au projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides {sup 183,184,186}Hf and {sup 186,187}Ta. The results support the prediction of a strongly favored isomer region near neutron number 116.

  2. 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.

  3. Rates of complex formation in collisions of rotationally excited homonuclear diatoms with ions at very low temperatures: Application to hydrogen isotopes and hydrogen-containing ions

    SciTech Connect

    Dashevskaya, E.I.; Litvin, I.; Nikitin, E.E.; Troe, J.

    2005-05-08

    State-selected rate coefficients for the capture of ground and rotationally excited homonuclear molecules by ions are calculated, for low temperatures, within the adiabatic channel classical (ACCl) approximation, and, for zero temperature, via an approximate calculation of the Bethe limit. In the intermediate temperature range, the accurate quantal rate coefficients are calculated for j=0 and j=1 states of hydrogen isotopes (H{sub 2}, HD, and D{sub 2}) colliding with hydrogen-containing ions, and simple analytical expressions are suggested to approximate the rate coefficients. For the ground rotational state of diatoms, the accurate quantal rate coefficients are higher compared to their ACCl counterparts, while for the first excited rotational state the reverse is true. The physical significance of quantum effects for low-temperature capture and the applicability of the statistical description of capture are considered. Particular emphasis is given to the role of Coriolis interaction. The relevance of the present capture calculations for rates of ortho-para conversion of H{sub 2} in collisions with hydrogen-containing ions at low temperatures is discussed.

  4. Isotope separation

    DOEpatents

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  5. Nuclear spectroscopy study of the isotopes populated via multinucleon transfer in the 90Zr + 208Pb reaction

    SciTech Connect

    Ur, C. A.; Corradi, L.; Stefanini, A. M.; Behera, B. R.; Fioretto, E.; Gadea, A.; Latina, A.; Szilner, S.; Beghini, S.; Farnea, E.; Montagnoli, G.; Scarlassara, F.; Haas, F.; Pollarolo, G.

    2006-08-14

    The present work takes advantage of the multinucleon transfer mechanism between heavy reaction partners to study the population pattern of excited nuclear states in near spherical Zirconium isotopes following the 90Zr + 208Pb reaction at an energy closed to the Coulomb barrier. Both the projectile and the target are well known closed shell nuclei offering an optimum situation for clean experimental and theoretical conditions. Total kinetic energy loss (TKEL) distributions were compared with calculations performed with the GRAZING code. The ability to use the TKEL as a selection tool for the states at different excitation energies was shown.

  6. Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes

    NASA Astrophysics Data System (ADS)

    Kesteloot, N.; Bastin, B.; Gaffney, L. P.; Wrzosek-Lipska, K.; Auranen, K.; Bauer, C.; Bender, M.; Bildstein, V.; Blazhev, A.; Bönig, S.; Bree, N.; Clément, E.; Cocolios, T. E.; Damyanova, A.; Darby, I.; De Witte, H.; Di Julio, D.; Diriken, J.; Fransen, C.; García-Ramos, J. E.; Gernhäuser, R.; Grahn, T.; Heenen, P.-H.; Hess, H.; Heyde, K.; Huyse, M.; Iwanicki, J.; Jakobsson, U.; Konki, J.; Kröll, T.; Laurent, B.; Lecesne, N.; Lutter, R.; Pakarinen, J.; Peura, P.; Piselli, E.; Próchniak, L.; Rahkila, P.; Rapisarda, E.; Reiter, P.; Scheck, M.; Seidlitz, M.; Sferrazza, M.; Siebeck, B.; Sjodin, M.; Tornqvist, H.; Traykov, E.; Van De Walle, J.; Van Duppen, P.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.; Zielińska, M.

    2015-11-01

    Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po 196 ,198 ,200 ,202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po,202200, the transitional and diagonal matrix elements of the 21+ state are determined. In Po,198196 multistep Coulomb excitation is observed, populating the 41+,02+ , and 22+ states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from 196Po onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.

  7. 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.

  8. Spectroscopic Quadrupole Moments in Sr,9896 : Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N =60

    NASA Astrophysics Data System (ADS)

    Clément, E.; Zielińska, M.; Görgen, A.; Korten, W.; Péru, S.; Libert, J.; Goutte, H.; Hilaire, S.; Bastin, B.; Bauer, C.; Blazhev, A.; Bree, N.; Bruyneel, B.; Butler, P. A.; Butterworth, J.; Delahaye, P.; Dijon, A.; Doherty, D. T.; Ekström, A.; Fitzpatrick, C.; Fransen, C.; Georgiev, G.; Gernhäuser, R.; Hess, H.; Iwanicki, J.; Jenkins, D. G.; Larsen, A. C.; Ljungvall, J.; Lutter, R.; Marley, P.; Moschner, K.; Napiorkowski, P. J.; Pakarinen, J.; Petts, A.; Reiter, P.; Renstrøm, T.; Seidlitz, M.; Siebeck, B.; Siem, S.; Sotty, C.; Srebrny, J.; Stefanescu, I.; Tveten, G. M.; Van de Walle, J.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.; De Witte, H.; Wrzosek-Lipska, K.

    2016-01-01

    Neutron-rich Sr,9896 isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N =60 .

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. Investigating nuclear shell structure in the vicinity of 78Ni: Low-lying excited states in the neutron-rich isotopes Zn,8280

    NASA Astrophysics Data System (ADS)

    Shiga, Y.; Yoneda, K.; Steppenbeck, D.; Aoi, N.; Doornenbal, P.; Lee, J.; Liu, H.; Matsushita, M.; Takeuchi, S.; Wang, H.; Baba, H.; Bednarczyk, P.; Dombradi, Zs.; Fulop, Zs.; Go, S.; Hashimoto, T.; Honma, M.; Ideguchi, E.; Ieki, K.; Kobayashi, K.; Kondo, Y.; Minakata, R.; Motobayashi, T.; Nishimura, D.; Otsuka, T.; Otsu, H.; Sakurai, H.; Shimizu, N.; Sohler, D.; Sun, Y.; Tamii, A.; Tanaka, R.; Tian, Z.; Tsunoda, Y.; Vajta, Zs.; Yamamoto, T.; Yang, X.; Yang, Z.; Ye, Y.; Yokoyama, R.; Zenihiro, J.

    2016-02-01

    The low-lying level structures of nuclei in the vicinity of 78Ni were investigated using in-beam γ -ray spectroscopy to clarify the nature of the nuclear magic numbers Z =28 and N =50 in systems close to the neutron drip line. Nucleon knockout reactions were employed to populate excited states in 80Zn and 82Zn. A candidate for the 41+ level in 80Zn was identified at 1979(30) keV, and the lifetime of this state was estimated to be 136-67+92 ps from a line-shape analysis. Moreover, the energy of the 21+ state in 82Zn is reported to lie at 621(11) keV. The large drop in the 21+ energy at 82Zn indicates the presence of a significant peak in the E (21+) systematics at N =50 . Furthermore, the E (41+) /E (21+) and B (E 2 ;41+→21+) /B (E 2 ;21+→0g.s . +) ratios in 80Zn were deduced to be 1.32 (3 ) and 1 .12-60+80 , respectively. These results imply that 80Zn can be described in terms of two-proton configurations with a 78Ni core and are consistent with a robust N =50 magic number along the Zn isotopic chain. These observations, therefore, indicate a persistent N =50 shell closure in nuclei far from the line of β stability, which in turn suggests a doubly magic structure for 78Ni.

  14. 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.

  15. 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.

  16. 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.

  17. O(6)-symmetry breaking in the {gamma}-soft nucleus {sup 126}Xe and its evolution in the light stable xenon isotopes

    SciTech Connect

    Coquard, L.; Pietralla, N.; Leske, J.; Moeller, O.; Moeller, T.; Rainovski, G.; Ahn, T.; Bettermann, L.; Rother, W.; Carpenter, M. P.; Janssens, R. V. F.; Lister, C. J.; Zhu, S.; Werner, V.

    2011-04-15

    Low-lying collective states in {sup 126}Xe have been investigated via the {sup 12}C({sup 126}Xe,{sup 126}Xe{sup *}) projectile Coulomb excitation reaction at 399 MeV. The {gamma} decays were detected with the Gammasphere array. Coulomb excitation cross sections relative to the 2{sub 1}{sup +} state were obtained. Twenty-two absolute E2 transition strengths have been deduced. An sd- interacting boson model (IBM-1) fit agrees well with the new experimental data. This makes a quantitative test of O(6)-symmetry breaking in {sup 126}Xe possible. The measured absolute B(E2) values indicate a preservation of O(5) symmetry, while the O(6) symmetry is broken. The evolution of O(6)-symmetry breaking and of O(5)-symmetry conservation in the {sup 124,126,128}Xe isotopic chain is discussed.

  18. Spectroscopic Quadrupole Moments in {96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60.

    PubMed

    Clément, E; Zielińska, M; Görgen, A; Korten, W; Péru, S; Libert, J; Goutte, H; Hilaire, S; Bastin, B; Bauer, C; Blazhev, A; Bree, N; Bruyneel, B; Butler, P A; Butterworth, J; Delahaye, P; Dijon, A; Doherty, D T; Ekström, A; Fitzpatrick, C; Fransen, C; Georgiev, G; Gernhäuser, R; Hess, H; Iwanicki, J; Jenkins, D G; Larsen, A C; Ljungvall, J; Lutter, R; Marley, P; Moschner, K; Napiorkowski, P J; Pakarinen, J; Petts, A; Reiter, P; Renstrøm, T; Seidlitz, M; Siebeck, B; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Vermeulen, M; Voulot, D; Warr, N; Wenander, F; Wiens, A; De Witte, H; Wrzosek-Lipska, K

    2016-01-15

    Neutron-rich {96,98}Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60. PMID:26824536

  19. 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.

  20. Direct Lifetime Measurements of the Excited States in (72)Ni.

    PubMed

    Kolos, K; Miller, D; Grzywacz, R; Iwasaki, H; Al-Shudifat, M; Bazin, D; Bingham, C R; Braunroth, T; Cerizza, G; Gade, A; Lemasson, A; Liddick, S N; Madurga, M; Morse, C; Portillo, M; Rajabali, M M; Recchia, F; Riedinger, L L; Voss, P; Walters, W B; Weisshaar, D; Whitmore, K; Wimmer, K; Tostevin, J A

    2016-03-25

    The lifetimes of the first excited 2^{+} and 4^{+} states in ^{72}Ni were measured at the National Superconducting Cyclotron Laboratory with the recoil-distance Doppler-shift method, a model-independent probe to obtain the reduced transition probability. Excited states in ^{72}Ni were populated by the one-proton knockout reaction of an intermediate energy ^{73}Cu beam. γ-ray-recoil coincidences were detected with the γ-ray tracking array GRETINA and the S800 spectrograph. Our results provide evidence of enhanced transition probability B(E2;2^{+}→0^{+}) as compared to ^{68}Ni, but do not confirm the trend of large B(E2) values reported in the neighboring isotope ^{70}Ni obtained from Coulomb excitation measurement. The results are compared to shell model calculations. The lifetime obtained for the excited 4_{1}^{+} state is consistent with models showing decay of a seniority ν=4, 4^{+} state, which is consistent with the disappearance of the 8^{+} isomer in ^{72}Ni. PMID:27058074

  1. Direct Lifetime Measurements of the Excited States in 72Ni

    NASA Astrophysics Data System (ADS)

    Kolos, K.; Miller, D.; Grzywacz, R.; Iwasaki, H.; Al-Shudifat, M.; Bazin, D.; Bingham, C. R.; Braunroth, T.; Cerizza, G.; Gade, A.; Lemasson, A.; Liddick, S. N.; Madurga, M.; Morse, C.; Portillo, M.; Rajabali, M. M.; Recchia, F.; Riedinger, L. L.; Voss, P.; Walters, W. B.; Weisshaar, D.; Whitmore, K.; Wimmer, K.; Tostevin, J. A.

    2016-03-01

    The lifetimes of the first excited 2+ and 4+ states in 72>Ni were measured at the National Superconducting Cyclotron Laboratory with the recoil-distance Doppler-shift method, a model-independent probe to obtain the reduced transition probability. Excited states in 72Ni were populated by the one-proton knockout reaction of an intermediate energy 73Cu beam. γ -ray-recoil coincidences were detected with the γ -ray tracking array GRETINA and the S800 spectrograph. Our results provide evidence of enhanced transition probability B (E 2 ;2+→0+) as compared to 68Ni, but do not confirm the trend of large B (E 2 ) values reported in the neighboring isotope 70Ni obtained from Coulomb excitation measurement. The results are compared to shell model calculations. The lifetime obtained for the excited 41+ state is consistent with models showing decay of a seniority ν =4 , 4+ state, which is consistent with the disappearance of the 8+ isomer in 72Ni.

  2. Isotopic dependence of the cross section for the induced fission of heavy nuclei

    SciTech Connect

    Bolgova, O. N.; Adamian, G. G.; Antonenko, N. V.; Zubov, A. S.; Ivanova, S. P.; Scheid, W.

    2009-06-15

    The cross sections for the induced fission of {sup 211-223}Ra, {sup 203-211}Rn, and {sup 221-231}Th nuclei undergoing peripheral collisions with {sup 208}Pb nuclei are calculated on the basis of the statistical model. The role of the N = 126 neutron shell is studied. The level density in excited nuclei is determined within the Fermi gas model and a model that takes into account the collective enhancement of the level density. The inclusion of a particle-hole excitation in addition to a collective Coulomb excitation makes it possible to obtain a satisfactory description of experimental cross sections for the fission of radium isotopes. The calculated ratios of the cross sections for the induced fission of {sup 236}U ({sup 237}U) and {sup 238}U ({sup 239}U) nuclei agree with experimental data.

  3. Attractive Coulomb interaction of two-dimensional Rydberg excitons

    NASA Astrophysics Data System (ADS)

    Shahnazaryan, V.; Shelykh, I. A.; Kyriienko, O.

    2016-06-01

    We analyze theoretically the Coulomb scattering processes of highly excited excitons in the direct-band-gap semiconductor quantum wells. We find that contrary to the interaction of ground-state excitons, the electron and hole exchange interaction between excited excitons has an attractive character both for s - and p -type two-dimensional (2D) excitons. Moreover, we show that similar to the three-dimensional highly excited excitons, the direct interaction of 2D Rydberg excitons exhibits van der Waals-type long-range interaction. The results predict the linear growth of the absolute value of exchange interaction strength with an exciton principal quantum number and point the way towards enhancement of optical nonlinearity in 2D excitonic systems.

  4. Isotope separation using metallic vapor lasers

    NASA Technical Reports Server (NTRS)

    Russell, G. R.; Chen, C. J.; Harstad, K. G. (Inventor)

    1977-01-01

    The isotope U235 is separated from a gasified isotope mixture of U235 and U238 by selectively exciting the former from the ground state utilizing resonant absorption of radiation from precisely tuned lasers. The excited isotope is then selectively ionized by electron bombardment. It then is separated from the remaining isotope mixture by electromagnetic separation.

  5. 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

  6. 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.

  7. 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.

  8. Revealing the structural nature of the Cd isotopes

    NASA Astrophysics Data System (ADS)

    Garrett, P. E.; Diaz Varela, A.; Green, K. L.; Jamieson, D. S.; Jigmeddorj, B.; Wood, J. L.; Yates, S. W.

    2015-10-01

    The even-even Cd isotopes have provided fertile ground for the investigation of collectivity in nuclei. Soon after the development of the Bohr model, the stable Cd isotopes were identified as nearly harmonic vibrators based on their excitation energy patterns. The measurements of enhanced B (E 2) values appeared to support this interpretation. Shape co-existing rotational-like intruder bands were discovered, and mixing between the configurations was invoked to explain the deviation of the decay pattern of multiphonon vibrational states. Very recently, a detailed analysis of the low-lying levels of 110Cd combining results of the (n ,n' γ) reaction and high-statistics β decay, provided strong evidence that the mixing between configurations is weak, except for the ground-state band and ``Kπ =0+ '' intruder band. The analysis of the levels in 110Cd has now been extended to 3 MeV, and combined with data for 112Cd and previous Coulomb excitation data for 114Cd, enables a detailed map of the E 2 collectivity in these nuclei, demanding a complete re-interpretation of the structure of the stable Cd isotopes.

  9. Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

    NASA Astrophysics Data System (ADS)

    Grabert, Hermann

    2015-12-01

    The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

  10. 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.

  11. Attempt to produce the isotopes of element 108 in the fusion reaction {sup 136}Xe+{sup 136}Xe

    SciTech Connect

    Oganessian, Yu. Ts.; Dmitriev, S. N.; Yeremin, A. V.; Aksenov, N. V.; Bozhikov, G. A.; Chepigin, V. I.; Chelnokov, M. L.; Lebedev, V. Ya.; Malyshev, O. N.; Petrushkin, O. V.; Shishkin, S. V.; Svirikhin, A. I.; Tereshatov, E. E.; Vostokin, G. K.

    2009-02-15

    A setup of the experiment on the production of the isotopes with Z=108 in the fusion reaction {sup 136}Xe+{sup 136}Xe and the obtained results are presented. At the excitation energy 0{<=}E{sub x}{<=}30 MeV of the {sup 272}Hs* compound nucleus the upper limit of the cross section for evaporation residues {sigma}{sub (1-3)n}{<=}4 pb has been measured. The experimental results together with the data from asymmetric reactions point to a strong limitation of the Hs compound nucleus formation with increasing Coulomb forces in the entrance channel of the reaction.

  12. Experimental separation of virtual photon exchange and electron transfer in interatomic coulombic decay of neon dimers.

    PubMed

    Jahnke, T; Czasch, A; Schöffler, M; Schössler, S; Käsz, M; Titze, J; Kreidi, K; Grisenti, R E; Staudte, A; Jagutzki, O; Schmidt, L Ph H; Weber, Th; Schmidt-Böcking, H; Ueda, K; Dörner, R

    2007-10-12

    We investigate the interatomic Coulombic decay (ICD) of neon dimers following photoionization with simultaneous excitation of the ionized atom (shakeup) in a multiparticle coincidence experiment. We find that, depending on the parity of the excited state, which determines whether ICD takes place via virtual dipole photon emission or overlap of the wave functions, the decay happens at different internuclear distances, illustrating that nuclear dynamics heavily influence the electronic decay in the neon dimer. PMID:17995162

  13. Triplet excitations in graphene-based systems

    NASA Astrophysics Data System (ADS)

    Posvyanskiy, V.; Arnarson, L.; Hedegård, P.

    2015-02-01

    In this paper we investigate the excitations in a single graphene layer and in a single-walled carbon nanotube, i.e. the spectrum of magnetic excitations is calculated. In the absence of interactions in these systems there is a unique gap in the electron-hole continuum. We show that in the presence of Coulomb correlations bound states, magnons, appear in this forbidden region. The Coulomb interaction is examined in the context of the Pariser-Parr-Pople (PPP) model which takes into account the long-range nature of the interaction. The energy of the new bound states depends on the strength of the Coulomb forces. The calculations are performed for arbitrary electron-hole (e\\text-h) momentum q . In the end, this work finally settles the discussion sabout the existence of triplet excitations in graphene which has been lasting for a decade in the literature.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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)

  20. 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

  1. Laser isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Boyer, Keith; Greiner, Norman R.

    1988-01-01

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  2. Photochemical isotope separation

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1987-01-01

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  3. Photochemical isotope separation

    DOEpatents

    Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

    1987-04-28

    A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

  4. Laser isotope separation

    DOEpatents

    Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.

    1975-11-26

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  5. Measurement of proton capture cross sections relevant to rp process with Coulomb dissociation

    SciTech Connect

    Togano, Y.

    2010-08-12

    We have studied proton capture reactions on unstable proton-rich nuclei relevant to rapid proton-capture (rp) process using a Coulomb dissociation method. Using this method, three stellar reactions, {sup 22}Mg(p, {gamma}){sup 23}Al, {sup 26}Si(p, {gamma}){sup 27}P, and {sup 30}S(p, {gamma}){sup 31}Cl were studied at RIKEN Nishina Center. The radiative widths of the first excited state in {sup 23}Al and {sup 27}P, which are relevant to the stellar reactions, were obtained. We discuss the details of the Coulomb dissociation the astrophysical implications obtained from our studies.

  6. 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.

  7. 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

  8. 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.

  9. Nucleon pairing in Sn isotopes

    NASA Astrophysics Data System (ADS)

    Imasheva, L.; Ishkhanov, B.; Stepanov, M.; Tretyakova, T.

    2016-01-01

    The systematics of excited states in Sn isotopes are discussed on basis of pairing interaction in nuclei. Nucleon paring leads to formation of excited states multiplets. The estimation of multiplet splitting based on experimental nuclear masses allows one to calculate the position of excited states with different seniority in δ-approximation. The wide systematics of the spectra of Sn isotopes gives a possibility to check the pairing interaction for different subshells and consider the multiplets of excited states in the neutron-rich isotopes far from stability.

  10. 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 $R(x,Q^2)$.

  11. 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.

  12. Method for separating boron isotopes

    DOEpatents

    Rockwood, Stephen D.

    1978-01-01

    A method of separating boron isotopes .sup.10 B and .sup.11 B by laser-induced selective excitation and photodissociation of BCl.sub.3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub.3, thus effecting the desired separation of the boron isotopes.

  13. 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.

  14. Interatomic and intermolecular Coulombic decay: the coming of age story

    NASA Astrophysics Data System (ADS)

    Jahnke, T.

    2015-04-01

    In pioneering work by Cederbaum et al an excitation mechanism was proposed that occurs only in loosely bound matter (Cederbaum et al 1997 Phys. Rev. Lett. 79 4778): it turned out, that (in particular) in cases where a local Auger decay is energetically forbidden, an excited atom or molecule is able to decay in a scheme which was termed ‘interatomic Coulombic decay’ (or ‘intermolecular Coulombic decay’) (ICD). As ICD occurs, the excitation energy is released by transferring it to an atomic or molecular neighbor of the initially excited particle. As a consequence the neighboring atom or molecule is ionized as it receives the energy. A few years later the existence of ICD was confirmed experimentally (Marburger et al 2003 Phys. Rev. Lett. 90 203401; Jahnke et al 2004 Phys. Rev. Lett. 93 163401; Öhrwall et al 2004 Phys. Rev. Lett. 93 173401) by different techniques. Since this time it has been found that ICD is not (as initially suspected) an exotic feature of van der Waals or hydrogen bonded systems, but that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications. It was even demonstrated, that ICD can become more efficient than a local Auger decay in some system. This review will concentrate on recent experimental investigations on ICD. It will briefly introduce the phenomenon and give a short summary of the ‘early years’ of ICD (a detailed view on this episode of investigations can be found in the review article by U Hergenhahn with the same title (Hergenhahn 2011 J. Electron Spectrosc. Relat. Phenom. 184 78)). More recent articles will be presented that investigate the relevance of ICD in biological systems and possible radiation damage of such systems due to ICD. The occurrence of ICD and ICD-like processes after different excitation schemes and in different systems is covered in the middle section: in that context the helium dimer (He2

  15. Excited state mass spectra of Λc+ baryon

    NASA Astrophysics Data System (ADS)

    Shah, Zalak; Thakkar, Kaushal; Rai, Ajay Kumar; Vinodkumar, P. C.

    2016-05-01

    The radial and orbital excited state masses of singly charmed Λc+ baryon is calculated using the Hypercentral Constituent Quark Model (hCQM). The first order correction is applied to the confinement coulomb plus power potential. The ground and excited state masses for JP=3/2+ are calculated. Our results are in good agreement with experimental and other theoretical predictions.

  16. 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.

  17. 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

  18. Interatomic Coulombic decay widths of helium trimer: Ab initio calculations

    SciTech Connect

    Kolorenč, Přemysl; Sisourat, Nicolas

    2015-12-14

    We report on an extensive study of interatomic Coulombic decay (ICD) widths in helium trimer computed using a fully ab initio method based on the Fano theory of resonances. Algebraic diagrammatic construction for one-particle Green’s function is utilized for the solution of the many-electron problem. An advanced and universal approach to partitioning of the configuration space into discrete states and continuum subspaces is described and employed. Total decay widths are presented for all ICD-active states of the trimer characterized by one-site ionization and additional excitation of an electron into the second shell. Selected partial decay widths are analyzed in detail, showing how three-body effects can qualitatively change the character of certain relaxation transitions. Previously unreported type of three-electron decay processes is identified in one class of the metastable states.

  19. Interatomic Coulombic decay widths of helium trimer: Ab initio calculations.

    PubMed

    Kolorenč, Přemysl; Sisourat, Nicolas

    2015-12-14

    We report on an extensive study of interatomic Coulombic decay (ICD) widths in helium trimer computed using a fully ab initio method based on the Fano theory of resonances. Algebraic diagrammatic construction for one-particle Green's function is utilized for the solution of the many-electron problem. An advanced and universal approach to partitioning of the configuration space into discrete states and continuum subspaces is described and employed. Total decay widths are presented for all ICD-active states of the trimer characterized by one-site ionization and additional excitation of an electron into the second shell. Selected partial decay widths are analyzed in detail, showing how three-body effects can qualitatively change the character of certain relaxation transitions. Previously unreported type of three-electron decay processes is identified in one class of the metastable states. PMID:26671378

  20. Influence of Coulomb screening on lateral lasing in VECSELs.

    PubMed

    Wang, Chengao; Malloy, Kevin; Sheik-Bahae, Mansoor

    2015-12-14

    Parasitic lateral lasing in certain optically pumped semiconductor disc lasers drains the gain of the vertical mode and thus causes power scaling degradation and premature rollover in surface emitting operation. We have observed this effect in both multiple quantum wells (MQW) (GaInAs/GaAs) and double heterostructures (DHS) (GaInP/GaAs/GaInP) under pulsed excitation even when the gain chip lateral dimensions are much larger than the diameter of the pump laser. Lateral lasing occurs persistently between cleaved facets at a band-tail wavelength much longer than the peak of the gain. We show that the effect of bandgap renormalization due to Coulomb screening explains this phenomena. Exploiting the simple analytical plasma theory of bulk semiconductors (Banyai & Koch, 1986), we can account for such an effect in double heterostructures. PMID:26699044

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Observation of intracluster Coulombic decay of Rydberg-like states triggered by intense near-infrared pulses

    NASA Astrophysics Data System (ADS)

    Schütte, Bernd; Arbeiter, Mathias; Fennel, Thomas; Jabbari, Ghazal; Gokhberg, Kirill; Kuleff, Alexander I.; Vrakking, Marc J. J.; Rouzée, Arnaud

    2015-05-01

    Interatomic Coulombic decay (ICD) describes a process, where an excited atom relaxes by transferring its energy to an atom in the environment that gets ionized. So far, ICD has been observed following XUV ionization or excitation of clusters. Here we present novel results of an intracluster Coulombic decay mechanism induced by intense NIR pulses and following Rydberg atom formation in the generated nanoplasma. When a highly-excited Rydberg atom relaxes to its ground state by transferring its excess energy to a weakly bound electron in the environment, electrons with kinetic energies close to the atomic ionization potential are emitted. We show evidence for such an intracluster Coulombic decay process that leaves clear signatures in the electron kinetic energy spectra. ICD is time-resolved in a pump-probe experiment, where a weak probe pulse depopulates the excited states, leading to a quenching of the ICD signal. We find a decay time of 87 ps, which is siginificantly longer than for previous ICD observations, where inner-shell holes were created by XUV pulses. Intracluster Coulombic decay is found to be a generic process that takes places in atomic and molecular clusters and at different wavelengths. It may play an important role in biological systems and in astronomical plasmas. Previous affiliation: Max-Born-Institut, Berlin, Germany.

  7. 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.

  8. 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.

  9. Measurement of excitation functions in the reactions 197Au(11C, xn)208-xAt using a radioactive 11C beam

    PubMed

    Joosten; Powell; Guo; Haustein; Larimer; McMahan; Norman; O'Neil; Rowe; VanBrocklin; Wutte; Xu; Cerny

    2000-05-29

    A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) and (p,alpha) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, 197Au(11C,xn)208-xAt excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of 11C with intensities up to (1-2)x10(8) ions/sec on target. The results of this experiment are compared to measurements of 197Au(12C, xn)209-xAt excitation functions. PMID:10990868

  10. Cryogenic exciter

    SciTech Connect

    Bray, James William; Garces, Luis Jose

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  11. 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.

  12. 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.

  13. 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

  14. 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).

  15. 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)

  16. 18Ne Excited States Two-Proton Decay

    NASA Astrophysics Data System (ADS)

    de Napoli, M.; Rapisarda, E.; Raciti, G.; Cardella, G.; Amorini, F.; Giacoppo, F.; Sfienti, C.

    2008-04-01

    Two-proton radioactivity studies have been performed on excited states of 18Ne produced by 20Ne fragmentation at the FRS of the Laboratori Nazionali del Sud and excited via Coulomb excitation on a 209Pb target. The 18Ne levels decay has been studied by complete kinematical reconstruction. In spite of the low statistic, the energy and angular correlations of the emitted proton pairs indicate the presence of 2He emission toghether with the democratic decay.

  17. Dynamic polarizability and electric multipolar transitions in two electron atoms under exponential cosine screened coulomb potential

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Supriya K.; Modesto-Costa, Lucas; Mukherjee, Prasanta K.

    2016-05-01

    Detailed investigations on the frequency dependent polarizabilities, transition energies, oscillator strengths, and transition probabilities of two electron systems He, B e2 +, C4 + , and O6 + under electric dipolar (E1) and quadrupolar (E2) excitations have been performed using exponential cosine screened coulomb potential with a view to understand the structural behaviour of such systems due to external confinement produced by plasma environment. Time dependent coupled Hartree-Fock theory within a variational framework has been adopted for studying the first three low lying excited states 1 s2:1Se→1 s n p :1Po (n = 2, 3, 4) and 1 s n d :1De (n = 3, 4, 5) under such excitations. Quantitatively, the effect of confinement produced by the external plasma has been taken care of by considering the change in atomic potential through plasma screening, directly related to the coupling strength of the plasma with the atomic charge cloud. With increased plasma screening, a gradual destabilisation of the energy levels with subsequent reduction of the ionization potential and number of excited states has been observed. Behavioral pattern of the frequency dependent polarizabilities, excitation energies, oscillator strengths, and transition probabilities under systematic increase of the screening has been investigated. Results have been compared thoroughly with those available for free systems and under confinement by exponential cosine screened and screened Coulomb potential.

  18. Excitation of Er{sup 3+} ions in SiO{sub 2} with Si nanocrystals

    SciTech Connect

    Prokofiev, A. A. Moskalenko, A. S.; Yassievich, I. N.

    2008-08-15

    Probabilities of excitation of erbium ions via Coulomb interaction with carriers localized in silicon nanocrystals embedded in SiO{sub 2}, in recombination and intraband relaxation of these carriers, have been calculated.

  19. 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

  20. 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.

  1. Coulomb-interaction effects on the electronic structure of radially polarized excitons in nanorings

    NASA Astrophysics Data System (ADS)

    Barticevic, Z.; Pacheco, M.; Simonin, J.; Proetto, C. R.

    2006-04-01

    The electronic structure of radially polarized excitons in structured nanorings is analyzed, with emphasis in the ground-state properties and their dependence under applied magnetic fields perpendicular to the ring plane. The electron-hole Coulomb attraction has been treated rigorously, through numerical diagonalization of the full exciton Hamiltonian in the noninteracting electron-hole pairs basis. Depending on the relative weight of the kinetic energy and Coulomb contributions, the ground-state of polarized excitons has “extended” or “localized” features. In the first case, corresponding to small rings dominated by the kinetic energy, the ground-state shows Aharonov-Bohm (AB) oscillations due to the individual orbits of the building particles of the exciton. In the localized regime, corresponding to large rings dominated by the Coulomb interaction, the only remaining AB oscillations are due to the magnetic flux trapped between the electron and hole orbits. This dependence of the exciton, a neutral excitation, on the flux difference confirms this feature as a signature of Coulomb dominated polarized excitons. Analytical approximations are provided in both regimes, which accurately reproduce the numerical results.

  2. Simultaneous analysis of matter radii, transition probabilities, and excitation energies of Mg isotopes by angular-momentum-projected configuration-mixing calculations

    NASA Astrophysics Data System (ADS)

    Shimada, Mitsuhiro; Watanabe, Shin; Tagami, Shingo; Matsumoto, Takuma; Shimizu, Yoshifumi R.; Yahiro, Masanobu

    2016-06-01

    We perform simultaneous analysis of (1) matter radii, (2) B (E 2 ;0+→2+) transition probabilities, and (3) excitation energies, E (2+) and E (4+) , for Mg-4024 by using the beyond-mean-field (BMF) framework with angular-momentum-projected configuration mixing with respect to the axially symmetric β2 deformation with infinitesimal cranking. The BMF calculations successfully reproduce all of the data for rm,B (E 2 ) , and E (2+) and E (4+) , indicating that it is quite useful for data analysis; particularly for low-lying states. We also discuss the absolute value of the deformation parameter β2 deduced from measured values of B (E 2 ) and rm. This framework makes it possible to investigate the effects of β2 deformation, the change in β2 due to restoration of rotational symmetry, β2 configuration mixing, and the inclusion of time-odd components by infinitesimal cranking. Under the assumption of axial deformation and parity conservation, we clarify which effect is important for each of the three measurements and propose the kinds of BMF calculations that are practical for each of the three kinds of observables.

  3. Isotope separation by laser means

    DOEpatents

    Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

    1982-06-15

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  4. Short-time dynamics of correlated quantum Coulomb systems

    NASA Astrophysics Data System (ADS)

    Bonitz, Michael

    2007-03-01

    Strong correlations in dense Coulomb systems are attracting increasing interest in many fields ranging from dense astrophysical plasmas, dusty plasmas and semiconductors to metal clusters and ultracold trapped ions [1]. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) and many-particle correlations such as Coulomb and Yukawa liquids and crystals. Of particular current interest is the response of these systems to short excitations generated e.g. by femtosecond laser pulses and giving rise to ultrafast relaxation processes and build up of binary correlations. The proper theoretical tool are non-Markovian quantum kinetic equations [1,2] which can be derived from Nonequilibrium Green's Functions (NEGF) and are now successfully solved numerically for dense plasmas and semiconductors [3], correlated electrons [4] and other many-body systems with moderate correlations [5]. This method is well suited to compute the nonlinear response to strong fields selfconsistently including many-body effects [6]. Finally, we discuss recent extensions of the NEGF-computations to the dynamics of strongly correlated Coulomb systems, such as single atoms and molecules [7] and electron and exciton Wigner crystals in quantum dots [8,9]. [1] H. Haug and A.-P. Jauho, Quantum Kinetics in Transport and Optics of Semiconductors, Springer 1996; M. Bonitz Quantum Kinetic Theory, Teubner, Stuttgart/Leipzig 1998; [2] Progress in Nonequilibrium Green's Functions III, M. Bonitz and A. Filinov (Eds.), J. Phys. Conf. Ser. vol. 35 (2006); [3] M. Bonitz et al. Journal of Physics: Condensed Matter 8, 6057 (1996); R. Binder, H.S. K"ohler, and M. Bonitz, Phys. Rev. B 55, 5110 (1997); [4] N.H. Kwong, and M. Bonitz, Phys. Rev. Lett. 84, 1768 (2000); [5] Introduction to Computational Methods for Many-Body Systems, M. Bonitz and D. Semkat (eds.), Rinton Press, Princeton (2006); [6] H. Haberland, M. Bonitz, and D. Kremp, Phys. Rev. E 64

  5. 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.

  6. 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.

  7. 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.

  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. 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

  10. 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.

  11. 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.

  12. 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.

  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. Interatomic Coulombic decay following photoionization of the helium dimer: observation of vibrational structure.

    PubMed

    Havermeier, T; Jahnke, T; Kreidi, K; Wallauer, R; Voss, S; Schöffler, M; Schössler, S; Foucar, L; Neumann, N; Titze, J; Sann, H; Kühnel, M; Voigtsberger, J; Morilla, J H; Schöllkopf, W; Schmidt-Böcking, H; Grisenti, R E; Dörner, R

    2010-04-01

    Using synchrotron radiation we simultaneously ionize and excite one helium atom of a helium dimer (He2) in a shakeup process. The populated states of the dimer ion [i.e., He(*+)(n = 2, 3) - He] are found to deexcite via interatomic Coulombic decay. This leads to the emission of a second electron from the neutral site and a subsequent Coulomb explosion. In this Letter we present a measurement of the momenta of fragments that are created during this reaction. The electron energy distribution and the kinetic energy release of the two He+ ions show pronounced oscillations which we attribute to the structure of the vibrational wave function of the dimer ion. PMID:20481883

  15. Ultrafast dynamics of Coulomb correlated excitons in GaAs quantum wells

    SciTech Connect

    Mycek, M.A. |

    1995-12-01

    The author measures the transient nonlinear optical response of room temperature excitons in gallium arsenide quantum wells via multi-wave mixing experiments. The dynamics of the resonantly excited excitons is directly reflected by the ultrafast decay of the induced nonlinear polarization, which radiates the detected multi-wave mixing signal. She characterizes this ultrafast coherent emission in both amplitude and phase, using time- and frequency-domain measurement techniques, to better understand the role of Coulomb correlation in these systems. To interpret the experimental results, the nonlinear optical response of a dense medium is calculated using a model including Coulomb interaction. She contributes three new elements to previous theoretical and experimental studies of these systems. First, surpassing traditional time-integrated measurements, she temporally resolves the amplitude of the ultrafast coherent emission. Second, in addition to measuring the third-order four-wave mixing signal, she also investigates the fifth-order six-wave mixing response. Third, she characterizes the ultrafast phase dynamics of the nonlinear emission using interferometric techniques with an unprecedented resolution of approximately 140 attoseconds. The author finds that effects arising from Coulomb correlation dominate the nonlinear optical response when the density of excitons falls below 3 {times} 10{sup 11} cm{sup {minus}2}, the saturation density. These signatures of Coulomb correlation are investigated for increasing excitation density to gradually screen the interactions and test the validity of the model for dense media. The results are found to be qualitatively consistent with both the predictions of the model and with numerical solutions to the semiconductor Bloch equations. Importantly, the results also indicate current experimental and theoretical limitations, which should be addressed in future research.

  16. 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.

  17. A nuclear physics program at the Rare Isotope Beams Accelerator Facility in Korea

    SciTech Connect

    Moon, Chang-Bum

    2014-04-15

    This paper outlines the new physics possibilities that fall within the field of nuclear structure and astrophysics based on experiments with radioactive ion beams at the future Rare Isotope Beams Accelerator facility in Korea. This ambitious multi-beam facility has both an Isotope Separation On Line (ISOL) and fragmentation capability to produce rare isotopes beams (RIBs) and will be capable of producing and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. The large dynamic range of reaccelerated RIBs will allow the optimization in each nuclear reaction case with respect to cross section and channel opening. The low energy RIBs around Coulomb barrier offer nuclear reactions such as elastic resonance scatterings, one or two particle transfers, Coulomb multiple-excitations, fusion-evaporations, and direct capture reactions for the study of the very neutron-rich and proton-rich nuclides. In contrast, the high energy RIBs produced by in-flight fragmentation with reaccelerated ions from the ISOL enable to explore the study of neutron drip lines in intermediate mass regions. The proposed studies aim at investigating the exotic nuclei near and beyond the nucleon drip lines, and to explore how nuclear many-body systems change in such extreme regions by addressing the following topics: the evolution of shell structure in areas of extreme proton to neutron imbalance; the study of the weak interaction in exotic decay schemes such as beta-delayed two-neutron or two-proton emission; the change of isospin symmetry in isobaric mirror nuclei at the drip lines; two protons or two neutrons radioactivity beyond the drip lines; the role of the continuum states including resonant states above the particle-decay threshold in exotic nuclei; and the effects of nuclear reaction rates triggered by the unbound proton-rich nuclei on nuclear astrophysical processes.

  18. Excitation functions for production of heavy actinides from interactions of /sup 40/Ca and /sup 48/Ca ions with /sup 248/Cm

    SciTech Connect

    Hoffman, D.C.; Fowler, M.M.; Daniels, W.R.; von Gunten, H.R.; Lee, D.; Moody, K.J.; Gregorich, K.; Welch, R.; Seaborg, G.T.; Bruechle, W.

    1985-05-01

    Excitation functions have been measured for production of isotopes of Bk through Fm in bombardments of /sup 248/Cm with 234- to 294-MeV /sup 40/Ca ions and with 239- to 318-MeV /sup 48/Ca ions. The maxima of the isotopic distributions for these elements occur at only 2 to 3 mass numbers larger for /sup 48/Ca than for /sup 40/Ca reactions. The shapes of the distributions and the half-widths of about 2.5 mass numbers are quite similar to those observed previously for reactions of /sup 16/O, /sup 18/O, /sup 20/Ne, and /sup 22/Ne with /sup 248/Cm. In general, the excitation functions for /sup 40/Ca show maxima near the Coulomb barrier while those for /sup 48/Ca are about 20 MeV above the barrier. The cross sections decrease rather slowly with increasing projectile energy over the energy range studied, indicating that the additional projectile energy is not manifested as excitation energy of these actinide products.

  19. Isotope separation apparatus and method

    DOEpatents

    Feldman, Barry J.

    1985-01-01

    The invention relates to an improved method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferably substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. Because the molecules in the beam occupy various degenerate energy levels, if the laser beam comprises chirped pulses comprising selected wavelengths, the laser beam will very efficiently excite substantially all unexcited molecules and will cause stimulated emission of substantially all excited molecules of a selected one of the isotopes in the beam which such pulses encounter. Excitation caused by first direction chirped pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning chirped pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement of essentially all the molecules containing the one isotope is accomplished by a large number of chirped pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam.

  20. 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

  1. Dissociation of molecular chlorine in a Coulomb explosion: Potential curves, bound states, and deviation from Coulombic behavior for Cln+2 (n=2,3,4,6,8,10)

    NASA Astrophysics Data System (ADS)

    Wright, J. S.; Dilabio, G. A.; Matusek, D. R.; Corkum, P. B.; Ivanov, M. Yu.; Ellert, Ch.; Buenker, R. J.; Alekseyev, A. B.; Hirsch, G.

    1999-06-01

    Highly charged molecular ions are generated in Coulomb explosion experiments involving multielectron dissociative ionization, but little is known about the precise mechanisms involved in their formation. To help improve the understanding of such experiments, potential energy curves are calculated in this paper for diatomic chlorine (Cl2) and its ions Cln+2, where n=1,2,3,4,6,8,10. Bound vibrational states are obtained in three low-lying electronic states for Cl2+2 and one state for Cl3+2. Vertical excitation energies are given for stepwise excitations up to Cl10+2. For all the ions examined there is a significant energy defect (Δ) from the corresponding Coulomb potential, in one case reaching magnitudes of over 20 eV. We analyze the origin of these energy defects in terms of residual chemical bonding, and discuss the contribution of strongly bonding configurations at short internuclear distance. Finally, we present a simple physical model which describes the qualitative behavior of Δ(R,Q).

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Lifetime measurement for the 21+ state in 140Sm and the onset of collectivity in neutron-deficient Sm isotopes

    NASA Astrophysics Data System (ADS)

    Bello Garrote, F. L.; Görgen, A.; Mierzejewski, J.; Mihai, C.; Delaroche, J. P.; Girod, M.; Libert, J.; Sahin, E.; Srebrny, J.; Abraham, T.; Eriksen, T. K.; Giacoppo, F.; Hagen, T. W.; Kisielinski, M.; Klintefjord, M.; Komorowska, M.; Kowalczyk, M.; Larsen, A. C.; Marchlewski, T.; Mitu, I. O.; Pascu, S.; Siem, S.; Stolarz, A.; Tornyi, T. G.

    2015-08-01

    Background: The chain of Sm isotopes exhibits a wide range of nuclear shapes and collective behavior. While the onset of deformation for N >82 has been well studied both experimentally and theoretically, fundamental data is lacking for some Sm isotopes with N <82 . Purpose: Electromagnetic transition rates represent a sensitive test of theoretical nuclear structure models. Lifetime measurements are furthermore complementary to Coulomb excitation experiments, and the two methods together can give access to spectroscopic quadrupole moments. Method: The lifetime of the 21+ state in 140Sm was measured with the recoil-distance Doppler shift technique using the reaction 124Te(20Ne,4 n )140Sm at 82 MeV. Theoretical calculations were performed based on a mapped collective Hamiltonian in five quadrupole coordinates (5DCH) and the Gogny D1S interaction. Results: The lifetime of the 21+ state in 140Sm was found to be 9.1(6) ps, corresponding to a B (E 2 ;21+→01+) value of 51(4) Weisskopf units. The theoretical calculations are in very good agreement with the experimental result. Conclusions: The B (E 2 ;21+→01+) value for 140Sm fits smoothly into the systematic trend for the chain of Sm isotopes. The new beyond-mean field calculations are able to correctly describe the onset of collectivity in the Sm isotopes below the N =82 shell closure for the first time.

  9. 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.

  10. Experiments on Structure and Trapping of Coulomb balls

    SciTech Connect

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

    2006-10-18

    This paper gives a survey of recent experiments on Coulomb balls. Starting with typical observations to introduce the Coulomb ball experiment and its diagnostic potential, their structural properties are discussed. Further, the trapping mechanism for the dust is quantified to allow for a systematic comparison of experiment and simulations. Finally, the presented results focus on the question how screening influences the structural properties and how Coulomb balls and other strongly coupled systems are related.

  11. Three-body quantum Coulomb problem: Analytic continuation

    NASA Astrophysics Data System (ADS)

    Turbiner, A. V.; Lopez Vieyra, J. C.; Olivares Pilón, H.

    2016-08-01

    The second (unphysical) critical charge in the three-body quantum Coulomb system of a nucleus of positive charge Z and mass mp, and two electrons, predicted by Stillinger has been calculated to be equal to ZB∞ = 0.904854 and ZBmp = 0.905138 for infinite and finite (proton) mass mp, respectively. It is shown that in both cases, the ground state energy E(Z) (analytically continued beyond the first critical charge Zc, for which the ionization energy vanishes, to ReZ excited, spin-singlet bound state of negative hydrogen ion H‑ is predicted to be at ‑0.51554 a.u. (‑0.51531 a.u. for the finite proton mass mp). The first critical charge Zc is found accurately for a finite proton mass mp in the Lagrange mesh method, Zcmp = 0.911069724655.

  12. Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots.

    PubMed

    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. PMID:27541473

  13. Separating Isotopes With Laser And Electron Beams

    NASA Technical Reports Server (NTRS)

    Trajmar, Sandor

    1989-01-01

    Need for second laser eliminated. In scheme for separation of isotopes, electrons of suitable kinetic energy ionize specific isotope excited by laser beam in magnetic field. Ionization by electron beams cheap and efficient in comparison to ionization by laser beams, and requires no special technical developments. Feasibility of new scheme demonstrated in selective ionization of Ba138, making possible separation of isotope from Ba isotopes of atomic weight 130, 132, 134, 135, 136, and 137.

  14. Improved Shell models for screened Coulomb balls

    NASA Astrophysics Data System (ADS)

    Bonitz, M.; Kaehlert, H.; Henning, C.; Baumgartner, H.; Filinov, A.

    2006-10-01

    Spherical Coulomb crystals in dusty plasmas [1] are well described by an isotropic Yukawa-type pair interaction and an external parabolic confinement as was shown by extensive molecular dynamics simulations [2]. A much simpler description is possible with analytical shell models which have been derived for Yukawas plasmas in [3,4]. Here we analyze improved Yukawa shell models which include correlations along the lines proposed for Coulomb crystals in [5]. The shell configurations are efficiently evaluated using a Monte Carlo procedure. [1] O. Arp, A. Piel and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] M. Bonitz, D. Block, O. Arp, V. Golunychiy, H. Baumgartner, P. Ludwig, A. Piel and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [3] H. Totsuji, C. Totsuji, T. Ogawa, and K. Tsuruta, Phys. Rev. E 71, 045401 (2005). [4] C. Henning, M. Bonitz, A. Piel, P. Ludwig, H. Baumgartner, V. Golubnichiy, and D. Block, submitted to Phys. Rev. E [5] W.D. Kraeft and M. Bonitz, J. Phys. Conf. Ser. 35, 94 (2006).

  15. 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.

  16. 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}

  17. Experimental Investigation of the Stellar Reaction 30S(p,γ)31Cl via Coulomb Dissociation

    NASA Astrophysics Data System (ADS)

    Togano, Y.; Motobayashi, T.; Aoi, N.; Baba, H.; Bishop, S.; Cai, X.; Doornenbal, P.; Fang, D.; Furukawa, T.; Ieki, K.; Iwasa, N.; Kawabata, T.; Kanno, S.; Kobayashi, N.; Kondo, Y.; Kuboki, T.; Kume, N.; Kurita, K.; Kurokawa, M.; Ma, Y. G.; Matsuo, Y.; Murakami, H.; Matsushita, M.; Nakamura, T.; Okada, K.; Ota, S.; Satou, Y.; Shimoura, S.; Shioda, R.; Tanaka, K. N.; Takeuchi, S.; Tian, W.; Wang, H.; Wang, J.; Yamada, K.; Yamada, Y.; Yoneda, K.

    2011-09-01

    Coulomb dissociation of the proton-rich nucleus 31Cl was studied experimentally using a 31Cl beam at 58 MeV/nucleon with a lead target. The relative energy spectrum of 30S+p system was obtained from the measured momentum vectors of the reaction products detected in coincidence by the invariant mass method. The first excited state in 31Cl was observed which is relevant to the resonant capture in the stellar 30S(p,γ)31Cl reaction. Discussion for another observed state is also given.

  18. Self-Consistent Monte Carlo Study of the Coulomb Interaction under Nano-Scale Device Structures

    NASA Astrophysics Data System (ADS)

    Sano, Nobuyuki

    2011-03-01

    It has been pointed that the Coulomb interaction between the electrons is expected to be of crucial importance to predict reliable device characteristics. In particular, the device performance is greatly degraded due to the plasmon excitation represented by dynamical potential fluctuations in high-doped source and drain regions by the channel electrons. We employ the self-consistent 3D Monte Carlo (MC) simulations, which could reproduce both the correct mobility under various electron concentrations and the collective plasma waves, to study the physical impact of dynamical potential fluctuations on device performance under the Double-gate MOSFETs. The average force experienced by an electron due to the Coulomb interaction inside the device is evaluated by performing the self-consistent MC simulations and the fixed-potential MC simulations without the Coulomb interaction. Also, the band-tailing associated with the local potential fluctuations in high-doped source region is quantitatively evaluated and it is found that the band-tailing becomes strongly dependent of position in real space even inside the uniform source region. This work was partially supported by Grants-in-Aid for Scientific Research B (No. 2160160) from the Ministry of Education, Culture, Sports, Science and Technology in Japan.

  19. 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

  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. Isotope separation apparatus and method

    DOEpatents

    Cotter, Theodore P.

    1982-12-28

    The invention relates to a method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferable substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. The laser beam comprises .pi.-pulses of a selected wavelength which excite unexcited molecules, or cause stimulated emission of excited molecules of one of the isotopes. Excitation caused by first direction .pi.-pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning .pi.-pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement is accomplished by a large number of .pi.-pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam.

  2. Isotopically engineered semiconductors

    NASA Astrophysics Data System (ADS)

    Haller, E. E.

    1995-04-01

    for homogeneous doping of floating zone Si with P, holds perhaps the biggest promises for isotopically controlled semiconductors and is discussed in some detail. Local vibrational modes of low-mass impurities are sensitive to the mass of the impurity as well as the masses of the host atoms neighboring the impurity. High-resolution infrared-absorption studies of O in Ge crystals of different isotopic composition demonstrate the extreme simplification in such spectra which is achieved by isotope control. Interdiffusion of GaAs and Ge isotope superlattices with 0.1-1 μm thick layers have been studied with secondary-ion-mass spectroscopy. This kind of internal diffusion avoids the problems with surface effects and can produce accurate data without the need for radioactive tracers. The review closes with an outlook on the exciting future possibilities offered through isotope control of a wide range of semiconductor materials.

  3. Spherical Calogero model with oscillator/Coulomb potential: Quantum case

    NASA Astrophysics Data System (ADS)

    Correa, Francisco; Hakobyan, Tigran; Lechtenfeld, Olaf; Nersessian, Armen

    2016-06-01

    We consider the quantum mechanics of Calogero models in an oscillator or Coulomb potential on the N -dimensional sphere. Their Hamiltonians are obtained by an appropriate Dunkl deformation of the oscillator/Coulomb system on the sphere and its restriction to (Coxeter reflection) symmetric wave functions. By the same method we also find the symmetry generators and compute their algebras.

  4. Spherical Calogero model with oscillator/Coulomb potential: Classical case

    NASA Astrophysics Data System (ADS)

    Correa, Francisco; Hakobyan, Tigran; Lechtenfeld, Olaf; Nersessian, Armen

    2016-06-01

    We construct the Hamiltonians and symmetry generators of Calogero-oscillator and Calogero-Coulomb models on the N -dimensional sphere within the matrix-model reduction approach. Our method also produces the integrable Calogero-Coulomb-Stark model on the sphere and proves the integrability of the spin extensions of all these systems.

  5. Known-to-Unknown Approach to Teach about Coulomb's Law

    ERIC Educational Resources Information Center

    Thamburaj, P. K.

    2007-01-01

    Analogies from life experiences help students understand various relationships presented in an introductory chemistry course. Coulomb's law is a complex relationship encountered in introductory general chemistry. A proper understanding of the relationships between the quantities involved in Coulomb's law is necessary in order for students to…

  6. 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.

  7. Coulomb blockade of spin-dependent shuttling

    NASA Astrophysics Data System (ADS)

    Park, Hee Chul; Kadigrobov, Anatoli M.; Shekhter, Robert I.; Jonson, M.

    2013-12-01

    We show that nanomechanical shuttling of single electrons may enable qualitatively new functionality if spin-polarized electrons are injected into a nanoelectromechanical single-electron tunneling (NEM-SET) device. This is due to the combined effects of spin-dependent electron tunneling and Coulomb blockade of tunneling, which are phenomena that occur in certain magnetic NEM-SET devices. Two effects are predicted to occur in such structures. The first is a reentrant shuttle instability, by which we mean the sequential appearance, disappearance and again the appearance of a shuttle instability as the driving voltage is increased (or the mechanical dissipation is diminished). The second effect is an enhanced spin polarization of the nanomechanically assisted current flow.

  8. Ion Coulomb Crystals and Their Applications

    NASA Astrophysics Data System (ADS)

    Drewsen, Michael

    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 in the past two decades. While this document lacks figures and many specific references, it is the hope, not 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. A fully referenced journal article of essentially the same text can be found in Physica B 460, 105 (2015) [1].

  9. The ghost propagator in Coulomb gauge

    SciTech Connect

    Watson, P.; Reinhardt, H.

    2011-05-23

    We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until 'forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

  10. Theoretical description of Coulomb balls: Fluid phase

    SciTech Connect

    Wrighton, J.; Dufty, J. W.; Kaehlert, H.; Bonitz, M.

    2009-12-15

    A theoretical description for the radial density profile of a finite number of identical charged particles confined in a harmonic trap is developed for application over a wide range of Coulomb coupling (or, equivalently, temperatures) and particle numbers. A simple mean-field approximation neglecting correlations yields a density profile which is monotonically decreasing with radius for all temperatures, in contrast to molecular dynamics simulations and experiments showing shell structure at lower temperatures. A more complete theoretical description including charge correlations is developed here by an extension of the hypernetted chain approximation, developed for bulk fluids, to the confined charges. The results reproduce all of the qualitative features observed in molecular dynamics simulations and experiments. These predictions are then tested quantitatively by comparison with benchmark Monte Carlo simulations. Quantitative accuracy of the theory is obtained by correcting the hypernetted chain approximation with a representation for the associated bridge functions.

  11. 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.

  12. Nuclear excitation by electronic transition of 235U

    DOE PAGESBeta

    Chodash, P. A.; Norman, E. B.; Burke, J. T.; Casperson, R. J.; Fisher, S. E.; Holliday, K. S.; Jeffries, J. R.; Wakeling, M. A.; Wilks, S. C.

    2016-03-11

    Here, nuclear excitation by electronic transition (NEET) is a rare nuclear excitation that can occur in isotopes containing a low-lying nuclear excited state. Over the past 40 yr, several experiments have attempted to measure NEET of 235U and those experiments have yielded conflicting results.

  13. First prediction of inter-Coulombic decay of C60 inner vacancies through the continuum of confined atoms

    NASA Astrophysics Data System (ADS)

    De, Ruma; Magrakvelidze, Maia; Madjet, Mohamed E.; Manson, Steven T.; Chakraborty, Himadri S.

    2016-06-01

    Considering the photoionization of Ar@{{{C}}}60 and Kr@{{{C}}}60 endofullerenes, the decay of {{{C}}}60 innershell excitations through the outershell continuum of the confined atom via the inter-Coulombic decay (ICD) pathway is detailed. Excitations to atom-{{{C}}}60 hybrid states, when these states exist, can induce coherence between ICD and electron-transfer mediated decay (ETMD). This should be the dominant above-threshold decay process for a variety of confined systems, and the strength of these resonances is such that they should be amenable for study by photoelectron spectroscopy.

  14. Analysis of 8Li(α,n)11B below the Coulomb barrier in the potential model

    NASA Astrophysics Data System (ADS)

    Rauscher, T.; Grün, K.; Krauss, H.; Oberhummer, H.; Kwasniewicz, E.

    1992-04-01

    The reaction 8Li(α,n)11B is of interest in inhomogeneous big bang nucleosynthesis. A distorted wave Born approximation calculation employing folding potentials is presented for energies below the Coulomb barrier. The recently observed resonance at about 540 keV center-of-mass energy can be reproduced. The astrophysical S factor is calculated for the ground-state transition as well as for the transitions to the first four excited states of 11B. The reaction rate is derived and compared to literature data. The inclusion of the excited states increases the rate by a factor of 1.5 compared to the ground-state transition.

  15. Isotopic Biogeochemistry

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  16. Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit

    NASA Astrophysics Data System (ADS)

    Gebremedhin, Daniel H.; Weatherford, Charles A.

    2014-05-01

    An efficient way of evolving a solution to an ordinary differential equation is presented. A finite element method is used where we expand in a convenient local basis set of functions that enforce both function and first derivative continuity across the boundaries of each element. We also implement an adaptive step-size choice for each element that is based on a Taylor series expansion. This algorithm is used to solve for the eigenpairs corresponding to the one-dimensional soft Coulomb potential, 1/√x2+β2 , which becomes numerically intractable (because of extreme stiffness) as the softening parameter (β) approaches zero. We are able to maintain near machine accuracy for β as low as β =10-8 using 16-digit precision calculations. Our numerical results provide insight into the controversial one-dimensional hydrogen atom, which is a limiting case of the soft Coulomb problem as β →0.

  17. Method for isotope enrichment by photoinduced chemiionization

    DOEpatents

    Dubrin, James W.

    1985-01-01

    Isotope enrichment, particularly .sup.235 U enrichment, is achieved by irradiating an isotopically mixed vapor feed with radiant energy at a wavelength or wavelengths chosen to selectively excite the species containing a desired isotope to a predetermined energy level. The vapor feed if simultaneously reacted with an atomic or molecular reactant species capable of preferentially transforming the excited species into an ionic product by a chemiionization reaction. The ionic product, enriched in the desired isotope, is electrostatically or electromagnetically extracted from the reaction system.

  18. Impact of nuclear dynamics on interatomic Coulombic decay in a He dimer

    SciTech Connect

    Sisourat, Nicolas; Kryzhevoi, Nikolai V.; Cederbaum, Lorenz S.; Kolorenc, Premysl; Scheit, Simona

    2010-11-15

    After simultaneous ionization and excitation of one helium atom within the giant weakly bound helium dimer, the excited ion can relax via interatomic Coulombic decay (ICD) and the excess energy is transferred to ionize the neighboring helium atom. We showed [Sisourat et al. Nature Phys. 6, 508 (2010)] that the distributions of the kinetic energy released by the two ions reflect the nodal structures of the ICD-involved vibrational wave functions. We also demonstrated that energy transfer via ICD between the two helium atoms can take place over more than 14 A. We report here a more detailed analysis of the ICD process and of the impact of the nuclear dynamics on the electronic decay. Nonadiabatic effects during the ICD process and the accuracy of the potential energy curve of helium dimer and of the computed decay rates are also investigated.

  19. Excited Delirium

    PubMed Central

    Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

    2011-01-01

    Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

  20. Excited baryons

    SciTech Connect

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  1. Heavy-ion reactions near the Coulomb barrier

    SciTech Connect

    Esbensen, H.; Rehm, K.E.; Jiang, C.L.

    1995-08-01

    Fusion reactions between different Kr and Ni isotopes were measured recently at ATLAS. We performed coupled-channels calculations and made comparisons to the measurements. Such calculations become increasingly difficult for heavy, soft nuclei due to strong couplings and the importance of higher-order, multi-step processes. The calculations were made possible by adopting the so-called rotating frame approximation, and they included one- and two-phonon excitations of the low-lying 2{sup +} and 3{sup -} states in both the projectile and the target. These calculations reproduced quite accurately the measured fusion cross sections for a beam of {sup 86}Kr. Some discrepancies remain for the much softer {sup 78}Kr nucleus; the calculations were clearly much more sensitive to higher-order processes in this case. In particular, it was important to implement the correct coupling strength and excitation energy for the soft, one- to two-phonon quadrupole transition in {sup 78}Kr, which differs significantly from the vibrational limit. This work was performed in collaboration with the experimentalists and was submitted for publication.

  2. 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.

  3. Search for intrinsic collective excitations in {sup 152}Sm

    SciTech Connect

    Kulp, W. D.; Wood, J. L.; Allmond, J. M.; Garrett, P. E.; Wu, C. Y.; Cline, D.; Hayes, A. B.; Hua, H.; Teng, R.; Bandyopadhyay, D.; Choudry, S. N.; McEllistrem, M. T.; McKay, C. J.; Orce, J. N.; Dashdorj, D.; Mynk, M. G.; Yates, S. W.

    2008-06-15

    The 685 keV excitation energy of the first excited 0{sup +} state in {sup 152}Sm makes it an attractive candidate to explore expected two-phonon excitations at low energy. Multiple-step Coulomb excitation and inelastic neutron scattering studies of {sup 152}Sm are used to probe the E2 collectivity of excited 0{sup +} states in this 'soft' nucleus and the results are compared with model predictions. No candidates for two-phonon K{sup {pi}}=0{sup +}quadrupole vibrational states are found. A 2{sup +},K=2 state with strong E2 decay to the first excited K{sup {pi}}=0{sup +} band and a probable 3{sup +} band member are established.

  4. 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

  5. Accelerated Monte Carlo Methods for Coulomb Collisions

    NASA Astrophysics Data System (ADS)

    Rosin, Mark; Ricketson, Lee; Dimits, Andris; Caflisch, Russel; Cohen, Bruce

    2014-03-01

    We present a new highly efficient multi-level Monte Carlo (MLMC) simulation algorithm for Coulomb collisions in a plasma. The scheme, initially developed and used successfully for applications in financial mathematics, is applied here to kinetic plasmas for the first time. The method is based on a Langevin treatment of the Landau-Fokker-Planck equation and has a rich history derived from the works of Einstein and Chandrasekhar. The MLMC scheme successfully reduces the computational cost of achieving an RMS error ɛ in the numerical solution to collisional plasma problems from (ɛ-3) - for the standard state-of-the-art Langevin and binary collision algorithms - to a theoretically optimal (ɛ-2) scaling, when used in conjunction with an underlying Milstein discretization to the Langevin equation. In the test case presented here, the method accelerates simulations by factors of up to 100. We summarize the scheme, present some tricks for improving its efficiency yet further, and discuss the method's range of applicability. Work performed for US DOE by LLNL under contract DE-AC52- 07NA27344 and by UCLA under grant DE-FG02-05ER25710.

  6. Spatio-temporal correlations in Coulomb clusters

    NASA Astrophysics Data System (ADS)

    Ghosal, Amit; Ash, Biswarup; Chakrabarti, Jaydeb

    Dynamical response of Coulomb-particles in nanoclusters are investigated at different temperatures characterizing their solid-like (Wigner molecule) and liquid-like behavior. The density correlations probe spatio-temporal relaxation, uncovering distinct behavior at multiple time scales in these systems. They show a stretched-Gaussian or stretched-exponential spatial decay at long times in circular and irregular traps. Interplay of confinement and long-range nature of interactions yields spatially correlated motion of the particles in string-like paths, leaving the system heterogeneous even at long times. While particles in a `solid' flow producing dynamic heterogeneities, their random motion in `liquid' defies central limit theorem. Distinguishing the two confinements, temperature dependent motional signatures serve as a criterion for the crossover between `solid' and `liquid'. The irregular Wigner molecule turns into a nearly homogeneous liquid over a much wider temperature window compared to the circular case. The temperature dependence of different relaxation time scales builds crucial insights. A phenomenological model, relating the unusual dynamics to the heterogeneous nature of the diffusivities in the system, captures much of the subtleties of our numerical simulations.

  7. Multilevel Monte Carlo simulation of Coulomb collisions

    DOE PAGESBeta

    Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; Caflisch, R. E.; Cohen, B. I.

    2014-05-29

    We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε , the computational cost of the method is O(ε–2) or (ε–2(lnε)2), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε–3) for direct simulation Monte Carlo or binary collision methods.more » We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10–5. Lastly, we discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.« less

  8. Multilevel Monte Carlo simulation of Coulomb collisions

    SciTech Connect

    Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; Caflisch, R. E.; Cohen, B. I.

    2014-05-29

    We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau–Fokker–Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ε , the computational cost of the method is O(ε–2) or (ε–2(lnε)2), depending on the underlying discretization, Milstein or Euler–Maruyama respectively. This is to be contrasted with a cost of O(ε–3) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ε=10–5. Lastly, we discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.

  9. 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.

  10. Coulomb Collision Algorithms for Particle Codes

    NASA Astrophysics Data System (ADS)

    Cohen, Bruce

    2006-04-01

    This paper surveys some of the particle code algorithms used to model Coulomb collisions in fully ionized plasmas, e.g., pair-wise operators such as the Takizuka-Abe^1 scheme and extensions^2, Langevin equation collision operators^3,4, and partially linearized gyrokinetic collisions operators for strongly magnetized plasmas.^5,6,7 Some recent experience is reported.^8 Issues such as physics completeness, accuracy, and comparative algorithm performance are highlighted. 1. T. Takizuka and H. Abe, J. Comput. Phys. 25, 205 (1977). 2. K. Nanbu, Phys. Rev. E 55, 4642 (1997). 3. M.E. Jones, et al., J. Comp. Phys. 123, 169 (1996). 4. W.M. Manheimer, M. Lampe, and G. Joyce, et al., J. Comp. Phys. 138, 565 (1997). 5. X.Q. Xu and M.N. Rosenbluth, Phys. Fluids B 3, 627 (1991). 6. A.M. Dimits and B.I. Cohen, Phys. Rev. E 49, 709 (1994). 7. Z. Lin, W. M. Tang, and W. W. Lee, Phys.Plasmas 2, 2975 (August 1995). 8. B.I. Cohen, et al., ``Effects of ion-ion collisions and inhomogeneity in two-dimensional kinetic ion simulations of stimulated Brillouin backscattering,'' accepted for publication in Phys. Plasmas (2006).

  11. 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.

  12. CNO cycle: ”Soft E1” mode of the 17Ne excitation in the 17Ne+γ → 15O+2p reaction

    NASA Astrophysics Data System (ADS)

    Parfenova, Yu L.; Grigorenko, L. V.; Egorova, I. A.; Shulgina, N. B.; Zhukov, M. V.

    2016-01-01

    The 15O(2p, γ)17Ne reaction is studied using the time-reversed reaction of the17Ne E1 Coulomb dissociation on lead target in the context of nuclear astrophysics. Looking for the relation between the data on the Coulomb excitation and the astrophysical 2p-capture rate, one faces problem to extract the Coulomb E1 strength function from the measured Coulex cross section. We use a number of phenomenological approaches to estimate influence of such processes as Coulomb-nuclear interference, populations of states with different Jπ, etc. We calculate the 17Ne+2p astrophysical capture rate and compare the results with different calculations.

  13. Isotopic yield in cold binary fission of even-even 244-258Cf isotopes

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Cyriac, Annu; Krishnan, Sreejith

    2016-05-01

    The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that for 244,246,248Cf isotopes highest yield is for the fragments with isotope of Pb (Z = 82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z = 80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z = 50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favored for Cf isotopes with mass number A ≤ 250 and symmetric splitting is favored for Cf isotopes with A > 252. In the case of Cf isotope with A = 252, there is an equal probability for asymmetric and symmetric splitting. The individual yields obtained for the cold fission of 252Cf isotope are compared with the experimental data taken from the γ- γ- γ coincidences technique using Gammasphere.

  14. Magnetic dipolar and quadrupolar transitions in two-electron atoms under exponential-cosine-screened Coulomb potential

    SciTech Connect

    Modesto-Costa, Lucas; Canuto, Sylvio; Mukherjee, Prasanta K.

    2015-03-15

    A detailed investigation of the magnetic dipolar and quadrupolar excitation energies and transition probabilities of helium isoelectronic He, Be{sup 2+}, C{sup 4+}, and O{sup 6+} have been performed under exponential cosine screened Coulomb potential generated in a plasma environment. The low-lying excited states 1s{sup 2}:{sup 1}S{sup e} → 1sns:{sup 3}S{sup e}{sub 0}, and 1snp:{sup 3}P{sup o}{sub 2} (n = 2, 3, 4, and 5) are considered. The variational time-dependent coupled Hartree-Fock scheme has been used. The effect of the confinement produced by the potential on the structural properties is investigated for increasing coupling strength of the plasma. It is noted that there is a gradual destabilization of the energy of the system with the reduction of the ionization potential and the number of excited states. The effect of the screening enhancement on the excitation energies and transition probabilities has also been investigated and the results compared with those available for the free systems and under the simple screened Coulomb potential.

  15. Coulomb Mediated Hybridization of Excitons in Coupled Quantum Dots

    NASA Astrophysics Data System (ADS)

    Ardelt, P.-L.; Gawarecki, K.; Müller, K.; Waeber, A. M.; Bechtold, A.; Oberhofer, K.; Daniels, J. M.; Klotz, F.; Bichler, M.; Kuhn, T.; Krenner, H. J.; Machnikowski, P.; Finley, J. J.

    2016-02-01

    We report Coulomb mediated hybridization of excitonic states in optically active InGaAs quantum dot molecules. By probing the optical response of an individual quantum dot molecule as a function of the static electric field applied along the molecular axis, we observe unexpected avoided level crossings that do not arise from the dominant single-particle tunnel coupling. We identify a new few-particle coupling mechanism stemming from Coulomb interactions between different neutral exciton states. Such Coulomb resonances hybridize the exciton wave function over four different electron and hole single-particle orbitals. Comparisons of experimental observations with microscopic eight-band k .p calculations taking into account a realistic quantum dot geometry show good agreement and reveal that the Coulomb resonances arise from broken symmetry in the artificial semiconductor molecule.

  16. 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.

  17. 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

  18. The generalized Coulomb interactions for relativistic scalar bosons

    NASA Astrophysics Data System (ADS)

    Zarrinkamar, S.; Panahi, H.; Rezaei, M.

    2016-07-01

    Approximate analytical solutions of Duffin-Kemmer-Petiau (DKP) equation are obtained for the truncated Coulomb, generalized Cornell, Richardson and Song-Lin potentials via the quasi-exact analytical ansatz approach.

  19. 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.

  20. Sexual excitement.

    PubMed

    Stoller, R J

    1976-08-01

    Sexual excitement depends on a scenario the person to be aroused has been writing since childhood. The story is an adventure, an autobiography disguised as fiction, in which the hero/heroine hides crucial intrapsychic conflicts, mysteries, screen memories of actual traumatic events and the resolution of these elements into a happy ending, best celebrated by orgasm. The function of the fantasy is to take these painful experiences and convert them to pleasure-triumph. In order to sharpen excitement-the vibration between the fear of original traumas repeating and the hope of a pleasurable conclusion this time-one introduces into the story elements of risk (approximations of the trauma) meant to prevent boredom and safety factors (sub-limnal signals to the storyteller that the risk are not truly dangerous). Sexual fantasy can be studied by means of a person's daydreams (including those chosen in magazines, books, plays, television, movies, and outright pornography), masturbatory behavior, object choice, foreplay, techniques of intercourse, or postcoital behavior. PMID:949223

  1. Investigation of ion capture in an electron beam ion trap charge-breeder for rare isotopes

    NASA Astrophysics Data System (ADS)

    Kittimanapun, Kritsada

    Charge breeding of rare isotope ions has become an important ingredient for providing reaccelerated rare isotope beams for science. At the National Superconducting Cyclotron Laboratory (NSCL), a reaccelerator, ReA, has been built that employs an advanced Electron Beam Ion Trap (EBIT) as a charge breeder. ReA will provide rare-isotope beams with energies of a few hundred keV/u up to tens of MeV/u to enable the study of properties of rare isotopes via low energy Coulomb excitation and transfer reactions, and to investigate nuclear reactions important for nuclear astrophysics. ReA consists of an EBIT charge breeder, a charge-over-mass selector, a room temperature radio-frequency quadrupole accelerator, and a superconducting radio-frequency linear accelerator. The EBIT charge breeder features a high-current electron gun, a long trap structure, and a hybrid superconducting magnet to reach both high acceptance for injected low-charge ions as well as high-electron beam current densities for fast charge breeding. In this work, continuous ion injection and capture in the EBIT have been investigated with a dedicated Monte-Carlo simulation code and in experimental studies. The Monte-Carlo code NEBIT considers the electron-impact ionization cross sections, space charge due to the electron beam current, ion dynamics, electric field from electrodes, and magnetic field from the superconducting magnet. Experiments were performed to study the capture efficiency as a function of injected ion beam current, electron beam current, trap size, and trap potential depth. The charge state evolution of trapped ions was studied, providing information about the effective current density of the electron beam inside the EBIT. An attempt was made to measure the effective space-charge potential of the electron beam by studying the dynamics of a beam injected and reflected inside the trap.

  2. Octupole strength in the neutron-rich calcium isotopes

    NASA Astrophysics Data System (ADS)

    Riley, L. A.; McPherson, D. M.; Agiorgousis, M. L.; Baugher, T. R.; Bazin, D.; Bowry, M.; Cottle, P. D.; DeVone, F. G.; Gade, A.; Glowacki, M. T.; Gregory, S. D.; Haldeman, E. B.; Kemper, K. W.; Lunderberg, E.; Noji, S.; Recchia, F.; Sadler, B. V.; Scott, M.; Weisshaar, D.; Zegers, R. G. T.

    2016-04-01

    Low-lying excited states of the neutron-rich calcium isotopes Ca-5248 have been studied via γ -ray spectroscopy following inverse-kinematics proton scattering on a liquid hydrogen target using the GRETINA γ -ray tracking array. The energies and strengths of the octupole states in these isotopes are remarkably constant, indicating that these states are dominated by proton excitations.

  3. A New Hybrid STEP/Coulomb model for Aftershock Forecasting

    NASA Astrophysics Data System (ADS)

    Steacy, S.; Jimenez, A.; Gerstenberger, M.

    2014-12-01

    Aftershock forecasting models tend to fall into two classes - purely statistical approaches based on clustering, b-value, and the Omori-Utsu law; and Coulomb rate-state models which relate the forecast increase in rate to the magnitude of the Coulomb stress change. Recently, hybrid models combining physical and statistical forecasts have begun to be developed, for example by Bach and Hainzl (2012) and Steacy et al. (2013). The latter approach combined Coulomb stress patterns with the STEP (short-term earthquake probability) model by redistributing expected rate from areas with decreased stress to regions where the stress had increased. The chosen 'Coulomb Redistribution Parameter' (CRP) was 0.93, based on California earthquakes, which meant that 93% of the total rate was expected to occur where the stress had increased. The model was tested against the Canterbury sequence and the main result was that the new model performed at least as well as, and often better than, STEP when tested against retrospective data but that STEP was generally better in pseudo-prospective tests that involved data actually available within the first 10 days of each event of interest. The authors suggested that the major reason for this discrepancy was uncertainty in the slip models and, particularly, in the geometries of the faults involved in each complex major event. Here we develop a variant of the STEP/Coulomb model in which the CRP varies based on the percentage of aftershocks that occur in the positively stressed areas during the forecast learning period. We find that this variant significantly outperforms both STEP and the previous hybrid model in almost all cases, even when the input Coulomb model is quite poor. Our results suggest that this approach might be more useful than Coulomb rate-state when the underlying slip model is not well constrained due to the dependence of that method on the magnitude of the Coulomb stress change.

  4. Diffusion and Coulomb separation of ions in dense matter.

    PubMed

    Beznogov, M V; Yakovlev, D G

    2013-10-18

    We analyze diffusion equations in strongly coupled Coulomb mixtures of ions in dense stellar matter. Strong coupling of ions in the presence of gravitational forces and electric fields (induced by plasma polarization in the presence of gravity) produces a specific diffusion current which can separate ions with the same A/Z (mass to charge number) ratios but different Z. This Coulomb separation of ions can be important for the evolution of white dwarfs and neutron stars. PMID:24182248

  5. Renormalization in Coulomb-gauge QCD within the Lagrangian formalism

    SciTech Connect

    Niegawa, A.

    2006-08-15

    We study renormalization of Coulomb-gauge QCD within the Lagrangian, second-order, formalism. We derive a Ward identity and the Zinn-Justin equation, and, with the help of the latter, we give a proof of algebraic renormalizability of the theory. Through diagrammatic analysis, we show that, in the strict Coulomb gauge, g{sup 2}D{sup 00} is invariant under renormalization. (D{sup 00} is the time-time component of the gluon propagator.)

  6. Diffusion and Coulomb Separation of Ions in Dense Matter

    NASA Astrophysics Data System (ADS)

    Beznogov, M. V.; Yakovlev, D. G.

    2013-10-01

    We analyze diffusion equations in strongly coupled Coulomb mixtures of ions in dense stellar matter. Strong coupling of ions in the presence of gravitational forces and electric fields (induced by plasma polarization in the presence of gravity) produces a specific diffusion current which can separate ions with the same A/Z (mass to charge number) ratios but different Z. This Coulomb separation of ions can be important for the evolution of white dwarfs and neutron stars.

  7. Coulomb's Law Modification in Nonlinear and in Noncommutative Electrodynamics

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Schmidt, Iván

    We study the lowest-order modifications of the static potential for Born-Infeld electrodynamics and for the θ-expanded version of the noncommutative U(1) gauge theory, within the framework of the gauge-invariant but path-dependent variables formalism. The calculation shows a long-range correction (1/r5-type) to the Coulomb potential in Born-Infeld electrodynamics. However, the Coulomb nature of the potential (to order e2) is preserved in noncommutative electrodynamics.

  8. Isotope separation by selective photodissociation of glyoxal

    DOEpatents

    Marling, John B.

    1976-01-01

    Dissociation products, mainly formaldehyde and carbon monoxide, enriched in a desired isotope of carbon, oxygen, or hydrogen are obtained by the selective photodissociation of glyoxal wherein glyoxal is subjected to electromagnetic radiation of a predetermined wavelength such that photon absorption excites and induces dissociation of only those molecules of glyoxal containing the desired isotope.

  9. Experimental study of the 15O(2p, γ)17Ne cross section by Coulomb Dissociation for the rp process

    NASA Astrophysics Data System (ADS)

    Marganiec, J.; Warners, F.; Aksouh, F.; Aksyutina, Y.; Alvarez Pol, H.; Aumann, T.; Beceiro, S.; Bertulani, C.; Boretzky, K.; Borge, M. J.; Chartier, M.; Chatillon, A.; Chulkov, L.; Cortina-Gil, D.; Egorova, I.; Emling, H.; Ershova, O.; Forssén, C.; Fraile, L. M.; Fynbo, H.; Galaviz, D.; Geissel, H.; Grigorenko, L.; Heil, M.; Hoffmann, D. H. H.; Hoffmann, J.; Johansson, H.; Jonson, B.; Karakoç, M.; Karagiannis, C.; Kiselev, O.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Langer, C.; Lantz, M.; Larsson, K.; Le Bleis, T.; Lemmon, R.; Litvinov, Yu A.; Mahata, K.; Müntz, C.; Nilsson, T.; Nociforo, C.; Nyman, G.; Ott, W.; Panin, V.; Parfenova, Yu; Paschalis, S.; Perea, A.; Plag, R.; Reifarth, R.; Richter, A.; Riisager, K.; Rodríguez Tajes, C.; Rossi, D.; Schrieder, G.; Shulgina, N.; Simon, H.; Stroth, J.; Sümmerer, K.; Taylor, J.; Tengblad, O.; Tengborn, E.; Weick, H.; Wiescher, M.; Wimmer, C.; Zhukov, M.

    2016-01-01

    The time-reversed reaction 15O(2p, γ)17Ne has been studied by the Coulomb dissociation technique. Secondary 17Ne ion beams at 500 AMeV have been produced by fragmentation reactions of 20Ne in a beryllium production target and dissociated on a secondary Pb target. The incoming beam and the reaction products have been identified with the kinematically complete LAND-R3B experimental setup at GSI. The excitation energy prior to decay has been reconstructed by using the invariant-mass method. The preliminary differential and integral Coulomb Dissociation cross sections (σCoul) have been calculated, which provide a photoabsorption (σphoto) and a radiative capture cross section (σcap). Additionally, important information about the nuclear structure of the 17Ne nucleus will be obtained. The analysis is in progress.

  10. Aftershock triggering by complete Coulomb stress changes

    USGS Publications Warehouse

    Kilb, Debi; Gomberg, J.; Bodin, P.

    2002-01-01

    We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (??CFS(t)) that this earthquake generated. At close distances the time-varying "dynamic" portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent "static" portion (??CFS) depends only on the final coseismic displacement. ??CFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ??CFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ??CFS(t) can alter the failure rate only by the latter means. We calculate both ??CFS and the maximum positive value of ??CFS(t) (peak ??CFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ??CFS and peak ??CFS(t) and find agreement for both models. However, rupture directivity, which does not affect ??CFS, creates larger peak ??CFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ??CFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.

  11. 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.

  12. 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.

  13. 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

  14. The One-Dimensional Soft-Coulomb Problem and the Hard-Coulomb Limit

    NASA Astrophysics Data System (ADS)

    Weatherford, Charles; Gebremedhin, Daniel

    2014-05-01

    A new and efficient way of evolving a solution to an ordinary differential equation is presented. A finite element method is used where we expand in a convenient local basis set of functions that enforce both function and first derivative continuity across the boundary. We also, for the first time, implement an adaptive step size choice for each element that is based on a Taylor series expansion. This algorithm is used to solve for the eigenpairs corresponding to the one-dimensional soft Coulomb potential, 1 /√{x2 +β2 } , which becomes numerically intractable as the softening parameter (β) approaches zero. We are able to maintain near machine accuracy for β as low as β =10-8 using 16 digit precision calculations. Our numerical results provide a new insight into the controversial one dimensional Hydrogen atom which is a limiting case of the soft Coulomb problem as β --> 0 . CAW was supported by the Defense Threat Reduction Agency, and CAW and DG were both supported by the National Nuclear Security Agency.

  15. Method for isotope separation by photodeflection

    DOEpatents

    Bernhardt, Anthony F.

    1977-01-01

    In the method of separating isotopes wherein a desired isotope species is selectively deflected out of a beam of mixed isotopes by irradiating the beam with a directed beam of light of narrowly defined frequency which is selectively absorbed by the desired species, the improvement comprising irradiating the deflected beam with light from other light sources whose frequencies are selected to cause the depopulation of any metastable excited states.

  16. Structure Effects in Collisions Induced by Halo and Weakly Bound Nuclei around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Scuderi, V.; di Pietro, A.; Acosta, L.; Amorini, F.; Borge, M. J. G.; Figuera, P.; Fisichella, M.; Fraile, L. M.; Gomez-Camacho, J.; Jeppesen, H.; Lattuada, M.; Martel, I.; Milin, M.; Musumarra, A.; Papa, M.; Pellegriti, M. G.; Raabe, R.; Randisi, G.; Rizzo, F.; Santonocito, D.; Sanchez, E. M. R.; Scalia, G.; Tengblad, O.; Torresi, D.; Vidal, A. M.; Zadro, M.

    In this contribution, results concerning different reaction channels for the collisions induced by the three Be isotopes, 9,10,11Be, on a 64Zn target at energies around the Coulomb barrier will be presented. The experiments with the radioactive 10,11Be beams were performed at REX-ISOLDE (CERN) whereas the experiment with the stable weakly bound 9Be beam was performed at LNS Catania. Elastic scattering angular distributions have been measured for the three systems 9,10,11Be + 64Zn at the same center of mass energy. The angular distributions were analyzed with optical potentials and reaction cross sections were obtained from optical model calculations, performed with the code PTOLEMY. For the 11Be + 64Zn reaction, the break-up angular distribution was also measured.

  17. Spin blockade and exchange in Coulomb-confined silicon double quantum dots.

    PubMed

    Weber, Bent; Tan, Y H Matthias; Mahapatra, Suddhasatta; Watson, Thomas F; Ryu, Hoon; Rahman, Rajib; Hollenberg, Lloyd C L; Klimeck, Gerhard; Simmons, Michelle Y

    2014-06-01

    Electron spins confined to phosphorus donors in silicon are promising candidates as qubits because of their long coherence times, exceeding seconds in isotopically purified bulk silicon. With the recent demonstrations of initialization, readout and coherent manipulation of individual donor electron spins, the next challenge towards the realization of a Si:P donor-based quantum computer is the demonstration of exchange coupling in two tunnel-coupled phosphorus donors. Spin-to-charge conversion via Pauli spin blockade, an essential ingredient for reading out individual spin states, is challenging in donor-based systems due to the inherently large donor charging energies (∼45 meV), requiring large electric fields (>1 MV m(-1)) to transfer both electron spins onto the same donor. Here, in a carefully characterized double donor-dot device, we directly observe spin blockade of the first few electrons and measure the effective exchange interaction between electron spins in coupled Coulomb-confined systems. PMID:24727686

  18. Large degeneracy of excited hadrons and quark models

    SciTech Connect

    Bicudo, P.

    2007-11-01

    The pattern of a large approximate degeneracy of the excited hadron spectra (larger than the chiral restoration degeneracy) is present in the recent experimental report of Bugg. Here we try to model this degeneracy with state of the art quark models. We review how the Coulomb Gauge chiral invariant and confining Bethe-Salpeter equation simplifies in the case of very excited quark-antiquark mesons, including angular or radial excitations, to a Salpeter equation with an ultrarelativistic kinetic energy with the spin-independent part of the potential. The resulting meson spectrum is solved, and the excited chiral restoration is recovered, for all mesons with J>0. Applying the ultrarelativistic simplification to a linear equal-time potential, linear Regge trajectories are obtained, for both angular and radial excitations. The spectrum is also compared with the semiclassical Bohr-Sommerfeld quantization relation. However, the excited angular and radial spectra do not coincide exactly. We then search, with the classical Bertrand theorem, for central potentials producing always classical closed orbits with the ultrarelativistic kinetic energy. We find that no such potential exists, and this implies that no exact larger degeneracy can be obtained in our equal-time framework, with a single principal quantum number comparable to the nonrelativistic Coulomb or harmonic oscillator potentials. Nevertheless we find it plausible that the large experimental approximate degeneracy will be modeled in the future by quark models beyond the present state of the art.

  19. Electromagnetic properties of the first 2+1 excited states in 100,102,104Ru

    NASA Astrophysics Data System (ADS)

    Hirata, J. H.; Salém-Vasconcelos, S.; Bechara, M. J.; Gomes, L. C.; Dietzsch, O.

    1998-01-01

    Measurements of Coulomb excitation probabilities of the first 2+1 state of 100,102,104Ru were carried out using back-scattered ions of 4He and 16O. The static quadrupole moments Q2+1 and the reduced transition probabilities B(E20+1-->2+1) have been determined using the reorientation effect. The quadrupole moments Q2+1 deduced for the positive sign of the 2+2 interference term are -0.54+/-0.07 eb, -0.64+/-0.05 eb, -0.62+/-0.08 eb for 100Ru, 102Ru, and 104Ru, respectively. The reduced transition probabilities B(E20+1-->2+1) are 0.493+/-0.003 e2b2, 0.614+/-0.004 e2b2, and 0.809+/-0.006 e2b2, respectively. A compilation of the available experimental results for the reduced eletric quadrupole transition probability B(E20+1-->2+1) and for the static quadrupole moments Q2+1 for the even ruthenium stable isotopes (96<=A<=104) are presented.

  20. Mass-independent isotope effects.

    PubMed

    Buchachenko, Anatoly L

    2013-02-28

    Three fundamental properties of atomic nuclei-mass, spin (and related magnetic moment), and volume-are the source of isotope effects. The mostly deserved and popular, with almost hundred-year history, is the mass-dependent isotope effect. The first mass-independent isotope effect which chemically discriminates isotopes by their nuclear spins and nuclear magnetic moments rather than by their masses was detected in 1976. It was named as the magnetic isotope effect because it is controlled by magnetic interaction, i.e., electron-nuclear hyperfine coupling in the paramagnetic species, the reaction intermediates. The effect follows from the universal physical property of chemical reactions to conserve angular momentum (spin) of electrons and nuclei. It is now detected for oxygen, silicon, sulfur, germanium, tin, mercury, magnesium, calcium, zinc, and uranium in a great variety of chemical and biochemical reactions including those of medical and ecological importance. Another mass-independent isotope effect was detected in 1983 as a deviation of isotopic distribution in reaction products from that which would be expected from the mass-dependent isotope effect. On the physical basis, it is in fact a mass-dependent effect, but it surprisingly results in isotope fractionation which is incompatible with that predicted by traditional mass-dependent effects. It is supposed to be a function of dynamic parameters of reaction and energy relaxation in excited states of products. The third, nuclear volume mass-independent isotope effect is detected in the high-resolution atomic and molecular spectra and in the extraction processes, but there are no unambiguous indications of its importance as an isotope fractionation factor in chemical reactions. PMID:23301791

  1. Reconfiguration of a Nadir-Pointing 2-Craft Coulomb Tether

    NASA Astrophysics Data System (ADS)

    Natarajan, A.; Schaub, H.; Parker, G. G.

    The linear dynamics and stability analysis of reconfiguring a 2-spacecraft Coulomb tether formation is investigated. In this concept the tether between two craft is replaced with electrostatic force fields. Here the relative distance between the two satellites is increased or decreased using electrostatic Coulomb forces. The two craft are connected by an electrostatic tether which is capable of both tensile and compressive forces. The resulting virtual structure can change its shape by modifying the desired reference length. As a result, the two-craft formation will essentially act as a long, slender, nearly-rigid body of variable length. Inter-spacecraft Coulomb forces cannot influence the inertial angular momentum of this formation. However, the gravity gradient effect can be exploited to stabilize the attitude of this Coulomb tether formation about an orbit radial direction. Limits of the Coulomb tether expansion and contraction rates are discussed using linearized time-varying dynamical models. These allow the reference length time histories to be designed while ensuring linear stability of the virtual structure.

  2. Coulomb versus physical string tension on the lattice

    NASA Astrophysics Data System (ADS)

    Burgio, Giuseppe; Quandt, Markus; Reinhardt, Hugo; Vogt, Hannes

    2015-08-01

    From continuum studies it is known that the Coulomb string tension σC gives an upper bound for the physical (Wilson) string tension σW [D. Zwanziger, Phys. Rev. Lett. 90, 102001 (2003)]. How does such a relationship translate to the lattice, however? In this paper we give evidence that on the lattice, while the two string tensions are related at zero temperature, they decouple at finite temperature. More precisely, we show that on the lattice the Coulomb gauge confinement scenario is always tied to the spatial string tension, which is known to survive the deconfinement phase transition and to cause screening effects in the quark-gluon plasma. Our analysis is based on the identification and elimination of center vortices, which allows us to control the physical string tension and study its effect on the Coulomb gauge observables. We also show how alternative definitions of the Coulomb potential may sense the deconfinement transition; however, a true static Coulomb gauge order parameter for the phase transition is still elusive on the lattice.

  3. Marine ice sheet profiles and stability under Coulomb basal conditions

    NASA Astrophysics Data System (ADS)

    Tsai, Victor; Stewart, Andrew; Thompson, Andrew

    2015-04-01

    The behavior of marine-terminating ice sheets, like the West Antarctic Ice Sheet, is of interest due to the possibility of rapid grounding line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to relate the ice sheet velocity to a power-law function of basal stress. Recent experiments, however, suggest that near-grounding line tills exhibit Coulomb friction behavior. Here we address how Coulomb conditions modify ice sheet profiles and stability criteria. The basal rheology necessarily transitions to Coulomb friction near the grounding line due to low effective stresses, leading to changes in ice sheet properties within a narrow boundary layer. Ice sheet profiles 'taper off' towards a flatter upper surface, compared to the power-law case, and basal stresses vanish at the grounding line, consistent with observations. In the Coulomb case, the grounding line ice flux also depends more strongly on flotation ice thickness, which implies that ice sheets are more sensitive to climate perturbations. Furthermore, with Coulomb friction, the ice sheet grounds stably in shallower water than with a power-law rheology. This implies that smaller perturbations are required to push the grounding line into regions of negative bed slope, where it would become unstable. These results have important implications for ice sheet stability in a warming climate.

  4. 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.

  5. Coulomb effect and threshold effect in electronic stopping power for slow protons

    SciTech Connect

    Semrad, D.

    1986-03-01

    We show how the electronic stopping power for slow protons is influenced by the deceleration and deflection of the projectile in the field of the target nucleus (Coulomb effect) and by the fact that in insulators a finite energy is also required for excitation of the outermost electrons (threshold effect). Estimates are derived from the Fermi-Teller description of the stopping process, from a modified local-density approximation, and from measured inner-shell ionization cross sections. It is found that the introduction of an energy threshold reduces at low energies the stopping cross section by a large factor and hence leads to an appreciable deviation from v/sub 1/ proportionality.

  6. Geometry-dependent lifetime of Interatomic coulombic decay using equation-of-motion coupled cluster method

    SciTech Connect

    Ghosh, Aryya; Vaval, Nayana

    2014-12-21

    Electronically excited atom or molecule in an environment can relax via transferring its excess energy to the neighboring atoms or molecules. The process is called Interatomic or Intermolecular coulombic decay (ICD). The ICD is a fast decay process in environment. Generally, the ICD mechanism predominates in weakly bound clusters. In this paper, we have applied the complex absorbing potential approach/equation-of-motion coupled cluster (CAP/EOMCCSD) method which is a combination of CAP and EOMCC approach to study the lifetime of ICD at various geometries of the molecules. We have applied this method to calculate the lifetime of ICD in Ne-X; X = Ne, Mg, Ar, systems. We compare our results with other theoretical and experimental results available in literature.

  7. Coherence of inter-Coulombic (ICD) and electron transfer mediated (ETMD) decay in endofullerenes

    NASA Astrophysics Data System (ADS)

    de, Ruma; Magrakvelidze, Maia; Madjet, Mohamed; Manson, Steven T.; Chakraborty, Himadri

    2016-05-01

    For the photoionization of noble gas endofullerenes, the decay of fullerene innershell vacancies through the continuum of a subvalent electron in the confined atom via the inter-Coulombic decay (ICD) pathway is calculated in the time-dependent local density approximation (TDLDA) scheme. Excitations to atom-fullerene hybrid states indicate coherence between ICD and electron-transfer mediated decay (ETMD). This coherence requires that both the fullerene and the trapped atom have dipole-allowed final states, continuum and quasi-discrete, of the same symmetry. This should be the dominant above-threshold decay process for a variety of confined systems, and the strength of these resonances is such that they should be accessible for study by photoelectron spectroscopy. The work is supported by US NSF and DOE, Basic Energy Sciences.

  8. Coulomb dissociation of 27P at 500 MeV/u

    NASA Astrophysics Data System (ADS)

    Marganiec, J.; Beceiro Novo, S.; Typel, S.; Langer, C.; Wimmer, C.; Alvarez-Pol, H.; Aumann, T.; Boretzky, K.; Casarejos, E.; Chatillon, A.; Cortina-Gil, D.; Datta-Pramanik, U.; Elekes, Z.; Fulop, Z.; Galaviz, D.; Geissel, H.; Giron, S.; Greife, U.; Hammache, F.; Heil, M.; Hoffman, J.; Johansson, H.; Kiselev, O.; Kurz, N.; Larsson, K.; Le Bleis, T.; Litvinov, Yu. A.; Mahata, K.; Muentz, C.; Nociforo, C.; Ott, W.; Paschalis, S.; Plag, R.; Prokopowicz, W.; Rodríguez Tajes, C.; Rossi, D. M.; Simon, H.; Stanoiu, M.; Stroth, J.; Sümmerer, K.; Wagner, A.; Wamers, F.; Weick, H.; Wiescher, M.; R3B Collaboration

    2016-04-01

    The proton-capture reaction 26Si(p ,γ )27P was studied via Coulomb dissociation (CD) of 27P at an incident energy of about 500 MeV/u. The three lowest-lying resonances in 27P have been populated and their resonance strengths have been measured. In addition, a nonresonant direct-capture component was clearly identified and its astrophysical S factor measured. The experimental results are compared to Monte Carlo simulations of the CD process using a semiclassical model. Our thermonuclear reaction rates show good agreement with the rates from a recent compilation. With respect to the nuclear structure of 27P we have found evidence for a negative-parity intruder state at 2.88-MeV excitation energy.

  9. Strong enhancement of cage effects in water photolysis caused by interatomic Coulombic decay

    NASA Astrophysics Data System (ADS)

    Jabbari, Ghazal; Sadri, Keyvan; Cederbaum, Lorenz S.; Gokhberg, Kirill

    2016-04-01

    The impact of the solvent on the photodissociation of embedded molecules has been intensively investigated in the last decades. Collisions of photofragments with the solvating atoms or molecules can change their kinetic energy distribution or even lead to the de-excitation of the dissociating molecule to a bound electronic state quenching the dissociation. In this article we show that this cage effect is strongly enhanced if interatomic Coulombic decay (ICD) of the excited state becomes allowed. Ab initio calculations in H2O-Cl- cluster show that the ultra-fast dissociation of water in the A ˜ excited state is strongly quenched by ICD. We found that this very efficient quenching is due to two factors. First, the lifetimes of the A ˜ state due to ICD are short ranging between 6 and 30 fs. Second, nuclear dynamics is dominated by the chattering motion of the H atom between O and Cl- allowing ICD to act for longer times. We hope that this work will be an important first step in clarifying the impact of ICD on photodissociation of embedded molecules.

  10. Fermi surface versus Fermi sea contributions to intrinsic anomalous and spin Hall effects of multiorbital metals in the presence of Coulomb interaction and spin-Coulomb drag

    NASA Astrophysics Data System (ADS)

    Arakawa, Naoya

    2016-06-01

    Anomalous Hall effect (AHE) and spin Hall effect (SHE) are fundamental phenomena, and their potential for application is great. However, we understand the interaction effects unsatisfactorily, and should have clarified issues about the roles of the Fermi sea term and Fermi surface term of the conductivity of the intrinsic AHE or SHE of an interacting multiorbital metal and about the effects of spin-Coulomb drag on the intrinsic SHE. Here, we resolve the first issue and provide the first step about the second issue by developing a general formalism in the linear response theory with appropriate approximations and using analytic arguments. The most striking result is that even without impurities, the Fermi surface term, a non-Berry-curvature term, plays dominant roles at high or slightly low temperatures. In particular, this Fermi surface term causes the temperature dependence of the dc anomalous Hall or spin Hall conductivity due to the interaction-induced quasiparticle damping and the correction of the dc spin Hall conductivity due to the spin-Coulomb drag. Those results revise our understanding of the intrinsic AHE and SHE. We also find that the differences between the dc anomalous Hall and longitudinal conductivities arise from the difference in the dominant multiband excitations. This not only explains why the Fermi sea term such as the Berry-curvature term becomes important in clean and low-temperature case only for interband transports, but also provides the useful principles on treating the electron-electron interaction in an interacting multiorbital metal for general formalism of transport coefficients. Several correspondences between our results and experiments are finally 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. Generation of Rydberg states of hydrogen atoms with intense laser pulses: The roles of Coulomb force and initial lateral momentum

    NASA Astrophysics Data System (ADS)

    Zhang, Bin; Chen, Wenbo; Zhao, Zengxiu

    2014-08-01

    We investigate the generation of Rydberg states of hydrogen atoms with intense laser pulses by solving the time-dependent Schrödinger equation and by means of classical-trajectory Monte Carlo simulations. Both linearly polarized multicycle pulses and pairs of optical half-cycle pulses are used. Comparisons between these methods show that both the Coulomb force and initial lateral momentum, which have effects on the n distribution and l distribution of the population of excited states, are important in the generation of Rydberg states.

  13. Weak interaction rate Coulomb corrections in big bang nucleosynthesis

    SciTech Connect

    Smith, Christel J.; Fuller, George M.

    2010-03-15

    We have applied a fully relativistic Coulomb wave correction to the weak reactions in the full Kawano/Wagoner big bang nucleosynthesis (BBN) code. We have also added the zero-temperature radiative correction. We find that using this higher accuracy Coulomb correction results in good agreement with previous work, giving only a modest {approx}0.04% increase in helium mass fraction over correction prescriptions applied previously in BBN calculations. We have calculated the effect of these corrections on other light element abundance yields in BBN, and we have studied these yields as functions of electron neutrino lepton number. This has allowed insights into the role of the weak neutron-proton interconversion processes in the setting of the neutron-to-proton ratio during the BBN epoch. We find that the lepton capture processes' contributions to this ratio are only second order in the Coulomb correction.

  14. Imaging quantum Hall Coulomb islands inside a quantum ring

    NASA Astrophysics Data System (ADS)

    Martins, Frederico; Hackens, Benoit; Faniel, Sebastien; Bayot, Vincent; Pala, Marco; Sellier, Hermann; Huant, Serge; Desplanque, Ludovic; Wallart, Xavier

    2011-03-01

    In the quantum Hall regime near integer filling factors, electrons are transmitted through edge states confined at the borders of the device. In mesoscopic samples, however, edge states may be sufficiently close to allow electrons to tunnel, or to be transmitted through localized states (``Coulomb islands''). Here, we use the biased tip of a low temperature scanning gate microscope to alter tunneling through quantum Hall Coulomb islands localized inside a quantum ring patterned in an InGaAs/InAlAs heterostructure. Simultaneously, we map the quantum ring resistance and observe different sets of concentric resistance fringes, due to charging/discharging of each Coulomb island. Tuning the magnetic field and the tip voltage, we reveal the rich and complex behaviour of these fringes.

  15. Oxygen Isotopes in Meteorites

    NASA Astrophysics Data System (ADS)

    Clayton, R. N.

    2003-12-01

    et al., 1996). In their paper reporting the discovery of 18O in the Earth's atmosphere, Giauque and Johnston (1929) refer to nonuniform distribution of oxygen isotopes as a "remote possibility," whereas Manian et al. (1934) sought to find variations in oxygen isotope abundances in meteorites as evidence for an origin outside the solar system.In addition to the abundance variations due to nuclear processes, there are important isotopic variations produced within molecular clouds, the precursors to later star-formation. The most important process is isotopic self-shielding in the UV photodissociation of CO (van Dishoeck and Black, 1988). This process results from the large differences in abundance between C16O, on the one hand, and C17O and C18O on the other. Photolysis of CO occurs by absorption of stellar UV radiation in the wavelength range 90-100 nm. The reaction proceeds by a predissociation mechanism, in which the excited electronic state lives long enough to have well-defined vibrational and rotational energy levels. As a consequence, the three isotopic species - C16O, C17O, and C18O - absorb at different wavelengths, corresponding to the isotope shift in vibrational frequencies. Because of their different number densities, the abundant C16O becomes optically thick in the outermost part of the cloud (nearest to the external source of UV radiation), while the rare C17O and C18O remain optically thin, and hence dissociate at a greater rate in the cloud interior. The differences in chemical reactivity between C16O molecules and 17O and 18O atoms may lead to isotopically selective reaction products. This scenario has been suggested to explain meteoritic isotope patterns, as discussed below (Yurimoto and Kuramoto, 2002).Stable isotope abundances in meteoritic material provide an opportunity to evaluate the thoroughness of mixing of isotopes of diverse stellar sources. Molybdenum presents a good test case: it has seven stable isotopes, derived from at least three

  16. Selective photoionisation of lutetium isotopes

    SciTech Connect

    D'yachkov, Aleksei B; Kovalevich, S K; Labozin, Valerii P; Mironov, Sergei M; Panchenko, Vladislav Ya; Firsov, Valerii A; Tsvetkov, G O; Shatalova, G G

    2012-10-31

    A three-stage laser photoionisation scheme intended for enriching the {sup 176}Lu isotope from natural lutetium was considered. An investigation was made of the hyperfine structure of the second excited state 5d6s7s {yields} {sup 4}D{sub 3/2} with an energy of 37194 cm{sup -1} and the autoionisation state with an energy of 53375 cm{sup -1} of the {sup 176}Lu and {sup 175}Lu isotopes. The total electron momentum of the autoionisation level and the constant A of hyperfine magnetic interaction were determined. Due to a small value of the isotopic shift between {sup 176}Lu and {sup 175}Lu, appreciable selectivity of their separation may be achieved with individual hyperfine structure components. The first tentative enrichment of the 176Lu isotope was performed to a concentration of 60 % - 70 %. (laser applications and other topics in quantum electronics)

  17. 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.

  18. Hydrodynamic Coulomb drag of strongly correlated electron liquids

    NASA Astrophysics Data System (ADS)

    Apostolov, S. S.; Levchenko, A.; Andreev, A. V.

    2014-03-01

    We develop a theory of Coulomb drag in ultraclean double layers with strongly correlated carriers. In the regime where the equilibration length of the electron liquid is shorter than the interlayer spacing the main contribution to the Coulomb drag arises from hydrodynamic density fluctuations. The latter consist of plasmons driven by fluctuating longitudinal stresses, and diffusive modes caused by temperature fluctuations and thermal expansion of the electron liquid. We express the drag resistivity in terms of the kinetic coefficients of the electron fluid. Our results are nonperturbative in interaction strength and do not assume Fermi-liquid behavior of the electron liquid.

  19. Strong Coulomb effects in hole-doped Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Schnack, J.

    2005-06-01

    Substances such as the “telephone number compound” Sr14Cu24O41 are intrinsically hole-doped. The involved interplay of spin and charge dynamics is a challenge for theory. In this article we propose to describe hole-doped Heisenberg spin rings by means of complete numerical diagonalization of a Heisenberg Hamiltonian that depends parametrically on hole positions and includes the screened Coulomb interaction among the holes. It is demonstrated that key observables like magnetic susceptibility, specific heat, and inelastic neutron scattering cross section depend sensitively on the dielectric constant of the screened Coulomb potential.

  20. Observation of ionic Coulomb blockade in nanopores.

    PubMed

    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. PMID:27019385

  1. On rate-state and Coulomb failure models

    USGS Publications Warehouse

    Gomberg, J.; Beeler, N.; Blanpied, M.

    2000-01-01

    We examine the predictions of Coulomb failure stress and rate-state frictional models. We study the change in failure time (clock advance) Δt due to stress step perturbations (i.e., coseismic static stress increases) added to "background" stressing at a constant rate (i.e., tectonic loading) at time t0. The predictability of Δt implies a predictable change in seismicity rate r(t)/r0, testable using earthquake catalogs, where r0 is the constant rate resulting from tectonic stressing. Models of r(t)/r0, consistent with general properties of aftershock sequences, must predict an Omori law seismicity decay rate, a sequence duration that is less than a few percent of the mainshock cycle time and a return directly to the background rate. A Coulomb model requires that a fault remains locked during loading, that failure occur instantaneously, and that Δt is independent of t0. These characteristics imply an instantaneous infinite seismicity rate increase of zero duration. Numerical calculations of r(t)/r0 for different state evolution laws show that aftershocks occur on faults extremely close to failure at the mainshock origin time, that these faults must be "Coulomb-like," and that the slip evolution law can be precluded. Real aftershock population characteristics also may constrain rate-state constitutive parameters; a may be lower than laboratory values, the stiffness may be high, and/or normal stress may be lower than lithostatic. We also compare Coulomb and rate-state models theoretically. Rate-state model fault behavior becomes more Coulomb-like as constitutive parameter a decreases relative to parameter b. This is because the slip initially decelerates, representing an initial healing of fault contacts. The deceleration is more pronounced for smaller a, more closely simulating a locked fault. Even when the rate-state Δt has Coulomb characteristics, its magnitude may differ by some constant dependent on b. In this case, a rate-state model behaves like a modified

  2. Higher-order dynamical effects in Coulomb dissociation

    SciTech Connect

    Esbensen, H.; Bertsch, G.F.; Bertulani, C.A.

    1995-08-01

    Coulomb dissociation is a technique commonly used to extract the dipole response of nuclei far from stability. This technique is applicable if the dissociation is dominated by dipole transitions and if first-order perturbation theory is valid. In order to assess the significance of higher-order processes we solve numerically the time evolution of the wave function for a two-body breakup in the Coulomb field from a high Z target. We applied this method to the breakup reactions: {sup 11}Be {yields} {sup 10}Be + n and {sup 11}Li {yields} +2n. The latter is treated as a two-body breakup, using a di-neutron model.

  3. Geometrically-frustrated pseudogap phase of Coulomb liquids

    NASA Astrophysics Data System (ADS)

    Pramudya, Y.; Terletska, H.; Pankov, S.; Manousakis, E.; Dobrosavljević, V.

    2012-06-01

    We study a class of models with long-range repulsive interactions of the generalized Coulomb form V(r)∼1/rα. We show that decreasing the interaction exponent in the regime αCoulomb liquid then survives in a broad pseudogap phase found at T>Tc, which is characterized by an unusual temperature dependence of all quantities. In contrast, the leading critical behavior very close to the charge-ordering temperature remains identical as in models with short-range interactions.

  4. 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.

  5. 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.

  6. 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.

  7. A non-variational approach to the quantum three-body Coulomb problem

    NASA Astrophysics Data System (ADS)

    Chi, Xuguang

    2005-07-01

    This thesis presents a general non-variational approach to the solution of three-body Schrodinger's equation with Coulomb interactions, based on the utilization of symmetries intrinsic to the three-body Laplacian operator first proposed by W. Y. Hsiang. Through step by step reductions, the center of mass degree of freedom is first removed, followed by the separation of all the rotational degrees of freedom, leading to a coupled partial differential equations (PDEs) in terms of the rotationally invariant internal variables {f1, f2, f3}. A crucial observation is that in the subspace where all the rotational degrees of freedom have been removed, there is an intrinsic spherical symmetry which can be fully utilized through the introduction of hyperspherical coordinates. By expressing the reduced Schrodinger's PDEs (with all the rotational degrees of freedom separated out) in terms of the hyperspherical coordinates, with the subsequent introduction of Jacobi polynomials as the angular eigenfunctions and Laguerre polynomials to expand the radial component, a system of infinite linear algebraic equations is obtained for the expansion coefficients. A numerical scheme is presented whereby the Coulomb interaction matrix elements are calculated to a very high degree of accuracy with minimal effort, and the truncation of the linear equations is carried out through a systematic procedure. The resulting matrix equations are solved through an iteration process, carried out on a PC. Numerical results are presented for the hydrogen negative ion H-, the helium and helium-like ions (Z = 3˜6), the hydrogen molecule ion H+2 and the positronium negative ion Ps-. Comparison with the variational and other approaches shows our results to be of comparable accuracy for the eigenenergies, but can yield highly accurate wave functions as by-products. Results on low-lying excited states are obtained simultaneously with the ground state properties with no extra effort. In particular, for the

  8. Study of M1 and E1 excitations by high-resolution proton inelastic scattering measurement at forward angles

    SciTech Connect

    Tamii, A.; Adachi, T.; Hatanaka, K.; Hashimoto, H.; Kaneda, T.; Matsubara, H.; Okamura, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Carter, J.; Dozono, M.; Fujita, H.; Fujita, Y.; Itoh, M.; Kawabata, T.; Nakanishi, K.; Sasamoto, Y.; Neumann-Cosel, P. von

    2007-06-13

    Experimental technique for measuring proton inelastic scattering with high-resolution at 295 MeV and at forward angles including zero degrees is described. The method is useful for extracting spin part of the M1 strength via nuclear excitation as well as E1 strength via Coulomb excitation. An excitation energy resolution of 20 keV, good scattering angle resolution, and low background condition have been achieved. The experimental technique was applied for several sd and pf shell nuclei.

  9. Excitation and photon decay of giant resonances excited by intermediate energy heavy ions

    SciTech Connect

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

    1987-01-01

    Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon /sup 17/O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the /sup 208/Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab.

  10. The spectroscopy of a benzil-bibenzyl mixed crystal system. Effects of isotopic substitution

    NASA Astrophysics Data System (ADS)

    Kohler, Bryan E.; Loda, Richard T.

    1981-05-01

    We report the T = 4.2 K, S0→S1 excitation and T1→S0 emission spectra of five different isotopic derivatives of benzil doped into bibenzyl single crystals. Selective excitation of the individual components of the isotopic mixtures has been observed. The 0-0 transition energy shifts with isotopic substitutions are additive, as may be expected for systems where geometry changes upon excitation consist primarily of linear displacements of the normal coordinates.

  11. 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.

  12. 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.

  13. Hamiltonian flow in Coulomb gauge Yang-Mills theory

    SciTech Connect

    Leder, Markus; Reinhardt, Hugo; Pawlowski, Jan M.; Weber, Axel

    2011-01-15

    We derive a new functional renormalization group equation for Hamiltonian Yang-Mills theory in Coulomb gauge. The flow equations for the static gluon and ghost propagators are solved under the assumption of ghost dominance within different diagrammatic approximations. The results are compared to those obtained in the variational approach and the reliability of the approximations is discussed.

  14. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    SciTech Connect

    Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

    2008-08-22

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  15. Coulomb Interactions in Hanbury Brown-Twiss Experiments with Electrons

    ERIC Educational Resources Information Center

    Shen, Kan

    2009-01-01

    This dissertation examines the effect of Coulomb interactions in Hanbury Brown-Twiss (HBT) type experiments with electrons. HBT experiments deal with intensity interference, which is related to the second-order correlation function of the particle field. This is an extension of the usual amplitude interference experiment, such as Young's…

  16. The Coulomb problem on a 3-sphere and Heun polynomials

    NASA Astrophysics Data System (ADS)

    Bellucci, Stefano; Yeghikyan, Vahagn

    2013-08-01

    The paper studies the quantum mechanical Coulomb problem on a 3-sphere. We present a special parametrization of the ellipto-spheroidal coordinate system suitable for the separation of variables. After quantization we get the explicit form of the spectrum and present an algebraic equation for the eigenvalues of the Runge-Lentz vector. We also present the wave functions expressed via Heun polynomials.

  17. The Coulomb problem on a 3-sphere and Heun polynomials

    SciTech Connect

    Bellucci, Stefano; Yeghikyan, Vahagn

    2013-08-15

    The paper studies the quantum mechanical Coulomb problem on a 3-sphere. We present a special parametrization of the ellipto-spheroidal coordinate system suitable for the separation of variables. After quantization we get the explicit form of the spectrum and present an algebraic equation for the eigenvalues of the Runge-Lentz vector. We also present the wave functions expressed via Heun polynomials.

  18. Coulomb Crystals in Cylindrical Dusty Plasmas under Gravity/Microgravity

    NASA Astrophysics Data System (ADS)

    Takahashi, Kazuo; Totsuji, Hiroo; Adachi, Satoshi

    2014-10-01

    Coulomb crystals of dusty plasmas have been studied under microgravity with utilities boarding on the International Space Station in a joint Russian/German research project. Dynamics of the Coulomb crystals in cylindrical plasmas is investigated with the apparatus of PK-4 being launched till the end of 2014. A science team in Japan studied the cylindrical dusty plasmas to contribute to the project with the PK-4J modified original for microgravity experiments of parabolic flights in Japan. In the experiments, the dust particles distributed at the off-centered position close to the bottom in balancing of gravity. Under microgravity, they changed the distribution and formed a Coulomb crystal around the center axis in the plasmas. Several particles arranged in a line parallel to the axis, and the lines piled up to a bundle. Spatial distribution of the dust particles affects on plasma parameters of ion density and electron temperature. Structures of the Coulomb crystals connected to the parameters are discussed. The present study were supported by JAXA and Diamond Air Service.

  19. Coulomb gauge approach for charmonium meson and hybrid radiative transitions

    NASA Astrophysics Data System (ADS)

    Gou, Peng; Yépez-Martínez, Tochtli; Szczepaniak, Adam P.

    2015-01-01

    We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.

  20. Interpolating the Coulomb phase of little string theory

    DOE PAGESBeta

    Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; Yin, Xi

    2015-12-03

    We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity onmore » the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.« less

  1. Interpolating the Coulomb phase of little string theory

    SciTech Connect

    Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; Yin, Xi

    2015-12-03

    We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.

  2. Interpolating the Coulomb phase of little string theory

    NASA Astrophysics Data System (ADS)

    Lin, Ying-Hsuan; Shao, Shu-Heng; Wang, Yifan; Yin, Xi

    2015-12-01

    We study up to 8-derivative terms in the Coulomb branch effective action of (1, 1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU( k) SYM and DSLST respectively, for k = 2 , 3 , 4 , 5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. We also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2 , 0) little string theory.

  3. Accurate Coulomb blockade thermometry up to 60 kelvin.

    PubMed

    Meschke, M; Kemppinen, A; Pekola, J P

    2016-03-28

    We demonstrate experimentally a precise realization of Coulomb blockade thermometry working at temperatures up to 60 K. Advances in nano-fabrication methods using electron beam lithography allow us to fabricate uniform arrays of sufficiently small tunnel junctions to guarantee an overall temperature reading precision of about 1%. PMID:26903107

  4. 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.

  5. Coulomb gauge approach for charmonium meson and hybrid radiative transitions

    DOE PAGESBeta

    Gou, Peng; Yepez-Martínez, Tochtli; Szczepaniak, Adam P.

    2015-01-22

    We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.

  6. 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.

  7. Using the Screened Coulomb Potential to Illustrate the Variational Method

    ERIC Educational Resources Information Center

    Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

    2012-01-01

    The screened Coulomb potential, or Yukawa potential, is used to illustrate the application of the single and linear variational methods. The trial variational functions are expressed in terms of Slater-type functions, for which the integrals needed to carry out the variational calculations are easily evaluated in closed form. The variational…

  8. Coulomb effects on edge scattering in elastic nuclear collisions

    SciTech Connect

    Silveira, R. da; Leclercq-Willain, Ch.

    2011-04-15

    We present a qualitative analysis of the effects of the Coulomb force on the edge scattering produced in elastic nuclear collisions occurring under strong absorption conditions. This analysis is illustrated with several examples of nucleus-nucleus and antiproton-nucleus elastic scattering.

  9. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, Charles G. [Pleasanton, CA

    1978-08-29

    A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, .sup.235 UF.sub.6 is separated from a UF.sub.6 mixture by selective excitation followed by dissociative electron capture into .sup.235 UF.sub.5 - and F.

  10. Isotope separation by photoselective dissociative electron capture

    DOEpatents

    Stevens, C.G.

    1978-08-29

    Disclosed is a method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, [sup 235]UF[sub 6] is separated from a UF[sub 6] mixture by selective excitation followed by dissociative electron capture into [sup 235]UF[sub 5]- and F. 2 figs.

  11. Electron and nuclear dynamics of molecular clusters in ultraintense laser fields. IV. Coulomb explosion of molecular heteroclusters.

    PubMed

    Last, Isidore; Jortner, Joshua

    2004-11-01

    =E(j,M). These results for uniform Coulomb explosion serve as benchmark reference data for the assessment of the effects of nonuniform explosion, where the CVI scaling law for the energetics still holds, with deviations of the a coefficient, which increase with increasing eta. Kinematic effects (for eta>1) result in an isotope effect, predicting the enhancement (by 9%-11%) of E(H,av) for Coulomb explosion of (C(4+)H(4) (+))(eta) (eta=3) relative to E(D,av) for Coulomb explosion of (C(4+)D(4) (+))(eta) (eta=1.5), with the isotope effect being determined by the ratio of the kinematic parameters for the pair of Coulomb exploding clusters. Kinematic effects for nonuniform explosion also result in a narrow isotope dependent energy distribution (of width DeltaE) of the light ions (with DeltaE/E(H,av) approximately 0.3 and DeltaE/E(D,av) approximately 0.4), with the distribution peaking at the high energy edge, in marked contrast with the uniform explosion case. Features of laser-heterocluster interactions were inferred from the analyses of the intensity dependent boundary radii (R(0))(I) and the corresponding average D+ ion energies (E(D,av))(I), which provide a measure for optimization of the cluster size at intensity I for the neutron yield from dd nuclear fusion driven by Coulomb explosion (NFDCE) of these heteroclusters. We infer on the advantage of deuterium containing heteronuclear clusters, e.g., (CD4)(n) in comparison to homonuclear clusters, e.g., (D2)(n/2), for dd NFDCE, where the highly charged heavy ions (e.g., C4+ or C6+) serve as energetic and kinematic triggers driving the D+ ions to a high (10-200 keV) energy domain. PMID:15511153

  12. Concepts of Highly Excited Electronic Systems

    NASA Astrophysics Data System (ADS)

    Berakdar, Jamal

    2003-05-01

    Knowledge of the excitation characteristics of matter is decisive for the descriptions of a variety of dynamical processes, which are of significant technological interest. E.g. transport properties and the optical response are controlled by the excitation spectrum. This self-contained work is a coherent presentation of the quantum theory of correlated few-particle excitations in electronic systems. It begins with a compact resume of the quantum mechanics of single particle excitations. Particular emphasis is put on Green function methods, which offer a natural tool to unravel the relations between the physics of small and large electronic systems. The book contains explicit expressions for the Coulomb Green function of two charge particles and a generalization to three-body systems. Techniques for the many-body Green function of finite systems are introduced and some explicit calculations of the Green functions are given. Concrete examples are provided and the theories are contrasted with experimental data, when available. The second volume presents an up-to-date selection of applications of the developed concepts and a comparison with available experiments is made

  13. Exciton Transport and Perfect Coulomb Drag

    NASA Astrophysics Data System (ADS)

    Nandi, Debaleena

    2013-03-01

    Exciton condensation is realized in closely-spaced bilayer quantum Hall systems at νT = 1 when the total density in the two 2D electron layers matches the Landau level degeneracy. In this state, electrons in one layer become tightly bound to holes in the other layer, forming a condensate similar to the Cooper pairs in a superconductor. Being charge neutral, these excitons ought to be free to move throughout the bulk of the quantum Hall fluid. One therefore expects that electron current driven in one layer would spontaneously generate a ``hole'' current in the other layer, even in the otherwise insulating bulk of the 2D system. We demonstrate precisely this effect, using a Corbino geometry to defeat edge state transport. Our sample contains two essentially identical two-dimensional electron systems (2DES) in GaAs quantum wells separated by a thin AlGaAs barrier. It is patterned into an annulus with arms protruding from each rim that provide contact to each 2DES separately. A current drag geometry is realized by applying a drive voltage between the outer and inner rim on one 2DES layer while the two rims on the opposite layer are connected together in a closed loop. There is no direct electrical connection between the two layers. At νT = 1 the bulk of the Corbino annulus becomes insulating owing to the quantum Hall gap and net charge transport across the bulk is suppressed. Nevertheless, we find that in the drag geometry appreciable currents do flow in each layer. These currents are almost exactly equal magnitude but, crucially, flow in opposite directions. This phenomenon reflects exciton transport within the νT = 1 condensate, rather than its quasiparticle excitations. We find that quasiparticle transport competes with exciton transport at elevated temperatures, drive levels, and layer separations. This work represents a collaboration with A.D.K. Finck, J.P. Eisenstein, L.N. Pfeiffer and K.W. West. This work is supported by the NSF under grant DMR-1003080.

  14. Determination of the transport properties of ultrasonic waves traveling in piezoelectric crystals by imaging with Coulomb coupling

    NASA Astrophysics Data System (ADS)

    Habib, A.; Shelke, A.; Pietsch, U.; Kundu, T.; Grill, W.

    2012-04-01

    Coulomb coupling has been applied for imaging of bulk and guided acoustic waves propagating in a 0.5 mm thick, z cut Lithium Niobate single-crystal. The excitation and detection of acoustic waves was performed by localized electrical field probes. The developed scheme has been applied to imaging of the transport properties of skimming longitudinal and guided acoustic waves. A short pulse of 20 ns has been used for the excitation of acoustic waves. Broadband coupling is achieved since neither mechanical nor electrical resonances are involved. The attenuation of acoustic waves in piezoelectric crystals is studied by this method. A thin film of conductive silver paint was deposited on the surface of the crystal acting as an acoustic attenuator inducing also mass loading effects and shortening of electrical fields. The group velocities of the propagating acoustic waves for both conditions, with and without the conductive silver paint film, are determined from the propagation of the acoustic wave fronts.

  15. Compact Collision Kernels for Hard Sphere and Coulomb Cross Sections; Fokker-Planck Coefficients

    SciTech Connect

    Chang Yongbin; Shizgal, Bernie D.

    2008-12-31

    A compact collision kernel is derived for both hard sphere and Coulomb cross sections. The difference between hard sphere interaction and Coulomb interaction is characterized by a parameter {eta}. With this compact collision kernel, the calculation of Fokker-Planck coefficients can be done for both the Coulomb and hard sphere interactions. The results for arbitrary order Fokker-Planck coefficients are greatly simplified. An alternate form for the Coulomb logarithm is derived with concern to the temperature relaxation in a binary plasma.

  16. Isotopic chirality

    SciTech Connect

    Floss, H.G.

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  17. Transuranium isotopes

    SciTech Connect

    Hoffman, D.C.

    1985-12-01

    The needs of the research community for the production of transuranium isotopes, the quantities required, the continuity of production desired, and what a new steady state neutron source would have to provide to satisfy these needs are discussed. Examples of past frontier research which need these isotopes as well as an outline of the proposed Large Einsteinium Activation Program, LEAP, which requires roughly ten times the current production of /sup 254/Es are given. 15 refs., 5 figs., 4 tabs.

  18. Isotopic Dependence of the Nuclear Caloric Curve

    SciTech Connect

    Sfienti, C.; Adrich, P.; Aumann, T.; Bianchin, S.; Emling, H.; Hellstroem, M.; Henzlova, D.; Johansson, H.; Kezzar, K.; Le Fevre, A.; Leifels, Y.; Luehning, J.; Lynen, U.; Mueller, W. F. J.; Orth, H.; Otte, A. N.; Palit, R.; Sann, H.; Schwarz, C.; Simon, H.

    2009-04-17

    The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of {sup 124}Sn and radioactive beams of {sup 124}La and {sup 107}Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects ({delta}T{approx_equal}0.6 MeV) appear for residue production near the onset of multifragmentation.

  19. Complex-scaling of screened Coulomb potentials for resonance calculations utilizing the modified Bessel functions

    NASA Astrophysics Data System (ADS)

    Jiao, Li-Guang; Ho, Yew Kam

    2014-05-01

    The screened Coulomb potential (SCP) has been extensively used in atomic physics, nuclear physics, quantum chemistry and plasma physics. However, an accurate calculation for atomic resonances under SCP is still a challenging task for various methods. Within the complex-scaling computational scheme, we have developed a method utilizing the modified Bessel functions to calculate doubly-excited resonances in two-electron atomic systems with configuration interaction-type basis. To test the validity of our method, we have calculated S- and P-wave resonance states of the helium atom with various screening strengths, and have found good agreement with earlier calculations using different methods. Our present method can be applied to calculate high-lying resonances associated with high excitation thresholds of the He+ ion, and with high-angular-momentum states. The derivation and calculation details of our present investigation together with new results of high-angular-momentum states will be presented at the meeting. Supported by NSC of Taiwan.

  20. Modeling anisotropic plasmon excitations in self-assembled fullerenes

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The plasmon excitations in Coulomb-coupled spherical two-dimensional electron gases (S2DEGs) reveal an interesting dependence on the displacement vector between the centers of the spheres with respect to the axis of quantization for the angular momentum quantum number L. Specifically, plasmon modes for a bundle of three S2DEGs have been obtained within the random-phase approximation. The inter-sphere Coulomb interaction matrix elements and their symmetry properties were also investigated in detail. The case of a bundle gives an adequate picture of the way in which the Coulomb interaction depends on the orbital angular momentum quantum number L and its projection M. We concluded that the interaction between the S2DEGs aligned at an angle of 45° with the axis of quantization is negligible compared to the interaction along and perpendicular to the quantization axis, which are themselves unequal to each other. Consequently, the plasmon excitation frequencies reveal an interesting orientational anisotropic coupling to an external electromagnetic field probing the charge density oscillations. Our result on the spatial correlation may be experimentally observable. In this connection, there have already been some experimental reports pointing to a similar effect in nanoparticles.

  1. Photoionization of furan from the ground and excited electronic states

    NASA Astrophysics Data System (ADS)

    Ponzi, Aurora; Sapunar, Marin; Angeli, Celestino; Cimiraglia, Renzo; Došlić, Nada; Decleva, Piero

    2016-02-01

    Here we present a comparative computational study of the photoionization of furan from the ground and the two lowest-lying excited electronic states. The study aims to assess the quality of the computational methods currently employed for treating bound and continuum states in photoionization. For the ionization from the ground electronic state, we show that the Dyson orbital approach combined with an accurate solution of the continuum one particle wave functions in a multicenter B-spline basis, at the density functional theory (DFT) level, provides cross sections and asymmetry parameters in excellent agreement with experimental data. On the contrary, when the Dyson orbitals approach is combined with the Coulomb and orthogonalized Coulomb treatments of the continuum, the results are qualitatively different. In excited electronic states, three electronic structure methods, TDDFT, ADC(2), and CASSCF, have been used for the computation of the Dyson orbitals, while the continuum was treated at the B-spline/DFT level. We show that photoionization observables are sensitive probes of the nature of the excited states as well as of the quality of excited state wave functions. This paves the way for applications in more complex situations such as time resolved photoionization spectroscopy.

  2. Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons

    NASA Astrophysics Data System (ADS)

    Gould, Charles

    Dans ce travail on utilise une nouvelle geometrie pour augmenter le controle sur le nombre d'electrons contenus dans une boite quantique laterale, et ainsi atteindre un regime de petit nombre d'electrons. Ces echantillons permettent une etude du blocage de Coulomb quand les electrons sont injectes a partir d'un gaz electronique a deux dimensions (2DEG). Les mesures a faible champ magnetique demontrent la grande flexibilite des echantillons et montrent que l'on peut faire varier le nombre d'electrons dans une boite quantique a partir de plus de 40 electrons jusqu'a un seul electron, ce qui est assez courant dans les boites quantiques verticales, mais ce qui n'avait jamais ete reussi dans une boite quantique laterale. Nos resultats montrent egalement que dans les boites quantiques laterales il est possible de determiner le spin du niveau qui participe au transport a l'aide du phenomene de blocage de spin. De plus, dans certaines circonstances il est meme possible de determiner le spin total de la boite quantique, ce qui peut avoir des applications pratiques dans des domaines tels l'informatique quantique. Les mesures dans le regime de renversement de spin a un champ magnetique plus eleve montrent l'importance des correlations electrons---electrons dans ces boites quantiques, qui menent a des depolarisations et a des structures de spins qui ont un effet sur le transport. En particulier, ces correlations menent a l'existence de niveaux excites de basse energie qui causent une dependance anormale de l'amplitude des pics de blocage de Coulomb en fonction de la temperature. Nos experiences demontrent egalement la possibilite d'utiliser ces boites quantiques comme sondes pour etudier les proprietes du bord d'un 2DEG. Une voie de recherche a etre exploree.

  3. Gravity duals for the Coulomb branch of marginally deformed Script N = 4 Yang-Mills

    NASA Astrophysics Data System (ADS)

    Hernández, Rafael; Sfetsos, Konstadinos; Zoakos, Dimitrios

    2006-03-01

    Supergravity backgrounds dual to a class of exactly marginal deformations of Script N = 4 supersymmetric Yang-Mills can be constructed through an SL(2,Bbb R) sequence of T-dualities and coordinate shifts. We apply this transformation to multicenter solutions and derive supergravity backgrounds describing the Coulomb branch of Script N = 1 theories at strong 't Hooft coupling as marginal deformations of Script N = 4 Yang-Mills. For concreteness we concentrate to cases with an SO(4) × SO(2) symmetry preserved by continuous distributions of D3-branes on a disc and on a three-dimensional spherical shell. We compute the expectation value of the Wilson loop operator and confirm the Coulombic behaviour of the heavy quark-antiquark potential in the conformal case. When the vev is turned on we find situations where a complete screening of the potential arises, as well as a confining regime where a linear or a logarithmic potential prevails depending on the ratio of the quark-antiquark separation to the typical vev scale. The spectra of massless excitations on these backgrounds are analyzed by turning the associated differential equations into Schrödinger problems. We find explicit solutions taking into account the entire tower of states related to the reduction of type-IIB supergravity to five dimensions, and hence we go beyond the s-wave approximation that has been considered before for the undeformed case. Arbitrary values of the deformation parameter give rise to the Heun differential equation and the related Inozemtsev integrable system, via a non-standard trigonometric limit as we explicitly demonstrate.

  4. Reconfiguration and Control of Non-Equal Mass Three-Craft Coulomb Formation

    NASA Astrophysics Data System (ADS)

    Ting, Wang; Guangqing, Xia; Nan, Zhao

    2016-03-01

    The paper studied reconfiguration of Coulomb formation from three-craft system to four-craft system. Assumed that three-craft Coulomb system already formed a triangle configuration, then, the fourth Coulomb craft is scheduled to join the existing system so as to form a new static configuration. New possible configurations such as quadrilateral in 2-dimension and tetrahedron in 3-dimension for four-craft Coulomb formation are discussed in the paper. The processing of reconfiguration will not change the original origin and triangle formation. Through the Particle Swarm Optimization (PSO) algorithm, the mass, the charge and the position of the fourth Coulomb craft can be calculated for these configurations.

  5. Ion wake effects on the Coulomb ion drag in complex dusty plasmas

    SciTech Connect

    Ki, Dae-Han; Jung, Young-Dae

    2010-09-06

    The ion wake effects on the Coulomb drag force are investigated in complex dusty plasmas. It is shown that the ion wake effects significantly enhance the Coulomb ion drag force. It is also found that the ion wake effects on the Coulomb drag force increase with an increase in the Debye length. In addition, the ion wake effects on the momentum transfer cross section and Coulomb drag force are found to be increased with increasing thermal Mach number, i.e., decreasing plasma temperature. It is also found that the Coulomb ion drag force would be stronger for smaller dust grains.

  6. Is the ground state of Yang-Mills theory Coulombic?

    SciTech Connect

    Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D.; Lutz, W.

    2008-08-01

    We study trial states modelling the heavy quark-antiquark ground state in SU(2) Yang-Mills theory. A state describing the flux tube between quarks as a thin string of glue is found to be a poor description of the continuum ground state; the infinitesimal thickness of the string leads to UV artifacts which suppress the overlap with the ground state. Contrastingly, a state which surrounds the quarks with non-Abelian Coulomb fields is found to have a good overlap with the ground state for all charge separations. In fact, the overlap increases as the lattice regulator is removed. This opens up the possibility that the Coulomb state is the true ground state in the continuum limit.

  7. Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene

    PubMed Central

    Mihnev, Momchil T.; Tolsma, John R.; Divin, Charles J.; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A.; MacDonald, Allan H.; Norris, Theodore B.

    2015-01-01

    In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron–phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport, even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied. PMID:26399955

  8. Characterization of ion Coulomb crystals for fundamental sciences

    NASA Astrophysics Data System (ADS)

    Okada, Kunihiro; Ichikawa, Masanari; Wada, Michiharu

    2015-11-01

    We performed classical molecular dynamics (MD) simulations in order to search the conditions for efficient sympathetic cooling of highly charged ions (HCIs) in a linear Paul trap. Small two-component ion Coulomb crystals consisting of laser-cooled ions and HCIs were characterized by the results of the MD simulations. We found that the spatial distribution is determined by not only the charge-to-mass ratio but also the space charge effect. Moreover, the simulation results suggest that the temperature of HCIs do not necessarily decrease with increasing the number of laser-cooled ions in the cases of linear ion crystals. We also determined the cooling limit of sympathetically cooled 165Ho14+ ions in small linear ion Coulomb crystals. The present results show that sub-milli-Kelvin temperatures of at least 10 Ho14+ ions will be achieved by sympathetic cooling with a single laser-cooled Be+.

  9. Stationary entanglement between two nanomechanical oscillators induced by Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Qin, Wu; Yin, Xiao; Zhi-Ming, Zhang

    2016-01-01

    We propose a scheme for entangling two nanomechanical oscillators by Coulomb interaction in an optomechanical system. We find that the steady-state entanglement of two charged nanomechanical oscillators can be obtained when the coupling between them is stronger than a critical value which relies on the detuning. Remarkably, the degree of entanglement can be controlled by the Coulomb interaction and the frequencies of the two charged oscillators. Project supported by the Major Research Plan of the National Natural Science Foundation of China (Grant No. 91121023), the National Natural Science Foundation of China (Grant Nos. 61378012, 60978009, and 11574092), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20124407110009), the National Basic Research Program of China (Grant Nos. 2011CBA00200 and 2013CB921804), and the Program for Changjiang Scholar and Innovative Research Team in University, China (Grant No. IRT1243).

  10. 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 ) .

  11. Conductance of a proximitized nanowire in the Coulomb blockade regime

    NASA Astrophysics Data System (ADS)

    van Heck, B.; Lutchyn, R. M.; Glazman, L. I.

    2016-06-01

    We identify the leading processes of electron transport across finite-length segments of proximitized nanowires and build a quantitative theory of their two-terminal conductance. In the presence of spin-orbit interaction, a nanowire can be tuned across the topological transition point by an applied magnetic field. Due to a finite segment length, electron transport is controlled by the Coulomb blockade. Upon increasing of the field, the shape and magnitude of the Coulomb blockade peaks in the linear conductance are defined, respectively, by Andreev reflection, single-electron tunneling, and resonant tunneling through the Majorana modes emerging after the topological transition. Our theory provides the framework for the analysis of experiments with proximitized nanowires [such as reported in S. M. Albrecht et al., Nature (London) 531, 206 (2016), 10.1038/nature17162] and identifies the signatures of the topological transition in the two-terminal conductance.

  12. Effect of Coulomb screening length on nuclear "pasta" simulations

    NASA Astrophysics Data System (ADS)

    Alcain, P. N.; Giménez Molinelli, P. A.; Nichols, J. I.; Dorso, C. O.

    2014-05-01

    We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semiclassical molecular dynamics model, studying isospin symmetric matter at subsaturation densities and low temperatures. The electrostatic interaction between protons is included as a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the nonhomogeneous nuclear structures known as "nuclear pasta." As the screening length increases, we can see a transition from a one-per-cell pasta regime (due exclusively to finite-size effects) to a more appealing multiple pasta per simulation box. This qualitative difference in the structure of neutron star matter at low temperatures shows that special caution should be taken when the screening length is estimated for numerical simulations.

  13. 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.

  14. Imaging Coulomb islands in a quantum Hall interferometer.

    PubMed

    Hackens, B; Martins, F; Faniel, S; Dutu, C A; Sellier, H; Huant, S; Pala, M; Desplanque, L; Wallart, X; Bayot, V

    2010-01-01

    In the quantum Hall regime, near integer filling factors, electrons should only be transmitted through spatially separated edge states. However, in mesoscopic systems, electronic transmission turns out to be more complex, giving rise to a large spectrum of magnetoresistance oscillations. To explain these observations, recent models put forward the theory that, as edge states come close to each other, electrons can hop between counterpropagating edge channels, or tunnel through Coulomb islands. Here, we use scanning gate microscopy to demonstrate the presence of QH Coulomb islands, and reveal the spatial structure of transport inside a QH interferometer. Locations of electron islands are found by modulating the tunnelling between edge states and confined electron orbits. Tuning the magnetic field, we unveil a continuous evolution of active electron islands. This allows to decrypt the complexity of high-magnetic-field magnetoresistance oscillations, and opens the way to further local-scale manipulations of QH localized states. PMID:20975700

  15. 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.

  16. Coulomb blockage of hybridization in two-dimensional DNA arrays

    NASA Astrophysics Data System (ADS)

    Vainrub, Arnold; Pettitt, B. Montgomery

    2002-10-01

    Experiments on DNA microarrays have revealed substantial differences in hybridization thermodynamics between DNA free in solution and surface tethered DNA. Here we develop a mean field model of the Coulomb effects in two-dimensional DNA arrays to understand the binding isotherms and thermal denaturation of the double helix. We find that the electrostatic repulsion of the assayed nucleic acid from the array of DNA probes dominates the binding thermodynamics, and thus causes the Coulomb blockage of the hybridization. The results explain, observed in DNA microarrays, the dramatic decrease of the hybridization efficiency and the thermal denaturation curve broadening as the probe surface density grows. We demonstrate application of the theory for evaluation and optimization of the sensitivity, specificity, and the dynamic range of DNA array devices.

  17. ``Perfect'' Coulomb Drag in a Bilayer Quantum Hall System

    NASA Astrophysics Data System (ADS)

    Nandi, D.; Finck, A. D. K.; Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.

    2012-02-01

    We report Coulomb drag measurements in Corbino geometry which reveal that equal but oppositely directed electrical currents can freely propagate across the insulating bulk of the bilayer quantized Hall state at νT=1 even when the two 2D layers are electrically isolated and interlayer tunneling has been heavily suppressed by an in-plane magnetic field. This effect, which we dub ``perfect'' Coulomb drag, reflects the transport of charge neutral excitons across the bulk of the 2D system. The equal magnitude of the drive and drag currents is lost at high current and when either the temperature or effective separation between the two 2D layers is increased. In each of these cases, ordinary quasiparticle charge transport across the annulus has grown to dominate over exciton transport.

  18. Structural phase transitions and topological defects in ion Coulomb crystals

    SciTech Connect

    Partner, Heather L.; Nigmatullin, Ramil; Burgermeister, Tobias; Keller, Jonas; Pyka, Karsten; Plenio, Martin B.; Retzker, Alex; Zurek, Wojciech Hubert; del Campo, Adolfo; Mehlstaubler, Tanja E.

    2014-11-19

    We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed non-adiabatically. For a second order phase transition, the Kibble-Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.

  19. 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.

  20. Simulation of Coulomb interaction effects in electron sources

    NASA Astrophysics Data System (ADS)

    Rouse, John; Zhu, Xieqing; Liu, Haoning; Munro, Eric

    2011-07-01

    Over many years, we have developed electron source simulation software that has been used widely in the electron optics community to aid the development of rotationally symmetric electron and ion guns. The simulation includes the modelling of cathode emission and the effects of volumetric space charge. In the present paper we describe the existing software and explain how we have extended this software to include the effects of discrete Coulomb interactions between the electrons as they travel from the cathode surface to the exit of the gun. In the paper, we will describe the numerical models we have employed, the techniques we have used to maximize the speed of the Coulomb force computation and present several illustrative examples of cases analyzed using the new software, including thermal field emitters, LaB 6 guns and flat dispenser-type cathodes.

  1. Coulomb's Law Corrections from a Gauge-Kinetic Mixing

    NASA Astrophysics Data System (ADS)

    Gaete, Patricio; Schmidt, Iván

    We study the connection or equivalence between two well-known extensions of the Standard Model, that is, for the coupling between the familiar massless electromagnetism U(1)QED and a hidden-sector U(1)h, and axionic electrodynamics. Our discussion is carried out using the gauge-invariant but path-dependent variables formalism, which is an alternative to the Wilson loop approach. When we compute in this way the static quantum potential for the coupling between the familiar massless electromagnetism U(1)QED and a hidden-sector U(1)h, the result of this calculation is a Yukawa correction to the usual static Coulomb potential. Previously,14, we have shown that axionic electrodynamics has a different structure which is reflected in a confining piece. Therefore, both extensions of the Standard Model are not equivalent. Interestingly, when the above calculation is done inside a superconducting box, the Coulombic piece disappears leading to a screening phase.

  2. 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.

  3. 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.

  4. Soft dipole excitations in 11Li

    NASA Astrophysics Data System (ADS)

    Esbensen, H.; Bertsch, G. F.

    1992-06-01

    A three-body model of 11Li is extended to include all interactions in unbound states in the continuum. We use a Green function technique to solve the three-body hamiltonian equation, and study the continuum dipole states produced by electromagnetic excitations of the ground state. The final-state interaction modifies the dipole strength function substantially, making it similar to an independent-particle strength function, but the total strength is enhanced by 50% due to ground-state correlations. The dipole strength is concentrated in a peak just above threshold, and the strength distribution is consistent with the measured beam energy dependence of the Coulomb dissociation cross section. This threshold peak also gives a narrow component in the neutron and the residual nucleus momentum distributions. The angular distributions of the neutrons emitted in Coulomb-induced reactions show a surprising anticorrelation, favoring emission with a large opening angle between the directions of the two neutrons in the rest frame of 11Li.

  5. Isotope separation by photodissociation of Van der Waal's molecules

    DOEpatents

    Lee, Yuan T.

    1977-01-01

    A method of separating isotopes based on the dissociation of a Van der Waal's complex. A beam of molecules of a Van der Waal's complex containing, as one partner of the complex, a molecular species in which an element is present in a plurality of isotopes is subjected to radiation from a source tuned to a frequency which will selectively excite vibrational motion by a vibrational transition or through electronic transition of those complexed molecules of the molecular species which contain a desired isotope. Since the Van der Waal's binding energy is much smaller than the excitational energy of vibrational motion, the thus excited Van der Waal's complex dissociate into molecular components enriched in the desired isotope. The recoil velocity associated with vibrational to translational and rotational relaxation will send the separated molecules away from the beam whereupon the product enriched in the desired isotope can be separated from the constituents of the beam.

  6. The role of the partner atom and resonant excitation energy in ICD in rare gas dimers

    NASA Astrophysics Data System (ADS)

    O'Keeffe, Patrick; Ripani, Enrico; Bolognesi, Paola; Coreno, Marcello; Avaldi, Lorenzo; Devetta, Michele; Callegari, Carlo; Di Praia, Michele; Prince, Kevin; Richter, Robert; Alagial, Michele; Kivimäkil, Antti

    2014-04-01

    We show experimental evidence for Interatomic Coulombic Decay (ICD) in mixed rare gas dimers following resonant Auger decay. A velocity map imaging apparatus together with a cooled supersonic beam containing Ar2, ArNe and ArKr dimers was used to record electron VMI images in coincidence with two mass selected ions following excitation on five resonances converging to the Ar+ 2p-11/2 and 2p-13/2 thresholds using the synchrotron radiation. The results show that the kinetic energy distribution of the ICD electrons observed in coincidence with the ions from Coulomb explosion of the dimers depends on the partner ion and resonant photon energy.

  7. Extended Kepler-Coulomb quantum superintegrable systems in three dimensions

    NASA Astrophysics Data System (ADS)

    Kalnins, E. G.; Kress, J. M.; Miller, W., Jr.

    2013-03-01

    The quantum Kepler-Coulomb system in three dimensions is well known to be second order superintegrable, with a symmetry algebra that closes polynomially under commutators. This polynomial closure is also typical for second order superintegrable systems in 2D and for second order systems in 3D with nondegenerate (four-parameter) potentials. However, the degenerate three-parameter potential for the 3D Kepler-Coulomb system (also second order superintegrable) is an exception, as its symmetry algebra does not close polynomially. The 3D four-parameter potential for the extended Kepler-Coulomb system is not even second order superintegrable, but Verrier and Evans (2008 J. Math. Phys. 49 022902) showed it was fourth order superintegrable, and Tanoudis and Daskaloyannis (2011 arXiv:11020397v1) showed that, if a second fourth order symmetry is added to the generators, the symmetry algebra closes polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider an infinite class of quantum extended Kepler-Coulomb three- and four-parameter systems indexed by a pair of rational numbers (k1, k2) and reducing to the usual systems when k1 = k2 = 1. We show these systems to be superintegrable of arbitrarily high order and determine the structure of their symmetry algebras. We demonstrate that the symmetry algebras close algebraically; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering operators, not themselves symmetry operators or even defined independent of basis, that can be employed to construct the symmetry operators and their structure relations.

  8. Stability characterizations of fixtured rigid bodies with Coulomb friction

    SciTech Connect

    PANG,J.S.; TRINKLE,JEFFREY C.

    2000-02-15

    This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.

  9. Electron screening of the Coulomb potential at small internuclear distances

    NASA Astrophysics Data System (ADS)

    Zinoviev, A. N.

    2015-07-01

    Values of He+-Au potential at small internuclear distances (R = 10-4 to 10-3 nm) have been obtained from the Rutherford backscattering (RBS) data. The potential has been shown to be independent of the collision velocity and close to the potential approximation proposed in Zinoviev (2011) [1]. Experimental data on the electron screening of the Coulomb potential enabled calculation of corrections for the nuclear fusion cross-sections and improvement of the RBS data quantitative analysis.

  10. 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.

  11. Coulomb interaction from the interplay between confinement and screening

    NASA Astrophysics Data System (ADS)

    Gaete, P.; Guendelman, E. I.

    2004-07-01

    It has been noticed that confinement effects can be described by the addition of a -FμνaFaμν term in the Lagrangian density. We now study the combined effect of such "confinement term" and that of a mass term. The surprising result is that the interplay between these two terms gives rise to a Coulomb interaction. Our picture has a certain correspondence with the quasiconfinement picture described by Giles, Jaffe and de Rujula for QCD with symmetry breaking.

  12. Coulomb field scattering in Born-Infeld electrodynamics

    SciTech Connect

    Tennant, Daniel

    2011-02-15

    In the context of Born-Infeld electrodynamics, the electromagnetic fields interact with each other via their nonlinear couplings. A calculation will be performed where an incoming electromagnetic plane wave scatters off a Coulomb field in the geometrical optics approximation. In addition to finding the first-order angle of deflection, exact solutions for the trajectory will also be found. The possibility of electromagnetic bound states will be discussed.

  13. The Role of Triaxiality in Shape-Coexistence in Light Krypton Isotopes

    NASA Astrophysics Data System (ADS)

    Fischer, S. M.; Lister

    2008-04-01

    Shape co-existence in lead^1 and krypton^2-4 isotopes has become a cutting-edge topic in understanding the structure of heavier nuclei. Prediction of the relative binding energies of different shapes, and understanding the mixing between configurations presents a discriminating challenge to nuclear theory. In ^72,74,76Kr the occurrence of two well bound shapes has been demonstrated through the observation of low-lying J^π = 0^+ isomers and through radioactive beam Coulomb excitation. Roughly speaking, the shapes correspond to oblate-like and prolate-like configurations. However, the exact shapes, and the role of triaxiality has yet to be fully explored. We present new results from ``in-beam'' heavy-ion spectroscopy on ^74Kr which shows that the population of the isomer is mainly through a gamma vibrational band and that considerable mixing is involved between the states built on the isomer and the gamma band. This research was supported by the DOE Office of Nuclear Physics under contract DE-AC02-06CH11357. ^1A. N. Andreyev et al., Nature 405, 430 (2000) ^2E. Clement et al., Phys. Rev. C 75, 054313 (2007) ^3E. Bouchez et al., Phys. Rev. Lett. 90, 082502 (2003) ^4M. Bender et al., Phys. Rev. C 74, 024312 (2006)

  14. Investigation into the semimagic nature of the tin isotopes through electromagnetic moments

    DOE PAGESBeta

    Allmond, J. M.; Stuchbery, A. E.; Galindo-Uribarri, A.; Padilla-Rodal, E.; Radford, D. C.; Batchelder, J. C.; Bingham, C. R.; Howard, M. E.; Liang, J. F.; Manning, B.; et al

    2015-10-19

    A complete set of electromagnetic moments, B(E2;0+1 2+1), Q(2+1), and g(2+1), have been measured from Coulomb excitation of semi-magic 112,114,116,118,120,122,124Sn (Z = 50) on natural carbon and titanium targets. The magnitude of the B(E2) values, measured to a precision of ~4%, disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed the Doppler- shift attenuation method. The B(E2) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q(2+1), has been measured for 114Sn. The static quadrupole moments are generallymore » consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The current theory calculations fail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at mid shell and outside of current model spaces, needs to be investigated in the future.« less

  15. Investigation into the semimagic nature of the tin isotopes through electromagnetic moments

    SciTech Connect

    Allmond, J. M.; Stuchbery, A. E.; Galindo-Uribarri, A.; Padilla-Rodal, E.; Radford, D. C.; Batchelder, J. C.; Bingham, C. R.; Howard, M. E.; Liang, J. F.; Manning, B.; Pain, S. D.; Stone, N. J.; Varner, R. L.; Yu, C. -H.

    2015-10-19

    A complete set of electromagnetic moments, B(E2;0+1 2+1), Q(2+1), and g(2+1), have been measured from Coulomb excitation of semi-magic 112,114,116,118,120,122,124Sn (Z = 50) on natural carbon and titanium targets. The magnitude of the B(E2) values, measured to a precision of ~4%, disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed the Doppler- shift attenuation method. The B(E2) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q(2+1), has been measured for 114Sn. The static quadrupole moments are generally consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The current theory calculations fail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at mid shell and outside of current model spaces, needs to be investigated in the future.

  16. Isotope separation by laser technology

    NASA Astrophysics Data System (ADS)

    Stoll, Wolfgang

    2002-03-01

    Isotope separation processes operate on very small differences, given either by the Quotient of masses with the same number of electrons or by their mass difference. When separating isotopes of light elements in mass quantities, thermodynamic processes accounting for the quotient, either in diffusion, chemical reactivity or distillation are used. For heavy elements those quotients are very small. Therefore they need a large number of separation steps. Large plants with high energy consumption result from that. As uranium isotope separation is the most important industrial field, alternatives, taking account for the mass difference, as e.g. gas centrifuges, have been developed. They use only a fraction of the energy input, but need a very large number of machines, as the individual throughput is small. Since it was discovered, that molecules of high symmetry like Uranium-Hexafluoride as a deep-cooled gas stream can be ionized by multiple photon excitation, this process was studied in detail and in competition to the selective ionization of metal vapors, as already demonstrated with uranium. The paper reports about the principles of the laser excitation for both processes, the different laboratory scale and prototypical plants built, the difficulties with materials, as far as the metal vapor laser separation is concerned, and the difficulties experienced in the similarity in molecular spectra. An overview of the relative economic merits of the different processes and the auspices in a saturated market for uranium isotope separation, together with other potential markets for molecular laser separation, is contained in the conclusions.

  17. Novel methods of copper vapor laser excitation

    SciTech Connect

    McColl, W.B.; Ching, H.; Bosch, R.; Brake, M.; Gilgenbach, R.

    1990-12-31

    Microwave and intense electron beam excitation of copper vapor are being investigated to be used in copper vapor lasers for isotope separation. Both methods use copper chloride vapor by heating copper chloride. Helium was used as the buffer gas at 2 to 100 torr. In the microwave system, intense copperlines at 510 nm and 578 nm were observed. Initial electron beam results indicate that light emission follows the beam current.

  18. 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.

  19. 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.

  20. Optimal reconfigurations of two-craft Coulomb formations along manifolds

    NASA Astrophysics Data System (ADS)

    Jones, Drew R.; Schaub, Hanspeter

    2013-02-01

    Coulomb formations refer to swarms of closely flying spacecraft, in which the net electric charge of each vehicle is controlled. Active charge control is central to this concept and enables a propulsion system with highly desirable characteristics, albeit with limited controllability. Numerous Coulomb formation equilibria have been derived, but to maintain and maneuver these configurations, some inertial thrust is required to supplement the nearly propellant-less charge control. In this work, invariant manifold theory is applied to two-craft Coulomb equilibria, which are admitted in a linearized two-body gravity model. The manifolds associated with these systems are analyzed for the first time, and are then utilized as part of a general procedure for formulating optimal reconfigurations. Specifically, uncontrolled flows along the manifolds are sought which provide near continuous transfers from one equilibrium to another. Control is then introduced to match continuity, while minimizing inertial thrusting. This methodology aims to exploit uncontrolled motions and charge control to realize the shape-changing ability of these formations, without large inertial control efforts. Some variations in formulating and parameterizing the optimal transfers are discussed, and analytical expressions are derived to aid in establishing control parameter limits, under certain assumptions. Numerical results are provided, as demonstrative examples of the optimization procedure, using relatively simple control approximations. Finally, Particle Swarm Optimization, a novel stochastic method, is used with considerable success to solve the numerically difficult parameter optimization problems.

  1. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule

    NASA Astrophysics Data System (ADS)

    Cloët, Ian C.; Bentz, Wolfgang; Thomas, Anthony W.

    2016-01-01

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q |≳0.5 GeV . The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei.

  2. Photoelectron wave function in photoionization: plane wave or Coulomb wave?

    PubMed

    Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I

    2015-11-19

    The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion. PMID:26509428

  3. Electron interactions in graphene through an effective Coulomb potential

    NASA Astrophysics Data System (ADS)

    Rodrigues, Joao N. B.; Adam, Shaffique

    A recent numerical work [H.-K. Tang et al, PRL 115, 186602 (2015)] considering graphene's π-electrons interacting through an effective Coulomb potential that is finite at short-distances, stressed the importance of the sp2 -electrons in determining the semimetal to Mott insulator phase transition in graphene. Some years ago, I. F. Herbut [PRL 97, 146401 (2006)] studied such a transition by mapping graphene's π-electrons into a Gross-Neveu model. From a different perspective, D. T. Son [PRB 75, 235423 (2007)] put the emphasis on the long-range interactions by modelling graphene as Dirac fermions interacting through a bare Coulomb potential. Here we build on these works and explore the phase diagram of Dirac fermions interacting through an effective Coulomb-like potential screened at short-distances. The interaction potential used allows for analytic results that controllably switch between the two perspectives above. This work was supported by the Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM medium-sized centre program) and by the Singapore Ministry of Education and Yale-NUS College (R-607-265-01312).

  4. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.

    PubMed

    Cloët, Ian C; Bentz, Wolfgang; Thomas, Anthony W

    2016-01-22

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q|≳0.5  GeV. The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei. PMID:26849589

  5. Coulomb crystal mass spectrometry in a digital ion trap

    NASA Astrophysics Data System (ADS)

    Deb, Nabanita; Pollum, Laura L.; Smith, Alexander D.; Keller, Matthias; Rennick, Christopher J.; Heazlewood, Brianna R.; Softley, Timothy P.

    2015-03-01

    We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radio-frequency wave form is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields are subsequently applied to the trap electrodes for ion ejection. Close to 100% detection efficiency is demonstrated for Ca+ and CaF+ ions from bicomponent Ca+-CaF+ Coulomb crystals prepared by the reaction of Ca+ with CH3F . A quantitative linear relationship is observed between ion number and the corresponding integrated time-of-flight (TOF) peak, independent of the ionic species. The technique is applicable to a diverse range of multicomponent Coulomb crystals—demonstrated here for Ca+-NH 3+ -NH 4+ and Ca+-CaOH +-CaOD + crystals—and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.

  6. 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.

  7. ISOTOPE SEPARATORS

    DOEpatents

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  8. Changes in the structure of nuclei between the magic neutron numbers 50 and 82 as indicated by a rotating-cluster analysis of the energy values of the first 2j excited states of isotopes of cadmium

    SciTech Connect

    Pauling, L.

    1981-09-01

    Values of R, the radius of rotation of the rotating cluster, are calculated from the observed values of the energy of the lowest 2/sup +/ states of the even isotopes of Cd, Sn, and Te with the assumption that the cluster is ..cap alpha.., pb, and ..cap alpha.., respectively. R shows a maximum at approx. N = 58, a minimum at approx. N = 62, and a second maximum at approx. N = 70. The increase to the first maximum is interpreted as resulting from the overcrowding of spherons (alphas and tritons) in the mantle (outer layer) of the nuclei, causing the cluster to change from rotating in the mantle to skimming over its surface; the decrease to the minimum results from the addition of three dineutrons to the core, expanding the mantle and permitting the rotating cluster to begin to drop back into it; and the increase to the second maximum results from the overcrowding of the larger mantle surrounding the core containing the semimagic number 14 of neutrons rather than the magic numbers 8 for N = 50. The decrease after the second maximum results from the further increase in the number of core neutrons to 20, corresponding to the magic number 82. Some additional evidence for the change to an intermediate structure between N = 50 and N = 82 is also discussed.

  9. A comparison of Coulomb and pseudo-Coulomb friction implementations: Application to the table contact phase of gymnastics vaulting.

    PubMed

    Jackson, M I; Hiley, M J; Yeadon, M R

    2011-10-13

    In the table contact phase of gymnastics vaulting both dynamic and static friction act. The purpose of this study was to develop a method of simulating Coulomb friction that incorporated both dynamic and static phases and to compare the results with those obtained using a pseudo-Coulomb implementation of friction when applied to the table contact phase of gymnastics vaulting. Kinematic data were obtained from an elite level gymnast performing handspring straight somersault vaults using a Vicon optoelectronic motion capture system. An angle-driven computer model of vaulting that simulated the interaction between a seven segment gymnast and a single segment vaulting table during the table contact phase of the vault was developed. Both dynamic and static friction were incorporated within the model by switching between two implementations of the tangential frictional force. Two vaulting trials were used to determine the model parameters using a genetic algorithm to match simulations to recorded performances. A third independent trial was used to evaluate the model and close agreement was found between the simulation and the recorded performance with an overall difference of 13.5%. The two-state simulation model was found to be capable of replicating performance at take-off and also of replicating key contact phase features such as the normal and tangential motion of the hands. The results of the two-state model were compared to those using a pseudo-Coulomb friction implementation within the simulation model. The two-state model achieved similar overall results to those of the pseudo-Coulomb model but obtained solutions more rapidly. PMID:21889150

  10. Theory of optical excitation of adsorbed rare gas atoms

    NASA Astrophysics Data System (ADS)

    Tsukada, Masaru; Brenig, Wilhelm

    1985-03-01

    Optical absorption spectra of rare-gas atoms adsorbed on metal surfaces exhibit a bimodal behavior, which, according to Cunningham, Greenlaw and Flynn, can be correlated with the difference I' - φ (where I' is the ionization energy of the excited (gas phase) state of the rare gas atom and φ the work function of the metal) controlling the energetics of charge transfer from the excited atom to the metal. In this paper we propose a model which allows to treat this charge transfer and some accompanying many-body effects in detail. Strong Coulomb attraction between the core hole and the excited electron on the adatom is taken into account as well as the interaction with surface plasmons. An improved charge transfer criterion is obtained which, besides the important parameter I∗ - φ, involves additional parameters such as the adsorbate-metal coupling strength and the plasmon frequency.

  11. A high-current electron beam ion trap as a charge breeder for the reacceleration of rare isotopes at the NSCL (invited)

    SciTech Connect

    Schwarz, S.; Bollen, G.; Kostin, M.; Marti, F.; Zavodszky, P.; Crespo Lopez-Urrutia, J. R.; Dilling, J.; Kester, O.

    2008-02-15

    Reacceleration of low-energy rare isotope beams available from gas stopping of fast-fragment beams or from an ISOL target station to energies in the range of 0.3-12 MeV/nucleon is needed for experiments such as low-energy Coulomb excitation and transfer reaction studies and for the precise study of astrophysical reactions. The implementation of charge breeding as a first step in a reaccelerator is a key to obtaining a compact and cost-efficient reacceleration scheme. For highest efficiency it is essential that single charge states are obtained in a short breeding time. A low-emittance beam must be delivered. An electron beam ion trap (EBIT) has the potential to meet these requirements. An EBIT-based charge breeder is presently under design and construction at the NSCL as part of the construction of a reaccelerator for stopped beams from projectile fragmentation. This new facility will have the potential to provide low-energy rare isotope beams not yet available elsewhere.

  12. Laser Isotope Enrichment for Medical and Industrial Applications

    SciTech Connect

    Leonard Bond

    2006-07-01

    repression. In this scheme a gas, of the selected isotopes for enrichment, is irradiated with a laser at a particular wavelength that would excite only one of the isotopes. The entire gas is subject to low temperatures sufficient to cause condensation on a cold surface. Those molecules in the gas that the laser excited are not as likely to condense as are the unexcited molecules. Hence the gas drawn out of the system will be enriched in the isotope that was excited by the laser. We have evaluated the relative energy required in this process if applied on a commercial scale. We estimate the energy required for laser isotope enrichment is about 20% of that required in centrifuge separations, and 2% of that required by use of "calutrons".

  13. Photodisintegration of Lithium Isotopes

    NASA Astrophysics Data System (ADS)

    Wurtz, Ward Andrew

    We have performed a measurement of the photodisintegration of the lithium isotopes, 6Li and 7Li, using a monochromatic, polarised photon beam and a segmented neutron detector array which covers approximately ¼ of 4pi srad. Using time-of-flight and scintillator light-output spectra we separate the data into individual reaction channels. This work is motivated by the need to compare with recent theoretical predictions and to provide data for future theoretical work. For the photodisintegration of 6Li we took data at 12 photon energies between 8 and 35 MeV. We describe the data using a model consisting of two-body reaction channels and obtain angular distributions and absolute cross sections for many of these reaction channels. We compare our results with a recent Lorentz integral transform calculation (Bacca et al. Phys. Rev. C 69, 057001 (2004)). Our results are in reasonable agreement with the calculation, in contradiction with previous experimental results. For the photodisintegration of 7Li, we took data at 9 photon energies between 10 and 35 MeV. We obtain cross sections for the reaction channel 7Li + gamma → n + 6 Li(g.s.) at all photon energies with angular distributions at all but the highest energy. We obtain angular distributions and total cross sections for reaction channels involving excited states of the daughter nucleus, 6Li, at select energies. We hope that these measurements will provide incentive for new theoretical calculations. We observe neutrons that can only be described by the reaction channel 7Li + gamma → n + 6Li(10.0) which necessitates an excited state of 6Li with excitation energy Ex = 10.0 +/- 0.5 MeV that is not in the standard tables of excited states. ii

  14. Livermore experience: contributions of J. H. Eberly to laser excitation theory

    SciTech Connect

    Shore, B W; Kulander, K; Davis, J I

    2000-10-12

    This article summarizes the developing understanding of coherent atomic excitation, as gained through a collaboration of J. H. Eberly with the Laser Isotope Separation Program of the Lawrence Livermore National Laboratory, particularly aspects of coherence, population trapping, multilevel multiphoton excitation sequences, analytic solutions to multistate excitation chains, the quasicontinuum, pulse propagation, and noise. In addition to the discovery of several curious and unexpected properties of coherent excitation, mentioned here, the collaboration provided an excellent example of unexpected benefits from investment into basic research.

  15. Investigation into the semimagic nature of the tin isotopes through electromagnetic moments

    NASA Astrophysics Data System (ADS)

    Allmond, J. M.; Stuchbery, A. E.; Galindo-Uribarri, A.; Padilla-Rodal, E.; Radford, D. C.; Batchelder, J. C.; Bingham, C. R.; Howard, M. E.; Liang, J. F.; Manning, B.; Pain, S. D.; Stone, N. J.; Varner, R. L.; Yu, C.-H.

    2015-10-01

    A complete set of electromagnetic moments, B (E 2 ;01+→21+) ,Q (21+) , and g (21+) , have been measured from Coulomb excitation of semimagic 112,114,116,118,120,122,124Sn (Z =50 ) on natural carbon and titanium targets. The magnitude of the B (E 2 ) values, measured to a precision of ˜4 % , disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011), 10.1016/j.physletb.2010.11.012] that employed the Doppler-shift attenuation method. The B (E 2 ) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q (21+) , has been measured for 114Sn. The static quadrupole moments are generally consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The g -factor measurements in Sn,114112 establish the recoil-in-vacuum method for states with τ ˜0.5 ps and hence demonstrate that this method can be used for future g -factor measurements on proton-rich isotopes toward 100Sn. Current theory calculations fail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at midshell and outside of current model spaces, needs to be investigated in the future.

  16. Direct and compound reactions induced by unstable helium beams near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Navin, A.; Tripathi, V.; Blumenfeld, Y.; Nanal, V.; Simenel, C.; Casandjian, J. M.; de France, G.; Raabe, R.; Bazin, D.; Chatterjee, A.; Dasgupta, M.; Kailas, S.; Lemmon, R. C.; Mahata, K.; Pillay, R. G.; Pollacco, E. C.; Ramachandran, K.; Rejmund, M.; Shrivastava, A.; Sida, J. L.; Tryggestad, E.

    2004-10-01

    Reactions induced by radioactive 6,8 He beams from the SPIRAL facility were studied on 63,65 Cu and 188,190,192 Os targets and compared to reactions with the stable 4He projectiles from the Mumbai Pelletron. Partial residue cross sections for fusion and neutron transfer obtained from the measured intensities of characteristic in-beam γ rays for the 6He + 63,65 Cu systems are presented. Coincidence measurements of heavy reaction products, identified by their characteristic γ rays, with projectilelike charged particles, provide direct evidence for a large transfer cross section with Borromean nuclei 6He at 19.5 and 30 MeV and 8He at 27 MeV. Reaction cross sections were also obtained from measured elastic angular distributions for 6,8 He +Cu systems. Cross sections for fusion and direct reactions with 4,6 He beams on heavier targets of 188,192 Os at 30 MeV are also presented. The present work underlines the need to distinguish between various reaction mechanisms leading to the same products before drawing conclusions about the effect of weak binding on the fusion process. The feasibility of extracting small cross sections from inclusive in-beam γ -ray measurements for reaction studies near the Coulomb barrier with low intensity isotope separation on-line beams is highlighted.

  17. Direct and compound reactions induced by unstable helium beams near the Coulomb barrier

    SciTech Connect

    Navin, A.; Tripathi, V.; Chatterjee, A.; Kailas, S.; Mahata, K.; Ramachandran, K.; Shrivastava, A.; Blumenfeld, Y.; Tryggestad, E.; Nanal, V.; Pillay, R.G.; Simenel, C.; Casandjian, J.M.; France, G. de; Rejmund, M.; Raabe, R.; Pollacco, E.C.; Sida, J.L.; Dasgupta, M.

    2004-10-01

    Reactions induced by radioactive {sup 6,8}He beams from the SPIRAL facility were studied on {sup 63,65}Cu and {sup 188,190,192}Os targets and compared to reactions with the stable {sup 4}He projectiles from the Mumbai Pelletron. Partial residue cross sections for fusion and neutron transfer obtained from the measured intensities of characteristic in-beam {gamma} rays for the {sup 6}He+{sup 63,65}Cu systems are presented. Coincidence measurements of heavy reaction products, identified by their characteristic {gamma} rays, with projectilelike charged particles, provide direct evidence for a large transfer cross section with Borromean nuclei {sup 6}He at 19.5 and 30 MeV and {sup 8}He at 27 MeV. Reaction cross sections were also obtained from measured elastic angular distributions for {sup 6,8}He+Cu systems. Cross sections for fusion and direct reactions with {sup 4,6}He beams on heavier targets of {sup 188,192}Os at 30 MeV are also presented. The present work underlines the need to distinguish between various reaction mechanisms leading to the same products before drawing conclusions about the effect of weak binding on the fusion process. The feasibility of extracting small cross sections from inclusive in-beam {gamma}-ray measurements for reaction studies near the Coulomb barrier with low intensity isotope separation on-line beams is highlighted.

  18. Acoustically excited heated jets. 1: Internal excitation

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

    1988-01-01

    The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

  19. Laser-induced separation of hydrogen isotopes in the liquid phase

    DOEpatents

    Freund, Samuel M.; Maier, II, William B.; Beattie, Willard H.; Holland, Redus F.

    1980-01-01

    Hydrogen isotope separation is achieved by either (a) dissolving a hydrogen-bearing feedstock compound in a liquid solvent, or (b) liquefying a hydrogen-bearing feedstock compound, the liquid phase thus resulting being kept at a temperature at which spectral features of the feedstock relating to a particular hydrogen isotope are resolved, i.e., a clear-cut isotope shift is delineated, irradiating the liquid phase with monochromatic radiation of a wavelength which at least preferentially excites those molecules of the feedstock containing a first hydrogen isotope, inducing photochemical reaction in the excited molecules, and separating the reaction product containing the first isotope from the liquid phase.

  20. Shells Evolution and Core Excitations in Semi-Magic Nuclei

    NASA Astrophysics Data System (ADS)

    Nowacki, F.

    2007-04-01

    Recent advances in Large Shell Model calculations allow now to treat extended valence spaces and more complete descriptions of (semi-)magic nuclei can be achieved with inclusion of core excitations. The interplay between shell evolution and core excitations in semi-magic nuclei will be illustrated for tin isotopic chains in the framework of Large Shell Model calculations. pn and nn monopole relative influence will be traced back on Effective Single Particle Energies and B(E2)'s.

  1. Nuclear fission fragment excitation of electronic transition laser media

    NASA Technical Reports Server (NTRS)

    Lorents, D. C.; Mccusker, M. V.; Rhodes, C. K.

    1976-01-01

    Specific characteristics of the media including density, excitation rates, wavelength, kinetics, fissile material, scale size, and medium uniformity are assessed. The use of epithermal neutrons, homogeneously mixed fissile material, and special high cross section nuclear isotopes to optimize coupling of the energy to the medium are shown to be important considerations maximizing the scale size, energy deposition, and medium uniformity. It is demonstrated that e-beam excitation can be used to simulate nuclear pumping conditions to facilitate the search for candidate media.

  2. Coulombic wall slip of concentrated soft-particle suspensions

    NASA Astrophysics Data System (ADS)

    Adams, Michael; Liu, Wei; Zhang, Zhibing; Fryer, Peter

    2013-06-01

    The coefficients of friction of concentrated soft-particle suspensions (tomato paste and a microgel suspension) were measured as a function of the slip velocity for a number of substrates. The data are interpreted using a micro-elastohydrodynamic model that is consistent with significant bulk frictional dissipation and an increase in the number of particle-wall contacts with increasing normal stress. The origin of the Coulombic slip, which has not been observed previously for pastes, is ascribed to the sensitivity of the lubricating film thickness.

  3. 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

  4. A proposal for Coulomb assisted laser cooling of piezoelectric semiconductors

    NASA Astrophysics Data System (ADS)

    Nia, Iman Hassani; Mohseni, Hooman

    2014-07-01

    Anti-Stokes laser cooling of semiconductors as a compact and vibration-free method is very attractive. While it has achieved significant milestones, increasing its efficiency is highly desirable. The main limitation is the lack of the pristine material quality with high luminescence efficiency. Here, we theoretically demonstrate that the Coulomb interaction among electrons and holes in piezoelectric heterostructures could lead to coherent damping of acoustic phonons; rendering a significantly higher efficiency that leads to the possibility of cooling a broad range of semiconductors.

  5. 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.

  6. A proposal for Coulomb assisted laser cooling of piezoelectric semiconductors

    SciTech Connect

    Nia, Iman Hassani; Mohseni, Hooman

    2014-07-28

    Anti-Stokes laser cooling of semiconductors as a compact and vibration-free method is very attractive. While it has achieved significant milestones, increasing its efficiency is highly desirable. The main limitation is the lack of the pristine material quality with high luminescence efficiency. Here, we theoretically demonstrate that the Coulomb interaction among electrons and holes in piezoelectric heterostructures could lead to coherent damping of acoustic phonons; rendering a significantly higher efficiency that leads to the possibility of cooling a broad range of semiconductors.

  7. 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

  8. Superconductor-insulator transition in the presence of Coulomb disorder

    NASA Astrophysics Data System (ADS)

    Shklovskii, B. I.

    2007-12-01

    Superconductor-insulator transition driven by the decreasing concentration of electrons n is studied in the case of the disorder potential created by randomly positioned charged impurities. Electrons and Cooper pairs (formed by a non-Coulomb attraction) nonlinearly screen the random potential of impurities. Both electrons and Cooper pairs can be delocalized or localized in the resulting self-consistent potential. The border separating the superconductor and insulator phases in the plane of the concentration of electrons and the length of the Cooper pair is found. For a strong disorder, the central segment of this border follows the Bose-Einstein-Condensation-BCS crossover line defined for a clean sample.

  9. A nonlinear Bloch model for Coulomb interaction in quantum dots

    SciTech Connect

    Bidegaray-Fesquet, Brigitte Keita, Kole

    2014-02-15

    In this paper, we first derive a Coulomb Hamiltonian for electron–electron interaction in quantum dots in the Heisenberg picture. Then we use this Hamiltonian to enhance a Bloch model, which happens to be nonlinear in the density matrix. The coupling with Maxwell equations in case of interaction with an electromagnetic field is also considered from the Cauchy problem point of view. The study is completed by numerical results and a discussion about the advisability of neglecting intra-band coherences, as is done in part of the literature.

  10. "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

  11. 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.

  12. 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

  13. Heavy quarks, gluons and the confinement potential in Coulomb gauge

    NASA Astrophysics Data System (ADS)

    Popovici, Carina; Watson, Peter; Reinhardt, Hugo

    2011-05-01

    We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.

  14. Heavy quarks, gluons and the confinement potential in Coulomb gauge

    SciTech Connect

    Popovici, Carina; Watson, Peter; Reinhardt, Hugo

    2011-05-23

    We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.

  15. 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.

  16. Interatomic Coulombic Decay Effects in Theoretical DNA Recombination Systems Involving Protein Interaction Sites

    NASA Astrophysics Data System (ADS)

    Vargas, E. L.; Rivas, D. A.; Duot, A. C.; Hovey, R. T.; Andrianarijaona, V. M.

    2015-03-01

    DNA replication is the basis for all biological reproduction. A strand of DNA will ``unzip'' and bind with a complimentary strand, creating two identical strands. In this study, we are considering how this process is affected by Interatomic Coulombic Decay (ICD), specifically how ICD affects the individual coding proteins' ability to hold together. ICD mainly deals with how the electron returns to its original state after excitation and how this affects its immediate atomic environment, sometimes affecting the connectivity between interaction sites on proteins involved in the DNA coding process. Biological heredity is fundamentally controlled by DNA and its replication therefore it affects every living thing. The small nature of the proteins (within the range of nanometers) makes it a good candidate for research of this scale. Understanding how ICD affects DNA molecules can give us invaluable insight into the human genetic code and the processes behind cell mutations that can lead to cancer. Authors wish to give special thanks to Pacific Union College Student Senate in Angwin, California, for their financial support.

  17. Thermonuclear reaction S30(p,γ)Cl31 studied via Coulomb breakup of Cl31

    NASA Astrophysics Data System (ADS)

    Langer, C.; Lepyoshkina, O.; Aksyutina, Y.; Aumann, T.; Novo, S. Beceiro; Benlliure, J.; Boretzky, K.; Chartier, M.; Cortina, D.; Pramanik, U. Datta; Ershova, O.; Geissel, H.; Gernhäuser, R.; Heil, M.; Ickert, G.; Johansson, H. T.; Jonson, B.; Kelić-Heil, A.; Klimkiewicz, A.; Kratz, J. V.; Krücken, R.; Kulessa, R.; Larsson, K.; Le Bleis, T.; Lemmon, R.; Mahata, K.; Marganiec, J.; Nilsson, T.; Panin, V.; Plag, R.; Prokopowicz, W.; Reifarth, R.; Ricciardi, V.; Rossi, D. M.; Schwertel, S.; Simon, H.; Sümmerer, K.; Streicher, B.; Taylor, J.; Vignote, J. R.; Wamers, F.; Wimmer, C.; Wu, P. Z.

    2014-03-01

    Coulomb breakup at high energy in inverse kinematics of proton-rich Cl31 was used to constrain the thermonuclear S30(p ,γ)Cl31 capture reaction rate under typical Type I x-ray burst conditions. This reaction is a bottleneck during rapid proton-capture nucleosynthesis (rp process), where its rate depends predominantly on the nuclear structure of Cl31. Two low-lying states just above the proton-separation threshold of Sp=296(50) keV in Cl31 have been identified experimentally using the R3B-LAND setup at the GSI Helmholtzzentrum für Schwerionenforschung GmbH. Both states are considered to play a key role in the thermonuclear S30(p ,γ)Cl31 capture reaction. Excitation energies of the first Jπ=1/2+,5/2+ states have been extracted and the reaction rate for proton capture on S30 under typical rp-process temperatures has been investigated.

  18. Elementary excitations in homogeneous superfluid neutron star matter: Role of the proton component

    SciTech Connect

    Baldo, Marcello; Ducoin, Camille

    2011-09-15

    The thermal evolution of neutron stars depends on the elementary excitations affecting the stellar matter. In particular, the low-energy excitations, whose energy is proportional to the transferred momentum, can play a major role in the emission and propagation of neutrinos. In this paper, we focus on the density modes associated with the proton component in the homogeneous matter of the outer core of neutron stars (at density between one and three times the nuclear saturation density, where the baryonic constituents are expected to be neutrons and protons). In this region, it is predicted that the protons are superconducting. We study the respective roles of the proton pairing and Coulomb interaction in determining the properties of the modes associated with the proton component. This study is performed in the framework of the random phase approximation, generalized in order to describe the response of a superfluid system. The formalism we use ensures that the generalized Ward's identities are satisfied. An important conclusion of this work is the presence of a pseudo-Goldstone mode associated with the superconducting protons in neutron-star matter. Indeed, the Goldstone mode, which characterizes a pure superfluid, is suppressed in usual superconductors because of the long-range Coulomb interaction, which allows a plasmon mode. However, for the proton component of stellar matter, the Coulomb field is screened by the electrons and a pseudo-Goldstone mode occurs, with a velocity increased by the Coulomb interaction.

  19. 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

  20. 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

  1. 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.

  2. Gauge equivalence in QCD: The Weyl and Coulomb gauges

    NASA Astrophysics Data System (ADS)

    Haller, Kurt; Ren, Hai-Cang

    2003-10-01

    The Weyl-gauge (Aa0=0) QCD Hamiltonian is unitarily transformed to a representation in which it is expressed entirely in terms of gauge-invariant quark and gluon fields. In a subspace of gauge-invariant states we have constructed that implement the non-Abelian Gauss’s law, this unitarily transformed Weyl-gauge Hamiltonian can be further transformed and, under appropriate circumstances, can be identified with the QCD Hamiltonian in the Coulomb gauge. We demonstrate an isomorphism that materially facilitates the application of this Hamiltonian to a variety of physical processes, including the evaluation of S-matrix elements. This isomorphism relates the gauge-invariant representation of the Hamiltonian and the required set of gauge-invariant states to a Hamiltonian of the same functional form but dependent on ordinary unconstrained Weyl-gauge fields operating within a space of “standard” perturbative states. The fact that the gauge-invariant chromoelectric field is not Hermitian has important implications for the functional form of the Hamiltonian finally obtained. When this non-Hermiticity is taken into account, the “extra” vertices in the Christ-Lee’ Coulomb-gauge Hamiltonian are natural outgrowths of the formalism. When this non-Hermiticity is neglected, the Hamiltonian used in the earlier work of Gribov and others results.

  3. 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.

  4. 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

  5. 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.

  6. 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

  7. Enhancement of the Coulomb collision rate by individual particle wakes

    NASA Astrophysics Data System (ADS)

    Baalrud, Scott; Scheiner, Brett

    2013-09-01

    Charged particles moving in a plasma leave a trailing wake in their electric potential profile associated with the response function of the medium. For superthermal particles, these wakes can cause significant departures from the oft-assumed screened Coulomb potential profile. The wakes extend the interaction length scale beyond the Debye screening length for collisions between fast test particles and field particles in their wake. This can increase the Coulomb collision rate for velocities beyond the thermal speed. To demonstrate this effect, we consider the relaxation rate due to electron-electron collisions of an electron distribution function with initially depleted tails, as is common near boundary sheaths or double layers. This problem is related to Langmuir's paradox. We compare the standard Landau (Fokker-Planck) collision operator, which does not account for wakes, with the Lenard-Balescu collision operator, which includes wake effects through the linear dielectric response function. For this distribution, the linear dielectric is described by the incomplete plasma dispersion function. We compare the collision operators directly as well as the relaxation rate determined from a hybrid kinetic-fluid model. S. D. Baalrud, Phys. Plasmas 20, 012118 (2013).

  8. Pore fluid pressure, apparent friction, and Coulomb failure

    USGS Publications Warehouse

    Beeler, N.M.; Simpson, R.W.; Hickman, S.H.; Lockner, D.A.

    2000-01-01

    Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of both friction and pore pressure, but is a material constant only if changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the potential failure plane. Although specific models of fault zones permit such a relation, neither is it known that fault zones within the Earth behave this way, nor is this behavior expected in all cases. In contrast, for an isotropic homogeneous poroelastic model the pore pressure changes are proportional to changes in mean stress, μ′ is not a material constant, and −∞ ≤ μ′ ≤ +∞. Analysis of the change in Coulomb failure stress for tectonically loaded reverse and strike-slip faults shows considerable differences between these two pore pressure models, suggesting that such models might be distinguished from one another using observations of triggered seismicity (e.g., aftershocks). We conclude that using the constant apparent friction model exclusively in studies of Coulomb failure stress is unwise and could lead to significant errors in estimated stress change and seismic hazard.

  9. 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.

  10. Mechanical model of the Lorentz force and Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Dmitriyev, Valery

    2008-09-01

    The centripetal and Coriolis accelerations experienced by a cart traveling over a rotating turntable are usually calculated proceeding from the known kinematics of the problem. Respective forces can be regarded as due to the entrainment of the cart in the moving solid environs. We extend the approach to the general case of a particle entrained in the flow of the surrounding medium. The expression for the driving force on the particle obtained from the kinematics of the entrainment prescribed appears to be isomorphic to the Lorentz and Coulomb force on a positive electric charge. The inverse direction of the electromagnetic force on a negative charge implies that a growing applied flow induces the upstream motion of the particle. A possible microscopic mechanism for it may be the Magnus force dynamics of a kink in a vortex tangle. The loop on a straight vortex filament can be taken as a model of the electron, the loop with a cavitation models the positron. The Lorentz force is concerned with the Coriolis acceleration. The Coulomb interaction is due to the centripetal or centrifugal force that arises in the turbophoresis of the kink in the perturbation field generated in the medium by the center of pressure.

  11. Exact linearized Coulomb collision operator in the moment expansion

    DOE PAGESBeta

    Ji, Jeong -Young; Held, Eric D.

    2006-10-05

    In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collisionmore » operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Furthermore, useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.« less

  12. Coulomb Stress Accumulation along the San Andreas Fault System

    NASA Technical Reports Server (NTRS)

    Smith, Bridget; Sandwell, David

    2003-01-01

    Stress accumulation rates along the primary segments of the San Andreas Fault system are computed using a three-dimensional (3-D) elastic half-space model with realistic fault geometry. The model is developed in the Fourier domain by solving for the response of an elastic half-space due to a point vector body force and analytically integrating the force from a locking depth to infinite depth. This approach is then applied to the San Andreas Fault system using published slip rates along 18 major fault strands of the fault zone. GPS-derived horizontal velocity measurements spanning the entire 1700 x 200 km region are then used to solve for apparent locking depth along each primary fault segment. This simple model fits remarkably well (2.43 mm/yr RMS misfit), although some discrepancies occur in the Eastern California Shear Zone. The model also predicts vertical uplift and subsidence rates that are in agreement with independent geologic and geodetic estimates. In addition, shear and normal stresses along the major fault strands are used to compute Coulomb stress accumulation rate. As a result, we find earthquake recurrence intervals along the San Andreas Fault system to be inversely proportional to Coulomb stress accumulation rate, in agreement with typical coseismic stress drops of 1 - 10 MPa. This 3-D deformation model can ultimately be extended to include both time-dependent forcing and viscoelastic response.

  13. 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

  14. "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

  15. "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

  16. Optical-response properties in levitated optomechanical systems beyond the low-excitation limit

    NASA Astrophysics Data System (ADS)

    Nie, Wenjie; Chen, Aixi; Lan, Yueheng

    2016-02-01

    We investigate the optical-response properties of a levitated optomechanical cavity coupled to a higher order excited atomic medium. The cavity field driven through the atom-field interaction is responsible for trapping a dielectric nanosphere, whose steady-state position is biased by the Coulomb force between the nanosphere and the cavity wall. We show that the phenomena of optomechanically induced transparency (OMIT) and amplification can be generated from the output probe field in the presence of an effective optomechanical coupling between the nanosphere and the cavity field. Further, the width of the transparency window increases with increasing strength of the effective optomechanical coupling, which is controlled easily by varying the Coulomb interaction and the radius of the nanosphere. In particular, when the higher order excitation of the atomic medium is included, a large driving of the atomic ensemble but a relatively small atom-field detuning can be applied to help observe the OMIT behavior in the hybrid system.

  17. Plasma-screening effects on the electron-impact excitation of hydrogenic ions in dense plasmas

    NASA Technical Reports Server (NTRS)

    Jung, Young-Dae

    1993-01-01

    Plasma-screening effects are investigated on electron-impact excitation of hydrogenic ions in dense plasmas. Scaled cross sections Z(exp 4) sigma for 1s yields 2s and 1s yields 2p are obtained for a Debye-Hueckel model of the screened Coulomb interaction. Ground and excited bound wave functions are modified in the screened Coulomb potential (Debye-Hueckel model) using the Ritz variation method. The resulting atomic wave functions and their eigenenergies agree well with the numerical and high-order perturbation theory calculations for the interesting domain of the Debye length not less than 10. The Born approximation is used to describe the continuum states of the projectile electron. Plasma screening effects on the atomic electrons cannot be neglected in the high-density cases. Including these effects, the cross sections are appreciably increased for 1s yields 2s transitions and decreased for 1s yields 2p transitions.

  18. Method for enriching a middle isotope using vibration-vibration pumping

    DOEpatents

    Rich, Joseph W.; Homicz, Gregory F.; Bergman, Richard C.

    1989-01-01

    Method for producing isotopically enriched material by vibration-vibration excitation of gaseous molecules wherein a middle mass isotope of an isotopic mixture including lighter and heavier mass isotopes preferentially populates a higher vibrational mode and chemically reacts to provide a product in which it is enriched. The method can be used for vibration-vibration enrichment of .sup.17 O in a CO reactant mixture.

  19. Isomeric States and Collective Excitations of Heaviest Nuclei

    NASA Astrophysics Data System (ADS)

    Adamian, G. G.; Antonenko, N. V.; Jolos, R. V.; Kuzmina, A. N.; Malov, L. A.; Shirikova, N. Yu.; Sushkov, A. V.

    2013-03-01

    The isotopic dependence of two-quasiparticle isomeric states in Fm and No is treated. An α-decay chain through the isomeric states of super-heavy nuclei is demonstrated. The excitation energies and the structure of the low lying states with Kπ = 0‒ 1‒ 2‒ are calculated with the quasiparticle phonon model.

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

    NASA Astrophysics Data System (ADS)

    Barghouthi, I.; Barakat, A.

    2003-04-01

    Because of its relevance to the solar wind and terrestrial polar wind, we investigated the problem where a swarm of minor ions escaped through a background of non-uniform major ions. The Fokker-Planck expression was used to represent the Coulomb collisions between the minor and major ions. A change of variables was utilized in order to transform the problem into a simpler form where the background medium was uniform. This transformed problem described minor ions diffusing through a background of ions of a constant density in the semi-infinite region (z>0), and vacuum in the region (z<0), which resembles the standard Milne problem. A Monte Carlo model was used to investigate this "generalized Coulomb Milne" problem for three different minor-to-major ion mass ratios, namely; R = m/M = 1/16, 1 and 16, where m and M are the minor and major ion masses, respectively. The minor ions' velocity distribution function and velocity moments (i.e. density, drift velocity, parallel and perpendicular temperatures, and parallel and perpendicular heat fluxes) were computed. The following conclusions can be drawn: (1) In general, the minor ion species for the cases of (R=1,16) show very similar characteristics, while the third case (R=1/16) shows very different characteristics. (2) In the collision-dominated region (z>>1), the gradient of the normalized density profile approaches a constant value. This asymptotic value of the gradient increases when R decreases. (3) As the minor ion species drifts from the collision-dominated region (z>>) to the collisionless region (z<<1), its velocity distribution starts as Maxwellian, then it develops a tail in the (-z) direction, and finally reaches a form close to bi-Maxwellian. The case of (R=1/16) develops a relatively more pronounced tail, and displays a double-hump form, which is absent for the other two cases. (4) The heat flux profile for the case of (R=1/6) in the collision-dominated region exceeds the corresponding values from the other

  1. Evolution of the mixed-symmetry 2{sup+}{sub 1,ms} quadrupole-photon excitation from spherical to {gamma}-soft Xe nuclei.

    SciTech Connect

    Coquard, L.; Pietralla, N.; Rainovski, G.; Ahn, T.; Bettermann, L.; Carpenter, M. P.; Janssens, R.V. F.; Leske, J.; Lister, C. J.; Moller, O.; Rother, W.; Werner, V.; Zhu, S.

    2010-08-23

    Low-lying collective states of {sup 130,132}Xe have been investigated by {gamma}-ray spectroscopy following {sup 12}C(Xe,Xe*){sup 12}C projectile Coulomb excitation. The one-phonon 2{sub 1,ms}{sup +} states have been identified: the 2{sub 4}{sup +} state at 2150 keV with B(M1;2{sub 4}{sup +} {yields} 2{sub 1}{sup +})=0.15(4){mu}{sub {mu}}{sup N} in {sup 130}Xe and the 2{sub 3}{sup +} state at 1985 keV with B(M1;2{sub 3}{sup +} {yields} 2{sub 1}{sup +})=0.22(6){mu}{sub N}{sup 2} in {sup 132}Xe. The evolution of the one-phonon 2{sub 1,ms}{sup +} states in the even-even stable xenon isotopic chain from the vibrators near N=82 to the {gamma}-soft nuclei toward midshell is discussed.

  2. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, Karl F.; Haynam, Christopher A.; Johnson, Michael A.; Worden, Earl F.

    1999-01-01

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207.

  3. Atomic vapor laser isotope separation of lead-210 isotope

    DOEpatents

    Scheibner, K.F.; Haynam, C.A.; Johnson, M.A.; Worden, E.F.

    1999-08-31

    An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207. 5 figs.

  4. RESONANT CAVITY EXCITATION SYSTEM

    DOEpatents

    Baker, W.R.

    1959-08-01

    A cavity excitation circuit is described for rapidly building up and maintaining high-level oscillations in a resonant cavity. The circuit overcomes oscillation buildup slowing effects such as ion locking in the cavity by providing for the selective application of an amplified accelerating drive signal to the main cavity exciting oscillator during oscillation buildup and a direct drive signal to the oscillator thereafter.

  5. Derivation of capture cross sections from quasi-elastic excitation functions

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Gomes, P. R. S.

    2013-04-01

    The relationship between the quasi-elastic excitation function and the capture cross section is derived. The quasi-elastic data is shown to be a useful tool to extract the capture cross sections and the angular momenta of the captured systems for the reactions 16O+144,154Sm,208Pb, 20Ne+208Pb, and 32S+90,96Zr near and above the Coulomb barrier energies.

  6. 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.

  7. Dynamics of Coulomb correlations in semiconductors in high magnetic fields

    SciTech Connect

    Fromer, Neil Alan

    2002-05-01

    Current theories have been successful in explaining many nonlinear optical experiments in undoped semiconductors. However, these theories require a ground state which is assumed to be uncorrelated. Strongly correlated systems of current interest, such as a two dimensional electron gas in a high magnetic field, cannot be explained in this manner because the correlations in the ground state and the low energy collective excitations cause a breakdown of the conventional techniques. We perform ultrafast time-resolved four-wave mixing on $n$-modulation doped quantum wells, which contain a quasi-two dimensional electron gas, in a large magnetic field, when only a single Landau level is excited and also when two levels are excited together. We find evidence for memory effects and as strong coupling between the Landau levels induced by the electron gas. We compare our results with simulations based on a new microscopic approach capable of treating the collective effects and correlations of the doped electrons, and find a good qualitative agreement. By looking at the individual contributions to the model, we determine that the unusual correlation effects seen in the experiments are caused by the scattering of photo-excited electron-hole pairs with the electron gas, leading to new excited states which are not present in undoped semiconductors, and also by exciton-exciton interactions mediated by the long-lived collective excitations of the electron gas, inter-Landau level magnetoplasmons.

  8. Spatial periphery of lithium isotopes

    SciTech Connect

    Galanina, L. I. Zelenskaja, N. S.

    2013-12-15

    The spatial structure of lithium isotopes is studied with the aid of the charge-exchange and (t, p) reactions on lithium nuclei. It is shown that an excited isobaric-analog state of {sup 6}Li (0{sup +}, 3.56MeV) has a halo structure formed by a proton and a neutron, that, in the {sup 9}Li nucleus, there is virtually no neutron halo, and that {sup 11}Li is a Borromean nucleus formed by a {sup 9}Li core and a two-neutron halo manifesting itself in cigar-like and dineutron configurations.

  9. Addendum to 'Equation of state of classical Coulomb plasma mixtures'

    SciTech Connect

    Potekhin, A. Y.; Chabrier, G.; Chugunov, A. I.; DeWitt, H. E.; Rogers, F. J.

    2009-10-15

    Recently developed analytic approximation for the equation of state of fully ionized nonideal electron-ion plasma mixtures [A. Y. Potekhin, G. Chabrier, and F. J. Rogers, Phys. Rev. E 79, 016411 (2009)], which covers the transition between the weak and strong Coulomb coupling regimes and reproduces numerical results obtained in the hypernetted-chain (HNC) approximation, is modified in order to fit the small deviations from the linear mixing in the strong-coupling regime, revealed by recent Monte Carlo simulations. In addition, a mixing rule is proposed for the regime of weak coupling, which generalizes post-Debye density corrections to the case of mixtures and numerically agrees with the HNC approximation in that regime.

  10. Investigation of uncertainty components in Coulomb blockade thermometry

    SciTech Connect

    Hahtela, O. M.; Heinonen, M.; Manninen, A.; Meschke, M.; Savin, A.; Pekola, J. P.; Gunnarsson, D.; Prunnila, M.; Penttilä, J. S.; Roschier, L.

    2013-09-11

    Coulomb blockade thermometry (CBT) has proven to be a feasible method for primary thermometry in every day laboratory use at cryogenic temperatures from ca. 10 mK to a few tens of kelvins. The operation of CBT is based on single electron charging effects in normal metal tunnel junctions. In this paper, we discuss the typical error sources and uncertainty components that limit the present absolute accuracy of the CBT measurements to the level of about 1 % in the optimum temperature range. Identifying the influence of different uncertainty sources is a good starting point for improving the measurement accuracy to the level that would allow the CBT to be more widely used in high-precision low temperature metrological applications and for realizing thermodynamic temperature in accordance to the upcoming new definition of kelvin.

  11. Coulomb collisions and coronal heating by velocity filtration

    NASA Astrophysics Data System (ADS)

    Anderson, Stephen W.

    1994-12-01

    We introduce the effects of Coulomb collisions to the velocity filtration model of coronal heating, which has so far been done collisionlessly. Non-Maxwellian particle distributions are at the heart of this model, so collisions, which force such distributions to relax, can play a critical role. We consider a column of plasma extending upwards from the bottom of the corona and use typical transition zone densities and temperatures as well as the non-Maxwellian kappa distribution previously used in this model. We demonstrate the collisions are an important factor by comparing electron density and energy profiles predicted by the collisionless Vlasov equation to ones made using the assumption that collisions are a small, first-order perturbation. For the heights considered (below 0.5 solar radius), these collisional corrections are of order unity or larger. We conclude that the velocity filtration model needs to be redone including collisions self-consistently.

  12. Coulomb-stable triply charged diatomic: HeY3+

    NASA Astrophysics Data System (ADS)

    Wesendrup, Ralf; Pernpointner, Markus; Schwerdtfeger, Peter

    1999-11-01

    Accurate relativistic coupled-cluster calculations show that the triply charged species HeY3+ is a stable molecule and represents the lightest diatomic trication that does not undergo a Coulomb fragmentation into charged fragments. The diatomic potential-energy curve is approximated by an extended Morse potential, and vibrational-rotational constants for HeY3+ are predicted (Re=224.3 pm, D0=0.394 eV, ωe=437 cm-1, ωexe=15.8 cm-1, Be=0.877 cm-1). It is further shown that the He-Y3+ bond can basically be described as a charge-induced dipole interaction.

  13. Ultra-high-ohmic microstripline resistors for Coulomb blockade devices.

    PubMed

    Lotkhov, Sergey V

    2013-06-14

    In this paper, we report on the fabrication and low-temperature characterization of ultra-high-ohmic microstripline resistors made of a thin film of weakly oxidized titanium. Nearly linear voltage-current characteristics were measured at temperatures down to T ~ 20 mK for films with sheet resistivities as high as ~7 kΩ, i.e. about an order of magnitude higher than our previous findings for weakly oxidized Cr. Our analysis indicates that such an improvement can help to create an advantageous high-impedance environment for different Coulomb blockade devices. Further properties of the Ti film addressed in this work show the promise of low-noise behavior of the resistors when applied in different realizations of the quantum standard of current. PMID:23670293

  14. Gravitational Modification of the Coulomb-Breit Hamiltonian

    SciTech Connect

    Caicedo, Jose Alexander; Urrutia, Luis Fernando

    2009-04-20

    In the poster session we presented a short review of our first results in the construction of the Coulomb-Breit Hamiltonian for a pair of fermions immersed in a background gravitational field which is described by General Relativity. Here we present a resume of that construction. We make a special stress on the objectives and the hypothesis used, but there is no special attention on the explicit form of the results because actually there is an updated and optimised version of our work in the edition process for publication; however we mention some special characteristics of the effect of the background gravitational field on the quantum nature of the system composed by fermions and its electromagnetic field, particularly the possibility of the observation of centre of mass effects in matter interferometry experiments.

  15. Highly accurate eigenvalues for the distorted Coulomb potential

    NASA Astrophysics Data System (ADS)

    Ixaru, L. Gr.; de Meyer, H.; vanden Berghe, G.

    2000-03-01

    We consider the eigenvalue problem for the radial Schrödinger equation with potentials of the form V(r)=S(r)/r+R(r) where S(r) and R(r) are well behaved functions which tend to some (not necessarily equal) constants when r-->0 and r-->∞. Formulas (14.4.5)-(14.4.8) of Abramowitz and Stegun [Handbook of Mathematical Functions, 8th ed. (Dover, New York, 1972)], corresponding to the pure Coulomb case, are here generalized for this distorted case. We also present a complete procedure for the numerical solution of the problem. Our procedure is robust, very economic and particularly suited for very large n. Numerical illustrations for n up to 2000 are given.

  16. 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.

  17. 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.

  18. Bounded solutions of neutral fermions with a screened Coulomb potential

    SciTech Connect

    Castro, Antonio S. de . E-mail: castro@feg.unesp.br

    2005-11-01

    The intrinsically relativistic problem of a fermion subject to a pseudoscalar screened Coulomb plus a uniform background potential in two-dimensional space-time is mapped into a Sturm-Liouville. This mapping gives rise to an effective Morse-like potential and exact bounded solutions are found. It is shown that the uniform background potential determinates the number of bound-state solutions. The behaviour of the eigenenergies as well as of the upper and lower components of the Dirac spinor corresponding to bounded solutions is discussed in detail and some unusual results are revealed. An apparent paradox concerning the uncertainty principle is solved by recurring to the concepts of effective mass and effective Compton wavelength.

  19. Communication: Phase space wavelets for solving Coulomb problems.

    PubMed

    Shimshovitz, Asaf; Tannor, David J

    2012-09-14

    Recently we introduced a phase space approach for solving the time-independent Schrödinger equation using a periodic von Neumann basis with bi-orthogonal exchange (pvb) [A. Shimshovitz and D. J. Tannor, Phys. Rev. Lett. 109, 070402 (2012)]. Here we extend the approach to allow a wavelet scaling of the phase space Gaussians. The new basis set, which we call the wavelet pvb basis, is simple to implement and provides an appealing alternative to other wavelet approaches. For the 1D Coulomb problems tested in this paper, the method reduces the size of the basis relative to the Fourier grid method by a factor of 13-60. The savings in basis set size is predicted to grow steeply as the dimensionality increases. PMID:22979843

  20. 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.

  1. Coulomb gauge confinement in the heavy quark limit

    SciTech Connect

    Popovici, C.; Watson, P.; Reinhardt, H.

    2010-05-15

    The relationship between the nonperturbative Green's functions of Yang-Mills theory and the confinement potential is investigated. By rewriting the generating functional of quantum chromodynamics in terms of a heavy quark mass expansion in Coulomb gauge, restricting to leading order in this expansion and considering only the two-point functions of the Yang-Mills sector, the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is shown to be exact in this case and an analytic, nonperturbative solution is presented. It is found that there is a direct connection between the string tension and the temporal gluon propagator. Further, it is shown that for the 4-point quark correlation functions, only confined bound states of color-singlet quark-antiquark (meson) and quark-quark (baryon) pairs exist.

  2. Strong nuclear couplings as a source of Coulomb rainbow suppression

    SciTech Connect

    Keeley, N.; Alamanos, N.; Rusek, K.

    2010-09-15

    A recent measurement of the {sup 11}Be+{sup 64}Zn quasielastic scattering angular distribution exhibits a non-Fresnel-type pattern, in contrast to {sup 6}He+{sup 64}Zn elastic scattering but similar to that for the elastic scattering of {sup 6}He from heavy targets. We show by means of continuum discretized coupled-channels (CDCC) calculations that this unusual behavior of {sup 11}Be is caused by the much greater importance of nuclear coupling to the continuum in {sup 11}Be compared to {sup 6}He, where Coulomb dipole coupling is mainly responsible for the non-Fresnel-like shape, when present. We also show that the dynamic polarization potentials derived from the CDCC calculations seem to follow a universal form as a function of radius.

  3. Dynamic stresses, coulomb failure, and remote triggering: corrected

    USGS Publications Warehouse

    Hill, David P.

    2012-01-01

    Dynamic stresses associated with crustal surface waves with 15–30 s periods and peak amplitudes <1  MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid‐onset triggered seismicity that develop during the surface‐wave peak dynamic stressing. Evaluation of the triggering potential of surface‐wave dynamic stresses acting on critically stressed faults using a Mohr’s circle representation together with the Coulomb failure criteria indicates that Love waves should have a higher triggering potential than Rayleigh waves for most fault orientations and wave incidence angles. That (1) the onset of triggered seismicity often appears to begin during the Rayleigh wave rather than the earlier arriving Love wave, and (2) Love‐wave amplitudes typically exceed those for Rayleigh waves suggests that the explanation for rapid‐onset dynamic triggering may not reside solely with a simple static‐threshold friction mode. The results also indicate that normal faults should be more susceptible to dynamic triggering by 20‐s Rayleigh‐wave stresses than thrust faults in the shallow seismogenic crust (<10  km) while the advantage tips in favor of reverse faults greater depths. This transition depth scales with wavelength and coincides roughly with the transition from retrograde‐to‐prograde particle motion. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems. The result is consistent with the apparent elevated susceptibility of extensional or transtensional tectonic regimes to remote triggering by Rayleigh‐wave dynamic stresses than compressional or transpressional regimes.

  4. 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.

  5. 8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

  6. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    SciTech Connect

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-14

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  7. Coulomb collisions in the Boltzmann equation for electrons in low-temperature gas discharge plasmas

    NASA Astrophysics Data System (ADS)

    Hagelaar, G. J. M.

    2016-02-01

    This paper investigates the effects of electron-electron and electron-ion Coulomb collisions on the electron distribution function and transport coefficients obtained from the Boltzmann equation for simple dc gas discharge conditions. Expressions are provided for the full Coulomb collision terms acting on both the isotropic and anisotropic parts of the electron distribution function, which are then incorporated in the freeware Boltzmann equation solver BOLSIG+. Different Coulomb collision effects are demonstrated and discussed on the basis of BOLSIG+  results for argon gas. It is shown that the anisotropic part of the electron-electron collision term, neglected in previous work, can in certain cases have a large effect on the electron mobility and is essential when describing the transition towards the Coulomb-collision dominated regime characterized by Spitzer transport coefficients. Finally, a brief overview is presented of the discharge conditions for which different Coulomb collision effects occur in different gases.

  8. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-01

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  9. Magnetic monopole and string excitations in two-dimensional spin ice

    NASA Astrophysics Data System (ADS)

    Mól, L. A.; Silva, R. L.; Silva, R. C.; Pereira, A. R.; Moura-Melo, W. A.; Costa, B. V.

    2009-09-01

    We study the magnetic excitations of a square lattice spin ice recently produced in an artificial form as an array of nanoscale magnets. Our analysis, based on the dipolar interaction between the nanomagnetic islands, correctly reproduces the ground state observed experimentally. In addition, we find magnetic monopolelike excitations effectively interacting by means of the usual Coulombic plus a linear confining potential, the latter being related to a stringlike excitation binding the monopoles pairs, which indicates that the fractionalization of magnetic dipoles may not be so easy in two dimensions. These findings contrast this material with the three-dimensional analog, where such monopoles experience only the Coulombic interaction. We discuss, however, two entropic effects that affect the monopole interactions. First, the string configurational entropy may lose the string tension and then free magnetic monopoles should also be found in lower dimensional spin ices; second, in contrast to the string configurational entropy, an entropically driven Coulomb force, which increases with temperature, has the opposite effect of confining the magnetic defects.

  10. Laser Isotope Separation Employing Condensation Repression

    SciTech Connect

    Eerkens, Jeff W.; Miller, William H.

    2004-09-15

    Molecular laser isotope separation (MLIS) techniques using condensation repression (CR) harvesting are reviewed and compared with atomic vapor laser isotope separation (AVLIS), gaseous diffusion (DIF), ultracentrifuges (UCF), and electromagnetic separations (EMS). Two different CR-MLIS or CRISLA (Condensation Repression Isotope Separation by Laser Activation) approaches have been under investigation at the University of Missouri (MU), one involving supersonic super-cooled free jets and dimer formation, and the other subsonic cold-wall condensation. Both employ mixtures of an isotopomer (e.g. {sup i}QF{sub 6}) and a carrier gas, operated at low temperatures and pressures. Present theories of VT relaxation, dimerization, and condensation are found to be unsatisfactory to explain/predict experimental CRISLA results. They were replaced by fundamentally new models that allow ab-initio calculation of isotope enrichments and predictions of condensation parameters for laser-excited and non-excited vapors which are in good agreement with experiment. Because of supersonic speeds, throughputs for free-jet CRISLA are a thousand times higher than cold-wall CRISLA schemes, and thus preferred for large-quantity Uranium enrichments. For small-quantity separations of (radioactive) medical isotopes, the simpler coldwall CRISLA method may be adequate.

  11. Excited Charm States

    SciTech Connect

    Shukla, S.

    1994-12-31

    Characteristics of mass spectra and decays of orbitally excited charm mesons and baryons, expected on the basis of quark models and Heavy Quark Symmetry, are briefly described. The difficulties associated with measurements on these excited states are discussed. The accuracy and reliability of currently available experimental information is examined. The reasons, for the widely accepted spin-parity assignments to the observed excited mesons and baryons, are stated. Finally, the experimental data, with the accepted spin-parity assignments, is compared with expectations based on quark models and Heavy Quark Symmetry.

  12. Probing core-electron orbitals by scanning transmission electron microscopy and measuring the delocalization of core-level excitations

    NASA Astrophysics Data System (ADS)

    Jeong, Jong Seok; Odlyzko, Michael L.; Xu, Peng; Jalan, Bharat; Mkhoyan, K. Andre

    2016-04-01

    By recording low-noise energy-dispersive x-ray spectroscopy maps from crystalline specimens using aberration-corrected scanning transmission electron microscopy, it is possible to probe core-level electron orbitals in real space. Both the 1 s and 2 p orbitals of Sr and Ti atoms in SrTi O3 are probed, and their projected excitation potentials are determined. This paper also demonstrates experimental measurement of the electronic excitation impact parameter and the delocalization of an excitation due to Coulombic beam-orbital interaction.

  13. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  14. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  15. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  16. Method for separating isotopes

    DOEpatents

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  17. Stable isotope studies

    SciTech Connect

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  18. Calculation of total electron excitation cross-sections and partial electron ionization cross-sections for the elements. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Green, T. J.

    1973-01-01

    Computer programs were used to calculate the total electron excitation cross-section for atoms and the partial ionization cross-section. The approximations to the scattering amplitude used are as follows: (1) Born, Bethe, and Modified Bethe for non-exchange excitation; (2) Ochkur for exchange excitation; and (3) Coulomb-Born of non-exchange ionization. The amplitudes are related to the differential cross-sections which are integrated to give the total excitation (or partial ionization) cross-section for the collision. The atomic wave functions used are Hartree-Fock-Slater functions for bound states and the coulomb wave function for the continuum. The programs are presented and the results are examined.

  19. Excitation by rockets

    NASA Technical Reports Server (NTRS)

    Tammadge, C. E.

    1975-01-01

    Standard methods of excitation are not always practical when a single mode of known frequency requires investigation. This form of investigation is often required on a modified aircraft. A new method of excitation was developed and proved in flight, which consists of firing small rocket charges attached to the aircraft structure. Damping values at gradually increasing airspeeds are obtained, as in Stick Jerk tests, and flutter speeds predicted.

  20. Excitation functions for actinides produced in the interactions of sup 31 P with sup 248 Cm

    SciTech Connect

    Leyba, J.D.; Henderson, R.A.; Hall, H.L.; Czerwinski, K.R.; Kadkhodayan, B.A.; Kreek, S.A.; Brady, E.K.; Gregorich, K.E.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. Nuclear Science Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California )

    1991-11-01

    Excitation functions have been measured for the production of various isotopes of Bk, Cf, Es, and Fm from the interactions of 174- and 239-MeV {sup 31}P projectiles with {sup 248}Cm. The isotopic distributions were symmetric and displayed full widths at half maximum of 2.5, 2.5, and 2.25 mass units for Bk, Cf, and Fm, respectively. The maxima of the isotopic distributions occur for those reaction channels which involve the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy is a positive quantity. The maxima of the excitation functions occur at those projectile energies which are consistent with the calculated reaction barriers based upon a binary reaction mechanism. The effects of the odd proton in the {sup 31}P projectile on the final isotopic distributions are discussed.

  1. The effect of the partner atom on the spectra of interatomic Coulombic decay triggered by resonant Auger processes

    SciTech Connect

    Miteva, T. Chiang, Y.-C.; Kuleff, A. I.; Cederbaum, L. S.; Gokhberg, K.; Kolorenč, P.

    2014-10-28

    The resonant-Auger – interatomic Coulombic decay (ICD) cascade was recently suggested as an efficient means of controlling the course of the ICD process. Recent theoretical and experimental works show that control over the energies of the emitted ICD electrons can be achieved either by varying the photon energy to produce different initial core excitations or by changing the neighboring species. This work presents a theoretical investigation on the role of the rare-gas neighbor and clarifies how the latter influences the ICD process. For this purpose, we compare fully ab initio computed ICD-electron and kinetic energy release spectra following the 2p{sub 3/2} → 4s, 2p{sub 1/2} → 4s and 2p{sub 3/2} → 3d of Ar in ArKr and Ar{sub 2}. We demonstrate that the presence of the chemically “softer” partner atom results in an increase in the energies of the emitted ICD electrons, and also in the appearance of additional ICD-active states. The latter leads to a threefold increase in the ICD yield for the case of the 2p{sub 3/2,} {sub 1/2} → 4s parent core excitations.

  2. Poisson Green's function method for increased computational efficiency in numerical calculations of Coulomb coupling elements

    NASA Astrophysics Data System (ADS)

    Zimmermann, Anke; Kuhn, Sandra; Richter, Marten

    2016-01-01

    Often, the calculation of Coulomb coupling elements for quantum dynamical treatments, e.g., in cluster or correlation expansion schemes, requires the evaluation of a six dimensional spatial integral. Therefore, it represents a significant limiting factor in quantum mechanical calculations. If the size or the complexity of the investigated system increases, many coupling elements need to be determined. The resulting computational constraints require an efficient method for a fast numerical calculation of the Coulomb coupling. We present a computational method to reduce the numerical complexity by decreasing the number of spatial integrals for arbitrary geometries. We use a Green's function formulation of the Coulomb coupling and introduce a generalized scalar potential as solution of a generalized Poisson equation with a generalized charge density as the inhomogeneity. That enables a fast calculation of Coulomb coupling elements and, additionally, a straightforward inclusion of boundary conditions and arbitrarily spatially dependent dielectrics through the Coulomb Green's function. Particularly, if many coupling elements are included, the presented method, which is not restricted to specific symmetries of the model, presents a promising approach for increasing the efficiency of numerical calculations of the Coulomb interaction. To demonstrate the wide range of applications, we calculate internanostructure couplings, such as the Förster coupling, and illustrate the inclusion of symmetry considerations in the method for the Coulomb coupling between bound quantum dot states and unbound continuum states.

  3. Excitation rate and background measurements during LIF studies on krypton

    NASA Astrophysics Data System (ADS)

    Whitehead, C. A.; Cannon, B. D.; Wacker, J. F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure Kr-85 concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce Kr-85 to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p(sub 6) state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the Kr-85 isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p(sub 8) energy level. Non-isotopically selective de-excitation rates as high as 5 x 10(exp 5)/sec have been measured, yielding a signal-to-background ratio of g reater than 10(exp 6). The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by Kr-85. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2-3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  4. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure {sup 85}Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce {sup 85}Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p{sub 6} state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the {sup 85}Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p{sub 8} energy level. Non-isotopically selective de-excitation rates as high as 5 {times} 10{sup 5} sec{sup {minus}1} have been measured, yielding a signal-to-background ratio of >10{sup 6}. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by {sup 85}Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  5. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure [sup 85]Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce [sup 85]Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p[sub 6] state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the [sup 85]Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p[sub 8] energy level. Non-isotopically selective de-excitation rates as high as 5 [times] 10[sup 5] sec[sup [minus]1] have been measured, yielding a signal-to-background ratio of >10[sup 6]. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by [sup 85]Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  6. Coulomb drag between one-dimensional electron systems

    NASA Astrophysics Data System (ADS)

    Muhammad, Mustafa

    We have measured Coulomb drag (CD) between two spatially separated and electrically isolated one-dimensional (1D) wires to study the Luttinger liquid (LL) state in 1D systems. We have fabricated dual-wire CD devices with long quantum wires (≥ 1 microm) and short quantum wires (≤ 500 nm) with respect to the thermal lengths. The devices are made from high-mobility (≅10 6cm2/Vs) two-dimensional electron gas (2DEG) in AlGaAs/GaAs heterostructures, using high-resolution e-beam lithography, combined with metal deposition by e-beam evaporation to form surface Schottky gates. Peak in drag voltage occurs when the subband bottoms of the lowest energy subbands of the drive and the drag wires line up with each other and the Fermi level. We have observed drag on 1 microm device at 22 mK temperature which is found to be reminiscent of the drag observed earlier on a 2 microm device. An extensive reanalysis of the drag results obtained on the 2 microm device indicates a power-law temperature dependence of drag for both identical and non-identical wires. Also drag is found to decay exponentially with the mismatch between the wires. These properties indicate the existence of Luttinger liquid (LL) state in the long wire device. We have observed positive and negative drags on short wire devices. The observed temperature dependence of drag resistance, for both positive and negative drags, shows first an increase, followed by a constant plateau and finally a decrease as the temperature is increased. This is in line with the predictions of the Fermi--Luttinger liquid (FLL) forward momentum transfer theory. This is the first experimental observation of 1D Coulomb drag due to forward momentum transfer between wires. A negative drag between same type of carriers (holes or electrons) may conceivably result from forward momentum transfer or forward scattering if the band curvature of the drag wire at or near the Fermi point is negative. Negative band curvature may result from asymmetry

  7. Coulomb drag between one-dimensional electron systems

    NASA Astrophysics Data System (ADS)

    Muhammad, Mustafa

    We have measured Coulomb drag (CD) between two spatially separated and electrically isolated one-dimensional (1D) wires to study the Luttinger liquid (LL) state in 1D systems. We have fabricated dual-wire CD devices with long quantum wires (≥ 1 mum) and short quantum wires (≤ 500 nm) with respect to the thermal lengths. The devices are made from high-mobility (≅106cm2/Vs) two-dimensional electron gas (2DEG) in AlGaAs/GaAs heterostructures, using high-resolution e-beam lithography, combined with metal deposition by e-beam evaporation to form surface Schottky gates. Peak in drag voltage occurs when the subband bottoms of the lowest energy subbands of the drive and the drag wires line up with each other and the Fermi level. We have observed drag on 1 mum device at 22 mK temperature which is found to be reminiscent of the drag observed earlier on a 2 mum device. An extensive reanalysis of the drag results obtained on the 2 mum device indicates a power-law temperature dependence of drag for both identical and non-identical wires. Also drag is found to decay exponentially with the mismatch between the wires. These properties indicate the existence of Luttinger liquid (LL) state in the long wire device. We have observed positive and negative drags on short wire devices. The observed temperature dependence of drag resistance, for both positive and negative drags, shows first an increase, followed by a constant plateau and finally a decrease as the temperature is increased. This is in line with the predictions of the Fermi-Luttinger liquid (FLL) forward momentum transfer theory. This is the first experimental observation of 1D Coulomb drag due to forward momentum transfer between wires. A negative drag between same type of carriers (holes or electrons) may conceivably result from forward momentum transfer or forward scattering if the band curvature of the drag wire at or near the Fermi point is negative. Negative band curvature may result from asymmetry in the wire

  8. Electronic ground state properties of Coulomb blockaded quantum dots

    NASA Astrophysics Data System (ADS)

    Patel, Satyadev Rajesh

    Conductance through quantum dots at low temperature exhibits random but repeatable fluctuations arising from quantum interference of electrons. The observed fluctuations follow universal statistics arising from the underlying universality of quantum chaos. Random matrix theory (RMT) has provided an accurate description of the observed universal conductance fluctuations (UCF) in "open" quantum dots (device conductance ≥e 2/h). The focus of this thesis is to search for and decipher the underlying origin of similar universal properties in "closed" quantum dots (device conductance ≤e2/ h). A series of experiments is presented on electronic ground state properties measured via conductance measurements in Coulomb blockaded quantum dots. The statistics of Coulomb blockade (CB) peak heights with zero and non-zero magnetic field measured in various devices agree qualitatively with predictions from Random Matrix Theory (RMT). The standard deviation of the peak height fluctuations for non-zero magnetic field is lower than predicted by RMT; the temperature dependence of the standard deviation of the peak height for non-zero magnetic field is also measured. The second experiment summarizes the statistics of CB peak spacings. The peak spacing distribution width is observed to be on the order of the single particle level spacing, Delta, for both zero and non-zero magnetic field. The ratio of the zero field peak spacing distribution width to the non-zero field peak spacing distribution width is ˜1.2; this is good agreement with predictions from spin-resolved RMT predictions. The standard deviation of the non-zero magnetic field peak spacing distribution width shows a T-1/2 dependence in agreement with a thermal averaging model. The final experiment summarizes the measurement of the peak height correlation length versus temperature for various quantum dots. The peak height correlation length versus temperature saturates in small quantum dots, suggesting spectral scrambling

  9. Lifetime measurement of excited low-spin states via the (p, p‧ γ) reaction

    NASA Astrophysics Data System (ADS)

    Hennig, A.; Derya, V.; Mineva, M. N.; Petkov, P.; Pickstone, S. G.; Spieker, M.; Zilges, A.

    2015-09-01

    In this paper a method for lifetime measurements in the sub-picosecond regime via the Doppler-shift attenuation method (DSAM) following the inelastic proton scattering reaction is presented. In a pioneering experiment we extracted the lifetimes of 30 excited low-spin states of 96Ru, taking advantage of the coincident detection of scattered protons and de-exciting γ-rays as well as the large number of particle and γ-ray detectors provided by the SONIC@HORUS setup at the University of Cologne. The large amount of new experimental data shows that this technique is suited for the measurement of lifetimes of excited low-spin states, especially for isotopes with a low isotopic abundance, where (n ,n‧ γ) or - in case of investigating dipole excitations - (γ ,γ‧) experiments are not feasible due to the lack of sufficient isotopically enriched target material.

  10. Infrared analysis of propagators and vertices of Yang-Mills theory in Landau and Coulomb gauge

    SciTech Connect

    Schleifenbaum, W.; Leder, M.; Reinhardt, H.

    2006-06-15

    The infrared behavior of gluon and ghost propagators, ghost-gluon vertex, and three-gluon vertex is investigated for both the covariant Landau and the noncovariant Coulomb gauge. Assuming infrared ghost dominance, we find a unique infrared exponent in the d=4 Landau gauge, while in the d=3+1 Coulomb gauge we find two different infrared exponents. We also show that a finite dressing of the ghost-gluon vertex has no influence on the infrared exponents. Finally, we determine the infrared behavior of the three-gluon vertex analytically and calculate it numerically at the symmetric point in the Coulomb gauge.

  11. Coulomb corrections to the parameters of the Landau-Pomeranchuk-Migdal effect theory

    NASA Astrophysics Data System (ADS)

    Voskresenskaya, O.; Kuraev, E.; Torosyan, H.

    2014-07-01

    Using the Coulomb correction to the screening angular parameter of the Molière multiple scattering theory we obtained analytically and numerically the Coulomb corrections to the quantities of the Migdal LPM effect theory. We showed that the Coulomb correction to the spectral bremsstrahlung rate allows one to eliminate the discrepancy between the predictions of the LPM effect theory and its measurement at least for high- Z targets and also to improve additionally the agreement between the predictions of the LPM effect theory analogue for a thin layer of matter and experimental data.

  12. 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

  13. 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.

  14. 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.

  15. Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Young, J. P.; Shaw, R. W.

    1995-08-01

    A diode-laser step has been incorporated into a resonance-ionization mass spectrometry optical excitation process to enhance the isotopic selectivity of the technique. Lanthanum isotope ratio enhancements as high as 103 were achieved by use of a single-frequency cw diode laser tuned to excite the first step of a three-step excitation-ionization optical process; the subsequent steps were excited by use of a pulsed dye laser. Applying the same optical technique, we measured atomic hyperfine constants for the high-lying even-parity 4D5/2 state of lanthanum at 30354 cm-1 . The general utility of this spectral approach is discussed.

  16. Dark Coulomb binding of heavy neutrinos of fourth family

    NASA Astrophysics Data System (ADS)

    Belotsky, K. M.; Esipova, E. A.; Khlopov, M. Yu.; Laletin, M. N.

    2015-11-01

    Direct dark matter searches put severe constraints on the weakly interacting massive particles (WIMPs). These constraints cause serious troubles for the model of stable neutrino of fourth generation with mass around 50GeV. Though the calculations of primordial abundance of these particles make them in the charge symmetric case a sparse subdominant component of the modern dark matter, their presence in the universe would exceed the current upper limits by several orders of the magnitude. However, if quarks and leptons of fourth generation possess their own Coulomb-like y-interaction, recombination of pairs of heavy neutrinos and antineutrinos and their annihilation in the “neutrinium” atoms can play important role in their cosmological evolution, reducing their modern abundance far below the experimental upper limits. The model of stable fourth generation assumes that the dominant part of dark matter is explained by excessive Ū antiquarks, forming (ŪŪŪ)-- charged clusters, bound with primordial helium in nuclear-interacting O-helium (OHe) dark atoms. The y charge conservation implies generation of the same excess of fourth generation neutrinos, potentially dangerous WIMP component of this scenario. We show that due to y-interaction recombination of fourth neutrinos with OHe hides these WIMPs from direct WIMP searches, leaving the negligible fraction of free neutrinos, what makes their existence compatible with the experimental constraints.

  17. The mystery of Coulomb friction in sediment transport

    NASA Astrophysics Data System (ADS)

    Pähtz, Thomas; Duran, Orencio

    Nearly all analytical models of sediment transport in Newtonian fluid (e.g., air or water) are based on Bagnold's assumption of a constant Coulomb friction coefficient (particle-shear-pressure-ratio, μ) at the interface (zb) between sediment bed and transport layer. In fact, this assumption is the main reason why these models predict the sediment load (and subsequently the sediment transport rate) to be proportional to the excess shear stress (τ -τt), a scaling which has been confirmed in many wind-tunnel and flume experiments. Attempts to explain why μ (zb) is constant have usually been based on the sliding-friction analogy or rheology arguments. However, here we analytically derive μ (zs) √{ 3} - 1 , where zs is the location at which the production rate of particle fluctuation energy is maximal. Our derivation is based on the assumption that the rate of collisional transfer of horizontal into vertical kinetic energy is typically much larger than the rate of energy dissipation. Using state-of-the-art numerical simulations of sediment transport in Newtonian fluid, we validate all assumptions and approximation involved in our derivation. Interestingly, the location zs can significantly deviate from zb depending on the simulated conditions. We acknowledge support from grants National Natural Science Foundation of China (Nos. 1151101041 and 41376095) and Natural Science Foundation of Zhejiang Province (No. LR16E090001).

  18. Enhanced current noise correlations in a Coulomb-Majorana device

    NASA Astrophysics Data System (ADS)

    Lü, Hai-Feng; Lu, Hai-Zhou; Shen, Shun-Qing

    2016-06-01

    Majorana bound states (MBSs) nested in a topological nanowire are predicted to manifest nonlocal correlations in the presence of a finite energy splitting between the MBSs. However, the signal of the nonlocal correlations has not yet been detected in experiments. A possible reason is that the energy splitting is too weak and seriously affected by many system parameters. Here we investigate the charging energy induced nonlocal correlations in a hybrid device of MBSs and quantum dots. The nanowire that hosts the MBSs is assumed in proximity to a mesoscopic superconducting island with a finite charging energy. Each end of the nanowire is coupled to one lead via a quantum dot with resonant levels. With a floating superconducting island, the devices show a negative differential conductance and giant super-Poissonian shot noise, due to the interplay between the nonlocality of the MBSs and dynamical Coulomb blockade effect. When the island is strongly coupled to a bulk superconductor, the current cross correlations at small lead chemical potentials are negative by tuning the dot energy levels. In contrast, the cross correlation is always positive in a non-Majorana setup. This difference may provide a signature for the existence of the MBSs.

  19. Coulomb blockade phenomena in ultrathin Langmuir-Blodgett sandwich junctions

    NASA Astrophysics Data System (ADS)

    Burghard, M.; Mueller-Schwanneke, C.; Philipp, G.; Roth, S.

    1999-04-01

    Electrical junctions were fabricated in sandwich configuration from Langmuir-Blodgett (LB) films of two types of material, 0953-8984/11/14/015/img1-conjugated, peripherally substituted ring systems or a 0953-8984/11/14/015/img2-bonded polymer. The sandwich junctions consisted of four to ten monolayers between two micro-structured gold electrodes, corresponding to a nominal film thickness between about 8 and 20 nm. At liquid helium temperature, the current (I)/voltage (V) characteristics generally exhibited smooth exponential behaviour or irregular steps. However, for a small fraction of the LB sandwiches comprising a 0953-8984/11/14/015/img1-conjugated or 0953-8984/11/14/015/img2-bonded compound, regular staircases were observed. It was possible to fit such 0953-8984/11/14/015/img5 characteristics with curves calculated on the basis of a Coulomb blockade model. These results are accounted for by the presence of nanometre-sized gold particles formed upon evaporation of the top electrode. Single electron tunnelling is assumed to proceed through double tunnel barrier junctions consisting of a gold island asymmetrically located between the top and bottom electrode.

  20. Le probleme quantique bicomplexe du potentiel de Coulomb

    NASA Astrophysics Data System (ADS)

    Mathieu, Jeremie

    In this master's thesis, is gathered a great part of my work on bicomplex quantum mechanics. Bicomplex numbers are the second order multicomplex generalization of complex numbers. Equipped with the standard addition and multiplication, they form an algebraic structure called a commutative ring with unity and are one of many known generalizations of the real number system. It has been almost eighty years since it's been proposed to use an algebra of a superior dimension than the one of complex numbers to construct the mathematical formalism of quantum mechanics. However it's only been since less than a decade ago that the idea of using the bicomplex numbers to do so has been seriously considered. In that sense, the complete resolution of the quantum harmonic oscillator in a bicomplex Hilbert space was the first major achievement of this ambitious project. This thesis, by article style, is a continuation of this work of generalization. It presents, by an axiomatic approach, the complete differential solution of the bicomplex quantum Coulomb potential problem and half of its algebraic solution.