Measurement of the 92,93,94,100Mo(g,n) reactions by Coulomb Dissociation
Göbel, K; 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; Pramanik, U Datta; Deveaux, L; Elvers, M; Elze, T W; Emling, H; Erhard, M; Ershova, O; 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; Bleis, T Le; 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
2013-01-01
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 f\\"ur 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(g,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94Mo(g,n) reaction is presented. Further analysis will complete the experimental database for the (g,n) production chain of the p-isotopes of molybdenum.
Measurement of fusion excitation functions in the system {sup 78}Kr + {sup 100}Mo
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
Earlier measurements of fusion reactions involving {sup 78}Kr and {sup 100}Mo projectiles and Ni-targets showed surprisingly large fusion yields at low energies which could not be explained by coupled-channels calculations. The main difference to similar measurements involving the neighboring {sup 86}Kr and {sup 92}Mo isotopes was the different slope of the excitation functions at sub-barrier energies. An analysis of a variety of experiments showed a correlation between the nuclear structure and the slope of the excitation functions, with the {open_quotes}soft{close_quotes} transitional nuclei ({sup 78}Kr, {sup 100}Mo) exhibiting shallower slopes than the {open_quotes}stiff{close_quotes} nuclei ({sup 86}Kr, {sup 92}Mo) measured at the same energies with respect to the barrier. In this experiment we studied the fusion excitation function involving two transitional nuclei {sup 78}Kr + {sup 100}Mo. The measurements were performed with {sup 78}Kr beams from the ECR source at energies between 285-370 MeV. Separation of the evaporation nucleus from the elastically scattered particles was achieved by measuring time-of-flight and magnetic rigidity in the gas-filled spectrograph. The data were completely analyzed. A comparison of the cross sections with measurements for the system {sup 86}Kr + {sup 92}Mo populating the same compound nucleus {sup 178}Pt. It shows good agreement at the highest energies, but quite different falloffs of the excitation functions toward lower energies. Coupled-channels calculations, including multi-phonon excitation for the two systems, are being performed.
Measurement of double beta decay of 100Mo to excited states in the NEMO 3 experiment
The double beta decay of 100Mo to the 01+ and 21+ excited states of 100Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of 100Mo to the excited 01+ state is measured to be T1/2(2ν)=[5.7-0.9+1.3(stat.)+/-0.8(syst.)]x1020 y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 01+ state has been found. The corresponding half-life limit is T1/2(0ν)(0+->01+)>8.9x1022 y (at 90% C.L.). The search for the double beta decay to the 21+ excited state has allowed the determination of limits on the half-life for the two neutrino mode T1/2(2ν)(0+->21+)>1.1x1021 y (at 90% C.L.) and for the neutrinoless mode T1/2(0ν)(0+->21+)>1.6x1023 y (at 90% C.L.)
Measurement of double beta decay of 100Mo to excited states in the NEMO 3 experiment
Arnold, R; Baker, J; Barabash, A S; Bongrand, M; Broudin, G; Brudanin, V; Caffrey, A J; Egorov, V; Etienvre, A I; Fatemi-Ghomi, N; Hubert, F; Hubert, P; Jerie, J; Jollet, C; Jullian, S; King, S; Kochetov, O; Konovalov, S I; Kovalenko, V; Lalanne, D; Lamhamdi, T; Leccia, F; Lemière, Y; Longuemare, C; Lutter, G; Marquet, C; Mauger, F; Nachab, A; Ohsumi, H; Perrot, F; Piquemal, F; Reyss, J L; Ricol, J S; Saakyan, R; Sarazin, X; Shitov, Y; Simard, L; Simkovic, F; Smolnikov, A; Stekl, I; Suhonen, J; Sutton, C S; Szklarz, G; Söldner-Rembold, S; Thomas, J; Timkin, V; Tretyak, V; Umatov, V; Vanyushin, I A; Vasilev, V; Vorobel, V; Vylov, T; Vàla, L; Hubert, Ph.; Marquet, Ch.; Shitov, Yu.; Vylov, Ts.
2007-01-01
The double beta decay of 100Mo to the 0^+_1 and 2^+_1 excited states of 100Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of 100Mo to the excited 0^+_1 state is measured to be T^(2nu)_1/2 = [5.7^{+1.3}_{-0.9}(stat)+/-0.8(syst)]x 10^20 y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 0^+_1 state has been found. The corresponding half-life limit is T^(0nu)_1/2(0^+ --> 0^+_1) > 8.9 x 10^22 y (at 90% C.L.). The search for the double beta decay to the 2^+_1 excited state has allowed the determination of limits on the half-life for the two neutrino mode T^(2nu)_1/2(0^+ --> 2^+_1) > 1.1 x 10^21 y (at 90% C.L.) and for the neutrinoless mode T^(0nu)_1/2(0^+ --> 2^+_1) > 1.6 x 10^23 y (at 90% C.L.).
Coulomb excitations of monolayer germanene
Shih, Po-Hsin; Wu, Jhao-Ying; Shyu, Feng-Lin; Lin, Ming-Fa
2016-01-01
The feature-rich electronic excitations of monolayer germanene lie in the significant spin-orbital coupling and the buckled structure. The collective and single- particle excitations are diversified by the magnitude and direction of transferred momentum, the Fermi energy and the gate voltage. There are four kinds of plasmon modes, according to the unique frequency- and momentum-dependent phase diagrams. They behave as two-dimensional acoustic modes at long wavelength. However, for the larger momenta, they might change into another kind of undamped plasmons, become the seriously suppressed modes in the heavy intraband e-h excitations, keep the same undamped plasmons, or decline and then vanish in the strong interband e-h excitations. Germanene, silicene and graphene are quite different from one another in the main features of the diverse plasmon modes.
Observation of multistep Coulomb excitation during ion-atom collisions
Well below the Coulomb barrier energies two colliding nuclei may share the energy via electromagnetic interactions and it can lead to excite the nuclear states of one or both the participating nuclei. This long range Coulombic interaction leading to nuclear excitation is called Coulomb excitation. In the present work, we have studied heavy ion induced Coulomb excitation process in 12C nuclei at the sub-Coulomb barrier energies using x-ray spectroscopy technique in combination with the nuclear techniques.
Vala, L
2003-09-01
The NEMO3 detector was designed for the study of double beta decay and in particular to search for the neutrinoless double beta decay process (0{nu}{beta}{beta}). The intended sensitivity in terms of a half-life limit for the 0{nu}{beta}{beta} decay is of the order of 10{sup 25} y which corresponds to an effective neutrino mass m{sub {nu}} on the level of (0.3 - 0.1) eV. The 0{nu}{beta}{beta} process is today the most promising test of the Majorana nature of the neutrino. The detector was constructed in the Modane Underground Laboratory (LSM) in France by an international collaboration including France, Russia, the Czech Republic, the USA, the UK, Finland, and Japan. The experiment has been taking data since May 2002. The quantity of {sup 100}Mo in the detector (7 kg) allows an efficient measurement of the two-neutrino double beta decay (2{nu}{beta}{beta}) of {sup 100}Mo to the excited 0{sub 1}{sup +} state (eeN{gamma} channel). Monte-Carlo simulations of the effect and of all the relative sources of background have been produced in order to define a set of appropriate selection criteria. Both Monte-Carlo simulations and special runs with sources of {sup 208}Tl and {sup 214}Bi showed that the only significant background in the eeN{gamma} channel comes from radon that penetrated inside the wire chamber of NEMO3. The experimental data acquired from May 2002 to May 2003 have been analysed in order to determine the signal from the 2{nu}{beta}{beta} decay of {sup 100}Mo to the excited 0{sub 1}{sup +} state and the corresponding background level. The physical result, which was obtained at the level of four standard deviations, is given in the form of an interval of half-life values at 95% confidence level: [5.84*10{sup 20}, 2.26*10{sup 21}] y for method A and [5.83*10{sup 20}, 1.71*10{sup 21}] y for method B. (author)
Measurement of the 2νββ decay of 100Mo to the excited 01+ state in the NEMO3 experiment
The NEMO3 detector was designed for the study of double beta decay and in particular to search for the neutrinoless double beta decay process (0νββ). The intended sensitivity in terms of a half-life limit for the 0νββ decay is of the order of 1025 y which corresponds to an effective neutrino mass mν on the level of (0.3 - 0.1) eV. The 0νββ process is today the most promising test of the Majorana nature of the neutrino. The detector was constructed in the Modane Underground Laboratory (LSM) in France by an international collaboration including France, Russia, the Czech Republic, the USA, the UK, Finland, and Japan. The experiment has been taking data since May 2002. The quantity of 100Mo in the detector (7 kg) allows an efficient measurement of the two-neutrino double beta decay (2νββ) of 100Mo to the excited 01+ state (eeNγ channel). Monte-Carlo simulations of the effect and of all the relative sources of background have been produced in order to define a set of appropriate selection criteria. Both Monte-Carlo simulations and special runs with sources of 208Tl and 214Bi showed that the only significant background in the eeNγ channel comes from radon that penetrated inside the wire chamber of NEMO3. The experimental data acquired from May 2002 to May 2003 have been analysed in order to determine the signal from the 2νββ decay of 100Mo to the excited 01+ state and the corresponding background level. The physical result, which was obtained at the level of four standard deviations, is given in the form of an interval of half-life values at 95% confidence level: [5.84*1020, 2.26*1021] y for method A and [5.83*1020, 1.71*1021] y for method B. (author)
Coulomb excitation of radioactive {sup 79}Pb
Lister, C.J.; Blumenthal, D.; Davids, C.N. [and others
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.
Multiple Coulomb excitation experiment of 68Zn
Coulomb excitation experiment was carried out with a 68Zn beam bombarding a natPb target. Two E2 matrix elements and the quadrupole moment of the 21+ state were newly derived with the least-squares search code GOSIA. The potential energy surface (PES) was calculated with the Nilsson-Strutinsky model, showing two shallow minima: the first minimum does not contain the 1g9/2 orbit below the Fermi surface, while the second minimum does. The ground state band and the intruder band seem to be constructed on the first and the second minimum, respectively. As for the ground state band, the asymmetric rotor model and the IBM in O(6) limit reproduced the experimental values rather well. The shallow PES may suggest instability of the shape. The ground state band structure may be explained assuming a soft triaxial deformation
The Coulomb excitation experiment to study electromagnetic properties of the heaviest stable Mo isotope, 100Mo, was performed using a 76 MeV 32S beam from the Warsaw cyclotron U-200P. Magnitudes and relative signs of 26 E1, E2, E3, and M1 matrix elements coupling nine low-lying states in 100Mo were determined using the least-squares code GOSIA. Diagonal matrix elements (related to the spectroscopic quadrupole moments) of the 2+1, 2+2, and 2+3 states as well as the 4+1 state were extracted. The resulting set of reduced E2 matrix elements was complete and precise enough to obtain, using the quadrupole sum rules approach, quadrupole deformation parameters of 100Mo in its two lowest 0+ states: ground and excited. The overall deformation of the 0+1 and 0+2 states in 100Mo is of similar magnitude, in both cases larger compared to what was found for the neighboring isotopes 96Mo and 98Mo. At the same time, the asymmetry parameters obtained for both states strongly differ, indicating a triaxial shape of the 100Mo nucleus in the ground state and a prolate shape in the excited 0+ state. Low-energy quadrupole excitations of the 100Mo nucleus were studied in the frame of the general quadrupole collective Bohr Hamiltonian model (GBH). The potential energy and inertial functions were calculated using the adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) method starting from two possible variants of the Skyrme effective interaction: SIII and Sly4. The overall quadrupole deformation parameters resulting from the GBH calculations with the SLy4 variant of the Skyrme interaction are slightly closer to the experimentally obtained values than those obtained using SIII. (authors)
Vibrational motions in rotating nuclei studied by Coulomb excitations
Shimizu, Yoshifumi R. [Kyushu Univ., Fukuoka (Japan). Dept. of Physics
1998-03-01
As is well-known Coulomb excitation is an excellent tool to study the nuclear collective motions. Especially the vibrational excitations in rotating nuclei, which are rather difficult to access by usual heavy-ion fusion reactions, can be investigated in detail. Combined with the famous 8{pi}-Spectrometer, which was one of the best {gamma}-ray detector and had discovered some of superdeformed bands, such Coulomb excitation experiments had been carried out at Chalk River laboratory just before it`s shutdown of physics division. In this meeting some of the experimental data are presented and compared with the results of theoretical investigations. (author)
Coulomb excitation studies of shape coexistence in atomic nuclei
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.
Characterizing intra-exciton Coulomb scattering in terahertz excitations
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
Intermediate-energy Coulomb excitation of Fe-52
Yurkewicz, KL; Bazin, D.; Brown, BA; Campbell, CM; Church, JA; Dinca, DC; A. Gade; Glasmacher, T.(National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI, 48824, United States); Honma, M.; Mizusaki, T.; Mueller, WF; Olliver, H; Otsuka, Taka; Riley, LA; Terry, Jr., Jeffrey H.
2004-01-01
The nucleus 52 Fe with s N = Z =26 d has been investigated using intermediate-energy Coulomb excitation in inverse kinematics. A reduced transition probability of B s E 2;0 1 + ! 2 1 + d = 817 s 102 d e 2 fm 4 to the first excited 2 + state at 849.0 ( 5 ) keV was deduced. The increase in excitation strength B s E 2 " d with respect to the even-mass neighbor 54...
Dynamic polarization effects in Coulomb excitation
In this paper we discuss the excitation of a quantum harmonic system, such as a particle bound in a harmonic oscillator potential, by means of dipole and quadrupole electric fields, focusing on effects of their interference. We obtain an exact solution to this problem with methods that date back to the ideas of Wigner. We discuss the rich class of dynamic polarization effects that are involved in such excitation processes and which are relevant to stopping theory, and electromagnetic excitation of atomic and nuclear systems
Coulomb excitation of the N=50 nucleus 80Zn
van de Walle, Jarno; Aksouh, Farouk; Ames, F.; Behrens, Thomas; Bildstein, V.; Blazhev, A.; Cederkall, Joakim; Clement, Emmanuel; Cocolios, Thomas Elias; Davinson, T.; Delahaye, Pierre; Eberth, J.; Ekstrom, Andreas; Fedorov, Dima V; Fedosseev, Valentin N.
2008-01-01
Neutron rich Zinc isotopes, including the N = 50 nucleus 80Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2+ states. For the first time, an excited state in 80Zn was observed and the 21+ state in 78Zn was established. The measured B(E2,21+->01+) values are compared to two sets of large scale shell model calcula...
Coulomb excitation of a 78Rb radioactive beam
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 78Rb and Coulomb re-excited it. The beam was produced in the fusion evaporation reaction 24Mg(58Ni,3pn)78Rb 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 78Kr and 78Rbgs,m1,m2, which was refocused onto a 58Ni secondary target. They have extracted a spectrum of γ-rays associated with re-excitation of A = 78 isobars. The re-excitation of stable 78Kr was observed, which serves as a reference. Gamma-rays associated with excitation of 78Rbgs,m1,m2 were also seen. The measured yields indicate that all the 78Rb states are highly deformed
Probing the quadrupole collectivity of 128Cd using Coulomb excitation
128Cd is only two proton and two neutron holes away from the doubly magic nucleus 132Sn. The excitation energy of the first excited 2+-state decreases when approaching the neutron shell closure. This unexpected behaviour makes this nucleus interesting for investigation. So far, contradicting theoretical predictions for the B(E2,0+ → 2+) value of 128Cd exist. While shell model calculations conclude an almost spherical shape of 128Cd, beyond mean field calculations predict an already considerable quadrupole collectivity. In this contribution the experimental details of the Coulomb excitation of 128Cd at REX-ISOLDE, investigated with MINIBALL (experiment IS477), are presented. Furthermore the current status of the analysis to determine the transition strength of the ground state into the first excited 2+ state is shown.
Coulomb excitation of a 78Rb radioactive beam
We have produced a secondary radioactive beam of 78Rb and Coulomb re-excited it. The beam was produced in the reaction 24Mg(58Ni,3pn)78Rb at a beam energy of 260 MeV, using the ANL 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 78Kr and 78Rbgs,m1,m2, which was refocused onto a 58Ni secondary target. We have extracted a spectrum of γ-rays associated with re-excitation of A=78 isobars. The re-excitation of stable 78Kr was observed, which serves as a reference. γ-rays associated with excitation of 78Rbgs,m1,m2 were also seen. The measured yields indicate that all the 78Rb states are highly deformed. copyright 1998 American Institute of Physics
Coulomb excitation effects on alpha-particle optical potential below the Coulomb barrier
Avrigeanu, V; Mănăilescu, C
2016-01-01
A competition of the low-energy Coulomb excitation (CE) with the compound nucleus (CN) formation in alpha-induced reactions below the Coulomb barrier has recently been assumed in order to make possible the description of the latter as well as the alpha-particle emission by the same optical model (OM) potential. On the contrary, we show in the present work that the corresponding partial waves and integration radii provide evidence for the distinct account of the CE cross section and OM total-reaction cross section $\\sigma_R$. Thus the largest contribution to CE cross section comes by far from partial waves larger than the ones contributing to the $\\sigma_R$ values.
Coulomb Excitation of the N = 50 nucleus 80Zn
Neutron rich Zinc isotopes, including the N = 50 nucleus 80Zn, were produced and post-accelerated at the Radioactive Ion Beam (RIB) facility REX-ISOLDE (CERN). Low-energy Coulomb excitation was induced on these isotopes after post-acceleration, yielding B(E2) strengths to the first excited 2+ states. For the first time, an excited state in 80Zn was observed and the 21+ state in 78Zn was established. The measured B(E2,21+→01+) values are compared to two sets of large scale shell model calculations. Both calculations reproduce the observed B(E2) systematics for the full Zinc isotopic chain. The results for N = 50 isotones indicate a good N = 50 shell closure and a strong Z = 28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni
Bauer, H.
1998-12-31
The scattering system {sup 162}Dy {yields} {sup 116}Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high {gamma}-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in {sup 162}Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)
Aspects of nuclear collectivity studied in projectile Coulomb excitation experiments
Möller, Thomas
2014-01-01
Projectile Coulomb excitation experiments have been performed on the nuclei 130,132Ba, 154Sm, and 194,196Pt. A detailed description of the experiments and the data analysis is given. The results on absolute decay rates of the low-lying collective states of these nuclei allow for a comparison with predictions from different theoretical models of nuclear quadrupole collectivity. For the nucleus 154Sm the data on the decay rates of the states of the first K=0 band support the assignment of this ...
Multiple Coulomb excitation experiment of sup 6 sup 6 Zn
Koizumi, M; Oshima, M; Osa, A; Kimura, A; Hatsukawa, Y; Shizuma, T; Hayakawa, T; Matsuda, M; Katakura, J; Seki, A; Czosnyka, T; Sugawara, M; Morikawa, T; Kusakari, H
2003-01-01
A Coulomb excitation experiment was carried out with a sup 6 sup 6 Zn beam bombarding a sup n sup a sup t Pb target. Four E2 matrix elements and the quadrupole moment of the 2 sub 1 sup + state were derived with the least-squares search code GOSIA. According to the B(E2) values, the ground band can be interpreted as a quasirotational band. It was found that the 2 sub 1 sup + level has a positive quadrupole moment, which may be interpreted as a soft triaxial deformation.
Dynamic polarization potential for heavy-ion scattering induced by multiple Coulomb excitation
In heavy-ion reactions the strong electromagnetic interactions lead to Coulomb excitation effects which are superimposed on the nuclear and static-Coulomb forces. In elastic scattering these effects can be accounted for by a long-range dynamic 'Coulomb polarization potential'. For rather heavy ions, multiple Coulomb excitation becomes important. Here the authors report on a polarization potential which takes such multiple processes into account (at least in the semi-classical approximation). (orig./AH)
Coulomb and nuclear excitations of narrow resonances in 17Ne
J. Marganiec
2016-08-01
Full Text Available 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 O15+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.
Coulomb and nuclear excitations of narrow resonances in 17Ne
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.
On the analysis of intermediate energy Coulomb excitation experiments
Scheit, Heiko; Gade, Alexandra; Glasmacher, Thomas; Motobayashi, Tohru
2008-01-01
In a recent publication [C.A. Bertulani, G. Cardella, M. De Napoli, G. Raciti, E. Rapisarda, Phys. Lett. B 650 (2007) 233] the validity of analysis methods used for intermediate-energy Coulomb excitation experiments was called into question. Applying a refined theory large corrections of results in the literature seemed needed. We show that this is not the case and that the large deviations observed in above mentioned reference are due to the use of the wrong experimental parameters in that publication. We furthermore show that an approximate expression derived in above mentioned reference is in fact equivalent to the theory of Winther and Alder, an analysis method often used in the literature.
Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation
Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others
1998-03-01
In the Coulomb excitation of {sup 155}Gd with heavy projectiles, {sup 32}S, {sup 58}Ni and {sup 90}Zr, unexpectedly large enhancement of a positive-parity side band has been observed. This enhancement could not be reproduced by a Coulomb-excitation calculation taking into account the recommended upper limits of E1 or E3 transitions, which are compiled in the whole mass region, and is proportional to the electric field accomplished in the Coulomb-scattering process. (author)
Study of the N=40 shell by using Coulomb excitation
Two Coulomb excitation experiments on neutron rich exotic nuclei have been performed at GANIL. They allowed the measurement of the reduced transition probability B(E2) (from ground state to first excited state) of some nuclei around N = 40. This number, 40, is a half-magic number in the shell model. For nuclei with an important neutron excess, it is predicted that the shell closure is stronger at N = 40. The B(E2) is a good tool for testing this growing. We have measured, by using the LISE3 spectrometer and a γ multidetector, B(E2) of 68Ni, 66Ni and 72Zn, unknown till now. We have used for the first time segmented germanium 'clovers' detector, for photon detection (v/c∼0.3). Results confirm the strong shell effect for 68Ni. Indeed 68Ni was shown to be the Nickel isotope with the lowest value of B(E2), and hence the most rigid isotope. Nevertheless it seems that the shell effect at N = 40 decreases rapidly, for other isotopes very close to 68Ni(Z = 28) and N = 40). (authors)
Tilted Foils Nuclear Spin Polarization and Measurement with Coulomb Excitation
Törnqvist, Hans; Kowalska, M; Wenander, F
2012-01-01
Developing new experimental tools is essential to expand the possibilities of probing the structure of atomic nuclei. The better the currently known properties of nuclei can be manipulated, the more information can be extracted from data collected in nuclear reaction experiments. One property that has been controlled for many years is the nuclear spin, but this has only been viable for a certain set of isotopes with restrictions on for example specific atomic excitation schemes or half-lives. This thesis will provide details on an evaluation project using thin tilted foils after the REX-ISOLDE linac at the CERN-ISOLDE experimental facility, to polarize the spin of nuclei in-flight. The nuclear polarization is then measured with a technique based on Coulomb excitation, which is a flexible and readily available experimental method at ISOLDE with the MINIBALL spectrometer. The tilted foils technique may be beneficial to polarize the nuclear spin of short-lived radioactive beams that can be difficult by other mea...
Shape determination in Coulomb excitation of $^{72}$Kr
Reiter, P; Kruecken, R; Paul, E S; Wadsworth, R; Heenen, P
Nuclei with oblate shapes at low spins are very special in nature because of their rarity. Both theoretical and experimental shape co-existence studies in the mass 70 region for near proton drip-line nuclei suggest $^{72}$Kr to be the unique case with oblate low-lying and prolate high-lying levels. However, there is no direct experimental evidence in the literature to date for the oblate nature predicted for the first 2$^+$ state in $^{72}$Kr. We propose to determine the sign of the spectroscopic quadrupole moment of this state via the re-orientation effect in a low-energy Coulomb excitation measurement. In the inelastic excitation of the 2$^+$ state in $^{72}$Kr beam of 3.1 MeV/u with an intensity of 800 pps at REX-ISOLDE impinging on $^{104}$Pd target, the re-orientation effect plays a significant role. The cross section measurement for the 2$^+$ state should thus allow the model-independent determination of the sign of the quadrupole moment unambiguously and will shed light on the co-existing prolate and o...
Using a liquid argon ionization chamber, the 2νββ decay of 100 Mo was detected with its half-life of (7.5 ± 1.1(stat.) ± 1.5(syst.)) · 1018 y. The limits on half-lives for the 0ν and 0νχ0 decays of 100Mo were estimated as 9.3(5.0) · 1021 and 4.3(2.7) · 1020 y respectively at 68 % (90%) C.L. Available world data for the 2νββ decay of 100Mo lead to the average 'world' value of the half-life, T1/2 = (8.0 ± 0.7) · 1018 y, which corresponds to the nuclear matrix element, MGT = 0.118 ± 0.005
Cold chemistry with electronically excited Ca+ Coulomb crystals
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 (coll>/kB=5-243 K). Low kinetic energy ensembles of 40Ca+ 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 40Ca+ 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 (2S1/2) and the combined excited states (2D3/2 and 2P1/2) of 40Ca+. 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.
Cold chemistry with electronically excited Ca+ Coulomb crystals
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.
In three chapters different physical situations are described which have commonly the Coulomb interaction as driving force. The first two chapters study the Coulomb interactions in connection with the excitation of inner electron shells and the Coulomb excitation of nuclei in first order. In the third part on effect ofthe Coulomb interaction between electronic shell and nucleus is treated in second order (nuclear polarization), and its effect on the isotopic and isomeric shift is studied. (orig./HSI)
Benchmark experiment for the cross section of the 100Mo(p,2n)99mTc and 100Mo(p,pn)99Mo reactions
Takács, S.; Ditrói, F.; Aikawa, M.; Haba, H.; Otuka, N.
2016-05-01
As nuclear medicine community has shown an increasing interest in accelerator produced 99mTc radionuclide, the possible alternative direct production routes for producing 99mTc were investigated intensively. One of these accelerator production routes is based on the 100Mo(p,2n)99mTc reaction. The cross section of this nuclear reaction was studied by several laboratories earlier but the available data-sets are not in good agreement. For large scale accelerator production of 99mTc based on the 100Mo(p,2n)99mTc reaction, a well-defined excitation function is required to optimise the production process effectively. One of our recent publications pointed out that most of the available experimental excitation functions for the 100Mo(p,2n)99mTc reaction have the same general shape while their amplitudes are different. To confirm the proper amplitude of the excitation function, results of three independent experiments were presented (Takács et al., 2015). In this work we present results of a thick target count rate measurement of the Eγ = 140.5 keV gamma-line from molybdenum irradiated by Ep = 17.9 MeV proton beam, as an integral benchmark experiment, to prove the cross section data reported for the 100Mo(p,2n)99mTc and 100Mo(p,pn)99Mo reactions in Takács et al. (2015).
A semiclassical estimate of the Coulomb excitation of the giant dipole resonance in 208 Pb
A semiclassical approach to study pure Coulomb excitation of 208 Pb giant dipole isovector resonance is examined. Medium energy projectiles are considered and also the target excitation to be described by a simple Goldhaber-Teller model is assumed. It is shown that the main features concerning the angular distribution are obtained in the angular range described by the model and an estimate is made of the pure Coulomb dipole contribution to the measured cross sections. (author)
The giant-dipole-resonance effect in coulomb excitation of 10B
Coulomb excitation of the 0.718-MeV, Jsup(π) = 1+, first excited state of 10B has been studied using projectile excitation by 208Pb and observing the backward scattered particles. The results give a clear indication of the virtual excitation of the giant dipole resonance as a second-order effect. The observed magnitude is consistent with the usual hydrodynamic model estimate and with a recent shell-model calculation
Gagnon, Katherine, E-mail: kgagnon1@ualberta.ca [Edmonton PET Centre, Cross Cancer Institute, University of Alberta, Edmonton, AB (Canada); Benard, Francois [BC Cancer Agency, Vancouver, BC (Canada); Kovacs, Michael [Lawson Health Research Institute, London, ON (Canada); Ruth, Thomas J.; Schaffer, Paul [TRIUMF, Vancouver, BC (Canada); Wilson, John S.; McQuarrie, Steve A. [Edmonton PET Centre, Cross Cancer Institute, University of Alberta, Edmonton, AB (Canada)
2011-08-15
Introduction: The cyclotron-based {sup 100}Mo(p,2n){sup 99m}Tc transformation has been proposed as a viable alternative to the reactor based {sup 235}U(n,f){sup 99}Mo{yields}{sup 99m}Tc strategy for production of {sup 99m}Tc. Despite efforts to theoretically model the amount of ground-state {sup 99g}Tc present at end of bombardment for the (p,2n) reaction, experimental validation has yet to be performed. The co-production of {sup 99g}Tc may have important implications in both the subsequent radiopharmaceutical chemistry and patient dosimetry upon injection. Methods: To determine the extent of {sup 99g}Tc co-production, we have experimentally measured the {sup 100}Mo(p,x){sup 99}Mo, {sup 99m}Tc, and {sup 99g}Tc excitation functions in the 8-18 MeV range using a combination of natural abundance and 97.42% enriched {sup 100}Mo foils along with {gamma}-ray spectrometry and ICP-MS. Although the excitation functions for production of {sup 99}Mo and {sup 99m}Tc have been presented previously in the literature, to the best of our knowledge, this work presents the first experimental evaluation of the {sup 100}Mo(p,2n){sup 99g}Tc excitation function. Results: From the experimental cross-section measurements, the {sup 99m}Tc production yields and {sup 99m}Tc/{sup 99m+g}Tc nuclei ratio were calculated for various thick target irradiation conditions. Results suggest that TBq quantities of {sup 99m}Tc can be achieved with a {sup 99m}Tc/{sup 99m+g}Tc nuclei ratio that is on par with the current {sup 99}Mo/{sup 99m}Tc generator standard eluted at a 24-h frequency. Conclusion: These findings suggest that the cyclotron production of {sup 99m}Tc may be a feasible alternative to the current reactor-based production strategy.
Multipole matrix elements for Coulomb excitation of rotation aligned brand in 164Er
The possibility of exciting high spin states of the rotation-aligned band is studied. A microscopic model has been employed to estimate large l multipole matrix elements for transitions to high spin states. Possible multipole Coulomb excitation paths are given. Large l multipole transitions to high spin states by inelastic proton scattering are studied. (author). 19 refs., 4 figs
Covariant formulation of Coulomb excitation in heavy ion collisions at ultra relativistic energies
Derivation of Coulomb excitation cross sections at relativistic energies is presented for the case where both projectile and target are considered as extended objects. Cross sections for projectile and/or target excitations are calculated as a function of bombarding energy in the context of a covariant theory. Several systems are analyzed and compared with available data. (author)
Intermediate-Energy Coulomb excitation of 28,29,30,31Na
The neutron-rich radioactive isotopes 28,29,30,31Na have been produced by nuclear fragmentation of 48Ca and 40Ar primary beams at intermediate energies. The energies and excitation cross sections to the lowest excited states were measured via intermediate-energy Coulomb excitation on a 197Au target. Experimental results suggest a large degree of collectivity in 31Na. Intrinsic ground state and transition quadrupole moments in 28,29,30,31Na are compared
Probing single-particle and collective states in atomic nuclei with Coulomb excitation
DiJulio, Douglas
A series of experiments and developments, related to stable and radioactive isotopes, have been carried out. These studies have focused on measuring the low-lying excitations of spherical and deformed nuclei using electromagnetic (Coulomb) excitation and also on developments in detector technology for upcoming radioactive ion beams facilities. The low-lying excitations in the nuclei 107,109Sn and 107In have been investigated using low-energy Coulomb excitation at the REX-ISOLDE facility at CERN. The measured reduced transition probabilities were compared to predictions of nuclear structure models. In addition, a relativistic Coulomb excitation experiment was carried out using the FRS at GSI with the nucleus 104Sn. These radioactive ion beam experiments provide important constraints for large-scale-shell-model calculations in the region of the doubly magic nucleus 100Sn. A stable Coulomb excitation experiment was also carried out in order to explore the properties of low-lying structures in the nucleus 170Er...
Determination of nuclear reduced transition probabilities by 7Li ion induced Coulomb excitation
Recently the authors observed that the first excited state of 7Li nucleus was excited in 7Li ion-Cu collision in the energy range 4.9 to 11.9 MeV, and the excitation process was via Coulomb excitation. By using the well known B (E2; g.s. 3-/2 - 478 keV, 1-/2) value of 7Li nucleus and the 7Li induced Coulomb excitation yields of both 7Li projectile and targets, the authors determined the reduced transition probabilities for low-lying states of some medium weight nuclei. The reduced transition probabilities determined this way are free from uncertainties due to target thickness and incident particle collection
Contribution to the study of collective states of heavy nuclei by means of coulomb excitation
The following nuclei were excited by protons of 5 MeV maximum energy: 182W - 184W - 186W - 186Os - 188Os - 189Os - 190Os - 192Os - 194Pt - 196Pt - 198Pt - 198Hg - 200Hg - 202Hg - 204Hg - 206Pb. The reduced probabilities of the various transitions were deduced from the coulomb excitation cross-section measurements. For some even-even nuclei two 2 + levels were excited. The properties of the excited levels are interpreted in terms of the collective model. (author)
Probing Shape Coexistence in neutron-deficient $^{72}$ Se via Low-Energy Coulomb Excitation
We propose to study the evolution of nuclear structure in neutron-deficient $^{72}$Se by performing a low-energy Coulomb excitation measurement. Matrix elements will be determined for low-lying excited states allowing for a full comparison with theoretical predictions. Furthermore, the intrinsic shape of the ground state, and the second 0$^{+}$ state, will be investigated using the quadrupole sum rules method.
Giant Resonances in Coulomb Excitations of Relativistic Ions
Hussein, M. S.; Piza, A. F. R. de Toledo; Vorov, O. K.
1999-01-01
We propose a soluble model to incorporate the nonlinear effects in the transition probabilities of the multiphonon Giant Dipole Resonances based on the SU(1,1) algebra. Analytical expressions for the multi-phonon transition probabilities are derived. For reasonably small magnitude of nonlinearity $x\\simeq 0.1-0.2$ enhancement factor for the Double Giant Resonance excitation probabilities and the cross sections %in relativistic ion collisions reaches values $1.3-2$ compatible with experimental...
Coulomb and nuclear excitations of narrow resonances in 17Ne
Marganiec, J.; Wamers, F.; Aksouh, F.; Yu. Aksyutina; 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.
2016-01-01
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 O15+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 ...
Coulomb excitation of the two proton-hole nucleus $^{206}$Hg
We propose to use Coulomb excitation of the single magic two-proton-hole nucleus $^{206}$Hg. In a single-step excitation both the first 2$^{+}$ and the highly collective octupole 3$^{-}$ states will be populated. Thus, information on both quadrupole and octupole collectivity will be gained in this neutron-rich nucleus. Due to the high beam intensity, we will be able to observe multi-step Coulomb excitation as well, providing further test on theoretical calculations. The results will be used to improve the predictive power of the shell model for more exotic nuclei as we move to lighter N=126 nuclei. The experiment will use the new HIE-ISOLDE facility and the MINIBALL array, and will take advantage of the recently developed $^{206}$Hg beam from the molten lead target.
Coulomb Excitation of Neutron Deficient Sn-Isotopes using REX-ISOLDE
Di julio, D D; Kownacki, J M; Marechal, F; Andreoiu, C; Siem, S; Perrot, F; Van duppen, P L E; Napiorkowski, P J; Iwanicki, J S
2002-01-01
It is proposed to study the evolution of the reduced transition probabilities, B(E2; 0$^{+} \\rightarrow$ 2$^{+}$), for neutron deficient Sn isotopes by Coulomb excitation in inverse kinematics using REX-ISOLDE and the MINIBALL detector array. Measurements of the reduced transition matrix element for the transition between the ground state and the first excited 2$^{+}$ state in light even-even Sn isotopes provide a means to study e.g. core polarization effects in the $^{100}$Sn core. Previous attempts to measure this quantity have been carried out using the decay of isomeric states populated in fusion evaporation reactions. We thus propose to utilize the unique opportunity provided by REX-ISOLDE, after the energy upgrade to 3.1 MeV/u, to use the more model-independent approach of Coulomb excitation to measure this quantity in a number of isotopes in this region.
Probing intruder configurations in $^{186, 188}$Pb using Coulomb excitation
Columb excitation measurements to study the shape coexistence, mixing and quadrupole collectivity of the low-lying levels in neutron-deficient $^{188}$Pb nuclei are proposed with a view to extending similar studies to the $^{186}$Pb midshell nucleus. The HIE-ISOLDE beam of $^{186,188}$Pb nuclei will be delivered to MINIBALL+SPEDE set-up for simultaneous in-beam $\\gamma$-ray and conversion electron spectroscopy. The proposed experiment will allow the sign of the quadrupole deformation parameter to be extracted for the two lowest 2$^{+}$ states in $^{188}$Pb. Moreover, the advent of SPEDE will allow probing of the bandhead 0$^{+}$ states via direct measurements of E0 transitions. Beam development is requested to provide pure and instense $^{186}$Pb beam.
Coulomb excitation of exotic nuclei at the R3B-LAND setup
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)%.
Coulomb excitation of neutron-rich $^{134-136}$Sn isotopes
We propose to study excited states in the isotopes $^{134,136}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to investigate the evolution of quadrupole collectivity beyond the magic shell closure at N = 82 by the determination of B(E2) values and electric quadrupole moments $\\mathcal{Q}_2$. Recent shell-model calculations using realistic interactions predict possible enhanced collectivity in neutron-rich regions. Evidence for this could be obtained by this experiment. Furthermore, the currently unknown excitation energies of the 2$^+_{1}$ and 4$^+_{1}$ states in $^{136}$Sn will be measured for the first time.
The light krypton isotopes show two minima in their potential energy corresponding to elongated (prolate) and compressed (oblate) quadrupole deformation. Both configuration are almost equally bound and occur within an energy range of less than 1 MeV. Such phenomenon is called shape coexistence. An inversion of the ground state deformation from prolate in Kr78 to oblate in Kr72 with strong mixing of the configurations in Kr74 and Kr76 was proposed based on the systematic of isotopic chain. Coulomb excitation experiments are sensitive to the quadrupole moment. Coulomb excitation experiments of radioactive Kr74 and Kr76 beam were performed at GANIL using the SPIRAL facility and the EXOGAM spectrometer. The analysis of these experiments resulted in a complete description of the transition strength and quadrupole moments of the low-lying states. They establish the prolate character of the ground state and an oblate excited state. A complementary lifetime measurement using a 'plunger' device was also performed. Transition strength in neighboring nuclei were measured using the technique of intermediate energy Coulomb excitation at GANIL. The results on the Se68 nucleus show a sharp change in structure with respects to heavier neighboring nuclei. (author)
Probing core polarization around 78Ni: intermediate energy Coulomb excitation of 74Ni
Marchi T.
2013-12-01
We have recently measured the B(E2; 0+ → 2+ of the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment performed at the National Superconducting Cyclotron Laboratory of the Michigan State University. The 74Ni secondary beam has been produced by fragmentation of 86Kr at 140 AMeV on a thick Be target. Selected radioactive fragments impinged on a secondary 197Au target where the measurement of the emitted γ-rays allows to extract the Coulomb excitation cross section and related structure information. Preliminary B(E2 values do not point towards an enhancement of the transition matrix element and the comparison to what was already measured by Aoi and co-workers in [1] opens new scenarios in the interpretation of the shell evolution of the Z=28 isotopes.
Onset of collectivity in $^{96,98}$Sr studied via Coulomb excitation
Clement, E; Dijon, A; de France, G; Bastin, B; Blazhev, A; Bree, N; Butler, P; Delahaye, P; Ekstrom, A; Georgiev, G; Hasan, N; Iwanicki, J; Jenkins, D; Korten, W; Larsen, A C; Ljungvall, J; Moschner, K; Napiorkowski, P; Pakarinen, J; Petts, A; Renstrom, T; Seidlitz, M; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Warr, N; Wrzosek-Lipska, K; Zielinska, M; Bauer, C; Bruyneel, B; Butterworth, J; Fitzpatrick, C; Fransen, C; GernhäUser, R; Hess, H; Lutter, R; Marley, P; Reiter, P; Siebeck, B; Vermeulen, M; Wiens, A; De Witte, H
2014-01-01
A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N=60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.
Onset of collectivity in 96,98Sr studied via Coulomb excitation
Clément E.
2014-03-01
Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N=60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.
Kumar, Rajiv; Sharma, Shagun [DAV University, Physics Department, Jalandhar (India); Singh, Pradeep [Deenbandhu Chhotu Ram University of Science and Technology, Department of Physics, Murthal (India); Kharab, Rajesh [Kurukshetra University, Department of Physics, Kurukshetra (India)
2016-02-15
The energy-independent touching spheres schemes commonly used for the determination of the safe minimum value of the impact parameter for Coulomb excitation experiments are modified through the inclusion of an energy-dependent term. The touching spheres+3fm scheme after modification emerges out to be the best one while touching spheres+4fm scheme is found to be better in its unmodified form. (orig.)
The energy-independent touching spheres schemes commonly used for the determination of the safe minimum value of the impact parameter for Coulomb excitation experiments are modified through the inclusion of an energy-dependent term. The touching spheres+3fm scheme after modification emerges out to be the best one while touching spheres+4fm scheme is found to be better in its unmodified form. (orig.)
Shape coexistence in the neutron-deficient mercury isotopes studied through Coulomb excitation
Bree, Nick
This thesis describes the analysis and results of a series of Coulomb-excitation experiments on even-even neutron-deficient mercury isotopes aimed at obtaining a more detailed description of shape coexistence. Two experimental campaigns have been undertaken in the Summer of 2007 and 2008. Pure beams of 182,184,186,188Hg were produced and accelerated at the REX-ISOLDE radioactive-beam facility, located at CERN (Geneva, Switzerland). The beams were guided to collide with a stable target to induce Coulomb excitation. The scattered particles were registered by a double-sided silicon strip detector, and the emitted gamma rays by the MINIBALL gamma-ray spectrometer. The motivation to study these mercury isotopes, focused around shape coexistence in atomic nuclei, is addressed in chapter 1, as well as an overview of the knowledge in this region of the nuclear chart. A theoretical description of Coulomb excitation is presented in the second chapter, while the third chapter describes the setup employed for the experim...
Testing refined shell-model interactions in the sd shell: Coulomb excitation of Na26
Siebeck, B; 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
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 sd interaction (USD) describing nuclei within the sd 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 Na26 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 Na26 (T1/2=1,07s) 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...
Coulomb excitation of re-accelerated 208Rn and 206Po beams
In the present study, B(E2; 2+ → 0+) values have been measured in the 208Rn and 206Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. The resulting B(E2; 2+ → 0+) in 208Rn is ∼ 0.08 e2b2. These nuclei lie in, or at the boundary of the region where seniority scheme should persist. However, contributions from collective excitations may be present when moving away from the N = 126 shell closure. To date, surprisingly little is known of the transition probabilities between the low-spin states in this region. (authors)
Bastin, B; Kruecken, R; Larsen, A; Rahkila, P J; Srebrny, J; Clement, E; Wadsworth, R; Syed naeemul, H; Peura, P J; Siem, S; Hadynska-klek, K; Habs, D; Page, R; Napiorkowski, P J; Diriken, J V J; Iwanicki, J S
Coulomb excitation measurements to study the shape coexistence and quadrupole collectivity of the low-lying levels in neutron-deficient Pb nuclei are proposed. Even-mass $^{188−192}$Pb nuclei will be post-accelerated at REX-ISOLDE in order to measure transition probabilities and quadrupole moments for the first excited states. In combination with results obtained in lifetime measurements, this will allow the sign of the quadrupole deformation parameter to be extracted for the first time for 2$^{+}$ states in the even-mass $^{188−192}$Pb nuclei.
N. Andres; Catara, F.; Lanza, E. G.; Chomaz, Ph.; FALLOT M.; Scarpaci, J.A.
2001-01-01
We calculate the inelastic scattering cross sections to populate one- and two-phonon states in heavy ion collisions with both Coulomb and nuclear excitations. Starting from a microscopic approach based on RPA, we go beyond it in order to treat anharmonicities and non-linear terms in the exciting field. These anharmonicities and non-linearities are shown to have important effects on the cross sections both in the low energy part of the spectrum and in the energy region of the Double Giant Quad...
Electromagnetic properties of sup 1 sup 6 sup 5 Ho inferred from Coulomb excitation
Iwanicki, J; Czosnyka, T; Choinski, J; Napiorkowski, P J; Loewe, M; Wuerkner, M; Srebrny, J
2003-01-01
The nucleus sup 1 sup 6 sup 5 Ho was Coulomb excited using sup 1 sup 6 O, sup 2 sup 0 Ne and sup 4 sup 0 Ar beams from the Warsaw Cyclotron. A model-independent analysis using the GOSIA code yielded a set of 26 reduced E2 matrix elements and 12 M1 matrix elements coupling the 13 low-lying excited states. A quadrupole sum rules approach was used to determine the deformation of the states. A remarkable change of the quadrupole deformation in one of the gamma-vibrational bands was found.
Dynamical Coupling of Pygmy and Giant Resonances in Relativistic Coulomb Excitation
Brady, N; Bertulani, C A; Thomas, J
2016-01-01
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 a 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.
Intermediate-energy Coulomb excitation of 104Sn: Moderate E2 strength decrease approaching 100Sn
Doornenbal, P; Aoi, N; Matsushita, M; Obertelli, A; Steppenbeck, D; Wang, H; Audirac, L; Baba, H; Bednarczyk, P; Boissinot, S; Ciemala, M; Corsi, A; Furumoto, T; Isobe, T; Jungclaus, A; Lapoux, V; Lee, J; Matsui, K; Motobayashi, T; Nishimura, D; Ota, S; Pollacco, E C; Sakurai, H; Santamaria, C; Shiga, Y; Sohler, D; Taniuchi, R
2013-01-01
The reduced transition probability B(E2) of the first excited 2+ state in the nucleus 104Sn was measured via Coulomb excitation in inverse kinematics at intermediate energies. A value of 0.163(26) e^2b^2 was extracted from the absolute cross-section on a Pb target, while the method itself was verified with the stable 112Sn isotope. Our result deviates significantly from the earlier reported value of 0.10(4) e^2b^2 and corresponds to a moderate decrease of excitation strength relative to the almost constant values observed in the proton-rich, even-A 106-114Sn isotopes. Present state-of-the-art shell-model predictions, which include proton and neutron excitations across the N=Z=50 shell closures as well as standard polarization charges, underestimate the experimental findings
Q value of the 100Mo Double-Beta Decay
Rahaman, S; Eronen, T; Hakala, J; Jokinen, A; Julin, J; Kankainen, A; Saastamoinen, A; Suhonen, J; Weber, C; Äystö, J
2007-01-01
Penning trap measurements using mixed beams of 100Mo - 100Ru and 76Ge - 76Se have been utilized to determine the double-beta decay Q-values of 100Mo and 76Ge with uncertainties less than 200 eV. The value for 76Ge, 2039.04(16) keV is in agreement with the published SMILETRAP value. The new value for 100Mo, 3034.40(17) keV is 30 times more precise than the previous literature value, sufficient for the ongoing neutrinoless double-beta decay searches in 100Mo. Moreover, the precise Q-value is used to calculate the phase-space integrals and the experimental nuclear matrix element of double-beta decay.
Fusion of 60Ni + 100Mo below barrier
Greene J.P.
2011-10-01
Full Text Available The fusion cross section of 60Ni + 100Mo has been measured down to microbarn level, looking for hindrance at low energy, in a system with positive Q-values for neutron transfer. The measured cross sections look similar to those of the nearby 64Ni + 100Mo, but no conclusive statement can be made at this stage, as to the onset of hindrance in this system.
Structure of low-lying states in 140Sm studied by Coulomb excitation
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.
The structure of low-lying states in ${}^{140}$Sm studied by Coulomb excitation
Klintefjord, M; Görgen, A; Bauer, C; Garrote, F L Bello; 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
2016-01-01
The electromagnetic structure of $^{140}$Sm 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 multi-step 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 $2_1^+$ 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 $^{140}$Sm shows considerable $\\gamma$ 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 collectivit...
Coulomb excitation of neutron-rich odd-$A$ Cd isotopes
Reiter, P; Kruecken, R; Gernhaeuser, R A; Kroell, T; Leske, J; Marginean, N M
We propose to study excited states in the odd-${A}$ isotopes $^{123,125,127}$Cd by ${\\gamma}$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to determine the B(E2) values connecting excited states with the ground state as well as the long-lived (11/2$^{-}$) isomer. The proposed study profits from the unique capability of ISOLDE to produce beams containing Cd in the ground state or in the isomeric state. Our recent results on the neutron-rich even-A Cd nuclei appear to show that these nuclei may possess some collectivity beyond that calculated by modern shell-model predictions. Beyond-mean-field calculations also predict these nuclei to be weakly deformed. These facets are surprising considering their proximity to the doubly magic $^{132}$Sn. Coulomb-excitation studies of odd-${A}$ Cd isotopes may give a unique insight into the deformation-driving roles played by different orbits in this region. Such studies of the onset of collectivity become especially important in light of recent...
Coulomb excitation of $^{182-184}$ Hg: Shape coexistence in the neutron-deficient lead region
We put forward a study of the interplay between individual nucleon behavior and collective degrees of freedom in the nucleus, as manifested in shape coexistence in the neutrondeficient lead region. As a first step of this experimental campaign, we propose to perform Coulomb excitation on light mercury isotopes to probe their excited states and determine transitional and diagonal E2 matrix elements, especially reducing the current uncertainties. The results from previous Coulomb excitation measurements in this mass region performed with 2.85 MeV/u beams from REX-ISOLDE have shown the feasibility of these experiments. Based on our past experience and the results obtained, we propose a detailed study of the $^{182-184}$Hg nuclei, that exhibit a pronounced mixing between low-lying excited states of 2 apparently different deformation character, using the higher energy beams from HIE-ISOLDE which are crucial to reach our goal. The higher beam energy should result in an increased sensitivity with respect to the quad...
Measurement of excitation functions in 16O + 93Nb at energies above the Coulomb barrier
From past few decades it has become the topic of great interest to study heavy ion (HI) induced reaction at intermediate energy range. It has been observed that at energies just above the Coulomb barrier both the complete fusion (CF) and incomplete fusion (ICF) reaction may dominant. In CF processes whole projectile fuses with the target while in ICF processes only a part of projectile fuses with the target and remaining part passes with almost beam energy. Some studies show that ICF competes with CF just above the Coulomb barrier. Several theoretical models have been presented to explain the ICF reaction dynamics, such as Exciton model, Breakup fusion model, Promptly emitted particles model, Multistep direct reaction theory and Hot spot model etc. In the present work an effort has been made to investigate the mechanism involve in HI reaction with measurement of excitation functions for thirteen evaporation residues (ERs) identified in the interaction of 16O+93Nb system.
Zhou Zhao-Yan; Yuan Jian-Min
2007-01-01
Response of the wave packet of a one-dimensional Coulomb atom to an intense laser field is calculated using the symmetrized split operator fast Fourier method.The high-order harmonic generation (HHG) of the initial state separately being the ground and excited states is presented.When the hardness parameter α in the soft Coulomb potential V(x) =-1/(x2+α) is chosen to be small enough,the so-called hard Coulomb potential V(x) =-1/|x| can be obtained.It is Well knawn that the hard one-dimensional Coulomb atom has an unstable ground state with an energy eigenvalue of ～0.5 and it has no states corresponding to physical states in the true atoms,and has the first and second excited states being degenerate.The parity effects on the HHG can be seen from the first and second excited states of the hard one-dimensional Coulomb atom.The HHG spectra of the excited states from both the soft and hard Coulomb atom models are shown to have more complex structures and to be much stronger than the corresponding HHG spectrum of the ground state of the soft Coulomb model with α=2 in the same laser field.Laser-induced non-resonant one-photon emission is also observed.
Determination of absolute transition probabilities in 128Xe via projectile Coulomb excitation
Recently, lifetimes of low-lying excited states in 128Xe were measured using the plunger technique after projectile Coulomb excitation. This experiment was performed at the JYFL, Jyvaeskylae using the JUROGAM Ge-detector array and the Cologne coincidence plunger device equipped with an array of 32 small Si-detectors. The Si-detectors were used to measure the reaction kinematics by registering target-like nuclei scattered in forward direction. In order to cross-check the results obtained from the recoil distance Doppler shift analysis an evaluation of the measured excitation cross-sections was performed with the computer code GOSIA. In addition deorientation effects were investigated and effort was made to extract absolute quadrupole moments. Details of the experiment and the calculations are presented.
Low-energy Coulomb excitation of neutron-rich zinc isotopes
At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,21+→01+) values in 74-80Zn, B(E2,41+→21+) values in 74,76Zn and the determination of the energy of the first excited 21+ states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, including a recent empirical residual interaction constructed to describe the present experimental data up to 2004 in this region of the nuclear chart
Coulomb Excitation of 68,70Cu First Use of Postaccelerated Isomeric Beams
Stefanescu, I
2007-01-01
We report on the first low-energy Coulomb excitation measurements with radioactive Iπ=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. γ rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the π2p3/2ν1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6-→4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N≈40.
Low-energy Coulomb excitation of neutron-rich zinc isotopes
Van de Walle, J; Behrens, T; Bildstein, V; Blazhev, A; Cederkäll, J; Clément, E; Cocolios, T E; Davinson, T; Delahaye, P; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V; Fraile, L M; Franchoo, S; Gernhäuser, R; Georgiev, G; Habs, D; Heyde, K; Huber, G; Huyse, M; Ibrahim, F; Ivanov, O; Iwanicki, J; Jolie, J; Kester, O; Köster, U; Kröll, T; Krücken, R; Lauer, M; Lisetskiy, A F; Lutter, R; Marsh, B A; Mayet, P; Niedermaier, O; Pantea, M; Raabe, R; Reiter, P; Sawicka, M; Scheit, H; Schrieder, G; Schwalm, D; Seliverstov, M D; Sieber, T; Sletten, G; Smirnova, N; Stanoiu, M; Stefanescu, I; Thomas, J C; Valiente-Dobón, J J; Van Duppen, P; Verney, D; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Wolf, B H; Zielinska, M
2009-01-01
At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,20) values in 74-80Zn, B(E2,42) values in 74,76Zn and the determination of the energy of the first excited 2 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, i...
Dipole-strength distributions below the giant dipole resonance in 92Mo, 98Mo and 100Mo
Investigations of the dipole-strength distributions in 92Mo, 98Mo and 100Mo were carried out by means of the method of nuclear resonance fluorescence. The low-lying excitations in the nuclides 92Mo, 98Mo and 100Mo have been studied in photon-scattering experiments at an electron energy of 6 MeV at the ELBE accelerator and at electron energies from 3.2 to 3.8 MeV at the Dynamitron accelerator. Five levels were observed in 92Mo. Five levels in 98Mo and 14 in 100Mo were identified for the first time in the energy range from 2 to 4 MeV. Dipole-strength distributions up to the neutron-separation energies in the nuclides 92Mo, 98Mo and 100Mo have been investigated at the ELBE accelerator. Because of the possible observation of transitions in the neighboring nuclei produced via (γ,n) reaction, additional measurements at electron energies of 8.4 and 7.8 MeV, below the neutron-separation energy, were performed on 98Mo and 100Mo, respectively. The number of transitions assigned to 92Mo, 98Mo and 100Mo is 340, 485 and 499, respectively, the main part of them being dipole transitions. Statistical properties of the observed transitions are obtained. The continuum contains the ground-state transitions as well as the branching transitions to the low-lying levels and the subsequent deexcitations of these levels. (orig.)
Measurements of shape co-existence in $^{182,184}$Hg using Coulomb excitation
Voulot, D; Paul, E S; Siem, S; Czosnyka, T; Napiorkowski, P J; Iwanicki, J S
2007-01-01
We propose to exploit the unique capability of ISOLDE to provide post-accelerated $^{182,184}$Hg ions from the REX facility to enable the lowest states of these nuclei to be Coulomb excited. By measuring the $\\gamma$-ray yields using the MINIBALL array we can measure the transition and diagonal E2 matrix elements for these states. This will give quantitative information about the nature of the shape coexistence in these nuclei and allow the sign of the quadrupole deformation be determined for the first time. We require 24 shifts to fulfill the aims of the experiment.
Coulomb excitation of exotic nuclei at REX-ISOLDE with MINIBALL
In this contribution nuclear structure studies with post-accelerated radioactive ion beams from the REX-ISOLDE facility at CERN are presented. The method employed is γ-ray spectroscopy with the MINIBALL array following 'safe' Coulomb excitation. The highly efficient MINIBALL array consists of 8 triple clusters of six-fold segmented HPGe detectors. Recent results concerning the investigation of nuclear shapes are presented and discussed. These results include studies on deformation in 94,96Kr nuclei, on quadrupole collectivity around 132Sn, on shape coexistence in neutron-deficient Hg, Po and Rn isotopes, and on octupole states in 122Rn and 224Ra nuclei
SU(2,1) Dynamics of Multiple Giant Dipole Resonance Coulomb Excitation
Hussein, M S; Vorov, O K
2000-01-01
We construct a three-dimensional analytically soluble model of the nonlinear effects in Coulomb excitation of multiphonon Giant Dipole Resonances (GDR) based on the SU(2,1) algebra. The full 3-dimensional model predicts further enhancement of the Double GDR (DGDR) cross sections at high bombarding energies. Enhancement factors for DGDR measured in thirteen different processes with various projectiles and targets at different bombarding energies are well reproduced with the same value of the nonlinearity parameter with the exception of the anomalous case of $^{136}$Xe which requires a larger value.
A nonlinear electromagnetic energy harvester directly powering a load resistance is considered in this manuscript. The nonlinearity includes the cubic stiffness and the unavoidable Coulomb friction, and the base excitation is confined to Gaussian white noise. Directly starting from the coupled equations, a novel procedure to evaluate the random responses and the mean output power is developed through the generalized harmonic transformation and the equivalent non-linearization technique. The dependence of the optimal ratio of the load resistance to the internal resistance and the associated optimal mean output power on the internal resistance of the coil is established. The principle of impedance matching is correct only when the internal resistance is infinity, and the optimal mean output power approaches an upper limit as the internal resistance is close to zero. The influence of the Coulomb friction on the optimal resistance ratio and the optimal mean output power is also investigated. It is proved that the Coulomb friction almost does not change the optimal resistance ratio although it prominently reduces the optimal mean output power. (paper)
Do nuclei go pear-shaped? Coulomb excitation of 220Rn and 224Ra at REX-ISOLDE (CERN
Scheck M.
2015-01-01
Full Text Available 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.
Evolution of collectivity in the 78Ni region: Coulomb excitation of 74Ni at intermediate energies.
Marchi T.
2014-03-01
Full Text Available The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic observables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope (64Ni towards the 78Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently performed an experiment with the goal to extract the B(E2; 0+ → 2+ value for the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.
Coulomb Excitation of a Neutron-Rich $^{88}$Kr Beam Search for Mixed Symmetry States
Andreoiu, C; Napiorkowski, P J; Iwanicki, J S
2002-01-01
We propose to use the ISOLDE/REX/MINIBALL/CD set-up to perform a Coulomb Excitation experiment with a $^{88}$Kr radioactive beam. The motivation includes a search for $Mixed$ $Symmetry$ states predicted by the IBM-2 model, gathering more spectroscopy data about the $^{88}$Kr nucleus and extending shape coexistence studies (performed previously by the proposers for neutron-deficient Kr isotopes) to the neutron-rich side. The proposed experiment will provide data complementary to the Coulomb Excitation of a relativistic $^{88}$Kr beam proposed by D. Tonev et al. for a RISING experiment. A total of 12 days of beam time is necessary for the experiment, equally divided into two runs. One run with a 2.2 MeV/A beam energy on a $^{48}$Ti target and a second run with the maximum available REX energy of 3.1 MeV/A on a $^{208}$Pb target are requested. Using either a UC$_{x}$ or ThC$_{x}$ fissioning primary target coupled with a plasma source by a cooled transfer line seems to be the best choice for the proposed experime...
Probing core polarization around 78Ni: Intermediate energy Coulomb excitation of 74Ni
The study of the evolution of nuclear shells far from stability provides fundamental information about the shape and symmetry of the nuclear mean field. Nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Of particular interest is the region of 78Ni where the large neutron excess coincides with a double shell closure. We have recently measured the B(E2; 0+ → 2+) of the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment performed at the National Superconducting Cyclotron Laboratory of the Michigan State University. The 74Ni secondary beam has been produced by fragmentation of 86Kr at 140 AMeV on a thick Be target. Selected radioactive fragments impinged on a secondary 197Au target where the measurement of the emitted γ-rays allows to extract the Coulomb excitation cross section and related structure information. Preliminary B(E2) values do not point towards an enhancement of the transition matrix element and the comparison to what was already measured by Aoi and co-workers in [1] opens new scenarios in the interpretation of the shell evolution of the Z=28 isotopes. (authors)
Coulomb excitation of the odd-odd isotopes $^{106, 108}$In
Ekstrom, A; Blazhev, A; Van de Walle, J; Weisshaar, D; Zielinska, M; Tveten, G M; Marsh, B A; Siem, S; Gorska, M; Engeland, T; Hurst, A M; Cederkall, J; Finke, F; Iwanicki, J; Hjorth-Jensen, M; Davinson, T; Eberth, J; Sletten, G; Mierzejewski, J; Reiter, P; Warr, N; Butler, P A; Fahlander, C; Stefanescu, I; Koester, U; Ivanov, O; Wenander, F; Voulot, D
2010-01-01
The low-lying states in the odd-odd and unstable isotopes In-106,In-108 have been Coulomb excited from the ground state and the first excited isomeric state at the REX-ISOLDE facility at CERN. With the additional data provided here the pi g(9/2)(-1) circle times nu d(5/2) and pi g(9/2)(-1) circle times nu g7/2 multiplets have been re-analyzed and are modified compared to previous results. The observed gamma-ray de-excitation patterns were interpreted within a shell model calculation based on a realistic effective interaction. The agreement between theory and experiment is satisfactory and the calculations reproduce the observed differences in the excitation pattern of the two isotopes. The calculations exclude a 6(+) ground state in In-106. This is in agreement with the conclusions drawn using other techniques. Furthermore, based on the experimental results, it is also concluded that the ordering of the isomeric and ground state in In-108 is inverted compared to the shell model prediction. Limits on B(E2) val...
Level lifetimes and quadrupole moments from Coulomb excitation in the Ba chain
Bauer, Christopher; Guastalla, Giulia; Leske, Joerg; Moeller, Thomas; Pietralla, Norbert; Stahl, Christian; Stegmann, Robert; Wiederhold, Johannes [Technische Univ. Darmstadt (Germany). Inst. fuer Kernphysik; Seweryniak, Darek; Zhu, Shaofei [Argonne National Lab., Chicago, IL (United States); Collaboration: IS411-Collaboration
2013-07-01
The chain of Barium isotopes enables us to study experimentally the evolution of nuclear quadrupole collectivity from the shell closure at N=82 towards neutron-deficient or neutron-rich deformed nuclei. The TU Darmstadt group has investigated several nuclei from stable {sup 130,132}Ba up to radioactive {sup 140,142}Ba with the projectile-Coulomb excitation technique including the use of the Doppler-shift attenuation method (DSAM). Lifetimes of quadrupole-collective states of {sup 132}Ba and {sup 140}Ba were obtained for the first time as well as the static electric quadrupole moments Q(2{sup +}{sub 1}) for {sup 130,132}Ba and {sup 140,142}Ba. The results are compared to Monte Carlo shell model and Beyond-Mean-Field calculations.
Kugler, E; Ratzinger, U; Wenander, F J C
2002-01-01
% IS347 \\\\ \\\\We propose to perform a pilot experiment to study very neutron rich (A<32) Na-Mg and (A<52) K-Ca isotopes in the region around the neutron shell closures of N=20 and N=28 after Coulomb excitation and neutron transfer, and to demonstrate highly efficient and cost-effective ways to bunch, charge-state breed and accelerate already existing mass-separated singly-charged radioactive ion beams. \\\\ \\\\To do this we plan to accelerate the ISOLDE beams up to 2~MeV/u by means of a novel acceleration scheme and to install an efficient $\\gamma$-ray array for low-multiplicity events around the target position.
Structure studies on 82Kr by means of the multiple Coulomb excitation
With a 82Kr beam of the energy 4.6 MeV per nucleon a 208Pb target was irradiated in order to study the Coulomb excitation of 82Kr. The experiment has been performed at the Society for Heavy Ion Research (GSI) in Darmstadt. The 82Kr ions backscattered on the 208Pb target were detected in a position-sensitive parallel-plate avalanche detector. The γ radiation of the excited 82Kr particles was detected in 4 Ge(Li) detectors in coincidence with the particles. The spectra corrected regarding the Doppler shift contained 16 lines which permitted to determine by means of known mixing and branching ratios 22 electrical quadrupole transition matrix elements. The experimental excitation energies and the transition probabilities determined in this thesis are compared with different nuclear models, like the asymmetric rotator model, the rotational-vibrational model, the harmonic-oscillator model, the nuclear field theory, the SU(5) limit of the IBA-1, and the IBA-2 model. Thereby within the IBA-2 model a criterium for the symmetry of the wavefunction relative to the proton and neutron contributions is elaborated. Because of this criterium to the 21+ state a symmetric structure and to the 22+,3 states an asymmetric structure is assigned. (orig.)
Transfer Reactions and Multiple Coulomb Excitation in the $^{100}$Sn Region
It is proposed to continue our REX-ISOLDE program in the $^{100}$Sn region at HIE-ISOLDE at ~5 MeV/u. Earlier measurements, with a precision of 10-20%, at 3 MeV/u with REX-ISOLDE point to a deviation between the measured B(E2) values for the first excited 2$^{+}$ states in $^{110,108,106}$Sn compared to theoretical predictions. In addition, the trend of B(E2) values for the lighter isotopes, in particular $^{106}$Sn, appear to differ between low- and high-energy measurements. In line with our letter-of-intent we aim in a first step to address the electromagnetic properties of the first 2$^{+}$and 4$^{+}$ states in $^{110,108,106}$Sn using Coulomb excitation. In these measurements we will directly access the life time of the first excited 4$^{+}$ states in $^{110,108,106}$Sn for the first time. The yield of $^{104}$Sn from the LaC$_{x}$ target will be revisited to clarify if the new solid state RILIS gives sufficient yield to expand the measurements to this isotope. Following this proposal we plan similar meas...
Collectivity in the light radon nuclei measured directly via Coulomb excitation
Gaffney, L P; Jenkins, D G; Andreyev, A N; Bender, M; Blazhev, A; Bree, N; Bruyneel, B; Butler, P A; Cocolios, T E; Davinson, T; Deacon, A N; De Witte, H; DiJulio, D; Diriken, J; Ekström, A; Fransen, Ch; Freeman, S J; Geibel, K; Grahn, T; Hadinia, B; Hass, M; Heenen, P -H; Hess, H; Huyse, M; Jakobsson, U; Kesteloot, N; Konki, J; Kröll, Th; Kumar, V; Ivanov, O; Martin-Haugh, S; Mücher, D; Orlandi, R; Pakarinen, J; Petts, A; Peura, P; Rahkila, P; Reiter, P; Scheck, M; Seidlitz, M; Singh, K; Smith, J F; Van de Walle, J; Van Duppen, P; Voulot, D; Wadsworth, R; Warr, N; Wenander, F; Wimmer, K; Wrzosek-Lipska, K; Zielińska, M
2015-01-01
Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around $Z=82$ and the neutron mid-shell at $N=104$. Purpose: Evidence for shape coexistence has been inferred from $\\alpha$-decay measurements, laser spectroscopy and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of $^{202}$Rn and $^{204}$Rn were studied by means of low-energy Coulomb excitation at the REX-ISOLDE facility in CERN. Results: The electric-quadrupole ($E2$) matrix element connecting the ground state and first-excited $2^{+}_{1}$ state was extracted for both $^{202}$Rn and $^{204}$Rn, corresponding to ${B(E2;2^{+}_{1} \\to 2^...
We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when ℎω > Ip: it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with ℎω p: new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)
An experimental investigation of double beta decay of 100Mo
New limits on half-lives for several double beta decay modes of 100Mo were obtained with a novel experimental system which included thin source films interleaved with a coaxial array of windowless silicon detectors. Segmentation and timing information allowed backgrounds originating in the films to be studied in some detail. Dummy films containing 96Mo were used to assess remaining backgrounds. With 0.1 mole years of 100Mo data collected, the lower half-life limits at 90% confidence were 2.7 /times/ 1018 years for decay via the two-neutrino mode, 5.2 /times/1019 years for decay with the emission of a Majoron, and 1.6 /times/ 1020 years and 2.2 /times/ 1021 years for neutrinoless 0+ → 2+ and 0+ → 0+ transitions, respectively. 50 refs., 38 figs., 11 tabs
Coulomb dissociation reactions on molybdenum isotopes for astrophysics applications
Ershova, Olga
2012-03-09
Within the present work, photodissociation reactions on {sup 100}Mo, {sup 93}Mo and {sup 92}Mo isotopes were studied by means of the Coulomb dissociation method at the LAND setup at GSI. As a result of the analysis of the present experiment, integrated Coulomb excitation cross sections of the {sup 100}Mo({gamma},n), {sup 100}Mo({gamma},2n), {sup 93}Mo({gamma},n) and {sup 92}Mo({gamma},n) reactions were determined. A second important topic of the present thesis is the investigation of the efficiency of the CsI gamma detector. The data taken with the gamma calibration sources shortly after the experiment were used for the investigation. In addition, a test experiment in refined conditions was conducted within the framework of this thesis. Numerous GEANT3 simulations of the detector were performed in order to understand various aspects of its performance. As a result, the efficiency of the detector was determined to be approximately a factor of 2 lower than the efficiency expected from the simulation. (orig.)
A study of the evolution of the nuclear structure along the zinc isotopic chain close to the doubly magic nucleus $^{78}$Ni is proposed to probe recent shell-model calculations in this area of the nuclear chart. Excitation energies and connecting B(E2) values will be measured through multiple Coulomb excitation experiment with laser ionized purified beams of $^{74-80}$Zn from HIE ISOLDE. The current proposal request 30 shifts.
Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation
Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O
We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.
Shape coexistence in neutron-rich Sr isotopes : Coulomb excitation of $^{96}$Sr
Clement, E; Siem, S; Czosnyka, T
2007-01-01
The nuclei in the mass region A $\\cong$ 100 around Sr and Zr show a dramatic change of the nuclear ground-state shape from near spherical for N $\\leq$ 58 to strongly deformed for N $\\geq$ 60. Theoretical calculations predict the coexistence of slightly oblate and strongly prolate deformed configurations in the transitional region. However, excited rotational structures based on the highly deformed configuration, which becomes the ground state at N = 60, are not firmly established in the lighter isotopes, and the earlier interpretation of a very abrupt change of shape has been challenged by recent experimental results in favor of a rather gradual change. We propose to study the electromagnetic properties of the neutron-rich nucleus $_{38}^{96}$Sr$_{58}$ by low-energy Coulomb excitation using the REX-ISOLDE facility and the MINIBALL detector array. Both transitional and diagonal matrix elements will be extracted, resulting in a complete description of the transition strengths and quadrupole moments of the low-l...
Coulomb excitation of doubly magic $^{132}$Sn with MINIBALL at HIE-ISOLDE
We propose to study the vibrational first 2$^{+}$ and 3$^{-}$ states of the doubly magic nucleus $^{132}$ Sn via Coulomb excitation using the HIE-ISOLDE facility coupled with the highly efficient MINIBALL array. The intense $^{132}$Sn beam at ISOLDE, the high beam energy of HIE-ISOLDE, the high energy resolution and good efficiency of the MINIBALL provide a unique combination and favourable advantages to master this demanding measurement. Reliable B(E2;0$^{+}\\rightarrow$ 2$^{+}$) values for neutron deficient $^{106,108,110}$Sn were obtained with the MINIBALL at REX-ISOLDE. These measurements can be extended up to and beyond the shell closure at the neutron-rich side with $^{132}$Sn. The results on excited collective states in $^{132}$Sn will provide crucial information on 2p-2h cross shell configurations which are expected to be dominated by a strong proton contribution. Predictions are made within various large scale shell model calculations and new mean field calculations within the framework of different a...
Mixing of Triaxial and Intruder Configurations in 72,76Ge Studied via Multistep Coulomb Excitation
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.
Spin distribution measurement for 64Ni + 100Mo at near and above barrier energies
Singh Varinderjit
2015-01-01
Full Text Available Spin distribution measurements were performed for the reaction 64Ni + 100Mo at three beam energies ranging from 230 to 260 MeV. Compound nucleus (CN spin distributions were obtained channel selective for each evaporation residue populated by the de-excitation cascade. A comparison of the spin distribution at different beam energies indicates that its slope becomes steeper and steeper with increasing beam energy. This change in slope of the spin distribution is mainly due to the onset of fission competition with particle evaporation at higher beam energies.
Rusev, G.Y.
2006-07-01
Investigations of the dipole-strength distributions in {sup 92}Mo, {sup 98}Mo and {sup 100}Mo were carried out by means of the method of nuclear resonance fluorescence. The low-lying excitations in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been studied in photon-scattering experiments at an electron energy of 6 MeV at the ELBE accelerator and at electron energies from 3.2 to 3.8 MeV at the Dynamitron accelerator. Five levels were observed in {sup 92}Mo. Five levels in {sup 98}Mo and 14 in {sup 100}Mo were identified for the first time in the energy range from 2 to 4 MeV. Dipole-strength distributions up to the neutron-separation energies in the nuclides {sup 92}Mo, {sup 98}Mo and {sup 100}Mo have been investigated at the ELBE accelerator. Because of the possible observation of transitions in the neighboring nuclei produced via ({gamma},n) reaction, additional measurements at electron energies of 8.4 and 7.8 MeV, below the neutron-separation energy, were performed on {sup 98}Mo and {sup 100}Mo, respectively. The number of transitions assigned to {sup 92}Mo, {sup 98}Mo and {sup 100}Mo is 340, 485 and 499, respectively, the main part of them being dipole transitions. Statistical properties of the observed transitions are obtained. The continuum contains the ground-state transitions as well as the branching transitions to the low-lying levels and the subsequent deexcitations of these levels. (orig.)
Coulomb excitation of giant resonances in 208Pb by E = 84 MeV/nucleon 17O projectiles
Inelastic scattering of 84 MeV/nucleon 17O on 208Pb has been measured between 1.50 ≤ θCM ≤ 5.00. The giant resonance structure near 12 MeV is excited with a differential cross section of more than 2b/sr and exhibits a peak-to-continuum ratio as large as 6 to 1. The major part of the cross section can be ascribed to Coulomb excitation of the isovector giant dipole and the giant quadrupole resonance. From the Coulomb excitation of the GQR we deduce a B(E2)↑ = 0.53±0.11 e2b2 which is that expected for a nearly pure isoscalar resonance which exhausts ≅ 60% of the EWSR. (orig.)
Tao, C; Zhang, G Q; Cao, X G; Fang, D Q; Wang, H W; Xu, J
2013-01-01
The isoscalar giant monopole resonance (ISGMR) in Sn isotopes and other nuclei has been investigated by Coulomb excitations in the framework of the isospin-dependent quantum molecular dynamics (IQMD) model. The spectrum of GMR has been calculated by taking the root-mean-square (RMS) radius of a nucleus as its monopole moment. The peak energy, the full width at half maximum (FWHM), and the strength of GMR extracted by a Gaussian fit to the spectrum have been studied. The GMR peak energies for Sn isotopes from the calculations using a mass-number dependent Gaussian wave-packet width $\\sigma_r$ for nucleons are found to be overestimated and show a weak dependence on the mass number compared with the experimental data. However, it has been found that experimental data of the GMR peak energies for $^{40}$Ca, $^{56}$Ni, $^{90}$Zr and $^{208}$Pb as well as Sn isotopes can be nicely reproduced after taking into account the isospin dependence in isotope chains in addition to the mass number dependence of $\\sigma_r$ fo...
Preparation of actinide targets by molecular plating for coulomb excitation studies at ATLAS
Greene, J P; Ahmad, I
1999-01-01
Molecular plating is now routinely used to prepare sources and targets of actinide elements. Although the technique is simple and fairly reproducible, because of the radioactive nature of the targets, it is very useful to record various parameters in the preparation process. At Argonne, approx 200 mu g/cm sup 2 thick targets of Pu and Cm were required for Coulomb Excitation (COULEX) studies with the Argonne-Notre Dame boron germanate (BGO) gamma-ray facility and later with the GAMMASPHERE. These targets were plated on 50 mg/cm sup 2 Au backings and were covered with 150 mu g/cm sup 2 Au foil. Targets of sup 2 sup 3 sup 9 Pu, sup 2 sup 4 sup 0 Pu, sup 2 sup 4 sup 2 Pu, sup 2 sup 4 sup 4 Pu and sup 2 sup 4 sup 8 Cm were prepared by dissolving the material in isopropyl alcohol and electroplating the actinide ions by applying 600 V. The amount of these materials on the target was determined by alpha particle counting and gamma-ray counting. Details of the molecular plating and counting will be discussed.
A 98% pure 242mAm (K=5-, t1/2=141 years) isomeric target was Coulomb excited with a 170.5-MeV 40Ar 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/2π) in at least four rotational bands; 11 of these new states lie in the isomer band, 13 in a previously unknown yrast Kπ=6- rotational band, and 13 in a band tentatively identified as the predicted yrast Kπ=5+ band. The rotational bands based on the Kπ=5- isomer and the 6- bandhead were populated by Coulomb excitation with unexpectedly equal cross sections. The γ-ray yields are reproduced by Coulomb excitation calculations using a two-particle plus rotor model (PRM), implying nearly complete ΔK=1 mixing of the two almost-degenerate rotational bands, but recovering the Alaga rule for the unperturbed states. The degeneracy of the 5- and 6- 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 IKπ=66- state in the nominal 65- isomer band state is measured within the PRM as 45.6-1.1+0.3%. The E2 and M1 strengths coupling the 5- and 6- 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+ band are reproduced by an E3 strength of ≅15 W.u., competitive with the interband E2 strength. Alignments of the identified two-particle Nilsson states in 242Am are compared with the single-particle alignments in 241Am.
Montoya, Modesto
2014-01-01
This work is focused on even-odd effects on the minimal total fragment excitation energy in thermal neutron induced fission of 233U and 235U as well as in spontaneous fission of 252Cf. In a scission model, taking into account the fragment deformation properties and Coulomb interaction between fragments, the expression of the difference between Q-values referred to even/even and odd/odd charge splits, respectively, on the corresponding difference between the minimal total fragment excitation e...
Montoya, Modesto
2014-01-01
This work is focused on even-odd effects on the minimal total fragment excitation energy in thermal neutron induced fission of 233U and 235U as well as in spontaneous fission of 252Cf. In a scission model, taking into account the fragment deformation properties and Coulomb interaction between fragments, the expression of the difference between Q-values referred to even/even and odd/odd charge splits, respectively, on the corresponding difference between the minimal total fragment excitation energy is studied.
Coulomb excitation of radioactive 132,134,136Te beams and the low B(E2) of 136Te
The B(E2;0+→2+) values for the first 2+ excited states of neutron-rich 132,134,136Te have been measured using Coulomb excitation of radioactive ion beams. The B(E2) values obtained for 132,134Te are in excellent agreement with expectations based on the systematics of heavy stable Te isotopes, while that for 136Te is unexpectedly small. These results are discussed in terms of proton-neutron configuration mixing and shell-model calculations using realistic effective interactions
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.
Low-energy Coulomb excitation of $^{62}$Fe and $^{62}$Mn following in-beam decay of $^{62}$Mn
Gaffney, L P; Bastin, B; Bildstein, V; Blazhev, A; Bree, N; Darby, I; De Witte, H; DiJulio, D; Diriken, J; Fedosseev, V N; Fransen, Ch; Gernhäuser, R; Gustafsson, A; Hess, H; Huyse, M; Kesteloot, N; Kröll, Th; Lutter, R; Marsh, B A; Reiter, P; Seidlitz, M; Van Duppen, P; Voulot, D; Warr, N; Wenander, F; Wimmer, K; Wrzosek-Lipska, K
2015-01-01
Sub-barrier Coulomb-excitation was performed on a mixed beam of $^{62}$Mn and $^{62}$Fe, following in-trap $\\beta^{-}$ decay of $^{62}$Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418 keV, which has been tentatively associated to a $2^{(+)},3^{(+)}\\rightarrow1^{+}_{g.s.}$ transition. This fixes the relative positions of the $\\beta$-decaying $4^{(+)}$ and $1^{+}$ states in $^{62}$Mn for the first time. Population of the $2^{+}_{1}$ state was observed in $^{62}$Fe and the cross-section determined by normalisation to the $^{109}$Ag target excitation. Combining this Coulomb-excitation cross-section with previously measured lifetimes of the $2^{+}_{1}$ state, the spectroscopic quadrupole moment, $Q_{s}(2^{+}_{1})$, is extracted, albeit with a large uncertainty.
Investigation of beam purity after in-trap decay and Coulomb excitation of $^{62}$Mn-$^{62}$Fe
Clement, E; Gernhaeuser, R A; Diriken, J V J; Huyse, M L
2008-01-01
The in-trap decay of short lived radioactive ions is not well understood. This poses a problem for Coulomb excitation experiments at MINIBALL, where the normalization of the experiment depends strongly on observed secondary target excitation, which in turn strongly depends on the knowledge of the beam composition. For pure ISOLDE beams of short lived isotopes, the in-trap decay becomes important since a large fraction of the beam is transformed in unwanted daughter isotopes. In this proposal we intend to quantify the production of these daughter products in the REXTRAP accurately by making use of the short lived isotopes $^{61,62}$Mn and the newly installed Bragg ionization chamber at the end of the REX linear accelerator. Apart from the technical interest, the A=62 beam provides as well a good physics case, concerning the development of collectivity in neutron-rich Fe isotopes. Coulomb excitation, utilizing the standard MINIBALL setup, is proposed on both A=62 Mn and Fe. The Fe beam would be the first post-a...
It is proposed to investigate the structure of excited states in $^{68;70}$Ni(Z = 28;N = 40; 42) via the measurement of electromagnetic matrix elements in a Coulomb excitation experiment in order to study the N = 40 harmonic-oscillator shell and the Z = 28 proton shell closures. The measured B(E2) values connecting low-lying 0$^{+}$ and 2$^{+}$ can be compared to shell-model predictions. It is also proposed to perform the one-neutron transfer reaction ${d}$($^{68}$Ni,$^{69}$Ni)${p}$, with the aim of populating excited states in$^{69}$Ni. Comparisons with the states populated in the recently performed ${d}$($^{66}$Ni,$^{67}$Ni)${p}$ reaction will be useful in determining the role of the neutron $d_{5/2}$ orbital in the semi-magic properties of $^{68}$Ni.
Measurements of octupole collectivity in $^{220,222}$Rn and $^{222,224}$Ra using Coulomb excitation
Kruecken, R; Larsen, A; Hurst, A M; Voulot, D; Grahn, T; Clement, E; Wadsworth, R; Gernhaeuser, R A; Siem, S; Huyse, M L; Iwanicki, J S
2008-01-01
We propose to exploit the unique capability of ISOLDE to provide post-accelerated $^{220,222}$Rn and $^{222,224}$Ra ion beams from the REX facility to enable the Coulomb excitation of the first 3$^{-}$ states in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^{-}$ state using the MINIBALL array we can obtain the transition matrix elements. This will give quantitative information about octupole correlations in these nuclei. We require 22 shifts to fulfil the aims of the experiment.
Seweryniak D.; Rapisarda E.; Rainovski G.; Pakarinen J.; Pietralla N.; Möller T.; Möller O.; Leske J.; Guastalla G.; Bauer C.; Stahl C.; Stegmann R.; Wiederhold J.; Zhu S.
2012-01-01
The chain of Barium isotopes enables us to study experimentally the evolution of nuclear quadrupole collectivity from the shell closure at N = 82 towards neutron-deficient or neutron-rich deformed nuclei. The TU Darmstadt group has investigated several nuclei from stable 130,132Ba up to radioactive 140,142Ba with the projectile-Coulomb excitation technique including the use of the Doppler-shift attenuation method (DSAM). Lifetimes of quadrupole-collective states of 132Ba and 140Ba were obtain...
An expression is given for the (n/sub i/,l = 0 → n/sub f/,l/sub f/ = 0) excitation cross section in terms of a single one-dimensional integral with the aid of a transformation to prolate spheroidal coordinates. Results are given for the 1s-2s excitation of arbitrary-Z hydrogenic targets. For our choice of wave functions the cross sections are found to scale as Z-4 at fixed E/sub inc//Z2. The principal difference between the Coulomb-projected Born-approximation (CPBA) and Born results is in the large-angle portion of the differential cross section. This, however, leads to CPBA and Born momentum-transfer cross sections which differ by less than 20% at high energies for 1s-2s transitions
Coulomb excitation of $^{116}$Te and $^{118}$Te: a study of collectivity above the Z = 50 shell gap
Cederkall, J A; Smith, J F; Voulot, D; Rahkila, P J; Darby, I G; Hadinia, B; Grahn, T; Paul, E S; Wadsworth, R; Bree, N C F; Baeck, T M; Julin, R J; Diriken, J V J; Jenkins, D G; Kroell, T; Leske, J; Huyse, M L
We propose to study the nature and collectivity of low-energy excitations in $^{116}$Te and $^{118}$Te. We aim to measure the transition probability of the 0$^{+}$ $\\rightarrow$ 2$^{+}$ transition by means of Coulomb excitation, employing REX-ISOLDE and MINIBALL. The proposed study probes the systematics of B(E2) values in light Te nuclei, which lie in a region of the nuclear chart where unusual phenomena and evolution of collectivity have been observed. The proposed study will shed light on the role of the residual proton-neutron interactions in the development of collectivity when approaching the N = Z line. This is a resubmission of the P-277 proposal. The suggestions of INTC have been taken into account and the data from the Yale $^{120}$Te study has been included.
Low-energy Coulomb excitation of 62Fe and 62Mn following in-beam decay of 62Mn
Sub-barrier Coulomb excitation was performed on a mixed beam of 62Mn and 62Fe, following in-trap β- decay of 62Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418 keV, which has been tentatively associated to a (2+,3+) → 1g.s.+ transition. This fixes the relative positions of the β-decaying 4+ and 1+ states in 62Mn for the first time. Population of the 21+ state was observed in 62Fe and the cross-section determined by normalisation to the 109Ag target excitation, confirming the B(E2) value measured in recoil-distance lifetime experiments. (orig.)
Excitation of pygmy dipole resonance in neutron-rich nuclei via Coulomb and nuclear fields
A Vitturi; E G Lanza; M V Andrés; F Catara; D Gambacurta
2010-07-01
We study the nature of the low-lying dipole strength in neutron-rich nuclei, often associated with the pygmy dipole resonance. The states are described within the Hartree–Fock plus RPA formalism, using different parametrizations of the Skyrme inter-action. We show how the information from combined reaction processes involving the Coulomb and different mixtures of isoscalar and isovector nuclear interactions can provide a clue to reveal the characteristic features of these states.
Andreoiu, C; Paul, E S; Czosnyka, T; Hammond, N
2002-01-01
We propose to study the Coulomb excitation of a radioactive beam of $^{70}$Se at 2.2 MeV/u obtained from the REX-ISOLDE facility in order to determine the sign of the quadrupole moment and, hence, the sign of the quadrupole deformation. Calculations suggest a 33~\\% sensitivity in Coulomb excitation yield for a nickel target depending on whether the nuclear shape is oblate or prolate. Such a determination would provide compelling evidence for the presence of oblate shapes in the vicinity of N=Z=34.
Coulomb Excitation of Odd-Mass and Odd-Odd Cu Isotopes using REX-ISOLDE and Miniball
Lauer, M; Iwanicki, J S
2002-01-01
We propose to study the properties of the odd-mass and the odd-odd neutron-rich Cu nuclei applying the Coulomb excitation technique and using the REX-ISOLDE facility coupled to the Miniball array. The results from the Coulex experiments accomplished at REX-ISOLDE after its upgrade to 3 MeV/u during the last year have shown the power of this method and its importance in order to obtain information on the collective properties of even-even nuclei. Performing an experiment on the odd-mass and on the odd-odd neutron-rich Cu isotopes in the vicinity of N=40 should allow us to determine and interpret the effective proton and neutron charges in the region and to unravel the lowest proton-neutron multiplets in $^{68,70}$Cu. This experiment can take the advantage of the unique opportunity to accelerate isomerically separated beams using the RILIS ion source at ISOLDE.
The study of the odd 99,101Ru nuclei complements the investigation of the collectivity of the first quadrupolar excitations in 100,102,104Ru. Angular distributions for the 99,101Ru(d, d') reactions at 13 MeV were obtained in the Pelletron Laboratory using nuclear emulsion plates on the focal plane of the Enge spectrograph. A Coulomb- Nuclear Interference analysis employing DWBA-DOMP predictions with global optical potential parameters was applied to the excitation of states which could belong to the multiplet built on the first quadrupolar excitation of the core. In the analysis, three states were identified for each of the isotopes and associated, respectively, with adopted levels in the Nuclear Data Sheets Compilation of Jπ = 5=2+, 7=2+ and 9=2+. Through the comparison of experimental and predicted cross section angular distributions, the values of (δLN)2 and of the ratio C = δLC /δLN were obtained. (author)
The 'Lund-York-Cologne-Calorimeter' (LYCCA) is the first operational NUSTAR device for the HiSpec experiment at FAIR. LYCCA is a high efficient ToF-ΔE-E detector array for identification and tracking of exotic nuclei. After testing and commissioning of LYCCA the successful operation of LYCCA was achieved in first in-beam γ-ray spectroscopy experiments at GSI. A Coulomb excitation experiment using a relativistic, radioactive 33Ar beam was performed employing LYCCA. The 33Ar beam, produced by impinging a primary 36Ar beam on a 9Be target, hit onto a secondary 197Au target with an energy of approximately 145 MeV/u. γ-rays were observed by the Ge Cluster detectors of the PreSpec setup. LYCCA was employed to track the outgoing ions and to reject all nuclear reaction channels. B(E2) values for excited states in 33Ar have been determined. These first experimental values for proton-rich Tz = -(3)/(2) sd shell nuclei are used to test effective interactions for new shell model calculations, describing excitation energies of sd shell mirror pairs.
Rodrigues, C.L.; Rodrigues, M.R.D.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J. L.M.; Hanninger, G.N. [Sao Paulo Univ., SP (Brazil). Inst. de Fisica; Ukita, G.M. [Universidade de Santo Amaro, SP (Brazil). Faculdade de Psicologia
2004-09-15
The study of the odd {sup 99,101}Ru nuclei complements the investigation of the collectivity of the first quadrupolar excitations in {sup 100,102,104}Ru. Angular distributions for the {sup 99,101}Ru(d, d') reactions at 13 MeV were obtained in the Pelletron Laboratory using nuclear emulsion plates on the focal plane of the Enge spectrograph. A Coulomb- Nuclear Interference analysis employing DWBA-DOMP predictions with global optical potential parameters was applied to the excitation of states which could belong to the multiplet built on the first quadrupolar excitation of the core. In the analysis, three states were identified for each of the isotopes and associated, respectively, with adopted levels in the Nuclear Data Sheets Compilation of J{pi} = 5=2{sup +}, 7=2{sup +} and 9=2{sup +}. Through the comparison of experimental and predicted cross section angular distributions, the values of ({delta}{sup L}{sub N}){sup 2} and of the ratio C = {delta}{sub L}{sup C} /{delta}{sub L}{sup N} were obtained. (author)
New limit on the neutrinoless double beta decay of 100Mo
A search for the neutrinoless double beta decay of 100Mo was conducted using thin Mo films and solid state Si detectors. The experiment has collected 3500 hours of data operating underground in a deep silver mine (3290 M.W.E.). Only one event was found to be consistent with neutrinoless double beta decay. Using this one event, a limit of ≥ 1 x 1022 years (1 σ) is set on the 100Mo half-life. This is approximately five times larger than the best previous 100Mo limit
100Mo(p, d)99Mo reaction at 50 MeV and direct reaction analysis
The 100Mo(p vector, d)99Mo reaction has been studied with 50 MeV polarized protons. Angular distribution of the differential cross section and the analyzing power have been measured for neutron hole states in the 99Mo up to the excitation energy of 6 MeV. The data analysis with a standard distorted-wave Born Approximation (DWBA) theory provides transferred angular momenta(l and j) and spectroscopic factors of neutron hole states for 40 excited states from the ground states up to the excitation energy of 3 MeV. The direct reaction model and the continuous strength functions were used to analyze spectrum regions from discrete levels to continuum. (author)
Sub-Coulomb fusion excitation function for 12 C + 12 C
Fusion excitation functions are measured for the o, p and n evaporation channels in the fusion of the 12 C + 12 C system at center of mass energies between 4.5 and 6.5 MeV, with energy steps of 75 keV. The X-ray technique is used with a new absolute normalization method which is independent of charge collection and allows at the same time to monitor the Carbon buildup on the target. Good agreement is obtained with absolute cross section values previously measured using particle detection techniques, but smaller energy steps are used in the present experiment. As in previous works much structure is seen in the excitation function which is consistent with the positions of resonances reported in the literature for this system. (Author)
Electron-capture decay of 100Tc and the double-β decay of 100Mo
We have measured the electron-capture decay branch of 100Tc to be (1.8±0.9)x10-3%, from which we deduce logft=4.45-0.30+0.18. This indicates that a two-step process connecting only the ground states of 100Mo-100Tc-100Ru can account for the measured 2ν double-β-decay rate of 100Mo
Leenhardt, St
2000-01-01
Two Coulomb excitation experiments on neutron rich exotic nuclei have been performed at GANIL. They allowed the measurement of the reduced transition probability B(E2) (from ground state to first excited state) of some nuclei around N = 40. This number, 40, is a half-magic number in the shell model. For nuclei with an important neutron excess, it is predicted that the shell closure is stronger at N = 40. The B(E2) is a good tool for testing this growing. We have measured, by using the LISE3 spectrometer and a {gamma} multidetector, B(E2) of {sup 68}Ni, {sup 66}Ni and {sup 72}Zn, unknown till now. We have used for the first time segmented germanium 'clovers' detector, for photon detection (v/c{approx}0.3). Results confirm the strong shell effect for {sup 68}Ni. Indeed {sup 68}Ni was shown to be the Nickel isotope with the lowest value of B(E2), and hence the most rigid isotope. Nevertheless it seems that the shell effect at N = 40 decreases rapidly, for other isotopes very close to {sup 68}Ni(Z = 28) and N = 40). (authors)
Coulomb Excitation of Neutron-Rich $A\\approx$140 Nuclei
Van duppen, P L E
2002-01-01
Investigating the isospin dependence of the product between the B( E2; 0$_{1}^{+} \\rightarrow 2_{1}^{+}$)-value and the 2$_{1}^{+}$-excitation energy E$_{2^{+}}$ in even-even nuclei around $A\\!\\approx$140 one observes a rather smooth trend close to the valley of stability but clear indication for a reduction from the extrapolated B(E2)-values by one order of magnitude for some very neutron-rich nuclei. While close to the valley of stability the strong neutron-proton interaction results in an equilibration of the neutron and proton deformations with a predominate isoscalar character of the collective 2$^{+}$ excitation, it is conceivable that more loosely bound neutrons cannot polarize a close-to-magic proton core that well any more. This might result in a decoupling of the shape of the outer neutrons from the core and in a strong isovector admixture to the lowest lying 2$^{+}$ level. In this way the 2$^{+}$ -energies could be further lowered in neutron-rich nuclei, while the quadrupole moments of the proton c...
Coulomb excitation of $^{94,96}$Kr beam Deformation in the neutron-rich krypton isotopes
Hass, M; Cederkall, J A; Di julio, D D; Zamfir, N - V; Srebrny, J; Wadsworth, R; Siem, S; Marginean, R; Iwanicki, J S
Recently the energy of the 2$_{1}^{+}$ state in the N=60 $^{96}$Kr nucleus was determinated to be 241 keV. This was the first experimental observation of an excited state in this highly exotic nucleus. The 2$_{1}^{+}$ state in $^{94}$Kr is located at 665.5 keV, i.e. E(2$_{1}^{+}$) drops by more than 400 keV at N=60. This lowering of the 2$_{1}^{+}$ energy indicates a sharp shape transition behavior which is somewhat similar to that discovered in the Sr and Zr isotopic chains at N=60. The deformation expected for the 2$_{1}^{+}$ state of $^{96}$Kr, as resulting from the E(2$_{1}^{+}$) energy based on the semi-empirical relation of Raman et al. is $\\beta_{2}$ = 0.31, which is, however, considerably smaller than that for Sr and Zr ($\\geq$0.40). The sudden decrease of E(2$_{1}^{+}$) from N=50 to N=60 does not fully agree with the more gradual change of deformation deduced from laser spectroscopy measurements of mean square charge radii, although for $^{96}$Kr, in particular, these are consistent with a $\\beta_{2}...
Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the 21+ State in 80Zn
Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 21+ state in 78Zn could be firmly established and for the first time the 2+→01+ transition in 80Zn was observed at 1492(1) keV. B(E2,21+→01+) values were extracted for 74,76,78,80Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni
Coulomb-nuclear interference with 6Li: Isospin character of the 21+ excitation in 70,72,74Ge
Ratios of B(E2) to B(IS2), that is, of the reduced quadrupole transition probabilities related, respectively, to charge and mass were extracted through Coulomb-nuclear interference (CNI) for the excitation of the 21+ states in 70,72,74Ge, with a relative accuracy of less than 4%. For this purpose, the CNI angular distributions associated with the inelastic scattering of 28-MeV incident 6Li ions accelerated by the Sao Paulo Pelletron, and momentum analyzed by the Enge magnetic spectrograph were interpreted within the DWBA-DOMP approach (distorted wave approximation for the scattering process and deformed optical model for the structure representation) with global 6Li optical parameters. The present CNI results demonstrate an abrupt change in the B(E2)/B(IS2) ratio for 74Ge: although for 70,72Ge, values of the order of 1.0 or slightly higher were obtained, this ratio is 0.66 (7) for 74Ge. The heavier Ge isotope is thus one of the few nuclei that, so far, have been shown to present clear mixed symmetry components in their ground-state band
The AMoRE: Search for neutrinoless double beta decay of {sup 100}Mo
Park, HyangKyu, E-mail: hkpark@ibs.re.kr [Center for Underground Physics, Institute for Basic Science (IBS), Daejeon 305-811 (Korea, Republic of)
2015-10-28
The AMoRE (Advanced Mo-based Rare process Experiment) collaboration is using calcium molybdate ({sup dep48}Ca {sup 100}MoO{sub 4}) crystals enriched in {sup 100}Mo and depleted in {sup 48}Ca to search for neutrinoless double-beta decay (DBD) of {sup 100}Mo using at the underground laboratory in Korea. Metallic magnetic calorimeters operating a milliKelvin temperatures are used as temperature sensors to measure heat and light signals from the crystals. The simultaneous and fast detection capabilities for both phonons and photons, and their excellent energy resolution provide powerful methods for identifying DBD signals and rejecting background events, which are mainly due to random coincidences between two uncorrelated two-neutrino-double-beta decays of {sup 100}Mo. The AMoRE-Pilot experiment that is currently underway uses a 1.5 kg, five-element array of {sup dep48}Ca {sup 100}MoO{sub 4} crystals. The ultimate goal is a ∼200 kg array of crystals and a half-life sensitivity of order 10{sup 26} years, which will access the inverted hierarchy region for effective Majorana neutrino masses, i.e., 0.02 to 0.05 eV. In this talk, we present recent progress on the development of low-background calcium molybdate detectors and results from room- and milli-Kelvin temperatures. Sensitivities based on GEANT4 simulations that incorporate measured background are reported.
Clément E.
2013-12-01
Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N = 60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.
We propose to exploit the unique capability of ISOLDE to provide intense post-accelerated $^{142}$Ba and $^{144}$Ba ion beams from the HIE-ISOLDE facility to enable the Coulomb excitation of the first 3$^-$ state in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^-$ state using the MINIBALL array, we can obtain the interesting transition matrix element. The results will give quantitative information about octupole correlations in these nuclei.
The double beta decay spectrum of 100Mo as measured with a TPC [time projection chamber
A time projection chamber with 8.3 grams of enriched 100MoO3 as the central electrode has been operating approximately five months in an underground laboratory. A preliminary analysis of the two-electron sum energy spectrum, the spectrum of those same electrons taken singly, and the opening angle distribution yields a half life of 1.16-0.08+0.34 x 1019 y at the 68% confidence level for two-neutrino double beta decay of 100Mo. 9 refs., 8 figs
Back, B.B.; Blumenthal, D.J.; Davids, C.N. [and others
1995-08-01
In this experiment we tried to measure the evaporation residue cross section over a wide range of beam energies for the {sup 100}Mo + {sup 116}Cd reaction using the FMA. However, because of longer-than-estimated runs needed at each beam energy, and the difficulty of bending evaporation residues at the higher energies in the FMA, data were taken only at beam energies of E{sub beam} = 460, 490, and 521 MeV, which correspond to excitation energies of E{sub exc} = 62, 78, and 95 MeV, respectively. By comparing to results for the {sup 32}S + {sup 184}W reactions measured recently, we expect to demonstrate a strong entrance channel effect related to the hindrance of complete fusion in near-symmetric heavy systems (a fusion hindrance factor of the order 7-10 is expected on the basis of the Extra-Push Model). The data are being analyzed.
Clement, E
2006-06-15
The light krypton isotopes show two minima in their potential energy corresponding to elongated (prolate) and compressed (oblate) quadrupole deformation. Both configuration are almost equally bound and occur within an energy range of less than 1 MeV. Such phenomenon is called shape coexistence. An inversion of the ground state deformation from prolate in Kr{sup 78} to oblate in Kr{sup 72} with strong mixing of the configurations in Kr{sup 74} and Kr{sup 76} was proposed based on the systematic of isotopic chain. Coulomb excitation experiments are sensitive to the quadrupole moment. Coulomb excitation experiments of radioactive Kr{sup 74} and Kr{sup 76} beam were performed at GANIL using the SPIRAL facility and the EXOGAM spectrometer. The analysis of these experiments resulted in a complete description of the transition strength and quadrupole moments of the low-lying states. They establish the prolate character of the ground state and an oblate excited state. A complementary lifetime measurement using a 'plunger' device was also performed. Transition strength in neighboring nuclei were measured using the technique of intermediate energy Coulomb excitation at GANIL. The results on the Se{sup 68} nucleus show a sharp change in structure with respects to heavier neighboring nuclei. (author)
Barabash, A.S. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Chernyak, D.M.; Poda, D.V. [Institute for Nuclear Research, MSP, Kiev (Ukraine); Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France); Danevich, F.A. [Institute for Nuclear Research, MSP, Kiev (Ukraine); Giuliani, A. [Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France); Dipartimento di Scienza e Alta Tecnologia dell' Universita dell' Insubria, Como (Italy); INFN, Sezione di Milano Bicocca, Milan (Italy); Ivanov, I.M.; Makarov, E.P.; Nasonov, S.G.; Shlegel, V.N.; Vasiliev, Ya.V. [Nikolaev Institute of Inorganic Chemistry, Novosibirsk (Russian Federation); Mancuso, M. [Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France); Dipartimento di Scienza e Alta Tecnologia dell' Universita dell' Insubria, Como (Italy); Marnieros, S.; Olivieri, E.; Tenconi, M. [Centre de Sciences Nucleaires et de Sciences de la Matiere, Orsay (France); Nones, C. [CEA-Saclay, Service de Physique des Particules, Gif-sur-Yvette (France); Pessina, G. [INFN, Sezione di Milano Bicocca, Milan (Italy); Tretyak, V.I. [Institute for Nuclear Research, MSP, Kiev (Ukraine); INFN, Sezione di Roma ' ' La Sapienza' ' , Rome (Italy); Velazquez, M. [CNRS, Universite de Bordeaux, ICMCB, Pessac (France); Zhdankov, V.N. [CML Ltd., Novosibirsk (Russian Federation)
2014-10-15
The LUMINEU project is a demonstrator experiment that will search for the neutrinoless double beta decay of the isotope {sup 100}Mo embedded in zinc molybdate (ZnMoO{sub 4}) scintillating bolometers. In this context, a zinc molybdate crystal boule enriched in {sup 100}Mo to 99.5 % with a mass of 171 g was grown for the first time by the low-thermalgradient Czochralski technique. The production cycle provided a high yield (the crystal boule mass was 84 % of the initial charge) and an acceptable level - around 4 % - of irrecoverable losses of the costly enriched material. Two crystals of 59 and 63 g, obtained from the enriched boule, were tested above ground at millikelvin temperatures as scintillating bolometers. They showed a good detection performance, equivalent to that of previously developed natural ZnMoO{sub 4} detectors. These results pave the way to future sensitive searches based on the LUMINEU technology, capable of approaching and exploring the inverted hierarchy region of the neutrino mass pattern. (orig.)
Coulomb excitation is a very precise tool to measure excitation probabilities and provide insight on the collectivity of nuclear excitations and in particular on nuclear shapes. In the last few years radioactive ion beam facilities such as HRIBF opened unique opportunities to explore the structure of nuclei in the regions near the doubly magic nuclei 78Ni (Z=28 and N=50) and 132Sn (Z=50 and N=82). For this purpose we have developed specialized methods and instrumentation to measure various observables. There is also the opportunity to perform precision experiments with stable beams using exactly the same state-of-the-art instrumentation and techniques as with their radioactive ion beam counterpart. I describe some of the recent efforts at HRIBF to do more precise measurements using particle-gamma techniques.
Macroscopic quasi-dc currents produced in gases ionized by intense two-color laser fields are known as an efficient source of highly intense broadband terahertz pulses. Recent experimental and theoretical studies give conflicting results regarding the optimal phase shift between the components of a two-color field to maximize the terahertz energy. To address these contradictions, we are studying the role of the effect of the Coulomb potential on the escaping electron in the formation of the ionization-induced directional photocurrents in a two-color scheme. We demonstrate that due to the Coulomb effects, the optimal phase shift between the fundamental field and its second harmonic strongly depends on the laser intensity. In a wide range of laser intensities, the Coulomb effects are shown to significantly influence the directional current generation. (paper)
We propose to exploit the unique capability of ISOLDE to provide intense post-accelerated $^{144}$Ba ion beams from the REX facility to enable the Coulomb excitation of the first 3$^{-}$ state in this nucleus. By measuring the $\\gamma$-ray yields of the E1 decay connecting the 3$^{-}$ and 2$^{+}$ states using the MINIBALL array, we can obtain the interesting transition matrix element. The result will give quantitative information about octupole correlations in this nucleus. We require 27 shifts to fulfill the aims of the experiment.
Double beta decays of 100Mo by ELEGANT V at Oto Cosmo Observatory
Exclusive measurements of neutrino-less double beta decays(0νββ) of 100Mo were made by means of ELEGANT V. The present status of the double beta decay experiment with ELEGANT V is presented. The data at Oto lab., being combined with the data at Kamioka, gives stringent limits on half-lives for 0νββ and < 1.7 eV
Research on the scattering cross sections for positive ions excited by high energy electron impact has been watched with keen interest in recent years. The reason may be the requirements of data on these cross-sections for investigating solar corona and plasma phenomena, and the difference existing between different approximations. Normally, Coulomb-Born approximation has been used, in which analyses are carried out using the Coulomb type wave function as electron scattering waves. However, it has been made clear that the results were very small as compared with that of Born approximation, i.e. the problem seems to remain that at very high energy, whether the cross sections in both approximations differ or not, and the difference, if exist, is large or small. This paper shows that the scattering cross sections for excited C4+, N5+, O6+ and Ne8+ ions were determined for transitions 1s21S→1s2p 1P, 1s21S→1s3p 1P, 1s2s 3S→1s2p 3P, 1s2s 3S→1s3p 3P, and 1s2p 3P→1s3s 3S. The results indicate that these values in Born approximation agree well with the values obtained in Coulomb-Born approximation for incident energy about 12 times or more of the threshold energy except the transition of 1s2s 3S→1s2p 3P. (Wakatsuki, Y.)
A non-partial-wave Coulomb-Born theory is recently formulated to treat the excitation of many-electron atomic ions for impact by an arbitrary charged particle [Y.B. Duan et al. (1997)]. The multiple expansion of the transition matrix element is decomposed into the target form factor and the projectile form factor. These are the matrix elements of the tensor operators between quantum states so that any complicated wave function for the target ion can be employed. In this formal theory, an infinitesimally small positive quantity ε is introduced artificially to guarantee the convergence of integrals. As a supplementary part of the theory, we discuss how to choose the value of ε. It is found that the ε should be taken as functions of the momentum transfer vertical stroke q vertical stroke = vertical stroke ki-kf vertical stroke and multipolarity λ. Illustrations are carried out by calculating the cross-sections for some typical transitions nala-nblb of hydrogen-like ions for impact by electron, positron, and proton, respectively. The resulting cross-sections are in good agreement with ones produced by using a method available for ion targets with Slater-type orbitals [N.C. Deb, N.C. Sil (1993)]. Comparisons demonstrate that the Coulomb-Born theory with non-partial wave analysis provides a powerful method to treat the excitation of many-electron atomic ions impact by an arbitrary charged particle. (orig.)
Butler, P; Cederkall, J A; Reiter, P; Wiens, A; Blazhev, A A; Kruecken, R; Voulot, D; Kalkuehler, M; Wadsworth, R; Gernhaeuser, R A; Hess, H E; Holler, A; Finke, F; Leske, J; Huyse, M L; Seidlitz, M
We propose to study the properties of neutron-rich nuclei $^{28,29,30}$Na via Coulomb excitation experiments using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Reliable B(E2,0$^{+}$ $\\rightarrow$ 2$^{+}$) values for $^{30,32}$Mg were obtained at ISOLDE. Together with recent new results on $^{31}$Mg, collective and single particle properties are probed for Z=12 at the N=20 neutron closed shell, the 'island of inversion'. We would like to extend this knowledge to the neighbouring $^{28,29,30}$Na isotopes where a different transition from the usual filling of the neutron levels into the region with low lying 2p-2h cross shell configurations is predicted by theory. Detailed theoretical predictions on the transition strength in all three Na nuclei are awaiting experimental verification and are the subject of this proposal. At REX beam energies of 3.0 MeV /nucleon the cross-sections for Coulomb excitation are sufficient. Moreover the results from the close-by $^{30,31,32}$Mg nuclei de...
Butler, P; Bastin, B; Kruecken, R; Voulot, D; Rahkila, P J; Orr, N A; Srebrny, J; Grahn, T; Clement, E; Paul, E S; Gernhaeuser, R A; Dorsival, A; Diriken, J V J; Huyse, M L; Iwanicki, J S
The neutron-deficient polonium isotopes with two protons outside the closed Z=82 shell represent a set of nuclei with a rich spectrum of nucleus structure phenomena. While the onset of the deformation in the light Po isotopes is well established experimentally, questions remain concerning the sign of deformation and the magnitude of the mixing between different configurations. Furthermore, controversy is present with respect to the transition from the vibrational-like character of the heavier Po isotopes to the shape coexistence mode observed in the lighter Po isotopes. We propose to study this transition in the even-mass neutron-deficient $^{198,200,202}$Po isotopes by using post-accelerated beams from REX-ISOLDE and "safe"-energy Coulomb excitation. $\\gamma$- rays will be detected by the MINIBALL array. The measurements of the Coulomb excitation differential cross section will allow us to deduce both the transition and diagonal matrix elements for these nuclei and, combined with lifetime measurements, the s...
Guichard, R
2007-12-15
We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when {Dirac_h}{omega} > I{sub p}: it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with {Dirac_h}{omega} < I{sub p}: new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)
99Mo Production via 100Mo(n,2n)99Mo using accelerator neutrons
Nagai Yasuki
2014-01-01
A new production method of 99Mo using accelerator neutrons via the 100Mo(n,2n)99Mo reaction was proposed. Intense neutrons with a most probable energy of 14 MeV can be produced by bombarding Be or C with 40 MeV deuteron beams. Research and development works of 99Mo produced by neutrons from the 3H(d,n)4He reaction were carried out. High quality 99mTc was obtained by employing a sublimation method. Accelerator neutrons are shown to have a great potential to produce a wide variety of radioisoto...
99Mo production by 100Mo(n,2n)99Mo using accelerator neutrons
We proposed a new route to produce a medical radioisotope 99Mo by the 100Mo(n,2n)99Mo reaction using accelerator neutrons. A high-quality 99Mo with a minimum level of radioactive waste can be obtained by the proposed reaction. The decay product of 99Mo, 99mTc, is separated from 99Mo by the sublimation method. The proposed route could bring a major breakthrough in the solution of ensuring a constant and reliable supply of 99Mo. (author)
Enriched Zn$^{100}$MoO$_4$ scintillating bolometers to search for $0 \
Barabash, A S; Danevich, F A; Giuliani, A; Ivanov, I M; Makarov, E P; Mancuso, M; Marnieros, S; Nasonov, S G; Nones, C; Olivieri, E; Pessina, G; Poda, D V; Shlegel, V N; Tenconi, M; Tretyak, V I; Vasiliev, Ya V; Velazquez, M; Zhdankov, V N
2014-01-01
The LUMINEU project aims at performing a demonstrator underground experiment searching for the neutrinoless double beta decay of the isotope $^{100}$Mo embedded in zinc molybdate (ZnMoO$_4$) scintillating bolometers. In this context, a zinc molybdate crystal boule enriched in $^{100}$Mo to 99.5\\% with a mass of 171 g was grown for the first time by the low-thermal-gradient Czochralski technique. The production cycle provided a high yield (the crystal boule mass was 84\\% of initial charge) and an acceptable level -- around 4\\% -- of irrecoverable losses of the costy enriched material. Two crystals of 59 g and 63 g, obtained from the enriched boule, were tested aboveground at milli-Kelvin temperature as scintillating bolometers. They showed a high detection performance, equivalent to that of previously developed natural ZnMoO$_4$ detectors. These results pave the way to future sensitive searches based on the LUMINEU technology, capable to approach and explore the inverted hierarchy region of the neutrino mass p...
Butler, P; Voulot, D; Rahkila, P J; Darby, I G; Grahn, T; Bree, N C F; Julin, R J; Diriken, J V J; Jenkins, D G; Kroell, T; Huyse, M L
In regions near magic nuclei, seniority can be regarded as a good quantum number. In the N = 122 isotones above the Z = 82 shell closure relative high-$\\textit{j}\\,$ single-particle proton orbitals dominate the structure and thus levels up to $\\textit{I}$ = 2$\\textit{j}$ - 1 could, in principle, be understood within the seniority scheme. While B(E2) values usually increase within the band with increasing $\\textit{I}$, the seniority scheme can lead to a contrasting result. The present proposal addresses this phenomenon through the measurements of previously unknown B(E2; 0$^{+}\\rightarrow$ 2$^{+}$) values in $^{206}$Po and $^{208}$Rn. The proposed Coulomb excitation measurements of radioactive beams will be carried out at the REX-ISOLDE facility using the MINIBALL $\\gamma$-ray spectrometer.
Barloutaud, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1958-06-15
The following nuclei were excited by protons of 5 MeV maximum energy: {sup 182}W - {sup 184}W - {sup 186}W - {sup 186}Os - {sup 188}Os - {sup 189}Os - {sup 190}Os - {sup 192}Os - {sup 194}Pt - {sup 196}Pt - {sup 198}Pt - {sup 198}Hg - {sup 200}Hg - {sup 202}Hg - {sup 204}Hg - {sup 206}Pb. The reduced probabilities of the various transitions were deduced from the coulomb excitation cross-section measurements. For some even-even nuclei two 2 + levels were excited. The properties of the excited levels are interpreted in terms of the collective model. (author) [French] Au moyen de protons d'energie inferieure a 5 MeV, l'excitation coulombienne des noyaux suivants a ete etudiee: {sup 182}W - {sup 184}W - {sup 186}W - {sup 186}Os - {sup 188}Os - {sup 189}Os - {sup 190}Os - {sup 192}Os - {sup 194}Pt - {sup 196}Pt - {sup 198}Pt - {sup 198}Hg - {sup 200}Hg - {sup 202}Hg - {sup 204}Hg - {sup 206}Pb. La mesure de la section efficace d'excitation coulombienne a permis de deduire les -probabilites reduites des diverses transitions observees. Dans certains noyaux pair-pair, deux niveaux de caractere 2 + ont ete excites. L'interpretation de ces niveaux en termes de niveaux de rotation et de niveaux de vibration a l'aide du modele collectif est discutee. En particulier, la variation des proprietes de ces niveaux avec la deformation nucleaire permet de fixer des limites a la validite des diverses hypotheses entrant dans le modele collectif. (auteur)
Gomes, L.C.; Horodynski-Matsushigue, L.B.; Borello-Lewin, T.; Duarte, J.L.; Hirata, J.H.; Salem-Vasconcelos, S.; Dietzsch, O. [Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05389-970 Sao Paulo, SP (Brazil)
1996-11-01
Coulomb-nuclear interference data for incident energies between 9 and 17 MeV were obtained in the form of elastic and inelastic (to the 2{sup +}{sub 1} states) excitation functions of backscattered ({theta}{approx_equal}172.8{degree}) alpha particles on {sup 100,102,104}Ru. The analysis was done in a distorted-wave Born approximation within a deformed optical model approach. {ital B}({ital E}2) values, obtained from the charge deformation lengths {delta}{sup {ital C}} extracted from the low energy data, are compatible for the three isotopes within {approximately} 2{sigma} with published values. The nuclear quadrupolar deformation lengths {delta}{sup {ital N}}, obtained from the analysis of the interference region of the excitation functions, and also of one angular distribution at 22 MeV measured for {sup 100}Ru are generally lower than the corresponding charge deformation lengths, the difference increasing with increasing {ital A} of the isotope, {delta}{sup {ital N}} being 18{percent} lower than {delta}{sup {ital C}} for {sup 104}Ru (2{sup +}{sub 1}). Nuclear deformation lengths associated with the 3{sub 1}{sup {minus}} states of {sup 100,102,104}Ru and with the 4{sup +}{sub 2} state of {sup 100}Ru at 2.367 MeV were also obtained as a by-product of the present work. {copyright} {ital 1996 The American Physical Society.}
Low-energy Coulomb excitation of {sup 62}Fe and {sup 62}Mn following in-beam decay of {sup 62}Mn
Gaffney, L.P.; Bree, N.; Witte, H. de; Huyse, M.; Duppen, P. van [KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); Walle, J.V. de [KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); CERN-ISOLDE, CERN, Geneva (Switzerland); Bastin, B. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); GANIL CEA/DSM-CNRS/IN2P3, Caen (France); Bildstein, V.; Wimmer, K. [Technische Universitaet Muenchen, Physics Department E12, Garching (Germany); Blazhev, A.; Fransen, C.; Gernhaeuser, R.; Hess, H.; Reiter, P.; Seidlitz, M.; Warr, N. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Cederkaell, J.; DiJulio, D. [University of Lund, Physics Department, Lund (Sweden); Darby, I. [University of Jyvaskyla, Department of Physics, Jyvaskyla (Finland); Diriken, J.; Kesteloot, N. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); Belgian Nuclear Research Centre SCK-CEN, Mol (Belgium); Fedosseev, V.N.; Gustafsson, A.; Marsh, B.A.; Voulot, D.; Wenander, F. [CERN-ISOLDE, CERN, Geneva (Switzerland); Kroell, T. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Lutter, R. [Ludwig-Maximilians-Universitaet-Muenchen, Muenchen (Germany); Wrzosek-Lipska, K. [KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven (Belgium); University of Warsaw, Heavy Ion Laboratory, Warsaw (Poland)
2015-10-15
Sub-barrier Coulomb excitation was performed on a mixed beam of {sup 62}Mn and {sup 62}Fe, following in-trap β{sup -} decay of {sup 62}Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418 keV, which has been tentatively associated to a (2{sup +},3{sup +}) → 1{sub g.s.}{sup +} transition. This fixes the relative positions of the β-decaying 4{sup +} and 1{sup +} states in {sup 62}Mn for the first time. Population of the 2{sub 1}{sup +} state was observed in {sup 62}Fe and the cross-section determined by normalisation to the {sup 109}Ag target excitation, confirming the B(E2) value measured in recoil-distance lifetime experiments. (orig.)
Excitation Functions of Fusion and Fission for 32S+170Er at Energies Near and Below Coulomb Barrier
BAO; Peng-fei; LIN; Cheng-jian; YANG; Feng; JIA; Hui-ming; XU; Xin-xing; YANG; Lei; SUN; Li-jie; MA; Nan-ru; ZHANG; Huan-qiao; LIU; Zu-hua
2013-01-01
Excitation functions of fusion evaporation residue(ER)and fission for 32S+170Er system at near barrier energy region were measured,respectively.With the comparison to the calculations of coupledchannels effects,it is accessible to investigate the impacts on the fusion and fission processes of target deformation and the dependence on the entrance-channel.The experiment was performed at Beijing HI-13 Tandem Accelerator.Fission and fusion evaporation
The AMoRE (Advanced Mo based Rare process Experiment) Collaboration is planning to employ 40Ca100MoO4 single crystals as a cryogenic Scintillation detector for studying the neutrinoless double-beta decay of the isotope 100Mo. A simultaneous readout of phonon and scintillation signals is performed in order to suppress the intrinsic background. The planned sensitivity of the experiment that would employ 100 kg of 40Ca100MoO4 over five years of data accumulation would be T1/20ν = 3 × 1026 yr, which corresponds to values of the effective Majorana neutrino mass in the range of 〈mν〉 ∼ 0.02–0.06 eV
At the fission product separator JOSEF a superconducting magnet was installed which permits the determination of the g factors of excited levels of fission products. In the framework of this thesis the g factors of the 21+ levels of the neutron-rich isotopes 102Mo and 104Mo were measured. It resulted g = 0.42±0.07 for 102Mo and g = 0.19 -0.10+0.12 for 104Mo. These values were compared with other g factors of neighbouring nuclei in order to obtain from this a statement about the g factors of the proton respectively neutron bosons gπ and gν derived in the IBA model. Furthermore from the measured g factors for the 100Zr an effective proton boson number of Nπ = 1.4±0.7 was calculated which means that the subshell closure at the Z=40 is further valid for N=60. In the second part of the thesis the decay of the 100Nb and the level scheme of the 100Mo was studied. From B9 distribution, β half-lives, and γ-γ coincidence measurements the term scheme of the 100Mo could be established from the high spin decay of the 100Nb. By the study of the β feedings a spin of the high spin isomer Iπ = 4+ could be concluded. This isomer can by shell model considerations be interpreted as πg9/2 x νs1/2 configuration. In γ-γ angular correlations further excited 0+ levels in the 100Mo were detected. Furthermore δ mixing parameters for two 2-2 transitions could be given with δ = 4.4 -0.9+1.5 for 21+-22+ and δ = 0.27±0.12 for 23+-21+. According to the vibrational model by means of the obtained data an assignment of some levels to the single phonon excitations was performed. Indeed the low lying 02+ state is not compatible with the vibrational model. The IBA model explains this state as head of an additional band with contrary configuration mixing of Nπ = 1 respectively Nπ = 3 in comparison with the ground state. (orig.)
Bekker, T B; Danevich, F A; Degoda, V Ya; Giuliani, A; Grigorieva, V D; Ivannikova, N V; Mancuso, M; de Marcillac, P; Moroz, I M; Nones, C; Olivieri, E; Pessina, G; Poda, D V; Shlegel, V N; Tretyak, V I; Velazquez, M
2014-01-01
Large lithium molybdate (Li$_2$MoO$_4$) crystal boules were produced by using the low thermal gradient Czochralski growth technique from deeply purified molybdenum. A small sample from one of the boules was preliminary characterized in terms of X-ray-induced and thermally-excited luminescence. A large cylindrical crystalline element (with a size of $\\oslash 40\\times40$ mm) was used to fabricate a scintillating bolometer, which was operated aboveground at $\\sim 15$ mK by using a pulse-tube cryostat housing a high-power dilution refrigerator. The excellent detector performance in terms of energy resolution and $\\alpha$ background suppression along with preliminary positive indications on the radiopurity of this material show the potentiality of Li$_2$MoO$_4$ scintillating bolometers for low-counting experiment to search for neutrinoless double beta decay of $^{100}$Mo.
2002-01-01
We propose to perform Coulomb excitation experiments of neutron-rich nuclei in the vicinity of $^{68}$Ni towards $^{78}$Ni using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Major changes in the structure of the atomic nucleus are expected around the N = 40 subshell closure. Recent B(E2) measurements suggested that $^{68}$Ni behaves like a doubly magic nucleus while neutron-rich Zn isotopes with N>38 exhibit a sudden increase of B(E2) values which may be the signature of deformation. We would like to check and test these predictions for neutron-rich nuclei in the vicinity of N = 40 and N = 50 shell closures like $^{72}$Zn, $^{74}$Zn, $^{76}$Zn, $^{68}$Ni, $^{70}$Ni. Our calculations show that an energy upgrade from 2.2 to 3 MeV/nucleon will be of crucial importance for a part of our study while some nuclei can still be very efficiently studied at an energy of 2.2 MeV/nucleon. Therefore, to perform our experiment in an efficient way, we request 21 shifts of beam time before the ene...
Shell structure in the vicinity of the doubly magic {sup 100}Sn via Coulomb excitation at PreSPEC
Guastalla, Giulia
2014-11-17
The PreSPEC setup in combination with the high intensity primary beams available at GSI provided unique opportunities for the key nuclear structure studies on exotic nuclei. The experiment performed on the neutron deficient {sup 104}Sn aimed to deduce the reduced transition probability of the first excited 2{sup +} state quantified by the B(E2; 0{sup +} → 2{sup +}) value. This result is the central point in the discussion of the evolution of nuclear structure in proximity of the doubly magic nucleus {sup 100}Sn. As {sup 100}Sn is not yet accessible for such measurements, a series of experiments have been performed for neutron-deficient Sn isotopes over the past few years. These data showed excessive experimental B(E2) strength compared to shell model calculations below neutron number N=64 and they are therefore not excluding a constant or even increasing collectivity below {sup 106}Sn. Hence, the measurement of the B(E2) value in the next even-even isotope toward {sup 100}Sn, i.e. {sup 104}Sn, was a crucial step to verify the robustness of the shell gap of {sup 100}Sn. Moreover, {sup 104}Sn is the heaviest isotope of the Sn isotopic chain for which a shell model calculation without significant truncation of the valence space can be performed and therefore with this experimental value the validity of Large Scale Shell Model (LSSM) calculations could be tested. As a main result of the experiment a B(E2) value corresponding to 0.10(4) e{sup 2}b{sup 2} has been extracted for {sup 104}Sn. The experimental value showed a very good agreement with the predicted one and, despite the large error bar, it clearly established a downward trend of the B(E2) values of the Sn isotopic chain toward A=100. This implied enhanced stability of the N = Z = 50 shell closure against ph-excited quadrupole modes. However, an experiment of this kind is very challenging for several reasons. First, {sup 104}Sn lies in proximity of the proton drip line and has therefore a small production
Development of CaMoO4 crystal scintillators for double beta decay experiment with 100-Mo
Annenkov, A.N.; Buzanov, O. A.; Danevich, F. A.; Georgadze, A. Sh.; Kim, S K; Kim, H. J.; Kim, Y.D.(Center for Underground Physics, Institute for Basic Science (IBS), Daejon, 305-811, Korea); Kobychev, V. V.; Kornoukhov, V.N.; Korzhik, M.; Lee, J. I.; Missevitch, O; Mokina, V. M.; S. S. Nagorny(INR Kiev); Nikolaiko, A. S.
2007-01-01
Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma rays and alpha particles, temperature dependence of scintillation properties, and radioactive contamination were studied with CaMoO4 crystal scintillators. A high sensitivity experiment to search for neutrinoless double beta decay of 100-Mo by using CaMoO4 scintillators is discussed.
The paper demonstrates the possibility of separating 98Mo and 100Mo isotopes by means of the electromagnetic separator in the system of axially symmetric magnetic fields with two field reversals. The advantage of the method lies in the separation of the 100M o isotope in its pure form, without being contaminated with other isotopes. Of apparent interest is the proposed here method of increasing the productive capacity of the electromagnetic technique of isotope separation.
Binary-reaction spectroscopy of 99,100Mo: Intruder alignment systematics in N=57 and N=58 isotones
The near-yrast states of 99,100Mo have been studied following their population via a binary reaction between a 136Xe beam and a thin, self-supporting 100Mo target. The yrast sequence in 100Mo has been extended to a tentative spin/parity (20 + ) , while the decoupled band built on the I π =(11/2) - isomeric state in 99Mo has been extended through the first alignment up to a tentative spin/parity of ((43/2) - ) . The results are compared with self-consistent, cranked-mean-field calculations using a Woods-Saxon potential. The alignment systematics of the intruder h 11/2 bands in the N=57 isotones from Mo (Z=42) to Cd (Z=48) and the yrast sequences in their N=58 even-even neighbors are discussed. An overall picture emerges, where the alignment properties evolve from being due to positive-parity neutrons in the 48105Cd to predominantly (g 9/2 ) 2 proton crossings closer to the Z=40 subshell. Qualitatively, this can be explained by an increase in the quadrupole deformation and a simultaneous lowering of the proton Fermi surface in the g 9/2 shell with decreasing proton number. These data provide excellent examples of rotational-alignment phenomena in weakly deformed nuclei
Coulomb Potentials between Spherical and Deformed Nuclei
ZHANG Gao-Long; LE Xiao-Yun; LIU Zu-Hua
2008-01-01
@@ Coulomb potentials for spherical-deformed reaction partners are calculated in terms of the double folding model as well as the conventional formulas. Our results show that the Coulomb potentials calculated with different approaches have quite different behaviours in the internal region of the potential. Because fusion process is sensitive to the barrier height and the internal part of the potential, the fusion excitation function, especially the fusion barrier distribution, should provide a strict test of the interaction potentiaLs. Therefore, we calculate the fusion excitation function and barrier distribution for the 16O+154 Sm system with different versions of the Coulomb potentials, in comparison with the experimental results. It is found that the fusion excitation function and barrier distribution of 16 O+154 Sm are obviously different for the different versions of the Coulomb potentials.By means of this comparison, we may conclude that the double folding model with the accurate approximate form can provide rather reasonable Coulomb potentials.
Physico-chemical processes following the chemisorption of sulfur on (100)Mo, that is: growth of the surface and volume sulfides, their thermo-stability, variation of emission and catalytic properties of the surface are studied using high resolution (δ E/E ≤ 0.1%) EOS with recording of spectra directly from the specimen highly heated up to T = 2000 K. The work of yield and bound energy of sulfur atom depending on the level of Mo surface population by S atoms are determined. It is shown that Mo exposure in H2S atmosphere under T = 300-2000 K does not result in accumulation of S atoms within the specimen volume. The absolute concentration of sulfur atoms in the surface sulfide is determined and it is shown that its stoichiometry is MoS. 31 refs., 5 figs
Preparation of 99Mo from the 100Mo(γ,n) reaction and chemical separation of 99mTc
The radionuclide 99Mo has been prepared by 100Mo(γ, n) reaction using two types of natural molybdenum compound (molybdenum trioxide and zirconium molybdate gel) with the bremsstrahlung end-point energies of 10 and 15 MeV. After the equilibrium, 99mTc was separated as NaTcO4 from the irradiated samples using two different chemical procedures to examine the chemical yield. The separated Na[99mTc]TcO4 from the ZrMo gel has the 99Mo breakthrough of <10-4 %, radiochemical purity >99 % as well as chemical impurities of Al, Mo and Zr < 10 ppm. The estimation of 99Mo and 99mTc was done by using off-line c-ray spectrometric technique. The chemical yield of the separated 99mTc from the dissolved molybdenum trioxide is 70.7-75.2 %, whereas in the undissolved zirconium molybdate gel, it is 19.1-43 %. The second method is preferable because it is user friendly in hospital radiopharmacy throughout the shelf-life. (author)
On the modelling of Coulomb friction
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.
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
High resolution experiments performed during the past few years demonstrated that the various reaction modes occurring in heavy ion collisions can strongly influence each other. This interrelation of the different reaction modes brings a nuclear structure dependence to the fusion and deep-inelastic channels that were previously described in the framework of pure statistical models. In order to fully understand the interrelation between these reaction channels, a complete set of measurements including elastic and inelastic scattering, few-nucleon transfer and fusion is required. In continuation of our earlier measurements of the fusion cross sections in the system {sup 58,64}Ni + {sup 92,100}Mo we finished the studies of the quasielastic process in these systems. The experiments were done in inverse reaction kinematics using the split-pole spectrograph with its hybrid focal-plane detector for particle identification. The experiments with {sup 100}Mo beams were performed previously. First test runs with {sup 92}Mo showed the possible interference with {sup 98}Mo ions which could be eliminated by using the 13{sup +} charge state from the ECR source. The data from these experiments were completely analyzed. The smallest transfer cross sections are observed for the systems {sup 64}Ni + {sup 100}Mo and {sup 58}Ni + {sup 92}Mo, i.e., the most neutron-rich and neutron-deficient systems, respectively. For the other systems, {sup 64}Ni + {sup 92}Mo and {sup 58}Ni + {sup 100}Mo, the transfer cross sections at energies close to the barrier are about of equal magnitude. This observation does not correlate with the deviation of the experimental fusion cross sections from the coupled-channels predictions. While for {sup 58}Ni + {sup 100}Mo discrepancies between the experimental and theoretical fusion cross sections are observed, the system {sup 64}Ni + {sup 92}Mo which shows about the same transfer yields, is quite well described by the coupled-channels calculations.
Bauer, Christopher; Pietralla, Norbert; Bloch, Timo; Boenig, Sabine; Kroell, Thorsten; Leske, Joerg; Scheck, Marcus; Stahl, Christian; Stegmann, Robert [IKP, TU Darmstadt (Germany); Rainovski, Georgi; Damyanova, Antoaneta; Danchev, Miroslav; Gladnishki, Kalin [University of Sofia (Bulgaria); Blazhev, Andrey; Moschner, Kevin [IKP, Universitaet zu Koeln (Germany); Pakarinen, Janne [CERN, Geneva (Switzerland); Werner, Volker [WNSL, Yale University, New Haven, CT (United States)
2012-07-01
A radioactive beam of {sup 140}Nd was impinging on a 1.40 mg/cm{sup 2} {sup 48}Ti as well as a 1.55mg/cm{sup 2} {sup 64}Zn target. Gamma rays were detected by the MINIBALL array and a DSSD was used for particle identification. The transition strength of the first 2{sup +} state to the 0{sup +} ground state of neutron-deficient {sup 140}Nd was measured to be 30(5) W.u. This result deviates from empirical rules for quadrupole collectivity and microscopic predictions. This unexpected behavior prompts for new, refined microscopic calculations and might be related to the shell stabilization of the quadrupole isovector valence shell excitations. The result is important for the planned experiment at HIE-ISOLDE, which aims to identify the one-phonon mixed-symmetry 2{sup +} state of {sup 140}Nd.
Coulomb dissociation of N,2120
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.
Arnold, R; Baker, J; Barabash, A S; Brudanin, V; Caffrey, A J; Caurier, E; Egorov, V; Errahmane, K; Etienvre, A I; Guyonnet, J L; Hubert, F; Hubert, P; Jollet, C; Jullian, S; King, S; Kochetov, O; Konovalov, S; Kovalenko, V; Lalanne, D; Leccia, F; Longuemare, C; Lutter, G; Marquet, C; Mauger, F; Nowacki, F; Ohsumi, H; Piquemal, F; Reyss, J L; Saakyan, R; Sarazin, X; Shitov, Yu; Simard, L; Simkovic, F; Smolnikov, A A; Stekl, I; Suhonen, J; Sutton, C S; Szklarz, G; Thomas, J; Timkin, V; Tretyak, V; Umatov, V; Vàla, L; Vanyushin, I A; Vasilyev, V; Vorobel, V; Vylov, T
2006-01-01
The NEMO-3 tracking detector is located in the Fr\\'ejus Underground Laboratory. It was designed to study double beta decay in a number of different isotopes. Presented here are the experimental half-life limits on the double beta decay process for the isotopes $^{100}$Mo and $^{82}$Se for different Majoron emission modes and limits on the effective neutrino-Majoron coupling constants. In particular, new limits on "ordinary" Majoron (spectral index 1) decay of $^{100}$Mo ($T_{1/2} > 2.7\\cdot10^{22}$ y) and $^{82}$Se ($T_{1/2} > 1.5\\cdot10^{22}$ y) have been obtained. Corresponding bounds on the Majoron-neutrino coupling constant are $\\langle g_{ee} \\rangle < (0.4-1.9) \\cdot 10^{-4}$ and $< (0.66-1.7) \\cdot 10^{-4}$.
Accelerator-based production of 99Mo. A comparison between the 100Mo(p,x) and 96Zr(α,n) reactions
Innovative accelerator-based production routes for 99Mo (and 99mTc) have been studied, comparing the 100Mo(p,x)99Mo,99mTc and 96Zr(α,n)99Mo reactions, for which a new set of measurement has been made. Theoretical and experimental cross sections have been analysed and used to calculate 99Mo production yields and specific activity (SA), considering fully enriched and commercially available target materials. Results show that the low SA resulting from the p-based route forces the use of alternative generator systems, while the α-based reaction provides very high SA 99Mo but much lower yield. Benefits and drawbacks of direct 99mTc production via the 100Mo(p,2p) reaction are also discussed. (author)
Shaginyan, V. R.
2002-01-01
The density functional determining the Coulomb energy of nuclei is calculated to the first order in $e^2$. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CC...
Thompson, Richard C
2014-01-01
Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.
Chernyak, D M; Dumoulin, L; Giuliani, A; Mancuso, M; de Marcillac, P; Marnieros, S; Nones, C; Olivieri, E; Poda, D V; Tretyak, V I
2016-01-01
Random coincidences of nuclear events can be one of the main background sources in low-temperature calorimetric experiments looking for neutrinoless double-beta decay, especially in those searches based on scintillating bolometers embedding the promising double-beta candidate $^{100}$Mo, because of the relatively short half-life of the two-neutrino double-beta decay of this nucleus. We show in this work that randomly coinciding events of the two-neutrino double decay of $^{100}$Mo in enriched Li$_2$$^{100}$MoO$_4$ detectors can be effectively discriminated by pulse-shape analysis in the light channel if the scintillating bolometer is provided with a Neganov-Luke light detector, which can improve the signal-to-noise ratio by a large factor, assumed here at the level of $\\sim 750$ on the basis of preliminary experimental results obtained with these devices. The achieved pile-up rejection efficiency results in a very low contribution, of the order of $\\sim 6\\times10^{-5}$ counts/(keV$\\cdot$kg$\\cdot$y), to the ba...
Danevich, F. A.; Bergé, L.; Boiko, R. S.; Chapellier, M.; Chernyak, D. M.; Coron, N.; Devoyon, L.; Drillien, A.-A.; Dumoulin, L.; Enss, C.; Fleischmann, A.; Gastaldo, L.; Giuliani, A.; Gray, D.; Gros, M.; Hervé, S.; Humbert, V.; Ivanov, I. M.; Juillard, A.; Kobychev, V. V.; Koskas, F.; Loidl, M.; Magnier, P.; Makarov, E. P.; Mancuso, M.; de Marcillac, P.; Marnieros, S.; Marrache-Kikuchi, C.; Navick, X.-F.; Nones, C.; Olivieri, E.; Paul, B.; Penichot, Y.; Pessina, G.; Plantevin, O.; Poda, D. V.; Redon, T.; Rodrigues, M.; Shlegel, V. N.; Strazzer, O.; Tenconi, M.; Torres, L.; Tretyak, V. I.; Vasiliev, Ya. V.; Velazquez, M.; Viraphong, O.
2015-10-01
The LUMTNEU program aims at performing a pilot experiment on 0ν2β decay of 100Mo using radiopure ZnMoO4 crystals enriched in 100Mo operated as cryogenic scintillating bolometers. Large volume ZnMoO4 crystal scintillators (˜ 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and α/β particle discrimination capability. Zinc molybdate crystal scintillators enriched in 100Mo were grown for the first time by the low-thermal-gradient Czochralski technique with a high crystal yield and an acceptable level of enriched molybdenum irrecoverable losses. A background level of ˜ 0.5 counts/(yr keV ton) in the region of interest can be reached in a large detector array thanks to the excellent detectors radiopurity and particle discrimination capability, suppression of randomly coinciding events by pulse-shape analysis, and anticoincidence cut. These results pave the way to future sensitive searches based on the LUMTNEU technology, capable of approachingand exploring the inverted hierarchy region of the neutrino mass pattern.
The LUMTNEU program aims at performing a pilot experiment on 0ν2β decay of 100Mo using radiopure ZnMoO4 crystals enriched in 100Mo operated as cryogenic scintillating bolometers. Large volume ZnMoO4 crystal scintillators (∼ 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and α/β particle discrimination capability. Zinc molybdate crystal scintillators enriched in 100Mo were grown for the first time by the low-thermal-gradient Czochralski technique with a high crystal yield and an acceptable level of enriched molybdenum irrecoverable losses. A background level of ∼ 0.5 counts/(yr keV ton) in the region of interest can be reached in a large detector array thanks to the excellent detectors radiopurity and particle discrimination capability, suppression of randomly coinciding events by pulse-shape analysis, and anticoincidence cut. These results pave the way to future sensitive searches based on the LUMTNEU technology, capable of approachingand exploring the inverted hierarchy region of the neutrino mass pattern
Danevich, F. A., E-mail: danevich@kinr.kiev.ua; Boiko, R. S.; Chernyak, D. M.; Kobychev, V. V. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine); Bergé, L.; Chapellier, M.; Drillien, A.-A.; Dumoulin, L.; Humbert, V.; Marcillac, P. de; Marnieros, S.; Marrache-Kikuchi, C.; Olivieri, E.; Plantevin, O.; Tenconi, M. [Centre de Sciences Nucléaires et de Sciences de la Matière, CNRS/IN2P3, Université Paris-Sud, 91405 Orsay (France); Coron, N.; Redon, T.; Torres, L. [IAS, CNRS, Université Paris-Sud, 91405 Orsay (France); Devoyon, L.; Koskas, F. [CEA, Centre d’Etudes Saclay, Orphée, 91191 Gif-Sur-Yvette Cedex (France); and others
2015-10-28
The LUMTNEU program aims at performing a pilot experiment on 0ν2β decay of {sup 100}Mo using radiopure ZnMoO{sub 4} crystals enriched in {sup 100}Mo operated as cryogenic scintillating bolometers. Large volume ZnMoO{sub 4} crystal scintillators (∼ 0.3 kg) were developed and tested showing high performance in terms of radiopurity, energy resolution and α/β particle discrimination capability. Zinc molybdate crystal scintillators enriched in {sup 100}Mo were grown for the first time by the low-thermal-gradient Czochralski technique with a high crystal yield and an acceptable level of enriched molybdenum irrecoverable losses. A background level of ∼ 0.5 counts/(yr keV ton) in the region of interest can be reached in a large detector array thanks to the excellent detectors radiopurity and particle discrimination capability, suppression of randomly coinciding events by pulse-shape analysis, and anticoincidence cut. These results pave the way to future sensitive searches based on the LUMTNEU technology, capable of approachingand exploring the inverted hierarchy region of the neutrino mass pattern.
Chernyak, Dmitry
2015-01-01
ZnMoO$_4$ scintillators with a mass of $\\sim$ 0.3 kg, as well as Zn$^{100}$MoO$_4$ crystals enriched in the isotope $^{100}$Mo were produced for the first time by using the low-thermal-gradient Czochralski technique. The optical and luminescent properties of the produced crystals were studied to estimate the progress in crystal growth quality. The low-temperature tests with a 313 g ZnMoO$_4$ and two enriched Zn$^{100}$MoO$_4$ crystals were performed aboveground in the Centre de Sciences Nucl\\'eaires et de Sciences de la Mati\\`ere. The low background measurements with a three ZnMoO$_4$ and two enriched detectors installed in the EDELWEISS set-up at the Laboratoire Souterrain de Modane were carried out. To optimize the light collection in ZnMoO$_4$ scintillating bolometers, we have simulated the collection of scintillation photons in a detector module for different geometries by Monte Carlo method using the GEANT4 package. Response to the 2$\
16O Coulomb decomposition project '93
The adaptability of magnetic analyzers in Japan to this research project was compared and investigated, and the Coulomb decomposition process and the experimental conditions for 16O were examined. By the measurement of the delayed-α spectrum in 16N decay, a new restriction was set to the E1 reaction rate of 12C(α, γ)16O reaction. Hereafter, the research on the E2 reaction rate is urgently needed. There is large expectation for the Coulomb decomposition reaction of 16O as the probe especially sensitive to the E2 reaction rate of the important reaction for celestial body physics. At the meeting held on July 30, the RIKEN SMART spectrometer (F2) was judged as optimal, and its merits are explained. Also a demerit is pointed out. The ion optic parameters of the SMART F2 are shown. In the meeting held on December 17, investigation was carried out on α-12C coincidence count rate and projectile fragmentation background, Coulomb decomposition process and focal plane detector. The reaction cross section of Coulomb E2 excitation was evaluated by Monte Carlo method. As to the possibility of applying Coulomb decomposition process under the circumstance that nuclear force and Coulomb force compete, the new direction was indicated. The experimental plan is shown. (K.I.)
Aytekin, Hüseyin; Yılmaz, Alaaddin
2015-06-01
We calculated the half-lives of two-neutrino double beta decay (2ν β β ) of 76Ge, 82Se, 96Zr and 100Mo nuclei for the 0+ ↦ 0+ transition. Quasiparticle random phase approximation (QRPA) was used by considering the charge-exchange spin-spin interactions among the nucleons by considering both particle-hole (p-h) and particle-particle (p-p) channels in the separable form. Calculations were performed for the spherical form of the nuclei.
The density functional determining the Coulomb energy of nuclei is calculated to the first order in e2. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CCE is shown to come from the surface region of nuclei. The CCE effect on the calculated proton drip line is examined, and the maximum charge Z of nuclei near this line is found to decrease by 2 or 3 units. The effect of Coulomb interaction on the effective proton mass is analyzed
Shaginyan, V R
2001-01-01
The density functional determining the Coulomb energy of nuclei is calculated to the first order in $e^2$. It is shown that the Coulomb energy includes three terms: the Hartree energy; the Fock energy; and the correlation Coulomb energy (CCE), which contributes considerably to the surface energy, the mass difference between mirror nuclei, and the single-particle spectrum. A CCE-based mechanism of a systematic shift of the single-particle spectrum is proposed. A dominant contribution to the CCE is shown to come from the surface region of nuclei. The CCE effect on the calculated proton drip line is examined, and the maximum charge $Z$ of nuclei near this line is found to decrease by 2 or 3 units. The effect of Coulomb interaction on the effective proton mass is analyzed.
Greensite, J.; Olejnik, S.
2003-09-26
We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.
We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.
Tse, Wang-Kong; Hu, Ben Yu-Kuang; Sarma, S. Das
2007-01-01
We study the Coulomb drag between two single graphene sheets in intrinsic and extrinsic graphene systems with no interlayer tunneling. The general expression for the nonlinear susceptibility appropriate for single-layer graphene systems is derived using the diagrammatic perturbation theory, and the corresponding exact zero-temperature expression is obtained analytically. We find that, despite the existence of a non-zero conductivity in an intrinsic graphene layer, the Coulomb drag between int...
99m Tc (T1/2 = 6 h) in various chemical forms is the most commonly used radiotracer in nuclear medicine, covering more than 70% of all nuclear medical diagnosis due to its multiple advantages. It decays with a suitable half-life and emits a 140.5 keV γ-ray, which is ideally suited for imaging via single photon emission computed tomography (SPECT) and causes minimal radiation dose to the patient. It is popular due to its convenient availability through a 99Mo/99mTc generator system and its capability to form a wide variety of complexes with organic ligands, which can be obtained instantaneously as kit formulations. The parent radionuclide 99Mo (T1/2=66 h) is generally produced via neutron-induced fission of highly enriched 235U in a nuclear reactor. Two reactors, NRU Canada and HFR Nether lands, which together meet about 70% of the world demand of 99Mo. Owing to various problems from these suppliers, an alternative method for the production of 99Mo and 99mTc is suggested using the proton induced reaction of highly enriched 100Mo target. Further, there are large discrepancies in published reaction cross section data for 100Mo(p,2n) 99mTc reaction
The underlying structure in the region A ∼ 100, N ∼ 60 has been under intensive and extensive investigation, mainly by β-decay and γ-ray spectroscopy from fission processes. Around N ∼ 60, by adding just few neutrons, protons a rapid shape change occurs from spherical-like to well deformed g.s. shape. Shape coexistence has been observed in the Sr and Zr nuclei, and is expected to take place in the whole region. The mechanisms involved in the appearance of the deformation is not well understood. The interplay between down-sloping and up-sloping neutron Nilsson orbital is evoked as one of the main reasons for the sudden shape change. However, a clear identification of the active proton and neutron orbitals was still on-going. For that purpose, the neutron rich 93;95;97;99Rb isotopes have been studied by Coulomb excitation at CERN (ISOLDE) using the REX-ISOLDE post-accelerator and the MINIBALL setup. The completely unknown structures of 97;99Rb have been populated and observed. Prompt γ-ray coincidences of low-lying states have been observed and time-correlated in order to build level schemes. The associated transition strengths have been extracted with the GOSIA code. The observed matrix elements of the electromagnetic operator constituted new inputs of further theoretical calculations giving new insight on the involved orbitals. The sensitivity of such experiment can be increased using nuclear spin polarized radioactive ion beam. For that purpose the Tilted Foils Technique (TFT) of polarization has been investigated at CERN. This technique consists to spin polarize the ion beam, passing through thin foils tilted at an oblique angle with respect to the beam direction. The initially obtained atomic polarization is transferred to the nucleus by hyperfine interaction. This technique does not depend on the chemical nature of the element. Short lived nuclei can be polarized in-flight without any need to be stopped in a catcher. It opens up the possibility to post
Characteristics of Coulomb fission
Oberacker, Volker; Greiner, Walter; Kruse, Hans; Pinkston, William T.
2006-01-01
Within an extended semiquantal theory we perform large-sized coupled-channel calculations involving 260 collective levels for Coulomb fission of 238U. Differential Coulomb fission cross sections are studied as a function of bombarding energy and impact parameter for several projectiles. In the Xe + U case, total cross sections are also given. We find a strong dependence on projectile charge number, PCF(180°)∼(Zp)6 in the region 50≤Zp≤92 for a fixed ratio E/ECoul, which might...
On Coulomb disintegration of relativistic nuclei and hypernuclei
The dependence of the total cross-section of excitation and disintegration of a relativistic nucleus in the Coulomb field on the energy and parameters characterizing nuclear dimensions is investigated. The analogy with the problem of atomic ionization at the passage of charged particles through matter is used. The results are applied to the description of the Coulomb dissociation of nuclei with small binding energies. An explicit expression for the effective cross-section of the Coulomb disintegration of the hypernucleus-Λ3H into a deuteron and Λ-particle. 12 refs
Dynamical features of Coulomb-fission
Fission following quasielastic scattering was investigated in the reactions 208Pb -> 238U below the Coulomb Barrier and 7.5 MeV/u 238U -> 238U at scattering angles forward of the grazing angle (870). A kinematically complete analysis of 3-body coincidences was carried out measuring position and time-of-flight of the scattered projectile-like particle and 2 fission fragments in large parallel plate detectors. In the reaction 208Pb -> 238U, measured at backward angles, the slope of the differential cross section at 5.4 MeV/u is in qualitative agreement with the theoretical expectation for Coulomb-fission. The angular distribution of the fission fragments, measured with respect to the semisector axis (apex line towards the projectile), is close to 1/sinTHETA and does not show any of the significant structures predicted by several theories. The anisotropy is smaller in all other coordinate systems investigated. The fission probability in the reaction 238U -> 238U, measured down to 5x10-4 at THETAsub(cm)=540 (corresponding to 75% Esub(cb) at the distance of closest approach) as well as the low excitation energy 0 as expected for Coulomb-fission. The absence of a detectable final state Coulomb interaction yields a lower limit of 1-2x10-20s for the lifetime of the fissioning nucleus. (orig./HSI)
Holographic Coulomb branch vevs
Skenderis, K; Skenderis, Kostas; Taylor, Marika
2006-01-01
We compute holographically the vevs of all chiral primary operators for supergravity solutions corresponding to the Coulomb branch of N=4 SYM and find exact agreement with the corresponding field theory computation. Using the dictionary between 10d geometries and field theory developed to extract these vevs, we propose a gravity dual of a half supersymmetric deformation of N=4 SYM by certain irrelevant operators.
Hwang, E. H.; Sarma, S. Das
2011-01-01
We calculate theoretically the Coulomb drag resistivity for two graphene monolayers spatially separated by a distance "$d$". We show that the frictional drag induced by inter-layer electron-electron interaction goes asymptotically as $T^2/n^3$ and $T^2 \\ln(n)/n$ in the high-density ($k_F d \\gg 1$) and low-density ($k_F d \\ll 1$) limits, respectively.
Coulomb dissociation of $^{20,21}$N
Röder, Marko; 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; Caamano, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkall, Joakim; Chakraborty, S; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Pramanik, Ushasi Datta; 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; Diaz, Diego Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Bleis, Tudi Le; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Caro, Magdalena Mostazo; 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; Saez, Jose Sanchez del Rio; 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
2016-01-01
Neutron-rich light nuclei and their reactions play an important role for the creation of chemical elements. Here, data from a Coulomb dissociation experiment on $^{20,21}$N are reported. Relativistic $^{20,21}$N 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 $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ and $^{20}\\mathrm{N}(\\mathrm{n},\\gamma)^{21}\\mathrm{N}$ excitation functions and thermonuclear reaction rates have been determined. The $^{19}\\mathrm{N}(\\mathrm{n},\\gamma)^{20}\\mathrm{N}$ 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.
Double beta decay without neutrino emission provides a test of the mass and nature of neutrinos (Majorana or Dirac). Experimental proof would be the observation of a peak at the transition energy in the spectrum of the two emitted electrons. The expected half-life of the process is extremely long (about 1025 years for 100Mo). So, being thus, it is very important to get a good knowledge of the origins and contributions of background noise in the region where the signal could occur. The main origins of the background noise in the region where the signal could occur. The main origins of the background noise are found to be e+ - e- pairs induced by heavy energy gamma rays. These gamma rays follow the thermal neutron capture by the components of the detector. Another factor in the production of background noise is natural radio-activity. For example, the presence of Radon in the laboratory has been observed to produce deposits of 214Bi on the sides of the detector. Data taken with the NEMO 2 prototype and an enriched molybdenum source foil indicates that the background limit reached is of the order of 1 event per year in the 3 MeV region. Results of this work have proven the necessity to have a magnetic field in NEMO 3 in order to reject e+ - e-pairs. (author)
Electron-positron pair production in strong Coulomb fields is outlined. It is shown that the singular behaviour of the adiabatic basis can be removed if solutions of the time dependent external field Dirac equation are used as a basis to expand the fermion field operator. This latter 'asymptotic basis' makes it possible to introduce Feynman-propagator. Applying the reduction technique, the computation of all of the basic quantities can be reduced to the solution of an integral equation. The positron spectrum for separable potential model with Lorentzian time dependence and for potential jump is analyzed in the pole approximation. (author)
Heavy ion reactions around the Coulomb barrier
无
2011-01-01
The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The ex perimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O+208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface re gion. The breakup cross section and the coupling between breakup and elastic scattering are small.
Strong impact of protonation and deprotonation on intermolecular Coulombic decay
Intermolecular Coulombic decay (ICD) is an ultrafast relaxation mechanism of a highly excited system embedded in a chemical environment. Our theoretical investigation of ammonia clusters shows that the ICD efficiency can be regulated by protonation or deprotonation. It is suggested that by varying ICD rate through changing the environmental pH value a control over the relaxation dynamics can be achieved.
Coulomb dissociation in nonrelativistic and relativistic collisions
Electromagnetic excitations in the Coulomb field of nuclei have been studied using quantum as well as semiclassical methods. Even at relatively modest incident energies, the Coulomb dissociation cross sections of projectiles with relatively low particle thresholds could be of sizeable order of magnitude. Such a study complements our knowledge about radiative capture processes, which are of interest for nuclear astrophysics. Quite a few questions remain to be answered, like the importance of nuclear interactions for small angle scattering, interference of different multipolarities for triple differentiial cross sections and distortion effects on the three-body final states. In the case of dissociation at relativistic energies it is shown that only for the total cross section both semiclassical and quantim-mechanical methods yield the same results. As an example the Primakoff effect is considered, where in an M1 excitation of ≅ 80 MeV a Λ hyperion is converted into a Σo hyperion by means of the virtual photon field of heavy target nuclei. Virtual photon spectra for all multipolarities can be calculated. This provides a sound basis for the analysis of electromagnetic dissociation experiments at relativistic heavy ion accelerators, like the BEVALAC. 10 figs., 25 refs
Coulomb chronometry to probe the decay mechanism of hot nuclei
Gruyer, Diego; Bonnet, E; Chbihi, A; Ademard, G; Boisjoli, M; Borderie, B; Bougault, R; Galichet, E; Gauthier, J; Guinet, D; Lautesse, Philippe; Neindre, N Le; Legouée, E; Lopez, O; Marini, P; Mazurek, K; Nadtochy, P N; Pârlog, M; Rivet, M F; Roy, R; Rosato, E; Spadaccini, G; Verde, G; Vient, E; Vigilante, M; Wileczko, J -P
2013-01-01
In $^129$Xe+$^{nat}$Sn central collisions from 12 to 25 MeV/A, 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 unambiguously 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 break-ups decreases with increasing bombarding energy, becoming quasi-simultaneous above excitation energy $E^*=4.0\\pm0.5$ MeV/A.
Coulomb interactions within halo EFT
Preliminary results of an effective field theory applied to nuclear cluster systems are presented, where Coulomb interactions play a significant role. Presented at the 20th Few-Body Conference, Pisa, Italy, 10-14 September 2007. (author)
Long-range Coulomb interaction in nodal-ring semimetals
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.
Sharma, M K; Prasad, R; Gupta, S; Musthafa, M M; Bhardwaj, H D; Sinha, A K
2003-01-01
In order to study complete and incomplete fusion in heavy ion induced reactions the experiment has been carried out for measuring excitation functions (EF's) for several reactions in the system sup 1 sup 2 C + sup 1 sup 2 sup 8 Te, in the energy range approx = 42 - 82 MeV, using activation technique. To the best of our knowledge EF's for presently measured reactions are being reported for the first time. The measured EF's have been compared with those calculated theoretically using codes CASCADE and ALICE-91. Effect of variation of parameters, of the codes, on calculated EF's has also been studied. The analysis of the present data indicates presence of contributions from incomplete fusion in some cases. In general, theoretical calculations agree well with the experimental data.
Coulomb dissociation of light unstable nuclei
Kido, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Yabana, Kazuhiro; Suzuki, Yoshiyuki
1997-05-01
The aim of this study is that a simulation method applicable to the atomic nucleus with neutron halo structure developed till now is applied to a wider range unstable nucleus containing proton excess nucleus to also attribute understanding of nuclear reaction with interest in astronomical nuclear reaction. The proton dissociation energy in {sup 8}B nucleus is small value of 138 eV, which is thought to have a structure of proton at the most outer shell bound much weakly by core nucleus and spread in thinner thickness. For the coulomb excitation of such weak bound system, quantum theoretical and non-perturbational treatment is important. Therefore, 3-dimensional time-dependent Schroedinger equation on relative wave function of the core nucleus {sup 7}Be and halo proton p will be dissolved in time space and will execute a time developmental simulation. (G.K.)
Coulomb explosion of "hot spot"
Oreshkin, V I; Chaikovsky, S A; Artyomov, A P
2016-01-01
The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed and estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.
Coulomb interactions in particle beams
This book develops analytical and computer models for beams in which Coulomb interactions are important. The research into the different phenomena of Coulomb interactions in particle beams is stimulated by developments in the field of electron beam lithography for VLSI electronics. The standard theory of charged particle optics breaks down for intense beams in which interactions between particles are significant. This monograph is devoted to the theory of these intense beams, which are not only used in VLSI electronics but also in scanning electron microscopes. The theory is also applicable to focused ion beams, which are used in VLSI mask repair
Renormalization in Coulomb gauge QCD
Research highlights: → The Hamiltonian in the Coulomb gauge of QCD contains a non-linear Christ-Lee term. → We investigate the UV divergences from higher order graphs. → We find that they cannot be absorbed by renormalization of the Christ-Lee term. - Abstract: 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.
Entropic Corrections to Coulomb's Law
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.
Coulombic Fluids Bulk and Interfaces
Freyland, Werner
2011-01-01
Ionic liquids have attracted considerable interest in recent years. In this book the bulk and interfacial physico-chemical characteristics of various fluid systems dominated by Coulomb interactions are treated which includes molten salts, ionic liquids as well as metal-molten salt mixtures and expanded fluid metals. Of particular interest is the comparison of the different systems. Topics in the bulk phase concern the microscopic structure, the phase behaviour and critical phenomena, and the metal-nonmetal transition. Interfacial phenomena include wetting transitions, electrowetting, surface freezing, and the electrified ionic liquid/ electrode interface. With regard to the latter 2D and 3D electrochemical phase formation of metals and semi-conductors on the nanometer scale is described for a number of selected examples. The basic concepts and various experimental methods are introduced making the book suitable for both graduate students and researchers interested in Coulombic fluids.
Laser-induced nuclear excitation
An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 103 Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.
Coulomb interactions in Ga LMIS
Radlička, Tomáš; Lencová, Bohumila
2008-01-01
Roč. 108, č. 5 (2008), s. 445-454. ISSN 0304-3991 Grant ostatní: EC 5RP(XE) G5RD-CT-2000-00344 Institutional research plan: CEZ:AV0Z20650511 Source of funding: R - rámcový projekt EK Keywords : liquid-metal ion sources * Coulomb interactions * energy width * virtual source size Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.629, year: 2008
Fusion excitation functions involving transitional nuclei
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.
Computational Analysis of Intermolecular Coulombic Decay Effects in DNA nucleotide Photoionization
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.
Coulomb excitation of Ca-44 and Ar-46
Calinescu, S.; Caceres, L.; Grévy, S.; Sorlin, O.; Dombradi, Z.; Stanoiu, M.; Astabatyan, R.; Borcea, C.; Borcea, R.; Bowry, M.; Catford, W.; Clement, E.; Franchoo, S.; Garcia, R.; Gillibert, R.; Guerin, I. H.; Kuti, I.; Lukyanov, S.; Lepailleur, A.; Maslov, V.; Morfouace, P.; Mrázek, Jaromír; Negoita, F.; Niikura, M.; Perrot, L.; Podolyak, Z.; Petrone, C.; Penionzhkevich, Y. E.; Roger, T.; Rotaru, F.; Sohler, D.; Stefan, I.; Thomas, J. C.; Vajta, Zs.; Wilson, E.
2016-01-01
Roč. 93, č. 4 (2016), s. 044333. ISSN 0556-2813 Institutional support: RVO:61389005 Keywords : neutron rich nuclei * low lying states * scattering Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.733, year: 2014
Structure of light neutron-rich nuclei through Coulomb dissociation
U Datta Pramanik; T Aumann; D Cortina; H Emling; H Geissel; M Hellström; R Holzmann; N Iwasa; Y Leifels; G Münzenberg; M Rejmund; C Scheidenberger; K Sümmerer; A Leistenschneider; Th W Elze; A Grünschloss; S Ilievski; K Boretzky; J V Kratz; R Kulessa; E Lubkiewicz; E Wajda; W Walus; P Reiter; H Simon
2001-08-01
Coulomb breakup of neutron-rich nuclei around mass ∼ 20 has been studied experimentally using secondary beams (∼ 500–600 MeV/u) of unstable nuclei produced at GSI. The spectroscopic factor deduced for the neutron occupying 1/2 level in 15C ground state is consistent with the earlier reported value. The data analysis for Coulomb breakup of 17C shows that most of the cross section yields the 16C core in its excited state. For 17-22O, the low-lying E1 strength amounts up to about 12% of the energy weighted dipole sum rule strength depending on neutron excess. The cluster sum rule limit with 16O as a core is almost exhausted for 17,18O, while for more neutron rich isotopes the strength with respect to that limit decreases.
Suitability of linear quadrupole ion traps for large Coulomb crystals
Tabor, D A; Odom, B
2011-01-01
Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial component of micromotion, which leads to first-order Doppler shifts along the preferred spectroscopy axis in precision measurements on large Coulomb crystals. Finally, we compare trapping potential anharmonicity, which can induce nonlinear resonance heating by shifting normal mode frequencies onto resonance as a crystal grows. We apply a non-deforming crystal approximation for simple calculation of these anharmonicity-induced shifts, allowing a straightforward estimation of when crystal growth can lead to excitation of diff...
Attractive Coulomb interaction of two-dimensional Rydberg excitons
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.
Coulomb disintegration as an information source for relevant processes in nuclear astrophysics
The possibility of obtaining the photodisintegration cross section using the equivalent-photon number method first deduced and employed for the Coulomb disintegration processes has been suggested. This is very interesting because there exist radioactive capture processes, related to the photodisintegration through time reversal, that are relevant in astrophysics. In this paper, the recent results of the Karlsruhe and the Texas A and M groups on the Coulomb disintegration of 6Li and 7Li and the problems of the method are discussed. The ideas developed in a previous paper (Nucl. Phys. A458 (1986) 188) are confirmed qualitatively. To understand the process quantitatively it is necessary to use a quantum treatment that would imply the introduction of Coulomb excitation effects of higher orders. The Coulomb disintegration of exotic secondary beams is also studied. It is particularly interesting the question about what kind of nuclear structure information, as binding energies of momentum distributions, may be obtained. (Author)
PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems
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
Coulomb-Blockade Oscillations in Semiconductor Nanostructures
Houten, van, H.; Beenakker, C. W. J.; Staring, A.A.M.
2005-01-01
I. Introduction (Preface, Basic properties of semiconductor nanostructures). II. Theory of Coulomb-blockade oscillations (Periodicity of the oscillations, Amplitude and lineshape). III. Experiments on Coulomb-blockade oscillations (Quantum dots, Disordered quantum wires, Relation to earlier work on disordered quantum wires). IV. Quantum Hall effect regime (The Aharonov-Bohm effect in a quantum dot, Coulomb blockade of the Aharonov-Bohm effect, Experiments on quantum dots, Experiments on disor...
Coulomb dissociation of 8B and solar neutrino problem
We measured the cross section for Coulomb dissociation of 8B using a radioactive 8B beam of 46.5MeV/u energy with a 208Pb target. The cross section for the 7Be(p,γ)8B capture reaction was deduced at Ecm=0.6-1.7MeV. The extracted astrophysical S17 factors were consistent with the values measured by Vaughn et al. and Filippone et al. Possible corrections due to 7Be excited state population, E1 and M2 contribution, nuclear contribution and post acceleration effects are considered. ((orig.))
Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages
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.
Charge-carrier dynamics and Coulomb effects in semiconductor tetrapods
charge carriers were additionally studied at high excitation energies. An efficient multi-exciton emission of the CdSe/CdS tetrapods could be observed, which is to be lead back to the exciton phase-space filling and a reduced Auger effect. The larger volume of the longer tetrapods allows a dual emission from the CdSe and the CdS with comparable intensities. The occuring Coulomb effects between a spatially separated electron-hole pair were studied in CdSe/CdTe tetrapods, which exhibit a type-II transition. A correlation between the tetrapod leg length and the binding energy of the charge-transfer exciton could be established, which is also reproduced in the theoretical simulations.
PREFACE: Strongly Coupled Coulomb Systems
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
Coulomb correction calculations of pp Bremsstrahlung
The effects of the Coulomb interaction upon the photon cross section and analyzing power from pp Bremsstrahlung have been studied in detail. Off-shell properties of the Coulomb T matrices have been considered but the associated, Coulomb modified, hadronic T matrices are important elements in any analyses of low energy, forward proton scattering data. At the lowest energy considered (5 MeV), the full calculations gave cross sections that were half the size of those found without Coulomb effects or with a simple model approximation to them. With increasing energy, the cross sections varied to those characteristic of magnetic interaction dominance and the specific differences due to Coulomb effects diminished. 47 refs., 7 figs
The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.
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)
Ion-induced molecular fragmentation: beyond the Coulomb explosion picture
The fragmentation of the CO molecule by O7+ ion impact is investigated in two different energy regimes by fragment ion momentum spectroscopy. The improved resolution of the present kinetic energy release measurement together with application of a time-dependent wave packet dynamics method used in conjunction with new high-level computations of a large number of dication potential energy curves enables one to unambiguously assign each line to an excited state of the transient molecular dication produced during the collision. This is the first direct experimental evidence of the limitations of the Coulomb explosion model to reproduce the molecular fragmentation dynamics induced by ion impact. Electron removal due to a capture process is shown to transfer less excitation to the target than direct ionization. At low collision velocity, the three-body interaction between the projectile and the two fragments is also clearly highlighted. (author). Letter-to-the-editor
Highlights: • The energy spectra for composite particle emissions are calculated by the nuclear models. • The double differential cross-sections for composite particle emitted are calculated. • The improved Iwamoto-Harada model for composite particles emitted is accommodated. • The Pauli principle in the calculation of exciton state densities is accommodated. • The calculated results agree well with experimental data. - Abstract: The energy spectra and double-differential cross sections of neutron, proton, deuteron, triton, helium and alpha-particle emitted are studied by the exciton model including the improved Iwamoto–Harada model. All cross sections, angular distributions, energy spectra and double-differential cross sections are consistently calculated and analyzed for p+92,94,95,96,97,98,100Mo reactions at the incident proton energies below 200 MeV by using nuclear theoretical models which integrate the optical model, the intra-nuclear cascade model, direct, pre-equilibrium and equilibrium reaction theories. The theoretically calculated results are compared with existing experimental data
Havermeier, 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; 10.1103/PhysRevLett.104.133401
2010-01-01
Using synchrotron radiation we simultaneously ionize and excite one helium atom of a helium dimer (He_2) 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.
Properties of Parabolic Linear Bound Potential and Coulomb Bound Potential Quantum Dot Qubit
REN Ji-Rong; WANG Zi-Wu; ZHU Tao; LI Wei-Ping; DUAN Yi-Shi; YIN Ji-Wen; XIAO Jing-Lin
2008-01-01
On the condition of electric-LO phonon strong-coupling in a parabolic quantum dot, we obtain the eigenen-ergy of the ground-state and the first-excited state, the eigenfunctions of the ground-state and the first- excited state by using variational method of Pekar type. This system in quantum dot may be employed as a two-level quantum system-qubit. When the electron is in the superposition state of the ground- and the first-excited state, we obtain the time evolution of the electron density. The relation of the probability density of electron on the Coulomb binding parameter and the relations of the period of oscillation on the Coulomb binding parameter, the electron-LO-phonon coupling constant and the confinement length are derived.
Coulomb continuum effects in molecular interference
We study analytically the interference in photoionization of molecules by monochromatic and attosecond x-ray pulses. Using the hydrogen molecule ion as a test case, we obtain simple analytical factors describing the Coulomb continuum molecular interference. We show how chirped attosecond pulse with a frequency-dependent phase and broad bandwidth creates the continuous photoelectron spectra. Due to the long-range Coulomb forces, the plane wave interference patterns are strongly modified by two-centre Coulomb continuum even at large internuclear distances. (letter to the editor)
Coulomb Friction Driving Brownian Motors
We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced. (general)
Quarks in Coulomb gauge perturbation theory
Popovici, C; Reinhardt, H
2008-01-01
Coulomb gauge quantum chromodynamics within the first order functional formalism is considered. The quark contributions to the Dyson-Schwinger equations are derived and one-loop perturbative results for the two-point functions are presented.
Numerical path integration with Coulomb potential
Myrheim, Jan
2003-01-01
A simple and efficient method for quantum Monte Carlo simulation is presented, based on discretization of the action in the path integral, and a Gaussian averaging of the potential, which works well e.g. with the Coulomb potential.
Aspects of Confinement in Coulomb Gauge
Greensite, Jeff
2009-01-01
I present some new results regarding confinement as it appears in Coulomb gauge. It is found that: i) a recently proposed Yang-Mills vacuum wavefunctional in temporal gauge and 2+1 dimensions yields a Coulomb-gauge ghost propagator and linear Coulomb potential in good agreement with lattice Monte Carlo results; ii) adding a few constituent gluons to heavy quark-antiquark states brings the interaction energy much closer to that of the static quark potential, and suggests the beginnings of gluon-chain formation at roughly one fermi; iii) a perturbative approach to Faddeev-Popov eigenvalues indicates that the zero eigenvalue at the Gribov horizon may occur either at, or away from, p=0, depending on the gauge choice and spacetime dimension. This last result may be relevant to the qualitatively different infrared behavior of the ghost propagator in Coulomb and Landau gauges.
Coulomb Interaction Does Not Spread Instantaneously
Tzontchev, R I; Rivera-Juarez, J M
2000-01-01
The experiment is described which shows that Coulomb interaction spreads with a limit velocity and thus this kind of interaction cannot be considered as so called "instantaneous action at a distance".
Coulomb dissociation at nonrelativistic and relativistic energies
The author studies the breakup of deuterons on nuclei in the framework of DWBA theories which are based on the spectator model. The discrepancies for heavy targets are explained by the mechanism of the Coulomb dissociation. (HSI)
Comments on Coulomb pairing in aromatic hydrocarbons
Huber, D L
2013-01-01
Recently reported anomalies in the double-photonionization spectra of aromatic molecules such as benzene, naphthalene, anthracene and coronene are attributed to Coulomb-pair resonances of pi electrons.
Cavity QED experiments with ion Coulomb crystals
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan; Albert, Magnus; Drewsen, Michael
Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained.......Cavity QED experimental results demonstrating collective strong coupling between ensembles of atomic ions cooled into Coulomb crystals and optical cavity fields have been achieved. Collective Zeeman coherence times of milliseconds have furthermore been obtained....
Coulomb interactions in particle beams
This thesis presents a theoretical description of the Coulomb interaction between identical charged particles (electrons or ions) in focussed beam. The charge-density effects as well as the various statistical interaction effects, known as the Boersch effect and the 'trajectory displacement effect', are treated. An introductory literature survey is presented from which the large differences in theoretical approach appear. Subsequently the methods are investigated which are used in studies of comparable problems in plasma physics and stellar dynamics. These turn out to be applicable to particle beams only for certain extreme conditions. The approach finally chosen in this study is twofold. On the one hand use is made of a semi-analytical model in which the statistical and dynamical aspects of the N-particle problem are reduced to two-particle problem. This model results in a number of explicit equations in the experimental parameters, with ties of the beam can be determined directly. On the other hand use has been made of a purely numerical Monte Carlo model in which the kinematical equations of an ensemble interacting particles with 'at random' chosen starting conditions are solved exactly. This model does not lead to general expressions, but yields a specific numerical prediction for each simulated experimental situation. The results of both models appear to agree well mutually. This yields a consistent theory which complements the existing knowledge of particle optics and which allow the description of systems in which the interaction between particles can not be neglected. The predictions of this theory are qualitatively and quantitatively compared with those from some other models, recently reported in literature. (author). 256 refs.; 114 figs.; 1180 schemes; 5 tabs
Yang-Mills theory in Coulomb gauge
In this thesis we study the Yang-Mills vacuum structure by using the functional Schroedinger picture in Coulomb gauge. In particular we discuss the scenario of colour confinement, which was originally formulated by Gribov. After a short introduction, we recall some basic aspects of Yang-Mills theories, its canonical quantization in the Weyl gauge and the functional Schroedinger picture. We then consider the minimal Coulomb gauge and the Gribov problem of the gauge theory. The gauge fixing of the Coulomb gauge is done by using the Faddeev-Popov method, which enables the resolution of the Gauss law - the constraint on physical states. In the third chapter, we variationally solve the stationary Yang-Mills Schroedinger equation in Coulomb gauge for the vacuum state. Therefor we use a vacuum wave functional, which is strongly peaked at the Gribov horizon. The vacuum energy functional is calculated and minimized resulting in a set of coupled Schwinger-Dyson equations for the gluon energy, the ghost and Coulomb form factors and the curvature in gauge orbit space. Using the angular approximation these integral equations have been solved analytically in both the infrared and the ultraviolet regime. The asymptotic analytic solutions in the infrared and ultraviolet regime are reasonably well reproduced by the full numerical solutions of the coupled Schwinger-Dyson equations. In the fourth chapter, we investigate the dependence of the Yang-Mills wave functional in Coulomb gauge on the Faddeev-Popov determinant. (orig.)
Inelastic scattering and nucleon transfer in the system 232Th+206Pb at the Coulomb barrier
By the experiment performed in the present thesis on the example of the system 232Th+206Pb the onset of the nuclear interaction in the region of the Coulomb barrier was studied at an incident energy of 6.3 MeV/nucleon. In the range of distances of closest approximation 15.5 fm ≤ D ≤ 38.7 fm respectively 28deg ≤ ΘCM ≤ 150deg the Coulomb excitation of the target isotope was observed. The strong absorption for 'small' distances from the reaction channel of the Coulomb excitation is confirmed by the occurrence of transfer reactions. In the studied thorium-lead system the transfer of one and two neutrons could be detected by means of the characteristic γ radiation of the isotopes 230Th and 207,208Pb with a cross section of 500 mb summed over the measurement range. The possibilities of an evaporation of neutrons from highly excited target nuclei, which could also lead to the isotope 230Th and by this influence the measurement of the 2n transfer, was also studied. The contribution of these processes to the transfer could be estimated to less than 5%. For the determination of the excitation energy, at which the transfer takes place, the transfer probabilities experimentally determined as functions of the distance of closest approximation were compared with the barrier-penetration model originally developed for sub-Coulomb transfer. Small effective neutron-binding energies of 0.6-0.8 MeV and by this high excitation energies resulted in contradiction to our model-independent measurement by means of the mean γ multiplicity and mean γ energies. (orig./HSI)
Creation of planar charged fermions in Coulomb and Aharonov-Bohm potentials
Khalilov, V.R. [Moscow State University, Faculty of Physics, Moscow (Russian Federation)
2013-08-15
The creation of charged fermions from the vacuum by a Coulomb field in the presence of an Aharonov-Bohm (AB) potential are studied in 2+1 dimensions. The process is governed by a (singular) Dirac Hamiltonian that requires the supplementary definition in order for it to be treated as a self-adjoint quantum-mechanical operator. By constructing a one-parameter self-adjoint extension of the Dirac Hamiltonian, specified by boundary conditions, we describe the (virtual bound) quasistationary states with ''complex energy'' emerging in an attractive Coulomb potential, derive for the first time, complex equations (depending upon the electron spin and the extension parameter) for the quasistationary state ''complex energy''. The constructed self-adjoint Dirac Hamiltonians in Coulomb and AB potentials are applied to provide a correct description to the low-energy electron excitations, as well as the creation of charged quasiparticles from the vacuum in graphene by the Coulomb impurity in the presence of AB potential. It is shown that the strong Coulomb field can create charged fermions for some range of the extension parameter. (orig.)
Coulomb displacement energies in nuclei
In the present work the positions of the isobaric analog resonances (IAR) are calculated using the HF-TDA theory with a complete proton particle-neutron hole basis. The important feature of this approach is the fact that the HF potential and the particle-hole interaction used in the TDA are derived from the same two-body interactions. In this theroy all the higher order effects are taken into account in one consistent framework. The calculations are performed for several N > Z, closed shell nuclei. For these nuclei good agreement between the experimental and theoretical excitation energies of the IAR is obtained. (orig.)
Recoil ions from molecular targets: sequential Coulomb explosions
Fast ion collision processes appear to be ideal for producing multiply charged molecular ions. The advantage of this technique has not been appreciated so far and very little work has been carried out so far. We have initiated a programme to study the formation of multiply charged molecular ions and their dissociation dynamics using fast ion beam from the pelletron. Measurements have been carried out on several molecules including N2, CO, CO2, CS2, CH4 and CH3I. Measurements of the kinetic energy distributions of the fragment ions provided novel results on the fragmentation of CS2 and CO2 ions. As expected the positive ions of S and O possessed very large kinetic energies resulting from the Coulomb explosion of highly charged molecular ions. The surprising result was that the positive ions (C+ and C2+) from the central carbon atom of the linear symmetric molecules possessed much larger energies that what is expected from the conventional physical picture of Coulomb explosion. It is concluded that the observed high kinetic energy C+ and C2+ ions are formed by sequential fragmentation of CO2n+ ions through an intermediate K-shell excited CO+* ions. (author). 4 refs., 1 fig
Calculation of nuclear excitation in an electron transition
Pisk, K. (Institut Rudjer Boskovic, Zagreb (Yugoslavia)); Kaliman, Z. (Rijeka Univ. (Yugoslavia). Faculty of Pedagogics); Logan, B.A. (Ottawa Univ., ON (Canada). Ottawa-Carleton Centre for Physics)
1989-11-06
We have made a theoretical investigation of nuclear excitation during an electron transition (NEET). Our approach allows us to express the NEET probabilities in terms of the excited nuclear level width, the energy difference between the nuclear and electron transition, the Coulomb interaction between the initial electron states, and the electron level width. A comparison is made with the available experimental results. (orig.).
Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals
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.
Thermoelectric properties of Coulomb-blockaded fractional quantum Hall islands
Lachezar S. Georgiev
2015-05-01
Full Text Available We show that it is possible and rather efficient to compute at non-zero temperature the thermoelectric characteristics of Coulomb blockaded fractional quantum Hall islands, formed by two quantum point contacts inside of a Fabry–Pérot interferometer, using the conformal field theory partition functions for the chiral edge excitations. The oscillations of the thermopower with the variation of the gate voltage as well as the corresponding figure-of-merit and power factors, provide finer spectroscopic tools which are sensitive to the neutral multiplicities in the partition functions and could be used to distinguish experimentally between different universality classes sharing the same electric properties. We also propose a procedure for measuring the ratio r=vn/vc of the Fermi velocities of the neutral and charged edge modes for filling factor νH=5/2 from the power-factor data in the low-temperature limit.
Interatomic Coulombic decay widths of helium trimer: Ab initio calculations
Kolorenč, Přemysl, E-mail: kolorenc@mbox.troja.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Institute of Theoretical Physics, V Holešovičkách 2, 180 00 Prague (Czech Republic); Sisourat, Nicolas [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France)
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.
Study of Ground State Wave-function of the Neutron-rich 29,30Na Isotopes through Coulomb Breakup
Rahaman A.
2014-03-01
Full Text Available Coulomb breakup of unstable neutron rich nuclei 29,30Na around the ‘island of inversion’ has been studied at energy around 434 MeV/nucleon and 409 MeV/nucleon respectively. Four momentum vectors of fragments, decay neutron from excited projectile and γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence. For these nuclei, the low-lying dipole strength above one neutron threshold can be explained by direct breakup model. The analysis for Coulomb breakup of 29,30Na shows that large amount of the cross section yields the 28Na, 29Na core in ground state. The predominant ground-state configuration of 29,30Na is found to be 28Na(g.s⊗νs1/2 and 29Na(g.s⊗νs1/2,respectively.
Coulomb nuclear interference with deuterons in even palladium isotopes
Angular distributions for the inelastic scattering of 13.0 MeV deuterons on 104,106,108,110Pd were measured with the Sao Paulo Pelletron-Enge-Spectrograph facility in the range of 120 ≤θlab ≤640. A Coulomb-Nuclear Interference analysis, employing the Distorted Wave Born Approximation with the Deformed Optical Model as transition potential, under well established global optical parameters, was applied to the first quadrupolar excitations. The values of C = δLC/δLN, the ratio of charge to isoscalar deformation lengths, and of (δLN)2 were extracted through the comparison of experimental and predicted cross section angular distributions. The ratios of reduced charge to isoscalar transition probabilities, B(EL) to B(ISL) respectively, are related to the square of the parameter C and were thus obtained with the advantage of scale uncertainties cancellation. For 104Pd, and preliminary for 108Pd, the respective values of C = 1.18(3) and C = 1.13(4) reveal an enhanced contribution of the protons relative to the neutrons to the excitation, while a smaller effect is found for 106Pd, C = 1.06(3) and for 110Pd, C 1.07(3), in comparison with the value C 1.00 expected for homogenous collective excitations. (author)
Coulomb nuclear interference with deuterons in even palladium isotopes
Rodrigues, M.R.D.; Rodrigues, C.L.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J. L.M. [Sao Paulo Univ., SP (Brazil); Ukita, G.M. [Universidade de Santo Amaro, SP (Brazil). Faculdade de Psicologia
2004-09-15
Angular distributions for the inelastic scattering of 13.0 MeV deuterons on {sup 104,106,108,110}Pd were measured with the Sao Paulo Pelletron-Enge-Spectrograph facility in the range of 12{sup 0} {<=}{theta}{sub lab} {<=}64{sup 0}. A Coulomb-Nuclear Interference analysis, employing the Distorted Wave Born Approximation with the Deformed Optical Model as transition potential, under well established global optical parameters, was applied to the first quadrupolar excitations. The values of C = {delta}{sub LC}/{delta}{sub LN}, the ratio of charge to isoscalar deformation lengths, and of ({delta}{sub LN}){sup 2} were extracted through the comparison of experimental and predicted cross section angular distributions. The ratios of reduced charge to isoscalar transition probabilities, B(EL) to B(ISL) respectively, are related to the square of the parameter C and were thus obtained with the advantage of scale uncertainties cancellation. For {sup 104}Pd, and preliminary for {sup 108}Pd, the respective values of C = 1.18(3) and C = 1.13(4) reveal an enhanced contribution of the protons relative to the neutrons to the excitation, while a smaller effect is found for {sup 106}Pd, C = 1.06(3) and for {sup 110}Pd, C 1.07(3), in comparison with the value C 1.00 expected for homogenous collective excitations. (author)
The elastic and inelastic α-scattering from the isotopes 110Cd, 112Cd, 114Cd, 116Cd and 124Te, 126Te, 128Te is investigated in the region of the Coulomb barrier. The elastic excitation functions at scattering angles of 1750, +-1200, +-600 and the inelastic excitation functions for the first 0+ → 2+ transition at the angle 1750 were thus measured for these isotopes. The evaluation of the Coulomb excitation within the inelastic excitation gave the B(E2, 0+ → 2+) values for these transitions. The experimentally measured cross sections could be fitted to all isotopes in the total energy range between 7 MeV and 17 MeV within the framework of a DWBA analysis using a deformed 4-parameter potential. (orig./LH)
Coulomb dissociation and momentum distributions for 11Li → 9Li + n + n breakup reactions
Momentum distributions for the 11Li → 9Li+n+n breakup reaction, generated by Coulomb dipole excitations, axe calculated in a 3-body model for 11Li. The relative momentum distribution of the two neutrons is in good agreement with recent 3-body coincidence measurements but the momentum distribution for the 9Li recoil and the decay energy spectrum are much narrower than observed. These discrepancies may be due to higher order dynamical effects which have been ignored
Orbital Ordering Induced by Direct Coulomb Repulsion
HUANG Yuan-Yie; ZHANG Yu-Heng
2011-01-01
We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering (OO) based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction (OO-I) between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.
Coulomb interaction in few-nucleon systems
Mathematical aspects of scattering quantum theory are considered. A brief review of methods proposed for solution of the following problems is presented: a) description of properties of resolvant nucleus for the operator of energy of three charged particles system, 2) definition of total system of Coulomb wave functions, 3) definition of unitary Coulomb scattering operator, 4) study of singularity of its nucleus, 5) establishing of relation between stationary and non stationary formulations of the scattering theory. The solution of these problems is obtained by means of a new form of Faddeev integral equations. The equations are formulated and studied in configuration space
Testing of Coulomb-Volkov functions
A time-dependent generalization of the Siegert theorem is applied to test the accuracy of the Coulomb-Volkov functions (CVFs) widely used for the description of electron motion in a laser field combined with the Coulomb field of the atomic core. Free-free transitions in the case of arbitrary elliptic polarization of the electromagnetic field are investigated. It is shown that the ratio between the strength of the light wave electric field and its frequency (in atomic units) has crucial importance for estimation of the CVF accuracy. (author)
Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method
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.
Module of System Galactica with Coulomb's Interaction
Smulsky, Joseph J
2014-01-01
The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.
On Confinement in Coulomb Gauge QCD
Full text: We study the quark propagator in Coulomb gauge QCD and employ the corresponding results to calculate meson properties. We demonstrate a mechanism how color non-singlets as e.g. diquarks in the color anti-triplet state are confined. (author)
Bound - states for truncated Coulomb potentials
Odeh, Maen; Mustafa, Omar
2000-01-01
The pseudoperturbative shifted - $l$ expansion technique PSLET is generalized for states with arbitrary number of nodal zeros. Bound- states energy eigenvalues for two truncated coulombic potentials are calculated using PSLET. In contrast with shifted large-N expansion technique, PSLET results compare excellently with those from direct numerical integration.
Coulomb drag in coherent mesoscopic systems
Mortensen, Niels Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2001-01-01
We present a theory for Coulomb drag between two mesoscopic systems. Our formalism expresses the drag in terms of scattering matrices and wave functions, and its range of validity covers both ballistic and disordered systems. The consequences can be worked out either by analytic means, such as the...
BRST invariance in Coulomb gauge QCD
Andrasi, A
2015-01-01
In the Coulomb gauge, the Hamiltonian of QCD contains terms of order h^2, identified by Christ and Lee, which are non-local but instantaneous. The question is addressed how these terms fit in with BRST invariance. Our discussion is confined to the simplest, O(g^4), example.
BRST invariance in Coulomb gauge QCD
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.
Frictional Coulomb drag in strong magnetic fields
Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang;
1997-01-01
A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is...
Coulomb functions with complex angular momenta
The subroutine CCOULM calculates regular and irregular Coulomb functions and their derivatives associated with complex angular momenta. This program may thus be used, for example, in locating Regge poles that appear in atomic and nuclear scattering problems. The calculation utilized the asymptotic expansion method of Froeberg. (Auth.)
Coulomb drag in coherent mesoscopic systems
Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2001-01-01
random matrix theory, or by numerical simulations. We show that Coulomb drag is sensitive to localized states. which usual transport measurements do not probe. For chaotic 2D systems we find a vanishing average drag, with a nonzero variance. Disordered 1D wires show a finite drag, with a large variance...
18Ne Excited States Two-Proton Decay
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.
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.
Hamzavi, Majid
2012-01-01
The exact Dirac equation for the energy-dependent Coulomb (EDC) potential including a Coulomb-like tensor (CLT) potential has been studied in the presence of spin and pseudospin (p-spin) symmetries with arbitrary spin-orbit quantum number The energy eigenvalues and corresponding eigenfunctions are obtained in the framework of asymptotic iteration method (AIM). Some numerical results are obtained in the presence and absence of EDC and CLT potentials.
Sensor Craft Control Using Drone Craft with Coulomb Propulsion System
Joe, Hyunsik
2005-01-01
The Coulomb propulsion system has no exhaust plume impingement problem with neighboring spacecraft and does not contaminate their sensors because it requires essentially no propellant. It is suitable to close formation control on the order of dozens of meters. The Coulomb forces are internal forces of the formation and they influence all charged spacecraft at the same time. Highly nonlinear and strongly coupled equations of motion of Coulomb formation makes creating a Coulomb control method a...
A measurement of the evolution of Interatomic Coulombic Decay in the time domain
Trinter, F; Weller, M; Waitz, M; Pitzer, M; Voigtsberger, J; Schober, C; Kastirke, G; Müller, C; Goihl, C; Burzynski, P; Wiegandt, F; Bauer, T; Wallauer, R; Sann, H; Kalinin, A; Schmidt, L Ph H; Schöffler, M; Sisourat, N; Jahnke, T
2013-01-01
During the last 15 years a novel decay mechanism of excited atoms has been discovered and investigated. This so called ''Interatomic Coulombic Decay'' (ICD) involves the chemical environment of the electronically excited atom: the excitation energy is transferred (in many cases over long distances) to a neighbor of the initially excited particle usually ionizing that neighbor. It turned out that ICD is a very common decay route in nature as it occurs across van-der-Waals and hydrogen bonds. The time evolution of ICD is predicted to be highly complex, as its efficiency strongly depends on the distance of the atoms involved and this distance typically changes during the decay. Here we present the first direct measurement of the temporal evolution of ICD using a novel experimental approach.
Spin diffusion in doped semiconductors: the role of Coulomb interactions
D'Amico, Irene; Vignale, Giovanni
2000-01-01
We examine the effect of the Coulomb interaction on the mobility and diffusion of spin packets in doped semiconductors. We find that the diffusion constant is reduced, relative to its non-interacting value, by the combined effect of Coulomb-enhanced spin susceptibility and spin Coulomb drag. In ferromagnetic semiconductors, the spin diffusion constant vanishes at the ferromagnetic transition temperature.
Creation of planar charged fermions in Coulomb and Aharonov-Bohm potentials
Khalilov, V R
2013-01-01
The creation of charged fermions from the vacuum by a Coulomb field in the presence of an Aharonov--Bohm (AB) potential are studied in 2+1 dimensions. The process is governed by a (singular) Dirac Hamiltonian that requires the supplementary definition in order for it to be treated as a self-adjoint quantum-mechanical operator. By constructing a one-parameter self-adjoint extension of the Dirac Hamiltonian, specified by boundary conditions, we describe the (virtual bound) quasistationary states with "complex energy" emerging in an attractive Coulomb potential, derive for the first time, complex equations (depending upon the electron spin and the extension parameter) for the quasistationary state "complex energy". The constructed self-adjoint Dirac Hamiltonians in Coulomb and AB potentials are applied to provide a correct description to the low-energy electron excitations, as well as the creation of charged quasiparticles from the vacuum in graphene by the Coulomb impurity in the presence of AB potential. It is...
Coulomb-interaction effects on the electronic structure of radially polarized excitons in nanorings
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.
Long range effects on the optical model of 6He around the Coulomb barrier
Fernandez-Garcia, J P; Alvarez, M A G; Moro, A M
2010-01-01
We present an optical model (OM) analysis of the elastic scattering data of the reactions 6He+27Al and 6He+208Pb at incident energies around the Coulomb barrier. The bare part of the optical potential is constructed microscopically by means of a double folding procedure, using the Sao Paulo prescription without any renormalization. This bare interaction is supplemented with a Coulomb dipole polarization (CDP) potential, which takes into account the effect of the dipole Coulomb interaction. For this CDP potential, we use an analytical formula derived from the semiclassical theory of Coulomb excitation. The rest of the optical potential is parametrized in terms of Woods-Saxon shapes. In the 6He+208Pb case, the analysis confirms the presence of long range components, in agreement with previous works. Four-body Continuum-Discretized Coupled-Channels calculations have been performed in order to better understand the features of the optical potentials found in the OM analysis. This study searches to elucidate some ...
Molecular structure by Coulomb explosion imaging of stored molecular ions
An experimental scheme, which combines Coulomb explosion imaging (CEI) with storage of fast molecular ions, has been introduced recently at the TSR heavy ion storage ring facility in Heidelberg. CEI is an experimental technique that provides direct observation of the nuclear conformations within small molecules. The combination of CEI with the storage ring technique enables the control of the internal excitation of the measured molecules, which is an essential condition to the interpretation of CEI results in terms of ''structure'' assigned to specific molecular states. This structure is measured as a function of storage time, thus enabling one to study processes of slow intramolecular dynamics such as isomerization, metastable states, etc. Moreover in this scheme, CEI can be used as a diagnostic tool for the intramolecular excitation, while other molecular interactions (e.g. with electrons or photons) are investigated. In this report, the CEI principle and the new experimental setup are described with an emphasis on the new prospects for studies in molecular physics. CEI measurements of stored CH2+ and NH2+ molecular ions are presented. The study of the angular distribution in these molecules as a function of their vibrational relaxation to the ground state, reveals unexpected behavior near the linear conformation which is inconsistent with the current adiabatic theories
Short-time dynamics of correlated quantum Coulomb systems
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
Manifestation of nuclear cluster structure in Coulomb sums
Buki, A Yu
2016-01-01
Experimental Coulomb sum values of 6^Li and 7^Li nuclei have been obtained, extending the earlier reported momentum transfer range of Coulomb sums for these nuclei up to q = 0.750 ... 1.625 fm^-1. The dependence of the Coulomb sums on the momentum transfers of 6^Li and 7^Li is shown to differ substantially from similar dependences for all the other nuclei investigated. Relationship between the nuclear cluster structure and Coulomb sums has been considered. The momentum transfer value, above which the Coulomb sum becomes constant, is found to be related to the cluster isolation parameter x, which characterizes the degree of nuclear clusterization.
Coulomb interaction in Eliashberg theory of superconductivity
Davydov, Arkady; Sanna, Antonio [Max-Planck-Institute of Microstructure Physics, Halle (Saale) (Germany)
2013-07-01
The Eliashberg theory of superconductivity allows to describe materials with strong pairing interaction. In the non magnetic case it leads to a system of coupled integral multidimensional equations. Computational costs are usually reduced by an isotropic limit, and by restricting the Coulomb interaction to the use of one single parameter, μ{sup *}, often chosen to give the experimental T{sub c}. In this work we present the parameter-free approach in which the screened Coulomb interaction fully accounted within the Random Phase Approximation, entering the Eliashberg's equations on the same footing as the phononic interaction. We will compare this approach with Density Functional Theory for Superconductors where the corresponding approximation leads to a good agreement with experiments.
Feynman rules for Coulomb gauge QCD
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: ► In Coulomb gauge QCD, we re-express Christ–Lee terms in the Hamiltonian as pseudo-Feynman integrals. ► This gives a subgraph structure, and allows the ordinary renormalization process. ► It also leads to cancellation of energy-divergences.
Coulomb Bound States of Strongly Interacting Photons
Maghrebi, M. F.; Gullans, M. J.; Bienias, P.; Choi, S.; Martin, I.; Firstenberg, O.; Lukin, M. D.; Büchler, H. P.; Gorshkov, A. V.
2015-09-01
We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasibound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wave function resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.
Coulomb drag in topological insulator films
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.
Coulomb bound states of strongly interacting photons
Maghrebi, M F; Bienias, P; Choi, S; Martin, I; Firstenberg, O; Lukin, M D; Büchler, H P; Gorshkov, A V
2015-01-01
We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.
Coulomb interaction in Eliashberg theory of superconductivity
The Eliashberg theory of superconductivity allows to describe materials with strong pairing interaction. In the non magnetic case it leads to a system of coupled integral multidimensional equations. Computational costs are usually reduced by an isotropic limit, and by restricting the Coulomb interaction to the use of one single parameter, μ*, often chosen to give the experimental Tc. In this work we present the parameter-free approach in which the screened Coulomb interaction fully accounted within the Random Phase Approximation, entering the Eliashberg's equations on the same footing as the phononic interaction. We will compare this approach with Density Functional Theory for Superconductors where the corresponding approximation leads to a good agreement with experiments.
Coulomb breakup of neutron-rich $^{29,30}$Na isotopes near the island of inversion
Rahaman, A; Aumann, T; Beceiro-Novo, S; Boretzky, K; Caesar, C; Carlson, B V; Catford, W N; Chakraborty, S; Chartier, M; Cortina-Gil, D; Angelis, G De; Gonzalez-Diaz, D; Emling, H; Fernandez, P Diaz; Fraile, L M; Ershova, O; Geissel, H; Jonson, B; Johansson, H; Kalantar-Nayestanaki, N; Krücken, R; Kröll, T; Kurcewicz, J; Langer, C; Bleis, T Le; Leifels, Y; Münzenberg, G; Marganiec, J; Nilsson, T; Nociforo, C; Nowacki, F; Najafi, A; Panin, V; Paschalis, S; Plag, R; Poves, A; Ray, I; Reifarth, R; Rigollet, C; Ricciardi, V; Rossi, D; Scheit, H; 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
2016-01-01
First results are reported on the ground state configurations of the neutron-rich $^{29,30}$Na isotopes, obtained via Coulomb dissociation (CD) measurements as a method of the direct probe. The invariant mass spectra of those nuclei have been obtained through measurement of the four-momentum of all decay products after Coulomb excitation on a $^{208}Pb$ target at energies of 400-430 MeV/nucleon using FRS-ALADIN-LAND setup at GSI, Darmstadt. Integrated Coulomb-dissociation cross-sections (CD) of 89 $(7)$ mb and 167 $(13)$ mb up to excitation energy of 10 MeV for one neutron removal from $^{29}$Na and $^{30}$Na respectively, have been extracted. The major part of one neutron removal, CD cross-sections of those nuclei populate core, in its' ground state. A comparison with the direct breakup model, suggests the predominant occupation of the valence neutron in the ground state of $^{29}$Na${(3/2^+)}$ and $^{30}$Na${(2^+)}$ is the $d$ orbital with small contribution in the $s$-orbital which are coupled with ground ...
Coulomb blockade at almost perfect transmission
Matveev, K. A.
1994-01-01
We study the equilibrium properties of a quantum dot connected to a bulk lead by a single-mode quantum point contact. The ground state energy and other thermodynamic characteristics of the grain show periodic dependence on the gate voltage (Coulomb blockade). We consider the case of almost perfect transmission, and show that the oscillations exist as long as the transmission coefficient of the contact is less than unity. Near the points where the dot charge is half-integer the thermodynamic c...
Chaos near the Coulomb barrier. Nuclear molecules
The present work examines in detail the classical behavior of the α + 14C and the 12C + 12C(O+) collison at energies near the Coulomb barrier. The long-time motion of the compound nuclear system is identified in terms of its classical quasiperiodic and chaotic behavior. The consequences of this motion are discussed and interpreted in terms of the evolution of the system along a dynamical energy surface. 45 references
Lorenz or Coulomb in Galilean Electromagnetism ?
Rousseaux, Germain
2005-01-01
PDF version International audience Galilean Electromagnetism was discovered thirty years ago by Levy-Leblond & Le Bellac. However, these authors only explored the consequences for the fields and not for the potentials. Following De Montigny & al., we show that the Coulomb gauge condition is the magnetic limit of the Lorenz gauge condition whereas the Lorenz gauge condition applies in the electric limit of Lévy-Leblond & Le Bellac. Contrary to De Montigny & al. who used Galilean tensor c...
Coulomb drag in the mesoscopic regime
Mortensen, N.A.; Flensberg, Karsten; Jauho, Antti-Pekka
2002-01-01
We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....
Coulomb drag in the mesoscopic regime
Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2002-01-01
We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....
Module of System Galactica with Coulomb's Interaction
Joseph J. Smulsky
2014-12-01
Full Text Available The system Galactica of free access is supplemented module for the Coulomb interaction. It is based on a high-precision method for solving differential equations of motion of N charged particles. The paper presents all the theoretical and practical issues required to use this module of system Galactica so that even the beginning researcher could study the motion of particles, atoms and molecules.
Coulomb dissociation studies for astrophysical thermonuclear reactions
Motobayashi, T. [Dept. of Physics, Rikkyo Univ., Toshima, Tokyo (Japan)
1998-06-01
The Coulomb dissociation method was applied to several radiative capture processes of astrophysical interest. The method has an advantage of high experimental efficiency, which allow measurements with radioactive nuclear beams. The reactions {sup 13}N(p,{gamma}){sup 14}O and {sup 7}Be(p,{gamma}){sup 8}B are mainly discussed. They are the key reaction in the hot CNO cycle in massive stars and the one closely related to the solar neutrino problem, respectively. (orig.)
Coulomb drag in the mesoscopic regime
Mortensen, N. Asger; Flensberg, Karsten; Jauho, Antti-Pekka
We present a theory for Coulomb drug between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic...... average drag for chaotic 2D-systems and dominating fluctuations of drag between quasi-ballistic wires with almost ideal transmission....
Dynamics of Coulombic and gravitational periodic systems
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.
Elastic Coulomb breakup of $^{34}$Na
Singh, G; Chatterjee, R
2016-01-01
Purpose : The aim of this paper is to study the elastic Coulomb breakup of $^{34}$Na on $^{208}$Pb to give us a core of $^{33}$Na with a neutron and in the process we try and investigate the one neutron separation energy and the ground state configuration of $^{34}$Na. 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 $^{34}$Na on $^{208}$Pb 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 $^{34}$Na. The average momentum results along with energy-angular calculations indicate $^{34}$Na to ha...
The Coulomb-nuclear force interference in the system 32S + 60Ni
For the reaction 60Ni(32S,32S*)60Ni* using particle-γ-coincidences the excitation functions of 32S(2+1) and 60Ni(2+1) for projectile energies of 70-100 MeV as well as with Si single counters the angular distribution of the elastically and inelastically scattered 32S ions for incident energies of 90, 95, and 100 MeV were measured. A comparison of the measurements with the results of different computer codes led to following results: 1.) At the determination of the static quadrupole moment Q2 of 32S using the reorientation effect the influence of the nuclear force can be neglected for projectile energies Esub(P) 32S the value Q2 = -0.18 +- 0.04 eb was found. (Hereby destructive interference with the virtual excitation of the 2+2-state is assumed). 3.) For projectile energies Esub(P) >= 72 MeV at which the excitation by nuclear forces was small against the Coulomb excitation, an evaluation of the excitation function of 32S(2+1) by the semiclassical code NCL, which regards the influence of the nuclear interaction approximatively, yielded values for the static quadrupole moment, which agree within the measurement errors with the above value. 4.) For the quantitative analysis of the measured angular distributions a quantum mechanical CC-code was required. 5.) Using the semiclassical CC-code NCL an illustrative and detailed interpretation of the excitation functions of 32S(2+1) and 60Ni(2+1) could be given. 6.) The code NCL allows the study of the influence of the Coulomb-nuclear force interference on the temporal behaviour of the excitation process. 7.) Using the code NCL the angular distribution of the decay γ quanta for a fixed particle-scattering angle theta approx. 0 in dependence on the incident energy was calculated. (orig.)
Iodine ions of high charge states are observed upon irradiation of methyl iodide clusters with an intense femtosecond laser pulse. All signals from multicharged ions exhibit a peak splitting in the time-of-flight mass spectra, indicating their origin from a Coulomb explosion process. These main peaks are accompanied by smaller peaks attributed to field ionization of highly charged species in the ion optics of the TOF mass spectrometer. It is shown that highly charged atomic ions formed from Coulomb explosion, upon interaction with electric field close to the mesh, can lose another electron leading to the formation of even higher charged species. The observation of this charge stripping process is evidence for the formation of highly excited ions in the course of the Coulomb explosion process, providing new insights into the mechanisms of femtosecond ionization involving multi-electron loss. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)
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
Systematic study of breakup effects on complete fusion at energies above the Coulomb barrier
Wang, Bing; Gomes, P R S; Zhao, En-Guang; Zhou, Shan-Gui
2014-01-01
A large number of complete fusion excitation functions of reactions including the breakup channel were measured in recent decades, especially in the last few years. It allows us to investigate the systematic behavior of the breakup effects on the complete fusion cross sections. To this end, we perform a systematic study of the breakup effects on the complete fusion cross sections at energies above the Coulomb barrier. The reduced fusion functions $F(x)$ are compared with the universal fusion functions which are used as a uniform standard reference. The complete fusion cross sections at energies above the Coulomb barrier are suppressed by the breakup of projectiles. This suppression effect for reactions induced by the same projectile is independent of the target and mainly determined by the lowest energy breakup channel of the projectile. There holds a good exponential relation between the suppression factor and the energy corresponding to the lowest breakup threshold.
Coulomb drag in multiwall armchair carbon nanotubes
Lunde, A.M.; Jauho, Antti-Pekka
2004-01-01
We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...
Coulomb field in a constant electromagnetic background
Adorno, T C; Shabad, A E
2016-01-01
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 Euler-Heisenberg effective Lagrangian. Linear electric response to 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, 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.
Dynamic properties of the Coulomb fission
The heavy ion induced fission after quasi-elastic scattering was studied in the systems 208Pb -> 238U for central collision at energies below the Coulomb barrier and 238U -> 238U for peripheral collisions at scattering angles smaller than the grazing angle. The dynamical properties and the phase-space distributions of the reactions could be determined by the method of the kinematical coincidences where positions and time-of-flight of two fission fragments and a scattered projectile-like nucleus were measured at the same time in large-area gas-filled parallel plate counters. (orig./HSI)
Multiple Coulomb scattering in thin silicon
We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50–140 μm) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Student's t distribution is developed and compared to the data
Resonances in the two centers Coulomb system
Seri, Marcello
2012-09-14
In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.
Expectation values in relativistic Coulomb problems
Suslov, Sergei K, E-mail: sks@asu.ed [School of Mathematical and Statistical Sciences and Mathematical, Computational, and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1804 (United States)
2009-09-28
We evaluate the matrix elements (Or{sup p}), where O = {l_brace}, {beta},i{alpha}n{beta}{r_brace} are the standard Dirac matrix operators and the angular brackets denote the quantum-mechanical average for the relativistic Coulomb problem, in terms of generalized hypergeometric functions {sub 3}F{sub 2}(1) for all suitable powers. Their connections with the Chebyshev and Hahn polynomials of a discrete variable are emphasized. As a result, we derive two sets of Pasternack-type matrix identities for these integrals, when p -> -p - 1 and p -> -p - 3, respectively. Some applications to the theory of hydrogenlike relativistic systems are reviewed.
Ordering transitions induced by Coulomb interactions
We briefly review recent progress in treating phase transitions to ordered states driven by Coulomb interactions. Wigner crystallization of the one-component plasma, in the degenerate Fermi limit and in the classical limit, is the foremost example and developments in its theory are discussed in some detail. Attention is also given to quasi-twodimensional realizations of the plasma model in the laboratory. The usefulness of these ideas in relation to freezing and ordering transitions is illustrated with reference to alkali metals, elemental and polar semiconductors, and various types of ionic systems (molten salts, colloidal suspensions and astrophysical plasmas). (author). 70 refs, 5 figs
Feynman rules for Coulomb gauge QCD
Andrasi, A
2012-01-01
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 subgraph structure of ordinary Feynamn graphs. The CL terms do not have subgraph structure. We show how to carry out enormalization in the presene of CL erms, by re-expressing these as `pseudo-Feynman' inegrals. We also explain how energy divergences cancel.
Overlap Quark Propagator in Coulomb Gauge QCD
Mercado, Ydalia Delgado; Schröck, Mario
2014-01-01
The chirally symmetric Overlap quark propagator is explored in Coulomb gauge. This gauge is well suited for studying the relation between confinement and chiral symmetry breaking, since confinement can be attributed to the infrared divergent Lorentz-vector dressing function. Using quenched gauge field configurations on a $20^4$ lattice, the quark propagator dressing functions are evaluated, the dynamical quark mass is extracted and the chiral limit of these quantities is discussed. By removing the low-lying modes of the Dirac operator, chiral symmetry is artificially restored. Its effect on the dressing functions is discussed.
Electroweak Sudakov logarithms in the Coulomb gauge
Beenakker, W.; Werthenbach, A.
2000-01-01
We describe a formalism for calculating electroweak Sudakov logarithms in the Coulomb gauge. This formalism is applicable to arbitrary electroweak processes. For illustration we focus on the specific reactions e^+e^- -> f \\bar{f} and e^+e^- -> W_T^+W_T^-, W_L^+W_L^-, which contain all the salient details of dealing with the various types of particles. We discuss an explicit two-loop calculation and have a critical look at the (non-)exponentiation and factorisation properties of the Sudakov lo...
Resonances in the two centers Coulomb system
In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.
Action principle for Coulomb collisions in plasmas
Hirvijoki, Eero
2015-01-01
In this letter we derive an action principle for Coulomb collisions in plasmas. Although no natural Lagrangian exists for the Landau-Fokker-Planck equation, an Eulerian variational formulation is found considering the system of partial differential equations that couple the distribution function and the Rosenbluth potentials. Exact conservation laws are derived after generalizing the energy-momentum stress tensor for second order Lagrangians and, in the case of a test-particle population in a given plasma background, the action principle is shown to correspond to the Langevin equation for individual particles. Being suitable for discretization, the presented action allows construction of variational integrators. Numerical implementation is left for a future study.
Mapping chiral symmetry breaking in the excited baryon spectrum
Bicudo, Pedro; Llanes-Estrada, Felipe J; Van Cauteren, Tim
2016-01-01
We study the conjectured "Insensitivity to Chiral Symmetry Breaking" in the highly excited light baryon spectrum. While the experimental spectrum is being measured at JLab and CBELSA/TAPS, this insensitivity remains to be computed theoretically in detail. As the only existing option to have both confinement, highly excited states and chiral symmetry, we adopt the truncated Coulomb gauge formulation of QCD, considering a linearly confining Coulomb term. Adopting a systematic and numerically intensive variational treatment up to 12 harmonic oscillator shells we are able to access several angular and radial excitations. We compute both the excited spectra of $I=1/2$ and $I=3/2$ baryons, up to large spin $J=13/2$, and study in detail the proposed chiral multiplets. While the static-light and light-light spectra clearly show chiral symmetry restoration high in the spectrum, the realization of chiral symmetry is more complicated in the baryon spectrum than earlier expected.
Lim, Edward C
1974-01-01
Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab
Static color-Coulomb force from restriction to Gribov region
The static color-Coulomb interaction potential is determined as the solution of a non-linear integral equation. This equation expresses a self-consistency condition which arises in the Coulomb Hamiltonian formulation of lattice gauge theory when the restriction to the interior of the Gribov horizon is implemented. The potential obtained is in qualitatively agreement with expectations, being Coulombic with logarithmic corrections at short range, and confining at long range. (author)
Coulomb sum rules in the relativistic Fermi gas model
Coulomb sum rules are studied in the framework of the Fermi gas model. A distinction is made between mathematical and observable sum rules. Differences between non-relativistic and relativistic Fermi gas predictions are stressed. A method to deduce a Coulomb response function from the longitudinal response is proposed and tested numerically. This method is applied to the 40Ca data to obtain the experimental Coulomb sum rule as a function of momentum transfer
Vacuum structure of the Coulomb gas in two dimensions
We study the plasma phase of the two-dimensional Coulomb gas in the small density limit. The analysis is done using the correspondence of the Coulomb gas with the 1 + 1 sine-Gordon model, which has been exactly solved by the quantum inverse method. We construct the correct vacuum of the field theory, improving the former results. We obtain exact results for the Coulomb gas, which confirm the previous perturbative calculations. (orig.)
Coulomb corrections for interferometry analysis of expanding hadron systems
The problem of the Coulomb corrections to the two-boson correlation functions for the systems formed in ultra-relativistic heavy ion collisions is considered for large effective system volumes. The modification of the standard zero-distance correction (so called Gamow or Coulomb factor) has been proposed for such a kind of systems. For the π+π+ and K+K+ correlation functions the analytical calculations of the Coulomb correction are compared with the exact numerical results. (author)
Effect of Coulomb interaction on multi-electronwave packet dynamics
Shiokawa, T. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571 (Japan); Takada, Y. [Faculty of Engineering, Tokyo University of Science, Chiyoda, Tokyo, 102-0073, Japan and CREST, Japan Science and Technology Agency (Japan); Konabe, S.; Hatsugai, Y. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and CREST, Japan Science and Technology Agency (Japan); Muraguchi, M. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and CREST, Japan Science and Technology Agency (Japan); Endoh, T. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and Center for Spintronics Integrated Systems, Tohoku University, Sendai, 980-8577, Japan and CREST, Japan Science and Technology Agency (Japan); Shiraishi, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and Center for Computational Science, University of Tsukuba, Tsukuba, 305-8577, Japan and CREST, Japan Science and Technology Agency (Japan)
2013-12-04
We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.
Nuclear excitation in positron-K-electron annihilation
Kaliman, Z.; Pisk, K.; Logan, B.A.
1987-05-01
We have calculated the cross section for nuclear excitation during positron-K-electron annihilation. The calculations allow for the effect of the nuclear Coulomb field and for relativistic effects. The results are compared to earlier predictions which were derived using the Born approximation, and to renormalized Born approximation predictions. Our calculated cross sections are well below the available experimental values.
Laser-assisted electron-ion scattering by the Coulomb-Glauber approximation
In this paper, we extend the Coulomb-Glauber approximation to charged particles scattering processes in the presence of a laser field. With this method, laser-assisted electron scattering by hydrogen-like ions is studied. Numerical results of the elastic and 1s→2s, 1s→2p excitation scattering differential cross sections are obtained. Based on these results we discuss and compare with the Born approximation, the selection rules, the dressing effects and the use of the closure approximation in the calculation of the S-matrix. The cross section of the elastic scattering as a function of the charge number Z has also been shown. (author)
Elastic Coulomb breakup of 34Na
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
Spherical Calogero model with oscillator/Coulomb potential: quantum case
Correa, Francisco; Lechtenfeld, Olaf; Nersessian, Armen
2016-01-01
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.
Coulomb interaction between a spherical and a deformed nuclei
Takigawa, N; Ihara, N; Takigawa, Noboru; Rumin, Tamanna; Ihara, Naoki
2000-01-01
We present analytic expressions of the Coulomb interaction between a spherical and a deformed nuclei which are valid for all separation distance. We demonstrate their significant deviations from commonly used formulae in the region inside the Coulomb radius, and show that they remove various shortcomings of the conventional formulae.
Coulomb corrections in the low-energy scattering
Renormalization of the coefficients of the ''effective range expansion'' is considered for the short-range Coulomb problem. The exactly solvable model of the Coulomb plus short range potential is considered. Exact solutions are compared with approximations frequently used in the theory of hadronic atoms
Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems
Sleutels, T.H.J.A.; Darus, L.; Hamelers, H.V.M.; Buisman, C.J.N.
2011-01-01
To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was invest
Correlated Coulomb drag in capacitively coupled quantum-dot structures
Kaasbjerg, Kristen; Jauho, Antti-Pekka
2016-01-01
We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven 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 which accounts for higher-order tunneling (cotunneli...
Antilocalization of Coulomb Blockade in a Ge-Si Nanowire
Higginbotham, Andrew P.; Kuemmeth, Ferdinand; Larsen, Thorvald Wadum;
2014-01-01
The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge-Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak...
Coulomb blockade of spin-dependent shuttling
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.
Study on Coulomb explosions of ion mixtures
Boella, E; D'Angola, A; Coppa, G; Silva, L O
2015-01-01
The paper presents a theoretical work on the dynamics of Coulomb explosion for spherical nanoplasmas composed by two different ion species. Particular attention has been dedicated to study the energy spectra of the ions with the larger charge-to-mass ratio. The connection between the formation of shock shells and the energy spread of the ions has been the object of a detailed analysis, showing that under particular conditions the width of the asymptotic energy spectrum tends to become very narrow, which leads to a multi-valued ion phase-space. The conditions to generate a quasi mono-energetic ion spectrum have been rigorously demonstrated and verifed by numerical simulations, using a technique that, exploiting the spherical symmetry of the problem, allows one to obtain very accurate and precise results.
Gauge Theories on the Coulomb branch
Schwarz, John H
2014-01-01
We construct the world-volume action of a probe D3-brane in $AdS_5 \\times S^5$ with $N$ units of flux. It has the field content, symmetries, and dualities of the $U(1)$ factor of ${\\cal N} =4$ $U(N+1)$ super Yang--Mills theory, spontaneously broken to $U(N) \\times U(1)$ by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a `highly effective action' (HEA). We construct an $SL(2,Z)$ multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that it reproduces the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a `soliton bubble', which is interpreted as a phase boundary.
Relativistic Aharonov endash Bohm endash Coulomb problem
The ((2+1)-dimensional) Aharonov endash Bohm effect is analyzed for a spin-1/2 particle in the case that a 1/r potential is present. Scalar and vector couplings are each considered. It is found that the approach in which the flux tube is given a finite radius that is taken to zero only after a matching of boundary conditions does not give physically meaningful results. Specifically, the operations of taking the limit of zero flux tube radius and the Galilean limit do not commute. Thus there appears to be no satisfactory solution of the relativistic Aharonov endash Bohm endash Coulomb problem using the finite radius flux tube method. Copyright copyright 1996 Academic Press, Inc
Simplistic Coulomb Forces in Molecular Dynamics
Hansen, Jesper Schmidt; Schrøder, Thomas; Dyre, J. C.
2012-01-01
salt model the SF approximation overall reproduces the structural and dynamical properties as accurately as does the Wolf method. It is shown that the optimal Wolf damping parameter depends on the property in focus and that neither the potential energy nor the radial distribution function are useful...... measures for the convergence of the Wolf method to the Ewald summation method. The SF approximation is also tested for the SPC/Fw model of liquid water at room temperature, showing good agreement with both the Wolf and the particle mesh Ewald methods; this confirms previous findings [Fennell, C. J......In this paper we compare the Wolf method to the shifted forces (SF) method for efficient computer simulation of bulk systems with Coulomb forces, taking results from the Ewald summation and particle mesh Ewald methods as representing the true behavior. We find that for the Hansen–McDonald molten...
Coulomb vs. physical string tension on the lattice
Burgio, G; Reinhardt, H; Vogt, H
2015-01-01
We investigate the precise relationship between the Coulomb and the physical (Wilson) string tension on the lattice, as the former is generally known to give an upper bound for the latter. We give evidence that the two string tensions are in a one to one correspondence at zero temperature, while they become unrelated at finite temperatures. More precisely, we show that the standard lattice calculations of the Coulomb gauge confinement scenario are 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 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, although a true static Coulomb gauge order parameter for the phase transition is still elusive on the lattice.
The Coulomb potential in quantum mechanics and related topics
This dissertation consists of an analytic study of the Coulomb interaction in nonrelativistic quantum mechanics and some related topics. The author investigates in a number of self-contained articles various interesting and important properties of the Coulomb potential. Some of these properties are shared by other potentials which also play a role in quantum mechanics. For such related interactions a comparative study is made. The principal difficulties in the description of proton-deuteron scattering and break-up reactions, due to the Coulomb interaction, are studied by working out a simple model. The bound states are studied for the Coulomb plus Yamaguchi potential, for the symmetric shifted Coulomb potential, and for local potentials with an inverse-distance-squared asymptotic behaviour. (Auth.)
Excitation of continuum states in sup 7 Li and their decay by quantum tunneling
Utsunomiya, H; Yamagata, T; Ohta, M; Aoki, Y; Hirota, K; Ieki, K; Iwata, Y; Katori, K; Hamada, S; Lui, Y W; Schmitt, R P; Typel, S; Baur, G
1999-01-01
Strong forward-backward asymmetries were found in the recent alpha-t coincidence measurement of Coulomb breakup of 42 MeV- sup 7 Li via continuum states. The competition between E1 and E2 multipolarities and higher order effects in Coulomb excitation were investigated by solving the time-dependent Schroedinger equation. It is shown that higher order effects are an essential ingredient to the observed large asymmetries. The relevant reaction mechanism is discussed.
Takeuchi, Asia
2011-02-01
Full Text Available 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. [West J Emerg Med. 2011;12(1:77-83.
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
Excitation and photon decay of giant multipole resonances
A brief review of the excitation of giant multipole resonances via Coulomb excitation is given which emphasizes the very large cross sections that can be realized through this reaction for both isoscalar and isovector resonances. Discussion and results where available, are provide for the measurement of the photon decay of one and two phonon giant resonances. It is pointed out throughout the presentation that the use of E1 photons as a ''tag'' provides a means to observe weakly excited resonances that cannot be observed in the singles spectra. 14 refs., 12 figs., 1 tab
Dipole Excitations of Unstable Neutron-Rich Nuclei
Coulomb breakup of high-energy secondary beams of unstable nuclei serves in nuclear structure investigations of neutron-rich isotopes. A summary of the respective research activities at GSI is presented, covering isotopes from helium to oxygen. The breakup is mediated through dipole excitations in to the continuum. Non-resonant excitations in to the continuum near the dissociation threshold deliver information on the single-particle ground-state structure. Resonant excitation into the giant resonance domain is also observed. In addition, a brief outlook on future activities at GSI is given. (author)
Fusion below the Coulomb barrier (I)
Absolute normalization factors for fusion sections are determined with good precision by means of a system of four monitors that it measure Rutherford scattering. An excitation function for fusion of the system 37Cl + 55Ni, which presents the prospective behavior based on the one existent systematic is obtained. (Author)
Coulomb displacement energies in nuclei: a new approach
The neutron core polarization gives rise to an important correction to the direct Coulomb contribution when one calculates the Coulomb displacement energies. In the Hartree-Fock model it is shown that this correction is about 2% to 4.5% in medium and heavy nuclei. The core polarization as well as other higher order effects can be included by using a selfconsistent description of the analog state in a complete proton particle-neutron hole space. The Coulomb displacement energies in 48Ca, 88Sr and 208Pb have been calculated using Skyrme interactions SIII and SIV. A good agreement with experiment is obtained
Ionic Coulomb Blockade and Resonant Conduction in Biological Ion Channels
Kaufman, I Kh; Eisenberg, R S
2014-01-01
The conduction and selectivity of calcium/sodium ion channels are described in terms of ionic Coulomb blockade, a phenomenon based on charge discreteness and an electrostatic model of an ion channel. This novel approach provides a unified explanation of numerous observed and modelled conductance and selectivity phenomena, including the anomalous mole fraction effect and discrete conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The model is equally applicable to other nanopores.
Positron scattering from hydrogen atom with screened Coulomb potentials
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
Nuclear Interference effects in 8B sub-Coulomb breakup
Nunes, F. M.; Thompson, I.J.
1998-01-01
The breakup of $^8$B on $^{58}$Ni below the Coulomb barrier was measured recently with the aim of determining the Coulomb breakup components. We reexamine this reaction, and perform one step quantum-mechanical calculations that include E1, E2 and nuclear contributions. We show that the nuclear contribution is by no means negligible at the intermediate angular range where data was taken. Our results indicate that, for an accurate description of this reaction, Coulomb E1, E2 and nuclear process...
Deep inelastic scattering near the Coulomb barrier
Gehring, J.; Back, B.; Chan, K. [and others
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.
Accelerated Monte Carlo Methods for Coulomb Collisions
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.
Electron attraction mediated by Coulomb repulsion
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.
Monopole defects and magnetic Coulomb blockade
Magnetic monopoles, predicted by Dirac, entered a new paradigm with the discovery of emergent monopoles within dipole lattices known as bulk and artificial spin ices. The observation of monopoles in certain artificial systems, and their absence from other similar structures, is a significant puzzle. Connected artificial spin-ice structures attract much attention in terms of the possibility to read states electrically, and offer the possibility of monopole defect control via well-understood domain wall processes. Nevertheless, full comprehension of the underlying processes is lacking. Here, we establish one of the overriding components. We demonstrate using high-resolution scanning transmission x-ray microscopy (STXM) the cooperative process associated with two transverse domain walls that creates the monopole defect in NiFe. The feature size of the array is large compared to the exchange length in the ferromagnet, and the two transverse domain walls give a rich internal structure to the monopole defect vertex. The magnetic Coulomb repulsion between two domain walls carrying the same sign of magnetic charge stabilizes the monopole defects at fields greater than the depinning field for a single wall at that vertex. These observations allow us to form an overview of monopole defect control possibilities from extrinsic pinning as in Co arrays (the extreme extrinsic limit being isolated bar structures) to intrinsic pinning captured here.
Remarks on Coulomb effects in multiple scattering theories
We investigate the problem of introducing the Coulomb potential in Watson's multiple scattering expansion: in particular we formally analyse the implications for the optical potential and discuss various approximations necessary in order to make practical calculations
Fano effect through parallel-coupled double Coulomb islands
By means of the nonequilibrium Green function and equation of motion method, the electronic transport is theoretically studied through a parallel-coupled double quantum dot (DQD) in the presence of on-dot Coulomb interaction U. With focus on the quantum interference in the U-dominant parallel-coupled DQD, we find two types of Fano interferences in the conductance spectra. If the one-particle DQD bonding and antibonding bands are well separated from their Coulomb blockade counterparts, the main features of Fano interference in usual DQD systems are recovered with minor revisions. The most interesting is the hybridization between the antibonding state and the Coulomb counterpart of the bonding state, which gives rises to two new channels for Fano resonance. The Fano interference in the Coulomb hybridized systems can be controlled by the electrostatic and magnetic approaches, and exhibits properties quite different from what are reported in the noninteracting Fano-Anderson model
Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures
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.
COULOMB BLOCKADE OSCILLATIONS OF Si SINGLE-ELECTRON TRANSISTORS
王太宏; 李宏伟; 周均铭
2001-01-01
Coulomb blockade oscillations of Si single-electron transistors, which are fabricated completely by the conventional photolithography technique, have been investigated. Most of the single-electron transistors clearly show Coulomb blockade oscillations and these oscillations can be periodic by applying negative voltages to the in-plane gates. A shift of the peak positions is observed at high temperatures. It is also found that the fluctuation of the peak spacing cannot be neglected.
Primakoff effect: synchrotron and coulomb mechanisms of axion emission
For the first time the axion radiative emission by alternating electromagnetic field Fa → γa is considered due to Primakoff effect. As a concrete supplement, the synchrotron and Coulomb mechanisms are discussed and in the last case the alternating field is formed at the infinite motion of a charge in a Coulomb center field. The estimates for contributions of these effects into axion luminosity of magnetic neutron stars and the Sun are determined
Primakoff effect: Synchrotron and Coulomb mechanisms of axion emission
The Primakoff effect-induced radiative emission of axions by an alternating electromagnetic field, Fa → γa, is considered for the first time. The synchrotron mechanism and the Coulomb mechanism--in the latter case, the alternating field is formed when a charge executes an infinite motion in the field of a Coulomb center--are considered as specific examples. The contributions of these effects to the axion emissivity of magnetic neutron stars and of the Sun are estimated
Coulomb screening effect on the nuclear-pasta structure
Maruyama, Toshiki; Tatsumi, Toshitaka; Voskresensky, Dmitri N.; Tanigawa, Tomonori; Chiba, Satoshi; Maruyama, Tomoyuki
2004-01-01
Using the density functional theory (DFT) with the relativistic mean field (RMF) model, we study the non-uniform state of nuclear matter, ``nuclear pasta''. We self-consistently include the Coulomb interaction together with other interactions. It is found that the Coulomb screening effect is significant for each pasta structure but not for the bulk equation of state (EOS) of the nuclear pasta phase.
Coulomb's law modification in nonlinear and in noncommutative electrodynamics
Gaete, Patricio(Departmento de Física and Centro Científico-Tecnológico de Valparaíso, Universidad Técnica Federico Santa María, Valparaiso, Chile); Schmidt, Iván
2003-01-01
We study the lowest-order modifications of the static potential for Born-Infeld electrodynamics and for the $\\theta$-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 ($1/r^5$-type) to the Coulomb potential in Born-Infeld electrodynamics. However, the Coulomb nature of the potential (to order $e^2$) is preserved in noncommutative electrodynamics.
Kistryn, S; Bodek, K; Ciepal, I; Deltuva, A; Fonseca, A; Kalantar-Nayestanaki, N; Kis, M; Klos, B; Kozela, A; Mahjour-Shafiei, M; Micherdzinska, A; Sauer, P U; Stephan, E; Sworst, R; Zejma, J; Zipper, W; Kistryn, St.
2006-01-01
High precision cross-section data of the deuteron-proton breakup reaction at 130 MeV deuteron energy are compared with the theoretical predictions obtained with a coupled-channel extension of the CD Bonn potential with virtual Delta-isobar excitation, without and with inclusion of the long-range Coulomb force. The Coulomb effect is studied on the basis of the cross-section data set, extended in this work to about 1500 data points by including breakup geometries characterized by small polar angles of the two protons. The experimental data clearly prefer predictions obtained with the Coulomb interaction included. The strongest effects are observed in regions in which the relative energy of the two protons is the smallest.
A. I. Burshtein
2012-01-01
Full Text Available The Stern-Volmer constant is specified for the luminescence quenched by reversible ionization of excited molecules. The exergonic branch of the Rehm-Weller free energy dependence of this constant is known to be a plateau determined by irreversible ionization being under diffusion control. In the endergonic region the ionization is reversible and competes with the irreversible in-cage recombination of ions and their escape from the cage. At strong Coulomb attraction the latter phenomenon is shown to be negligible compared to the former that determines the shape and location of the descending branch of the Rehm-Weller curve. At weaker Coulomb attraction (at higher solvent polarity, this curve turns down at larger endergonicity. The experimental data obtained in solvents of different polarities are put in order and in full accordance with present theory.
Functional theory of extended Coulomb systems
A consistent formulation is presented for a functional theory of extended quantum many-particle systems with long-range Coulomb interactions, which extends the density-functional theory of Hohenberg and Kohn to encompass the theory of dielectrics formulated in terms of electric fields and polarization. We show that a complete description of insulators in the thermodynamic limit requires a functional of density and macroscopic polarization; nevertheless, for any insulator the state with zero macroscopic electric field can be considered a reference state that is a functional of the density alone. Dielectric phenomena involve the behavior of the material in the presence of macroscopic electric fields that induce changes of the macroscopic polarization from its equilibrium value in the reference state. In the thermodynamic limit there is strictly no ground state and constraints must be placed upon the electronic wave functions in order to have a well-defined energy functional; within these constrained subspaces the Hohenberg-Kohn theorems can be generalized in terms of the density and the change in the macroscopic polarization. The essential role of the polarization is shown by an explicit example of two potentials that lead to the same periodic density in a crystal, but different macroscopic electric fields and polarization. In the Kohn-Sham approach both the kinetic and the exchange-correlation energy are shown to depend upon the changes in polarization; this leads to generalized Kohn-Sham equations with a nonlocal operator. The effect can be traced to the polarization of the average exchange-correlation hole itself in the presence of macroscopic fields, which is essential for an exact description of static dielectric phenomena. copyright 1997 The American Physical Society
Coulomb sink effect on coarsening of metal nanostructures on surfaces
Yong HAN; Feng LIU
2008-01-01
We discuss Coulomb effects on the coarsening of metal nanostructures on surfaces. We have proposed a new concept of a "Coulomb sink" [Phys. Rev. Lett., 2004, 93: 106102] to elucidate the effect of Coulomb charging on the coarsening of metal mesas grown on semiconductor surfaces. A charged mesa, due to its reduced chemical potential, acts as a Coulomb sink and grows at the expense of neighboring neu-tral mesas. The Coulomb sink provides a potentially useful method for the controlled fabrication of metal nanostructures. In this article, we will describe in detail the proposed physical models, which can explain qualitatively the most salient fea-tures of coarsening of charged Pb mesas on the Si(111) sur-face, as observed by scanning tunneling microscopy (STM). We will also describe a method of precisely fabricating large-scale nanocrystals with well-defined shape and size. By using the Coulomb sink effect, the artificial center-full-hol-lowed or half-hollowed nanowells can be created.
Poisson's equation solution of Coulomb integrals in atoms and molecules
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.
Efros-Shklovskii variable range hopping conductivity without Coulomb gap
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.
Fermi-edge singularity in one-dimensional electron systems with long-range Coulomb interactions
Effects of long-range Coulomb interactions on the Fermi-edge singularity in optical spectra are investigated theoretically for one-dimensional spin-1/2 fermion systems with the use of the Tomonaga-Luttinger bosonization technique. Low-energy excitation spectrum near the Fermi level shows that dispersion of the charge-density fluctuation remains gapless but is nonlinear when the electron-electron (e-e) Coulomb interaction is of the x-1 type (i.e., an infinite force range). Temporal behavior of the current-current correlation function is calculated analytically for arbitrary force ranges, λe and λh, of the e-e and the electron-hole (e-h) Coulomb interactions. (i) When both the e-e and the e-h interactions have large but finite force ranges (λehmax[λe,λh]/vF. Corresponding optical spectrum near the Fermi edge (within an energy range of ℎvF/max[λe,λh]) exhibits the power-law divergence or the power-law convergence, which is an ordinary Fermi-edge singularity. (ii) When either the e-e or the e-h interaction is of the x-1 type (i.e., λe→∞ and/or λh→∞), an exponent of the correlation function is dependent on time to lead the faster decay than that of any power laws. Then the optical spectra show no power law dependence and always converge (become zero) at the Fermi edge, which is in striking contrast to the ordinary power-law singularity
Octupole deformation in 144,146Ba measured by Coulomb excitation of radioactive beams
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 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.
Measurements of octupole collectivity in Rn and Ra nuclei using Coulomb excitation
We propose to exploit the unique capability of HIE-ISOLDE to provide post-accelerated $^{221,222}$Rn and $^{222,226,228}$Ra ion beams for the study of octupole collectivity in these nuclei. We will measure E3 transition moments in $^{222}$Rn and $^{222,226,228}$Ra in order to fully map out the variation in E3 strenght in the octupole mass region with Z$\\thicksim$88 and N$\\thicksim$134. This will validate model calculations that predict different behaviour as a function of N. We will also locate the position of the parity doublet partner of the ground state in $^{221}$Rn, in order to test the suitability of odd-A radon isotopes for EDM searches.
A review of standard and new methods used in describing heavy ion processes is given in connection with a proposal of a heavy-ion machine at the National Laboratories of Frascati. The experimental proposal of the machine is shown and is compared with other machines. Introductory remarks are made about the semiclassical method, and more emphasis is put on the DWBA scheme, with some account of its approximations and shortcomings. An extensive presentation of the eikonal type methods for dealing with heavy ion processes is made in view of the applicability of these methods in the energy region 10-150 MeV/nucleon
Coulomb excitation of neutron-rich beams at REX-ISOLDE
After the successful commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) -an accelerator for exotic nuclei produced by ISOLDE- in 2002 and the promotion to a CERN user facility in 2003, first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results on the neutron-rich Na and Mg isotopes show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium γ spectrometer MINIBALL. (orig.)
Study of the Neutron-rich Isotope Ar-46 Through Intermediate Energy Coulomb Excitation
Calinescu, S.; Ceceres, L.; Grévy, S.; Sorlin, O.; Sohler, D.; Stanoiu, M.; Negoita, F.; Clement, E.; Astabatyan, R.; Borcea, C.; Borcea, R.; Bowry, M.; Catford, W.; Dombradi, Z.; Franchoo, S.; Garcia, R.; Gillibert, R.; Guerin, H.; Thomas, J. C.; Kuti, I.; Lukyanov, S.; Lepailleur, A.; Maslov, V.; Morfouace, P.; Mrázek, Jaromír; Niikura, M.; Perrot, L.; Podolyak, Z.; Petrone, C.; Peniozhkevich, Y.; Roger, T.; Rotaru, F.; Stefan, I.; Vajta, Zs.; Wilson, E.
2014-01-01
Roč. 45, č. 2 (2014), s. 199-204. ISSN 0587-4254 Institutional support: RVO:61389005 Keywords : GANIL * detector Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.850, year: 2014
Study of low-lying excitations in 110Pd
High resolution inelastic scattering measurements with 20 MeV polarized deuterons and results of recent Coulomb excitation studies of Hasselgren et al. on 110Pd are compared with predictions from new IBA calculations, where configuration mixing or QQ interaction between like bosons was included to describe intruder states and triaxial features, respectively. The spectroscopic properties of the four low-energy collective bands are well described. (orig.)
Coulomb effects in relativistic laser-assisted Mott scattering
We reconsider the influence of the Coulomb interaction on the process of relativistic Mott scattering in a powerful electromagnetic plane wave for which the ponderomotive energy is of the order of the magnitude of the electron's rest mass. Coulomb effects of the bare nucleus on the laser-dressed electron are treated more completely than in the previous work of Li et al. [J. Phys. B: At. Mol. Opt. Phys. 37 (2004) 653]. To this end we use Coulomb-Dirac-Volkov functions to describe the initial and the final states of the electron. First-order Born differential cross sections of induced and inverse bremsstrahlung are obtained for circularly and linearly polarized laser light. Numerical calculations are carried out from both polarizations, for various nucleus charge values, three angular configurations and an incident energy in the MeV range. It is found that for parameters used in the present work, incorporating Coulomb effects of the target nucleus either in the initial state or in the final state yields cross sections which are quite similar whatever the scattering geometry and polarization considered. When Coulomb distortions are included in both states, the cross sections are strongly modified with the increase of Z, as compared to the outcome of the prior form of the T-matrix treatment. (author)
Coulomb versus physical string tension on the lattice
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.
Study of resonances in 16O, 28Si elastic scattering near the Coulomb barrier
The 28Si + 16O elastic scattering has been studied above the Coulomb barrier. Height angular distributions has been measured and analyzed between 18.67 MeV and 22.29 MeV center of mass energy. An optical model analysis shows that the very deep and transparent potentials reproduce the oscillations at back angles of the angular distributions. This result is confirmed by a coupled equation analysis of the elastic and inelastic scattering of the first 2+ state of 28Si. A semi-classical analysis shows a pole in these very transparent optical potentials. An analysis with only one Regge pole by angular distribution reproduces perfectly the data. An phase shift analysis confirms the presence of resonant quasi-molecular states of short lifetime with overlapping width to explain the first structure observed in the excitation function measured at 1800 in the center of mass. A spin value has been assigned at these resonant states
The diatomic-chain model of mixed-stack molecular crystal is studied accounting for the electron correlation and lattice relaxation. Energetics, Peierls distorsion and charge transfer are calculated by the use of optimized-germinal technique. The realistic case of Hubbard electron repulsion on donors stronger than on acceptors is considered, it is shown that taking into account this difference improves the predictions of dimerization properties. The limiting case of correlated donor-acceptor dimers that interact only through Coulomb field is considered analytically; it is found that interdimer hopping is essential for adequate predictions of characteristics of neutral-to-ionic phase transition. Calculations of broken-symmetry states of the correlated chain show that metastable solitons with excitation energy close to transfer integral are possible near the phase transition point
Muonic molecules as three-body Coulomb problem in adiabatic approximation
The three-body Coulomb problem is treated within the framework of the hyperspherical adiabatic approach. The surface functions are expanded into Faddeev-type components in order to ensure the equivalent representation of all possible two-body contributions. It is shown that this decomposition reduces the numerical effort considerably. The remaining radial equations are solved both in the extreme and the uncoupled adiabatic approximation to determine the binding energies of the systems (dtμ) and (d3Heμ). Whereas the ground state is described very well in the uncoupled adiabatic approximation, the excited states should be treated within the coupled adiabatic approximation to obtain good agreement with variational calculations. (orig.)
Strong enhancement of cage effects in water photolysis caused by interatomic Coulombic decay.
Jabbari, Ghazal; Sadri, Keyvan; Cederbaum, Lorenz S; Gokhberg, Kirill
2016-04-28
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 Ã excited state is strongly quenched by ICD. We found that this very efficient quenching is due to two factors. First, the lifetimes of the Ã 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. PMID:27131550
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.
Karan Singh Vinayak; Suneel Kumar
2014-03-01
Within the framework of isospin-dependent quantum molecular dynamics (IQMD) model, we demonstrate the evolution of intermediate mass fragments in heavy-ion collisions. In this paper, we study the time evolution, impact parameter, and excitation energy dependence of IMF production for the different forms of density-dependent symmetry energy. The IMF production and charge distribution show a minor but considerable sensitivity towards various forms of densitydependent symmetry energy. The Coulomb interactions affect the IMF production significantly at peripheral collisions. The IMF production increases with the stiffness of symmetry energy.
Coulomb crystal mass spectrometry in a digital ion trap
Deb, Nabanita; Smith, Alexander D; Keller, Matthias; Rennick, Christopher J; Heazlewood, Brianna R; Softley, Timothy P
2015-01-01
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 radiofrequency waveform is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields subsequently applied to the trap electrodes for ion ejection. Excellent detection efficiency is demonstrated for Ca+ and CaF+ ions from bi-component Ca+/CaF+ Coulomb crystals prepared by reaction of Ca+ with CH3F. A quantitative linear relationship is observed between ion number and the corresponding integrated TOF peak, independent of the ionic species. The technique is applicable to a diverse range of multi-component Coulomb crystals - demonstrated here for Ca+/NH3+/NH4+ and Ca+/CaOH+/CaOD+ crystals - and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.
CubeSat testing of Coulomb drag propulsion
Janhunen, Pekka; Toivanen, Petri; Rauhala, Timo; Haeggström, Edward; Grönland, Tor-Arne
2016-01-01
In Coulomb drag propulsion, a long high voltage tether or system of tethers gathers momentum from a natural plasma stream such as solar wind or ionospheric plasma ram flow. A positively polarised tether in the solar wind can be used for efficient general-purpose interplanetary propellantless propulsion (the electric solar wind sail or E-sail), whereas a negatively polarised tether in LEO can be used for efficient deorbiting of satellites (the plasma brake). Aalto-1 is a 3-U cubesat to be launched in May 2016. The satellite carries three scientific experiments including 100 m long Coulomb drag tether experiment. The tether is made of four 25 and 50 micrometre diameter aluminium wires that are ultrasonically bonded together every few centimetre intervals. The tether can be charged by an onboard voltage source up to one kilovolt positive and negative. The Coulomb drag is measured by monitoring the spin rate.
Adiabatic and non-adiabatic processes in strong Coulomb fields
Adiabatic and non-adiabatic behaviour of relativistic electrons in external Coulomb fields of time-dependent strength is studied within the framework of a model for the description of a shell electron's behaviour during a heavy-ion collision. A classification scheme for types of non-adiabatic behaviour is suggested; its relevance for the analysis of pair production processes in strong Coulomb fields is discussed (K-Shell Ionization). An ansatz for the vacuum polarization potential is introduced and employed to demonstrate the special role of vacuum polarization for adiabatic and non-adiabatic behaviour in very strong Coulomb fields (Zα > 1). The implications of the underlaying specific features of the vacuum polarization charge density in very strong fields for pair production mechanisms are considered. (orig.)
Gribov horizon and Gribov copies effect in lattice Coulomb gauge
Burgio, Giuseppe; Reinhardt, Hugo; Vogt, Hannes
2016-01-01
Following a recent proposal by Cooper and Zwanziger we investigate via lattice simulations the effect on the Coulomb gauge propagators and on the Gribov-Zwanziger confinement mechanism of selecting the Gribov copy with the smallest non-trivial eigenvalue of the Faddeev-Popov operator, i.e. the one closest to the Gribov horizon. Although such choice of gauge drives the ghost propagator towards the prediction of continuum calculations, we find that it actually overshoots the goal. With increasing computer time, we observe that Gribov copies with arbitrarily small eigenvalues can be found. For such a method to work one would therefore need further restrictions on the gauge condition to isolate the physically relevant copies, since e.g. the Coulomb potential $V_C$ defined through the Faddeev-Popov operator becomes otherwise physically meaningless. Interestingly, the Coulomb potential alternatively defined through temporal link correlators is only marginally affected by the smallness of the eigenvalues.
Imaging quantum Hall Coulomb islands inside a quantum ring
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.
Quark Coulomb Interactions and the Mass Difference of Mirror Nuclei
Horowitz, C J
2001-01-01
We study the Okamoto-Nolen-Schiffer (ONS) anomaly in the binding energy of mirror nuclei at high density by adding a single neutron or proton to a quark gluon plasma. In this high-density limit we find an anomaly equal to two-thirds of the Coulomb exchange energy of a proton. This effect is dominated by quark electromagnetic interactions---rather than by the up-down quark mass difference. At normal density we calculate the Coulomb energy of neutron matter using a string-flip quark model. We find a nonzero Coulomb energy because of the neutron's charged constituents. This effect could make a significant contribution to the ONS anomaly.
Weak interaction rate Coulomb corrections in big bang nucleosynthesis
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 ∼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.
Observation of ionic Coulomb blockade in nanopores.
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
Lyapunov spectra of Coulombic and gravitational periodic systems
Kumar, Pankaj
2016-01-01
We compute Lyapunov spectra for Coulombic and gravitational versions of the one-dimensional systems of parallel sheets with periodic boundary conditions. Exact time evolution of tangent-space vectors are derived and are utilized toward computing Lypaunov characteristic exponents using an event-driven algorithm. The results indicate that the energy dependence of the largest Lyapunov exponent emulates that of Kolmogorov-entropy density for each system at different degrees of freedom. Our approach forms an effective and approximation-free tool toward studying the dynamical properties exhibited by the Coulombic and gravitational systems and finds applications in investigating indications of thermodynamic transitions in large versions of the spatially periodic systems.
Coulomb explosion in aromatic molecules and their deuterated derivatives
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.
Nonlinear conductivity of two-dimensional Coulomb glasses
Caravaca, M.; Somoza, A. M.; Ortuño, M.
2011-01-01
We have studied the nonlinear conductivity of two-dimensional Coulomb glasses. We have used a Monte Carlo algorithm to simulate the dynamic of the system under an applied electric field $E$. We found that in the nonlinear regime the site occupancy in the Coulomb gap follows a Fermi-Dirac distribution with an effective temperature $T_{\\rm eff}$, higher than the phonon bath temperature $T$. The value of the effective temperature is compatible with that obtained for slow modes from the generaliz...
Geometrically-frustrated pseudogap phase of Coulomb liquids
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 αc in any dimension d≥2, reflecting the strong geometric frustration produced by long-range interactions. A nearly frozen Coulomb 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.
Convergence of Feynman integrals in Coulomb gauge QCD
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
Strong Coulomb effects in hole-doped Heisenberg chains
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.
Parity Violating Elastic Electron Scattering and Coulomb Distortions
Horowitz, C J
1998-01-01
Parity violating elastic electron-nucleus scattering provides an accurate and model independent measurement of neutron densities, because the $Z^0$ couples primarily to neutrons. Coulomb distortion corrections to the parity violating asymmetry $A_l$ are calculated exactly using a relativistic optical model. Distortions significantly reduce $A_l$ in a heavy nucleus. However even with distortions, an experiment to measure the neutron radius is feasible. This will aid the interpretation of future atomic parity violation measurements and provide fundamental nuclear structure information. Coulomb distortions and small differences between neutron and proton radii could be important for a standard model test on $^4$He, $^{12}$C or $^{16}$O.
The effect of Coulombic friction on spatial displacement statistics
Menzel, Andreas M
2010-01-01
The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. These results are relevant to recent experimental studies of the displacement of colloidal particles along bilayer membrane tubes.
The Coulomb integrals and the diffraction model of transfer reactions
New asymptotic expressions for the Coulomb integrals are derived and compared with numerical results, the Watson asymptotics and the WKB approximations. The analytical expressions for the Coulomb integrals are used in cross section calculations for single-nucleon transfer reactions in the framework of the diffraction model. The case of the zero orbital angular momentum transfer is considered. The interference of the Fresnel and Fraunhofer parts of the reaction amplitude are discused in detail. The undertaken treatment can be useful for the interpretation of the associated experimental data and the results of DWBA calculations. (orig.)
Coulomb Blockade in an Ultrathin Ti Nanowire at Room Temperature
CAIQiyu; YANGTao; CAIBingchu; YINYou; JIANGJianfei
2003-01-01
A scanning tunneling microscope operated in ambient air was employed to fabricate a～ 30nm-wide and ～ 700nm-long Ti nanowire connecting the source and drain electrodes on a 3nm-thick Ti film. The ultraflne but nonuniform Ti nanowire was well defined between two ox-idized lines. The gate electrode was capacitively coupled to the nanowire by a ～150nm-wide oxidized line. The electrical properties measured at room temperature of the Ti nanowire showed Coulomb blockade in highly nonlinear Ids-Vds characteristics and Coulomb oscillation in Ids - Vgs characteristics.
Renormalization of Optical Excitations in Molecules near a Metal Surface
García Lastra, Juan Maria; Thygesen, Kristian Sommer
2011-01-01
consequence we find that close to the metal surface the optical gap of benzene can exceed its quasiparticle gap. A classical image charge model for the screened Coulomb interaction can account for all these effects which, on the other hand, are completely missed by standard time-dependent density functional......The lowest electronic excitations of benzene and a set of donor-acceptor molecular complexes are calculated for the gas phase and on the Al(111) surface using the many-body Bethe-Salpeter equation. The energy of the charge-transfer excitations obtained for the gas phase complexes are found to be...
A non-variational approach to the quantum three-body Coulomb problem
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
Effect of coulomb interaction on Anderson localization
We study the quantum mechanics of interacting particles in a disordered system, and in particular, what happens to Anderson localisation when interaction is taken into account. In the first part, one looks at the excited states of two particles in one dimension. For this model, it has been shown (Shepelyansky 1994) that a local repulsive interaction can partially destroy Anderson localisation. Here, we show that this model has similarities with the three-dimensional Anderson model at the metal-insulator transition. In particular, the maximum of rigidity obtained in the spectral statistics correspond to some intermediary statistics that cannot be described by random matrix theory neither by a Poisson statistics. The wave functions show a multifractal behaviour and the spreading of the center of mass of a wave packet is logarithmic in time. The second part deals with the ground state of a finite density of spinless fermions in two dimensions. After the scaling theory of localisation, it was commonly accepted that there was no metal in two dimensions. This idea has been challenged by the observation of a metal-insulator transition in low density electron gas (Kravchenko et al. 1994). We propose a scenario in which a metallic phase occurs between the Anderson insulator and the pinned Wigner crystal. This intermediate phase is characterized by an alignment of the local currents flowing in the system. (author)
Jönsson, B; Söderberg, B
1993-01-01
A variational approach is used to calculate free energy and conformational properties in polyelectrolytes. The true bond and Coulomb potentials are approximated by a trial isotropic harmonic energy containing monomer-monomer force constants as variational parameters. By a judicious choice of representation and the use of incremental matrix inversion, an efficient and fast-convergent iterative algorithm is constructed, that optimizes the free energy. The computational demand scales as N^3. The method has the additional advantage that the entropy is easily computed. An analysis of the high and low temperature limits is given. Also, the variational formulation is shown to respect the appropriate virial identities. The accuracy of the approximations introduced are tested against Monte Carlo simulations for problem sizes ranging from N=20 to 1024. Very good performance is obtained for chains with unscreened Coulomb interactions. The addition of salt is described through a screened Coulomb interaction, for which th...
Mauser, Christian
2011-02-03
charge carriers were additionally studied at high excitation energies. An efficient multi-exciton emission of the CdSe/CdS tetrapods could be observed, which is to be lead back to the exciton phase-space filling and a reduced Auger effect. The larger volume of the longer tetrapods allows a dual emission from the CdSe and the CdS with comparable intensities. The occuring Coulomb effects between a spatially separated electron-hole pair were studied in CdSe/CdTe tetrapods, which exhibit a type-II transition. A correlation between the tetrapod leg length and the binding energy of the charge-transfer exciton could be established, which is also reproduced in the theoretical simulations.
Core excitation effects in halo nuclei using a transformed oscillator basis
A recent generalization of the Transformed Harmonic Oscillator basis, intended to consider core excitations in the structure of one nucleon halo nuclei, is applied to the break up of 11Be. The reaction studied is 11Be+208Pb at 69 MeV/nucleon. The experimental set up is designed to ensure pure dipole Coulomb excitations. Making use of the Equivalent Photon Method and the electromagnetic transition probabilities obtained with the transformed oscillator basis, a relevant contribution of the quadrupole excitations of the core is found. The inclusion of core excitations is, therefore, necessary for the correct extraction of the dipole electromagnetic transition probability of halo nuclei.
Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study
Lunde, Anders Mathias; Flensborg, Karsten; Jauho, Antti-Pekka
2005-01-01
We calculate the intershell resistance R-21 in a multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F) (e.g., a gate voltage), varying the chirality of the inner and outer tubes. This is done in a so-called Coulomb drag setup, where a current I-1 in one shell induces a...
Algebraization of elliptic Coulomb wave functions in the continuous spectrum
Trinomial recurrent relations specifying in the continuous spectrum decomposition of elliptical Coulomb wave functions by polar basis of two-dimensional hydrogen atoms are found. This algebraization is suitable for development of the perturbation theory when calculating elliptical corrections to the polar basis
Propagator for an Aharonov-Bohm-Coulomb system
Park, D. K.; Yoo, Sahng-Kyoon; Lee, Soo-Young; Kahng, Jae-Rok; Park, Chang Soo; Yim, Eui-Soon; Lee, C.H.
1997-01-01
The propagator of three-dimensional Aharonov-Bohm-Coulomb system is calculated by following the Duru-Kleinert method. It is shown that the system is reduced to two independent two dimensional Aharonov-Bohm plus harmonic oscillator systems through dimensional extension and Kustaanheimo-Stiefel transformation. The energy spectrum is deduced.
Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians
Avery, James Emil
hyperspherical harmonics. A rudimentary software library has been implemented and preliminary benchmarks indicate very good performance: On average 40 ns, or approximately 80 clock cycles, per electron repulsion integral. This makes molecular Coulomb Sturmians competitive with Gaussian type orbitals in terms of...
Chaos in a coulombic muffin-tin potential
We study the two-dimensional classical scattering dynamics by a Muffin-Tin potential with 3 Coulomb singularities. A complete symbolic dynamics for the periodic orbits is derivd. The classical trajectories are shown to be hyperbolic everywhere in phase space and to carry no conjugate points. (orig.)
Coulomb displacement energies between analog levels for 44 < = A < = 239
Experimental Coulomb displacement energie ΔEsub(C) between isobaric analog levels are tabulated for 44 <- A <- 239, extending recent work in which similar data were presented for 3 <- A <- 45. An overall parametrization in anti-Z/A sup(1/3) and uniform radius parameters rsub(o) are given
Analytic structure of many-body Coulombic wave functions
Fournais, Søren; Hoffmann-Ostenhof, Maria; Hoffmann-Ostenhof, Thomas; Sørensen, Thomas Østergaard
2009-01-01
We investigate the analytic structure of solutions of non-relativistic Schrödinger equations describing Coulombic many-particle systems. We prove the following: Let ψ(x) with denote an N-electron wavefunction of such a system with one nucleus fixed at the origin. Then in a neighbourhood of a...
Limits to Electron Beam Emittance from Stochastic Coulomb Interactions
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.
Existence of the thermodynamic limit for disordered quantum Coulomb systems
Blanc, Xavier
2012-01-01
Following a recent method introduced by C. Hainzl, J.P. Solovej and the second author of this article, we prove the existence of the thermodynamic limit for a system made of quantum electrons, and classical nuclei whose positions and charges are randomly perturbed in an ergodic fashion. All the particles interact through Coulomb forces.
Exchange Coulomb interaction in nanotubes: Dispersion of Langmuir waves
The microscopic derivation of the Coulomb exchange interaction for electrons located on the nanotubes is presented. The derivation is based on the many-particle quantum hydrodynamic method. We demonstrate the effect of curvature of the nanocylinders on the force of exchange interaction. We calculate corresponding dispersion dependencies for electron oscillations on the nanotubes
Revised variational approach to QCD in Coulomb gauge
Campagnari, Davide R; Reinhardt, Hugo; Vastag, Peter
2016-01-01
The variational approach to QCD in Coulomb gauge is revisited. By assuming the non-Abelian Coulomb potential to be given by the sum of its infrared and ultraviolet parts, i.e.~by a linearly rising potential and an ordinary Coulomb potential, and by using a Slater determinant ansatz for the quark wave functional, which contains the coupling of the quarks and the gluons with two different Dirac structures, we obtain variational equations for the kernels of the fermionic vacuum wave functional, which are free of ultraviolet divergences. Thereby, a Gaussian type wave functional is assumed for the gluonic part of the vacuum. By using the results of the pure Yang--Mills sector for the gluon propagator as input, we solve the equations for the fermionic kernels numerically and calculate the quark condensate and the effective quark mass in leading order. Assuming a value of $\\sigma_{\\mathrm{C}} = 2.5 \\sigma$ for the Coulomb string tension (where $\\sigma$ is the usual Wilsonian string tension) the phenomenological valu...
Plasmon-mediated Coulomb drag between graphene waveguides
Shylau, Artsem A.; Jauho, Antti-Pekka
2014-01-01
We analyze theoretically charge transport in Coulomb coupled graphene waveguides (GWGs). The GWGs are defined using antidot lattices, and the lateral geometry bypasses many technological challenges of earlier designs. The drag resistivity ρD, which is a measure of the many-particle interactions...
Limits to Electron Beam Emittance from Stochastic Coulomb Interactions
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.
Coulomb potential from a particle in uniform ultrarelativistic motion
Baltz, A. J.
1995-01-01
The Coulomb potential produced by an ultrarelativistic particle (such as a heavy ion) in uniform motion is shown in the appropriate gauge to factorize into a longitudinal Dirac delta function of (z - t) times the simple two dimensional potential solution in the transverse direction. This form makes manifest the source of the energy independence of the interaction.
Finiteness of the Coulomb gauge QCD perturbative effective action
Andraši, A., E-mail: aandrasi@irb.hr [Vlaška 58, Zagreb (Croatia); Taylor, J.C., E-mail: jct@damtp.cam.ac.uk [DAMTP, University of Cambridge, Cambridge (United Kingdom)
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.
Finiteness of the Coulomb gauge QCD perturbative effective action
Andrasi, A
2015-01-01
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.
Molecular integrals for slater type orbitals using coulomb sturmians
Avery, James Emil; Avery, John Scales
2014-01-01
The use of Slater type orbitals in molecular calculations is hindered by the slowness of integral evaluation. In the present paper, we introduce a method for overcoming this problem by expanding STO's in terms of Coulomb Sturmians, for which the problem of evaluating molecular integrals rapidly has...
Hester, Tim; Maglich, Bogdan; Calsec Collaboration
2015-10-01
Copious T and 3He production from D(d, p) T and D(d, n) 3He reactions in 725 KeV colliding beams was observed in weak-focusing Self-Collider1-4 radius 15 cm, in B = 3.12 T, stabilized5 non-linearly by electron cloud oscillations with confinement time ~ 23 s. BARC's simulations7 predict that by switching to Strong Focusing Self Collider proposed by Blewett6, 10 deuterons 0.75 MeV each, will generate 1 3He + 1T +1p + 1n at a total input energy cost of 10.72 MeV. Economic value of T and 3He is 65 and 120 MeV/atom respectively. While energy balance is negative, we project economic gain 205 MeV/10.72 MeV ~ 20 i.e. 3He production/sale will fund cost of T. Assuming the luminosity achieved in MIGMA IV, we replace D beam injection with a high energy beam of 14 times ionized natural Mo ions and look for the 1-neutron reactions of the type 98Mo+100Mo -->299Mo, where 99Mo14+ will be EM channeled into a mass spectrometer and collected at one loci/ radius, while all other masses/radii rejected. Physics and engineering parameters required to produce at least 1 g of 99Mo per day, at an electricity cost of 100K, will be presented. 2- and 3-neutron exchange reactions will be considered, too.
A Note on AdS/SYM Correspondence on the Coulomb Branch
Wu, Yi-Yen
1998-01-01
We study Maldacena's conjecture and the AdS/SYM correspondence on the Coulomb branch. Several interesting aspects of this conjectured AdS/SYM correspondence on the Coulomb branch are pointed out and clarified.
Concepts of Highly Excited Electronic Systems
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
Proton excitations across the Z=64 gap in the doubly magic superdeformed nucleus 144Gd
Five superdeformed (SD) bands have been identified in 144Gd with the GASP array using the reaction 100Mo+48Ti. The J(2) moments of inertia of the four excited SD bands are flat as a function of rotational frequency, indicating the blocking of the N=6 proton crossing observed in the yrast SD band. According to cranked shell model calculations, the excited bands have two-quasiproton configurations with one proton in the N=6 orbital and the other in each signature partner of the [404[9/2+ or [411[3/2+ orbitals, lying above the Z=64 gap. The interpretation of the excited SD bands in terms of proton excitations points to the high stability of the N=80 shell closure at SD shapes. The population of the yrast SD band as a function of the beam energy has been also investigated. Our data shows that the intensity of the yrast SD band is not configuration dependent, being comparable to that of yrast SD bands in the neighboring nuclei. By comparing experimental and theoretical alignments, spins and configurations are assigned to all observed SD bands in the A=140-150 region. (orig.)
Third order Bose-Einstein correlations by means of Coulomb wave function revisited
Biyajima, Minoru; Mizoguchi, Takuya; Suzuki, Naomichi
2005-01-01
In previous works, in order to include correction by the Coulomb wave function in Bose-Einstein correlations (BEC), the two-body Coulomb scattering wave functions have been utilized in the formulation of three-body BEC. However, the three-body Coulomb scattering wave function, which satisfies approximately the three-body Coulomb scattering Schrodinger equation, cannot be written by the product of the two-body scattering wave functions. Therefore, we reformulate the three-body BEC, and reanaly...
Coulomb-nucleon phase and spin effects in the diffraction dip domain
The total phase of the Coulomb-hadron interaction is calculated with the true hadron scattering amplitude and with the Coulomb amplitude including the form factor of hadrons. This phase includes also the contribution of the phase of the pure coulomb interaction of hadrons taking into account the hadron form factors. The analyzing power AN is calculated in the whole diffraction dip domain of high-energy elastic hadron scattering with the Coulomb-hadron interference effects. (author)
Coulomb correction to the parameters of the Landau-Pomeranchuk-Migdal effect theory
Using the Coulomb correction to the screening angular parameter of the Moliere 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 completely eliminating the discrepancy between the predictions of the LPM effect theory and its measurements
On the role of deformed Coulomb potential in fusion using energy density formalism
Lavneet Kaur; Raj Kumari
2015-10-01
Using the Skyrme energy density formalism, the effect of deformed Coulomb potential on fusion barriers and fusion cross-sections is studied. Our detailed study reveals that the fusion barriers as well as fusion probabilities depend on the shape deformation (due to deformed Coulomb potential) of the colliding nuclei. However, this dependence due to deformed Coulomb potential is found to be very weak.
Mohr, Peter
2016-01-01
In their recent study Neelam, Shubhchintak, and Chatterjee have claimed that "it would certainly be useful to perform a Coulomb dissociation experiment to find the low energy capture cross section for the reaction" $^{15}$N(n,$\\gamma$)$^{16}$N. However, it is obvious that a Coulomb dissociation experiment cannot constrain this capture cross section because the dominating branchings of the capture reaction lead to excited states in $^{16}$N which do not contribute in a Coulomb dissociation experiment. An estimate of the total $^{15}$N(n,$\\gamma$)$^{16}$N cross section from Coulomb dissociation of $^{16}$N requires a precise knowledge of the $\\gamma$-ray branchings in the capture reaction. Surprisingly, the calculation of Neelam, Shubhchintak, and Chatterjee predicts a strongly energy-dependent ground state branching of the order of 0.05\\% to 0.6\\% at energies between 100 and 500 keV which is almost 2 orders of magnitude below calculations in the direct capture model. Additionally, this calculation of Neelam, S...
Fusion and direct reactions around the Coulomb barrier with the neutron-rich 8He
Radioactive ion beams like 8He, open new possibilities to investigate the influence of new and exotic structures on reaction mechanisms. This thesis presents the first investigations of reactions of the weakly bound, Borromean nucleus, 8He, at energies around the Coulomb barrier. The low intensity of radioactive ion beams (∼ 105 pps) necessitated the development of a new sensitive and selective technique for the precise and accurate measurement of fusion cross sections. In the 8He+197Au system, excitation functions for fusion and neutron(s) transfer were measured. In the 8He+65Cu system, differential and integral cross sections for various processes like elastic scattering, neutron transfer and fusion were measured using both, inclusive and exclusive measurements of characteristic γ-rays, charged particles and neutrons. These experimental results combined with coupled reaction channels calculations demonstrated the inter-connectivity among the various reaction processes. The internal structure of 8He influenced the tunneling process and neutron(s) transfer and interestingly, revealed an unexpected behavior within the Helium isotopic chain. Further, a systematic analysis of the known fusion excitation functions showed that the increase in sub-barrier fusion cross sections associated with the internal structure of nuclei, is in fact much larger for 'normal' nuclei than for light, weakly-bound 'exotic' nuclei. (author)
Modeling anisotropic plasmon excitations in self-assembled fullerenes
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.
Gravity duals for the Coulomb branch of marginally deformed Script N = 4 Yang-Mills
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.
Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons
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.
Reconfiguration and Control of Non-Equal Mass Three-Craft Coulomb Formation
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.
Coulomb-Born-Oppenheimer approximation in Ps-H scattering
Hasi Ray
2006-02-01
To improve the Coulomb-Born approximation (CBA) theory of ionization in positronium (Ps) and atom scattering, the effect of exchange is introduced. The nine-dimensional exchange amplitude for ionization of Ps in Ps-H scattering is reduced to a two-dimensional integral using the present Coulomb-Born-Oppenheimer approximation (CBOA). The methodology is extremely useful to evaluate ionization parameters for different target systems and for different types of ionization processes. It is then applied to evaluate the Ps-ionization cross-section and to estimate the effect of exchange on Ps-ionization in Ps-H system. We establish the importance of exchange at lower energy region.
Coulomb effects in low-energy nuclear fragmentation
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.
Molecular Ion Geometries from Inversion of Coulomb Explosion Imaging Data
The inversion of Coulomb explosion imaging (CEI) data is made possible by means of a scheme termed the modified backward integration (MBI) method. This method allows one to analyze CEI data for a single Coulomb explosion event so as to infer the geometry of the relevant molecule or molecular ion. We outline the MBI scheme whose two key features are the use of a hyperspherical coordinate system and the change of the independent variable from time to the hyper-radial coordinate. We also test the method on simulated open-quote open-quote experimental close-quote close-quote data for idealized model species of known geometry, and then apply it to CEI data actually measured. copyright 1996 The American Physical Society
An infinite family of superintegrable deformations of the Coulomb potential
Post, Sarah [Centre de recherches mathematiques, CP 6128 succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada); Winternitz, Pavel, E-mail: post@CRM.UMontreal.C, E-mail: wintern@CRM.UMontreal.C [Centre de recherches mathematiques and Departement de mathematiques et de statistique, CP 6128 succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada)
2010-06-04
We introduce a new family of Hamiltonians with a deformed Kepler-Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wavefunctions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wavefunctions, and give the transformed integrals explicitly for the classical system. (fast track communication)
An infinite family of superintegrable deformations of the Coulomb potential
Post, S
2010-01-01
We introduce a new family of Hamiltonians with a deformed Kepler- Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wave functions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wave functions and give the transformed integrals explicitly for the classical system.
An infinite family of superintegrable deformations of the Coulomb potential
We introduce a new family of Hamiltonians with a deformed Kepler-Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wavefunctions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wavefunctions, and give the transformed integrals explicitly for the classical system. (fast track communication)
Hadron diffractive scattering at ultrahigh energies and coulomb interaction
Anisovich, V V
2016-01-01
We study the interplay of hadronic and Coulomb interactions for $pp$ scattering at LHC energies on the basis of the previous determination of the real part of the amplitude [{\\it V.V. Anisovich, V.A. Nikonov, J. Nyiri}, Int. J. Mod. Phys. A{\\bf 30}, 1550188 (2015)]. The interference of hadron and Coulomb interactions is discussed in terms of the $K$-matrix function technique. Supposing the black disk mode for the asymptotic interaction of hadrons, we calculate interference effects for the energies right up to $\\sqrt{s}= 10^6$ TeV. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk that results in a growth of interplay effects with the energy increase.
Coulomb and nuclear breakup at low energies: Scaling laws
We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei. (authors)
A Coulomb collision algorithm for weighted particle simulations
Miller, Ronald H.; Combi, Michael R.
1994-01-01
A binary Coulomb collision algorithm is developed for weighted particle simulations employing Monte Carlo techniques. Charged particles within a given spatial grid cell are pair-wise scattered, explicitly conserving momentum and implicitly conserving energy. A similar algorithm developed by Takizuka and Abe (1977) conserves momentum and energy provided the particles are unweighted (each particle representing equal fractions of the total particle density). If applied as is to simulations incorporating weighted particles, the plasma temperatures equilibrate to an incorrect temperature, as compared to theory. Using the appropriate pairing statistics, a Coulomb collision algorithm is developed for weighted particles. The algorithm conserves energy and momentum and produces the appropriate relaxation time scales as compared to theoretical predictions. Such an algorithm is necessary for future work studying self-consistent multi-species kinetic transport.
Stationary entanglement between two nanomechanical oscillators induced by Coulomb interaction
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).
Cooling of cryogenic electron bilayers via the Coulomb interaction
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.
Structural phase transitions and topological defects in ion Coulomb crystals
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 nonadiabatically. 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
Low-Temperature Kinetics and Dynamics with Coulomb Crystals
Heazlewood, Brianna R.; Softley, Timothy P.
2015-04-01
Coulomb crystals-as a source of translationally cold, highly localized ions-are being increasingly utilized in the investigation of ion-molecule reaction dynamics in the cold regime. To develop a fundamental understanding of ion-molecule reactions, and to challenge existing models that describe the rates, product branching ratios, and temperature dependence of such processes, investigators need to exercise full control over the experimental reaction parameters. This requires not only state selection of the reactants, but also control over the collision process (e.g., the collisional energy and angular momentum) and state-selective product detection. The combination of Coulomb crystals in ion traps with cold neutral-molecule sources is enabling the measurement of state-selective reaction rates in a diverse range of systems. With the development of appropriate product detection techniques, we are moving toward the ultimate goal of examining low-energy, state-to-state ion-molecule reaction dynamics.
Characterization of ion Coulomb crystals for fundamental sciences
Okada, Kunihiro, E-mail: okada-k@sophia.ac.jp [Sophia University, Department of Physics (Japan); Ichikawa, Masanari [RIKEN Nishina Center for Accelerator-Based Science (Japan); Wada, Michiharu, E-mail: mw@riken.go.jp [Sophia University, Department of Physics (Japan)
2015-11-15
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 {sup 165}Ho{sup 14+} ions in small linear ion Coulomb crystals. The present results show that sub-milli-Kelvin temperatures of at least 10 Ho{sup 14+} ions will be achieved by sympathetic cooling with a single laser-cooled Be{sup +}.
Renormalization group analysis of graphene with a supercritical Coulomb impurity
Nishida, Yusuke
2016-01-01
We develop a field theoretical approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov-Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.
Structural phase transitions and topological defects in ion Coulomb crystals
Partner, Heather L. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Nigmatullin, Ramil [Institute of Quantum Physics, Albert-Einstein Allee-11, Ulm University, 89069 Ulm (Germany); Burgermeister, Tobias; Keller, Jonas; Pyka, Karsten [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany); Plenio, Martin B. [Center for Integrated Quantum Science and Technology, Albert-Einstein-Allee 11, Ulm University, 89069 Ulm (Germany); Institute for Theoretical Physics, Albert-Einstein-Allee 11, Ulm University, 89069 Ulm (Germany); Retzker, Alex [Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Givat Ram (Israel); Zurek, Wojciech H. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Campo, Adolfo del [Department of Physics, University of Massachusetts Boston, Boston, MA 02125 (United States); Mehlstäubler, Tanja E., E-mail: tanja.mehlstaeubler@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)
2015-03-01
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 nonadiabatically. 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.
Coulomb field of an accelerated charge physical and mathematical aspects
Alexander, F J; Alexander, Francis J.; Gerlach, Ulrich H.
1991-01-01
The Maxwell field equations relative to a uniformly accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge invariant potentials. They refer to the transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge invariant "2+2" decomposition is used to see how the Coulomb field of a charge, static in an accelerated frame, has properties that suggest features of electromagnetism which are different from those in an inertial frame. In particular, (1) an illustrative calculation shows that the Larmor radiation reaction equals the electrostatic attraction between the accelerated charge and the charge induced on the surface whose history is the event horizon, and (2) a spectral decomposition of the Coulomb potential in the accelerated frame suggests the possibility that the distortive effects of this charge on the Rindler vacuum are akin to those of a charge on a crystal lattice.
Structural phase transitions and topological defects in ion Coulomb crystals
Partner, Heather L. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Nigmatullin, Ramil [Institute of Quantum Physics, Ulm Univ., Ulm (Germany); Burgermeister, Tobias [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Keller, Jonas [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Pyka, Karsten [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Plenio, Martin B. [Center for Integrated Quantum Science and Technology, Ulm Univ., Ulm, (Germany):Institute for Theoretical Physics, Ulm Univ.,Ulm, (Germany); Retzker, Alex [Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram (Israel); Zurek, Wojciech Hubert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); del Campo, Adolfo [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Physics; Mehlstaubler, Tanja E. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)
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.
Scaling laws for near barrier Coulomb and Nuclear Breakup
Hussein, M S; Lubian, J; Otomar, D R; Canto, L F
2013-01-01
We investigate the nuclear and the Coulomb contributions to the breakup cross sections of $^6$Li in collisions with targets in different mass ranges. Comparing cross sections for different targets at collision energies corresponding to the same $E/V_{\\mathrm{\\scriptscriptstyle B}}$, we obtain interesting scaling laws. First, we derive an approximate linear expression for the nuclear breakup cross section as a function of $A_{\\mathrm{% \\scriptscriptstyle T}}^{1/3}$. We then confirm the validity of this expression performing CDCC calculations. Scaling laws for the Coulomb breakup cross section are also investigated. In this case, our CDCC calculations indicate that this cross section has a linear dependence on the atomic number of the target. This behavior is explained by qualitative arguments. Our findings, which are consistent with previously obtained results for higher energies, are important when planning for experiments involving exotic weakly bound nuclei.
Imaging Coulomb islands in a quantum Hall interferometer.
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
Antiproton-Nucleus Interaction and Coulomb Effect at High Energies
ZHOU Li-Juan; WU Qing; GU Yun-Ting; MA Wei-Xing; TAN Zhen-Qiang; HU Zhao-Hui
2005-01-01
The Coulomb effect in high energy antiproton-nucleus elastic and inelastic scattering from 12C and 16O is studied in the framework of Glauber multiple scattering theory for five kinetic energies ranged from 0.23 to 1.83 GeV.A microscopic shell-model nuclear wave functions, Woods-Saxon single-particle wave functions, and experimental pN amplitudes are used in the calculations. The results show that the Coulomb effect is of paramount importance for filling up the dips of differential cross sections. We claim that the present result for inelastic scattering of antiproton-12C is sufficiently reliable to be a guide for measurements in the very near future. We also believe that antiproton nucleus elastic and inelastic scattering may produce new information on both the nuclear structure and the antinucleon-nucleon interaction, in particular the p-neutron interaction.
Femtosecond Studies Of Coulomb Explosion Utilizing Covariance Mapping
Card, D A
2000-01-01
The studies presented herein elucidate details of the Coulomb explosion event initiated through the interaction of molecular clusters with an intense femtosecond laser beam (≥1 PW/cm2). Clusters studied include ammonia, titanium-hydrocarbon, pyridine, and 7-azaindole. Covariance analysis is presented as a general technique to study the dynamical processes in clusters and to discern whether the fragmentation channels are competitive. Positive covariance determinations identify concerted processes such as the concomitant explosion of protonated cluster ions of asymmetrical size. Anti- covariance mapping is exploited to distinguish competitive reaction channels such as the production of highly charged nitrogen atoms formed at the expense of the protonated members of a cluster ion ensemble. This technique is exemplified in each cluster system studied. Kinetic energy analyses, from experiment and simulation, are presented to fully understand the Coulomb explosion event. A cutoff study strongly suggests that...
Simulation of Coulomb interaction effects in electron sources
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, LaB6 guns and flat dispenser-type cathodes.
Simulation of Coulomb interaction effects in electron sources
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.
Simulation of Coulomb interaction effects in electron sources
Rouse, John, E-mail: john@mebs.co.uk [Munro' s Electron Beam Software Ltd., 14 Cornwall Gardens, London SW7 4AN (United Kingdom); Zhu Xieqing; Liu Haoning; Munro, Eric [Munro' s Electron Beam Software Ltd., 14 Cornwall Gardens, London SW7 4AN (United Kingdom)
2011-07-21
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{sub 6} guns and flat dispenser-type cathodes.
Coulomb branch Hilbert series and Three Dimensional Sicilian Theories
Cremonesi, Stefano; Mekareeya, Noppadol; Zaffaroni, Alberto
2014-01-01
We evaluate the Coulomb branch Hilbert series of mirrors of three dimensional Sicilian theories, which arise from compactifying the $6d$ $(2,0)$ theory with symmetry $G$ on a circle times a Riemann surface with punctures. We obtain our result by gluing together the Hilbert series for building blocks $T_{\\mathbf{\\rho}}(G)$, where $\\mathbf{\\rho}$ is a certain partition related to the dual group of $G$, which we evaluated in a previous paper. The result is expressed in terms of a class of symmetric functions, the Hall-Littlewood polynomials. As expected from mirror symmetry, our results agree at genus zero with the superconformal index prediction for the Higgs branch Hilbert series of the Sicilian theories and extend it to higher genus. In the $A_1$ case at genus zero, we also evaluate the Coulomb branch Hilbert series of the Sicilian theory itself, showing that it only depends on the number of external legs.
Coulomb and Nuclear Breakup at Low Energies: Scaling Laws
Hussein M. S.
2013-12-01
Full Text Available We report on a recent work on the low-energy behavior of the breakup cross section in so far as it has important role in the fusion of weakly bound and halo nuclei at near-barrier energies. We assess the way the nuclear component of this cross section scales with the target mass. In complete accord with previous finding at higher energies we verify that the low energy behavior of the breakup cross section for a given projectile and relative center of mass energy with respect to the Coulomb barrier height scales as the cubic root of the mass number of the target. Surprisingly we find that the Coulomb component of the breakup cross section at these low energies also obeys scaling, but with a linear dependence on the target charge. Our findings are important when planning for experiments involving these exotic nuclei.
Dynamical Coulomb blockade and spin-entangled electrons
Recher, Patrik; Loss, Daniel
2003-01-01
We consider the production of mobile and nonlocal pairwise spin-entangled electrons from tunneling of a BCS-superconductor (SC) to two normal Fermi liquid leads. The necessary mechanism to separate the two electrons coming from the same Cooper pair (spin-singlet) is achieved by coupling the SC to leads with a finite resistance. The resulting dynamical Coulomb blockade effect, which we describe phenomenologically in terms of an electromagnetic environment, is shown to be enhanced for tunneling...
Quantum calculation of Coulomb reorientation and near-barrier fusion
Simenel, Cédric; Bender, Michael; Chomaz, P.; Duguet, Thomas; de France, G.
2006-01-01
6pages, 2 figures. Proceeding of FUSION06 International audience We investigate the role of deformation on the fusion probability around the barrier using the Time-Dependent Hartree-Fock theory with a full Skyrme force. We obtain a distribution of fusion probabilities around the nominal barrier due to the different contributions of the various orientations of the deformed nucleus at the touching point. It is also shown that the long range Coulomb reorientation reduces the fusion probabi...
Suitability of linear quadrupole ion traps for large Coulomb crystals
Tabor, D. A.; Rajagopal, V.; Lin, Y-W.; Odom, B.
2011-01-01
Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial co...
Coulomb interaction and first order superconductor-insulator transition
Syzranov, S. V.; Aleiner, I. L.; Altshuler, B. L.; Efetov, K. B.
2010-01-01
The superconductor-insulator transition (SIT) in regular arrays of Josephson junctions is studied at low temperatures. Near the transition a Ginzburg-Landau type action containing the imaginary time is derived. The new feature of this action is that it contains a gauge field $\\Phi $ describing the Coulomb interaction and changing the standard critical behavior. The solution of renormalization group (RG) equations derived at zero temperature $T=0$ in the space dimensionality $d=3$ shows that t...
Superheavy Elements and Beyond: - Supercritical Coulomb Field and Giant Quasiatoms
The status of theory of Superheavy Nuclei is reviewed. Based with the Two-Center Shell Model Potential Energy Surfaces are calculated. Fusion, fission, quasifission and other processes are discussed. I particular time-delay during the formation of giant quasi atoms/molecules will be crucial for observing the change of the Dirac vacuum in supercritical Coulomb fields by spontaneous positron emission. It will be shown how the various phenomena are interrelated
Three-body processes in the presence of Coulomb forces
Rigorous definitions are provided for the scattering amplitudes describing elastic, inelastic and rearrangement reactions of one charged particle and a bound state of two other charged bodies, and of break-up amplitudes with one neutral and two charged particles. The resulting expressions confirm, and give precise meaning to, what is intuitively anticipated in conventional approaches. Furthermore, integral equations for these transition amplitudes are available which render feasible practical calculations of Coulomb corrections in three-particle reactions. 2 references
Two Approaches to Accelerated Monte Carlo Simulation of Coulomb Collisions
Ricketson, Lee
2014-01-01
In plasma physics, the direct simulation of inter-particle Coulomb collisions is often necessary to capture the relevant physics, but presents a computational bottleneck because of the complexity of the process. In this thesis, we derive, test and discuss two methods for accelerating the simulation of collisions in plasmas in certain scenarios. The first is a hybrid fluid-Monte Carlo scheme that reduces the number of collisions that must be simulated. Coupling between the fluid and particl...
Extended Kepler–Coulomb quantum superintegrable systems in three dimensions
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. (paper)
Leptoproduction of neutrino pairs in the nuclear coulomb field
Pich, Antonio; Bernabéu, José
1985-01-01
[IT] Si calcola la sezione d'urto per la produzione di coppie v-V per leptoni ad alta energia nel campo nucleare di Coulomb nella teoria standard, tenendo conto della polarizzazione arbitraria nel fascio leptonico incidente. Si studiano le distribuzioni differenziali del leptone canco uscente, mostrando che il leptone diffuso forma un picco ad alta energia ed emerge per angoli di un'ampiezza notevole. Si discutono anche i contributi incoerenti alla sezione d'urto.
Coulomb interaction effect in tilted Weyl fermion in two dimensions
Isobe, Hiroki; Nagaosa, Naoto
2015-01-01
Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor $\\alpha$-(BEDT-TTF)$_2$I$_3$ and three-dimensional WTe$_2$. The Coulomb interaction between electrons modifies the velocities in an essential way in the low-energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the...
Identification of Coulomb blockade and macroscopic quantum tunneling by noise
Grabert, Hermann; Ingold, Gert-Ludwig
2002-01-01
The effects of Macroscopic Quantum Tunneling (MQT) and Coulomb Blockade (CB) in Josephson junctions are of considerable significance both for the manifestations of quantum mechanics on the macroscopic scale and potential technological applications. These two complementary effects are shown to be clearly distinguishable from the associated noise spectra. The current noise is determined exactly and a rather sharp crossover between flux noise in the MQT and charge noise in the CB regions is foun...
Imaging Coulomb Islands in a Quantum Hall Interferometer
Hackens, B.; Martins, F.; Faniel, S.; Dutu, C. A.; Sellier, H.; S. Huant; Pala, M; L. Desplanque; 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 that, as edge states come close to each other, electrons can hop between counterpropagating edge channels, or tunnel through Coulomb islands. Here, we ...
Coulomb potential and the paradoxes of PT-symmetrization
Znojil, Miloslav
2012-01-01
Besides the standard quantum version of the Coulomb/Kepler problem, an alternative quantum model with not too dissimilar phenomenological (i.e., spectral and scattering) as well as mathematical (i.e., exact-solvability) properties may be formulated and solved. Several aspects of this model are described. The paper is made self-contained by explaining the underlying innovative quantization strategy which assigns an entirely new role to symmetries.
Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid
Buyukdagli, Sahin; Blossey, Ralf
2013-01-01
We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent generalizing the point-like Dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (J. Phys. Chem 100, 2612 (1996)) and Abrashkin et al. (Phys. Rev. Lett. 99, 077801 (2007)). We formulate a nonlocal Poisson-Boltzmann equation (NLPB) and study both linear and nonlinear dielectric response in this model for the case of a single plane geometry. Our results shed light on the relevanc...
Vacuum polarization of planar Dirac fermions by a superstrong Coulomb potential
Khalilov, V R
2016-01-01
We study the vacuum polarization of planar charged Dirac fermions by a strong Coulomb potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. For the massless case the induced vacuum charge density is localized at the origin when the Coulomb center charge is subcritical while it has a power-law tail when the Coulomb center charge is supercritical. The finite mass contribution into the induced charge due to the vacuum polarization is small and insignificantly distorts the Coulomb potential only at distances of order of the Compton length. The induced vacuum charge has a screening sign. As is known the quantum electrodynamics vacuum becomes unstable when the Coulomb center charge is increased from subcritical to supercritical values. In the supercritical Coulomb potential the quantum electrodynamics vacuum acquires the charge due to the so-called real vacuum polarization. We calculate the real vacuum polarizat...
Exponential representation in the Coulomb three-body problem
The exponential representation in the Coulomb three-body problem is considered. It is shown that the exponential variational expansion in relative coordinates r32, r31 and r21 has a number of advantages for the bound state calculations in Coulomb three-body systems. Moreover, it appears that the exponential (or Laplace-Fourier) representation of the Coulomb three-body problem is an optimal approach to analyse and solve various three-body problems. The optimization of nonlinear parameters in the trial wavefunctions is also considered. The developed methods are used to determine the highly accurate ground 11S(L = 0)-state energies and other bound state properties for a number of He-like two-electron ions (Li+, Be2+, B3+, C4+, N5+, O6+, F7+ and Ne8+). To represent the ground state energies of these He-like ions we apply the Z-1 expansion. The asymptotic form of the ground state wavefunctions at large electron-nuclear distances for the He-like ions is briefly discussed. Considered hypervirial theorems are of great interest for these ions, since they allow one to obtain some useful relations between different expectation values. The generalization of the exponential variational expansion in relative coordinates to the four-body non-relativistic systems is also considered
Strong Coulomb effects on pions produced in heavy ion collisons
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.
Photoelectron wave function in photoionization: plane wave or Coulomb wave?
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
Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.
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
Coulomb-dominated low-energy deuteron stripping
Analysis of a three-body model shows that Coulomb polarization of the deuteron has very little influence on the branching ratio A(d,p)/A(d,n) for transfer reactions on target nucleus A at very low deuteron energies (the Oppenheimer-Phillips effect). We see that polarization effects in transfer reactions are not related to the long range of the Coulomb field, but are caused by the more intense fields near the target nucleus. However, even in that region the induced dipole moment is limited by the deuteron binding, and it is small for low Z targets. We see in addition that the transfer amplitudes tend to be insensitive to any polarization admixtures in the entrance channel. On the other hand, the branching ratio can be affected by the Coulomb barrier for the bound final-state wave function of the proton, especially for very weakly bound final states. Brief remarks about the relation of stripping theory to special properties of the d+d system are included
Coherent superposition in the coulomb explosion spectra of H2+
Graphical abstract: Schematic diagram for charge-resonance enhanced ionization (CREI) and the calculated kinetic energy spectra of proton from the Coulomb explosion of H2+ with 100 fs, 791 nm laser pulses, the peak laser intensities are from 5.0 x 1013 to 8.8 x 1013 W/cm2. Display Omitted Highlights: → Our quantum dynamics calculations confirm the multi-peak structures in CE spectra. → The main sharp peaks are attributed to vibrationally coherent superposition. → The structures disappear at relative higher laser intensities. - Abstract: Quantum wave packet calculations have been carried out to interpret the multi-peak structures in the Coulomb explosion spectra at low laser intensities from 5.0 x 1013 to 8.8 x 1013 W/cm2. A clear mechanism in comparison with experiment is presented. The calculated results confirm the previous experimental observations. The main sharp peaks can be attributed to vibrationally coherent superposition. It is different from the proposed explanation of the recent experimental measurements, in which each main peak is attributed to Coulomb explosion occurring at the same critical internuclear distance for all definite vibrational levels after the dissociation of the molecular ion. Moreover, our calculations indicate that these structures disappear at relative higher laser intensities, which is also consistent with the experiment.
Salem-Vasconcelos, S.; Takagui, E.M.; Bechara, M.J.; Koide, K.; Dietzsch, O. (Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo (Brazil)); Jr, A.B.N. (Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil)); Takai, H. (Brookhaven National Laboratory, Upton, New York 11973 (United States))
1994-08-01
Coulomb-nuclear interference effects were investigated in the inelastic scattering of [sup 16]O and [sup 18]O by [sup 64]Zn. Measurements of elastic and inelastic angular distributions of [sup 18]O were performed at a laboratory energy of 49 MeV, over the angular range from [theta][sub lab][similar to]30[degree] to 85[degree]. The excitation functions of [sup 16]O and [sup 18]O ions were measured at incident energies between 29 and 46 MeV at [theta][sub lab]=174[degree]. 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 [sup 18]O first 2[sup +] state was found to be shifted towards forward angles by approximately 5[degree] (c.m.) with respect to the distorted-wave Born approximation calculations and by approximately 3.5[degree] (c.m.) with respect to the coupled-channels calculations. A pronounced Coulomb-nuclear interference minimum was seen in the excitation of [sup 64]Zn(2[sup +]) state by inelastic scattering of [sup 16]O projectiles, whereas no pronounced minimum was observed in target excitation by [sup 18]O projectiles. The elastic scattering data were analyzed with the optical model. The inelastic differential cross sections for the excitation of the first 2[sup +] states in the target and in the [sup 18]O projectile were analyzed using the distorted-wave Born approximation and also the coupled-channels approach with collective form factors.
Diffractive Excitation in DIS and pp Collisions
Avsar, Emil; Lönnblad, Leif
2007-01-01
We have in earlier papers presented an extension of Mueller's dipole cascade model, which includes subleading effects from energy conservation and running coupling as well as colour suppressed effects from pomeron loops via a ``dipole swing''. The model was applied to describe the total cross sections in pp and gamma*p collisions. In this paper we present a number of improvements of the model, in particular related to the confinement mechanism. A consistent treatment of dipole evolution and dipole--dipole interactions is achieved by replacing the infinite range Coulomb potential by a screened potential, which further improves the frame-independence of the model. We then apply the model to elastic scattering and diffractive excitation, where we specifically study the effects of different sources for fluctuations. In our formalism we can take into account contributions from all different sources, from the dipole cascade evolution, the dipole--dipole scattering, from the impact-parameter dependence, and from the...
Theoretical description of nuclear collective excitations
Repko, Anton
2016-01-01
Density functional theory is a preferred microscopic method for calculation of nuclear properties over the whole nuclear chart. Besides ground-state properties, which are calculated by Hartree-Fock theory, nuclear excitations can be described by means of Random Phase Approximation (RPA). The main objective of the present work is to give Skyrme RPA formalism for spherically symmetric nuclei, using the techniques of angular-momentum coupling. Various auxiliary topics, such as Hartree-Fock theory, Coulomb integral, center-of-mass corrections and pairing, are treated as well. RPA method is derived also for axially deformed nuclei. The derived formulae are then implemented in the computer code and utilized for calculation of some physical results. After thorough investigation of the precision aspects of the calculation, the following topics are treated as examples: toroidal nature of the low-energy (pygmy) part of the E1 resonance, giant resonances of various multipolarities in deformed nucleus Sm-154, and magneti...
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
Wave Function Frozen-Density Embedding: Coupled Excitations.
Höfener, Sebastian; Visscher, Lucas
2016-02-01
We report quasi-ab initio correlated ground-state and excitation-energy calculations for agglomerates consisting of several molecules with total system sizes of up to more than one hundred atoms using a combination of a density-fitted, approximate second-order coupled-cluster singles and doubles (RICC2) method and frozen-density embedding (FDE), denoted RICC2-in-RICC2. Working equations are presented for CC2 ground-state energies and approximate coupled excitation energies, which are a necessary prerequisite for investigations of potential energy surfaces (PESs) of both ground and excited states. The approach is applicable to all systems that can be decomposed into interacting individual molecules for which the RICC2 calculation itself is feasible. Because of the absence of exact exchange in the formalism and the possibility to efficiently evaluate Coulomb coupling integrals using density fitting or a dipole approximation, the coupling step is insignificant in terms of computation time. PMID:26653851
State-selective high-energy excitation of nuclei by resonant positron annihilation
Nikolay A. Belov
2015-02-01
Full Text Available In the annihilation of a positron with a bound atomic electron, the virtual γ photon created may excite the atomic nucleus. We put forward this effect as a spectroscopic tool for an energy-selective excitation of nuclear transitions. This scheme can efficiently populate nuclear levels of arbitrary multipolarities in the MeV regime, including giant resonances and monopole transitions. In certain cases, it may have higher cross sections than the conventionally used Coulomb excitation and it can even occur with high probability when the latter is energetically forbidden.
State-selective high-energy excitation of nuclei by resonant positron annihilation
Belov, Nikolay A., E-mail: belov@mpi-hd.mpg.de; Harman, Zoltán
2015-02-04
In the annihilation of a positron with a bound atomic electron, the virtual γ photon created may excite the atomic nucleus. We put forward this effect as a spectroscopic tool for an energy-selective excitation of nuclear transitions. This scheme can efficiently populate nuclear levels of arbitrary multipolarities in the MeV regime, including giant resonances and monopole transitions. In certain cases, it may have higher cross sections than the conventionally used Coulomb excitation and it can even occur with high probability when the latter is energetically forbidden.
The inelastic excitation probabilities of 40Ca, 90Zr and 208Pb impinged by 40Ca projectiles at bombarding energies between 10 and 100 MeV/nucleon are calculated in a model where the excitation amplitudes are evaluated along classical trajectories. The excited states are calculated in the random phase approximation and the nuclear and Coulomb excitations of both low lying states and giant resonances of the target and projectile are taken into account. A general feature of the calculated spectra for near grazing impact parameters and bombarding energies above 20 MeV/nucleon is the presence of broad regularly-spaced structures mainly due to the excitation of multiphonon states built with giant resonances. Cross section estimates for the inelastic excitations are given
X-Ray excited and photoluminescence of CdS1-xSex nanocrystals embedded in borosilicate glass matrix
Gomonnai A.V.
2001-03-01
Full Text Available The performed experimental studies of X-ray excited and photoluminescence, optical absorption and Raman scattering of CdS1-xSex nanocrystals, embedded in borosilicate glass matrix, have enabled the nanocrystal parameters (chemical composition, average radius, acceptor levels energy depth, electron-hole Coulomb interaction energy is to be determined.
Soulé, Paul; Jolicoeur, Thierry
2011-01-01
We study fractional quantum Hall states in the cylinder geometry with open boundaries. By truncating the Coulomb interactions between electrons we show that it is possible to construct infinitely many exact eigenstates including the ground state, quasiholes, quasielectrons and the magnetoroton branch of excited states.
Excited atoms. Vozbuzhdennye atomy
Smirnov, B.M.
1982-01-01
An examination is made of the properties of excited atoms and molecules, the processes of their formation in a gas and plasma, and the diffusion of excited atoms in a gas. A presentation is made of the processes in which excited and metastable atoms and molecules in a gas are destroyed upon collision with electrons, atoms, and molecules. A study is made of the relaxation of excited states during collisions - excitation transfer, depolarization, transitions between fine structure states, etc. Information is given on ionization that includes the participation of excited atoms - the Penning process, associative ionization. An examination is made of highly excited states of atoms and the processes that take place during their participation. The book is intended for personnel in the area of physics and chemistry of plasma, atomic and molecular physics, chemical physics as well as in allied areas of physics. 1280 references, 52 figures, 76 tables.
Quantum Coulomb Systems: Recombination, Screening, and van der Waals Forces
Under standard Earth conditions, and also in many astrophysical situations, the properties of matter result from the interplay between non-relativistic quantum mechanics and Coulomb interactions. In that context, the derivation of exact results for equilibrium properties of quantum Coulomb systems is of crucial importance. First, I briefly review rigorous proofs about either stability or limiting behaviours, as well as various asymptotic expansions specific to almost fully ionized situations. Then, I present the Feynman-Kac path integral representation which is the most efficient tool for dealing with both recombination and screening. Within that representation, the grand-canonical partition function for a system of quantum particles with two-body interactions is shown to be equal to its equivalent counterpart for a system of classical loops. Equilibrium quantities for the gas of loops are then represented by straightforward generalizations of standard Mayer diagrammatics. Because of the Coulomb-like long range of the two-body loop potential, every Mayer graph diverges. Such divergences are first removed via systematic chain resummations, which amount to introduce an effective potential φ, the quantum analogue of Debye potential. In a second step, the whole resumed diagrammatical series is exactly reorganized in terms of graphs where particle clusters are connected by bonds built with φ. The corresponding screened cluster representation is particularly useful for studying partially ionized gases, as illustrated by its application to hydrogen in the atomic regime. Exact asymptotic expansions for thermodynamics are derived beyond familiar Saha theory. Also, the screening of van der Waals forces between two hydrogen atoms by ionized protons and ionized electrons is shown to be only partial. (author)
A unitarized meson model including color Coulomb interaction
Ch. 1 gives a general introduction into the problem field of the thesis. It discusses in how far the internal structure of mesons is understood theoretically and which models exist. It discusses from a phenomenological point of view the problem of confinement indicates how quark models of mesons may provide insight in this phenomenon. In ch. 2 the formal theory of scattering in a system with confinement is given. It is shown how a coupled channel (CC) description and the work of other authors fit into this general framework. Explicit examples and arguments are given to support the CC treatment of such a system. In ch. 3 the full coupled-channel model as is employed in this thesis is presented. On the basis of arguments from the former chapters and the observed regularities in the experimental data, the choices underlying the model are supported. In this model confinement is described with a mass-dependent harmonic-oscillator potential and the presence of open (meson-meson) channels plays an essential role. In ch. 4 the unitarized model is applied to light scalar meson resonances. In this regime the contribution of the open channels is considerable. It is demonstrated that the model parameters as used for the description of the pseudo-scalar and vector mesons, unchanged can be used for the description of these mesons. Ch. 5 treats the color-Coulomb interaction. There the effect of the Coulomb interaction is studied in simple models without decay. The results of incorporating the color-Coulomb interaction into the full CC model are given in ch.6. Ch. 7 discusses the results of the previous chapters and the present status of the model. (author). 182 refs.; 16 figs.; 33 tabs