Heavy ion reactions around the Coulomb barrier
Institute of Scientific and Technical Information of China (English)
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.
Deep inelastic scattering near the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
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.
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.
Role of transfer reactions in heavy-ion collisions at the Coulomb barrier
Directory of Open Access Journals (Sweden)
Pollarolo Giovanni
2011-10-01
Full Text Available One and two neutron transfer reactions are discussed in the semiclassical formalism. The twoneutrons transfer cross sections are calculated in the successive approximation. Comparisons with new experimental data below the Coulomb barrier are discussed in term of transfer probabilities as a function of the distance of closest approach for Coulomb scattering.
Zhang, G. L.; Pan, M.
2016-10-01
The Coulomb barrier heights are calculated by using the proximity potential with a new universal function in comparison with the results of proximity potentials Prox77, AW95, Bass73, BW91, CW76, DP and Ng80. It is found that the new results of Coulomb barrier heights are better than those of most proximity potentials. Then this proximity potential with the new universal function was used to calculate the Coulomb barrier positions and heights from light fusion systems to heavy fusion systems. The parametrized formulas are obtained for Coulomb barrier height and position, and can reproduce most of calculated barrier heights and positions within the accuracy of ± 1%.
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.
Laser-driven recollisions under the Coulomb barrier
Keil, Th; Bauer, D
2016-01-01
Photoelectron spectra obtained from the ab initio solution of the time-dependent Schr\\"odinger equation can be in striking disagreement with predictions by the strong-field approximation (SFA) not only at low energy but also around twice the ponderomotive energy where the transition from the direct to the rescattered electrons is expected. In fact, the relative enhancement of the ionization probability compared to the SFA in this regime can be several orders of magnitude. We show for which laser and target parameters such an enhancement occurs and for which the SFA prediction is reasonably good. The enhancement is analyzed in terms of the Coulomb-corrected action along analytic quantum orbits in the complex-time plane, taking branch cuts due to soft-recollisions properly into account.
^{11}Li Breakup on ^{208}Pb at Energies Around the Coulomb Barrier
DEFF Research Database (Denmark)
Fernández-García, J.P.; Cubero, M.; Rodríguez-Gallardo, M.
2013-01-01
The inclusive breakup for the 11Li+208Pb reaction at energies around the Coulomb barrier has been measured for the first time. A sizable yield of 9Li following the 11Li dissociation has been observed, even at energies well below the Coulomb barrier. Using the first-order semiclassical perturbatio...
Multilayer ΔE-E Telescope for Breakup Reactions at Energies around Coulomb Barrier
Institute of Scientific and Technical Information of China (English)
MA; Nan-ru; LIN; Cheng-jian; YANG; Lei; WANG; Dong-xi; SUN; Li-jie; JIA; Hui-ming
2015-01-01
The reaction mechanisms of weakly-bound nuclear systems have attracted much attention lately.To study the Breakup reactions induced by loosely bound nuclei at energies around the Coulomb barrier,a new kind IC-based detector telescope was designed and manufactured,as shown in Fig.1.The combination of a PCB-made
Scattering of light halo nuclei on heavy target at energies around the Coulomb barrier
Directory of Open Access Journals (Sweden)
Tengblad O.
2014-03-01
Full Text Available We report here on experiments performed at TRIUMF to study the scattering of the light halo nuclei 11Li on lead at energies below and around the Coulomb barrier. The the elastic and break-up differential cross section are interpreted in the framework of Continuum-Discretized Coupled-Channel calculations. The departure from Rutherford scattering at energies below the barrier is well beyond the behavior of normal nuclei.
Scattering of light halo nuclei on heavy target at energies around the Coulomb barrier
Tengblad O.; Borge M.J.G.; Cubero M.; Nacher E.; Pesudo V.; Perea A.; Gomez-Camacho J.; Moro A. M.; Fernandez-Garcia J.P.; Alvarez M.A.G.; Rodriguez-Gallardo M.; Lay J. A.; Martel I.; Acosta L.; Sanchez-Benitez A.M.
2014-01-01
INPC 2013 – International Nuclear Physics Conference We report here on experiments performed at TRIUMF to study the scattering of the light halo nuclei 11Li on lead at energies below and around the Coulomb barrier. The the elastic and break-up differential cross section are interpreted in the framework of Continuum-Discretized Coupled-Channel calculations. The departure from Rutherford scattering at energies below the barrier is well beyond the behavior of normal nuclei Consejo Interins...
Matsumoto, T; Iseri, Y; Kamimura, M; Ogata, K; Yahiro, M
2006-01-01
We accurately analyze the $^6$He+$^{209}$Bi scattering at 19 and 22.5 MeV near the Coulomb barrier energy, using the continuum-discretized coupled-channels method (CDCC) based on the $n$+$n$+$^4$He+$^{209}$Bi four-body model. The three-body breakup continuum of $^6$He is discretized by diagonalizing the internal Hamiltonian of $^6$He in a space spanned by the Gaussian basis functions. The calculated elastic and total reaction cross sections are in good agreement with the experimental data, while the CDCC calculation based on the di-neutron model of $^6$He, i.e., the $^2n$+$^{4}$He+$^{209}$Bi three-body model, does not reproduce the data.
Analysis of uncertainties in alpha-particle optical-potential assessment below the Coulomb barrier
Avrigeanu, V
2016-01-01
Background: Recent high-precision measurements of alpha-induced reaction data below the Coulomb barrier have pointed out questions of the alpha-particle optical-model potential (OMP) which are yet open within various mass ranges. Purpose: The applicability of a previous optical potential and eventual uncertainties and/or systematic errors of the OMP assessment at low energies can be further considered on this basis. Method: Nuclear model parameters based on the analysis of recent independent data, particularly gamma-ray strength functions, have been involved within statistical model calculation of the (alpha,x) reaction cross sections. Results: The above-mentioned potential provides a consistent description of the recent alpha-induced reaction data with no empirical rescaling factors of the and/or nucleon widths. Conclusions: A suitable assessment of alpha-particle optical potential below the Coulomb barrier should involve the statistical-model parameters beyond this potential on the basis of a former analysi...
Elastic scattering and reaction mechanisms of the halo nucleus $^{11}$Be around the Coulomb barrier
Di Pietro, A; Fisichella, M; Borge, M J G; Randisi, G; Milin, M; Figuera, P; Gomez-Camacho, J; Raabe, R; Amorini, F; Fraile, L M; Rizzo, F; Zadro, M; Torresi, D; Wenander, F; Pellegriti, M G; Papa, M; Jeppesen, H; Santonocito, D; Scuderi, V; Acosta, L; Perez-Bernal, F; Tengblad, O; Lattuada, M; Musumarra, A; Scalia, G; Maira Vidal, A; Voulot, D
2010-01-01
Collisions induced by $^{9}$Be, $^{10}$Be, $^{11}$Be on a $^{64}$Zn target at the same c. m. energy were studied. For the first time, strong effects of the $^{11}$Be halo structure on elastic-scattering and reaction mechanisms at energies near the Coulomb barrier are evidenced experimentally. The elastic-scattering cross section of the $^{11}$Be halo nucleus shows unusual behavior in the Coulomb-nuclear interference peak angular region. The extracted total-reaction cross section for the $^{11}$Be collision is more than double the ones measured in the collisions induced by $^{9}$Be, $^{10}$Be. It is shown that such a strong enhancement of the total-reaction cross section with $^{11}$Be is due to transfer and breakup processes.
Fusion and Direct Reactions of Halo Nuclei at Energies around the Coulomb Barrier
Keeley, N; Raabe, R; Sida, J L
2007-01-01
The present understanding of reaction processes involving light unstable nuclei at energies around the Coulomb barrier is reviewed. The effect of coupling to direct reaction channels on elastic scattering and fusion is investigated, with the focus on halo nuclei. A list of definitions of processes is given, followed by a review of the experimental and theoretical tools and information presently available. The effect of couplings on elastic scattering and fusion is studied with a series of model calculations within the coupled-channels framework. The experimental data on fusion are compared to "bare" no-coupling one-dimensional barrier penetration model calculations. On the basis of these calculations and comparisons with experimental data, conclusions are drawn from the observation of recurring features. The total fusion cross sections for halo nuclei show a suppression with respect to the "bare" calculations at energies just above the barrier that is probably due to single neutron transfer reactions. The dat...
Scattering of {sup 6}He at energies around the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Sanchez-BenItez, A M [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Escrig, D [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Alvarez, M A G [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain)] [and others
2005-10-01
We have measured elastic cross sections of the scattering of {sup 6}He at E{sub Lab} = 14, 16, 17, 18 and 22 MeV on {sup 208}Pb in the angular ranges of 20 deg. - 64 deg. and 135 deg. - 170 deg. A significant amount of {sup 4}He events is found at energies well below the Coulomb barrier, that becomes dominant above it. Optical model calculations have been performed including a dynamic polarization potential. Very large imaginary diffuseness parameter is needed in order to describe the experimental distributions.
{sup 6}Li breakup and suppression of complete fusion above the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Elmahdy, N.A. [Modern Academy for Engineering and Technology, Cairo (Egypt); Denikin, A.S. [Dubna International University, Dubna (Russian Federation); JINR, Flerov Laboratory of Nuclear Reactions, Dubna (Russian Federation); Ismail, M.; Ellithi, A.Y. [Cairo University, Cairo (Egypt)
2015-05-15
We study the role of the projectile breakup in the fusion process by example of the {sup 6}Li reactions with the {sup 59}Co, {sup 144}Sm and {sup 209}Bi targets in vicinity of the Coulomb barrier. The coupled channel and distorted wave approaches are employed in order to calculate the complete fusion and the breakup cross sections, respectively. The partial cross sections in both the channels are compared in order to estimate the breakup fraction responsible for the suppression of complete fusion. The calculations are compared with available experimental data. The conclusions and recommendations are made. (orig.)
7Be- and 8B-reaction dynamics at Coulomb barrier energies
Directory of Open Access Journals (Sweden)
Mazzocco M.
2016-01-01
Full Text Available We investigated the reaction dynamics induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target at energies around the Coulomb barrier. The two measurements are strongly interconnected, being 7Be (Sα = 1.586 MeV the loosely bound core of the even more exotic 8B (Sp = 0.1375 MeV nucleus. Here we summarize the present status of the data analysis for the measurement of the elastic scattering process for both reactions and the preliminary results for the optical model analysis of the collected data.
7Be- and 8B-reaction dynamics at Coulomb barrier energies
Mazzocco, M.; Boiano, A.; Boiano, C.; La Commara, M.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Strano, E.; Torresi, D.; Yamaguchi, H.; Kahl, D.; Acosta, L.; Di Meo, P.; Fernandez-Garcia, J. P.; Glodariu, T.; Grebosz, J.; Guglielmetti, A.; Imai, N.; Hirayama, Y.; Ishiyama, H.; Iwasa, N.; Jeong, S. C.; Jia, H. M.; Keeley, N.; Kim, Y. H.; Kimura, S.; Kubono, S.; Lay, J. A.; Lin, C. J.; Marquinez-Duran, G.; Martel, I.; Miyatake, H.; Mukai, M.; Nakao, T.; Nicoletto, M.; Pakou, A.; Rusek, K.; Sakaguchi, Y.; Sánchez-Benítez, A. M.; Sava, T.; Sgouros, O.; Stefanini, C.; Soramel, F.; Soukeras, V.; Stiliaris, E.; Stroe, L.; Teranishi, T.; Toniolo, N.; Wakabayashi, Y.; Watanabe, Y. X.; Yang, L.; Yang, Y. Y.
2016-05-01
We investigated the reaction dynamics induced by the Radioactive Ion Beams 7Be and 8B on a 208Pb target at energies around the Coulomb barrier. The two measurements are strongly interconnected, being 7Be (Sα = 1.586 MeV) the loosely bound core of the even more exotic 8B (Sp = 0.1375 MeV) nucleus. Here we summarize the present status of the data analysis for the measurement of the elastic scattering process for both reactions and the preliminary results for the optical model analysis of the collected data.
Modified phase rule for inelastic scattering of heavy ions near the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Wohlfarth, D.; Hentschel, E.; Hersch, G.U.; Grambole, D.; Man' ko, V.I.; Sakuta, S.B.; Thomas, H.J.; Chuev, V.I.
1983-12-01
We propose a semiclassical model of heavy-ion inelastic scattering in which the difference in the entry and exit trajectories is taken into account. This model permits explanation of most of the experimentally observed deviations from the 180/sup 0/ phase rule formulated for elastic and inelastic scattering of heavy ions at energy near the Coulomb barrier. It is shown that in those cases when even the modified phase rule which follows from the semiclassical model does not agree with experiment, a two-stage mechanism gives a substantial contribution to inelastic scattering.
Fusion reaction around the Coulomb barrier with neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Yoshida, Atsushi [Institute of Physical and Chemical Research, Wako, Saitama (Japan)
1997-07-01
Two fusion reactions with neutron-rich nuclei are reported in this work. On the first reaction: {sup 9,10,11}Be+{sup 209}Bi, the fusion cross sections around the coulomb barrier were measured by determing {alpha} disintegration from compound nucleus Fr. In the field of 10-100 mb, the same total fusion cross sections were obtained. The phenomenon {sup 11}Be(neutron halo nucleus) alone increased and decreased was not observed. The fusion cross sections of {sup 27,29,31}Al+{sup 197}Au system were determined by using 130 kcps and 30 kcps of beam strength of {sup 29,31}Al, respectively. The value of {sup 27}Al was reproduced by calculation, but that of {sup 29}Al increased around barrier which could not be explained by CCDEF calculation. (S.Y.)
Breakup Effect of Weakly Bound Projectile on the Barrier Distribution Around Coulomb Barrier
Institute of Scientific and Technical Information of China (English)
贾会明; 林承键; 张焕乔; 刘祖华; 喻宁; 杨峰; 徐新星; 贾飞; 吴振东; 张世涛
2012-01-01
The excitation function of quasi-elastic （QEL） scattering at a backward angle has been measured for 9^Be＋208^Pb. The barrier distribution was extracted by means of the first derivative of the measured excitation function and calculated with the coupled-channel model. The present work shows that the experimental barrier distribution extracted from QEL scattering is shifted to the low energy side by 1.5 MeV as compared with the theoretical one. This energy discrepancy indicates that breakup is important in the colliding processes of the weakly bound nucleus system.
Scattering of 9Li on 208Pb at energies around the Coulomb barrier
Directory of Open Access Journals (Sweden)
Moro A.
2011-10-01
Full Text Available In order to study the dynamics of 11Li and 9Li beams in a strong electric ﬁeld at energies around the Coulomb barrier, we measured at the ISACII-TRIUMF Facility the angular distribution of elastic and inelastic scattering of 11Li+208Pb at 24.2 and 29.7 MeV and 9Li+208Pb at 24, 29.5 and 33 MeV laboratory energies. We present here the ﬁrst determination of the angular distribution of the cross section of 9Li+208Pb. The results are compared with theoretical calculations using the double-folding São Paulo Potential (SPP for the real part and a for the imaginary part a Woods-Saxon potential. A good overall agreement is obtained.
Structure Effects in Collisions Induced by Halo and Weakly Bound Nuclei Around the Coulomb Barrier
Scuderi, V; Torresi, D; Fisichella, M; Borge, M J G; Randisi, G; Milin, M; Figuera, P; Raabe, R; Di Pietro, A; Amorini, F; Fraile, L M; Vidal, A M; Rizzo, F; Zadro, M; Gomez-Camacho, J; Pellegriti, M G; Papa, M; Jeppesen, H; Santonocito, D; Sanchez, E M R; Acosta, L; Tengblad, O; Lattuada, M; Musumarra, A; Scalia, G
2010-01-01
In this contribution, results concerning different reaction channels for the collisions induced by the three Be isotopes, Be-9,Be-10,Be-11, on a Zn-64 target at energies around the Coulomb barrier will be presented. The experiments with the radioactive Be-10,Be-11 beams were performed at REX-ISOLDE (CERN) whereas the experiment with the stable weakly bound Be-9 beam was performed at LNS Catania. Elastic scattering angular distributions have been measured for the three systems Be-9,Be-10,Be-11 + Zn-64 at the same center of mass energy. The angular distributions were analyzed with optical potentials and reaction cross sections were obtained from optical model calculations, performed with the code PTOLEMY. For the Be-11 + Zn-64 reaction, the break-up angular distribution was also measured.
Universal trend for heavy-ion total reaction cross sections at energies above the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Tavares, O.A.P.; Medeiros, E.L., E-mail: emil@cbpf.b [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Morcelle, V. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica
2010-06-15
Heavy-ion total reaction cross section measurements for more than one thousand one hundred reaction cases covering 61 target nuclei in the range {sup 6}Li-{sup 238}U, and 158 projectile nuclei from {sup 2}H up to {sup 84}Kr (mostly exotic ones) have been analysed in a systematic way by using an empirical, three-parameter formula which is applicable to cases for projectile kinetic energies above the Coulomb barrier. The analysis has shown that the average total nuclear binding energy per nucleon of the interacting nuclei and their radii are the chief quantities which describe the cross section patterns. A great number of cross section data (87%) has been quite satisfactorily reproduced by the proposed formula, therefore total reaction cross section predictions for new, not yet experimentally investigated reaction cases can be obtained within 25 percent (or much less) of uncertainty (author)
Absolute Cross Sections for Proton Induced Reactions on 147,149Sm Below the Coulomb Barrier
Gheorghe, I.; Filipescu, D.; Glodariu, T.; Bucurescu, D.; Cata-Danil, I.; Cata-Danil, G.; Deleanu, D.; Ghita, D.; Ivascu, M.; Lica, R.; Marginean, N.; Marginean, R.; Mihai, C.; Negret, A.; Sava, T.; Stroe, L.; Toma, S.; Sima, O.; Sin, M.
2014-05-01
Cross sections for 147,149Sm(p,n)147,149Eu and 147,149Sm(p, γ)148,150Eu were measured using the activation method. The results are compared to the predictions of the Hauser-Feshbach statistical model. Different γ-ray strength functions have been tested against the experimental values. In the case of 150Eu, in order to reproduce the experimental isomeric population cross sections, various scenarios for unknown branching ratios of certain discrete states have been discussed. The results provide constraints for the optical model parameters dedicated to this insufficiently known area of isotopes. Such cross sections for (p, γ) reactions at energies below the Coulomb barrier are valuable for p-process nucleosynthesis calculations.
Microscopic study of {sup 6}He elastic scattering around the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Descouvemont, P. [Physique Nucléaire Théorique et Physique Mathématique, C.P. 229, Université Libre de Bruxelles (ULB), B 1050 Brussels (Belgium)
2016-07-07
We investigate {sup 6}He scattering on {sup 27}Al, {sup 58}Ni, {sup 120}Sn, and {sup 208}Pb in a microscopic version of the Continuum Discretized Coupled Channel (CDCC) method. We essentially focus on energies around the Coulomb barrier. The {sup 6}He nucleus is described by an antisymmetric 6-nucleon wave function, defined in the Resonating Group Method. The {sup 6}He continuum is simulated by square-integrable positive-energy states. The model does not depend on any adjustable parameter as it is based only on well known nucleon-target potentials. We show that experimental elastic cross sections are fairly well reproduced. The calculation suggests that breakup effects increase for high target masses. For a light system such as {sup 6}He+{sup 27}Al, breakup effects are small, and a single-channel approximation provides fair results.
N-Protonated Isomers and Coulombic Barriers to Dissociation of Doubly Protonated Ala8Arg
Haeffner, Fredrik; Irikura, Karl K.
2017-10-01
Collision-induced dissociation (or tandem mass spectrometry, MS/MS) of a protonated peptide results in a spectrum of fragment ions that is useful for inferring amino acid sequence. This is now commonplace and a foundation of proteomics. The underlying chemical and physical processes are believed to be those familiar from physical organic chemistry and chemical kinetics. However, first-principles predictions remain intractable because of the conflicting necessities for high accuracy (to achieve qualitatively correct kinetics) and computational speed (to compensate for the high cost of reliable calculations on such large molecules). To make progress, shortcuts are needed. Inspired by the popular mobile proton model, we have previously proposed a simplified theoretical model in which the gas-phase fragmentation pattern of protonated peptides reflects the relative stabilities of N-protonated isomers, thus avoiding the need for transition-state information. For singly protonated Ala n ( n = 3-11), the resulting predictions were in qualitative agreement with the results from low-energy MS/MS experiments. Here, the comparison is extended to a model tryptic peptide, doubly protonated Ala8Arg. This is of interest because doubly protonated tryptic peptides are the most important in proteomics. In comparison with experimental results, our model seriously overpredicts the degree of backbone fragmentation at N9. We offer an improved model that corrects this deficiency. The principal change is to include Coulombic barriers, which hinder the separation of the product cations from each other. Coulombic barriers may be equally important in MS/MS of all multiply charged peptide ions. [Figure not available: see fulltext.
17O+58Ni scattering and reaction dynamics around the Coulomb barrier
Strano, E.; Torresi, D.; Mazzocco, M.; Keeley, N.; Boiano, A.; Boiano, C.; Di Meo, P.; Guglielmetti, A.; La Commara, M.; Molini, P.; Manea, C.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Grebosz, J.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Nicoletto, M.; Pakou, A.; Rusek, K.; Sgouros, O.; Soukeras, V.; Stroe, L.; Toniolo, N.; Vitturi, A.; Watanabe, Y.; Zerva, K.
2016-08-01
This work aims at investigating the projectile binding energy influence on the reaction dynamics, introducing new results and new data analysis methods in order to overcome some typically encountered problems, such as the identification of reaction products differing by few mass units and the discrimination of direct reaction processes. The 17O+58Ni collision was studied at five near-barrier energies employing a compact experimental setup consisting of four double-sided silicon strip detectors (DSSSDs). Different reaction processes, namely the elastic and inelastic scattering and the 1 n stripping, were discriminated by means of a detailed analysis of the experimental energy spectra based on Monte Carlo simulations. The elastic scattering angular distributions were investigated within the framework of the optical model using Woods-Saxon and double-folding potentials. The total reaction cross sections were extracted and the reduced cross sections compared with those obtained for 17F (Sp=0.600 MeV), the mirror nucleus of 17O (Sn=4.143 MeV), and for the tightly bound 16O projectile. The 17O+58Ni total reaction cross sections were larger than those for 16O on the same target at the lowest energies studied, becoming identical, within errors, as the incident energy increased above the Coulomb barrier. This behavior was related to a strong contribution from the 1 n -stripping channel at the lowest energies.
Elastic scattering of 17O+208Pb at energies near the Coulomb barrier
Directory of Open Access Journals (Sweden)
Torresi D.
2016-01-01
Full Text Available Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.
Elastic scattering of 17O+208Pb at energies near the Coulomb barrier
Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.
2016-05-01
Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.
Escrig, Diego; Sánchez Benítez, Ángel Miguel; Moro, A. M.; González Álvarez, Marcos A.; Andrés, M. V.; Angulo, C.; García Borge, María José; Cabrera Caño, Jesús; Cherubini, S.; Damaret, P.; Espino, José Manuel; Figuera, P.; Freer, M.; García Ramos, José Enrique; Gómez Camacho, Joaquín
2007-01-01
New experimental data from the scattering of 6He + 208Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of α particles. The energy and angular distribution of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the α particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakly bound state...
alpha-particle production in the scattering of 6He by 208Pb at energies around the Coulomb barrier
Escrig, D.; Sanchez-Benitez, A M; Moro, A. M.; Alvarez, M. A. G.; Andres, M. V.; Angulo, C.; Borge, M. J. G.; J. Cabrera; Cherubini, S.; Demaret, P; Espino, J. M.; Figuera, P.; Freer, M.; Garcia-Ramos, J. E.; Gomez-Camacho, J.
2007-01-01
New experimental data from the scattering of 6He+208Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of $\\alpha$ particles. The energy and angular distributions of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the $\\alpha$ particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakl...
Structure effects in the reactions {sup 9,10,11}Be+{sup 64}Zn at the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Scuderi, V; Amorini, F; Fisichella, M; Lattuada, M; Pellegriti, M G; Randisi, G; Rizzo, F [Dipartimento di Fisica ed Astronomia Universita di Catania, Catania (Italy); Pietro, A Di; Figuera, P; Musumarra, A; Papa, M [INFN-Laboratori Nazionali del Sud and Sezione di Catania (Italy); Acosta, L; Martel, I; Perez-Bernal, F [Departamento de Fisica Aplicada Universidad de Huelva, Huelva (Spain); Borge, M J G [Instituto de Estructura de la Materia CSIC, Madrid (Spain); Fraile, L M; Jeppesen, H [CERN, Geneva (Switzerland); Gomez-Camacho, J [Departamento de Fisica Atomica Molecular Nuclear Universidad de Sevilla, Sevilla (Spain); Milin, M [Department of Physics Faculty of Science University of Zagreb, Zagreb (Croatia); Raabe, R, E-mail: scuderiv@lns.infn.it [Instituut voor Kern-en Stralingsfysica University of Leuven, Leuven (Belgium)
2011-01-01
Elastic scattering and direct reactions have been studied for the collisions induced by the three Beryllium isotopes {sup 9,10,11}Be, on a medium mass {sup 64}Zn target at energies around the Coulomb barrier. The elastic scattering angular distributions, measured for the three systems at the same center of mass energy, were analyzed within the Optical Model and reaction cross-sections were deduced from optical model calculations. For the {sup 11}Be induced reaction the transfer/break-up angular distribution was also extracted.
Wang, Bing; Diaz-Torres, Alexis; Zhao, En-Guang; Zhou, Shan-Gui
2016-01-01
Complete fusion excitation functions of reactions involving breakup are studied by using the empirical coupled-channel (ECC) model with breakup effects considered. An exponential function with two parameters is adopted to describe the prompt-breakup probability in the ECC model. These two parameters are fixed by fitting the measured prompt-breakup probability or the complete fusion cross sections. The suppression of complete fusion at energies above the Coulomb barrier is studied by comparing the data with the predictions from the ECC model without the breakup channel considered. The results show that the suppression of complete fusion are roughly independent of the target for the reactions involving the same projectile.
Escrig, D; Moro, A M; Alvarez, M A G; Andrés, M V; Angulo, C; García-Borge, M J; Cabrera, J; Cherubini, S; Demaret, P; Espino, J M; Figuera, P; Freer, M; García-Ramos, J E; Gómez-Camacho, J; Gulino, M; Kakuee, O R; Martel, I; Metelko, C; Pérez-Bernal, F; Rahighi, J; Rusek, K; Smirnov, D; Tengblad, O; Ziman, V
2007-01-01
New experimental data from the scattering of 6He+208Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of $\\alpha$ particles. The energy and angular distributions of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the $\\alpha$ particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakly bound states of the final nucleus.
Energy Technology Data Exchange (ETDEWEB)
Lizcano, D.; Aguilera, E.F.; Garcia M, H.; Martinez Q, E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)
2004-07-01
Protons, alpha particles and deuterons coming from the reactions {sup 6} Li + {sup 58} Ni are detected to three different energy around the Coulomb barrier. The possible effects of the weakly bound character of the projectile are studied and the results are compared with previous data for the system {sup 6} Li + {sup 59} Co. (Author)
Bourgin, D.; Courtin, S.; Haas, F.; Stefanini, A. M.; Montagnoli, G.; Goasduff, A.; Montanari, D.; Corradi, L.; Fioretto, E.; Huiming, J.; Scarlassara, F.; Rowley, N.; Szilner, S.; Mijatović, T.
2014-10-01
Background: The nuclear structure of colliding nuclei is known to influence the fusion process. Couplings of the relative motion to nuclear shape deformations and vibrations lead to an enhancement of the sub-barrier fusion cross section in comparison with the predictions of one-dimensional barrier penetration models. This enhancement is explained by coupled-channels calculations including these couplings. The sub-barrier fusion cross section is also affected by nucleon transfer channels between the colliding nuclei. Purpose: The aim of the present experiment is to investigate the influence of the projectile and target nuclear structures on the fusion cross sections in the Ca40+Ni58 and Ca40+Ni64 systems. Methods: The experimental and theoretical fusion excitation functions as well as the barrier distributions were compared for these two systems. Coupled-channels calculations were performed using the ccfull code. Results: Good agreement was found between the measured and calculated fusion cross sections for the Ca40+Ni58 system. The situation is different for the Ca40+Ni64 system where the coupled-channels calculations with no nucleon transfer clearly underestimate the fusion cross sections below the Coulomb barrier. The fusion excitation function was, however, well reproduced at low and high energies by including the coupling to the neutron pair-transfer channel in the calculations. Conclusions: The nuclear structure of the colliding nuclei influences the fusion cross sections below the Coulomb barrier for both Ca40+Ni58,64 systems. Moreover, we highlighted the effect of the neutron pair-transfer channel on the fusion cross sections in Ca40+Ni64.
First time evidence of pronounced plateaus right above the Coulomb barrier in 8Li + 4He fusion
Directory of Open Access Journals (Sweden)
A. Del Zoppo
2016-02-01
Full Text Available We investigate unprecedented experimental information on the fusion reaction induced by the radioactive projectile 8Li on a 4He gas target, at center-of-mass energies between 0.6 and 5 MeV. The main issue is the tendency of the dimensionless fusion cross section σfπƛ2 to form well visible plateaus alternated to steep rises. This finding is likely to be the most genuine consequence of the discrete nature of the intervening angular momenta observed so far in fusion reactions right above the Coulomb barrier. A partial-wave analysis, exclusively based on a pure quantal penetration fusion model and sensitive to the interaction potential, identifies a remarkably low-height barrier.
Effect of neutron transfer in the fusion process near and below the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Rachkov, V. A.; Adel, A.; Karpov, A. V.; Denikin, A. S.; Zagrebaev, V. I. [Flerov Laboratory of Nuclear Reactions, JINR, Dubna, 141980, Moscow region (Russian Federation); Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Flerov Laboratory of Nuclear Reactions, JINR, Dubna, 141980, Moscow region (Russian Federation); Flerov Laboratory of Nuclear Reactions, JINR, Dubna, 141980, Moscow region (Russian Federation) and International University ' Dubna' , Dubna, 141980, Moscow region (Russian Federation); Flerov Laboratory of Nuclear Reactions, JINR, Dubna, 141980, Moscow region (Russian Federation)
2012-10-20
Near-barrier and sub-barrier fusion of weakly bound neutron-rich isotopes of lithium is explored within the empirical channel coupling model. Several combinations of colliding nuclei are proposed, for which strong enhancement of the sub-barrier fusion is predicted owing to coupling with neutron transfer channels.
Energy Technology Data Exchange (ETDEWEB)
Gautam, Manjeet Singh [Thapar University, School of Physics and Materials Science, Patiala (India); Indus Degree College, Department of Physics, Kinana, Jind, Haryana (India); Grover, Neha; Sharma, Manoj K. [Thapar University, School of Physics and Materials Science, Patiala (India)
2017-01-15
The complete fusion (CF) and incomplete fusion (ICF) cross-sections are estimated for {sup 6,} {sup 7}Li + {sup 159}Tb reactions using the energy-dependent Woods-Saxon potential model (EDWSP model) and dynamical cluster-decay model (DCM). The CF data of the {sup 6}Li + {sup 159}Tb({sup 7}Li + {sup 159}Tb) reaction at above barrier energies is suppressed with reference to expectations of the EDWSP model by 25% (20%) which is smaller than the reported data by ∝ 9% (6%). This suppression is correlated with the projectile breakup effect. The projectiles {sup 6,7}Li are loosely bound systems, which may break up into charged fragments prior to reaching the fusion barrier and subsequently one of the fragment is captured by the target leading to the suppression of fusion data at above barrier energies. The sum of CF and ICF, which is termed as total fusion cross-section (TF), removes the discrepancies between theoretical predictions and the above barrier complete fusion data and hence is adequately explained via the EDWSP model over a wide range of energy spread across the Coulomb barrier. In addition to fusion, the decay mechanism of {sup 6}Li + {sup 159}Tb reaction is studied within the framework of the dynamical cluster-decay model (DCM). The breakup of the projectile ({sup 6}Li) in the entrance channel indicates the presence of ICF, which is investigated further using the collective clusterization approach of DCM. The present theoretical analysis suggests that a larger barrier modification is needed to address the fusion data of chosen reactions in the below barrier energy region. (orig.)
Reaction study of {sup 11}Li on {sup 208}Pb target at energies close the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Cubero, Mario; Jose Borge, Maria; Tengblad, Olof; Alcorta, Martin; Madurga, Miguel [Instituto de Estructura de la Materia, Madrid (Spain); Camacho, Joaquin [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Sevilla (Spain); Martel, Ismael [Departamento de Fisica Aplicada, Universidad de Huelva, Huelva (Spain); Walden, Pat [TRI-University Meson Facilities, University of British Columbia, Vancouver (Canada)
2009-07-01
In the past 20 years there has been interest among the nuclear physics community to study the exotic properties observed in halo nuclei such as {sup 11}Li. Recent theoretical calculations predicted a deviation of the elastic cross section from the standard Rutherford formula, expected due to the dipole structure formed by the {sup 9}Li core and the halo neutrons when passing near the strong Coulomb produced by the Pb target. To explore this effect, the scattering and breakup reactions of the two-neutron halo nucleus {sup 11}Li were measured at ISACII-TRIUMF. Data was obtained at energies around, below and above the Coulomb barrier, 2.7 MeV/u. We used a set of four telescopes with PAD silicon detectors behind in order to clearly identified all fragments in the full detection angles covering 10-140 degree.In this contribution we present the analysis of the {sup 9}Li scattering data that it is needed to understand the effect on the {sup 11}Li cross sections. We also present preliminary results of the {sup 11}Li scattering.
Amador-Valenzuela, P.; Aguilera, E. F.; Martinez-Quiroz, E.; Lizcano, D.; Morales-Rivera, J. C.
2017-07-01
Recently, experimental measurements of elastic scattering angular distributions for the system7Li+58Ni at ten different energies around the Coulomb barrier were made by the Heavy-Ion Group. The measurements were made at the Tandem Van de Graaff Particle Accelerator Laboratory in the National Institute for Nuclear Research (ININ) in Mexico. In this work, preliminary elastic scattering angular distributions for five energies (E lab , = 12.0, 12.5, 13.0, 13.5 and 14.22 MeV) are presented. The preliminary experimental data were analyzed using the São Paulo Optical Model Potential (SPP) which is based on a double-folding potential, reproducing very well these data. A comparison is made with old data reported back in 1973 and in 2012. Further analysis is in progress in order to fully understand this particular system, specially because7Li is known to be a weakly bound nucleus.
Universal trend for heavy-ion total reaction cross-sections at energies above the Coulomb barrier
Tavares, O. A. P.; Medeiros, E. L.; Morcelle, V.
2010-08-01
Heavy-ion total reaction cross-section measurements for more than 1100 reaction cases covering 61 target nuclei in the range 6Li-238U and 158 projectile nuclei from 2H to 84Kr (mostly exotic ones) have been analyzed in a systematic way by using an empirical, three-parameter formula that is applicable to the cases of projectile kinetic energies above the Coulomb barrier. The analysis has shown that the average total nuclear binding energy per nucleon of the interacting nuclei and their radii are the chief quantities that describe the cross-section patterns. A great amount of cross-section data (87%) has been quite satisfactorily reproduced by the proposed formula; therefore, the total reaction cross-section predictions for new, not yet experimentally investigated reaction cases can be obtained within 25% (or much less) uncertainty. Dedicated to CBPF—Centro Brasileiro de Pesquisas Físicas in its celebration of the 60th anniversary of its foundation.
A multilayer ΔE-E R telescope for breakup reactions at energies around the Coulomb barrier
Ma, Nan-Ru; Lin, Cheng-Jian; Wang, Jian-Song; Yang, Lei; Wang, Dong-Xi; Zheng, Lei; Xu, Shi-Wei; Sun, Li-Jie; Jia, Hui-Ming; Ma, Jun-Bing; Ma, Peng; Jin, Shi-Lun; Bai, Zhen; Yang, Yan-Yun; Xu, Xin-Xing; Zhang, Gao-Long; Yang, Feng; He, Jian-Jun; Zhang, Huan-Qiao; Liu, Zu-Hua
2016-11-01
The breakup reactions of weakly-bound nuclei at energies around the Coulomb barrier and the corresponding coupling effect on the other reaction channels are hot topics nowadays. To overcome the difficulty in identifying both heavier and lighter fragments simultaneously, a new kind of ionization-chamber based detector telescope has been designed and manufactured. It consists of a PCB ionization chamber and three different thickness silicon detectors installed inside the chamber, which form a multilayer ΔE-E R telescope. The working conditions were surveyed by using an α source. An in-beam test experiment shows that the detector has good particle identification for heavy particles like 17F and 16O as well as light particles like protons and alpha particles. The measured quasi-elastic scattering angular distribution and the related discussions for 17F+208Pb are presented. Supported by National Key Basic Research Development Program of China (2013CB834404) and National Natural Science Foundation of China (11375268, 11475263, U1432127, U1432246).
Extending the class of solvable potentials: II. Screened Coulomb potential with a barrier
Alhaidari, A D
2010-01-01
This is the second article in a series where we succeed in enlarging the class of solvable problems in one and three dimensions. We do that by working in a complete square integrable basis that carries a tridiagonal matrix representation of the wave operator. Consequently, the wave equation becomes equivalent to a three-term recursion relation for the expansion coefficients of the wavefunction in the basis. Finding solutions of the recursion relation is equivalent to solving the original problem. This method gives a larger class of solvable potentials. The usual diagonal representation constraint results in a reduction to the conventional class of solvable potentials. However, the tridiagonal requirement allows only very few and special potentials to be added to the solvability class. In the present work, we obtain S-wave solutions for a three-parameter 1/r singular but short-range potential with a non-orbital barrier and study its energy spectrum. We argue that it could be used as a more appropriate model fo...
Study of the elastic scattering of 6He on 208Pb at energies around the Coulomb barrier
Sanchez-Benitez, A M; Escrig, D.; Alvarez, M. A.; Andres, M. V.; Angulo, Carmen; Borge, M. J. G.; J. Cabrera; Cherubini, F.; Demaret, P; Espino, J. M.; Figuera, P.; Freer, Martin; Garcia-Ramos, J. E.; Gomez-Camacho, J.; Gulino, M.
2008-01-01
The elastic scattering of 6He on 208Pb has been measured at laboratory energies of 14, 16, 18 and 22 MeV. These data were analyzed using phenomenological Woods- Saxon form factors and optical model calculations. A semiclassical polarization po- tential was used to study the e ect of the Coulomb dipole polarizability. Evidence for long range absorption, partially arising from Coulomb dipole polarizability, is reported. The energy variation of the optical potential was found to b...
Study of the elastic scattering of {sup 6}He on {sup 208}Pb at energies around the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Sanchez-Benitez, A.M. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Escrig, D. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Alvarez, M.A.G.; Andres, M.V. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain); Angulo, C. [Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Borge, M.J.G. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Cabrera, J. [Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Cherubini, S. [INFN Laboratori Nazionali del Sud, I-95123 Catania (Italy); Demaret, P. [Centre de Recherches du Cyclotron, Universite Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Espino, J.M. [Dept. de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain); Figuera, P. [INFN Laboratori Nazionali del Sud, I-95123 Catania (Italy); Freer, M. [School of Physics and Astronomy, University of Birmingham, B15 2TT Birmingham (United Kingdom); Garcia-Ramos, J.E. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Gomez-Camacho, J. [Dept. de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain); Gulino, M. [INFN Laboratori Nazionali del Sud, I-95123 Catania (Italy); Kakuee, O.R. [Van der Graaff Laboratory, Nuclear Research Centre, AEOI, PO Box 14155-1339, Tehran (Iran, Islamic Republic of); Martel, I. [Dept. de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain)], E-mail: imartel@uhu.es; Metelko, C. [School of Physics and Astronomy, University of Birmingham, B15 2TT Birmingham (United Kingdom); Moro, A.M. [Dept. de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, E-41080 Sevilla (Spain)] (and others)
2008-04-15
The elastic scattering of {sup 6}He on {sup 208}Pb has been measured at laboratory energies of 14, 16, 18 and 22 MeV. These data were analyzed using phenomenological Woods-Saxon form factors and optical model calculations. A semiclassical polarization potential was used to study the effect of the Coulomb dipole polarizability. Evidence for long range absorption, partially arising from Coulomb dipole polarizability, is reported. The energy variation of the optical potential was found to be consistent with the dispersion relations which connect the real and imaginary parts of the potential.
Energy Technology Data Exchange (ETDEWEB)
Escrig, D. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Sanchez-Benitez, A.M. [Departamento de Fisica Aplicada, Universidad de Huelva, E-21071 Huelva (Spain); Institut de Physique Nucleaire and Centre de Recherches du Cyclotron, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Moro, A.M. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain)]. E-mail: moro@us.es (and others)
2007-08-01
New experimental data from the scattering of {sup 6}He + {sup 208}Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of {alpha} particles. The energy and angular distribution of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the {alpha} particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakly bound states of the final nucleus.
Directory of Open Access Journals (Sweden)
Parascandolo C.
2011-10-01
Full Text Available The scattering processes of two mirror projectiles, the well bound 17O (Sn = 4.143 MeV and the loosely bound radioactive 17F (Sp = 0.600 MeV, on the proton closed shell target 58Ni were measured at several energies around the Coulomb barrier. The experimental data were analyzed within the framework of the optical model to extract the reaction cross section and to investigate the role played by direct reaction channels at near-barrier energies. The comparison shows a similar behaviour for the two A = 17 projectiles despite their very different binding energies and suggests a rather small effect of the 17F breakup channel on the reaction dynamics.
Elastic scattering of the halo nucleus {sup 6}He from {sup 208}Pb above the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Kakuee, O.R.; Rahighi, J.; Sanchez-Benitez, A.M.; Andres, M.V.; Cherubini, S.; Davinson, T.; Galster, W.; Gomez-Camacho, J. E-mail: gomez@nucle.us.es; Laird, A.M.; Lamehi-Rachti, M.; Martel, I.; Shotter, A.C.; Smith, W.B.; Vervier, J.; Woods, P.J
2003-12-15
Elastic scattering of {sup 6}He at E{sub lab}=27 MeV with {sup 208}Pb has been measured in the angular range of 6 deg.-72 deg.in the laboratory system employing LEDA and LAMP detection systems. Optical Model calculations have been performed using dynamic polarisation potential. The role of Coulomb dipole polarizability has been investigated. Large values of the imaginary diffuseness parameter are required in order to fit the data.
Fusion of sup 4 sup 0 Ca+ sup 1 sup 2 sup 4 Sn around the Coulomb barrier
Scarlassara, F; Montagnoli, G; Segato, G F; Ackermann, D; Corradi, L; Lin, C J; Stefanini, A M; Zheng, L F
2000-01-01
Fusion-evaporation cross sections of sup 4 sup 0 Ca+ sup 1 sup 2 sup 4 Sn have been measured with good precision and the barrier distribution extracted, following a complementary experiment on multinucleon transfer on the same system. The completeness of the data allows to constrain the fusion calculations concerning the effect of transfer coupling. The measured cross sections are strongly enhanced below the barrier compared to the one-dimensional barrier penetration estimate and the 'barrier distribution' is broad with no clear peak structure. Those features, together with transfer Q-values and cross sections make this system very similar to sup 4 sup 0 Ca+ sup 9 sup 6 Zr where there were also hints of significant transfer effects. Simplified coupled-channel calculations fail to reproduce the low energy tail of the data, although the barrier distribution is qualitatively reproduced. At a few energies, also the fusion of sup 4 sup 0 Ca+ sup 1 sup 1 sup 6 Sn has been measured and found to be very similar to th...
Excitation Functions of Fusion and Fission for 32S+170Er at Energies Near and Below Coulomb Barrier
Institute of Scientific and Technical Information of China (English)
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
Energy Technology Data Exchange (ETDEWEB)
Morcelle, Viviane; Gomes, P.R.S.; Lubian, J.; Mendes Junior, D.R. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Camargo, O.; Faria, P.N. de; Gasquez, L.; Morais, M.C.; Condori, R.P.; Pires, K.C.C.; Scarduelli, V. [Universidade de Sao Paulo (USP), SP (Brazil); Barioni, A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Zamora, J.C. [Technische Universitaet Darmstadt (Germany); Aguilera, E.; Martinez-Quiroz, E. [Instituto Nacional de Investigaciones Nucleares (Mexico); Kolata, J.; Jiang, H. [University of Notre Dame, IN (United States); Bechetti, F.D.; Lamm, L.O. [Michigan University, MI (United States); Lizcano, D. [Universidad Autonoma del Estado de Mexico (Mexico)
2012-07-01
Full text: Elastic scattering measurements were performed at energies around the Coulomb barrier at the Tandem Accelerators of the Sao Paulo (USP - Brazil ) and Notre Dame (UND - USA) Universities. The {sup 7}Be is a radioactive nucleus and has been produced by the reaction {sup 6}He({sup 6}Li,{sup 9}Be) and impinged on {sup 27}Al and {sup 197}Au secondary targets using a double superconducting systems RIBRAS ( USP ) and Twinsol (UND). The elastic scattering angular distributions were analyzed through the optical model calculations, using the Woods- Saxon form factors [1] and the Sao Paulo potential [2] to fit the experimental data. The total reaction cross sections were also derived and compared with others presented at the literature for other systems. In addition, a study of the nuclear potential energy dependence has been carried out in this work in the dispersion relation context. Due to the fact that {sup 7}Be has a small breakup threshold energy, the results can provide significant information of the influence of the breakup channel on the reactions involving this projectile. For this purpose, {chi}{sup 2}- data analysis with different kind of potentials were performed to identify the energy dependence of the real (V) and imaginary (W) parts of the potential. [1] L.C. Chamon et al., Phys. Rev. C 66, (2002) 014610. [2] R.D. Wood e D.S. Saxon, Phys. Rev. 95 ( 1954) 577. (author)
On the role of deformed Coulomb potential in fusion using energy density formalism
Indian Academy of Sciences (India)
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.
Energy Technology Data Exchange (ETDEWEB)
Lizcano C, D
2003-07-01
In recent experiments, the fusion of the exotic radioactive nucleus {sup 6} He with {sup 209} Bi has been studied for the first time at energies above and below the Coulomb barrier. A considerable enhancement in the fusion was observed, which implies a reduction of about 25% in the nominal fusion barrier. Some previous theoretical works suggest that this striking effect may be caused by the coupling to neutron transfer channels with a positive Q-value which would lead to a neutron flow and the consequent formation of a neck between the projectile and the target. Later, in the current work, we ran two new experiments on the same reaction using the FN Tandem Van de Graaff (10 MV) accelerator and the dual superconducting TwinSol system, both of them belonging to the University of Notre Dame, USA. This time, the purpose was to study one- and two-neutron transfer and the {sup 6} He projectile breakup at laboratory energies of 14.7, 16.2, 17.9, 19.0 and 22.5 MeV. A strong group of {sup 4} He was observed (with an effective Q-value about .5 MeV) whose integrated cross section results exceptionally high, exceeding the fusion cross section both above and below the barrier. The simultaneously measured elastic scattering angular distribution required high total cross sections so that this yield is confirmed. Preliminary coupled channels calculations sing the computer program called Fresco developed at the University of Surrey (England) suggested that the reaction mechanisms may be better described as a direct nuclear breakup and two-neutron transfer to unbound states in {sup 211} Bi. These calculations predicted also an enhancement in the fusion cross section below the barrier due to the transfer and breakup channel coupling, which strongly suggests that this channel is the 'doorway state' that explains the fusion barrier reduction observed in previous experiments. It was found that the {sup 4} He group fully dominates the total reaction cross section at the
Coulomb Thrusting Application Study
2006-01-20
this formation about the orbit radial direction. From this point on- wards, this will be referred to as the Coulomb tether regulation problem . These...m2 m2 (6.13) For the Coulomb tether regulation problem , L is taken as a sum of a constant reference length Lref and a small varying length δL...be noted that in the Coulomb tether regulation problem Lref is constant and the dif- ferential equation given in Eq. (6.13) is lin- earized by
Coulomb gauge ghost propagator and the Coulomb form factor
Quandt, M; Chimchinda, S; Reinhardt, H
2008-01-01
The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge on the lattice, using an improved gauge fixing scheme which includes the residual symmetry. This setting has been shown to be essential in order to explain the scaling violations in the instantaneous gluon propagator. We find that both the ghost propagator and the Coulomb potential are insensitive to the Gribov problem or the details of the residual gauge fixing, even if the Coulomb potential is evaluated from the A0--propagator instead of the Coulomb kernel. In particular, no signs of scaling violations could be found in either quantity, at least to well below the numerical accuracy where these violations were visible for the gluon propagator. The Coulomb potential from the A0-propagator is shown to be in qualitative agreement with the (formally equivalent) expression evaluated from the Coulomb kernel.
Coulomb gauge ghost propagator and the Coulomb form factor
Quandt, M.; Burgio, G.; Chimchinda, S.; Reinhardt, H.
The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge on the lattice, using an improved gauge fixing scheme which includes the residual symmetry. This setting has been shown to be essential in order to explain the scaling violations in the instantaneous gluon propagator. We find that both the ghost propagator and the Coulomb potential are insensitive to the Gribov problem or the details of the residual gauge fixing, even if the Coulomb potential is evaluated from the A0 -propagator instead of the Coulomb kernel. In particular, no signs of scaling violations could be found in either quantity, at least to well below the numerical accuracy where these violations were visible for the gluon propagator. The Coulomb potential from the A0 -propagator is shown to be in qualitative agreement with the (formally equivalent) expression evaluated from the Coulomb kernel.
Maj, Radoslaw
2009-01-01
The correlation function of two identical particles - pions or kaons - interacting via Coulomb potential is computed. The particles are emitted from an anisotropic particle's source of finite lifetime. In the case of pions, the effect of halo is taken into account as an additional particle's source of large spatial extension. The relativistic effects are discussed in detail. The Bowler-Sinyukov procedure to remove the Coulomb interaction is carefully tested. In the absence of halo the procedure is shown to work very well even for an extremely anisotropic source. When the halo is taken into account the free correlation function, which is extracted by means of the Bowler-Sinyukov procedure, is distorted at small relative momenta but the source parameters are still correctly reproduced.
Traceable Coulomb Blockade Thermometry
Hahtela, Ossi; Kemppinen, Antti; Meschke, Matthias; Prunnila, Mika; Gunnarsson, David; Roschier, Leif; Penttila, Jari; Pekola, Jukka
2016-01-01
We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods, the numerical fitting of the full conductance curve and measuring the height of the conductance dip yield almost identical results. The complete uncertainty analysis shows that the relative expanded uncertainty (k = 2) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 1 %. A good agreement within the measurement uncertainty is experimentally demonstrated between the Coulomb blockade thermometer and a superconducting reference point device that has been directly calibrated against the Provisional Low Temperature Scale of 2000.
Lieber, Michael
1989-06-01
It is something of a miracle that the nonrelativistic Schrodinger equation with a Coulomb potential can be solved for the wavefunction in exact analytic form. Even more miraculous is the result of Schwinger which enables the Green's function to be solved in closed form, for this is in effect, an infinite sum of wavefunction products. In the relativistic case too the wavefunction can be found in closed form, but as yet no such result for the Green's function has been found. This lecture provides a brief overview of the situation with an emphasis on the ``hidden symmetry'' which underlies the nonrelativisitic problem and its degenerate form which carries over to the relativistic case.
Traceable Coulomb blockade thermometry
Hahtela, O.; Mykkänen, E.; Kemppinen, A.; Meschke, M.; Prunnila, M.; Gunnarsson, D.; Roschier, L.; Penttilä, J.; Pekola, J.
2017-02-01
We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k = 1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5%. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39% to 0.67% from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.
Classical and quantum Coulomb crystals
Bonitz, M; Baumgartner, H; Henning, C; Filinov, A; Block, D; Arp, O; Piel, A; Kading, S; Ivanov, Y; Melzer, A; Fehske, H; Filinov, V
2008-01-01
Strong correlation effects in classical and quantum plasmas are discussed. In particular, Coulomb (Wigner) crystallization phenomena are reviewed focusing on one-component non-neutral plasmas in traps and on macroscopic two-component neutral plasmas. The conditions for crystal formation in terms of critical values of the coupling parameters and the distance fluctuations and the phase diagram of Coulomb crystals are discussed.
Coulomb blockade and Coulomb staircase behavior observed at room temperature
Uky Vivitasari, Pipit; Azuma, Yasuo; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka
2017-02-01
A single-electron transistor (SET) consists of source, drain, Coulomb island, and gate to modulate the number of electrons and control the current. For practical applications, it is important to operate a SET at room temperature. One proposal towards the ability to operate at room temperature is to decrease Coulomb island size down to a few nanometres. We investigate a SET using Sn-porphyrin (Sn-por) protected gold nanoparticles (AuNPs) with 1.4 nm in core diameter as a Coulomb island. The fabrication method of nanogap electrodes uses the combination of a top-down technique by electron beam lithography (EBL) and a bottom-up process through electroless gold plating (ELGP) as our group have described before. The electrical measurement was conducted at room temperature (300 K). From current-voltage (I d-V d) characteristics, we obtained clear Coulomb blockade phenomena together with a Coulomb staircase due to a Sn-por protected gold NP as a Coulomb island. Experimental results of I d-V d characteristics agree with a theoretical curve based on using the orthodox model. Clear dI d/dV d peaks are observed in the Coulomb staircase at 9 K which suggest the electron transports through excited energy levels of Au NPs. These results are a big step for obtaining SETs that can operate at room temperature.
Energy Technology Data Exchange (ETDEWEB)
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.)
Coulomb and nuclear effects in breakup and reaction cross sections
Descouvemont, P.; Canto, L. F.; Hussein, M. S.
2017-01-01
We use a three-body continuum discretized coupled channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li+208Pb . For breakup, we investigate various aspects, such as the role of the α +t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the Coulomb and nuclear breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest a third method which could be efficiently used to address convergence problems at large angular momentum. For reaction cross sections, interference effects are smaller, and the nuclear contribution is dominant above the Coulomb barrier. We also draw attention to different definitions of the reaction cross section which exist in the literature and which may induce small, but significant, differences in the numerical values.
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 and Nuclear Breakup at Low Energies: Scaling Laws
Directory of Open Access Journals (Sweden)
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.
The investigation of the Coulomb breakup effect on the 6-He elastic scattering
Energy Technology Data Exchange (ETDEWEB)
Kucuk, Yasemin; Boztosun, Ismail [Erciyes University, Department of Physics, Kayseri (Turkey); Keeley, Nicholas [Andrzej Soltan Institute, Department of Nuclear Reactions (Poland)
2009-07-01
The elastic scattering of the halo nuclei from the heavier target exhibits a different behavior from the standart Fresnel-type diffraction at energies near the Coulomb barrier. In this paper, we have performed the CDCC calculations for 6-He elastic scattering from the different targets to investigate the effect of the Coulomb breakup coupling and we have observed that the deviation from the standard diffraction behavior due to strong breakup coupling starts at around ZT= 60.
Coulomb interaction in multiple scattering theory
Ray, L.; Hoffmann, G. W.; Thaler, R. M.
1980-10-01
The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+208Pb elastic scattering and compared with experimental data. NUCLEAR REACTIONS 208Pb(p, p), E=0.8 GeV, Kerman, McManus, and Thaler, and Watson multiple scattering theories, Coulomb correction terms, high momentum transfer.
Energy Technology Data Exchange (ETDEWEB)
Aguiar, Carlos Eduardo Magalhaes de
1988-03-01
The enhancement of sub-barrier fusion observed in heavy ion collisions is studied in a liquid-drop model. It is shown that shape degrees of freedom related to neck formation play an important role in the fusion process, and increase the low energy fusion rates. The model predictions are in a quite satisfactory agreement with the experimental data, and major discrepancies seem to be found only for those systems where specific nuclear structure effects should also be considered. (author). 83 refs, 54 figs.
No confinement without Coulomb confinement
Zwanziger, D
2003-01-01
We compare the physical potential $V_D(R)$ of an external quark-antiquark pair in the representation $D$ of SU(N), to the color-Coulomb potential $V_{\\rm coul}(R)$ which is the instantaneous part of the 44-component of the gluon propagator in Coulomb gauge, $D_{44}(\\vx,t) = V_{\\rm coul}(|\\vx|) \\delta(t)$ + (non-instantaneous). We show that if $V_D(R)$ is confining, $\\lim_{R \\to \\infty}V_D(R) = + \\infty$, then the inequality $V_D(R) \\leq - C_D V_{\\rm coul}(R)$ holds asymptotically at large $R$, where $C_D > 0$ is the Casimir in the representation $D$. This implies that $ - V_{\\rm coul}(R)$ is also confining.
Diriken, J.; Stefanescu, I.; Balabanski, D.; Blasi, N.; Blazhev, A.; Bree, N.; Cederkaell, J.; Cocolios, T. E.; Davinson, T.; Eberth, J.; Ekstrom, A.; Fedorov, D. V.; Fedosseev, V. N.; Fraile, L. M.; Franchoo, S.; Georgiev, G.; Gladnishki, K.; Huyse, M.; Ivanov, O. V.; Ivanov, V. S.; Iwanicki, J.; Jolie, J.; Konstantinopoulos, T.; Kroell, Th.; Kruecken, R.; Koester, U.; Lagoyannis, A.; Lo Bianco, G.; Maierbeck, P.; Marsh, B. A.; Napiorkowski, P.; Patronis, N.; Pauwels, D.; Reiter, P.; Seliverstov, M.; Sletten, G.; Van de Walle, J.; Van Duppen, P.; Voulot, D.; Walters, W. B.; Warr, N.; Wenander, F.; Wrzosek, K.
2010-01-01
The B(E2; I-i -> I-f) values for transitions in Ga-71(31)40 and Ga-73(31)42 were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of Ga-71,Ga-73 at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were dete
Coulomb drag in quantum circuits
Levchenko, Alex; Kamenev, Alex
2008-01-01
We study drag effect in a system of two electrically isolated quantum point contacts (QPC), coupled by Coulomb interactions. Drag current exhibits maxima as a function of QPC gate voltages when the latter are tuned to the transitions between quantized conductance plateaus. In the linear regime this behavior is due to enhanced electron-hole asymmetry near an opening of a new conductance channel. In the non-linear regime the drag current is proportional to the shot noise of the driving circuit,...
Coulomb oscillations in three-layer graphene nanostructures
Energy Technology Data Exchange (ETDEWEB)
Guettinger, J; Stampfer, C; Molitor, F; Graf, D; Ihn, T; Ensslin, K [Solid State Physics Laboratory, ETH Zurich, 8093 Zurich (Switzerland)], E-mail: guettinj@phys.ethz.ch
2008-12-15
We present transport measurements on a tunable three-layer graphene single electron transistor (SET). The device consists of an etched three-layer graphene flake with two narrow constrictions separating the island from source and drain contacts. Three lateral graphene gates are used to electrostatically tune the device. An individual three-layer graphene constriction has been investigated separately showing a transport gap near the charge neutrality point. The graphene tunneling barriers show a strongly nonmonotonic coupling as a function of gate voltage indicating the presence of localized states in the constrictions. We show Coulomb oscillations and Coulomb diamond measurements proving the functionality of the graphene SET. A charging energy of {approx}0.6 meV is extracted.
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 dissociation of N-20,N-21
Roeder, 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.; 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; Gernhaeuser, Roman; Goebel, Kathrin; Golubev, Pavel; Diaz, D. Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Bjorn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knoebel, Ronja; Kroell, Thorsten; Kruecken, 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; del Rio Saez, Jose Sanchez; 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 in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a
Coulomb dissociation of N-20,N-21
Roeder, 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.; 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; Gernhaeuser, Roman; Goebel, Kathrin; Golubev, Pavel; Diaz, D. Gonzalez; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hakan; Jonson, Bjorn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knoebel, Ronja; Kroell, Thorsten; Kruecken, 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; del Rio Saez, Jose Sanchez; 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 in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N-20,N-21 are reported. Relativistic N-20,N-21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a
Coulomb Effects in Few-Body Reactions
Directory of Open Access Journals (Sweden)
Deltuva A.
2010-04-01
Full Text Available The method of screening and renormalization is used to include the Coulomb interaction between the charged particles in the momentum-space description of three- and four-body nuclear reactions. The necessity for the renormalization of the scattering amplitudes and the reliability of the method is demonstrated. The Coulomb eﬀect on observables is discussed.
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)
Coulomb string tension, asymptotic string tension, and the gluon chain
Greensite, Jeff; Szczepaniak, Adam P.
2015-02-01
We compute, via numerical simulations, the nonperturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.
Smooth models for the Coulomb potential
González-Espinoza, Cristina E; Karwowski, Jacek; Savin, Andreas
2016-01-01
Smooth model potentials with parameters selected to reproduce the spectrum of one-electron atoms are used to approximate the singular Coulomb potential. Even when the potentials do not mimic the Coulomb singularity, much of the spectrum is reproduced within the chemical accuracy. For the Hydrogen atom, the smooth approximations to the Coulomb potential are more accurate for higher angular momentum states. The transferability of the model potentials from an attractive interaction (Hydrogen atom) to a repulsive one (Harmonium and the uniform electron gas) is discussed.
Coulomb screening in linear coasting nucleosynthesis
Singh, Parminder
2015-01-01
We investigate the impact of coulomb screening on primordial nucleosynthesis in a universe having scale factor that evolves linearly with time. Coulomb screening affects primordial nucleosynthesis via enhancement of thermonuclear reaction rates. This enhancement is determined by the solving Poisson equation within the context of mean field theory (under appropriate conditions during the primordial nucleosynthesis). Using these results, we claim that the mean field estimates of coulomb screening hardly affect the predicted element abundances and nucleosynthesis parameters$, \\{\\eta_9,\\xi_e\\}$. The deviations from mean field estimates are also studied in detail by boosting genuine screening results with the screening parameter ($\\omega_s$). These deviations show negligible effect on the element abundances and on nucleosynthesis parameters. This work thus rules out the coulomb screening effects on primordial nucleosynthesis in slow evolving models and confirms that constraints in ref.[7] on nucleosynthesis parame...
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
DEFF Research Database (Denmark)
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan
2009-01-01
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 Distortion in the Inelastic Regime
Energy Technology Data Exchange (ETDEWEB)
Patricia Solvignon, Dave Gaskell, John Arrington
2009-09-01
The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.
Cavity QED experiments with ion Coulomb crystals
DEFF Research Database (Denmark)
Herskind, Peter Fønss; Dantan, Aurélien; Marler, Joan
2009-01-01
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....
Gaussian expansion approach to Coulomb breakup
Egami, T; Matsumoto, T; Iseri, Y; Kamimura, M; Yahiro, M
2004-01-01
An accurate treatment of Coulomb breakup reactions is presented by using both the Gaussian expansion method and the method of continuum discretized coupled channels. As $L^2$-type basis functions for describing Coulomb breakup processes, we take complex-range Gaussian functions, which form in good approximation a complete set in a large configuration space being important for the processes. Accuracy of the method is tested quantitatively for $^{8}{\\rm B}+^{58}$Ni scattering at 25.8 MeV.
Hakobyan, Tigran
2015-01-01
We define the integrable N-dimensional Calogero-Coulomb-Stark and two-center Calogero-Coulomb systems and construct their constants of motion via the Dunkl operators. Their Schroedinger equations decouple in parabolic and elliptic coordinates, respectively, into the set of three differential equations like for the Coulomb-Stark and two-center Coulomb problems.
Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals.
Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko
2007-04-14
The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine alpha-helix chains and three-dimensional diamond pieces.
Coulomb screening in graphene with topological defects
Chakraborty, Baishali; Gupta, Kumar S.; Sen, Siddhartha
2015-06-01
We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed.
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.
Leading order QCD in Coulomb gauge
Watson, Peter
2011-01-01
Coulomb gauge QCD in the first order formalism can be written in terms of a ghost-free, nonlocal action that ensures total color charge conservation via Gauss' law. Making an Ansatz whereby the nonlocal term (the Coulomb kernel) is replaced by its expectation value, the resulting Dyson-Schwinger equations can be derived. With a leading order truncation, these equations reduce to the gap equations for the static gluon and quark propagators obtained from a quasi-particle approximation to the canonical Hamiltonian approach. Moreover a connection to the heavy quark limit can be established, allowing an intuitive explanation for the charge constraint and infrared divergences.
Coulomb drag in coherent mesoscopic systems
DEFF Research Database (Denmark)
Mortensen, Niels Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2001-01-01
, such as the 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......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...
Coulomb drag in coherent mesoscopic systems
DEFF Research Database (Denmark)
Mortensen, 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 th......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...
A Coulomb-Like Off-Shell T-Matrix with the Correct Coulomb Phase Shift
Oryu, Shinsho; Watanabe, Takashi; Hiratsuka, Yasuhisa; Togawa, Yoshio
2017-03-01
We confirm the reliability of the well-known Coulomb renormalization method (CRM). It is found that the CRM is only available for a very-long-range screened Coulomb potential (SCP). However, such an SCP calculation in momentum space is considerably difficult because of the cancelation of significant digits. In contrast to the CRM, we propose a new method by using an on-shell equivalent SCP and the rest term. The two-potential theory with r-space is introduced, which defines fully the off-shell Coulomb amplitude.
Interatomic Coulombic decay in helium nanodroplets
DEFF Research Database (Denmark)
Shcherbinin, Mykola; Laforge, Aaron; Sharma, Vandana
2017-01-01
Interatomic Coulombic decay (ICD) is induced in helium nanodroplets by photoexciting the n=2 excited state of He+ using XUV synchrotron radiation. By recording multiple-coincidence electron and ion images we find that ICD occurs in various locations at the droplet surface, inside the surface region...
Coulomb drag between helical Luttinger liquids
Kainaris, N.; Gornyi, I. V.; Levchenko, A.; Polyakov, D. G.
2017-01-01
We theoretically study Coulomb drag between two helical edges with broken spin-rotational symmetry, such as would occur in two capacitively coupled quantum spin Hall insulators. For the helical edges, Coulomb drag is particularly interesting because it specifically probes the inelastic interactions that break the conductance quantization for a single edge. Using the kinetic equation formalism, supplemented by bosonization, we find that the drag resistivity ρD exhibits a nonmonotonic dependence on the temperature T . In the limit of low T ,ρD vanishes with decreasing T as a power law if intraedge interactions are not too strong. This is in stark contrast to Coulomb drag in conventional quantum wires, where ρD diverges at T →0 irrespective of the strength of repulsive interactions. Another unusual property of Coulomb drag between the helical edges concerns higher T for which, unlike in the Luttinger liquid model, drag is mediated by plasmons. The special type of plasmon-mediated drag can be viewed as a distinguishing feature of the helical liquid—because it requires peculiar umklapp scattering only available in the presence of a Dirac point in the electron spectrum.
Coulomb Logarithm, Version 1.0
Energy Technology Data Exchange (ETDEWEB)
2016-11-23
Clog is a library of charged particle stopping powers and related Coulomb logarithm processes in a plasma. The stopping power is a particularly useful quantity for plasma physics, as it measures the energy loss of per unit length of charged particle as it traverses a plasma. Clog's primary stopping power is the BPS (Brown-Preston-Singleton) theory.
Coulomb's Electrical Measurements. Experiment No. 14.
Devons, Samuel
Presented is information related to the life and work of Charles Coulomb as well as detailed notes of his measurements of the distribution of electricity on conductors. The two methods that he used (the large torsion balance, and the timing of "force" oscillations) are described. (SA)
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.
Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots
Keller, A. J.; Lim, J. S.; Sánchez, David; López, Rosa; Amasha, S.; Katine, J. A.; Shtrikman, Hadas; Goldhaber-Gordon, D.
2016-08-01
In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior.
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...
Coulomb crystallization of highly charged ions.
Schmöger, L; Versolato, O O; Schwarz, M; Kohnen, M; Windberger, A; Piest, B; Feuchtenbeiner, S; Pedregosa-Gutierrez, J; Leopold, T; Micke, P; Hansen, A K; Baumann, T M; Drewsen, M; Ullrich, J; Schmidt, P O; López-Urrutia, J R Crespo
2015-03-13
Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.
Photodetachment Microscope with Repulsive Coulomb Field
Golovinski, P A
2011-01-01
Investigation of electronic waves with high coherence in photodetachment of a negative ion gives a physical basis to develop the holographic electronic microscopy with high resolution. The interference pattern is considered in the framework of steady-state wave approach. In semiclassical approximation, an outgoing wave is described by the amplitude slowly varying along a trajectory. Quantum description of electron photodetachment from negative ion is formulated with the help of the inhomogeneous Schr\\"odinger equation. Its asymptotic solution is expressed in terms of the Green function that has exact expression for the homogeneous electric field and the Coulomb field. It is demonstrated that repulsive Coulomb field is effective for magnification of the interference pattern at a short distance from an ion. For the first time, as shown for this case, the interference pattern in asymptotic area can be calculated by means of global semiclassical approximation or, a little more roughly, by simple uniform field app...
Non-linear conductivity in Coulomb glasses
Energy Technology Data Exchange (ETDEWEB)
Voje, A.; Bergli, J. [Department of Physics, University of Oslo, P. O. Box 1048 Blindern, 0316 Oslo (Norway); Ortuno, M.; Somoza, A.M. [Departamento de Fisica - CIOyN, Universidad de Murcia, Murcia 30.071 (Spain); Caravaca, M.
2009-12-15
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 have compared results for two different models: a regular square lattice with only diagonal disorder and a random array of sites with diagonal and off-diagonal disorder. We have found that for moderate fields the logarithm of the conductivity is proportional to {radical}(E)/T{sup 2}, reproducing experimental results. We have also found that in the nonlinear regime the site occupancy in the Coulomb gap follows a Fermi-Dirac distribution with an effective temperature T{sub eff} higher than the phonon bath temperature T. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
Frictional Coulomb drag in strong magnetic fields
DEFF Research Database (Denmark)
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 eval......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 evaluated using diagrammatic techniques. The transresistivity is given by an integral over energy and momentum transfer weighted by the product of the screened interlayer interaction and the phase space for scattering events. We demonstrate, by a numerical analysis of the transresistivity, that for well...
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.
Module of System Galactica with Coulomb's Interaction
Directory of Open Access Journals (Sweden)
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 collision effects on linear Landau damping
Energy Technology Data Exchange (ETDEWEB)
Callen, J. D., E-mail: callen@engr.wisc.edu [University of Wisconsin, Madison, Wisconsin 53706-1609 (United States)
2014-05-15
Coulomb collisions at rate ν produce slightly probabilistic rather than fully deterministic charged particle trajectories in weakly collisional plasmas. Their diffusive velocity scattering effects on the response to a wave yield an effective collision rate ν{sub eff} ≫ ν and a narrow dissipative boundary layer for particles with velocities near the wave phase velocity. These dissipative effects produce temporal irreversibility for times t ≳ 1/ν{sub eff} during Landau damping of a small amplitude Langmuir wave.
Coulomb dissociation studies for astrophysical thermonuclear reactions
Energy Technology Data Exchange (ETDEWEB)
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
DEFF Research Database (Denmark)
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....
Coulomb drag in the mesoscopic regime
DEFF Research Database (Denmark)
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....
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...
Papp, Z
1996-01-01
We demonstrate the feasibility and efficiency of the Coulomb-Sturmian separable expansion method for generating accurate solutions of the Faddeev equations. Results obtained with this method are reported for several benchmark cases of bosonic and fermionic three-body systems. Correct bound-state results in agreement with the ones established in the literature are achieved for short-range interactions. We outline the formalism for the treatment of three-body Coulomb systems and present a bound-state calculation for a three-boson system interacting via Coulomb plus short-range forces. The corresponding result is in good agreement with the answer from a recent stochastic-variational-method calculation.
Coulomb excitation of {sup 8}Li
Energy Technology Data Exchange (ETDEWEB)
Assuncao, Marlete; Britos, Tatiane Nassar [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil). Dept. de Ciencias Exatas e da Terra; Descouvemont, Pierre [Universite Libre de Bruxelles (ULB), Brussels (Belgium). Physique Nucleaire Theorique et Physique Mathematique; Lepine-Szily, Alinka; Lichtenthaler Filho, Rubens; Barioni, Adriana; Silva, Diego Medeiros da; Pereira, Dirceu; Mendes Junior, Djalma Rosa; Pires, Kelly Cristina Cezaretto; Gasques, Leandro Romero; Morais, Maria Carmen; Added, Nemitala; Neto Faria, Pedro; Rec, Rafael [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear
2012-07-01
Full text: This work shows the Coulomb Excitation of {sup 8}Li on targets that have effectively behavior of Rutherford in angles and energies of interest for determining the value of the B(E2) electromagnetic transition. Theoretical aspects involved in this type of measure, known as COULEX [1], and some results in the literature [2-3] will be presented. Some problems with the targets and measurement system while performing an experiment on Coulomb Excitation of {sup 8}Li will be discussed: the energy resolution, background, possible contributions of the primary beam and also the excited states of the target near the region of elastic and inelastic peaks. They will be illustrated by measurements of the Coulomb Excitation of {sup 8}Li on targets of {sup 197}Au and {sup 208}Pb using the system RIBRAS(Brazilian Radioactive Ion Beam). In this case, the {sup 8}Li beam(T{sub 1/2} = 838 ms)is produced by {sup 9}Be({sup 7}Li;{sup 8} Li){sup 8}Be reaction from RIBRAS system which is installed at Instituto de Fisica of the Universidade de Sao Paulo. The primary {sup 7L}i beam is provided by Pelletron Accelerator. [1] K. Alder and A. Winther, Electromagnetic Excitation, North-Holland, New York, 1975; [2] P. Descouvemont and D. Baye, Phys. Letts. B 292, 235-238, 1992; [3] J. A. Brown, F. D. Becchetti, J. W. Jaenecke, K, Ashktorab, and D. A. Roberts, J. J. Kolata, R. J. Smith, and K. Lamkin, R. E. Warner, Phys. Rev. Letts., 66, 19, 1991; [4] R. J. Smith, J. J Kolata, K. Lamkin and A. Morsard, F. D. Becchetti, J. A. Brown, W. Z. Liu, J. W. Jaenecke, and D. A. Roberts, R. E. Warner, Phys. Rev. C, 43, 5, 1991. (author)
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.
Nanoplasmonic renormalization and enhancement of Coulomb interactions
Energy Technology Data Exchange (ETDEWEB)
Durach, M; Rusina, A; Stockman, M I [Department of Physics and Astronomy, Georgia State University, Atlanta, GA (United States); Klimov, V I [Chemistry Division, C-PCS, Los Alamos National Laboratory, Los Alamos, NM (United States)], E-mail: mstockman@gsu.edu
2008-10-15
In this paper, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing the dressed interaction explicitly for an important example of metal-dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Foerster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.
Coulomb drag in multiwall armchair carbon nanotubes
DEFF Research Database (Denmark)
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...
Nanoplasmonic renormalization and enhancement of Coulomb interactions
Durach, M.; Rusina, A.; Klimov, V. I.; Stockman, M. I.
2008-10-01
In this paper, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing the dressed interaction explicitly for an important example of metal-dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Förster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.
Coulombic dragging of molecular assemblies on nanotubes
Kral, Petr; Sint, Kyaw; Wang, Boyang
2009-03-01
We show by molecular dynamics simulations that polar molecules, ions and their assemblies could be Coulombically dragged on the surfaces of single-wall carbon and boron-nitride nanotubes by ionic solutions or individual ions moving inside the nanotubes [1,2]. We also briefly discuss highly selective ionic sieves based on graphene monolayers with nanopores [3]. These phenomena could be applied in molecular delivery, separation and desalination.[3pt] [1] Boyang Wang and Petr Kral, JACS 128, 15984 (2006). [0pt] [2] Boyang Wang and Petr Kral, Phys. Rev. Lett. 101, 046103 (2008). [0pt] [3] Kyaw Sint, Boyang Wang and Petr Kral, JACS, ASAP (2008).
Action principle for Coulomb collisions in plasmas
Hirvijoki, Eero
2016-09-01
An action principle for Coulomb collisions in plasmas is proposed. 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-MacDonald-Judd potentials. 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.
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.
Resonances in the two centers Coulomb system
Energy Technology Data Exchange (ETDEWEB)
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.
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.
New approach to folding with the Coulomb wave function
Energy Technology Data Exchange (ETDEWEB)
Blokhintsev, L. D.; Savin, D. A. [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Kadyrov, A. S. [Department of Physics, Astronomy and Medical Radiation Sciences, Curtin University, GPO Box U1987, Perth 6845 (Australia); Mukhamedzhanov, A. M. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States)
2015-05-15
Due to the long-range character of the Coulomb interaction theoretical description of low-energy nuclear reactions with charged particles still remains a formidable task. One way of dealing with the problem in an integral-equation approach is to employ a screened Coulomb potential. A general approach without screening requires folding of kernels of the integral equations with the Coulomb wave. A new method of folding a function with the Coulomb partial waves is presented. The partial-wave Coulomb function both in the configuration and momentum representations is written in the form of separable series. Each term of the series is represented as a product of a factor depending only on the Coulomb parameter and a function depending on the spatial variable in the configuration space and the momentum variable if the momentum representation is used. Using a trial function, the method is demonstrated to be efficient and reliable.
Coulomb effects in Fermi {beta} decay of {sup 74}Rb
Energy Technology Data Exchange (ETDEWEB)
Oinonen, M. [CERN, EP Div., Geneva (Switzerland)
2003-07-01
Coulomb effects in the {beta} decay of {sup 74}Rb have been studied at ISOLDE. The observation of the non-analog feeding in the {beta} decay allows for an estimation of the Coulomb mixing parameter {delta}{sub IM}{sup 1}. The analysis of the total Coulomb correction {delta}{sub C} is still hampered by the uncertainty in the decay energy. (orig.)
The proton-proton scattering without Coulomb force renormalization
Directory of Open Access Journals (Sweden)
Glöckle W.
2010-04-01
Full Text Available We demonstrate numerically that proton-proton (pp scattering observables can be determined directly by standard short range methods using a screened pp Coulomb force without renormalization. We numerically investigate solutions of the 3-dimensional Lippmann-Schwinger (LS equation for an exponentially screened Coulomb potential. For the limit of large screening radii we conﬁrm analytically predicted properties for oﬀ-shell, half-shell and on-shell elements of the Coulomb t-matrix.
Reconciling Coulomb breakup and neutron radiative capture
Capel, P.; Nollet, Y.
2017-07-01
The Coulomb-breakup method to extract the cross section for neutron radiative capture at astrophysical energies is analyzed in detail. In particular, its sensitivity to the description of the neutron-core continuum is ascertained. We consider the case of 14C(n ,γ )15C for which both the radiative capture at low energy and the Coulomb breakup of 15C into 14C+n on Pb at 68 MeV/nucleon have been measured with accuracy. We confirm the direct proportionality of the cross section for both reactions to the square of the asymptotic normalization constant of 15C observed by Summers and Nunes [Phys. Rev. C 78, 011601(R) (2008), 10.1103/PhysRevC.78.011601], but we also show that the 14C-n continuum plays a significant role in the calculations. Fortunately, the method proposed by Summers and Nunes can be improved to absorb that continuum dependence. We show that a more precise radiative-capture cross section can be extracted selecting the breakup data at forward angles and low 14C-n relative energies.
Coulomb excitation of radioactive {sup 79}Pb
Energy Technology Data Exchange (ETDEWEB)
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.
Transport Through a Coulomb Blockaded Majorana Nanowire
Zazunov, Alex; Egger, Reinhold; Yeyati, Alfredo Levy; Hützen, Roland; Braunecker, Bernd
In one-dimensional (1D) quantum wires with strong spin-orbit coupling and a Zeeman field, a superconducting substrate can induce zero-energy Majorana bound states located near the ends of the wire. We study electronic properties when such a wire is contacted by normal metallic or superconducting electrodes. A special attention is devoted to Coulomb blockade effects. We analyze the "Majorana single-charge transistor" (MSCT), i.e., a floating Majorana wire contacted by normal metallic source and drain contacts, where charging effects are important. We describe Coulomb oscillations in this system and predict that Majorana fermions could be unambiguously detected by the emergence of sideband peaks in the nonlinear differential conductance. We also study a superconducting variant of the MSCT setup with s-wave superconducting (instead of normal-conducting) leads. In the noninteracting case, we derive the exact current-phase relation (CPR) and find π-periodic behavior with negative critical current for weak tunnel couplings. Charging effects then cause the anomalous CPR I(\\varphi ) = Ic\\cos \\varphi, where the parity-sensitive critical current I c provides a signature for Majorana states.
Effect of Coulomb interaction on multi-electronwave packet dynamics
Energy Technology Data Exchange (ETDEWEB)
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.
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
Coulomb crystallization in classical and quantum systems
Bonitz, Michael
2007-11-01
Coulomb crystallization occurs in one-component plasmas when the average interaction energy exceeds the kinetic energy by about two orders of magnitude. A simple road to reach such strong coupling consists in using external confinement potentials the strength of which controls the density. This has been succsessfully realized with ions in traps and storage rings and also in dusty plasma. Recently a three-dimensional spherical confinement could be created [1] which allows to produce spherical dust crystals containing concentric shells. I will give an overview on our recent results for these ``Yukawa balls'' and compare them to experiments. The shell structure of these systems can be very well explained by using an isotropic statically screened pair interaction. Further, the thermodynamic properties of these systems, such as the radial density distribution are discussed based on an analytical theory [3]. I then will discuss Coulomb crystallization in trapped quantum systems, such as mesoscopic electron and electron hole plasmas in coupled layers [4,5]. These systems show a very rich correlation behavior, including liquid and solid like states and bound states (excitons, biexcitons) and their crystals. On the other hand, also collective quantum and spin effects are observed, including Bose-Einstein condensation and superfluidity of bound electron-hole pairs [4]. Finally, I consider Coulomb crystallization in two-component neutral plasmas in three dimensions. I discuss the necessary conditions for crystals of heavy charges to exist in the presence of a light component which typically is in the Fermi gas or liquid state. It can be shown that their exists a critical ratio of the masses of the species of the order of 80 [5] which is confirmed by Quantum Monte Carlo simulations [6]. Familiar examples are crystals of nuclei in the core of White dwarf stars, but the results also suggest the existence of other crystals, including proton or α-particle crystals in dense matter
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...
Gauge Theories on the Coulomb Branch
Schwarz, John H.
We construct the world-volume action of a probe D3-brane in AdS5 × S5 with N units of flux. It has the field content, symmetries, and dualities of the U(1) factor of 𝒩 = 4 U(N + 1) super Yang-Mills theory, spontaneously broken to U(N) × 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 they reproduce 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.
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.
Coulomb dissociation of light unstable nuclei
Energy Technology Data Exchange (ETDEWEB)
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.)
Ion Coulomb Crystals and Their Applications
Drewsen, Michael
The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged in the past two decades. While this document lacks figures and many specific references, it is the hope, not the text will stimulate the reader to dig deeper into one or more of the discussed subjects, and inspire her/him to think about new potential applications. A fully referenced journal article of essentially the same text can be found in Physica B 460, 105 (2015) [1].
Distorted Coulomb field of the scattered electron
Thomsen, H D; Andersen, K K; Lund, M D; Knudsen, H; Uggerhøj, E; Uggerhøj1, U I; Sona, P; Mangiarotti, A; Ketel, T J; Dizdar, A; Ballestrero, S; Connell, S H
2010-01-01
Experimental results for the radiation emission from ultrarelativistic electrons in targets of 0.03%–5% radiation length is presented. For the thinnest targets, the radiation emission is in accordance with the Bethe-Heitler formulation of bremsstrahlung, the target acting as a single scatterer. In this regime, the radiation intensity is proportional to the thickness. As the thickness increases, the distorted Coulomb field of the electron that is the result of the first scattering events, leads to a suppressed radiation emission per interaction, upon subsequent scattering events. In that case, the radiation intensity becomes proportional to a logarithmic function of the thickness, due to the suppression. Eventually, once the target becomes sufficiently thick, the entire radiation process becomes influenced by multiple scattering and the radiation intensity is again proportional to the thickness, but with a different constant of proportionality. The observed logarithmic thickness dependence of radiation inten...
Relativistic Coulomb scattering of spinless bosons
Garcia, M G
2015-01-01
The relativistic scattering of spin-0 bosons by spherically symmetric Coulomb fields is analyzed in detail with an arbitrary mixing of vector and scalar couplings. It is shown that the partial wave series reduces the scattering amplitude to the closed Rutherford formula exactly when the vector and scalar potentials have the same magnitude, and as an approximation for weak fields. The behavior of the scattering amplitude near the conditions that furnish its closed form is also discussed. Strong suppressions of the scattering amplitude when the vector and scalar potentials have the same magnitude are observed either for particles or antiparticles with low incident momentum. We point out that such strong suppressions might be relevant in the analysis of the scattering of fermions near the conditions for the spin and pseudospin symmetries. From the complex poles of the partial scattering amplitude the exact closed form of bound-state solutions for both particles and antiparticles with different scenarios for the ...
Pair distribution of ions in Coulomb lattice
Witt, H E D; Chugunov, A I; Baiko, D A; Yakovlev, D G
2003-01-01
The pair distribution function g(r) ident to g(x, y, z) and the radial pair distribution function g(r) of ions in body-centred-cubic and face-centred-cubic Coulomb crystals are calculated within the harmonic-lattice (HL) approximation in a wide temperature range, from the high-temperature classical limit (T >> h-bar w sub p , w sub p being the ion plasma frequency) to the low-temperature quantum limit (T || h-bar w sub p). In the classical limit, g(r) is also calculated by the Monte Carlo (MC) method. MC and HL results are demonstrated to be in good agreement. With decreasing T, the correlation peaks of g(r) and g(r) become narrower. At T || h-bar w sub p they become temperature independent (determined by zero-point ion vibrations).
Coulomb crystals in the magnetic field
Baiko, D A
2009-01-01
The body-centered cubic Coulomb crystal of ions in the presence of a uniform magnetic field is studied using the rigid electron background approximation. The phonon mode spectra are calculated for a wide range of magnetic field strengths and for several orientations of the field in the crystal. The phonon spectra are used to calculate the phonon contribution to the crystal energy, entropy, specific heat, Debye-Waller factor of ions, and the rms ion displacements from the lattice nodes for a broad range of densities, temperatures, chemical compositions, and magnetic fields. Strong magnetic field dramatically alters the properties of quantum crystals. The phonon specific heat increases by many orders of magnitude. The ion displacements from their equilibrium positions become strongly anisotropic. The results can be relevant for dusty plasmas, ion plasmas in Penning traps, and especially for the crust of magnetars (neutron stars with superstrong magnetic fields $B \\gtrsim 10^{14}$ G). The effect of the magnetic ...
Thermodynamic Functions of Magnetized Coulomb Crystals
Baiko, D A
2013-01-01
Free energy, internal energy, and specific heat for each of the three phonon spectrum branches of a magnetized Coulomb crystal with body-centered cubic lattice are calculated by numerical integration over the Brillouin zone in the range of magnetic fields $B$ and temperatures $T$, such that $0 \\le \\omega_{\\rm B}/\\omega_{\\rm p}\\le 10^3$ and $10^{-4} \\le T/T_{\\rm p} \\le 10^4$. In this case, $\\omega_{\\rm B}$ is the ion cyclotron frequency, $\\omega_{\\rm p}$ and $T_{\\rm p}$ are the ion plasma frequency and plasma temperature, respectively. The results of numerical calculations are approximated by simple analytical formulas. For illustration, these formulas are used to analyze the behavior of the heat capacity in the crust of a neutron star with strong magnetic field. Thermodynamic functions of magnetized neutron star crust are needed for modeling various observational phenomena in magnetars and high magnetic field pulsars.
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.
van der Holst, J. J. M.; van Oost, F. W. A.; Coehoorn, R.; Bobbert, P. A.
2011-02-01
We present the results of Monte Carlo simulations of transport of charge carriers of a single type in devices consisting of a disordered organic semiconductor sandwiched in between two electrodes. The simulations are based on hopping of carriers between sites with a Gaussian energetic distribution, which is either spatially uncorrelated or has a correlation based on interactions with randomly oriented dipoles. Coulomb interactions between the carriers are taken into account explicitly. For not too small injection barriers between the electrodes and the organic semiconductor, we find that the current obtained from the simulations can be described quite well by a one-dimensional drift-diffusion continuum model, which takes into account the long-range contributions of Coulomb interactions through the space-charge potential. For devices with low injection barriers, however, the simulations yield a considerably lower current than the continuum model. The reduction of the current for uncorrelated disorder is larger than for correlated disorder. By performing simulations in which the short-range contributions of the Coulomb interactions between the carriers are omitted, we demonstrate that the difference is caused by these short-range contributions. We can rationalize our results by analyzing the three-dimensional current distributions and the in-plane radial distribution function of the carriers resulting from the simulations for different injection barriers with and without taking into account these short-range contributions.
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
Coulomb distortion effects in deep-inelastic electron scattering
Co', Giampaolo; Heisenberg, Jochen
1987-11-01
The effects of the Coulomb distortion of the electron wave functions in the description of the electron scattering processes in the quasi-elastic region are discussed. A method to extract longitudinal and transverse response functions considering these effects is presented. While the transverse response function is remarkably affected by the Coulomb distortion, the values of the longitudinal response function are practically unchanged.
Plasmons in Dimensionally Mismatched Coulomb Coupled Graphene Systems
DEFF Research Database (Denmark)
Badalyan, S. M.; Shylau, A. A.; Jauho, Antti-Pekka
2017-01-01
We calculate the plasmon dispersion relation for Coulomb coupled metallic armchair graphene nanoribbons and doped monolayer graphene. The crossing of the plasmon curves, which occurs for uncoupled 1D and 2D systems, is split by the interlayer Coulomb coupling into a lower and an upper plasmon...
Antilocalization of Coulomb Blockade in a Ge-Si Nanowire
DEFF Research Database (Denmark)
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...
Spherical Calogero model with oscillator/Coulomb potential: classical case
Correa, Francisco; Lechtenfeld, Olaf; Nersessian, Armen
2016-01-01
We construct the Hamiltonians and symmetry generators of Calogero-oscillator and Calogero-Coulomb models on the N-dimensional sphere within the matrix-model reduction approach. Our method also produces the integrable Calogero-Coulomb-Stark model on the sphere and proves the integrability of the spin extensions of all these systems.
Quantum Dynamics of Biological Plasma in the External Coulomb Field
Lasukov, V. V.; Lasukova, T. V.; Lasukova, O. V.
2013-10-01
A quantum solution to the truncated Fisher-Kolmogorov-Petrovskii-Piskunov equation with Coulomb convection and linear diffusion is derived. The quantum radiation of biological systems, individual microorganisms (cells, bacteria), and dust plasma particles in the Coulomb field is studied using the foregoing solution.
Magneto-Coulomb effect in spin-valve devices
van der Molen, SJ; Tombros, N; van Wees, BJ
2006-01-01
We discuss the influence of the magneto-Coulomb effect (MCE) on the magnetoconductance of spin-valve devices. We show that the MCE can induce magnetoconductances of several percent or more, depending on the strength of the Coulomb blockade. Furthermore, the MCE-induced magnetoconductance changes sig
On the decoupling between classical Coulomb matter and radiation
Alastuey, Angel; Appel, Walter
2000-02-01
We consider a model of matter coupled to radiation at equilibrium. Matter is described by a one-component plasma of classical point charges with Coulomb interactions, while radiation is represented by the classical transverse potential vector in Coulomb gauge. Using a straightforward generalization of the Bohr-van Leeuwen theorem, we show that the equilibrium properties of classical Coulomb matter remain unaffected by the presence of the classical radiation. As far as the real world is concerned, this decoupling does survive at large distances where both matter and radiation can be treated classically. This invalidates all the large-distances predictions, for the charge correlations, of the so-called Darwin models which incorporate retarded electromagnetic interactions beyond the instantaneous Coulomb potential. A second related important consequence is that the first relativistic corrections to the Coulomb thermodynamical quantities must be evaluated within the theory of quantum electrodynamics at finite temperature, even in a weakly relativistic and almost classical regime for matter.
Influence of long-range Coulomb interaction in velocity map imaging
Barillot, T.; Brédy, R.; Celep, G.; Cohen, S.; Compagnon, I.; Concina, B.; Constant, E.; Danakas, S.; Kalaitzis, P.; Karras, G.; Lépine, F.; Loriot, V.; Marciniak, A.; Predelus-Renois, G.; Schindler, B.; Bordas, C.
2017-07-01
The standard velocity-map imaging (VMI) analysis relies on the simple approximation that the residual Coulomb field experienced by the photoelectron ejected from a neutral or ion system may be neglected. Under this almost universal approximation, the photoelectrons follow ballistic (parabolic) trajectories in the externally applied electric field, and the recorded image may be considered as a 2D projection of the initial photoelectron velocity distribution. There are, however, several circumstances where this approximation is not justified and the influence of long-range forces must absolutely be taken into account for the interpretation and analysis of the recorded images. The aim of this paper is to illustrate this influence by discussing two different situations involving isolated atoms or molecules where the analysis of experimental images cannot be performed without considering long-range Coulomb interactions. The first situation occurs when slow (meV) photoelectrons are photoionized from a neutral system and strongly interact with the attractive Coulomb potential of the residual ion. The result of this interaction is the formation of a more complex structure in the image, as well as the appearance of an intense glory at the center of the image. The second situation, observed also at low energy, occurs in the photodetachment from a multiply charged anion and it is characterized by the presence of a long-range repulsive potential. Then, while the standard VMI approximation is still valid, the very specific features exhibited by the recorded images can be explained only by taking into consideration tunnel detachment through the repulsive Coulomb barrier.
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.
Coulomb Breakup of Nucleus 6 Li on Ion 208Pb
Irgaziev, B. F.; ERGASHBAEV, H. T.
1998-01-01
In the framework of the three-body approach the A(a,bc)A Coulomb breakup has been investigated. The three-body Coulomb dynamic is taken into account to derive the expression for the reaction matrix element. The mechanism of the breakup includes the direct process and the excitation of resonance state of the particle a. The calculation of the triple differential cross section of the 208Pb(6Li, a d)208Pb Coulomb dissociation have been performed in the energy region Ea d < 1MeV. Cal...
Theory and simulation of strong correlations in quantum Coulomb systems
Bonitz, M; Filinov, A V; Golubnychiy, V O; Kremp, D; Gericke, D O; Murillo, M S; Filinov, V S; Fortov, V; Hoyer, W; Koch, S W
2003-01-01
Strong correlations in quantum Coulomb systems (QCS) are attracting increasing interest in many fields ranging from dense plasmas and semiconductors to metal clusters and ultracold trapped ions. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) or Coulomb crystals. We present first-principle simulation results of these systems including path integral Monte Carlo simulations of the equilibrium behaviour of dense hydrogen and electron-hole plasmas and molecular dynamics and quantum kinetic theory simulations of the nonequilibrium properties of QCS. Finally, we critically assess potential and limitations of the various methods in their application to Coulomb systems.
Coulomb crystals in the harmonic lattice approximation
Baiko, D A; De Witt, H E; Slattery, W L
2000-01-01
The dynamic structure factor ${\\tilde S}({\\bf k},\\omega)$ and the two-particle distribution function $g({\\bf r},t)$ of ions in a Coulomb crystal are obtained in a closed analytic form using the harmonic lattice (HL) approximation which takes into account all processes of multi-phonon excitation and absorption. The static radial two-particle distribution function $g(r)$ is calculated for classical ($T \\gtrsim \\hbar \\omega_p$, where $\\omega_p$ is the ion plasma frequency) and quantum ($T \\ll \\hbar \\omega_p$) body-centered cubic (bcc) crystals. The results for the classical crystal are in a very good agreement with extensive Monte Carlo (MC) calculations at $1.5 \\lesssim r/a calculated for classical and quantum bcc and face-centered cubic crystals, and anharmonic corrections are discussed. The inelastic part of the HL static structure factor $S''(k)$, averaged over orientations of wave-vector {\\bf k}, is shown to contain pronounced singularities at Bragg diffraction positions. The type of the singularities is di...
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
2016-07-21
One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed 'excitonic', promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the 'glue' that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.
Dirac Hamiltonian with superstrong Coulomb field
Voronov, B L; Tyutin, I V
2006-01-01
We consider the quantum-mechanical problem of a relativistic Dirac particle moving in the Coulomb field of a point charge $Ze$. In the literature, it is often declared that a quantum-mechanical description of such a system does not exist for charge values exceeding the so-called critical charge with Z=137 based on the fact that the standard expression for energy eigenvalues yields complex values at overcritical charges. We show that from the mathematical standpoint, there is no problem in defining a self-adjoint Hamiltonian for any value of charge. What is more, the transition through the critical charge does not lead to any qualitative changes in the mathematical description of the system. A specific feature of overcritical charges is the nonuniqueness of the self-adjoint Hamiltonian, but this nonuniqueness is also characteristic for charge values less than the critical one (and larger than the subcritical charge with Z=118). We present the spectra and (generalized) eigenfunctions for all self-adjoint Hamilt...
Relativistic Coulomb excitation of {sup 88}Kr
Energy Technology Data Exchange (ETDEWEB)
Moschner, Kevin; Blazhev, Andrey; Jolie, Jan; Warr, Nigel; Wendt, Andreas [IKP, Universitaet zu Koeln, 50937 Koeln (Germany); Collaboration: PreSPEC-Collaboration
2015-07-01
Within the scope of the PreSPEC campaign we performed a Coulomb-excitation experiment to determine absolute E2 transition strengths to 2{sup +} states in the radioactive nucleus {sup 88}Kr. The aim of our studies was to identify the one quadruple-phonon mixed-symmetry 2{sub MS}{sup +} state in order to extend our knowledge on these states to lighter N = 52 isotones and to track their evolution over different proton shells. The investigated ions were provided through projectile fission of a 650 MeV {sup 238}U beam on a primary target consisting of 0.6 g/cm{sup 2} {sup 9}Be and subsequent separation and identification of the reaction products via the FRS at GSI. The secondary target consisted of 0.4 g/cm{sup 2} {sup 197}Au. De-exciting γ radiation was detected by the PreSPEC array, consisting of 15 EUROBALL Cluster detectors. The Lund-York-Cologne-CAlorimeter LYCCA was used for particle identification after the secondary target. Absolute transition strengths of the transitions depopulating the 2{sup +}{sub 3} state in {sup 88}Kr which suggest the mixed symmetric character of this state are presented and discussed within the systematics of the N = 52 isotones.
Strong Coulomb Coupling in the Todorov Equation
Bawin, M.; Cugnon, J.; Sazdjian, H.
A positronium-like system with strong Coulomb coupling, considered in its pseudoscalar sector, is studied in the framework of relativistic quantum constraint dynamics with the Todorov choice for the potential. Case’s method of self-adjoint extension of singular potentials, which avoids explicit introduction of regularization cut-offs, is adopted. It is found that, as the coupling constant α increases, the bound state spectrum undergoes an abrupt change at the critical value α=αc=1/2. For α>αc, the mass spectrum displays, in addition to the existing states for α<αc, a new set of an infinite number of bound states concentrated in a narrow band starting at mass W=0; all the states have indefinitely oscillating wave functions near the origin. In the limit α→αc from above, the oscillations disappear and the narrow band of low-lying states shrinks to a single massless state with a mass gap with the rest of the spectrum. This state has the required properties to represent a Goldstone boson and to signal spontaneous breakdown of chiral symmetry.
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.
Coulomb gauge model for hidden charm tetraquarks
Xie, W.; Mo, L. Q.; Wang, Ping; Cotanch, Stephen R.
2013-08-01
The spectrum of tetraquark states with hidden charm is studied within an effective Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the (qcbar)1(cqbar)1 singlet-singlet (molecule) and the (qc)3(qbarcbar)3 triplet-triplet (diquark), for selected JPC states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with (qqbar)1 (ccbar1) states about half a GeV lighter than (qcbar)1(qbarc)1. The lightest 1++ and 1-- predictions are in agreement with the observed X (3872) and Y (4008) masses suggesting they are molecules with ωJ / ψ and ηhc, rather than D*Dbar* and DDbar, type structure, respectively. Similarly, the lightest isovector 1++ molecule, having a ρJ / ψ flavor composition, has mass near the recently observed charged Zc (3900) value. These flavor configurations are consistent with observed X, Y and Zc decays to ππJ / ψ.
The Coulomb Branch of 3d N= 4 Theories
Bullimore, Mathew; Dimofte, Tudor; Gaiotto, Davide
2017-09-01
We propose a construction for the quantum-corrected Coulomb branch of a general 3d gauge theory with N=4 supersymmetry, in terms of local coordinates associated with an abelianized theory. In a fixed complex structure, the holomorphic functions on the Coulomb branch are given by expectation values of chiral monopole operators. We construct the chiral ring of such operators, using equivariant integration over BPS moduli spaces. We also quantize the chiral ring, which corresponds to placing the 3d theory in a 2d Omega background. Then, by unifying all complex structures in a twistor space, we encode the full hyperkähler metric on the Coulomb branch. We verify our proposals in a multitude of examples, including SQCD and linear quiver gauge theories, whose Coulomb branches have alternative descriptions as solutions to Bogomolnyi and/or Nahm equations.
Modelos exactamente solubles en mecanica estadistica de sistemas de Coulomb
National Research Council Canada - National Science Library
Tellez, Gabriel
2013-01-01
Se presenta una revision de modelos exactamente solubles de fisica estadistica clasica en dos dimensiones de sistemas de Coulomb, que son sistemas compuestos por un gran numero de particulas cargadas electricamente...
The generalized Coulomb interactions for relativistic scalar bosons
Zarrinkamar, S.; Panahi, H.; Rezaei, M.
2016-07-01
Approximate analytical solutions of Duffin-Kemmer-Petiau (DKP) equation are obtained for the truncated Coulomb, generalized Cornell, Richardson and Song-Lin potentials via the quasi-exact analytical ansatz approach.
Thermodynamic properties of the magnetized Coulomb crystal lattices
Kozhberov, A. A.
2016-08-01
It is thought that Coulomb crystals of ions with hexagonal close-packed lattice may form in the crust of strongly-magnetized neutron stars (magnetars). In this work we are trying to verify this prediction assuming that the direction of the magnetic field corresponds to the minimum of the zero-point energy. We also continue a detailed study of vibration modes and thermodynamic properties of magnetized Coulomb crystals in a wide range of temperatures and magnetic fields. It is demonstrated that the total Helmholtz free energy of the body-centered cubic Coulomb crystal is always lower than that of the Coulomb crystal with hexagonal close-packed or face-centered cubic lattice, which casts doubt on the hypothesis above.
Simple field theoretical approach of Coulomb systems. Entropic effects
Energy Technology Data Exchange (ETDEWEB)
Di Caprio, D; Badiali, J P [Laboratory of Electrochemistry and Analytical Chemistry, University Paris 6, CNRS, ENSCP, BP 39, 4, Place Jussieu, 75252 Paris, Cedex 05 (France); Holovko, M [Institute for Condensed Matter Physics, National Academy of Sciences, 1 Svientsitskii Str, 79011 Lviv (Ukraine)], E-mail: dung.di_caprio@upmc.fr
2009-05-29
We discuss a new simple field theory approach of Coulomb systems. Using a description in terms of fields, we introduce in a new way the statistical degrees of freedom in relation to the quantum mechanics. We show by a series of examples that these fundamental entropic effects can help account for physical phenomena in relation to Coulomb systems whether symmetric or asymmetric in valence. Overall, this gives a new understanding of these systems.
COULOMB BLOCKADE OSCILLATIONS OF Si SINGLE-ELECTRON TRANSISTORS
Institute of Scientific and Technical Information of China (English)
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.
Coulomb sink effect on coarsening of metal nanostructures on surfaces
Institute of Scientific and Technical Information of China (English)
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.
Stable and Critical Noncohesive Coulomb Wedges: Exact Elastic Solutions
Wang, K.; Hu, Y.
2004-12-01
The theory of critically tapered Coulomb wedge has been successfully applied to model active fold-and-thrust belts or submarine accretionary prisms. Brittle mountain building is episodic in nature, controlled by changes in basal friction, erosion and sedimentation, and hydrogeology. Sediment accretion may be modulated by great subduction earthquakes. Between deformation episodes and/or during transition between compressional and extensional tectonics, the Coulomb wedges are stable (i.e., supercritical), to which the critical taper theory does not apply. In this work, we provide an exact elastic solution for stable wedges based on Airy stress functions. The stress equilibrium equation and definition of basal friction and basal and internal pore fluid pressure ratios are exactly the same as those used for Dahlen's [1984] exact solution for critical noncohesive Coulomb wedges, but internal friction μ becomes irrelevant. Given elastic - perfectly Coulomb-plastic rheology, for stresses in a wedge on the verge of Coulomb failure there must co-exist a critical taper solution involving μ and a unique equivalent elastic solution not involving μ . Our elastic solution precisely reduces to Dahlen's critical taper solution for critical conditions. For stable conditions, normal stress perpendicular to the surface slope σ z and shear stress τ xz are identical with those in a critical taper, but the slope-parallel normal stress is different. The elastic solution is also generally applicable to purely elastic wedges and useful for modeling geodetic observations. A stable noncohesive Coulomb wedge differs from a general elastic wedge in that its upper and lower surfaces stay at zero curvature during loading. Dahlen, F.A. (1984), Noncohesive critical Coulomb wedges: An exact solution, JGR, 89, 10,125-10,133.
Coulomb interaction in multiple scattering theory. [Kerman-McManus-Thaler and Watson theories
Energy Technology Data Exchange (ETDEWEB)
Ray, L.; Hoffmann, G.W.; Thaler, R.M.
1980-10-01
The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+/sup 208/Pb elastic scattering and compared with experimental data.
Efros-Shklovskii Coulomb gap in the absence of disorder
Rademaker, Louk; Mahmoudian, Samiyeh; Ralko, Arnaud; Fratini, Simone; Dobrosavljevic, Vladimir
2015-03-01
Certain models of frustrated electron systems have been shown to self-generate glassy behavior, in the absence of disorder. Possible candidate materials contain quarter-filled triangular lattices with long-range Coulomb interactions, as found in the θ-family of organic BEDT-TTF crystals. In disordered insulators with localized electronic states, the so-called Coulomb glass, the single particle excitation spectrum displays the well-known Efros-Shklovskii gap. The same excitation spectrum is investigated in a class of models that display self-generated electronic glassiness, showing pseudogap formation related to the Efros-Shklovskii Coulomb gap. Our study suggests universal characteristics of all electron glasses, regardless of disorder.
Elementary excitations and avalanches in the Coulomb glass
Palassini, Matteo; Goethe, Martin
2012-07-01
We study numerically the statistics of elementary excitations and charge avalanches in the classical Coulomb glass model of localized charges with unscreened Coulomb interaction and disorder. We compute the single-particle density of states with an energy minimization algorithm for systems of up to 1003 sites. The shape of the Coulomb gap is consistent with a power-law with exponent δ simeq 2.4 and marginally consistent with exponential behavior. The results are also compared with a recently proposed self-consistent approach. We then analyze the size distribution of the charge avalanches produced by a small perturbation of the system. We show that the distribution decays as a power law in the limit of large system size, and explain this behavior in terms of the elementary excitations. Similarities and differences with the scale-free avalanches observed in mean-field spin glasses are discussed.
Quasiparticle Gaps and Exciton Coulomb Energies in Si Nanoshells
Energy Technology Data Exchange (ETDEWEB)
Frey, K. [University of Illinois, Chicago; Idrobo Tapia, Juan C [ORNL; Tiago, Murilo L [ORNL; Reboredo, Fernando A [ORNL; Ogut, Serdar [University of Illinois, Chicago
2009-01-01
Quasiparticle gaps and exciton Coulomb energies of H-passivated spherical Si nanoshells are computed using rst principles SCF and GW methods. We nd that the quasiparticle gap of a nanoshell depends on both its inner radius R1 (weakly) and outer radius R2 (strongly). These dependences on R1 and R2 are mostly consistent with electrostatics of a metallic shell. We also nd that the unscreened Coulomb energy ECoul in Si nanoshells has a somewhat unexpected size dependence at xed outer radius R2: ECoul decreases as the nanoshell becomes more conning, contrary to what one would expect from quantum connement eects. We show that this is a consequence of an increase in the average electron-hole distance, giving rise to reduced exciton Coulomb energies in spite of the reduction in the conning nanoshell volume.
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.
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.
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.
Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study
DEFF Research Database (Denmark)
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...... effects for the Coulomb drag between different tubes due to selection rules combined with mismatching of wave vector and crystal angular momentum conservation near the Fermi level. This gives rise to orders of magnitude changes in R-21 and even the sign of R-21 can change depending on the chirality...
Plasmons in Dimensionally Mismatched Coulomb Coupled Graphene Systems
Badalyan, S. M.; Shylau, A. A.; Jauho, A. P.
2017-09-01
We calculate the plasmon dispersion relation for Coulomb coupled metallic armchair graphene nanoribbons and doped monolayer graphene. The crossing of the plasmon curves, which occurs for uncoupled 1D and 2D systems, is split by the interlayer Coulomb coupling into a lower and an upper plasmon branch. The upper branch exhibits an unusual behavior with end points at finite q . Accordingly, the structure factor shows either a single or a double peak behavior, depending on the plasmon wavelength. The new plasmon structure is relevant to recent experiments, its properties can be controlled by varying the system parameters and be used in plasmonic applications.
Spin and polarized current from Coulomb blockaded quantum dots.
Potok, R M; Folk, J A; Marcus, C M; Umansky, V; Hanson, M; Gossard, A C
2003-07-04
We report measurements of spin transitions for GaAs quantum dots in the Coulomb blockade regime and compare ground and excited state transport spectroscopy to direct measurements of the spin polarization of emitted current. Transport spectroscopy reveals both spin-increasing and spin-decreasing transitions, as well as higher-spin ground states, and allows g factors to be measured down to a single electron. The spin of emitted current in the Coulomb blockade regime, measured using spin-sensitive electron focusing, is found to be polarized along the direction of the applied magnetic field regardless of the ground state spin transition.
Correlated Coulomb drag in capacitively coupled quantum-dot structures
DEFF Research Database (Denmark)
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 (cotunneling....... 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...
An algebraic model of Coulomb scattering with spin
Energy Technology Data Exchange (ETDEWEB)
Levay, P. [School of Physics, University of Melbourne, Parkville (Australia); Department of Theoretical Physics, Institute of Physics, Technical University, Budapest (Hungary); Amos, K. [School of Physics, University of Melbourne, Parkville (Australia)
2001-05-11
A new matrix-valued realization for the so(3,1) algebra leads to a natural generalization of the Coulomb scattering problem of a particle with spin. The underlying su(2) gauge structure of this realization recasts the scattering problem into a familiar form, namely, the Coulomb scattering problem of a collection of dyons (particles having both electric and magnetic charges). Using this equivalent form and the results of Zwanziger for such systems, the scattering matrix can be calculated in the helicity formalism. (author)
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.
Vibrational motions in rotating nuclei studied by Coulomb excitations
Energy Technology Data Exchange (ETDEWEB)
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 repulsion in (TMTSF)2X and (TMTTF)2X
DEFF Research Database (Denmark)
Mortensen, Kell; Engler, E. M.
1985-01-01
On the basis of studies of transport properties of (TMTSF)2 X, (TMTTF)2X and their binary alloys the authors discuss the role of on-site Coulomb repulsion relative to the transfer integrals. In TMTTF-salts U/ta are believed to be large, resulting in a Hubbard gap, whereas U/ta in TMTSF-salts are ...
Canonical derivation of the Vlasov-Coulomb noncanonical Poisson structure
Energy Technology Data Exchange (ETDEWEB)
Kaufman, A.N.; Dewar, R.L.
1983-09-01
Starting from a Lagrangian formulation of the Vlasov-Coulomb system, canonical methods are used to define a Poisson structure for this system. Successive changes of representation then lead systematically to the noncanonical Lie-Poisson structure for functionals of the Vlasov distribution.
Coulomb and nuclear effects in breakup and reaction cross sections
Descouvemont, Pierre; Hussein, Mahir S
2016-01-01
We use a three-body Continuum Discretized Coupled Channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term, and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation, and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li + 208Pb. For breakup, we investigate various aspects, such as the role of the alpha + t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the 'Coulomb' and 'nuclear' breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest...
Fast Electron Repulsion Integrals for Molecular Coulomb Sturmians
DEFF Research Database (Denmark)
Avery, James Emil
2013-01-01
of 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...
Integrating over the Coulomb branch in N=2 gauge theory
Marino, Marcos; Moore, Gregory
1997-01-01
We review the relation of certain integrals over the Coulomb phase of $d=4$, N=2 SO(3) supersymmetric Yang-Mills theory with Donaldson-Witten theory. We describe a new way to write an important contact term in the theory and show how the integrals generalize to higher rank gauge groups.
Coulomb blockade and superuniversality of the theta angle
Burmistrov, I.S.; Pruisken, A.M.M.
2008-01-01
Based on the Ambegaokar-Eckern-Schön approach to the Coulomb blockade, we develop a complete quantum theory of the single electron transistor. We identify a previously unrecognized physical observable in the problem that, unlike the usual average charge on the island, is robustly quantized for any f
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...
Interpolating the Coulomb Phase of Little String Theory
Lin, Ying-Hsuan; Wang, Yifan; Yin, Xi
2015-01-01
We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. We also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.
Exchange Coulomb interaction in nanotubes: Dispersion of Langmuir waves
Andreev, P A
2015-01-01
Microscopic derivation of the Coulomb exchange interaction for electrons located on the nanotubes is presented. Our derivation is based on the many-particle quantum hydrodynamic method. We demonstrate the role of the curvature of the nanocylinders on the force of the exchange interaction. We calculate corresponding dispersion dependencies for electron oscillations on the nanotubes.
The Coulomb law and atomic levels in a superstrong B
Directory of Open Access Journals (Sweden)
Vysotsky M.I.
2014-04-01
Full Text Available The spectrum of atomic levels of hydrogen-like ions originating from the lowest Landau level in an external homogeneous superstrong magnetic field is obtained. The influence of the screening of the Coulomb potential on the values of critical nuclear charges is studied.
Application of Designer Polynomials to the Soft-Coulomb Potential
Weatherford, Charles; Wynn, Albert, III; Red, Eddie; Mathis, Clausell
2004-05-01
In a recent article [C.A. Weatherford, E. Red, A. Wynn III, International Journal of Quantum Chemistry 90, 1289-1294 (2002)], an algorithm was described whereby a synthetic weighted polynomial basis may be constructed which is adapted (designed) to a particular potential. It was applied therein to the Schroedinger equation with a coulomb potential in one dimension (-1/|x| ). A weighted polynomial basis with weight function w(x)=exp(-a|x|) was employed. It was observed that this potential had no even parity solutions - only odd parity solutions. The question arises as to the relationship of the solutions (eigenfunctions and eigenvalues) for this hard coulomb potential to the solutions for the soft coulomb potential (-1/ √x^2+b^2^1/2 ). In particular, since the soft coulomb potential is clearly expected to possess both even and odd parity solutions, how do these solutions behave as b->0 and thus what happens to the even solutions. This problem is deceptively difficult none of the standard basis sets produce a variational minimum as a function of 'a' for nonzero 'b'. This is apparently why this problem has never been done before. A new orthonormal basis was designed with weight function w(x)=exp(-a√x^2+b^2) which did produce a variational minimum for variable a and arbitrary fixed 'b'. The present paper describes these solutions and clearly indicates how they behave as b->0 .
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.
Plasmon-mediated Coulomb drag between graphene waveguides
DEFF Research Database (Denmark)
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...
Fusion below the Coulomb barrier (I); Fusion abajo de la barrera coulombiana (I)
Energy Technology Data Exchange (ETDEWEB)
Aguilera R, E.F.; Vega C, J.J.; Murillo, G.; Kolata, J.J. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)
1987-02-15
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 {sup 37}Cl + {sup 55}Ni, which presents the prospective behavior based on the one existent systematic is obtained. (Author)
Coulomb barrier and exchange interaction in dynamical two-electron systems
Gregoire, Maxwell; Lougovski, Pavel; Batelaan, Herman
2012-06-01
Recent electron sources can produce pulses containing multiple electrons that are confined both laterally and longitudinally. Given that the highest reported degeneracy for continuous sources of free electrons is about 10-4, it would be interesting to know the degeneracy for these pulsed sources. We previously studied one-dimensional two-electron degeneracy [1], and we now study three-dimensional two-electron degeneracy as a function of time. Our primary goal is to use this project as a necessary step to studying three-dimensional n-electron degeneracy. Our second goal is to develop a theory that predicts the outcome of Hasselbach's experiment demonstrating the Hanbury Brown-Twiss Effect [2] for free electrons.[4pt] [1] Lougovski P, and Batelaan H, Phys. Rev. A 84, 023417 (2011).[0pt] [2] Kiesel H, Renz A, and Hasselbach F, Nature. 418, 392-4 (2002).
Elastic scattering and transfer reactions for the system 7Be + 58Ni at Coulomb barrier energies
Mazzocco, M.; Torresi, D.; Acosta, L.; Boiano, A.; Boiano, C.; Glodariu, T.; Guglielmetti, A.; Keeley, N.; La Commara, M.; Lay, J. A.; Martel, I.; Mazzocchi, C.; Molini, P.; Parascandolo, C.; Parkar, V. V.; Pierroutsakou, D.; Romoli, M.; Rusek, K.; Sanchez-Benitez, A. M.; Sandoli, M.; Signorini, C.; Silvestri, R.; Soramel, F.; Strano, E.; Stroe, L.
2015-09-01
We investigated the reaction induced by the Radioactive Ion Beam 7Be on the closed proton shell nucleus 58Ni at 22.0 MeV bombarding energy. The 7Be beam was produced by means of the in-flight technique with the facility EXOTIC at INFN-LNL (Italy). Charged reaction products were mass and charge identified in a rather wide angular range and their energy distributions were analyzed to infer some information on the production mechanism. The relevance of direct processes, especially 3He- and 4He-stripping, as well as compound nucleus reactions is critically reviewed.
Reaction mechanism study of 7Li(7Li, 6He) reaction at above Coulomb barrier energies
Indian Academy of Sciences (India)
V V Parkar; V Jha; S Santra; B J Roy; K Ramachandran; A Shrivastava; K Mahata; A Chatterjee; S Kailas
2009-02-01
The elastic scattering and the 6He angular distributions were measured in 7Li + 7Li reaction at two energies, lab = 20 and 25 MeV. FRDWBA calculations have been performed to explain the measured 6He data. The calculations were very sensitive to the choice of the optical model potentials in entrance and exit channels. The one-step proton transfer was found to be the dominant reaction mechanism in 6He production.
Di Toro, M; Greco, V; Ferini, G; Rizzo, C; Rizzo, J; Baran, V; Gaitanos, T; Prassa, V; Wolter, H H; Zielinska-Pfabé, M
2007-01-01
Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this work we present a selection of reaction observables in dissipative collisions particularly sensitive to the isovector part of the interaction, i.e. to the symmetry term of the nuclear Equation of State (EoS). At low energies the behavior of the symmetry energy around saturation influences dissipation and fragment production mechanisms. We will first discuss the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation during the charge equilibration in fusion and deep-inelastic collisions. Important Iso-EOS effects are stressed. Reactions induced by unstable 132Sn beams appear to be very promising tools to test the sub-saturation Isovector EoS. New Isospin sensitive observables are also presented for deep-inelastic, fragmentation collisions and Isospin equilibration measurements (Imbalance Ratios). The high density symmetry term can be derive...
The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasting
Strader, Anne Elizabeth
I investigate how inclusion of static Coulomb stress changes, caused by tectonic loading and previous seismicity, contributes to the effectiveness and reliability of prospective earthquake forecasts. Several studies have shown that positive static Coulomb stress changes are associated with increased seismicity, relative to stress shadows. However, it is difficult to avoid bias when the learning and testing intervals are chosen retrospectively. I hypothesize that earthquake forecasts based on static Coulomb stress fields may improve upon existing earthquake forecasts based on historical seismicity. Within southern California, I have confirmed the aforementioned relationship between earthquake location and Coulomb stress change, but found no identifiable triggering threshold based on static Coulomb stress history at individual earthquake locations. I have also converted static Coulomb stress changes into spatially-varying earthquake rates by optimizing an index function and calculating probabilities of cells containing at least one earthquake based on Coulomb stress ranges. Inclusion of Coulomb stress effects gives an improvement in earthquake forecasts that is significant with 95% confidence, compared to smoothed seismicity null forecasts. Because of large uncertainties in Coulomb stress calculations near faults (and aftershock distributions), I combine static Coulomb stress and smoothed seismicity into a hybrid earthquake forecast. Evaluating such forecasts against those in which only Coulomb stress or smoothed seismicity determines earthquake rates indicates that Coulomb stress is more effective in the far field, whereas statistical seismology outperforms Coulomb stress near faults. Additionally, I test effects of receiver plane orientation, stress type (normal and shear components), and declustering receiver earthquakes. While static Coulomb stress shows significant potential in a prospective earthquake forecast, simplifying assumptions compromise its
Magnetic moment and lifetime measurements of Coulomb-excited states in 106Cd
Benczer-Koller, N.; Kumbartzki, G. J.; Speidel, K.-H.; Torres, D. A.; Robinson, S. J. Q.; Sharon, Y. Y.; Allmond, J. M.; Fallon, P.; Abramovic, I.; Bernstein, L. A.; Bevins, J. E.; Crawford, H. L.; Guevara, Z. E.; Hurst, A. M.; Kirsch, L.; Laplace, T. A.; Lo, A.; Matthews, E. F.; Mayers, I.; Phair, L. W.; Ramirez, F.; Wiens, A.
2016-09-01
Background: The Cd isotopes are well studied, but experimental data for the rare isotopes are sparse. At energies above the Coulomb barrier, higher states become accessible. Purpose: Remeasure and supplement existing lifetimes and magnetic moments of low-lying states in 106Cd. Methods: In an inverse kinematics reaction, a 106Cd beam impinging on a 12C target was used to Coulomb excite the projectiles. The high recoil velocities provide a unique opportunity to measure g factors with the transient-field technique and to determine lifetimes from lineshapes by using the Doppler-shift-attenuation method. Large-scale shell-model calculations were carried out for 106Cd. Results: The g factors of the 21+ and 41+ states in 106Cd were measured to be g (21+)=+0.398 (22 ) and g (41+)=+0.23 (5 ) . A lineshape analysis yielded lifetimes in disagreement with published values. The new results are τ (106Cd;21+)=7.0 (3 )ps and τ (106Cd;41+)=2.5 (2 )ps . The mean life τ (106Cd;22+)=0.28 (2 )ps was determined from the fully-Doppler-shifted γ line. Mean lives of τ (106Cd;43+)=1.1 (1 )ps and τ (106Cd;31-)=0.16 (1 )ps were determined for the first time. Conclusions: The newly measured g (41+) of 106Cd is found to be only 59% of the g (21+) . This difference cannot be explained by either shell-model or collective-model calculations.
Coulomb Artifacts and Bottomonium Hyperfine Splitting in Lattice NRQCD
Liu, Tao; Rayyan, Ahmed
2016-01-01
We study the role of the lattice artifacts associated with the Coulomb binding effects in the analysis of the heavy quarkonium within lattice NRQCD. We find that a "na\\"ive" perturbative matching generates spurious linear Coulomb artifacts, which result in a large systematic error in the lattice predictions for the heavy quarkonium spectrum. This effect is responsible, in particular, for the discrepancy between the recent determinations of the bottomonium hyperfine splitting in the radiatively improved lattice NRQCD [1, 2]. We show that the correct matching procedure which provides full control over discretization errors is based on the asymptotic expansion of the lattice theory about the continuum limit, which gives $M_{\\Upsilon(1S)}-M_{\\eta_b(1S)}=52.9\\pm 5.5~{\\rm MeV}$ [1].
Glassy Dynamics in Geometrically Frustrated Coulomb Liquids without Disorder
Mahmoudian, Samiyeh; Rademaker, Louk; Ralko, Arnaud; Fratini, Simone; Dobrosavljević, Vladimir
2015-07-01
We show that introducing long-range Coulomb interactions immediately lifts the massive ground state degeneracy induced by geometric frustration for electrons on quarter-filled triangular lattices in the classical limit. Important consequences include the stabilization of a stripe-ordered crystalline (global) ground state, but also the emergence of very many low-lying metastable states with amorphous "stripe-glass" spatial structures. Melting of the stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures, showing remarkably slow (viscous) dynamics, with very long relaxation times growing in Arrhenius fashion upon cooling, as typical of strong glass formers. On shorter time scales, the system falls out of equilibrium and displays the aging phenomena characteristic of supercooled liquids above the glass transition. Our results show remarkable similarity with the recent observations of charge-glass behavior in ultraclean triangular organic materials of the θ -(BEDT -TTF )2 family.
Structure of light neutron-rich nuclei through Coulomb dissociation
Indian Academy of Sciences (India)
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.
Back to epicycles - relativistic Coulomb systems in velocity space
Ben-Ya'acov, Uri
2017-05-01
The study of relativistic Coulomb systems in velocity space is prompted by the fact that the study of Newtonian Kepler/Coulomb systems in velocity space, although less familiar than the analytic solutions in ordinary space, provides a much simpler (also more elegant) method. The simplicity and elegance of the velocity-space method derives from the linearity of the velocity equation, which is the unique feature of 1/r interactions for Newtonian and relativistic systems alike. The various types of possible trajectories are presented, their properties deduced from the orbits in velocity space, accompanied with illustrations. In particular, it is found that the orbits traversed in the relativistic velocity space (which is hyperbolic (H 3) rather than Euclidean) are epicyclic - circles whose centres also rotate - thus the title. Dedicated to the memory of J. D. Bekenstein - physicist, teacher and human
Direct simulation Monte Carlo schemes for Coulomb interactions in plasmas
Dimarco, Giacomo; Pareschi, Lorenzo
2010-01-01
We consider the development of Monte Carlo schemes for molecules with Coulomb interactions. We generalize the classic algorithms of Bird and Nanbu-Babovsky for rarefied gas dynamics to the Coulomb case thanks to the approximation introduced by Bobylev and Nanbu (Theory of collision algorithms for gases and plasmas based on the Boltzmann equation and the Landau-Fokker-Planck equation, Physical Review E, Vol. 61, 2000). Thus, instead of considering the original Boltzmann collision operator, the schemes are constructed through the use of an approximated Boltzmann operator. With the above choice larger time steps are possible in simulations; moreover the expensive acceptance-rejection procedure for collisions is avoided and every particle collides. Error analysis and comparisons with the original Bobylev-Nanbu (BN) scheme are performed. The numerical results show agreement with the theoretical convergence rate of the approximated Boltzmann operator and the better performance of Bird-type schemes with respect to t...
Structural phase transitions and topological defects in ion Coulomb crystals
Energy Technology Data Exchange (ETDEWEB)
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 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.
Structural phase transitions and topological defects in ion Coulomb crystals
Energy Technology Data Exchange (ETDEWEB)
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.
Time-resolved studies of interatomic Coulombic decay
Energy Technology Data Exchange (ETDEWEB)
Frühling, U. [Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Trinter, F. [Institut für Kernphysik, Goethe Universität, Max-von-Laue-Str.1, 60438 Frankfurt (Germany); Karimi, F. [Institut für Experimentalphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Center for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Williams, J.B. [Institut für Kernphysik, Goethe Universität, Max-von-Laue-Str.1, 60438 Frankfurt (Germany); Jahnke, T., E-mail: jahnke@atom.uni-frankfurt.de [Institut für Kernphysik, Goethe Universität, Max-von-Laue-Str.1, 60438 Frankfurt (Germany)
2015-10-15
Interatomic Coulombic decay (ICD) is a decay mechanism occurring in loosely bound matter, e.g. in systems bound by van der Waals-forces or hydrogen bonds. In many such cases the decay time is similar to the time scale of nuclear motion during the decay. As the efficiency of ICD strongly depends on the internuclear distance of the atoms or molecules involved in the decay, an overall non-trivial temporal decay behavior arises. The progress of examining the time-domain aspects of interatomic Coulombic decay is summarized in this short topical review with a special emphasis on experiments that are now feasible due to the developments of free-electron lasers.
Effect of Coulomb Screening Length on Nuclear Pasta Simulations
Alcain, P N; Nichols, J I; Dorso, C O
2013-01-01
We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semi-classical molecular dynamics model, studying isospin symmetric matter at sub-saturation densities and low temperatures. The electrostatic interaction between protons interaction is included in the form of a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the non-homogeneous nuclear structures known as ``nuclear pasta''. As the screening length increases, we can a transition from a one-per-cell pasta regime (due exclusively to finite size effects) to a more appealing multiple pasta per simulation box. This shows qualitative difference in the structure of neutron star matter at low temperatures, and therefore, special caution should be taken when the screening length is estimated for numerical simulat...
Low-energy Coulomb excitation of Sr,9896 beams
Clément, E.; Zielińska, M.; Péru, S.; Goutte, H.; Hilaire, S.; Görgen, A.; Korten, W.; Doherty, D. T.; Bastin, B.; Bauer, C.; Blazhev, A.; Bree, N.; Bruyneel, B.; Butler, P. A.; Butterworth, J.; Cederkäll, J.; Delahaye, P.; Dijon, A.; Ekström, A.; Fitzpatrick, C.; Fransen, C.; Georgiev, G.; Gernhäuser, R.; Hess, H.; Iwanicki, J.; Jenkins, D. G.; Larsen, A. C.; Ljungvall, J.; Lutter, R.; Marley, P.; Moschner, K.; Napiorkowski, P. J.; Pakarinen, J.; Petts, A.; Reiter, P.; Renstrøm, T.; Seidlitz, M.; Siebeck, B.; Siem, S.; Sotty, C.; Srebrny, J.; Stefanescu, I.; Tveten, G. M.; Van de Walle, J.; Vermeulen, M.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.; De Witte, H.; Wrzosek-Lipska, K.
2016-11-01
The structure of neutron-rich Sr,9896 nuclei was investigated by low-energy safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN, with the MINIBALL spectrometer. A rich set of transitional and diagonal E 2 matrix elements, including those for non-yrast structures, has been extracted from the differential Coulomb-excitation cross sections. The results support the scenario of a shape transition at N =60 , giving rise to the coexistence of a highly deformed prolate and a spherical configuration in 98Sr, and are compared to predictions from several theoretical calculations. The experimental data suggest a significant contribution of the triaxal degree of freedom in the ground state of both isotopes. In addition, experimental information on low-lying states in 98Rb has been obtained.
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.
Confining Dyon-Anti-Dyon Coulomb Liquid Model I
Liu, Yizhuang; Zahed, Ismail
2015-01-01
We revisit the dyon-anti-dyon liquid model for the Yang-Mills confining vacuum discussed by Diakonov and Petrov, by retaining the effects of the classical interactions mediated by the streamline between the dyons and anti-dyons. In the SU(2) case the model describes a 4-component strongly interacting Coulomb liquid in the center symmetric phase. We show that in the linearized screening approximation the streamline interactions yield Debye-Huckel type corrections to the bulk parameters such as the pressure and densities, but do not alter significantly the large distance behavior of the correlation functions in leading order. The static scalar and charged structure factors are consistent with a plasma of a dyon-anti-dyon liquid with a Coulomb parameter $\\Gamma_{D\\bar D}\\approx 1$ in the dyon-anti-dyon channel. Heavy quarks are still linearly confined and the large spatial Wilson loops still exhibit area laws in leading order.
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...
Applicability of the molecular dynamics technique to a Coulomb plasma
Energy Technology Data Exchange (ETDEWEB)
Zhidkov, A.G.; Galeev, R.Kh.
1993-09-01
In the present work, we report the calculations of the local Lyapunov parameter which determines the nature of the motion for a system of n particles interacting according to Coulomb`s law. These calculations have been performed for the most probable states of a fully ionized plasma, and they were performed using a Microvax-3 computer with the NAG(FO2) program package for a plasma consisting of particles with the same mass and for a fully ionized hydrogen plasma. The particle coordinates were prescribed as a uniformly distributed set of random numbers obtained using the NAG(GO5) routine. Results for the Lyapunov parameter are presented, and it is shown that the values of the parameter increases sharply as a function of particle number up to n=100 and then saturate. This latter observation is attributed to shielding, related to Debye effects.
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.
Interplay of Coulomb interaction and spin-orbit coupling
Bünemann, Jörg; Linneweber, Thorben; Löw, Ute; Anders, Frithjof B.; Gebhard, Florian
2016-07-01
We employ the Gutzwiller variational approach to investigate the interplay of Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model. Already in the paramagnetic phase we find a substantial renormalization of the spin-orbit coupling that enters the effective single-particle Hamiltonian for the quasiparticles. Only close to half band-filling and for sizable Coulomb interaction do we observe clear signatures of Hund's atomic rules for spin, orbital, and total angular momentum. For a finite local Hund's rule exchange interaction we find a ferromagnetically ordered state. The spin-orbit coupling considerably reduces the size of the ordered moment, it generates a small ordered orbital moment, and it induces a magnetic anisotropy. To investigate the magnetic anisotropy energy, we use an external magnetic field that tilts the magnetic moment away from the easy axis (1 ,1 ,1 ) .
Coulomb Traps and Charge Transport in Molecular Solids
Scher, Harvey
2000-03-01
A major result of experimental studies of a diverse assortment of disordered molecular solids is the observation of a common pattern in the charge transport properties. The transport ranges from charge transfer between molecules doped in an inert polymer to motion along the silicon backbone of polysilylenes. The pattern is the unusual combination of Poole Frenkel-like electric field dependence and non-Arrhenius temperature dependence of the mobility. The latter feature has been especially puzzling. We study the drift mobility of a molecular polaron in the presence of an applied field and Coulomb traps. The model is based on one previously developed for geminate recombination of photogenerated charge carriers. The key electric field and temperature dependencies of the mobility measurements are well reproduced by this model. Our conclusion is that this nearly universal transport behavior arises from competition between rates of polaron trapping and release from a very low density of Coulomb traps.
Renormalization group analysis of graphene with a supercritical Coulomb impurity
Nishida, Yusuke
2016-08-01
We develop a field-theoretic 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.
An entropic form for NLFP with coulombic-like potential
Energy Technology Data Exchange (ETDEWEB)
Grassi, A., E-mail: agrassi@unict.it [Dipartimento di Scienze del Farmaco, Università di Catania, V.le A. Doria 6, 95125 Catania (Italy)
2012-01-30
Here it is proposed a new entropy form for which it is possible to obtain a stationary solution of the Non-Linear Fokker–Planck equation (NLFP) with coulombic-like potentials. The general properties of this new entropy form are shown and the results are compared with those obtained by other entropy forms. Finally, the behavior of the stationary solution in presence of two point charges is also shown. -- Highlights: ► In this Letter we have proposed a new form of entropy. ► Starting from this new entropy form a Non-Linear Fokker–Planck equation has been derived. ► The stationary solution of the Non-Linear Fokker–Planck equation is obtained by using an external coulombic-like potential. ► A comparison with other forms of entropies has been proposed in the case of a single or two point charges.
Coulomb-Born-Oppenheimer approximation in Ps-H scattering
Indian Academy of Sciences (India)
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.
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.
Evaluation of Coulomb Energy Difference for Light Mirror Nuclei Using Slater—Type Orbitals
Institute of Scientific and Technical Information of China (English)
F.Oner; R.A.Mamedoy
2002-01-01
Behavior of the Coulomb energy difference for light nuclei is explained in terms of the different values of the average Coulomb interaction between two particles.Coulomb energy difference according to shell model of light mirror nuclei in the Coulomb and exchange integrals in the formula can be explained with exponential-type wavefunctions.In this study,using the one-center expansion of exponential-type wavefunctions in terms of Slater-type orbitals with the same center,we derived formula for Coulomb energy difference of light mirror nuclei.
Evaluation of Coulomb Energy Difference for Light Mirror Nuclei Using Slater-Type Orbitals
Institute of Scientific and Technical Information of China (English)
F. Oner; B.A. Mainedov
2002-01-01
Behavior of the Coulomb energy difference for light nuclei is explained in terms of the different values of theaverage Coulomb interaction between two particles. Coulomb energy difference according to shell model of light mirrornuclei in the Coulomb and exchange integrals in the formula can be explained with exponential-type wavefunctions. Inthis study, using the one-center expansion of exponential-type wavcfunctions in terms of Slater-type orbitals with thesame center, we derived formula for Coulomb energy difference of light mirror mulei.
Coulomb Interactions and Mesoscopic Effects in Carbon Nanotubes
Kane, Charlie; Balents, Leon; Fisher, Matthew
1997-01-01
We argue that long-range Coulomb forces convert an isolated (N,N) armchair carbon nanotube into a strongly-renormalized *Luttinger liquid*. At high temperatures, we find anomalous temperature dependences for the interaction and impurity contributions to the resistivity, and similar power-law dependences for the local tunneling density of states. At low temperatures, the nanotube exhibits spin-charge separation, visible as an extra energy scale in the discrete tunneling density of states (for ...
Molecular Dynamics Simulation of Shear Moduli for Coulomb Crystals
Horowitz, C J
2008-01-01
Torsional (shear) oscillations of neutron stars may have been observed in quasiperiodic oscillations of Magnetar Giant Flares. The frequencies of these modes depend on the shear modulus of neutron star crust. We calculate the shear modulus of Coulomb crystals from molecular dynamics simulations. We find that electron screening reduces the shear modulus by about 10% compared to previous Ogata et al. results. Our MD simulations can be extended to calculate the effects of impurities and or polycrystalline structures on the shear modulus.
PT-invariant one-dimensional Coulomb problem
Sinha, A K; Sinha, Anjana; Roychoudhury, Rajkumar
2002-01-01
The one-dimensional Coulomb-like potential with a real coupling constant beta, and a centrifugal-like core of strength G = alpha^2 - {1/4}, viz. V(x) = {alpha^2 - (1/4)}/{(x-ic)^2} + beta/|x-ic|, is discussed in the framework of PT-symmetry. The PT-invariant exactly solvable model so formed, is found to admit a double set of real and discrete energies, numbered by a quasi-parity q = +/- 1.
Coulomb excitation of 144,146,148,150Nd
Ahmad, A.; Bomar, G.; Crowell, H.; Hamilton, J. H.; Kawakami, H.; Maguire, C. F.; Nettles, W. G.; Piercey, R. B.; Ramayya, A. V.; Soundranayagam, R.; Ronningen, R. M.; Scholten, O.; Stelson, P. H.
1988-01-01
Coulomb excitation of 144,146,148,1605060Nd by 10.5 and 11 MeV alpha particles was studied by magnetic analysis of particles scattered into 150°. Values of B(E20+-->2+) for the 2+ states at 696, 454, 302, and 130 keV are 0.58(1), 0.78(1), 1.390(20), and 2.816(35) e2b2, respectively. For 148,150Nd, v
Coulombic potentials in the semi-classical limit
Energy Technology Data Exchange (ETDEWEB)
Chantelau, K. (Technische Univ. Berlin (Germany, F.R.). Fachbereich 3 - Mathematik)
1990-05-01
This paper is devoted to Schroedinger operators in two dimensions with singular (Coulombic) potentials. We investigate the behaviour of the eigenvalues at the bottom of the spectrum in the semi-classical limit. To overcome the difficulties due to the singularities, we use some kind of generalisation of the Levi-Civita transform. After this regularisation, we apply the theory of Helffer and Sjoestrand to get the full asymptotics for the eigenvalues. (orig.).
Coulomb Sturmians as a basis for molecular calculations
DEFF Research Database (Denmark)
Avery, John Scales; Avery, James Emil
2012-01-01
Almost all modern quantum chemistry programs use Gaussian basis sets even though Gaussians cannot accurately represent the cusp at atomic nuclei, nor can they represent the slow decay of the wave function at large distances. The reason that Gaussians dominate quantum chemistry today is the great...... of hyperspherical harmonics. For the remaining many-centre integrals, Coulomb Sturmians are shown to have advantages over other ETOs. Pilot calculations are performed on N-electron molecules using the Generalized Sturmian Method....
Electron interactions in graphene through an effective Coulomb potential
Rodrigues, Joao N. B.; Adam, Shaffique
A recent numerical work [H.-K. Tang et al, PRL 115, 186602 (2015)] considering graphene's π-electrons interacting through an effective Coulomb potential that is finite at short-distances, stressed the importance of the sp2 -electrons in determining the semimetal to Mott insulator phase transition in graphene. Some years ago, I. F. Herbut [PRL 97, 146401 (2006)] studied such a transition by mapping graphene's π-electrons into a Gross-Neveu model. From a different perspective, D. T. Son [PRB 75, 235423 (2007)] put the emphasis on the long-range interactions by modelling graphene as Dirac fermions interacting through a bare Coulomb potential. Here we build on these works and explore the phase diagram of Dirac fermions interacting through an effective Coulomb-like potential screened at short-distances. The interaction potential used allows for analytic results that controllably switch between the two perspectives above. This work was supported by the Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM medium-sized centre program) and by the Singapore Ministry of Education and Yale-NUS College (R-607-265-01312).
The EMC effect of Nuclear Matter with Coulomb Corrections
Li, Shujie; Solvignon, Patricia; Arrington, John; Gaskell, Dave
2016-09-01
Extraction of the EMC effect for nuclear matter is of great interest since it allows comparison to theoretical calculations in a regime where ``exact'' nuclear wave functions can be used. Earlier extractions from (e,e') cross sections ignored the contribution of the Coulomb distortion, which can be approximated as an electron energy shift on the order of MeV. Though small, this shift can cause a noticeable change in cross sections in certain kinematic regimes. In this study, we applied Coulomb corrections on the per-nucleon ratios from the published SLAC E139 data and preliminary JLAB E03-103 data. I will show preliminary results for an extrapolation of the EMC ratios from finite nuclei to symmetric nuclear matter, including Coulomb Corrections and examining the sensitivity to different approximations for the nuclear density. The data from two experiments will also be combined to study the nuclear dependence of R =σL /σT . Supported in part by DOE Grant No. DE-AC05-06OR23177, No. DE-AC02-06CH11357, and No. DE-SC0014168.
Implosive Interatomic Coulombic decay in the simplest molecular anion
Greene, Chris H.; Perez-Rios, Jesus; Slipchenko, Lyudmila
2016-05-01
Interatomic Coulombic decay (ICD) has been extensively studied in different systems: from diatomic systems such as He2 up to more complex chemical systems with interest in biochemistry. Independently of the size and complexity of the system, the ICD process proposed involves the emission of an electron through exchange of a virtual photon. The present theoretical study investigates the ICD process in the helium hydride anion, which involves two final product states that can be produced through a Coulomb implosion following high energy ejection of a He 1s electron accompanied by excitation to He+(n = 2) . One of the subsequent decay channels is associated with the usual emission of a single electron, to produce a stable molecule: HeH+, which can compete with the usual dissociated final state of the system. The second channel involves the emission of two electrons, leading to the usual Coulomb explosion of the final product ions He+(1 s) + H + . In addition, the process of formation of the helium hydride anion is analyzed in terms of the existing technology of ionic molecular beams and buffer gas cooling techniques. This work is supported by the National Science Foundation under Grant PHY-1306905.
Regularized friction and continuation: Comparison with Coulomb's law
Vigué, Pierre; Vergez, Christophe; Karkar, Sami; Cochelin, Bruno
2017-02-01
Periodic solutions of systems with friction are difficult to investigate because of the non-smooth nature of friction laws. This paper examines periodic solutions and most notably stick-slip, on a simple one-degree-of-freedom system (mass, spring, damper, and belt), with Coulomb's friction law, and with a regularized friction law (i.e. the friction coefficient becomes a function of relative speed, with a stiffness parameter). With Coulomb's law, the stick-slip solution is constructed step by step, which gives a usable existence condition. With the regularized law, the Asymptotic Numerical Method and the Harmonic Balance Method provide bifurcation diagrams with respect to the belt speed or normal force, and for several values of the regularization parameter. Formulations from the Coulomb case give the means of a comparison between regularized solutions and a standard reference. With an appropriate definition, regularized stick-slip motion exists, its amplitude increases with respect to the belt speed and its pulsation decreases with respect to the normal force.
Coulomb Collision for Plasma Simulations: Modelling and Numerical Methods
Geiser, Juergen
2016-09-01
We are motivated to model weakly ionized Plasma applications. The modeling problem is based on an incorporated explicit velocity-dependent small-angle Coulomb collision terms into a Fokker-Planck equation. Such a collision is done with so called test and field particles, which are scattered stochastically based on a Langevin equation. Based on such different model approaches, means the transport part is done with kinetic equations, while the collision part is done via the Langevin equations, we present a splitting of these models. Such a splitting allow us to combine different modeling parts. For the transport part, we can apply particle models and solve them with particle methods, e.g., PIC, while for the collision part, we can apply the explicit Coulomb collision model, e.g., with fast stochastic differential equation solvers. Additional, we also apply multiscale approaches for the different parts of the transport part, e.g., different time-scales of an explicit electric field, and model-order reduction approaches. We present first numerical results for particle simulations with the deterministic-stochastic splitting schemes. Such ideas can be applied to sputtering problems or plasma applications with dominant Coulomb collisions.
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...
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. Copyright © 2011 Elsevier Ltd. All rights reserved.
Propagating Uncertainties from Source Model Estimations to Coulomb Stress Changes
Baumann, C.; Jonsson, S.; Woessner, J.
2009-12-01
Multiple studies have shown that static stress changes due to permanent fault displacement trigger earthquakes on the causative and on nearby faults. Calculations of static stress changes in previous studies have been based on fault parameters without considering any source model uncertainties or with crude assumptions about fault model errors based on available different source models. In this study, we investigate the influence of fault model parameter uncertainties on Coulomb Failure Stress change (ΔCFS) calculations by propagating the uncertainties from the fault estimation process to the Coulomb Failure stress changes. We use 2500 sets of correlated model parameters determined for the June 2000 Mw = 5.8 Kleifarvatn earthquake, southwest Iceland, which were estimated by using a repeated optimization procedure and multiple data sets that had been modified by synthetic noise. The model parameters show that the event was predominantly a right-lateral strike-slip earthquake on a north-south striking fault. The variability of the sets of models represents the posterior probability density distribution for the Kleifarvatn source model. First we investigate the influence of individual source model parameters on the ΔCFS calculations. We show through a correlation analysis that for this event, changes in dip, east location, strike, width and in part north location have stronger impact on the Coulomb failure stress changes than changes in fault length, depth, dip-slip and strike-slip. Second we find that the accuracy of Coulomb failure stress changes appears to increase with increasing distance from the fault. The absolute value of the standard deviation decays rapidly with distance within about 5-6 km around the fault from about 3-3.5 MPa down to a few Pa, implying that the influence of parameter changes decrease with increasing distance. This is underlined by the coefficient of variation CV, defined as the ratio of the standard deviation of the Coulomb stress
Energy Technology Data Exchange (ETDEWEB)
Zheng, B.; Croxall, A. F.; Waldie, J., E-mail: jw353@cam.ac.uk; Sfigakis, F.; Farrer, I.; Beere, H. E.; Ritchie, D. A. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Das Gupta, K. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India)
2016-02-08
We present measurements of Coulomb drag in an ambipolar GaAs/AlGaAs double quantum well structure that can be configured as both an electron-hole bilayer and a hole-hole bilayer, with an insulating barrier of only 10 nm between the two quantum wells. Coulomb drag resistivity is a direct measure of the strength of interlayer particle-particle interactions. We explore the strongly interacting regime of low carrier densities (2D interaction parameter r{sub s} up to 14). Our ambipolar device design allows a comparison between the effects of the attractive electron-hole and repulsive hole-hole interactions and also shows the effects of the different effective masses of electrons and holes in GaAs.
Fusion around the barrier for 7Li + 12C
Indian Academy of Sciences (India)
A Mukherjee; M Dasgupta; D J Hinde; C R Morton; A C Berriman; R D Butt; J O Newton; H Timmers
2001-07-01
Fusion cross-sections for the 7Li + 12C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the -particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of 7Li may not be signiﬁcant for 7Li + 12C reaction at energies around the barrier.
2015-01-01
The coagulation of dust particles under the conditions in protoplanetary disks is investigated. The study focuses on the repulsive electrostatic barrier against growth of charged dust grains. Taking into account the photoelectric effect leads to the appearance of a layer at intermediate heights where the dust has a close to zero charge, enabling the dust grains to grow efficiently. An increase in the coagulation rate comes about not only due to the lowering of the Coulomb barrier, but also be...
Dynamical Effects on Sub-barrier Fusion of 40,48Ca+90,96Zr
Institute of Scientific and Technical Information of China (English)
ZHANG Huan-Qiao; WANG Ning; LIU Zu-Huan; YANG Feng; LIN Cheng-Jian; RUAN Ming; WU Yue-Wei; LI Zhu-Xia; WU Xi-Zhen; ZHAO Kai
2005-01-01
@@ We have measured the fusion cross sections for 48Ca+90,96Zr around the Coulomb barrier and presented them along with the experimental data of 40Ca+90,96Zr. The experimental results are compared with the improved quantum molecular dynamics model calculations. It is shown in comparison that the dynamical effects play an important role in the sub-barrier fusion reactions.
On the Analysis of Intermediate-Energy Coulomb Excitation Experiments
Scheit, Heiko; Glasmacher, Thomas; Motobayashi, Tohru
2008-01-01
In a recent publication (Bertulani et al., PLB 650 (2007) 233 and arXiv:0704.0060v2) 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 are due to the use of the wrong experimental parameters. We furthermore show that an approximate expression derived by Bertulani et al. is in fact equivalent to the theory of Winther and Alder (NPA 319 (1979) 518), an analysis method often used in the literature.
Hydrogenoid orbitals revisited: From Slater orbitals to Coulomb Sturmians
Indian Academy of Sciences (India)
Danilo Calderini; Simonetta Cavalli; Cecilia Coletti; Gaia Grossi; Vincenzo Qquilanti
2012-01-01
The simple connection between the Slater orbitals, venerable in quantum chemistry, and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics. Research in Slater orbitals mainly concerns multicentre, many-body integrals, whereas that on Sturmians exploits their orthonormality and completeness with no need of continuum states. An account of recent progress is outlined, also with reference to relationships between the two basis sets, and with the momentum space and hyperspherical harmonics representations.
Triaxiality near the 110Ru ground state from Coulomb excitation
Doherty, D. T.; Allmond, J. M.; Janssens, R. V. F.; Korten, W.; Zhu, S.; Zielińska, M.; Radford, D. C.; Ayangeakaa, A. D.; Bucher, B.; Batchelder, J. C.; Beausang, C. W.; Campbell, C.; Carpenter, M. P.; Cline, D.; Crawford, H. L.; David, H. M.; Delaroche, J. P.; Dickerson, C.; Fallon, P.; Galindo-Uribarri, A.; Kondev, F. G.; Harker, J. L.; Hayes, A. B.; Hendricks, M.; Humby, P.; Girod, M.; Gross, C. J.; Klintefjord, M.; Kolos, K.; Lane, G. J.; Lauritsen, T.; Libert, J.; Macchiavelli, A. O.; Napiorkowski, P. J.; Padilla-Rodal, E.; Pardo, R. C.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Srebrny, J.; Varner, R.; Vondrasek, R.; Wiens, A.; Wilson, E.; Wood, J. L.; Wu, C. Y.
2017-03-01
A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.
Analytical approach to quasiperiodic beam Coulomb field modeling
Rubtsova, I. D.
2016-09-01
The paper is devoted to modeling of space charge field of quasiperiodic axial- symmetric beam. Particle beam is simulated by charged disks. Two analytical Coulomb field expressions are presented, namely, Fourier-Bessel series and trigonometric polynomial. Both expressions permit the integral representation. It provides the possibility of integro-differential beam dynamics description. Consequently, when beam dynamics optimization problem is considered, it is possible to derive the analytical formula for quality functional gradient and to apply directed optimization methods. In addition, the paper presents the method of testing of space charge simulation code.
Hadronic correction to Coulomb potential between quarks and diquark structure
Energy Technology Data Exchange (ETDEWEB)
Xin-Heng, Guo [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Xue-Qian, Li; Peng-Nian, Shen [Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics; Chuang, Wang [Nankai Univ., TJ (China). Dept. of Physics
1997-07-01
We have studied the hadronic correction from the background pion fields due to the chiral symmetry breaking to the Coulomb potential that governs the short-distance behavior of the interactions between the bound quarks. The background fields are associated with the constituent quark mass. We find a modified form which favors the diquark structure. We also roughly estimate an influence of this correction on the phase shifts in nucleon scattering and find that it may cause an extra middle range attraction between nucleons which is expected. (author) 17 refs., 4 figs.
Coulomb interaction and first-order superconductor-insulator transition.
Syzranov, S V; Aleiner, I L; Altshuler, B L; Efetov, K B
2010-09-24
The superconductor-insulator transition (SIT) in regular arrays of Josephson junctions is studied at low temperatures. We derived an imaginary time Ginzburg-Landau-type action properly describing the Coulomb interaction. The renormalization group analysis at zero temperature T=0 in the space dimensionality d=3 shows that the SIT is always of the first order. At finite T, a tricritical point separates the lines of the first- and second-order phase transitions. The same conclusion holds for d=2 if the mutual capacitance is larger than the distance between junctions.
Quantum confinement and Coulomb blockade in isolated nanodiamond crystallites
Bolker, Asaf; Saguy, Cecile; Tordjman, Moshe; Kalish, Rafi
2013-07-01
We present direct experimental evidence of quantum confinement effects in single isolated nanodiamonds by scanning tunneling spectroscopy. For grains smaller than 4.5 nm, the band gap was found to increase with decreasing nanodiamond size and a well-defined, evenly spaced, 12-peak structure was observed on the conduction band side of the conductance curves. We attribute these peaks to the Coulomb blockade effect, reflecting the 12-fold degeneracy of the first electron-energy level in the confined nanodiamond. The present results shed light on the size dependence of the electronic properties of single nanodiamonds and are of major importance for future nanodiamond-based applications.
Optically induced structural phase transitions in ion Coulomb crystals
DEFF Research Database (Denmark)
Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael
2012-01-01
, such as body-centered cubic and face-centered cubic, can be suppressed by a proper choice of the potential depth and periodicity. Furthermore, by varying the harmonic trap parameters and/or the optical potential in time, controlled transitions between crystal structures can be obtained with close to unit......We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures...
Relation between the Fukui function and the Coulomb hole
Indian Academy of Sciences (India)
P Senet; M Yang
2005-09-01
By using a coarse-grain representation of the molecular electronic density, we demonstrate that the value of the condensed Fukui function at an atomic site is directly related to the polarization charge (Coulomb hole) induced by a test electron removed (or added) from (at) the atom. The link between the formation of an electron-hole pair and the condensed Fukui function provides insights on the possible negativity of the Fukui function which is interpreted in terms of two phenomena: overscreening and overstrengthening.
Mean Field Evolution of Fermions with Coulomb Interaction
Porta, Marcello; Rademacher, Simone; Saffirio, Chiara; Schlein, Benjamin
2017-03-01
We study the many body Schrödinger evolution of weakly coupled fermions interacting through a Coulomb potential. We are interested in a joint mean field and semiclassical scaling, that emerges naturally for initially confined particles. For initial data describing approximate Slater determinants, we prove convergence of the many-body evolution towards Hartree-Fock dynamics. Our result holds under a condition on the solution of the Hartree-Fock equation, that we can only show in a very special situation (translation invariant data, whose Hartree-Fock evolution is trivial), but that we expect to hold more generally.
Is the Coulomb sum rule violated in nuclei?
Morgenstern, J
2001-01-01
Guided by the experimental confirmation of the validity of the Effective Momentum Approximation (EMA) in quasi-elastic scattering off nuclei, we have re-examined the extraction of the longitudinal and transverse response functions in medium-weight and heavy nuclei. In the EMA we have performed a Rosenbluth separation of the available world data on $^{40}$Ca, $^{48}$Ca, $^{56}$Fe, $^{197}$Au, $^{208}$Pb and $^{238}$U. We find that the longitudinal response function for these nuclei is "quenched" and that the Coulomb sum is not saturated, at odds with claims in the literature.
"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications
Marshall, J. R.
1999-09-01
The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this
Intermediate-energy Coulomb excitation of Na30
Ettenauer, S.; Zwahlen, H.; Adrich, P.; Bazin, D.; Campbell, C. M.; Cook, J. M.; Davies, A. D.; Dinca, D.-C.; Gade, A.; Glasmacher, T.; Lecouey, J.-L.; Mueller, W. F.; Otsuka, T.; Reynolds, R. R.; Riley, L. A.; Terry, J. R.; Utsuno, Y.; Yoneda, K.
2008-07-01
The neutron-rich nucleus Na30 in the vicinity of the “Island of Inversion” was investigated using intermediate-energy Coulomb excitation. A single γ-ray transition was observed and attributed to the 31+→2gs+ decay. A transition probability of B(E2;2gs+→31+)=147(21)e2fm4 was determined and found in agreement with a previous experiment and with large-scale shell-model calculations. Evidence for the strong excitation of the 41+ state predicted by the shell-model calculations was not observed.
"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications
Marshall, J. R.
1999-01-01
The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this
Photon deflection by a Coulomb field in noncommutative QED
Energy Technology Data Exchange (ETDEWEB)
Pires, C A de S [Departamento de FIsica, Universidade Federal da ParaIba, Caixa Postal 5008, 58059-970, Joao Pessoa, PB (Brazil)
2004-12-01
In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be undoubted evidence of noncommutative space-time. In this work we derive a general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field. (brief report)
Photon deflection by a Coulomb field in noncommutative QED
De Pires, C A S
2004-01-01
In noncommutative QED photons present self-interactions in the form of triple and quartic interactions. The triple interaction implies that, even though the photon is electrically neutral, it will deflect when in the presence of an electromagnetic field. If detected, such deflection would be an undoubted signal of noncommutative space-time. In this work we derive the general expression for the deflection of a photon by any electromagnetic field. As an application we consider the case of the deflection of a photon by an external static Coulomb field.
Nonlocal and nonlinear electrostatics of a dipolar Coulomb fluid.
Sahin, Buyukdagli; Ralf, Blossey
2014-07-16
We study a model Coulomb fluid consisting of dipolar solvent molecules of finite extent which generalizes the point-like dipolar Poisson-Boltzmann model (DPB) previously introduced by Coalson and Duncan (1996 J. Phys. Chem. 100 2612) and Abrashkin et al (2007 Phys. Rev. Lett. 99 077801). 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 relevance of nonlocal versus nonlinear effects in continuum models of material electrostatics.
The distinguishable cluster approach from a screened Coulomb formalism.
Kats, Daniel
2016-01-28
The distinguishable cluster doubles equations have been derived starting from an effective screened Coulomb formalism and a particle-hole symmetric formulation of the Fock matrix. A perturbative triples correction to the distinguishable cluster with singles and doubles (DCSD) has been introduced employing the screened integrals. It is shown that the resulting DCSD(T) method is more accurate than DCSD for reaction energies and is less sensitive to the static correlation than coupled cluster with singles and doubles with a perturbative triples correction.
Coulomb Interaction in Quantum Dot with a Precessing Magnetic Field
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We study electronic transport through a quantum dot (QD) with a precessing magnetic field. By using the Keldysh nonequilibrium Green function method, formulas of local density of states (LDOS) and conductance of QD are derived self-consistently. It shows that the LDOS and conductance have obvious changes with the Coulomb blockade interaction. The intensity and angle of the magnetic field or temperatures, which reflect the mesoscopic structure of the QD are derived. The superiority of this device is that the QD can be controlled easily by the magnetic field, so it is valuable to apply in generating, manipulating and probing spin state.
Proton radiography, nuclear cross sections and multiple Coulomb scattering
Energy Technology Data Exchange (ETDEWEB)
Sjue, Sky K. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-11-04
The principles behind proton radiography including multiple Coulomb scattering are discussed for a purely imaginary square well nucleus in the eikonal approximation. It is found that a very crude model can reproduce the angular dependence of the cross sections measured at 24 GeV/c. The largest differences are ~3% for the 4.56 mrad data, and ~4% for the 6.68 mrad data. The prospect of understanding how to model deterministically high-energy proton radiography over a very large range of energies is promising, but it should be tested more thoroughly.
Improving Student Understanding of Coulomb's Law and Gauss's Law
Singh, Chandralekha
2016-01-01
We discuss the development and evaluation of five research-based tutorials on Coulomb's law, superposition, symmetry and Gauss's Law to help students in the calculus-based introductory physics courses learn these concepts. We discuss the performance of students on the pre-/post-tests given before and after the tutorials in three calculus-based introductory physics courses. We also discuss the performance of students who used the tutorials and those who did not use it on a multiple-choice test which employs concepts covered in the tutorials.
Momentum-space treatment of Coulomb distortions in a multiple-scattering expansion
Energy Technology Data Exchange (ETDEWEB)
Chinn, C.R. (Physics Department, Lawrence Livermore National Laboratory, Livermore, California (USA)); Elster, C. (Department of Physics, Ohio State University, Columbus, Ohio (USA)); Thaler, R.M. (Los Alamos National Laboratory, Los Alamos, New Mexico (USA) Department of Physics, Case Western Reserve University, Cleveland, Ohio (USA))
1991-10-01
The momentum-space treatment of the Coulomb interaction within the framework of the Watson multiple-scattering expansion is derived and tested numerically. By neglecting virtual Coulomb excitations and higher-order terms, the lowest-order optical potential for proton-nucleus scattering is shown to be the sum of the convolutions of a two-body nucleon-nucleon {ital t} matrix with the nuclear density and the point Coulomb interaction with the nuclear charge density. The calculation of the optical potential, as well as the treatment of the Coulomb interaction, is performed entirely in momentum space in an exact and numerically stable procedure. Elastic-scattering observables are presented for {sup 16}O, {sup 40}Ca, and {sup 208}Pb at energies up to 500 MeV. Comparisons are made with approximate treatments of the Coulomb interaction. The interference of nonlocality effects in the nuclear optical potential with different treatments of the Coulomb interaction is investigated.
Momentum-space treatment of Coulomb distortions in a multiple-scattering expansion
Chinn, C. R.; Elster, Ch.; Thaler, R. M.
1991-10-01
The momentum-space treatment of the Coulomb interaction within the framework of the Watson multiple-scattering expansion is derived and tested numerically. By neglecting virtual Coulomb excitations and higher-order terms, the lowest-order optical potential for proton-nucleus scattering is shown to be the sum of the convolutions of a two-body nucleon-nucleon t matrix with the nuclear density and the point Coulomb interaction with the nuclear charge density. The calculation of the optical potential, as well as the treatment of the Coulomb interaction, is performed entirely in momentum space in an exact and numerically stable procedure. Elastic-scattering observables are presented for 16O, 40Ca, and 208Pb at energies up to 500 MeV. Comparisons are made with approximate treatments of the Coulomb interaction. The interference of nonlocality effects in the nuclear optical potential with different treatments of the Coulomb interaction is investigated.
Lehmann, Hauke; Willing, Svenja; Möller, Sandra; Volkmann, Mirjam; Klinke, Christian
2016-07-01
Metallic nanoparticles offer possibilities to build basic electric devices with new functionality and improved performance. Due to the small volume and the resulting low self-capacitance, each single nanoparticle exhibits a high charging energy. Thus, a Coulomb-energy gap emerges during transport experiments that can be shifted by electric fields, allowing for charge transport whenever energy levels of neighboring particles match. Hence, the state of the device changes sequentially between conducting and non-conducting instead of just one transition from conducting to pinch-off as in semiconductors. To exploit this behavior for field-effect transistors, it is necessary to use uniform nanoparticles in ordered arrays separated by well-defined tunnel barriers. In this work, CoPt nanoparticles with a narrow size distribution are synthesized by colloidal chemistry. These particles are deposited via the scalable Langmuir-Blodgett technique as ordered, homogeneous monolayers onto Si/SiO2 substrates with pre-patterned gold electrodes. The resulting nanoparticle arrays are limited to stripes of adjustable lengths and widths. In such a defined channel with a limited number of conduction paths the current can be controlled precisely by a gate voltage. Clearly pronounced Coulomb oscillations are observed up to temperatures of 150 K. Using such systems as field-effect transistors yields unprecedented oscillating current modulations with on/off-ratios of around 70%.
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.
Kuraev, E A; Torosyan, H T
2013-01-01
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 corrections to the spectral bremsstrahlung rate allow completely to eliminate the discrepancy between the predictions of the LPM effect theory and its measuremens and also additionally improve the agreement between predictions of the LPM effect theory analogue for a thin target and experimental data.
Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation
Energy Technology Data Exchange (ETDEWEB)
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)
Kodera, Ryosuke
2016-01-01
We study quantized Coulomb branches of quiver gauge theories of Jordan type. We prove that the quantized Coulomb branch is isomorphic to the spherical graded Cherednik algebra in the unframed case, and is isomorphic to the spherical cyclotomic rational Cherednik algebra in the framed case. We also prove that the quantized Coulomb branch is a deformation of a subquotient of the Yangian of the affine $\\mathfrak{gl}(1)$.
Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation
Energy Technology Data Exchange (ETDEWEB)
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)
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P.; Krishnan, Sreejith; Priyanka, B. [Kannur University, School of Pure and Applied Physics, Kerala (India)
2014-04-15
The cold ternary fission of {sup 242}Cm with {sup 4}He, {sup 10}Be and {sup 14}C as light charged particle has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. The maximum yield in the {sup 4}He accompanied ternary fission is obtained for the fragmentation channel {sup 104}Mo + {sup 134}Te + {sup 4}He and for the {sup 10}Be accompanied ternary fission, the maximum yield is found for the fragmentation channel {sup 98}Zr + {sup 134}Te + {sup 10}Be. It is to be noted that, in the case of {sup 14}C accompanied ternary fission, the maximum yield is obtained for the fragmentation channel {sup 94}Sr + {sup 134}Te + {sup 14}C and the next higher yield is found for the fragmentation channel {sup 96}Zr + {sup 132}Sn + {sup 14}C. Thus, the fragment combinations with maximum yields reveal the role of doubly magic and near doubly magic nuclei in cold ternary fission. (orig.)
Przybytek, Michal; Helgaker, Trygve
2013-08-07
We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (γ(H) = 2) and eight (γ(1st) = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (αmin (G)=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d(4) with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step-namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems
Super-Coulombic atom-atom interactions in hyperbolic media
Cortes, Cristian L
2016-01-01
Dipole-dipole interactions which govern phenomena like cooperative Lamb shifts, superradiant decay rates, Van der Waals forces, as well as resonance energy transfer rates are conventionally limited to the Coulombic near-field. Here, we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic (QED) interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole-dipole coupling, referred to as a Super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom-atom interactions in hyperbolic media and propose practical implementations with phonon-polaritonic hexagonal boron nitride in the infrared spectral range and plasmonic super-lattice structures in the visible range. Our work paves the way for the control of cold atoms in hyperbolic media and the study of many-body atomic states where optical phonons mediate qua...
Super-Coulombic atom–atom interactions in hyperbolic media
Cortes, Cristian L.; Jacob, Zubin
2017-01-01
Dipole–dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole–dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom–atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon–polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media. PMID:28120826
Revision of the Coulomb logarithm in the ideal plasma
Mulser, P; Murakami, M
2013-01-01
The standard picture of the Coulomb logarithm in the ideal plasma is controversial, the arguments for the lower cut off need revision. The two cases of far subthermal and of far superthermal electron drift motions are accessible to a rigorous analytical treatment. We show that the lower cut off $b_{\\min}$ is a function of symmetry and shape of the shielding cloud, it is not universal. In the subthermal case shielding is spherical and $b_{\\min}$ is to be identified with the de Broglie wavelength; at superthermal drift the shielding cloud exhibits cylindrical (axial) symmetry and $b_{\\min}$ is the classical parameter of perpendicular deflection. In both situations the cut offs are determined by the electron-ion encounters at large collision parameters. This is in net contrast to the governing standard meaning that attributes $b_{\\min}$ to the Coulomb singularity at vanishing collision parameters $b$ and, consequently, assigns it universal validity. The origin of the contradictions in the traditional picture is ...
Absence of exponential clustering in quantum Coulomb fluids
Alastuey, A.; Martin, Ph. A.
1989-12-01
We show that the quantum corrections to the classical correlations of a Coulomb fluid do not decay exponentially fast for all values of the thermodynamical parameters. Specifically, the ħ4 term in the Wigner-Kirkwood expansion of the equilibrium charge-charge correlations of the quantum one-component plasma is found to decay like ||r||-10. More generally, using functional integration, we present a diagrammatic representation of the ħ expansion of the correlations in a multicomponent fluid with a locally regularized Coulomb potential and Maxwell-Boltzmann statistics. The ħ2n terms are found to decay algebraically for all n>=2. Furthermore, an analysis of the hierarchy equations for the correlations provides upper bounds that are compatible with the findings of the perturbative expansion. Except for the monopole, all higher-order multipole sum rules do not hold, in general, in the quantum system. This violation of the multipole sum rules as well as the related algebraic tails are due to the intrinsic quantum fluctuations that prevent a perfect organization of the screening clouds. This phenomenon is illustrated in a simpler model where the large-distance correlations between two quantum particles embedded in a classical plasma can be exactly computed.
Coulomb dissociation reactions on molybdenum isotopes for astrophysics applications
Energy Technology Data Exchange (ETDEWEB)
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.)
Room temperature Coulomb blockade mediated field emission via self-assembled gold nanoparticles
Wang, Fei; Fang, Jingyue; Chang, Shengli; Qin, Shiqiao; Zhang, Xueao; Xu, Hui
2017-02-01
Coulomb blockade mediated field-emission current was observed in single-electron tunneling devices based on self-assembled gold nanoparticles at 300 K. According to Raichev's theoretical model, by fixing a proper geometric distribution of source, island and drain, the transfer characteristics can be well explained through a combination of Coulomb blockade and field emission. Coulomb blockade and field emission alternately happen in our self-assembled devices. The Coulomb island size derived from the experimental data is in good agreement with the average size of the gold nanoparticles used in the device. The integrated tunneling can be adjusted via a gate electrode.
Controllability of the Coulomb charging energy in close-packed nanoparticle arrays.
Duan, Chao; Wang, Ying; Sun, Jinling; Guan, Changrong; Grunder, Sergio; Mayor, Marcel; Peng, Lianmao; Liao, Jianhui
2013-11-07
We studied the electronic transport properties of metal nanoparticle arrays, particularly focused on the Coulomb charging energy. By comparison, we confirmed that it is more reasonable to estimate the Coulomb charging energy using the activation energy from the temperature-dependent zero-voltage conductance. Based on this, we systematically and comprehensively investigated the parameters that could be used to tune the Coulomb charging energy in nanoparticle arrays. We found that four parameters, including the particle core size, the inter-particle distance, the nearest neighboring number, and the dielectric constant of ligand molecules, could significantly tune the Coulomb charging energy.
Sub-barrier capture with quantum diffusion approach
Directory of Open Access Journals (Sweden)
Scheid W.
2011-10-01
Full Text Available With the quantum diffusion approach the behavior of capture cross sections and mean-square angular momenta of captured systems are revealed in the reactions with deformed and spherical nuclei at sub-barrier energies. With decreasing bombarding energy under the barrier the external turning point of the nucleus-nucleus potential leaves the region of short-range nuclear interaction and action of friction. Because of this change of the regime of interaction, an unexpected enhancement of the capture cross section is found at bombarding energies far below the Coulomb barrier. This effect is shown its worth in the dependence of mean-square angular momentum on the bombarding energy. From the comparison of calculated capture cross sections and experimental capture or fusion cross sections the importance of quasiﬁssion near the entrance channel is demonstrated for the actinidebased reactions and reactions with medium-heavy nuclei at extreme sub-barrier energies.
Lehmann, Hauke; Möller, Sandra; Volkmann, Mirjam; Klinke, Christian
2016-01-01
Metallic nanoparticles offer possibilities to build basic electric devices with new functionality and improved performance. Due to the small volume and the resulting low self-capacitance, each single nanoparticle exhibits a high charging energy. Thus, a Coulomb-energy gap emerges during transport experiments that can be shifted by electric fields, allowing for charge transport whenever energy levels of neighboring particles match. Hence, the state of the device changes sequentially between conducting and non-conducting instead of just one transition from conducting to pinch-off as in semiconductors. To exploit this behavior for field-effect transistors, it is necessary to use uniform nanoparticles in ordered arrays separated by well-defined tunnel barriers. In this work, CoPt nanoparticles with a narrow size distribution are synthesized by colloidal chemistry. These particles are deposited via the scalable Langmuir-Blodgett technique as ordered, homogeneous monolayers onto Si/SiO2 substrates with pre-patterne...
Comparative studies for different proximity potentials applied to sub-barrier fusion reactions
Energy Technology Data Exchange (ETDEWEB)
Zhang, G.L. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Beihang University, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beijing (China); Qu, W.W. [Medical College of Soochow University, School of Radiation Medicine and Protection, Soochow (China); Guo, M.F.; Qian, J.Q. [Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Zhang, H.Q. [China Institute of Atomic Energy, Beijing (China); Wolski, R. [Henryk Niewodniczanski Institute of Nuclear Physics PAS, Cracow (Poland)
2016-02-15
Coulomb barrier heights calculated by using 14 different versions of proximity potentials are studied and applied for experimental data of fusion in terms of a recently proposed energy scaling approach. The results show that the descriptions of proximity potentials 77 and 88 for the barrier heights seem to be closest to the values required by the systematics. On the basis of proximity potential 77, the parameterized formulas of the barrier height and radius are obtained. These formulas can calculate the barrier positions and barrier heights reasonably well within the error, respectively. Thus it provides a simple and direct way to calculate the barrier positions and barrier heights for heavy-ion fusion reactions. (orig.)
Configurational and energy landscape in one-dimensional Coulomb systems.
Varela, Lucas; Téllez, Gabriel; Trizac, Emmanuel
2017-02-01
We study a one-dimensional Coulomb system, where two charged colloids are neutralized by a collection of point counterions, with global neutrality. With temperature being given, two situations are addressed: Either the colloids are kept at fixed positions (canonical ensemble) or the force acting on the colloids is fixed (isobaric-isothermal ensemble). The corresponding partition functions are worked out exactly, in view of determining which arrangement of counterions is optimal. How many counterions should be in the confined segment between the colloids? For the remaining ions outside, is there a left-right symmetry breakdown? We evidence a cascade of transitions as system size is varied in the canonical treatment or as pressure is increased in the isobaric formulation.
Topological defect motifs in two-dimensional Coulomb clusters
Radzvilavičius, A; 10.1088/0953-8984/23/38/385301
2012-01-01
The most energetically favourable arrangement of low-density electrons in an infinite two-dimensional plane is the ordered triangular Wigner lattice. However, in most instances of contemporary interest one deals instead with finite clusters of strongly interacting particles localized in potential traps, for example, in complex plasmas. In the current contribution we study distribution of topological defects in two-dimensional Coulomb clusters with parabolic lateral confinement. The minima hopping algorithm based on molecular dynamics is used to efficiently locate the ground- and low-energy metastable states, and their structure is analyzed by means of the Delaunay triangulation. The size, structure and distribution of geometry-induced lattice imperfections strongly depends on the system size and the energetic state. Besides isolated disclinations and dislocations, classification of defect motifs includes defect compounds --- grain boundaries, rosette defects, vacancies and interstitial particles. Proliferatio...
Properties of nuclear and Coulomb breakup of 8B
Ogata, K; Iseri, Y; Yahiro, M
2008-01-01
Dependence of breakup cross sections of 8B at 65 MeV/nucleon on target mass number A_T is investigated by means of the continuum-discretized coupled-channels method (CDCC) with more reliable distorting potentials than in preceding study. The scaling law of the nuclear breakup cross section as A_T^(1/3) is found to be satisfied only in the middle A_T region of 40 < A_T < 150. Interference between nuclear and Coulomb breakup amplitudes turns out to vanish at very forward angles with respect to the center-of-mass of 8B, independent of target nucleus. Truncation of the relative energy between the p and 7Be fragments slightly reduces contribution from nuclear breakup at very forward angles, while the angular region in which the first-order perturbation theory works well does not change essentially.
The Coulomb Branch Formula for Quiver Moduli Spaces
Manschot, Jan; Sen, Ashoke
2014-01-01
In recent series of works, by translating properties of multi-centered supersymmetric black holes into the language of quiver representations, we proposed a formula that expresses the Hodge numbers of the moduli space of semi-stable representations of quivers with generic superpotential in terms of a set of invariants associated to `single-centered' or `pure-Higgs' states. The distinguishing feature of these invariants is that they are independent of the choice of stability condition. Furthermore they are uniquely determined by the $\\chi_y$-genus of the moduli space. Here, we provide a self-contained summary of the Coulomb branch formula, spelling out mathematical details but leaving out proofs and physical motivations.
Conductance of a superconducting Coulomb-blockaded Majorana nanowire
Chiu, Ching-Kai; Sau, Jay D.; Das Sarma, S.
2017-08-01
In the presence of an applied magnetic field introducing Zeeman spin splitting, a superconducting (SC) proximitized one-dimensional (1D) nanowire with spin-orbit coupling can pass through a topological quantum phase transition developing zero-energy topological Majorana bound states (MBSs) on the wire ends. One of the promising experimental platforms in this context is a Coulomb-blockaded island, where by measuring the two-terminal conductance one can in principle investigate the MBS properties. Here, we theoretically study the tunneling transport of a single electron across the superconducting Coulomb-blockaded nanowire at finite temperature in order to obtain the generic conductance equation. By considering all possible scenarios where only MBSs are present at the ends of the nanowire, we compute the nanowire conductance as a function of the magnetic field, the temperature, and the gate voltage. In the simplest 1D topological SC model, the oscillations of the conductance peak spacings (OCPSs) arising from the Majorana overlap from the two wire ends manifest an increasing oscillation amplitude with increasing magnetic field (in disagreement with a recent experimental observation). We develop a generalized finite-temperature master-equation theory including not only multiple subbands in the nanowire, but also the possibility of ordinary Andreev bound states in the nontopological regime. Inclusion of all four effects (temperature, multiple subbands, Andreev bound states, and MBSs) provides a complete picture of the tunneling transport properties of the Coulomb-blockaded nanowire. Based on this complete theory, we indeed obtain OCPSs whose amplitudes decrease with increasing magnetic field in qualitative agreement with recent experimental results, but this happens only for rather high temperatures with multisubband occupancy and the simultaneous presence of both Andreev bound states and MBSs in the system. Thus, the experimentally observed OCPSs manifesting
Interatomic Coulombic decay widths of helium trimer: Ab initio calculations
Energy Technology Data Exchange (ETDEWEB)
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.
Plunger lifetime measurements after Coulomb excitation at intermediate beam energies
Energy Technology Data Exchange (ETDEWEB)
Hackstein, Matthias; Dewald, Alfred; Fransen, Christoph; Ilie, Gabriela; Jolie, Jan; Melon, Barbara; Pissulla, Thomas; Rother, Wolfram; Zell, Karl-Oskar [University of Cologne (Germany); Petkov, Pavel [University of Cologne (Germany); INRNE (Bulgaria); Chester, Aaron; Adrich, Przemyslaw; Bazin, Daniel; Bowen, Matt; Gade, Alexandra; Glasmacher, Thomas; Miller, Dave; Moeller, Victoria; Starosta, Krzysztof; Stolz, Andreas; Vaman, Constantin; Voss, Philip; Weissharr, Dirk [Michigan State Univerity (United States); Moeller, Oliver [TU Darmstadt (Germany)
2008-07-01
Two recoil-distance-doppler-shift (RDDS) experiments were performed at the NSCL/MSU using Coulomb excitations of the projectile nuclei {sup 110}Pd, {sup 114}Pd at beam energies of 54 MeV/u in order to investigate the evolution of deformation of neutron rich paladium isotopes. The experimental set-up consisted of a dedicated plunger device, developed at the University of Cologne, the SEGA Ge-array and the S800 spectrometer. Lifetimes of the 2{sub 1}{sup +}-states in {sup 110}Pd and {sup 114}Pd were derived from the analysis of the {gamma}-line-shapes as well as from the measured decay-curves. Special features of the data analysis, e.g. features originating from the very high recoil velocities, are discussed.
Localized Coulomb Descriptors for the Gaussian Approximation Potential
Barker, James; Hamaekers, Jan; Mathias, Sonja
2016-01-01
We introduce a novel class of localized atomic environment representation functions, based upon the global Coulomb matrix, which have dimensionality either quadratic or linear in the number of atoms in the local atomic environment. By combining these functions with the Gaussian approximation potential approach, we present LC-GAP, a new system for generating atomic potentials through machine learning (ML). Tests on the QM7, QM7b and GDB9 biomolecular datasets demonstrate that potentials created with LC-GAP can successfully predict atomization energies for molecules larger than those used for training to chemical accuracy, and can (in the case of QM7b) also be used to predict a range of other atomic properties with accuracy in line with the recent literature.
Imaging of Coulomb-Driven Quantum Hall Edge States
Lai, Keji
2011-10-01
The edges of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime are divided into alternating metallic and insulating strips, with their widths determined by the energy gaps of the QHE states and the electrostatic Coulomb interaction. Local probing of these submicrometer features, however, is challenging due to the buried 2DEG structures. Using a newly developed microwave impedance microscope, we demonstrate the real-space conductivity mapping of the edge and bulk states. The sizes, positions, and field dependence of the edge strips around the sample perimeter agree quantitatively with the self-consistent electrostatic picture. The evolution of microwave images as a function of magnetic fields provides rich microscopic information around the ν=2 QHE state. © 2011 American Physical Society.
Coulomb and nuclear excitations of narrow resonances in 17Ne
Directory of Open Access Journals (Sweden)
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 blockade and BLOCH oscillations in superconducting Ti nanowires.
Lehtinen, J S; Zakharov, K; Arutyunov, K Yu
2012-11-01
Quantum fluctuations in quasi-one-dimensional superconducting channels leading to spontaneous changes of the phase of the order parameter by 2π, alternatively called quantum phase slips (QPS), manifest themselves as the finite resistance well below the critical temperature of thin superconducting nanowires and the suppression of persistent currents in tiny superconducting nanorings. Here we report the experimental evidence that in a current-biased superconducting nanowire the same QPS process is responsible for the insulating state--the Coulomb blockade. When exposed to rf radiation, the internal Bloch oscillations can be synchronized with the external rf drive leading to formation of quantized current steps on the I-V characteristic. The effects originate from the fundamental quantum duality of a Josephson junction and a superconducting nanowire governed by QPS--the QPS junction.
Quasi-exactly solvable relativistic soft-core Coulomb models
Agboola, Davids
2013-01-01
By considering a unified treatment, we present quasi exact polynomial solutions to both the Klein-Gordon and Dirac equations with the family of soft-core Coulomb potentials $V_q(r)=-Z/\\left(r^q+\\beta^q\\right)^{1/q}$, $Z>0$, $\\beta>0$, $q\\geq 1$. We consider cases $q=1$ and $q=2$ and show that both cases are reducible to the same basic ordinary differential equation. A systematic and closed form solution to the basic equation is obtain using the Bethe ansatz method. For each case, the expressions for the energies and the allowed parameters are obtained analytically and the wavefunctions are derive in terms of the roots of a set of Bethe ansatz equations.
Exact Extremal Statistics in the Classical 1D Coulomb Gas
Dhar, Abhishek; Kundu, Anupam; Majumdar, Satya N.; Sabhapandit, Sanjib; Schehr, Grégory
2017-08-01
We consider a one-dimensional classical Coulomb gas of N -like charges in a harmonic potential—also known as the one-dimensional one-component plasma. We compute, analytically, the probability distribution of the position xmax of the rightmost charge in the limit of large N . We show that the typical fluctuations of xmax around its mean are described by a nontrivial scaling function, with asymmetric tails. This distribution is different from the Tracy-Widom distribution of xmax for Dyson's log gas. We also compute the large deviation functions of xmax explicitly and show that the system exhibits a third-order phase transition, as in the log gas. Our theoretical predictions are verified numerically.
Coulomb interaction effect in tilted Weyl fermion in two dimensions
Isobe, Hiroki; Nagaosa, Naoto
Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)2I3 and three-dimensional WTe2. The Coulomb interaction between electrons modifies the velocities in an essential way in the low energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the velocity of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.
Phase diagram of a bulk 1d lattice Coulomb gas
Démery, V.; Monsarrat, R.; Dean, D. S.; Podgornik, R.
2016-01-01
The exact solution, via transfer matrix, of the simple one-dimensional lattice Coulomb gas (1d LCG) model can reproduce peculiar features of ionic liquid capacitors, such as overscreening, layering, and camel- and bell-shaped capacitance curves. Using the same transfer matrix method, we now compute the bulk properties of the 1d LCG in the constant voltage ensemble. We unveil a phase diagram with rich structure exhibiting low-density disordered and high-density ordered phases, separated by a first-order phase transition at low temperature; the solid state at full packing can be ordered or not, depending on the temperature. This phase diagram, which is strikingly similar to its three-dimensional counterpart, also sheds light on the behaviour of the confined system.
Investigation of uncertainty components in Coulomb blockade thermometry
Energy Technology Data Exchange (ETDEWEB)
Hahtela, O. M.; Heinonen, M.; Manninen, A. [MIKES Centre for Metrology and Accreditation, Tekniikantie 1, 02150 Espoo (Finland); Meschke, M.; Savin, A.; Pekola, J. P. [Low Temperature Laboratory, Aalto University, Tietotie 3, 02150 Espoo (Finland); Gunnarsson, D.; Prunnila, M. [VTT Technical Research Centre of Finland, Tietotie 3, 02150 Espoo (Finland); Penttilä, J. S.; Roschier, L. [Aivon Oy, Tietotie 3, 02150 Espoo (Finland)
2013-09-11
Coulomb blockade thermometry (CBT) has proven to be a feasible method for primary thermometry in every day laboratory use at cryogenic temperatures from ca. 10 mK to a few tens of kelvins. The operation of CBT is based on single electron charging effects in normal metal tunnel junctions. In this paper, we discuss the typical error sources and uncertainty components that limit the present absolute accuracy of the CBT measurements to the level of about 1 % in the optimum temperature range. Identifying the influence of different uncertainty sources is a good starting point for improving the measurement accuracy to the level that would allow the CBT to be more widely used in high-precision low temperature metrological applications and for realizing thermodynamic temperature in accordance to the upcoming new definition of kelvin.
Screening phase transitions in two-dimensional Coulomb gas
Energy Technology Data Exchange (ETDEWEB)
Gallavotti, G.; Nicolo, F.
1984-07-01
Infrared properties of a Coulomb gas in two dimensions and with fixed ultraviolet cutoff are studied. The existence of infinitely many thresholds Tu = 1/Ke 1/8 pi (1-1/zu)sup-1 in the interval of temperatures 1/Ke1/8 pi, 1/4 pi, where K is the Boltzmann constant and e = /e/ is the charge of the positive particle, is proved. Such thresholds are conjectured to reflect a sequence of transitions from a pure multipole phase (the Koesterlitz-Thouless region) to the plasma phase via an infinite number of intermediate phases. Mathematically the free energy becomes more and more differentiable as a function of the activity lambda, near lambda = 0, as the temperature decreases.
Quantum Effects on the Coulomb Logarithm for Energetic IonsDuring the Initial Thermalization Phase
Institute of Scientific and Technical Information of China (English)
邓柏权; 严建成; 邓梅根; 彭利林
2002-01-01
We have discussed the quantum mechanical effects for the energetic charged particles produced in D - He3 fusionreactions. Our results show that it is better to use the proper Coulomb logarithm at the high-energy end indescribing the thermalization process, because the quantum mechanical effects on the Coulomb logarithm are notnegligible, based on an assumption of binary collision.
Influence of gun design on Coulomb interactions in a field emission gun
Verduin, T.; Cook, B.; Kruit, P.
2011-01-01
The authors investigate by simulation the Coulomb effects on brightness and energy spread for cold field emitters. At first, we show that brightness is ultimately limited by Coulomb interactions. The authors analyze the maximum attainable brightness for tip radii ranging from 1 nm to 1 μm. Remarkabl
Study of the dynamical potential barriers in heavy ion collisions
Zhu, Long; Su, Jun; Xie, Wen-Jie; Zhang, Feng-Shou
2013-10-01
The nucleus-nucleus interaction potentials for the fusion reactions 16O + 208Pb, 64Ni + 64Ni, 58Ni + 58Ni and 16O + 154Sm are extracted from the improved isospin-dependent quantum molecular dynamics model. The shell correction effects are discussed. The negative shell correction energies lower potential barriers of a certain reaction. The incident energy dependence of the potential barrier is investigated for each system. A complex phenomenon of energy dependence is observed. It is also found that incident energy dependence of the barrier radius and barrier height shows opposite behaviors. The Coulomb potential shows weak energy dependence when distance of two colliding nuclei is lower than the touching distance. The isospin effects of the potential barrier are investigated. The orientation effects of the potential barrier is also discussed for the system 16O + 154Sm. The fusion cross sections that correspond to the equatorial orientation of 154Sm are very low in sub-barrier region because of the high fusion barriers and the shallow potential pockets.
Plane density of induced vacuum charge in a supercritical Coulomb potential
Khalilov, V R
2016-01-01
An expression for the density of a planar induced vacuum charge is obtained in a strong Coulomb potential in coordinate space. Treatment is based on a self-adjoint extension approach for constructing of the Green's function of a charged fermion in this potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. The behavior of the obtained vacuum charge density is investigated at long and short distances from the Coulomb center. The induced vacuum charge has a screening sign. Screening of a Coulomb impurity in graphene is briefly discussed. We calculate the real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in the supercritical Coulomb potential due to the so-called real vacuum polarization. It is shown that the vacuum charge densities essentially differ in massive and massless cases. We expect that our results can, as a matter of principle, be tested in graphene with a supe...
Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials
Energy Technology Data Exchange (ETDEWEB)
Roy Chowdhury, Dibakar, E-mail: dibakar.roychowdhury@anu.edu.au [Center for Sustainable Energy Systems, College of Engineering and Computer Science, Australian National University, Canberra 0200 (Australia); College of Engineering, Mahindra Ecole Centrale, Jeedimetla, Hyderabad, 500043 (India); Xu, Ningning; Zhang, Weili [School of Electrical Engineering and Computer Science, Oklahoma State University, Stillwater, Oklahoma 87074 (United States); Singh, Ranjan, E-mail: ranjans@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)
2015-07-14
Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.
Khushboo, Mandal, S.; Nath, S.; Madhavan, N.; Gehlot, J.; Jhingan, A.; Kumar, Neeraj; Banerjee, Tathagata; Kaur, Gurpreet; Rojeeta Devi, K.; Banerjee, A.; Neelam, Varughese, T.; Siwal, Davinder; Garg, R.; Mukul, Ish; Saxena, M.; Verma, S.; Kumar, S.; Behera, B. R.; Verma, P.
2017-07-01
Background: It is a well established fact that nuclear deformation and vibration influence fusion dynamics around the Coulomb barrier. This effect was observed for several systems with the inclusion of inelastic excitations in coupled-channels calculations. Sub-barrier fusion cross sections were also observed to be affected by neutron transfer in systems carrying positive Q value for transfer channels. However, recent experimental analysis with a few systems showed that inelastic excitations are enough to explain the sub-barrier fusion behavior, and no effect was noticed due to positive Q -value transfer channels. Purpose: The motivation behind present investigation is to explore the effects of colliding nuclei structure and the transfer channel on enhancement of sub-barrier fusion cross sections. Method: An experiment was performed with Heavy Ion Reaction Analyzer (HIRA) at New Delhi to measure the fusion cross sections for 28Si+Zr,9692 systems. These cross sections were later compared with quantum mechanical coupled-channels calculations. In order to explore the effects of nuclear deformation on fusion cross sections, the present data were compared with those of other researchers on fusion who have used various projectiles of different structural properties on a 96Zr target. Results: Experimental fusion cross sections have been extracted around the Coulomb barrier. In the coupled-channels framework, inclusion of inelastic excitations of both projectile (28Si) and targets (Zr,9692) could reproduce the experimental cross sections around the Coulomb barrier, but they deviated substantially in the sub-barrier region. This indicates that positive Q -value neutron transfer channels may need to be included in the calculations to reproduce the experimental cross sections at sub-barrier energies. Conclusions: The nuclear structure of interacting nuclei has a strong influence on sub-barrier fusion enhancement. The effect of multineutron transfer channels was observed to be
Strong-Field S-Matrix Theory With Coulomb-Volkov Final State in All Orders
Faisal, F H M
2016-01-01
Despite its long standing usefulness for the analysis of various processes in intense laser fields, it is well-known that the so-called strong-field KFR or SFA ansatz does not account for the final-state Coulomb interaction. Due to its importance for the ubiquitous ionisation process, numerous heuristic attempts have been made during the last several decades to account for the final state Coulomb interaction with in the SFA. Also to this end an ad hoc model with the so-called Coulomb-Volkov final state was introduced a long time ago. However, till now, no systematic strong-field S-matrix expansion using the Coulomb-Volkov final state could be found. Here we solve this long standing problem by determining the Coulomb-Volkov Hamiltonian, identifying the rest-interaction in the final state, and explicitly constructng the Coulomb-Volkov propagator (or Green's function). We employ them to derive the complete S-matrix series for the ionisation amplitude governed by the Coulomb-Volkov final state in all orders. The ...
Energy Technology Data Exchange (ETDEWEB)
Zhang Wenwen; Hou Xun [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); Wu Zhaoxin; Liang Shixiong; Jiao Bo; Zhang Xinwen; Wang Dawei [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Key Laboratory of Photonics Technology for Information of ShaanXi Province, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen Zhijian; Gong Qihuang, E-mail: zhaoxinwu@mail.xjtu.edu.cn [State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871 (China)
2011-04-20
The luminance decays of organic light-emitting diodes (OLEDs) are investigated with initial luminance of 1000 to 20 000 cd m{sup -2} through a scalable Coulombic degradation and a stretched exponential decay. We found that the estimated lifetime by scalable Coulombic degradation deviates from the experimental results when the OLEDs work with high initial luminance. By measuring the temperature of the device during degradation, we found that the higher device temperatures will lead to instabilities of organic materials in devices, which is expected to result in the difference between the experimental results and estimation using the scalable Coulombic degradation.
Effect of Cluster Coulomb Fields on Electron Acceleration in Laser-Cluster Interaction
Institute of Scientific and Technical Information of China (English)
CANG Yu; DONG Quan-Li; WU Hui-Chun; SHENG Zheng-Ming; YU Wei; ZHANG Jie
2004-01-01
@@ Single particle simulations are used to investigate electron acceleration in the laser-clusterinteraction, taking into account the Coulomb fields around individual clusters. These Coulomb fields are induced from the cluster cores with positive charge when electrons escape from the cluster cores through ponderomotive push from the laser field. These Coulomb fields enable some stripped electrons to be stochastically in phases with the laser fields so that they can gain net energy from the laser efficiently. In this heating mechanism, circularly polarized lasers, larger cluster size and higher cluster densities make the acceleration more efficient.
Anderson localisation on the Falicov-Kimball model with Coulomb disorder
Carvalho, Rubens D. B.; Almeida, Guilherme M. A.; Souza, Andre M. C.
2014-07-01
The role of Coulomb disorder is analysed in the Anderson-Falicov-Kimball model. Phase diagrams are obtained by means of dynamical mean-field theory applied to the Bethe lattice, in which metal-insulator transitions driven by Anderson and Coulomb disorder can be identified. Metallic, Mott insulator, and Anderson insulator phases, as well as the crossover between them are studied in this framework. We show that Coulomb disorder has a relevant role in the phase-transition behaviour as the system is led towards the insulator regime.
Coulomb scatter of diamagnetic dust particles in a cusp magnetic trap under microgravity conditions
Energy Technology Data Exchange (ETDEWEB)
Myasnikov, M. I., E-mail: miasnikovmi@mail.ru; D’yachkov, L. G.; Petrov, O. F.; Vasiliev, M. M., E-mail: mixxy@mail.ru; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Savin, S. F.; Serova, E. O. [Korolev Rocket and Space Corporation Energia, ul. Lenina 4A (Russian Federation)
2017-02-15
The effect of a dc electric field on strongly nonideal Coulomb systems consisting of a large number (~10{sup 4}) of charged diamagnetic dust particles in a cusp magnetic trap are carried out aboard the Russian segment of the International Space Station (ISS) within the Coulomb Crystal experiment. Graphite particles of 100–400 μm in size are used in the experiments. Coulomb scatter of a dust cluster and the formation of threadlike chains of dust particles are observed experimentally. The processes observed are simulated by the molecular dynamics (MD) method.
Nugraha, Mohamad Insan; Darma, Yudi
2012-06-01
In this paper, we simulate the effect of interaction between electrons on the electrical characteristic of silicon based single electron transistor (SET). The interaction between electrons is defined in the term of Coulomb blockade effect. These electrical characteristics involve conductance and I-V characteristic in SET structure. The simulation results show that when Coulomb blockade effect is included, the characteristic of I-V and conductance in SET shift to right. In addition, by reducing the quantum dot size, Coulomb blockade effect contributes greater effect. These results are shown in the characteristic of I-V and conductance which shift greater to the right in smaller quantum dot.
Analytical expressions for partial wave two-body Coulomb transition matrices at ground-state energy
Kharchenko, V. F.
2016-11-01
Leaning upon the Fock method of the stereographic projection of the three-dimensional momentum space onto the four-dimensional unit sphere the possibility of the analytical solving of the Lippmann-Schwinger integral equation for the partial wave two-body Coulomb transition matrix at the ground bound state energy has been studied. In this case new expressions for the partial p-, d- and f-wave two-body Coulomb transition matrices have been obtained in the simple analytical form. The developed approach can also be extended to determine analytically the partial wave Coulomb transition matrices at the energies of excited bound states.
Large ion Coulomb crystals: A near-ideal medium for coupling optical cavity modes to matter
DEFF Research Database (Denmark)
Dantan, Aurélien; Albert, Magnus; Marler, Joan
2009-01-01
We present an investigation of the coherent coupling of various transverse field modes of an optical cavity to ion Coulomb crystals. The obtained experimental results, which include the demonstration of identical collective coupling rates for different transverse modes of a cavity field to ions...... in the same large Coulomb crystal, are in excellent agreement with theoretical predictions. The results furthermore suggest that Coulomb crystals in the future may serve as near-ideal media for high-fidelity multimode quantum information processing and communication purposes, including the generation...
Coulomb impurity effects on the zero-Landau level splitting of graphene on polar substrates
Xiao, Yao; Li, Wei-Ping; Li, Zhi-Qing; Wang, Zi-Wu
2017-04-01
We theoretically investigate the effects of the Coulomb impurity on the zero-Landau level splitting of graphene on different polar substrates basing on the Fröhlich polaron model, in which the polaron is formed due to the carriers-surface optical phonon coupling. We discuss the influence of Coulomb impurity on the zero-Landau level splitting in the case of weak and strong coupling limits. We find that the splitting energy can be varied in a large scale due to the Coulomb impurity, which provides the possible theoretical explanation for the experimental measurements regarding the energy gap opened and zero-Landau level splitting in Landau quantized graphene.
Le probleme quantique bicomplexe du potentiel de Coulomb
Mathieu, Jeremie
In this master's thesis, is gathered a great part of my work on bicomplex quantum mechanics. Bicomplex numbers are the second order multicomplex generalization of complex numbers. Equipped with the standard addition and multiplication, they form an algebraic structure called a commutative ring with unity and are one of many known generalizations of the real number system. It has been almost eighty years since it's been proposed to use an algebra of a superior dimension than the one of complex numbers to construct the mathematical formalism of quantum mechanics. However it's only been since less than a decade ago that the idea of using the bicomplex numbers to do so has been seriously considered. In that sense, the complete resolution of the quantum harmonic oscillator in a bicomplex Hilbert space was the first major achievement of this ambitious project. This thesis, by article style, is a continuation of this work of generalization. It presents, by an axiomatic approach, the complete differential solution of the bicomplex quantum Coulomb potential problem and half of its algebraic solution.
Coulomb nuclear interference with deuterons in even palladium isotopes
Energy Technology Data Exchange (ETDEWEB)
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)
A new graphene composite with a high coulombic efficiency
Protich, Z.; Wong, P.; Santhanam, K. S. V.
2016-11-01
Zinc-graphene composite has been electrolytically produced for the first time using a graphene quantum dot (GQD) electrode. The electrochemical reduction of zinc ion at a GQD electrode is shifted to a lesser negative potential with the complimentary anodic peak due to the oxidation of the composite shifted towards a positive potential as compared to zinc ion reduction in the GQD bath. The coulombic efficiency of the composite represents a gain of nearly 10% over the conventional Zn/Zn2+ in the energy storage systems. In galvanostatic electrolysis, the deposition of zinc-graphene composite is carried out under neutral and acidic conditions. The X-ray diffraction of the electrolytically prepared composite shows distinct features of 2 theta reflection at 8° due to (001) plane of graphene, in addition to the characteristic reflections at 38.9°,43.2°, 54.3°, 70.1° and 90° arising from Zn at (002), (100), (101), (102) and (110). A large scale preparation of the zinc-graphene composite has been achieved at a zinc plate as the working electrode in the GQD bath. The composite is stable up to 250 °C. Scanning electron microscopic (SEM) and energy dispersion X-ray analysis (EDAX) shows a string like structure with peaks for carbon and zinc in EDAX.
Many-Body Coulomb Gauge Exotic and Charmed Hybrids
Llanes-Estrada, F J; Llanes-Estrada, Felipe J.; Cotanch, Stephen R.
2001-01-01
Utilizing a QCD Coulomb gauge Hamiltonian with linear confinement specified by lattice, we report a relativistic many-body calculation for the light exotic and charmed hybrid mesons. The Hamiltonian successfully describes both quark and gluon sectors, with vacuum and quasiparticle properties generated by a BCS transformation and more elaborate TDA and RPA diagonalizations for the meson ($q\\bar{q}$) and glueball ($gg$) masses. Hybrids entail a computationally intense relativistic three quasiparticle ($q\\bar{q}g$) calculation with the 9 dimensional Hamiltonian matrix elements evaluated variationally by Monte Carlo techniques. Our new TDA spectrum for the nonexotic $1^{--}$ charmed ($c\\bar{c}$ and $c\\bar{c}g$) system provides an explanation for the overpopulation of the observed $J/\\psi$ states. For the important $1^{-+}$ light exotic channel we obtain hybrid masses above 2 $GeV$, in broad agreement with lattice and flux tube models, indicating that the recently observed resonances at 1.4 and 1.6 $GeV$ are of di...
Coulomb pairing resonances in multiple-ring aromatic molecules
Huber, D L
2015-01-01
We present an analysis of the Coulomb pairing resonances observed in photo-double-ionization studies of CnHm aromatic molecules with multiple benzene-like rings. It is applied to naphthalene, anthracene, phenanthrene, pyrene and coronene, all of which have six-member rings, and azulene which is comprised of a five-member and a seven-member ring. There is a high energy resonance at ~ 40 eV that is found in all of the molecules cited and is associated with paired electrons localized on carbon sites on the perimeter of the molecule, each of which having two carbon sites as nearest neighbors. The low energy resonance at 10 eV, which is found only in pyrene and coronene, is attributed to the formation of paired electrons localized on arrays of interior carbon atoms that have the point symmetry of the molecule with each carbon atom having three nearest neighbors. The origin of the anomalous increase in the doubly charged to singly charged parent-ion ratio that is found above the 40 eV resonance in all of the cited ...
Three-body quantum Coulomb problem: Analytic continuation
Turbiner, A. V.; Lopez Vieyra, J. C.; Olivares Pilón, H.
2016-08-01
The second (unphysical) critical charge in the three-body quantum Coulomb system of a nucleus of positive charge Z and mass mp, and two electrons, predicted by Stillinger has been calculated to be equal to ZB∞ = 0.904854 and ZBmp = 0.905138 for infinite and finite (proton) mass mp, respectively. It is shown that in both cases, the ground state energy E(Z) (analytically continued beyond the first critical charge Zc, for which the ionization energy vanishes, to ReZ
Dark Coulomb binding of heavy neutrinos of fourth family
Belotsky, K. M.; Esipova, E. A.; Khlopov, M. Yu.; Laletin, M. N.
2015-11-01
Direct dark matter searches put severe constraints on the weakly interacting massive particles (WIMPs). These constraints cause serious troubles for the model of stable neutrino of fourth generation with mass around 50GeV. Though the calculations of primordial abundance of these particles make them in the charge symmetric case a sparse subdominant component of the modern dark matter, their presence in the universe would exceed the current upper limits by several orders of the magnitude. However, if quarks and leptons of fourth generation possess their own Coulomb-like y-interaction, recombination of pairs of heavy neutrinos and antineutrinos and their annihilation in the “neutrinium” atoms can play important role in their cosmological evolution, reducing their modern abundance far below the experimental upper limits. The model of stable fourth generation assumes that the dominant part of dark matter is explained by excessive Ū antiquarks, forming (ŪŪŪ)-- charged clusters, bound with primordial helium in nuclear-interacting O-helium (OHe) dark atoms. The y charge conservation implies generation of the same excess of fourth generation neutrinos, potentially dangerous WIMP component of this scenario. We show that due to y-interaction recombination of fourth neutrinos with OHe hides these WIMPs from direct WIMP searches, leaving the negligible fraction of free neutrinos, what makes their existence compatible with the experimental constraints.
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...
The Thermodynamic Limit of Quantum Coulomb Systems. Part II. Applications
Hainzl, Christian; Solovej, Jan Philip
2008-01-01
In a previous paper, we have developed a general theory of thermodynamic limits. We apply it here to three different Coulomb quantum systems, for which we prove the convergence of the free energy per unit volume. The first system is the crystal for which the nuclei are classical particles arranged periodically in space and only the electrons are quantum particles. We recover and generalize a previous result of Fefferman. In the second example, both the nuclei and the electrons are quantum particles, submitted to a periodic magnetic field. We thereby extend a seminal result of Lieb and Lebowitz. Finally, in our last example we take again classical nuclei but optimize their position. To our knowledge such a system was never treated before. The verification of the assumptions introduced in the previous paper uses several tools which have been introduced before in the study of large quantum systems. In particular, an electrostatic inequality of Graf and Schenker is one main ingredient of our new approach.
Enhanced current noise correlations in a Coulomb-Majorana device
Lü, Hai-Feng; Lu, Hai-Zhou; Shen, Shun-Qing
2016-06-01
Majorana bound states (MBSs) nested in a topological nanowire are predicted to manifest nonlocal correlations in the presence of a finite energy splitting between the MBSs. However, the signal of the nonlocal correlations has not yet been detected in experiments. A possible reason is that the energy splitting is too weak and seriously affected by many system parameters. Here we investigate the charging energy induced nonlocal correlations in a hybrid device of MBSs and quantum dots. The nanowire that hosts the MBSs is assumed in proximity to a mesoscopic superconducting island with a finite charging energy. Each end of the nanowire is coupled to one lead via a quantum dot with resonant levels. With a floating superconducting island, the devices show a negative differential conductance and giant super-Poissonian shot noise, due to the interplay between the nonlocality of the MBSs and dynamical Coulomb blockade effect. When the island is strongly coupled to a bulk superconductor, the current cross correlations at small lead chemical potentials are negative by tuning the dot energy levels. In contrast, the cross correlation is always positive in a non-Majorana setup. This difference may provide a signature for the existence of the MBSs.
Coulomb drag and tunneling studies in quantum Hall bilayers
Nandi, Debaleena
The bilayer quantum Hall state at total filling factor νT=1, where the total electron density matches the degeneracy of the lowest Landau level, is a prominent example of Bose-Einstein condensation of excitons. A macroscopically ordered state is realized where an electron in one layer is tightly bound to a "hole" in the other layer. If exciton transport were the only bulk transportmechanism, a current driven in one layer would spontaneously generate a current of equal magnitude and opposite sign in the other layer. The Corbino Coulomb drag measurements presented in this thesis demonstrate precisely this phenomenon. Excitonic superfluidity has been long sought in the νT=1 state. The tunneling between the two electron gas layers exihibit a dc Josephson-like effect. A simple model of an over-damped voltage biased Josephson junction is in reasonable agreement with the observed tunneling I -- V. At small tunneling biases, it exhibits a tunneling "supercurrent". The dissipation is carefully studied in this tunneling "supercurrent" and found to remain small but finite.
Proton emission with a screened electrostatic barrier
Budaca, R.; Budaca, A. I.
2017-08-01
Half-lives of proton emission for Z≥ 51 nuclei are calculated within a simple analytical model based on the WKB approximation for the barrier penetration probability which includes the centrifugal and overlapping effects besides the electrostatic repulsion. The model has a single free parameter associated to a Hulthen potential which emulates a Coulomb electrostatic interaction only at short distance. The agreement with experimental data is very good for most of the considered nuclei. Theoretical predictions are made for few cases with uncertain emitting state configuration or incomplete decay information. The model's assignment of the proton orbital momentum is in agreement with the differentiation of the experimental data by orbital momentum values realized with a newly introduced correlation formula.
Energy Technology Data Exchange (ETDEWEB)
García-Ravelo, J., E-mail: g.ravelo@hotmail.com [Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, México D.F., 07738 (Mexico); Menéndez, A.; García-Martínez, J. [Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Edificio 9, Unidad Profesional Adolfo López Mateos, México D.F., 07738 (Mexico); Schulze-Halberg, A. [Department of Mathematics and Actuarial Science and Department of Physics, Indiana University Northwest, 3400 Broadway, Gary, IN 46408 (United States)
2014-06-13
We show that the effective Kratzer and Coulomb potentials can be obtained by taking particular limits of a multiparameter exponential potential that was studied recently. Moreover, we demonstrate that the bound state solutions of the exponential potential reduce correctly to their well-known counterparts associated with the Kratzer and Coulomb potentials. As a byproduct, we obtain a new limit relation for the hypergeometric function. - Highlights: • Kratzer and Coulomb potentials are limit cases of an exponential-type potential. • From exact s-waves, approximate solutions for l-waves are obtained. • l-waves of the potential tend to the solutions of the Kratzer and Coulomb potentials. • A non-evident identity between hypergeometric functions is demonstrated.
Deconvoluting nonaxial recoil in Coulomb explosion measurements of molecular axis alignment
Christensen, Lauge; Christiansen, Lars; Shepperson, Benjamin; Stapelfeldt, Henrik
2016-08-01
We report a quantitative study of the effect of nonaxial recoil during Coulomb explosion of laser-aligned molecules and introduce a method to remove the blurring caused by nonaxial recoil in the fragment-ion angular distributions. Simulations show that nonaxial recoil affects correlations between the emission directions of fragment ions differently from the effect caused by imperfect molecular alignment. The method, based on analysis of the correlation between the emission directions of the fragment ions from Coulomb explosion, is used to deconvolute the effect of nonaxial recoil from experimental fragment angular distributions. The deconvolution method is then applied to a number of experimental data sets to correct the degree of alignment for nonaxial recoil, to select optimal Coulomb explosion channels for probing molecular alignment, and to estimate the highest degree of alignment that can be observed from selected Coulomb explosion channels.
Generalized ladder operators for the Dirac-Coulomb problem via SUSY QM
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, R. de Lima [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Universidade Federal de Campina Grande, PB (Brazil). Centro de Formacao de Professores. Dept. de Ciencias Exatas e da Natureza; E-mail: rafaelr@cbpf.br
2003-12-15
The supersymmetry in quantum mechanics and shape invariance condition are applied as an algebraic method to solving the Dirac-Coulomb problem. The ground state and the excited states are investigated via new generalized ladder operators. (author)
Shape coexistence in neutron-rich Sr isotopes : Coulomb excitation of 98Sr
Clément, E; Görgen, A.; Korten, W.; Walle J. van de, [No Value
2010-01-01
In this addendum we ask for beam time to perform Coulomb excitation of 98Sr in order to complete our program on the study of shape coexistence and evolution of collectivity in neutron rich strontium isotopes at N=60.
Energy Technology Data Exchange (ETDEWEB)
Dragulescu, E.; Duma, M.; Ivascu, M.; Popescu, D.; Semenescu, G.; Mihu, R.
1981-01-01
This paper presents a package of computer programs, to be used as a tool for the obtaining of spectroscopic information, such as theoretical yields, reduced transition probabilities and multipole mixing ratios from experimental Coulomb excitation data. 12 references.
Partial-wave Coulomb transition matrices for attractive interaction by Fock's method
Kharchenko, V F
2016-01-01
Leaning upon the Fock method of the stereographic projection of the three-dimensional momentum space onto the four-dimensional unit sphere the possibility of the analytical solving of the Lippmann-Schwinger integral equation for the partial wave two-body Coulomb transition matrix at the ground bound state energy has been studied. In this case new expressions for the partial p-, d- and f-wave two-body Coulomb transition matrices have been obtained in the simple analytical form. The developed approach can also be extended to determine analytically the partial wave Coulomb transition matrices at the energies of excited bound states. Keywords: Partial wave Coulomb transition matrix; Lippmann-Schwinger equation; Fock method; Analytical solution PACS Nos. 03.65.-w; 03.65.Nk; 34.20.Cf
Thermodynamic Curvature and Phase Transitions from Black Hole with a Coulomb-Like Field
Institute of Scientific and Technical Information of China (English)
HAN Yi-Wen; BAO Zhi-Qing; HONG Yun
2011-01-01
In this paper, we first investigate the thermodynamic features of the black hole with a coulomb-like field.Moreover, we obtain the geometric description of the black hole thermodynamics.We find that for the black hole with a coulomb-like field the Weinhold geometry is flat, whereas its Ruppeiner geometry is curved.For the heat capacity and curvature calculation shows the Ruppeiner geometry has a transition point.
Coulomb dissociation of {sup 8}B at 254 A MeV
Energy Technology Data Exchange (ETDEWEB)
Suemmerer, K.; Boue, F.; Baumann, T.; Geissel, H.; Hellstroem, M.; Koczon, P.; Schwab, E.; Schwab, W.; Senger, P.; Surowiecz, A. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany); Iwasa, N.; Ozawa, A. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)]|[RIKEN Institute of Physical and Chemical Research, Saitama (Japan); Surowka, G. [Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)]|[Jagiellonian Univ., Krakow (Poland). Inst. of Physics; Blank, B.; Czajkowski, S.; Marchand, C.; Pravikoff, M.S. [Centre d`Etudes Nucleaires de Bordeaux-Gradignan, 33 (France); Foerster, A.; Lauer, F.; Oeschler, H.; Speer, J.; Sturm, C.; Uhlig, F.; Wagner, A. [Technische Univ. Darmstadt (Germany); Gai, M. [Connecticut Univ., Storrs, CT (United States). Dept. of Physics; Grosse, E. [Inst. fuer Kern- und Hadronenphysik, Forschungszentrum Rossendorf, Dresden (Germany); Kohlmeyer, B. [Philipps Univ., Marburg (Germany). Fachbereich Physik; Kulessa, R.; Walus, W. [Jagiellonian Univ., Krakow (Poland). Inst. of Physics; Motobayashi, T. [Rikkyo Univ., Tokyo (Japan). Dept. of Physics; Teranishi, T. [RIKEN Institute of Physical and Chemical Research, Saitama (Japan)
1998-06-01
As an alternative method for determining the astrophysical S-factor for the {sup 7}Be(p,{gamma}){sup 8}B reaction we have measured the Coulomb dissociation of {sup 8}B at 254 A MeV. From our preliminary results, we obtain good agreement with both the accepted direct-reaction measurements and the low-energy Coulomb dissociation study of Iwasa et al. performed at about 50 A MeV. (orig.)
A mechanical connector design for high-current, high-coulomb pulsed power systems
Energy Technology Data Exchange (ETDEWEB)
Susoeff, A.R.; Hawke, R.S.; Leighton, K.S.
1992-02-25
A technique to make reliable high-current, high-coulomb electrical contact was developed for transmitting power into railguns. The method uses spring loaded removable connectors that are installed independently from the launcher. The simple rod-type design and absence of fastener holes allow maximum utilization of material mechanical properties. Repeated experiments with 9.5-mm diameter connectors demonstrated reliable pulsed charge transfer of 200 coulombs at currents of over 400kA. 20 refs.
One-Step Direct Return Method For Mohr-Coulomb Plasticity
DEFF Research Database (Denmark)
Clausen, Johan; Damkilde, Lars; Andersen, Lars
2004-01-01
A new return method for the Mohr-Coulomb yield criteria is presented. The idea is to transform the problem into the principal direction and thereby achieve very simple formulas for calculating the elastic return stresses.......A new return method for the Mohr-Coulomb yield criteria is presented. The idea is to transform the problem into the principal direction and thereby achieve very simple formulas for calculating the elastic return stresses....
One-Step Direct Return Method For Mohr-Coulomb Plasticity
DEFF Research Database (Denmark)
Clausen, Johan; Damkilde, Lars; Andersen, Lars
2004-01-01
A new return method for the Mohr-Coulomb yield criteria is presented. The idea is to transform the problem into the principal direction and thereby achieve very simple formulas for calculating the elastic return stresses.......A new return method for the Mohr-Coulomb yield criteria is presented. The idea is to transform the problem into the principal direction and thereby achieve very simple formulas for calculating the elastic return stresses....
On the Klein-Gordon oscillator subject to a Coulomb-type potential
Bakke, K.; Furtado, C.
2015-04-01
By introducing the scalar potential as modification in the mass term of the Klein-Gordon equation, the influence of a Coulomb-type potential on the Klein-Gordon oscillator is investigated. Relativistic bound states solutions are achieved to both attractive and repulsive Coulomb-type potentials and the arising of a quantum effect characterized by the dependence of angular frequency of the Klein-Gordon oscillator on the quantum numbers of the system is shown.
Near barrier scattering of 8He on 208Pb
Directory of Open Access Journals (Sweden)
Marquínez-Durán G.
2014-03-01
Full Text Available The exotic nucleus 8He is investigated by means of the measurement of the angular distributions of the elastic channel and the 6He and 4He fragment yields produced in the collision with a 208Pb target at two energies around the Coulomb barrier, 16 and 22 MeV. The experiment was performed at the GANIL-SPIRAL facility, with the aim of extracting information about the structure of 8He and the relevant reaction mechanisms. In this contribution, details of the experimental setup and preliminary data on elastic cross sections are reported.
Coulomb fission in multiply charged molecular clusters: Experiment and theory
Harris, Christopher; Baptiste, Joshua; Lindgren, Eric B.; Besley, Elena; Stace, Anthony J.
2017-04-01
A series of three multiply charged molecular clusters, (C6H6)nz+ (benzene), (CH3CNnz) + (acetonitrile), and (C4H8O)nz+ (tetrahydrofuran), where the charge z is either 3 or 4, have been studied for the purpose of identifying the patterns of behaviour close to the charge instability limit. Experiments show that on a time scale of ˜10-4 s, ions close to the limit undergo Coulomb fission where the observed pathways exhibit considerable asymmetry in the sizes of the charged fragments and are all associated with kinetic (ejection) energies of between 1.4 and 2.2 eV. Accurate kinetic energies have been determined through a computer simulation of peak profiles recorded in the experiments and the results modelled using a theory formulated to describe how charged particles of dielectric materials interact with one another [E. Bichoutskaia et al., J. Chem. Phys. 133, 024105 (2010)]. The calculated electrostatic interaction energy between separating fragments gives an accurate account for the measured kinetic energies and also supports the conclusion that +4 ions fragment into +3 and +1 products as opposed to the alternative of two +2 fragments. This close match between the theory and experiment reinforces the assumption that a significant fraction of excess charge resides on the surfaces of the fragment ions. It is proposed that the high degree of asymmetry seen in the fragmentation patterns of the multiply charged clusters is due, in part, to limits imposed by the time window during which observations are made.
Distributional sources for Newman's holomorphic Coulomb field
Energy Technology Data Exchange (ETDEWEB)
Kaiser, Gerald [Center for Signals and Waves, Austin, TX (United States)
2004-09-10
Newman (1973 J. Math. Phys. 14 102-3) considered the holomorphic extension E-tilde(z) of the Coulomb field E(x) in R{sup 3}. From an analysis of its multipole expansion, he concluded that the real and imaginary parts E(x+iy){identical_to}Re E-tilde(x+iy), H(x+iy){identical_to}Im E-tilde(x+iy), viewed as functions of x, are the electric and magnetic fields generated by a spinning ring of charge R. This represents the EM part of the Kerr-Newman solution to the Einstein-Maxwell equations (Newman E T and Janis A I 1965 J. Math. Phys. 6 915-7; Newman E T et al 1965 J. Math. Phys. 6 918-9). As already pointed out in Newman and Janis (1965 J. Math. Phys. 6 915-7), this interpretation is somewhat problematic since the fields are double-valued. To make them single-valued, a branch cut must be introduced so that R is replaced by a charged disc D having R as its boundary. In the context of curved spacetime, D becomes a spinning disc of charge and mass representing the singularity of the Kerr-Newman solution. Here we confirm the above interpretation of E and H without resorting to asymptotic expansions, by computing the charge and current densities directly as distributions in R{sup 3} supported in D. This will show that D spins rigidly at the critical rate so that its rim R moves at the speed of light.
Yang-Mills theory in Coulomb gauge; Yang-Mills-theorie in Coulombeichung
Energy Technology Data Exchange (ETDEWEB)
Feuchter, C.
2006-07-01
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.)
Strong-field ionization via high-order Coulomb corrected strong-field approximation
Klaiber, Michael; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z; Keitel, Christoph H
2016-01-01
Signatures of the Coulomb corrections in the photoelectron momentum distribution during laser-induced ionization of atoms or ions in tunneling and multiphoton regimes are investigated analytically in the case of an one-dimensional problem. High-order Coulomb corrected strong-field approximation is applied, where the exact continuum state in the S-matrix is approximated by the eikonal Coulomb-Volkov state including the second-order corrections to the eikonal. Although, without high-order corrections our theory coincides with the known analytical R-matrix (ARM) theory, we propose a simplified procedure for the matrix element derivation. Rather than matching the eikonal Coulomb-Volkov wave function with the bound state as in the ARM-theory to remove the Coulomb singularity, we calculate the matrix element via the saddle-point integration method as by time as well as by coordinate, and in this way avoiding the Coulomb singularity. The momentum shift in the photoelectron momentum distribution with respect to the A...
Institute of Scientific and Technical Information of China (English)
LIU Jian-Ye; GUO Wen-Jun; XING Yong-Zhong; Li Xi-Guo
2004-01-01
We investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. We also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section.In this case, Coulomb interaction does not change obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential.
Alharbi, Abdulrazaq M.
2016-05-06
Various methods and systems are provided for smart parking barriers. In one example, among others, a smart parking barrier system includes a movable parking barrier located at one end of a parking space, a barrier drive configured to control positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking space and a second position that allows access to the parking space. The parking controller can initiate movement of the movable parking barrier in response to a positive identification of an individual allowed to use the parking space. The parking controller can identify the individual through, e.g., a RFID tag, a mobile device (e.g., a remote control, smartphone, tablet, etc.), an access card, biometric information, or other appropriate identifier.
Royer, G.; Zhang, H. F.
2008-01-01
International audience; The synthesis of superheavy elements has advanced strongly recently and their main observed decay mode is alpha emission. Predictions of alpha decay half-lives of other possible superheavy nuclei are needed. The alpha decay potential barrier is often described using a finite square well for the one-body shapes plus an hyperbola for the Coulomb repulsion between the alpha particle and its daughter. An arbitrary adjustment of the parameters allows to reproduce roughly th...
Coulomb-influenced collisions in aerosols and dusty plasmas.
Gopalakrishnan, Ranganathan; Hogan, Christopher J
2012-02-01
In aerosol and dusty plasma systems, the behavior of suspended particles (grains) is often strongly influenced by collisions occurring between ions and particles, as well as between particles themselves. In determining the collision kernel or collision rate coefficient for such charged entities, complications arise in that the collision process can be completely described neither by continuum transport mechanics nor by free molecular (ballistic) mechanics; that is, collisions are transition regime processes. Further, both the thermal energy and the potential energy between colliding entities can strongly influence the collision rate and must be considered. Flux-matching theory, originally developed by Fuchs, is frequently applied for calculation of collision rate coefficients under these circumstances. However, recent work suggests that crucial assumptions in flux-matching theory are not appropriate to describe transition regime collisions in the presence of potential interactions. Here, we combine dimensional analysis and mean first passage time calculations to infer the collision kernel between dilute charged entities suspended in a light background gas at thermal equilibrium. The motion of colliding entities is described by a Langevin equation, and Coulombic interactions are considered. It is found that the dimensionless collision kernel for these conditions, H, is a function of the diffusive Knudsen number, Kn(D) (in contrast to the traditional Knudsen number), and the potential energy to thermal energy ratio, Ψ(E). For small and large Kn(D), it is found that the dimensionless collision kernels inferred from mean first passage time calculations collapse to the appropriate continuum and free molecular limiting forms, respectively. Further, for repulsive collisions (Ψ(E) negative) or attractive collisions with Ψ(E)0.5, it is found that flux-matching theory predictions substantially underestimate the collision kernel. We find that the collision process in this
Direct evidence for a Coulombic phase in monopole-suppressed SU(2) lattice gauge theory
Energy Technology Data Exchange (ETDEWEB)
Grady, Michael, E-mail: grady@fredonia.edu
2013-11-21
Further evidence is presented for the existence of a non-confining phase at weak coupling in SU(2) lattice gauge theory. Using Monte Carlo simulations with the standard Wilson action, gauge-invariant SO(3)–Z2 monopoles, which are strong-coupling lattice artifacts, have been seen to undergo a percolation transition exactly at the phase transition previously seen using Coulomb gauge methods, with an infinite lattice critical point near β=3.2. The theory with both Z2 vortices and monopoles and SO(3)–Z2 monopoles eliminated is simulated in the strong-coupling (β=0) limit on lattices up to 60{sup 4}. Here, as in the high-β phase of the Wilson-action theory, finite size scaling shows it spontaneously breaks the remnant symmetry left over after Coulomb gauge fixing. Such a symmetry breaking precludes the potential from having a linear term. The monopole restriction appears to prevent the transition to a confining phase at any β. Direct measurement of the instantaneous Coulomb potential shows a Coulombic form with moderately running coupling possibly approaching an infrared fixed point of α∼1.4. The Coulomb potential is measured to 50 lattice spacings and 2 fm. A short-distance fit to the 2-loop perturbative potential is used to set the scale. High precision at such long distances is made possible through the use of open boundary conditions, which was previously found to cut random and systematic errors of the Coulomb gauge fixing procedure dramatically. The Coulomb potential agrees with the gauge-invariant interquark potential measured with smeared Wilson loops on periodic lattices as far as the latter can be practically measured with similar statistics data.
Direct evidence for a Coulombic phase in monopole-suppressed SU(2) lattice gauge theory
Grady, Michael
2013-11-01
Further evidence is presented for the existence of a non-confining phase at weak coupling in SU(2) lattice gauge theory. Using Monte Carlo simulations with the standard Wilson action, gauge-invariant SO(3)-Z2 monopoles, which are strong-coupling lattice artifacts, have been seen to undergo a percolation transition exactly at the phase transition previously seen using Coulomb gauge methods, with an infinite lattice critical point near β=3.2. The theory with both Z2 vortices and monopoles and SO(3)-Z2 monopoles eliminated is simulated in the strong-coupling (β=0) limit on lattices up to 604. Here, as in the high-β phase of the Wilson-action theory, finite size scaling shows it spontaneously breaks the remnant symmetry left over after Coulomb gauge fixing. Such a symmetry breaking precludes the potential from having a linear term. The monopole restriction appears to prevent the transition to a confining phase at any β. Direct measurement of the instantaneous Coulomb potential shows a Coulombic form with moderately running coupling possibly approaching an infrared fixed point of α˜1.4. The Coulomb potential is measured to 50 lattice spacings and 2 fm. A short-distance fit to the 2-loop perturbative potential is used to set the scale. High precision at such long distances is made possible through the use of open boundary conditions, which was previously found to cut random and systematic errors of the Coulomb gauge fixing procedure dramatically. The Coulomb potential agrees with the gauge-invariant interquark potential measured with smeared Wilson loops on periodic lattices as far as the latter can be practically measured with similar statistics data.
Comparison of COULOMB-2, NASCAP-2k and SPIS codes for geostationary spacecrafts charging
Novikov, Lev; Makletsov, Andrei; Sinolits, Vadim
In developing of international standards for spacecraft charging, it is necessary to compare results of spacecraft charging modeling obtained with various models. In the paper, electrical potentials for spacecraft 3D models were calculated with COULOMB-2, NASCAP-2k [1] and SPIS [2] software, and the comparison of obtained values was performed. To compare COULOMB-2 and NASCAP-2k codes we used a 3D geometrical model of a spacecraft given in [1]. Parameters of spacecraft surface materials were taken from [1], too. For COULOMB-2 and SPIS cross validation, we carried out calculations with SPIS code through SPENVIS web-interface and with COULOMB-2 software for a spacecraft geometrical model given in SPIS test examples [2]. In both cases, we calculated distributions of electric potentials on the spacecraft surface and visualized the obtained distributions with color code. Pictures of the surface potentials distribution calculated with COULOMB-2 and SPIS software are in good qualitative agreement. Absolute values of surface potentials calculated with these codes for different plasma conditions, are close enough. Pictures of the surface potentials distribution calculated for the spacecraft model [1] with COULOMB-2 software completely correspond to actual understanding of physical mechanisms of differential spacecraft surface charging. In this case, we compared only calculated values of the surface potential for the same space plasma conditions because the potential distributions on the spacecraft surface are absent in [1]. For all the plasma conditions considered, COULOMB-2 model gives higher absolute values of negative potential, than NASCAP-2k model. Differences in these values reach 2-3 kV. The possible explanations of the divergences indicated above are distinctions in calculation procedures of primary plasma currents and secondary emission currents. References 1. Ferguson D.С., Wimberly S.C. 51st AIAA Aerospace Science Meeting 2013 (AIAA 2013-0810). 2. http://dev.spis.org/projects/spine/home/spis
Directory of Open Access Journals (Sweden)
Eremenko V.
2016-01-01
Full Text Available The repulsive Coulomb force poses severe challenges when describing (d, p reactions for highly charged nuclei as a three-body problem. Casting Faddeev-AGS equations in a Coulomb basis avoids introducing screening of the Coulomb force. However, momentum space partial-wave t-matrix elements need to be evaluated in this basis. When those t-matrices are separable, the evaluation requires the folding of a form factor, depending on one momentum variable, with a momentum space partial-wave Coulomb function, which has a singular behavior at the external momentum q. We developed an improved regularization scheme to calculate Coulomb distorted form factors as the integral over the Coulomb function and complex nuclear form factors.
Eremenko, V; Elster, Ch; Nunes, F M; Thompson, I J; Arbanas, G; Escher, J E
2015-01-01
The repulsive Coulomb force poses severe challenges when describing $(d, p)$ reactions for highly charged nuclei as a three-body problem. Casting Faddeev-AGS equations in a Coulomb basis avoids introducing screening of the Coulomb force. However, momentum space partial-wave $t$-matrix elements need to be evaluated in this basis. When those $t$-matrices are separable, the evaluation requires the folding of a form factor, depending on one momentum variable, with a momentum space partial-wave Coulomb function, which has a singular behavior at the external momentum $q$. We developed an improved regularization scheme to calculate Coulomb distorted form factors as the integral over the Coulomb function and complex nuclear form factors.
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P. [P G Department of Physics and Research Centre, Payyanur College, Payyanur-670327 (India)], E-mail: drkpsanthosh@gmail.com; Bobby Jose, V. [P G Department of Physics and Research Centre, Payyanur College, Payyanur-670327 (India); Joseph, Antony; Varier, K.M. [Department of Physics, University of Calicut, Calicut-673635 (India)
2009-02-01
The fusion excitation functions and barrier distributions for the fusion of {sup 12}C, {sup 16}O, {sup 28}Si and {sup 35}Cl on {sup 92}Zr have been calculated using one-dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential. Calculated results are compared with experimental data and CC calculations using code CCFULL. At and above the barrier the computed cross sections match well with the experimental data, whereas below the barrier, calculations with nuclear surface tension coefficient improved by Reisdorf in the proximity potential give good fit. Reduced reaction cross sections for the systems have also been described.
DEFF Research Database (Denmark)
Duijm, Nijs Jan
2007-01-01
are discussed. A simple method for quantification of safety-barrier diagrams is proposed, including situations where safety barriers depend on shared common elements. It is concluded that safety-barrier diagrams provide a useful framework for an electronic data structure that integrates information from risk......Safety-barrier diagrams and the related so-called "bow-tie" diagrams have become popular methods in risk analysis. This paper describes the syntax and principles for constructing consistent and valid safety-barrier diagrams. The relation with other methods such as fault trees and Bayesian networks...... analysis with operational safety management....
Energy Technology Data Exchange (ETDEWEB)
Engelhardt, Netta; Wall, Aron C. [Department of Physics, University of California,Santa Barbara, CA 93106 (United States)
2014-03-13
We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy.
{sup 12}C+{sup 16}O: Properties of sub-barrier resonance {gamma}-decay
Energy Technology Data Exchange (ETDEWEB)
Goasduff, A.; Courtin, S.; Haas, F.; Lebhertz, D.; Jenkins, D. G.; Fallis, J.; Ruiz, C.; Hutcheon, D. A.; Amandruz, P.-A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G. [Universite de Strasbourg, IPHC, 23 rue du Loess 67037 Strasbourg (France) and CNRS, UMR7178, 67037 Strasbourg (France); GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)
2012-10-20
In a recent experiment performed at Triumf using the Dragon 0 Degree-Sign spectrometer and its associated BGO array, the complete {gamma}-decay of the radiative capture channel below the Coulomb barrier has been measured for the first time. This measurement has been performed at two energies E{sub c.m.}= 6.6 and 7.2 MeV. A selective contribution of the entrance spins 2{sup +} and 3{sup -} has been evidenced which is consistent with existing results above the barrier.
Hamiltonian Approach to 1+1 dimensional Yang-Mills theory in Coulomb gauge
Reinhardt, H
2008-01-01
We study the Hamiltonian approach to 1+1 dimensional Yang-Mills theory in Coulomb gauge, considering both the pure Coulomb gauge and the gauge where in addition the remaining constant gauge field is restricted to the Cartan algebra. We evaluate the corresponding Faddeev-Popov determinants, resolve Gauss' law and derive the Hamiltonians, which differ in both gauges due to additional zero modes of the Faddeev-Popov kernel in the pure Coulomb gauge. By Gauss' law the zero modes of the Faddeev-Popov kernel constrain the physical wave functionals to zero colour charge states. We solve the Schroedinger equation in the pure Coulomb gauge and determine the vacuum wave functional. The gluon and ghost propagators and the static colour Coulomb potential are calculated in the first Gribov region as well as in the fundamental modular region, and Gribov copy effects are studied. We explicitly demonstrate that the Dyson-Schwinger equations do not specify the Gribov region while the propagators and vertices do depend on the ...
On the Coulomb effect in laser-assisted proton scattering by a stationary atomic nucleus
Hrour, E.; Taj, S.; Chahboune, A.; El Idrissi, M.; Manaut, B.
2017-06-01
In the framework of the first Born approximation, we investigate the scenario where in addition to a laser field, a nuclear Coulomb field is also present to affect a proton. We work in the approximation in which the proton is considered to be a structureless spin 1/2 Dirac particle with a mass m p . Furthermore, in the laboratory system, the fixed nucleus is treated as a point-like Coulomb potential. In the presence of a laser field, and taking into account the Coulomb effect, the proton will be described by distorted Dirac-Volkov wave functions. The introduction of the Coulomb effect to both the incident and scattered proton will enhance the relativistic differential cross sections (RDCSs). Regarding the physical picture, it is found that for the various kinetic energies of the incident proton, the Coulomb effect can be neglected at high kinetic energies in this particular geometry. Therefore, Dirac-Volkov states are largely sufficient to describe the laser-dressed protons. The behavior of the various RDCSs versus the atomic number Z is also presented.
Three-Body Coulomb Functions in the Hyperspherical Adiabatic Expansion Method
Garrido, E.; Kievsky, A.; Viviani, M.
2016-10-01
In this work we describe a numerical method devised to compute continuum three-body wave functions. The method is implemented using the hyperspherical adiabatic expansion for the three-body wave function imposing a box boundary condition. The continuum energy spectrum results discretized and, for specific quantum number values, all the possible incoming and outgoing channels are simultaneously computed. For a given energy, the hyperradial continuum functions form a matrix whose ij-term refers to specific incoming and outgoing channels. When applied to three-body systems interacting only through the Coulomb potential, this method provides the adiabatic representation of the regular three-body Coulomb wave function. The computation of the irregular Coulomb wave function representation is also discussed. These regular and irregular Coulomb functions can be used to extract the {S} -matrix for those reactions where, together with some short-range potential, the Coulomb interaction is also present. The method is illustrated in the case of the 3→ 3 process of three alpha particles.
Anoukou, K.; Pastor, F.; Dufrenoy, P.; Kondo, D.
2016-06-01
The present two-part study aims at investigating the specific effects of Mohr-Coulomb matrix on the strength of ductile porous materials by using a kinematic limit analysis approach. While in the Part II, static and kinematic bounds are numerically derived and used for validation purpose, the present Part I focuses on the theoretical formulation of a macroscopic strength criterion for porous Mohr-Coulomb materials. To this end, we consider a hollow sphere model with a rigid perfectly plastic Mohr-Coulomb matrix, subjected to axisymmetric uniform strain rate boundary conditions. Taking advantage of an appropriate family of three-parameter trial velocity fields accounting for the specific plastic deformation mechanisms of the Mohr-Coulomb matrix, we then provide a solution of the constrained minimization problem required for the determination of the macroscopic dissipation function. The macroscopic strength criterion is then obtained by means of the Lagrangian method combined with Karush-Kuhn-Tucker conditions. After a careful analysis and discussion of the plastic admissibility condition associated to the Mohr-Coulomb criterion, the above procedure leads to a parametric closed-form expression of the macroscopic strength criterion. The latter explicitly shows a dependence on the three stress invariants. In the special case of a friction angle equal to zero, the established criterion reduced to recently available results for porous Tresca materials. Finally, both effects of matrix friction angle and porosity are briefly illustrated and, for completeness, the macroscopic plastic flow rule and the voids evolution law are fully furnished.
Energy Technology Data Exchange (ETDEWEB)
Singh, D., E-mail: dsinghiuac@gmail.com [Centre for Applied Physics, Central University of Jharkhand, Ranchi-835 205 (India); Ali, R. [Department of Physics, G.F.(P.G.), College, Shahjahanpur-242 001 (India); Kumar, Harish; Ansari, M. Afzal [Department of Physics, Aligarh Muslim University, Aligarh-202 002 (India); Rashid, M. H.; Guin, R. [Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata-700 064 (India)
2014-08-14
Experiment has been performed to explore the complete and incomplete fusion dynamics in heavy ion collisions using stacked foil activation technique. The measurement of excitation functions of the evaporation residues produced in the {sup 20}Ne+{sup 165}Ho system at projectile energies ranges ≈ 4-8 MeV/nucleon have been done. Measured cumulative and direct cross-sections have been compared with the theoretical model code PACE-2, which takes into account only the complete fusion process. The analysis indicates the presence of contributions from incomplete fusion processes in some α-emission channels following the break-up of the projectile {sup 20}Ne in the nuclear field of the target nucleus {sup 165}Ho.
Energy Technology Data Exchange (ETDEWEB)
Acosta, L.; Martel, I.; Perez-Bernal, F.; Rodriguez, D.; Sanchez-Benitez, A.M. [Universidad de Huelva, Departamento de Fisica Aplicada, Huelva (Spain); Alvarez, M.A.G.; Gomez-Camacho, J. [Universidad de Sevilla, Departamento de Fisica Atomica Molecular y Nuclear, Sevilla (Spain); Universidad de Sevilla-CSIC-Junta de Andalucia, Centro Nacional de Aceleradores, Sevilla (Spain); Andres, M.V.; Espino, J.M.; Moro, A.M.; Mukha, I. [Universidad de Sevilla, Departamento de Fisica Atomica Molecular y Nuclear, Sevilla (Spain); Borge, M.J.G.; Cortes, M.; Galaviz, D.; Maira, A.; Reillo, E.; Tengblad, O. [CSIC, Madrid, Instituto de Estructura de la Materia, Madrid (Spain); Rusek, K. [The Andrzej Soltan Institute for Nuclear Studies, Warsaw (Poland)
2009-12-15
The angular distribution for {sup 11}Be+{sup 120}Sn quasielastic scattering at E{sub lab}=32 MeV was measured at REX-ISOLDE, CERN. The interpretation of the data in terms of coupled-channel calculations suggests a strong coupling with the p-states lying in the continuum. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Morcelle, V.; Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Faria, P.N.; Camargo, O.; Barioni, A.; Mendes Junior, D.R.; Condori, R. P.; Zamora, J.C.; Morais, M.C.; Pires, K.C.C.; Scarduelli, V.; Leistenschneider, E.; Zagatto, V.A.B. [Universidade de Sao Paulo (USP), SP (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Aguilera, E.F.; Martinez-Quiroz, E.; Lizcano, D. [Instituto Nacional de Investigaciones Nucleares, DF (Mexico); Kolata, J.; Lamm, L.O. [University of Notre Dame, Indiana (United States); Becchetti, F.; Jiang, H. [University of Michigan, Ann Arbor, MI (United States)
2011-07-01
Full text: The advent of radioactive beam production opened a new era in the nuclear physics, allowing the study of nuclei far from the beta stability line. One of the most interesting discoveries is the exotic structure of some of these unstable nuclei, which present the halo, such as {sup 6}He, {sup 11}Be, {sup 11}Li and others. During the last years, systems involving the neutron halo nuclei {sup 6}He have been extensively studied. In the case proton halo nuclei, on the other hand, the amount of available experimental data is very limited. The proton rich nucleus {sup 8}B is very interesting candidate as it has one proton very loosely bound (Sp = 138 KeV) to the {sup 7}Be core. Due to this low binding energy, the {sup 8}B is expected to be a proton halo and the dissociation {sup 8}B -- >{sup 7}Be+p in a collision {sup 8}B+target is expected to be very probable having a considerable effect in the total reaction cross section. We performed {sup 8}B+{sup 27}Al elastic scattering measurements at E{sub lab}= 16.0 and 22.0 MeV. The {sup 8}B beam has been produced by the reaction {sup 3}He({sup 6}Li,{sup 8}B)n and focused on a {sup 27}Al secondary target (2.1 mg/cm{sup 2}). Two experiments have been performed one at the RIBRAS system (Brazil) and another in Twinsol (USA). As the secondary beam is a cocktail of {sup 4}He, {sup 6}Li, {sup 7}Be, {sup 8}B particles, the {sup 7}Be+{sup 27}Al elastic angular distributions have been obtained as well. The elastic angular distributions were analyzed by optical model calculations, using Woods- Saxon potential and the total reaction cross sections have been obtained. The total reaction cross sections have been reduced using the Wong formula and the UFF equation being compared with others data from the literature. (author)
Multinucleon transfer in the interaction of /sup 58/Ni with /sup 124/Sn around the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Chiodi, I.; Lunardi, S.; Morando, M.; Signorini, C. (Padua Univ. (Italy). Ist. di Fisica; Istituto Nazionale di Fisica Nucleare, Padua (Italy)); Fortuna, G.; Starzecki, W.; Stefanini, A.M. (Istituto Nazionale di Fisica Nucleare, Padua (Italy). Lab. di Legnaro); Korschinek, G.; Morinaga, H.
1982-02-06
Relative cross-sections for 1, 2, 3, (4, 5) neutron pick-up from a /sup 124/Sn target were measured at THETAsub(l)sub(a)sub(b)=70/sup 0/ with a /sup 58/Ni beam energy of 249 MeV; pairing correlations in the two interacting nuclei and kinematical effects strongly affect the cross-sections; the possibility of observing coherent multipair transfer is discussed.
Surface absorption in the {sup 32}S+{sup 24}Mg interactions at energies near the Coulomb barrier
Energy Technology Data Exchange (ETDEWEB)
Pacheco, J.C.; Sanchez, F.; Diaz, J.; Ferrero, J.L. [Valencia Univ. (Spain); Bilwes, B. [Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Ruiz, J.A. [Universidad Publica de Navarra, Pamplona (Spain); Kadi-Hanifi, D. [Universite de Blida (Algeria)
1995-12-31
Elastic scattering {sup 32} S on {sup 24} Mg has been measured at 65.0, 75.0, 86.3, 95.0 and 110.0 MeV-lab energies, and the data were systematically analysed with semi-phenomenological potentials. Using microscopic potentials we found similar results at the lowest incident energies, for which we have compared both the microscopic and semi-phenomenological potentials. It appears that the absorption takes place in a narrow range at the nuclear surface and is mainly due to the low lying collective surface states. (author). 41 refs., 11 figs., 4 tabs.
Stefanescu, I.; Chilug, A.; Tudor, D.; Trache, L.; Straticiuc, M.; Burducea, I.; Focsa, I. M.; Ghita, D. G.; Zhang, N.; Tang, X.; Chen, H.
2017-06-01
The reaction cross section of the 12C+12C system is difficult to measure because of the presence of the resonances in the Gamow energy window. It has been proved that the 13C+12C reaction is a good alternative to study the behavior of the reaction cross section at energies relevant for astrophysics. We have measured it with activation and online techniques. During online measurements we were interested to determine the relative contributions of the open channels of the 13C+12C reaction. These determinations are necessary to evaluate the total fusion reaction cross section. Therefore, we have measured the γ-ray yields of proton, neutron and alpha particle evaporation channels from the resulting 25Mg compound nucleus using prompt γ-rays measurements. This complements the activation method. The irradiations took place at the 3 MV Tandetron Accelerator at IFIN-HH [1], Bucharest and the prompt gamma-rays were measured using a hyper-pure germanium detector with 100% relative efficiency, shielded with lead bricks. The energy range for the irradiation was from 4.6 up to 11 MeV (in laboratory frame), in steps of 0.2 MeV and the online measurements were performed from 6.4 up to 11 MeV.
Wilcox, Bethany R; Pepper, Rachel E; Pollock, Steven J
2012-01-01
Utilizing the integral expression of Coulomb's Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulomb's Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of t...
Enhanced Bulk-Edge Coulomb Coupling in Fractional Fabry-Perot Interferometers.
von Keyserlingk, C W; Simon, S H; Rosenow, Bernd
2015-09-18
Recent experiments use Fabry-Perot (FP) interferometry to claim that the ν=5/2 quantum Hall state exhibits non-Abelian topological order. We note that the experiments appear inconsistent with a model neglecting bulk-edge Coulomb coupling and Majorana tunneling, so we reexamine the theory of FP devices. Even a moderate Coulomb coupling may strongly affect some fractional plateaus, but very weakly affect others, allowing us to model the data over a wide range of plateaus. While experiments are consistent with the ν=5/2 state harboring Moore-Read topological order, they may have measured Coulomb effects rather than an "even-odd effect" due to non-Abelian braiding.
Exchange effects in Coulomb quantum plasmas: Dispersion of waves in 2D and 3D mediums
Andreev, Pavel A
2014-01-01
We describe quantum hydrodynamic equations with the Coulomb exchange interaction for three and two dimensional plasmas. Explicit form of the force densities are derived. We present non-linear Schrodinger equations (NLSEs) for the Coulomb quantum plasmas with the exchange interaction. We show contribution of the exchange interaction in the dispersion of the Langmuir, and ion-acoustic waves. We consider influence of the spin polarization ratio on strength of the Coulomb exchange interaction. This is important since exchange interaction between particles with same spin direction and particles with opposite spin directions are different. At small particle concentrations $n_{0}>10^{25}cm^{-3}$ the Fermi pressure prevails over the exchange interaction for all polarizations. Similar picture we obtain for two dimensional quantum plasmas.
Singh, P.; Kharb, S.; Singh, M.
2014-02-01
The effects of electric quadrupole ( E2) and dipole-quadrupole interference ( E1- E2) terms in the Coulomb breakup of 15C have been investigated within the framework of eikonal approximation. The sensitivity of Coulomb breakup cross section, differential in relative energy and Longitudinal Momentum Distribution (LMD) of core fragments, towards these terms have been examined. A very small (1% of E1) contribution of E2 transition has been predicted in integrated Coulomb breakup cross section. Further it is also found that the inclusion of E2 and E1- E2 terms introduces a small asymmetry in the peak of relative energy spectrum and also increases the peak height of the spectrum. The contribution of dipole-quadrupole interference terms is clearly shown in LMD, as it introduces an asymmetry in the shape of LMD and enhances the matching between the data and predictions.
Coexistence and competition of on-site and intersite Coulomb interactions in Mott-molecular-dimers
Juliano, R. C.; de Arruda, A. S.; Craco, L.
2016-02-01
We reveal the interplay between on-site (U) and intersite (V) Coulomb interactions in the extended two-site Hubbard model. Due to its atomic-like form quantum correlations intrinsic to Mott-molecular-dimers are exactly computed. Our results for physical quantities such as double occupancy and specific heat are consistent with those obtained for the one-band Hubbard model, suggesting that a two-site dimer model is able to capture the essential thermodynamic properties of strongly interacting electron systems. It is noted that intersite Coulomb interactions promote the formation of doublons, which compete with the spin-singlet state induced by the on-site Coulomb repulsion. Our results are expected to be relevant for understanding electronic and thermodynamical properties of interacting electrons in systems with strongly coupled magnetic atoms.
Coulomb excitation of neutron-deficient polonium isotopes studied at ISOLDE
Neven, Michiel
The polonium isotopes represent an interesting region of the nuclear chart having only two protons outside the Z = 82 closed shell. These isotopes have already been extensively studied theoretically and experimentally. The heavier isotopes (A > 200) seem to follow a "regular seniority-type regime" while for the lighter isotopes (A < 200) a more collective behavior is observed. Many questions remain regarding the transition between these two regimes and the configuration mixing between quantum states. Experiments in the lighter polonium isotopes point to the presence of shape coexistence, however the phenomenon is not fully understood. A Coulomb excitation study of the polonium isotopes whereby the dynamic properties are investigated can provide helpful insights in understanding the shape coexistence phenomena. In this thesis $^{202}$Po was studied via Coulomb excitation. The $^{202}$Po isotope was part of an experimental campaign in which the $^{196,198,200,206}$Po isotopes were studied as well via Coulomb...
Low rank factorization of the Coulomb integrals for periodic coupled cluster theory
Hummel, Felix; Grüneis, Andreas
2016-01-01
We study the decomposition of the Coulomb integrals of periodic systems into a tensor contraction of six matrices of which only two are distinct. We find that the Coulomb integrals can be well approximated in this form already with small matrices compared to the number of real space grid points. The cost of computing the matrices scales as O(N^4) using a regularized form of the alternating least squares algorithm. The studied factorization of the Coulomb integrals can be exploited to reduce the scaling of the computational cost of expensive tensor contractions appearing in the amplitude equations of coupled cluster methods with respect to system size. We apply the developed methodologies to calculate the adsorption energy of a single water molecule on a hexagonal boron nitride monolayer in a plane wave basis set and periodic boundary conditions.
Treating Coulomb exchange contributions in relativistic mean field calculations: why and how
Van Giai, Nguyen; Gu, Huai-Qiang; Long, Wenhui; Meng, Jie
2014-01-01
The energy density functional (EDF) method is very widely used in nuclear physics, and among the various existing functionals those based on the relativistic Hartree (RH) approximation are very popular because the exchange contributions (Fock terms) are numerically rather onerous to calculate. Although it is possible to somehow 'mock up' the effects of meson-induced exchange terms by adjusting the meson-nucleon couplings, the lack of Coulomb exchange contributions hampers the accuracy of predictions. In this note, we show that the Coulomb exchange effects can be easily included with a good accuracy in a perturbative approach. Therefore, it would be desirable for future relativistic EDF models to incorporate Coulomb exchange effects, at least to some order of perturbation.
Chakraborty, Baishali; Sen, Siddhartha
2012-01-01
We study the combined effect of a conical topological defect and a Coulomb charge impurity on the dynamics of Dirac fermions in gapped graphene. Beyond a certain strength of the Coulomb charge, quantum instability sets in, which demarcates the boundary between sub and supercritical values of the charge. In the subcritical regime, for certain values of the system parameters, the allowed boundary conditions in gapped graphene cone can be classified in terms of a single real parameter. We show that the observables such as local density of states, scattering phase shifts and the bound state spectra are sensitive to the value of this real parameter, which is interesting from an empirical point of view. For a supercritical Coulomb charge, we analyze the system with a regularized potential as well as with a zigzag boundary condition and find the effect of the sample topology on the observable features of the system.
On the Klein–Gordon oscillator subject to a Coulomb-type potential
Energy Technology Data Exchange (ETDEWEB)
Bakke, K., E-mail: kbakke@fisica.ufpb.br; Furtado, C., E-mail: furtado@fisica.ufpb.br
2015-04-15
By introducing the scalar potential as modification in the mass term of the Klein–Gordon equation, the influence of a Coulomb-type potential on the Klein–Gordon oscillator is investigated. Relativistic bound states solutions are achieved to both attractive and repulsive Coulomb-type potentials and the arising of a quantum effect characterized by the dependence of angular frequency of the Klein–Gordon oscillator on the quantum numbers of the system is shown. - Highlights: • Interaction between the Klein–Gordon oscillator and a modified mass term. • Relativistic bound states for both attractive and repulsive Coulomb-type potentials. • Dependence of the Klein–Gordon oscillator frequency on the quantum numbers. • Relativistic analogue of a position-dependent mass system.
Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics
Quan, Wei; Hao, Xiaolei; Chen, Yongju; Yu, Shaogang; Xu, Songpo; Wang, Yanlan; Sun, Renping; Lai, Xuanyang; Wu, Chengyin; Gong, Qihuang; He, Xiantu; Liu, Xiaojun; Chen, Jing
2016-06-01
In strong field atomic physics community, long-range Coulomb interaction has for a long time been overlooked and its significant role in intense laser-driven photoelectron dynamics eluded experimental observations. Here we report an experimental investigation of the effect of long-range Coulomb potential on the dynamics of near-zero-momentum photoelectrons produced in photo-ionization process of noble gas atoms in intense midinfrared laser pulses. By exploring the dependence of photoelectron distributions near zero momentum on laser intensity and wavelength, we unambiguously demonstrate that the long-range tail of the Coulomb potential (i.e., up to several hundreds atomic units) plays an important role in determining the photoelectron dynamics after the pulse ends.
Analysis of Spent Nuclear Fuel Imaging Using Multiple Coulomb Scattering of Cosmic Muons
Chatzidakis, Stylianos; Tsoukalas, Lefteri H
2016-01-01
Cosmic ray muons passing through matter lose energy from inelastic collisions with electrons and are deflected from nuclei due to multiple Coulomb scattering. The strong dependence of scattering on atomic number Z and the recent developments on position sensitive muon detectors indicate that multiple Coulomb scattering could be an excellent candidate for spent nuclear fuel imaging. Muons present significant advantages over existing monitoring and imaging techniques and can play a central role in monitoring nuclear waste and spent nuclear fuel stored in dense well shielded containers. The main purpose of this paper is to investigate the applicability of multiple Coulomb scattering for imaging of spent nuclear fuel dry casks stored within vertical and horizontal commercial storage dry casks. Calculations of muon scattering were performed for various scenarios, including vertical and horizontal fully loaded dry casks, half loaded dry casks, dry casks with one row of fuel assemblies missing, dry casks with one fu...
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.
Spin and the Coulomb gap in the half-filled lowest Landau level
Eisenstein, J. P.; Khaire, T.; Nandi, D.; Finck, A. D. K.; Pfeiffer, L. N.; West, K. W.
2016-09-01
The Coulomb gap observed in tunneling between parallel two-dimensional electron systems, each at half-filling of the lowest Landau level, is found to depend sensitively on the presence of an in-plane magnetic field. Especially at low electron density, the width of the Coulomb gap at first increases sharply with in-plane field, but then abruptly levels off. This behavior appears to coincide with the known transition from partial to complete spin polarization of the half-filled lowest Landau level. The tunneling gap therefore opens a window onto the spin configuration of two-dimensional electron systems at high magnetic field.
Geometric constraints on the space of N=2 SCFTs III: enhanced Coulomb branches and central charges
Argyres, Philp; Lü, Yongchao; Martone, Mario
2016-01-01
This is the third in a series of three papers on the systematic analysis of rank 1 four dimensional $\\mathcal{N}=2$ SCFTs. In the first two papers we developed and carried out a strategy for classifying and constructing physical planar rank-1 Coulomb branch geometries of $\\mathcal{N}=2$ SCFTs. Here we describe general features of the Higgs and mixed branch geometries of the moduli space of these SCFTs, and use this, along with their Coulomb branch geometry, to compute their conformal and flavor central charges. We conclude with a summary of the state of the art for rank-1 $\\mathcal{N}=2$ SCFTs.
Hamiltonian approach to QCD in Coulomb gauge at zero and finite temperature
Directory of Open Access Journals (Sweden)
Reinhardt H.
2017-01-01
Full Text Available I report on recent results obtained within the Hamiltonian approach to QCD in Coulomb gauge. By relating the Gribov confinement scenario to the center vortex picture of confinement it is shown that the Coulomb string tension is tied to the spatial string tension. For the quark sector a vacuum wave functional is used which results in variational equations which are free of ultraviolet divergences. The variational approach is extended to finite temperatures by compactifying a spatial dimension. For the chiral and deconfinement phase transition pseudo-critical temperatures of 170MeV and 198 MeV, respectively, are obtained.
Institute of Scientific and Technical Information of China (English)
陈建新; 马日; 任海振; 李霞; 杨宏; 龚旗煌
2003-01-01
Laser-induced Coulomb explosion of CO is studied experimentally using differently polarized femtosecond laser pulses of 2 × 1015 W/cm2 intensity at λ = 800 nm. The channels of molecular Coulomb explosion are observed to be independent of the laser polarizations. The critical distance R is deduced to be larger for the circularly polarized light in comparison with the linearly polarized light. The initial emissions of C+, C2+, O+, and O2+ions are anisotropic for linear polarization and isotropic for circular polarization. The suppression of ionization occurs for the elliptically and circularly polarized lasers.
Effect of Coulomb Interaction on Dynamical Localization in a Two-Electron Quantum-Dot Molecule
Institute of Scientific and Technical Information of China (English)
WANG Li-Min; DUAN Su-Qing; ZHAO Xian-Geng; LIU Cheng-Shi
2004-01-01
The combined interaction of Coulomb interaction and ac fields with two electrons in a quantum dot molecule is studied respectively with numerical simulation, perturbation theory and the approximation of driven two-level model. The dynamical localization occurs with the ac field whose ratio of the amplitude to the angular frequency is a root of n-order Bessel functions, where n is determined by the Coulomb interaction energy. Such results are explained with either the driven two-level approximation or the degenerated three-level model and verified by the numerical simulations.
Observation of a structural transition for coulomb crystals in a linear Paul trap
DEFF Research Database (Denmark)
Kjærgaard, N.; Drewsen, M.
2003-01-01
A structural transition for laser cooled ion Coulomb crystals in a linear Paul trap just above the stability limit of parametrically resonant excitation of bulk plasma modes has been observed. In contrast to the usual spheroidal shell structures present below the stability limit, the ions arrange...... in a "string-of-disks" configuration. The spheroidal envelopes of the string-of-disks structures are in agreement with results from cold fluid theory usually valid for ion Coulomb crystals if the ion systems are assumed to be rotating collectively....
Effects of the Lorentz invariance violation in Coulomb interaction in nuclei and atoms
Flambaum, V V
2016-01-01
Anisotropy in the speed of light (studied in the Michelson-Morley experiment ) generates anisotropy in the Coulomb interaction. This anisotropy manifests itself in the nuclear and atomic experiments. The experimental results for 21Ne are used to improve the limits on the tensor components characterising the asymmetry of the speed of light and the Coulomb interaction (violation of the Lorentz symmetry in the photon sector) by 7 orders of magnitude in comparison with previous experiments: the speed of light is isotropic to a part in 10E-28.
Directory of Open Access Journals (Sweden)
Ye Ning
2015-12-01
Full Text Available In the present work, we report calculations of resonances in the positron-hydrogen system interacting with screened Coulomb potentials using the method of complex scaling together with employing correlated Hylleraas wave functions. Resonances with natural and unnatural parities are investigated. For the natural parity case, resonance parameters (energy and width for D-wave resonance states with even parity lying below various positronium and hydrogen thresholds up to the H(N = 4 level are determined. For the unnatural parity case, results for P-even and D-odd resonance states with various screened Coulomb interaction strengths are located below different lower-lying Ps and H thresholds.
Effects of the Lorentz Invariance Violation on Coulomb Interactions in Nuclei and Atoms
Flambaum, V. V.; Romalis, M. V.
2017-04-01
Anisotropy in the speed of light that has been constrained by Michelson-Morley-type experiments also generates anisotropy in the Coulomb interactions. This anisotropy can manifest itself as an energy anisotropy in nuclear and atomic experiments. Here the experimental limits on Lorentz violation in Ne2110 are used to improve the limits on Lorentz symmetry violations in the photon sector, namely, the anisotropy of the speed of light and the Coulomb interactions, by 7 orders of magnitude in comparison with previous experiments: the speed of light is isotropic to a part in 10-28.
Limits on Lorentz Invariance Violation from Coulomb Interactions in Nuclei and Atoms.
Flambaum, V V; Romalis, M V
2017-04-07
Anisotropy in the speed of light that has been constrained by Michelson-Morley-type experiments also generates anisotropy in the Coulomb interactions. This anisotropy can manifest itself as an energy anisotropy in nuclear and atomic experiments. Here the experimental limits on Lorentz violation in _{10}^{21}Ne are used to improve the limits on Lorentz symmetry violations in the photon sector, namely, the anisotropy of the speed of light and the Coulomb interactions, by 7 orders of magnitude in comparison with previous experiments: the speed of light is isotropic to a part in 10^{28}.
Braverman, Alexander; Nakajima, Hiraku
2016-01-01
Consider the $3$-dimensional $\\mathcal N=4$ supersymmetric gauge theory associated with a compact Lie group $G_c$ and its quaternionic representation $\\mathbf M$. Physicists study its Coulomb branch, which is a noncompact hyper-K\\"ahler manifold with an $\\mathrm{SU}(2)$-action, possibly with singularities. We give a mathematical definition of the Coulomb branch as an affine algebraic variety with $\\mathbb C^\\times$-action when $\\mathbf M$ is of a form $\\mathbf N\\oplus\\mathbf N^*$, as the second step of the proposal given in arXiv:1503.03676.
On the role of the Coulomb potential in strong field atomic ionization dynamics
Energy Technology Data Exchange (ETDEWEB)
Tetchou Nganso, H.M. [Laboratoire de Physique Atomique, Moleculaire et Optique (PAMO), Universite Catholique de Louvain, 2 Chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium)], E-mail: htetchou@yahoo.com; Giraud, S. [Ecole Normale Superieure de Cachan, Antenne de Bretagne, Avenue Robert Schuman, Campus de Ker Lann, F-35170 Bruz (France); Piraux, B. [Laboratoire de Physique Atomique, Moleculaire et Optique (PAMO), Universite Catholique de Louvain, 2 Chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium); Popov, Yu.V. [Nuclear Physics Institute, Moscow State University, Moscow 119992 (Russian Federation); Kwato Njock, M.G. [Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ), Faculty of Science, University of Douala, P.O. Box 8580 Douala (Cameroon)
2007-10-15
In this paper, we present a model aimed at exploring the role of the Coulomb potential in the mechanism of ionization of atomic hydrogen exposed to a strong low frequency pulsed laser field. Our approach is based on the solution of the time-dependent Schroedinger equation in momentum space. Although we are in a frequency and intensity regime where tunnelling is expected to dominate, our results indicate that the atomic structure associated to the Coulomb potential plays a significant role for low energy ejected electrons.
Role of Nuclear Coulomb Attraction in Nonsequential Double Ionization of Argon Atom
Institute of Scientific and Technical Information of China (English)
汤清彬; 张东玲; 李盈傧; 余本海
2011-01-01
The microscopic recollision dynamics in strong-field nonsequential double ionization of Ar atoms is in- vestigated using three-dimensional classical ensembles. By adjusting the nuclear Coulomb potential, we can excellently reproduce the experimental results both within the laser intensity regimes well above the reeollision threshold and well below the recollision threshold quantitatively. More importantly, our trajectory analysis clearly reveals the particular electronic dynamics in recollision process： the momentum of the recolliding electron encounters a sudden change both in magnitude and in direction when it approaches the nucleus closely, which show that the nuclear Coulomb attraction plays a key role in the recollision process of nonsequential double ionization of Ar atoms.
Hamiltonian approach to QCD in Coulomb gauge at zero and finite temperature
Reinhardt, H; Campagnari, D; Ebadati, E; Heffner, J; Quandt, M; Vastag, P; Vogt, H
2016-01-01
I report on recent results obtained within the Hamiltonian approach to QCD in Coulomb gauge. By relating the Gribov confinement scenario to the center vortex picture of confinement it is shown that the Coulomb string tension is tied to the spatial string tension. For the quark sector a vacuum wave functional is used which results in variational equations which are free of ultraviolet divergences. The variational approach is extended to finite temperatures by compactifying a spatial dimension. For the chiral and deconfinement phase transition pseudo-critical temperatures of 170 MeV and 198 MeV, respectively, are obtained.
A shortcut through the Coulomb gas method for spectral linear statistics on random matrices
Deelan Cunden, Fabio; Facchi, Paolo; Vivo, Pierpaolo
2016-04-01
In the last decade, spectral linear statistics on large dimensional random matrices have attracted significant attention. Within the physics community, a privileged role has been played by invariant matrix ensembles for which a two-dimensional Coulomb gas analogy is available. We present a critical revision of the Coulomb gas method in random matrix theory (RMT) borrowing language and tools from large deviations theory. This allows us to formalize an equivalent, but more effective and quicker route toward RMT free energy calculations. Moreover, we argue that this more modern viewpoint is likely to shed further light on the interesting issues of weak phase transitions and evaporation phenomena recently observed in RMT.
Energy Technology Data Exchange (ETDEWEB)
Kolenda, Stefan; Wolf, Michael J.; Beckmann, Detlef [Institut fuer Nanotechnologie, KIT, 76021 Karlsruhe (Germany)
2013-07-01
In normalmetal/superconductor hybrid structures nonlocal conductance is determined by crossed Andreev reflection (CAR) and elastic cotunneling (EC). This was investigated recently both experimentally and theoretically. Dynamical Coulomb blockade of EC and CAR was predicted theoretically. Here we report on experimental investigations of these effects. We found signatures of dynamical Coulomb blockade in local and nonlocal conductance in the normal state. In the superconducting state, we find s-shaped nonlocal differential conductance curves as a function of bias applied on both contacts. These curves were observed for bias voltages both below and above the gap. We compare our results to theory.
On the drift mobility of a molecular polaron in the presence of Coulomb traps
Rackovsky, S.; Scher, H.
1999-08-01
We study the drift mobility of a molecular polaron in the presence of an external applied field and Coulomb traps. The model is based on one previously developed for geminate recombination of photogenerated charge carriers. It is shown that the unusual combination of Poole-Frenkel-like field dependence and non-Arrhenius temperature dependence of the mobility, measured experimentally in molecular films, is well reproduced by this model. Our key result is that this nearly universal experimental behavior of the mobility arises from competition between rates of polaron trapping and release from a very low density of Coulomb traps.
Strong-field S -matrix theory with final-state Coulomb interaction in all orders
Faisal, F. H. M.
2016-09-01
During the last several decades the so-called Keldysh-Faisal-Reiss or strong-field approximation (SFA) has been highly useful for the analysis of atomic and molecular processes in intense laser fields. However, it is well known that SFA does not account for the final-state Coulomb interaction which is, however, unavoidable for the ubiquitous ionization process. In this Rapid Communication we solve this long-standing problem and give a complete strong-field S -matrix expansion that accounts for the final-state Coulomb interaction in all orders, explicitly.
Dynamic gap generation in graphene under the long-range Coulomb interaction
Energy Technology Data Exchange (ETDEWEB)
Wang Jingrong; Liu Guozhu, E-mail: wangjr@mail.ustc.edu.cn, E-mail: gzliu@ustc.edu.cn [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui, 230026 (China)
2011-08-31
Dynamic gap generation in graphene under the long-range Coulomb interaction is studied by the Dyson-Schwinger gap equation beyond the instantaneous approximation. Once the dependence of the dynamic gap on the energy has been considered, the critical interaction strength {alpha}{sub c} decreases to 0.542. If the renormalization of the fermion velocity is considered, {alpha}{sub c} will become {alpha}{sub c} = 1.02. This indicates that the dependence on the energy and the renormalization of the fermion velocity are both important for dynamic gap generation in graphene under long-range Coulomb interaction. (paper)
Numerical Study of Coulomb Scattering Effects on Electron Beamfrom a Nano-Tip
Energy Technology Data Exchange (ETDEWEB)
Qiang, Ji; Corlett, John N.; Lidia, Steven M.; Padmore, HowardA.; Wan, Weishi; Zholent, Andrew A.; Zolotorev, Max
2007-06-25
Nano-tips with high acceleration gradient around the emission surface have been proposed to generate high brightness beams. However, due to the small size of the tip, the charge density near the tip is very high even for a small number of electrons. The stochastic Coulomb scattering near the tip can degrade the beam quality and cause extra emittance growth and energy spread. In the paper, we present a numerical study of these effects using a direct relativistic N-body model. We found that emittance growth and energy spread, due to Coulomb scattering, can be significantly enhanced with respect to mean-field space-charge calculations.
Mesoscopic fluctuations of Coulomb drag between quasiballistic one-dimensional wires
DEFF Research Database (Denmark)
Mortensen, Asger; Flensberg, Karsten; Jauho, Antti-Pekka
2002-01-01
Quasiballistic one-dimensional quantum wires are known to have a conductance of the order of 2e(2)/h, with small sample-to-sample fluctuations. We present a study of the transconductance G(12) Of two Coulomb-coupled quasiballistic wires; i.e., we consider the Coulomb drag geometry. We show...... that the fluctuations in G(12) differ dramatically from those of the diagonal conductance G(ii): the fluctuations are large and can even exceed the mean value, thus implying a possible reversal of the induced drag current. We report extensive numerical simulations elucidating the fluctuations for both correlated...
Dimension two condensates in the Gribov-Zwanziger theory in the Coulomb gauge
Guimaraes, M S; Sorella, S P
2015-01-01
We investigate the dimension two condensate $$ within the Gribov-Zwanziger approach to Euclidean Yang-Mills theories in the Coulomb gauge, in both 3 and 4 dimensions. An explicit calculation shows that, at the first order, the condensate $$ is plagued by a non-integrable IR divergence in 3D, while in 4D it exhibits a logarithmic UV divergence, being proportional to the Gribov parameter $\\gamma^2$. These results indicate that in 3D the transverse spatial Coulomb gluon two-point correlation function exhibits a scaling behaviour, in agreement with Gribov's expression. In 4D, however, they suggest that, next to the scaling behaviour, a decoupling solution might emerge too.
Fusion excitation function measurement for 6Li+64Ni at near-barrier energies
Directory of Open Access Journals (Sweden)
Shaikh Md. Moin
2015-01-01
Full Text Available Total fusion excitation function has been measured for the reaction of weakly bound 6Li projectile on medium mass 64Ni target at energies near the Coulomb barrier of the system. Online characteristic γ-ray detection method has been used to identify and determine the cross sections of the residues. No suppression of total fusion cross section (σTF is observed at above barrier energies. But enhancement of measured cross section with respect to the one-dimensional barrier penetration model (1-DBPM calculation is observed at below barrier energies. The enhancement can not be explained by coupled channels calculation with dominant projectile and target excitations as well as one-neutron stripping reaction.
Barriers to screening mammography.
Sarma, Elizabeth A
2015-01-01
Breast cancer (BRCA) is the second most commonly diagnosed cancer among women in the USA, and mammography is an effective means for the early detection of BRCA. Identifying the barriers to screening mammography can inform research, policy and practice aiming to increase mammography adherence. A literature review was conducted to determine common barriers to screening mammography adherence. PsycINFO and PubMed databases were searched to identify studies published between 2000 and 2012 that examined barriers associated with reduced mammography adherence. Three thematic groups of barriers, based on social ecology, were identified from the literature: healthcare system-level, social and individual-level barriers. Researchers must consider screening behaviour in context and, therefore, should simultaneously consider each level of barriers when attempting to understand screening behaviour and create interventions to increase mammography adherence.
O-16 Coulomb dissociation : towards a new means to determine the C-12+alpha fusion rate in stars
Fleurot, F; van den Berg, AM; Davids, B; Harakeh, MN; Kravchuk, VL; Wilschut, HW; Guillot, J; Laurent, H; Willis, A; Assuncao, M; Kiener, J; Lefebvre, A; de Sereville, N; Tatischeff, [No Value; Assuncao, L.; Lefebvre, L.; Tafischeff, V.
2005-01-01
A feasibility study was made of an important aspect of the Coulomb-dissociation method, which has been proposed for the determination of the rate of the astrophysically important C-12(alpha, gamma)160 reaction. A crucial aspect is the disentanglement of nuclear and Coulomb interactions on one hand a
Richter, Martin; Schöffler, Markus; Jahnke, Till; Schmidt, Lothar Ph H; Dörner, Reinhard
2016-01-01
We report on electron momentum distributions from single ionization of Ar in strong orthogonally polarized two-color (OTC) laser fields measured with the COLTRIMS technique. We study the effect of Coulomb focusing whose signature is a cusp like feature in the center of the electron momentum spectrum. While the direct electrons show the expected strong dependence on the phase between the two colors, surprisingly the Coulomb focused structure is almost not influenced by the weak second harmonic streaking field. This effect is explained by the use of a CTMC simulation which describes the tunneled electron wave packet in terms of classical trajectories under the influence of the combined Coulomb- and OTC laser field. We find a subtle interplay between the initial momentum of the electron upon tunneling, the ionization phase and the action of the Coulomb field that makes the Coulomb focused part of the momentum spectrum apparently insensitive to the weaker streaking field.
A practical calculational method for treating Coulomb scattering in momentum space
Energy Technology Data Exchange (ETDEWEB)
Elster, Ch. (Ohio Univ., Athens, OH (United States). Dept. of Physics and Astronomy); Liu, L.C. (Los Alamos National Lab., NM (United States)); Thaler, R.M. (Los Alamos National Lab., NM (United States) Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics)
1993-12-01
An exact and practical numerical procedure for treating the Coulomb interaction in momentum-space calculations of elastic scattering of charged particles is presented. The method is tested for various interactions over a wide charge, energy and angular momentum range and found to be accurate. (Author).
Strong Coulomb scattering effects on low frequency noise in monolayer WS2 field-effect transistors
Joo, Min-Kyu; Yun, Yoojoo; Yun, Seokjoon; Lee, Young Hee; Suh, Dongseok
2016-10-01
When atomically thin semiconducting transition metal dichalcogenides are used as a channel material, they are inevitably exposed to supporting substrates. This situation can lead to masking of intrinsic properties by undesired extrinsic doping and/or additional conductance fluctuations from the largely distributed Coulomb impurities at the interface between the channel and the substrate. Here, we report low-frequency noise characteristics in monolayer WS2 field-effect transistors on silicon/silicon-oxide substrate. To mitigate the effect of extrinsic low-frequency noise sources, a nitrogen annealing was carried out to provide better interface quality and to suppress the channel access resistance. The carrier number fluctuation and the correlated mobility fluctuation (CNF-CMF) model was better than the sole CNF one to explain our low-frequency noise data, because of the strong Coulomb scattering effect on the effective mobility caused by carrier trapping/detrapping at oxide traps. The temperature-dependent field-effect mobility in the four-probe configuration and the Coulomb scattering parameters are presented to support this strong Coulomb scattering effect on carrier transport in monolayer WS2 field-effect transistor.
On-shell and half-shell effects of the coulomb potential in quantum mechanics
Maag, Jan Willem de
1984-01-01
In dit proefschrift wordt de Coulomb potentiaal in de nietrelativistische quantummechanica bestudeerd. Met gebruik van een streng wiskundige beschrijving onderzoeken we, in het bijzonder, on-shell en off-shell eigenschappen. De overeenkomsten en de verschillen met het geval van een glad afgeschermde
Comment on an application of the asymptotic iteration method to a perturbed Coulomb model
Energy Technology Data Exchange (ETDEWEB)
Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal DIaz del Castillo 340, Colima (Mexico); Fernandez, Francisco M [INIFTA (Conicet, UNLP), Blvd. 113 y 64 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)
2006-08-18
We discuss a recent application of the asymptotic iteration method (AIM) to a perturbed Coulomb model. Contrary to what was argued before we show that the AIM converges and yields accurate energies for that model. We also consider alternative perturbation approaches and show that one of them is equivalent to that recently proposed by another author.
Boundary States and Correlation Functions of Tricritical Ising Model from Coulomb-Gas Formalism
Institute of Scientific and Technical Information of China (English)
Smain Balaska; Toufik Sahabi
2009-01-01
We consider the minimal conformal model describing the tricritical Ising model on the disk and on the upper half plane. Using the coulomb-gas formalism we determine its consistents boundary states as well as its one-point and two-point correlation functions.
Can Coulomb Sturmians Be Used as a Basis for N-Electron Molecular Calculations?
DEFF Research Database (Denmark)
Avery, John Scales; Avery, James Emil
2009-01-01
A method is proposed for using isoenergetic configurations formed from many-center Coulomb Sturmians as a basis for calculations on N-electron molecules. Such configurations are solutions to an approximate N-electron Schrödinger equation with a weighted potential, and they are thus closely analog...
Coulomb explosion of CS2 molecule under an intense femtosecond laser field
Xiao, Wang; Jian, Zhang; Shi-An, Zhang; Zhen-Rong, Sun
2016-05-01
We experimentally demonstrate the Coulomb explosion process of CS2 molecule under a near-infrared (800 nm) intense femtosecond laser field by a DC-sliced ion imaging technique. We obtain the DC-sliced images of these fragment ions S+, S2+, CS+, and CS2+ by breaking one C-S bond, and assign their Coulomb explosion channels by considering their kinetic energy release and angular distribution. We also numerically simulate the dissociation dynamics of parent ions by a Coulomb potential approximation, and obtain the time evolution of Coulomb energy and kinetic energy release, which indicates that the dissociation time of parent ions decreases with the increase of the charge number k. These experimental and theoretical results can serve as a useful benchmark for those researchers who work in the related area. Project supported by the National Natural Science Foundation of China (Grant Nos. 51132004 and 11474096), and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14JC1401500). We acknowledge the support of the NYU-ECNU Institute of Physics at NYU Shanghai, China.
The First Principle Formula of the Relativistic Heat Conductivity of Coulomb Electronic Plasmas
Institute of Scientific and Technical Information of China (English)
TIAN Chu-Shun; ZHANG Chi; LU Quan-Kang
2001-01-01
Making use of the relativistic BBGKY technique,the relativistic generalization of Landau collision integral is obtained.Furthermore,we calculate the relativistic hydrodynamic modes up to the second order in the hydrodynamic wave number.Combining Résibois' method,we present the first principle formula of the relativistic heat conductivity of Coulomb electronic plasmas for low-order corrections.
Pseudospin, Spin, and Coulomb Dirac-Symmetries: Doublet Structure and Supersymmetric Patterns
Leviatan, A
2005-01-01
Relativistic symmetries of the Dirac Hamiltonian with a mixture of spherically symmetric Lorentz scalar and vector potentials, are examined from the point of view of supersymmetric quantum mechanics. The cases considered include the Coulomb, pseudospin and spin limits relevant, respectively, to atoms, nuclei and hadrons.
Zhang, Jie
2014-01-01
Based on the plenty method, this paper describes a numerical method for 2D non-smooth contact problems with Coulomb friction and bilateral constraints and its application to the simulation of statics and dynamics for a frictional translational joint. Comparison is made with results obtained using a finite element program, ANSYS.
Spatial structure of the modified Coulomb potential in a superstrong magnetic field
Glazyrin, S I
2016-01-01
The modification of the Coulomb potential due to the enhancement of loop corrections in a superstrong magnetic field is studied numerically. We calculate the modified potential with high precision and obtain the pattern of equipotential lines. The results confirm the general features known from previous studies, however we emphasize some differences in potential structure that can be important for problems with spatially distributed charges.
Cavity electromagnetically induced transparency and all-optical switching using ion Coulomb crystals
DEFF Research Database (Denmark)
Albert, Magnus; Dantan, Aurelien Romain; Drewsen, Michael
2011-01-01
nonlinear interactions, such as those based on electromagnetic induced transparency (EIT)2, 3, 4, 5, 6, 9, 10, 11, 12. Here, we demonstrate for the first time EIT as well as all-optical EIT-based light switching using ion Coulomb crystals situated in an optical cavity. Changes from essentially full...
GEOMETRIC OPTICS FOR 3D-HARTREE-TYPE EQUATION WITH COULOMB POTENTIAL
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
This article considers a family of 3D-Hartree-type equation with Coulomb potential |x|-1, whose initial data oscillates so that a caustic appears. In the linear geometric optics case, by using the Lagrangian integrals, a uniform description of the solution outside the caustic, and near the caustic are obtained.
Coulomb drag: a probe of electron interactions in coupled quantum wells
DEFF Research Database (Denmark)
Jauho, Antti-Pekka
1996-01-01
calculations lead to several predictions of effects not yet seen experimentally We conclude that Coulomb drag, in particular when combined with magnetic fields, is a very versatile tool for directly probing interparticle interactions in dimensionally restricted systems. A further line for research could...
The interplay of nuclear and Coulomb effects in proton breakup from exotic nuclei
Kumar, Ravinder
2012-01-01
This paper gives new insight to the study of dynamical effects in proton breakup as compared to neutron breakup from a weakly bound state in an exotic nucleus. Following our recent work [Ravinder Kumar and Angela Bonaccorso, Phys. Rev. C84 014613 (2011)] there has been some discussion in the literature [B. Paes, J. Lubiana, P.R.S. Gomes, V. Guimar\\~aes, Nucl. Phys. A890 1 (2012); Y. Kucuk and A. M. Moro, Phys. Rev. C86 034601 (2012)], thus in order to clarify and asses quantitatively which mechanism would dominate measured observables, we study here several reaction mechanisms separately but also their total including interference. These mechanisms are: the recoil effect of the core-target Coulomb potential which we distinguish from the direct proton-target Coulomb potential and nuclear breakup, which consists of stripping and diffraction. Direct Coulomb breakup typically gives cross sections about an order of magnitude larger than the recoil term and the amount of nuclear diffraction vs. Coulomb depends on t...
The problem of true macroscopic charge quantization in the Coulomb blockade
Burmistrov, I.S.; Pruisken, A.M.M.; Bonča, J.; Kruchinin, S.
2008-01-01
Based on the Ambegaokar-Eckern-Schön approach to the Coulomb blockade we develop a complete quantum theory of the single electron transistor. We identify a previously unrecognized physical observable in the problem that, unlike the usual average charge on the island, is robustly quantized for any fi
An su(1, 1) algebraic approach for the relativistic Kepler-Coulomb problem
Energy Technology Data Exchange (ETDEWEB)
Salazar-Ramirez, M; Granados, V D [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, Ed. 9, Unidad Profesional Adolfo Lopez Mateos, 07738 Mexico DF (Mexico); MartInez, D [Universidad Autonoma de la Ciudad de Mexico, Plantel Cuautepec, Av. La Corona 320, Col. Loma la Palma, Delegacion Gustavo A. Madero, 07160 Mexico DF (Mexico); Mota, R D, E-mail: dmartinezs77@yahoo.com.m [Unidad Profesional Interdisciplinaria de Ingenieria y TecnologIas Avanzadas, IPN. Av. Instituto Politecnico Nacional 2580, Col. La Laguna Ticoman, Delegacion Gustavo A. Madero, 07340 Mexico DF (Mexico)
2010-11-07
We apply the Schroedinger factorization method to the radial second-order equation for the relativistic Kepler-Coulomb problem. From these operators we construct two sets of one-variable radial operators which are realizations for the su(1, 1) Lie algebra. We use this algebraic structure to obtain the energy spectrum and the supersymmetric ground state for this system.
Self-adjoint extensions of Coulomb systems in 1,2 and 3 dimensions
de Oliveira, Cesar R
2008-01-01
We study the nonrelativistic quantum Coulomb hamiltonian (i.e., inverse of distance potential) in $R^n$, n = 1, 2, 3. We characterize their self-adjoint extensions and, in the unidimensional case, present a discussion of controversies in the literature, particularly the question of the permeability of the origin. Potentials given by fundamental solutions of Laplace equation are also briefly considered.
Coulomb-Modified Fano Resonance in a One-Lead Quantum Dot
DEFF Research Database (Denmark)
Johnson, Anna Ansaba; M. Marcus, C.; Hanson, Mats
2003-01-01
We investigate a tunable Fano interferometer consisting of a quantum dot coupled via tunneling to a one-dimensional channel. In addition to Fano resonance, the channel shows strong Coulomb response to the dot, with a single electron modulating channel conductance by factors of up to 100. Where...
Coulomb Correction to the Screening Angle of the Moliere Multiple Scattering Theory
Kuraev, E A; Tarasov, A V
2012-01-01
Coulomb correction to the screening angular parameter of the Moliere multiple scattering theory is found. Numerical calculations are presented in the range of nuclear charge from Z=4 to Z=82. Comparison with the approximate Moliere result for the screening angle reveals up to 30% deviation from it for sufficiently heavy elements of the target material.
Neutrino energy estimates from multiple Coulomb scattering of upthroughgoing muons in MACRO
Bakari, D; Giorgini, M; Spurio, M
2002-01-01
Summary form only given. Estimates of the energies of neutrino induced muons in MACRO were made by measuring the multiple Coulomb scattering (MCS) in the rock absorbers in the lower part of the MACRO detector. The deflections of muons inside the detector depend on the muon energy. (1 refs).
Unified Treatment of Screening Coulomb and Anharmonic Oscillator Potentials in Arbitrary Dimensions
Institute of Scientific and Technical Information of China (English)
Bülent G(o)nül; Okan (O)zer; Mehmet Ko(c)ak
2006-01-01
A mapping is obtained relating radial screened Coulomb systems with low screening parameters to radial anharmonic oscillators in N-dimensional space. Using the formalism of supersymmetric quantum mechanics, it is shown that exact solutions of these potentials exist when the parameters satisfy certain constraints.
Coulomb Explosion and Energy Loss of Energetic C_(20) Clusters in Dense Plasmas
Institute of Scientific and Technical Information of China (English)
WANG Gui-Qiu; LI Wen-Kun; WANG You-Nian
2009-01-01
The molecular dynamics(MD)method is used to simulate the interactions of energetic C_(20) clusters with the dense plasma targets within the framework of the linear Vlasov-Poisson theory.The influences of various clusters(H_2,N_2,C_(20) and C_(60) respectively)on stopping power are discussed.The simulation results show that the vicinage effects in the Coulomb explosion dynamics and the stopping power are strongly affected by the variations in the cluster speed and the plasma parameters.Coulomb explosions axe found to proceed faster for higher speeds,lower plasma densities and higher electron temperatures.In addition,the cluster stopping power is strongly enhanced in the early stages of Coulomb explosions due to the vicinage effect,but this enhancement eventually diminishes,after the cluster constituent ions are sufficiently separated.For the large and heavy clusters,the stopping power ratio reaches much higher values in the early stage of Coulomb explosion owing to the constructive interferences in the vicinage effect.
Application of finite field-dependent BRS transformations to problems of the Coulomb gauge
Joglekar, S D
2001-01-01
We discuss the Coulomb propagator in the formalism developed recently in which we construct the Coulomb gauge path-integral by correlating it with the well-defined Lorentz gauge path-integrals through a finite field-dependent BRS transformation. We discover several features of the Coulomb gauge from it. We find that the singular Coulomb gauge HAS to be treated as the gauge parameter lambda --> 0 limit. We further find that the propagator so obtained has good high energy behavior (k_0^{-2}) for lambda and epsilon nonzero. We further find that the behavior of the propagator so obtained is sensitive to the order of limits k_0 -->infinity, lambda -->0 and epsilon --> 0; so that these have to be handled carefully in a higher loop calculation. We show that we can arrive at the result of Cheng and Tsai for the ambiguous two loop Feynman integrals without the need for an extra ad hoc regularization and within the path integral formulation.
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...
Pumping of Vibrational Excitations in the Coulomb-Blockade Regime in a Suspended Carbon Nanotube
Hüttel, A.K.; Witkamp, B.; Leijnse, M.; Wegewijs, M.R.; Van der Zant, H.S.J.
2009-01-01
Low-temperature transport spectroscopy measurements on a suspended few-hole carbon nanotube quantum dot are presented, showing a gate-dependent harmonic excitation spectrum which, strikingly, occurs in the Coulomb-blockade regime. The quantized excitation energy corresponds to the scale expected for
A New Method for the Atomic Ground-State Energy in the Screened Coulomb Potential
Institute of Scientific and Technical Information of China (English)
YU Peng-Peng; GUO Hua
2001-01-01
The new method proposed recently by Friedberg,Lee and Zhao is applied to the derivation of the atomic ground-state energy with the inclusion of the screening effect.The present results are compared with those obtained in the pure Coulomb potential and by the variational approach.The overall good results are obtained with this new method.``
Dynamics of Braking Vehicles: From Coulomb Friction to Anti-Lock Braking Systems
Tavares, J. M.
2009-01-01
The dynamics of braking of wheeled vehicles is studied using the Coulomb approximation for the friction between road and wheels. The dependence of the stopping distance on the mass of the vehicle, on the number of its wheels and on the intensity of the braking torque is established. It is shown that there are two regimes of braking, with and…
Coulomb drag devices: electric solar wind sail propulsion and ionospheric deorbiting
Janhunen, Pekka
2014-01-01
A charged tether or wire experiences Coulomb drag when inserted into flowing plasma. In the solar wind the Coulomb drag can be utilised as efficient propellantless interplanetary propulsion as the electric solar wind sail (electric sail, E-sail). In low Earth orbit (LEO) the same plasma physical effect can be utilised for efficient low-thrust deorbiting of space debris objects (the plasma brake). The E-sail is rotationally stabilised while the deorbiting Coulomb drag devices According to numerical estimates, Coulomb drag devices have very promising performance figures, both for interplanetary propulsion and for deorbiting in LEO. Much of the technology is common to both applications. E-sail technology development was carried out in ESAIL FP7 project (2011-2013) which achieved TRL 4-5 for key hardware components that can enable 1 N class interplanetary E-sail weighing less than 200 kg. The thrust of the E-sail scales as inverse solar distance and its power consumption (nominally 700 W/N at 1 au) scales as the ...
The pushing gate in a planar Coulomb crystal using a flat-top laser beam
Energy Technology Data Exchange (ETDEWEB)
Kitaoka, M., E-mail: kitaoka@lyman.q.t.u-tokyo.ac.j [Department of Systems Innovation, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Buluta, I.M. [Department of Quantum Engineering and Systems Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Hasegawa, S., E-mail: hasegawa@sys.t.u-tokyo.ac.j [Department of Systems Innovation, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Quantum Engineering and Systems Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
2009-08-10
We propose a pushing gate for entangling two ions in a planar Coulomb crystal in the view of realizing large-scale quantum simulations. A tightly focused laser is irradiated from the direction perpendicular to the crystal plane and its spatial intensity profile generates a state-dependent force. We analyze the error sources in this scheme and obtain low infidelity.
On the integral representations of the Jost function and Coulomb off-shell Jost solution
Indian Academy of Sciences (India)
U Laha
2006-08-01
The integral representations of the Jost function (on- and off-shell) are rederived by the judicious use of the transposed operator relation on the particular integrals for Jost solution and using one of these particular integrals an analytical expression for the Coulomb off-shell Jost solution is presented in the maximal reduced form.
Coulomb blockade model of permeation and selectivity in biological ion channels
Kaufman, I. Kh; McClintock, P. V. E.; Eisenberg, R. S.
2015-08-01
Biological ion channels are protein nanotubes embedded in, and passing through, the bilipid membranes of cells. Physiologically, they are of crucial importance in that they allow ions to pass into and out of cells, fast and efficiently, though in a highly selective way. Here we show that the conduction and selectivity of calcium/sodium ion channels can be described in terms of ionic Coulomb blockade in a simplified electrostatic and Brownian dynamics model of the channel. The Coulomb blockade phenomenon arises from the discreteness of electrical charge, the strong electrostatic interaction, and an electrostatic exclusion principle. The model predicts a periodic pattern of Ca2+ conduction versus the fixed charge Qf at the selectivity filter (conduction bands) with a period equal to the ionic charge. It thus provides provisional explanations of some observed and modelled conduction and valence selectivity phenomena, including the anomalous mole fraction effect and the calcium conduction bands. Ionic Coulomb blockade and resonant conduction are similar to electronic Coulomb blockade and resonant tunnelling in quantum dots. The same considerations may also be applicable to other kinds of channel, as well as to charged artificial nanopores.
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...
Coulomb traction on a penny-shaped crack in a three dimensional piezoelectric body
Energy Technology Data Exchange (ETDEWEB)
Li, Qun; Kuna, Meinhard [TU Bergakademie Freiberg, Institute of Mechanics and Fluid Dynamics, Freiberg (Germany); Ricoeur, Andreas [University of Kassel, Institute of Mechanics, Kassel (Germany)
2011-06-15
The axisymmetric problem of a penny-shaped crack embedded in an infinite three-dimensional (3D) piezoelectric body is considered. A general formulation of Coulomb traction on the crack surfaces can be obtained based on thermodynamical considerations of electromechanical systems. Three-dimensional electroelastic solutions are derived by the classical complex potential theory when Coulomb traction is taken into account and the poling direction of piezoelectric body is perpendicular to the crack surfaces. Numerical results show that the magnitude of Coulomb tractions can be large, especially when a large electric field in connection with a small mechanical load is applied. Unlike the traditional traction-free crack model, Coulomb tractions induced by an applied electric field influence the Mode I stress intensity factor for a penny-shaped crack in 3D piezoelectric body. Moreover, compared to the current model, the traditional traction-free crack model always overestimates the effect of the applied electric load on the field intensity factors and energy release rates, which has consequences for 3D piezoelectric fracture mechanics. (orig.)
Coulomb-blockade transport in single-crystal organic thin-film transistors
Schoonveld, W. A.; Wildeman, J.; Fichou, D.; Bobbert, P. A.; van Wees, B. J.; Klapwijk, T. M.
2000-04-01
Coulomb-blockade transport-whereby the Coulomb interaction between electrons can prohibit their transport around a circuit-occurs in systems in which both the tunnel resistance, RT, between neighbouring sites is large (>>h/e2) and the charging energy, EC (EC = e2/2C, where C is the capacitance of the site), of an excess electron on a site is large compared to kT. (Here e is the charge of an electron, k is Boltzmann's constant, and h is Planck's constant.) The nature of the individual sites-metallic, superconducting, semiconducting or quantum dot-is to first order irrelevant for this phenomenon to be observed. Coulomb blockade has also been observed in two-dimensional arrays of normal-metal tunnel junctions, but the relatively large capacitances of these micrometre-sized metal islands results in a small charging energy, and so the effect can be seen only at extremely low temperatures. Here we demonstrate that organic thin-film transistors based on highly ordered molecular materials can, to first order, also be considered as an array of sites separated by tunnel resistances. And as a result of the sub-nanometre sizes of the sites (the individual molecules), and hence their small capacitances, the charging energy dominates at room temperature. Conductivity measurements as a function of both gate bias and temperature reveal the presence of thermally activated transport, consistent with the conventional model of Coulomb blockade.
Dirac-Coulomb scattering with plane wave energy eigenspinors on de Sitter expanding universe
Cotaescu, Ion I
2007-01-01
The lowest order contribution of the amplitude of Dirac-Coulomb scattering in de Sitter spacetime is calculated assuming that the initial and final states of the Dirac field are described by exact solutions of the free Dirac equation on de Sitter spacetime with a given energy and helicity. We find that the total energy is conserved in the scattering process.
Cherkis bow varieties and Coulomb branches of quiver gauge theories of affine type $A$
Nakajima, Hiraku
2016-01-01
We show that Coulomb branches of quiver gauge theories of affine type $A$ are Cherkis bow varieties, which have been introduced as ADHM type description of moduli space of instantons on the Taub-NUT space equivariant under a cyclic group action.
Stability of Coulomb crystals in a linear Paul trap with storage-ring-like confinement
DEFF Research Database (Denmark)
Kjærgaard, Niels; Mølhave, Kristian; Drewsen, Michael
2002-01-01
We report experiments on the stability of ion Coulomb crystals in a linear Paul trap with storage-ring-like confinement. The transverse dynamics of charged particles in a trap of this type is analogous to that of a fast beam traveling through a channel with periodic, magnetic alternating gradient...
Jerky-type phenomena at nanocomposite surfaces : The breakdown of the coulomb friction law
Hosson, Jeff T.M. De; Pei, Yutao; Chen, Changqiang
This article concentrates on the jerky-type phenomenon of surfaces in relative motion (i.e., a breakdown of the Coulomb friction law) in nanocomposite materials. Physical arguments are provided to understand the dependence of friction on sliding velocity in the sense of self-lubrication. Also
Coulomb breakup of B-8 and the flux of B-8 neutrinos from the Sun
Davids, B; Austin, SM; Bazin, D; Esbensen, H; Sherrill, BM; Thompson, IJ; Tostevin, JA
2002-01-01
A kinematically complete measurement was made of the Coulomb dissociation of 813 nuclei on a Pb target at 83 MeV/nucleon. The cross-section was measured at low relative energies in order to infer the astrophysical S-factor for the Be-7(p,gamma)B-8 reaction. A first-order perturbation theory analysis
Elastic and inelastic scattering of {sup 16}O+{sup 64}Zn at near-barrier energies
Energy Technology Data Exchange (ETDEWEB)
Tenreiro, C.; Acquadro, J.C.; Freitas, P.A.; Liguori Neto, R. [Universidade de Sao Paulo, IFUSP Laboratorio Pelletron, C.P. 20516-01498-970, Sao Paulo (Brazil); Ramirez, G.; Cuevas, N. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago 1 (Chile); Gomes, P.R.; Cabezas, R.; Anjos, R.M. [Departamento de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Niteroi, R. J., 24210 (Brazil); Copnell, J. [University of Manchester, Physics Department, Schuster Laboratories, Manchester M13 9PL (United Kingdom)
1996-06-01
Elastic and inelastic scattering angular distributions were measured for the {sup 16}O+{sup 64}Zn reaction at bombarding energies close to the Coulomb barrier. The experimental data were analyzed within the optical model and coupled-channel model. An extended dispersion relation of integral quantities using a Gaussian weight was applied, instead of the normal relationship. Within this frame, the optical model parameters obtained from the data are in agreement with the dispersion relation and show the threshold anomaly at energies close to the Coulomb barrier. Analysis of the inelastic scattering angular distributions leads to some indications that an inelastic threshold anomaly is beginning to develop at energies lower than the ones for which our data were taken. {copyright} {ital 1996 The American Physical Society.}
Converse Barrier Certificate Theorems
DEFF Research Database (Denmark)
Wisniewski, Rafael; Sloth, Christoffer
2016-01-01
This paper shows that a barrier certificate exists for any safe dynamical system. Specifically, we prove converse barrier certificate theorems for a class of structurally stable dynamical systems. Other authors have developed a related result by assuming that the dynamical system has neither sing...
DEFF Research Database (Denmark)
2016-01-01
Renowned experts present the latest knowledge Although a very fragile structure, the skin barrier is probably one of the most important organs of the body. Inward/out it is responsible for body integrity and outward/in for keeping microbes, chemicals, and allergens from penetrating the skin. Since...... the role of barrier integrity in atopic dermatitis and the relationship to filaggrin mutations was discovered a decade ago, research focus has been on the skin barrier, and numerous new publications have become available. This book is an interdisciplinary update offering a wide range of information...... on the subject. It covers new basic research on skin markers, including results on filaggrin and on methods for the assessment of the barrier function. Biological variation and aspects of skin barrier function restoration are discussed as well. Further sections are dedicated to clinical implications of skin...
Effect of long-range repulsive Coulomb interactions on packing structure of adhesive particles.
Chen, Sheng; Li, Shuiqing; Liu, Wenwei; Makse, Hernán A
2016-02-14
The packing of charged micron-sized particles is investigated using discrete element simulations based on adhesive contact dynamic model. The formation process and the final obtained structures of ballistic packings are studied to show the effect of interparticle Coulomb force. It is found that increasing the charge on particles causes a remarkable decrease of the packing volume fraction ϕ and the average coordination number 〈Z〉, indicating a looser and chainlike structure. Force-scaling analysis shows that the long-range Coulomb interaction changes packing structures through its influence on particle inertia before they are bonded into the force networks. Once contact networks are formed, the expansion effect caused by repulsive Coulomb forces are dominated by short-range adhesion. Based on abundant results from simulations, a dimensionless adhesion parameter Ad*, which combines the effects of the particle inertia, the short-range adhesion and the long-range Coulomb interaction, is proposed and successfully scales the packing results for micron-sized particles within the latest derived adhesive loose packing (ALP) regime. The structural properties of our packings follow well the recent theoretical prediction which is described by an ensemble approach based on a coarse-grained volume function, indicating some kind of universality in the low packing density regime of the phase diagram regardless of adhesion or particle charge. Based on the comprehensive consideration of the complicated inter-particle interactions, our findings provide insight into the roles of short-range adhesion and repulsive Coulomb force during packing formation and should be useful for further design of packings.
Gontchar, I. I.; Chushnyakova, M. V.
2016-08-01
Systematic calculations of the Coulomb barrier parameters for collisions of spherical nuclei are performed within the framework of the double folding approach. The value of the parameter {B}Z={Z}P{Z}T/({A}P{1/3}+{A}T{1/3}) (which estimates the Coulomb barrier height) varies in these calculations from 10 MeV up to 150 MeV. The nuclear densities came from the Hartree-Fock calculations which reproduce the experimental charge densities with good accuracy. For the nucleon-nucleon effective interaction two analytical approximations known in the literature are used: the M3Y and Migdal forces. The calculations show that Migdal interaction always results in the higher Coulomb barrier. Moreover, as B Z increases the difference between the M3Y and Migdal barrier heights systematically increases as well. As the result, the above barrier fusion cross sections calculated dynamically with the M3Y forces and surface friction are in agreement with the data. The cross sections calculated with the Migdal forces are always below the experimental data even without accounting for the dissipation.
Gontchar, Igor
2015-01-01
Systematic calculations of the Coulomb barrier parameters for collisions of spherical nuclei are performed within the framework of the double folding approach. The value of the parameter $B_Z=Z_PZ_T/(A^{1/3}_P+(A^{1/3}_P)$ (which estimates the Coulomb barrier height) varies in these calculations from 10 MeV up to 150 MeV. The nuclear densities came from the Hartree-Fock calculations which reproduce the experimental charge densities with good accuracy. For the nucleon-nucleon effective interaction two analytical approximations known in the literature are used: the M3Y and Migdal forces. The calculations show that Migdal interaction always results in the higher Coulomb barrier. Moreover, as $B_Z$ increases the difference between the M3Y and Migdal barrier heights systematically increases as well. As the result, the above barrier fusion cross sections calculated dynamically with the M3Y forces and surface friction are in agreement with the data. The cross sections calculated with the Migdal forces are always bel...
Energy Technology Data Exchange (ETDEWEB)
Lubian, J.; Gomes, P.R.S. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Canto, L.F. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Hussein, M.S. [Universidade de Sao Paulo (USP), SP (Brazil)
2012-07-01
Full text: In the last two decades one has asked whether the complete fusion of weakly bound systems is enhanced or suppressed when compared with the situation where there is no break process. Recent systematic results [1] based on the reduction of cross section and the comparison to the Universal Fusion Function have shown that the complete fusion cross section is indeed enhanced at sub-barrier energies and suppressed at energies above the barrier, when compared with calculations which do not take into account the couplings to breakup channels. In this contribution we discuss and propose a method to explain this conclusion. We point out the importance of direct transfer and breakup processes and also the recently observed sequential breakup that follows the transfer. Different behaviors of the dynamic polarization potentials at different energy regions are used to explain the observed fusion excitation functions for several weakly bound systems. While the breakup polarization is the main reaction channel at above the Coulomb barrier energy regime, leading to repulsive polarization, the sequential breakup (transfer followed by breakup) seems to be the main reaction mechanism at below barrier energies. This last mechanism produces attractive polarization and for this reason it enhances the complete fusion cross section. [1] L.F. Canto et al., Nucl. Phys. A 821, 51 (2009); J. of Phys. G 36, 015109 (2009). (author)
Energy Technology Data Exchange (ETDEWEB)
Santhosh, K.P., E-mail: drkpsanthosh@gmail.com; Bobby Jose, V.
2014-02-15
The total fusion cross sections for the fusion of weakly bound {sup 9}Be on {sup 27}Al and {sup 64}Zn targets at near and above the barrier have been calculated using one dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential and the calculated values are compared with experimental data. For the purpose of comparison of the fusion of weakly bound projectiles and strongly bound projectiles, the total fusion cross sections for the reaction of tightly bound nucleus {sup 16}O on {sup 64}Zn have also been computed using a similar procedure. The calculated values of total fusion cross sections in all cases are compared with coupled channel calculations using the code CCFULL. The computed cross sections using Coulomb and proximity potential explain the fusion reactions well in both cases of weakly bound and strongly bound projectiles. Reduced reaction cross sections for the systems {sup 9}Be+{sup 27}Al, {sup 9}Be+{sup 64}Zn and {sup 16}O+{sup 64}Zn have also been described.
Santhosh, K P
2013-01-01
The total fusion cross sections for the fusion of weakly bound $^{9}$Be on $^{27}$Al and $^{64}$Zn targets at near and above the barrier have been calculated using one dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential and the calculated values are compared with experimental data. For the purpose of comparison of the fusion of weakly bound projectiles and strongly bound projectiles, the total fusion cross sections for the reaction of tightly bound nucleus $^{16}$O on $^{64}$Zn have also been computed using a similar procedure. The calculated values of total fusion cross sections in all cases are compared with coupled channel calculations using the code CCFULL. The computed cross sections using Coulomb and proximity potential explain the fusion reactions well in both cases of weakly bound and strongly bound projectiles. Reduced reaction cross sections for the systems $^{9}$Be + $^{27}$Al, $^{9}$Be+ $^{64}$Zn and $^{16}$O + $^{64}$Zn have also been d...
Converse Barrier Certificate Theorem
DEFF Research Database (Denmark)
Wisniewski, Rafael; Sloth, Christoffer
2013-01-01
This paper presents a converse barrier certificate theorem for a generic dynamical system.We show that a barrier certificate exists for any safe dynamical system defined on a compact manifold. Other authors have developed a related result, by assuming that the dynamical system has no singular...... points in the considered subset of the state space. In this paper, we redefine the standard notion of safety to comply with generic dynamical systems with multiple singularities. Afterwards, we prove the converse barrier certificate theorem and illustrate the differences between ours and previous work...
Energy Technology Data Exchange (ETDEWEB)
Bhat, C.M.; /Fermilab
2011-03-01
The Recycler Ring at Fermilab uses a barrier rf systems for all of its rf manipulations. In this paper, I will give an overview of historical perspective on barrier rf system, the longitudinal beam dynamics issues, aspects of rf linearization to produce long flat bunches and methods used for emittance measurements of the beam in the RR barrier rf buckets. Current rf manipulation schemes used for antiproton beam stacking and longitudinal momentum mining of the RR beam for the Tevatron collider operation are explained along with their importance in spectacular success of the Tevatron luminosity performance.
[Vascular endothelial Barrier Function].
Ivanov, A N; Puchinyan, D M; Norkin, I A
2015-01-01
Endothelium is an important regulator of selective permeability of the vascular wall for different molecules and cells. This review summarizes current data on endothelial barrier function. Endothelial glycocalyx structure, its function and role in the molecular transport and leukocytes migration across the endothelial barrier are discussed. The mechanisms of transcellular transport of macromolecules and cell migration through endothelial cells are reviewed. Special section of this article addresses the structure and function of tight and adherens endothelial junction, as well as their importance for the regulation of paracellular transport across the endothelial barrier. Particular attention is paid to the signaling mechanism of endothelial barrier function regulation and the factors that influence on the vascular permeability.
Barriers to Effective Listening.
Hulbert, Jack E.
1989-01-01
Discusses the following barriers which interfere with listening efficiency: content, speaker, medium, distractions, mindset, language, listening speed, and feedback. Suggests ways to combat these obstacles to accurate comprehension. (MM)
The self-consistent analysis for sub-barrier fusion enhancement effect in Ca + Ca and Ni + Ni
Ma, N R; Lin, C J; Yang, L; Xu, X X; Sun, L J; Yang, F; Wu, Z D; Zhang, H Q; Liu, Z H; Wang, D X
2016-01-01
The fusion dynamic mechanism of heavy-ions at energies near the Coulomb barrier is complicated and still not very clear up to now. Accordingly, a self-consistent method based on the CCFULL calculations has been developed and applied for an ingoing study of the effect of the positive Q-value neutron transfer (PQNT) channels in this work. The typical experimental fusion data of Ca + Ca and Ni + Ni is analyzed within the unified calculation scheme. The PQNT effect in near-barrier fusion is further confirmed based on the self-consistent analysis and extracted quantitatively.
Sharma, A.; Janssen, N. M. A.; Mathijssen, S. G. J.; de Leeuw, D. M.; Kemerink, M.; Bobbert, P. A.
2011-03-01
We investigate the effect of Coulomb scattering from trapped charges on the mobility in the two-dimensional channel of an organic field-effect transistor. The number of trapped charges can be tuned by applying a prolonged gate bias. Surprisingly, after increasing the number of trapped charges to a level where strong Coulomb scattering is expected, the mobility has decreased only slightly. Simulations show that this can be explained by assuming that the trapped charges are located in the gate dielectric at a significant distance from the channel instead of in or very close to the channel. The effect of Coulomb scattering is then strongly reduced.
M.E. Rosli; B. Md Dero; A. R. Ismail; M. N. Ab Rahman
2008-01-01
Purpose: This paper explores the barriers faced by Malaysian manufacturing companies in successfullyimplementing the Supply Chain Management (SCM). The study has highlighted some pertinent factorsperforming the barriers that are most frequently reported by the studied companies. Sixteen companies, fromservice and manufacturing companies were studied over a period of two years to assess their SCM practicesthrough survey and interview processes.Design/methodology/approach: This part discusses t...
A search for parameters of universal sub-barrier fusion excitation function
Qu, W. W.; Zhang, G. L.; Wolski, R.
2016-11-01
Many fusion experimental data have been analyzed in terms of a simple universal function which could be used for predictions of fusion cross section below the barrier for arbitrary systems. Sub-barrier fusions based on the concept of Q -fusion value dependence were studied. It is attempted to parameterize the energy-reduced fusion excitation functions around the Coulomb barriers by an analytical phenomenological function. It was found that the speed of driving nuclei towards fusion is faster with the increase of mass asymmetry of colliding systems and those systems with a large difference of the ratio of neutrons to protons. However, a general trend with respect to total mass has not been observed. An exposition of more qualitative conclusions is hindered by apparent inconsistencies of measured fusion cross sections.
Wave functions of a particle with polarizability in the Coulomb potential
Kisel, V; Ovsiyuk, E; Amirfachrian, M; Red'kov, V
2011-01-01
Quantum mechanical scalar particle with polarizability is considered in the presence of the Coulomb field. Separation of variables is performed with the use of Wigner $D$-functions, the radial system of 15 equations is reduced to a single second order differential equation, which among the Coulomb term includes an additional interaction term of the form \\sigma \\alpha^{2} / M^{2}r^{4}. Various physical regimes exist that is demonstrated by examining the behavior of the curves of generalized squared radial momentum P^{2}(r). Eigenstates of the equations can be constructed in terms of double confluent Heun functions. Numerical analysis proves the existence of the bound states in the system; the lowest energy level and corresponding solution are calculated based on generalization of Ritz variational procedure.
Energy Technology Data Exchange (ETDEWEB)
Turrell, A.E., E-mail: a.turrell09@imperial.ac.uk; Sherlock, M.; Rose, S.J.
2015-10-15
Large-angle Coulomb collisions allow for the exchange of a significant proportion of the energy of a particle in a single collision, but are not included in models of plasmas based on fluids, the Vlasov–Fokker–Planck equation, or currently available plasma Monte Carlo techniques. Their unique effects include the creation of fast ‘knock-on’ ions, which may be more likely to undergo certain reactions, and distortions to ion distribution functions relative to what is predicted by small-angle collision only theories. We present a computational method which uses Monte Carlo techniques to include the effects of large-angle Coulomb collisions in plasmas and which self-consistently evolves distribution functions according to the creation of knock-on ions of any generation. The method is used to demonstrate ion distribution function distortions in an inertial confinement fusion (ICF) relevant scenario of the slowing of fusion products.
Ultranarrow resonance in Coulomb drag between quantum wires at coinciding densities
Dmitriev, A. P.; Gornyi, I. V.; Polyakov, D. G.
2016-08-01
We investigate the influence of the chemical potential mismatch Δ (different electron densities) on Coulomb drag between two parallel ballistic quantum wires. For pair collisions, the drag resistivity ρD(Δ ) shows a peculiar anomaly at Δ =0 with ρD being finite at Δ =0 and vanishing at any nonzero Δ . The "bodyless" resonance in ρD(Δ ) at zero Δ is only broadened by processes of multiparticle scattering. We analyze Coulomb drag for finite Δ in the presence of both two- and three-particle scattering within the kinetic equation framework, focusing on a Fokker-Planck picture of the interaction-induced diffusion in momentum space of the double-wire system. We describe the dependence of ρD on Δ for both weak and strong intrawire equilibration due to three-particle scattering.
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.
Classification of N=2 Superconformal Field Theories with Two-Dimensional Coulomb Branches, II
Argyres, P C; Argyres, Philip C.; Wittig, John R.
2005-01-01
We continue the classification of 2-dimensional scale-invariant rigid special Kahler (RSK) geometries. This classification was begun in [hep-th/0504070] where singularities corresponding to curves of the form y^2=x^6 with a fixed canonical basis of holomorphic one forms were analyzed. Here we perform the analysis for the y^2=x^5 type singularities. (The final maximal singularity type, y^2=x^3(x-1)^3, will be analyzed in a later paper.) These singularities potentially describe the Coulomb branches of N=2 supersymmetric field theories in four dimensions. We show that there are only 13 solutions satisfying the integrability condition (enforcing the RSK geometry of the Coulomb branch) and the Z-consistency condition (requiring massless charged states at singularities). Of these solutions, one has a marginal deformation, and corresponds to the known solution for certain Sp(2) gauge theories, while the rest correspond to isolated strongly interacting conformal field theories.
Classification of N=2 Superconformal Field Theories with Two-Dimensional Coulomb Branches
Argyres, P C; Shapere, A D; Wittig, J R; Argyres, Philip C.; Crescimanno, Michael; Shapere, Alfred D.; Wittig, John R.
2005-01-01
We study the classification of 2-dimensional scale-invariant rigid special Kahler (RSK) geometries, which potentially describe the Coulomb branches of N=2 supersymmetric field theories in four dimensions. We show that this classification is equivalent to the solution of a set of polynomial equations by using an integrability condition for the central charge, scale invariance, constraints coming from demanding single-valuedness of physical quantities on the Coulomb branch, and properties of massless BPS states at singularities. We find solutions corresponding to lagrangian scale invariant theories--including the scale invariant G_2 theory not found before in the literature--as well as many new isolated solutions (having no marginal deformations). All our scale-invariant RSK geometries are consistent with an interpretation as effective theories of N=2 superconformal field theories, and, where we can check, turn out to exist as quantum field theories.
The impact of sharp screening on the Coulomb scattering problem in three dimensions
Yakovlev, S L; Yarevsky, E; Elander, N
2010-01-01
The scattering problem for two particles interacting via the Coulomb potential is examined for the case where the potential has a sharp cut-off at some distance. The problem is solved for two complimentary situations, firstly when the interior part of the Coulomb potential is left in the Hamiltonian and, secondly, when the long range tail is considered as the potential. The partial wave results are summed up to obtain the wave function in three dimensions. It is shown that in the domains where the wave function is expected to be proportional to the known solutions, the proportionality is given by an operator acting on the angular part of the wave function. The explicit representation for this operator is obtained in the basis of Legendre polynomials. We proposed a driven Schr\\"odinger equation including an inhomogeneous term of the finite range with purely outgoing asymptotics for its solution in the case of the three dimensional scattering problem with long range potentials.
Phase Diagram, Correlation Gap, and Critical Properties of the Coulomb Glass
Goethe, Martin; Palassini, Matteo
2009-07-01
We investigate the lattice Coulomb glass model in three dimensions via Monte Carlo simulations. No evidence for an equilibrium glass phase is found down to very low temperatures, although the correlation length increases rapidly near T=0. A charge-ordered phase exists at low disorder. The transition to this phase is consistent with the random field Ising universality class, which shows that the interaction is effectively screened at moderate temperature. For large disorder, the single-particle density of states near the Coulomb gap satisfies the scaling relation g(γ,T)=Tδf(|γ|/T) with δ=2.01±0.05 in agreement with the prediction of Efros and Shklovskii. For decreasing disorder, a crossover to a larger effective exponent occurs due to the proximity of the charge-ordered phase.
Casal, J; Arias, J M; Gómez-Camacho, J
2016-01-01
A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly-bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of $B(E1)$ distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to $^{11}$Li ($^{9}$Li+n+n) and $^6$He ($^{4}$He+n+n) three-body systems for which some data exist.
Casal, J.; Rodríguez-Gallardo, M.; Arias, J. M.; Gómez-Camacho, J.
2016-04-01
A relationship between the Coulomb inclusive break-up probability and the radiative capture reaction rate for weakly bound three-body systems is established. This direct link provides a robust procedure to estimate the reaction rate for nuclei of astrophysical interest by measuring inclusive break-up processes at different energies and angles. This might be an advantageous alternative to the determination of reaction rates from the measurement of B (E 1 ) distributions through exclusive Coulomb break-up experiments. In addition, it provides a reference to assess the validity of different theoretical approaches that have been used to calculate reaction rates. The procedure is applied to 11Li (9Li+n +n ) and 6He (4He+n +n ) three-body systems for which some data exist.
Nemati Aram, Tahereh; Asgari, Asghar; Mayou, Didier
2016-07-01
Bulk heterojunction (BHJ) organic photovoltaic cells are analysed within a simple efficient model that includes the important physical properties of such photovoltaic systems. In this model, in contrast with most of the previous studies, we take into account the motion of both the electron and the hole in the separation process at the donor-acceptor interface. We theoretically examine the exciton dissociation yield under the influences of charge Coulomb interaction and non-radiative recombination. We find that the electron-hole local Coulomb attraction and charge carriers' coupling parameters play an important role in the system performance and in the optimal energy conversion efficiency of the BHJ photocell. We show that the fixed-hole models tend to underestimate the yield.
Coulomb explosion imaging of bromobenzene and bromophenol molecules following Br K-shell ionization
Energy Technology Data Exchange (ETDEWEB)
Iwayama, H; Nagaya, K; Murakami, H; Ohmasa, Y; Yao, M, E-mail: yao@scphys.kyoto-u.ac.j [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan)
2010-09-28
We have performed multiple-ion coincidence momentum imaging measurements for bromobenzene and bromophenol molecules irradiated by hard x-ray photons at Br K-shell edge. Dominant fragment ions were singly charged monatomic ions H{sup +}, C{sup +}, O{sup +} and Br{sup +}. This indicates that parent molecules became highly charged through Auger cascade of Br core shell ionization. From an analysis of momentum vectors of ions, we found that the ejection directions of fragment ions strongly reflected the molecular structure of the neutral state. We can reproduce experimental results well by the trajectory analysis of fragment ions based on a Coulomb explosion model. This result shows that hard x-ray radiation enables us to apply Coulomb explosion imaging even for complex molecules such as benzene molecules.
Ergun, A; Buyukcizmeci, N; Ogul, R; Botvina, A S
2014-01-01
Theoretical calculations are performed to investigate the angular momentum and Coulomb effects on fragmentation and multifragmentation in peripheral heavy-ion collisions at Fermi energies. Inhomogeneous distributions of hot fragments in the freeze-out volume are taken into account by microcanonical Markov chain calculations within the Statistical Multifragmentation Model (SMM). Including an angular momentum and a long-range Coulomb interaction between projectile and target residues leads to new features in the statistical fragmentation picture. In this case, one can obtain specific correlations of sizes of emitted fragments with their velocities and an emission in the reaction plane. In addition, one may see a significant influence of these effects on the isotope production both in the midrapidity and in the kinematic regions of the projectile/target. The relation of this approach to the simulations of such collisions with dynamical models is also discussed.
Probing core polarization around 78Ni: intermediate energy Coulomb excitation of 74Ni
Directory of Open Access Journals (Sweden)
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.
First measurement with a new setup for low-energy Coulomb excitation studies at INFN LNL
Rocchini, M.; Hadyńska-Klȩk, K.; Nannini, A.; Valiente-Dobón, J. J.; Goasduff, A.; Testov, D.; John, P. R.; Mengoni, D.; Zielińska, M.; Bazzacco, D.; Benzoni, G.; Boso, A.; Cocconi, P.; Chiari, M.; Doherty, D. T.; Galtarossa, F.; Jaworski, G.; Komorowska, M.; Matejska-Minda, M.; Melon, B.; Menegazzo, R.; Napiorkowski, P.; Napoli, D. R.; Ottanelli, M.; Perego, A.; Ramina, L.; Rampazzo, M.; Recchia, F.; Riccetto, S.; Rosso, D.; Siciliano, M.; Sona, P.
2017-07-01
A new segmented particle detector, SPIDER, has been designed to be used as an ancillary device with the GALILEO γ-ray spectrometer, as well as with other multi-detector γ-ray arrays that will be available at LNL in the future (e.g. AGATA). To commission the SPIDER-GALILEO experimental setup, a multi-step Coulomb excitation experiment was carried out with a 240 MeV beam of 66Zn produced by the Tandem-XTU accelerator at INFN Laboratori Nazionali di Legnaro. The measured particle and γ-ray spectra are compared with the results of detailed GEANT4 simulations which used the Coulomb excitation cross sections, estimated with the computer code GOSIA, as an input. The preliminary results indicate that precise transition probabilities will be obtained which are essential for solving discrepancies reported in the literature for this nucleus.
Modified Poisson-Nernst-Planck model with accurate Coulomb correlation in variable media
Liu, Pei; Xu, Zhenli
2016-01-01
We derive a set of modified Poisson-Nernst-Planck (PNP) equations for ion transport from the variation of the free energy functional which includes the many-body Coulomb correlation in media of variable dielectric coefficient. The correlation effects are considered through the Debye charging process in which the self energy of an ion is governed by the generalized Debye-H\\"uckel equation. We develop the asymptotic expansions of the self energy taking the ion radius as the small parameter such that the multiscale model can be solved efficiently by numerical methods. We show that the variations of the energy functional give the self-energy-modified PNP equations which satisfy a proper energy law. We present the numerical results from different asymptotic expansions with a semi-implicit conservative numerical method and investigate the effect of the Coulomb correlation.
Communication: Three-fold covariance imaging of laser-induced Coulomb explosions
Pickering, James D.; Amini, Kasra; Brouard, Mark; Burt, Michael; Bush, Ian J.; Christensen, Lauge; Lauer, Alexandra; Nielsen, Jens H.; Slater, Craig S.; Stapelfeldt, Henrik
2016-04-01
We apply a three-fold covariance imaging method to analyse previously acquired data [C. S. Slater et al., Phys. Rev. A 89, 011401(R) (2014)] on the femtosecond laser-induced Coulomb explosion of spatially pre-aligned 3,5-dibromo-3',5'-difluoro-4'-cyanobiphenyl molecules. The data were acquired using the "Pixel Imaging Mass Spectrometry" camera. We show how three-fold covariance imaging of ionic photofragment recoil trajectories can be used to provide new information about the parent ion's molecular structure prior to its Coulomb explosion. In particular, we show how the analysis may be used to obtain information about molecular conformation and provide an alternative route for enantiomer determination.
Exact solution to the Coulomb wave using the linearized phase-amplitude method
Directory of Open Access Journals (Sweden)
Shuji Kiyokawa
2015-08-01
Full Text Available The author shows that the amplitude equation from the phase-amplitude method of calculating continuum wave functions can be linearized into a 3rd-order differential equation. Using this linearized equation, in the case of the Coulomb potential, the author also shows that the amplitude function has an analytically exact solution represented by means of an irregular confluent hypergeometric function. Furthermore, it is shown that the exact solution for the Coulomb potential reproduces the wave function for free space expressed by the spherical Bessel function. The amplitude equation for the large component of the Dirac spinor is also shown to be the linearized 3rd-order differential equation.
Nakajima, Hiraku
2015-01-01
Consider the $3$-dimensional $\\mathcal N=4$ supersymmetric gauge theory associated with a compact Lie group $G$ and its quaternionic representation $\\mathbf M$. Physicists study its Coulomb branch, which is a noncompact hyper-K\\"ahler manifold, such as instanton moduli spaces on $\\mathbb R^4$, $SU(2)$-monopole moduli spaces on $\\mathbb R^3$, etc. In this paper and its sequel, we propose a mathematical definition of the coordinate ring of the Coulomb branch, using the vanishing cycle cohomology group of a certain moduli space for a gauged $\\sigma$-model on the $2$-sphere associated with $(G,\\mathbf M)$. In this first part, we check that the cohomology group has the correct graded dimensions expected from the monopole formula proposed by Cremonesi, Hanany and Zaffaroni arXiv:1309.2657. A ring structure (on the cohomology of a modified moduli space) will be introduced in the sequel of this paper.
On the theory and simulation of multiple Coulomb scattering of heavy-charged particles.
Striganov, S I
2005-01-01
The Moliere theory of multiple Coulomb scattering is modified to take into account the difference between processes of scattering off atomic nuclei and electrons. A simple analytical expression for angular distribution of charged particles passing through a thick absorber is found. It does not assume any special form for a differential scattering cross section and has a wider range of applicability than a gaussian approximation. A well-known method to simulate multiple Coulomb scatterings is based on treating 'soft' and 'hard' collisions differently. An angular deflection in a large number of 'soft' collisions is sampled using the proposed distribution function, a small number of 'hard' collision are simulated directly. A boundary between 'hard' and 'soft' collisions is defined, providing a precise sampling of a scattering angle (1% level) and a small number of 'hard' collisions. A corresponding simulating module takes into account projectile and nucleus charged distributions and exact kinematics of a projectile-electron interaction.
On the Theory and Simulation of Multiple Coulomb Scattering of Heavy Charged Particles
Striganov, S I
2004-01-01
The Moliere theory of multiple Coulomb scattering is modified to take into account difference between scattering off atomic nuclei and electron. A simple analytical expression for angular distribution of charged particles passing through a thick absorber is found. It does not assume any special form for a differential cross section and has wider range of applicability than a Gaussian approximation. A well-known method to simulate multiple Coulomb scattering is based on the different treatment of soft and hard collisions. An angular deflection in a large number of soft collisions is sampled using the proposed distribution function, a small number of hard collisions are simulated directly. A boundary between hard and soft collisions is defined providing a precise sampling of scattering angle (1% level) and small number of hard collisions. A corresponding simulation module takes into account projectile and nucleus charge distributions and exact kinematics of a projectile-electron interaction.
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.
Application of the complex scaling method in solving three-body Coulomb scattering problem
Lazauskas, R.
2017-03-01
The three-body scattering problem in Coulombic systems is a widespread, yet unresolved problem using the mathematically rigorous methods. In this work this long-term challenge has been undertaken by combining distorted waves and Faddeev–Merkuriev equation formalisms in conjunction with the complex scaling technique to overcome the difficulties related with the boundary conditions. Unlike the common belief, it is demonstrated that the smooth complex scaling method can be applied to solve the three-body Coulomb scattering problem in a wide energy region, including the fully elastic domain and extending to the energies well beyond the atom ionization threshold. A newly developed method is used to study electron scattering on the ground states of hydrogen and positronium atoms as well as a {e}++{{H}}({n}=1)\\rightleftarrows {{p}}+{Ps}({n}=1) reaction. Where available, obtained results are compared with the experimental data and theoretical predictions, proving the accuracy and efficiency of the newly developed method.
Coulomb displacement energies as a probe for nucleon pairing in the f7/2 shell
Kankainen, A.; Eronen, T.; Gorelov, D.; Hakala, J.; Jokinen, A.; Kolhinen, V. S.; Reponen, M.; Rissanen, J.; Saastamoinen, A.; Sonnenschein, V.; ńystö, J.
2014-05-01
Coulomb displacement energies of T =1/2 mirror nuclei have been studied via a series of high-precision QEC-value measurements with the double Penning trap mass spectrometer JYFLTRAP. Most recently, the QEC values of the f7/2-shell mirror nuclei V45 (QEC=7123.82(22) keV) and Mn49 (QEC=7712.42(24) keV) have been measured with unprecedented precision. The data reveal a 16-keV (1.6σ) offset in the adopted Atomic Mass Evaluation 2012 value of Mn49, suggesting the need for further measurements to verify whether there is a breakdown of the quadratic form of the isobaric multiplet mass equation in the fp shell. Precisely measured QEC values confirm that the pairing effect in the Coulomb energies is quenched when entering the f7/2 shell and reaches a minimum in the midshell.
Asymptotic regimes for diffractive scatterings at ultrahigh energies and coulomb interaction
Anisovich, V V; Nyiri, J
2016-01-01
Comparative analysis of the interplay of hadron and Coulomb interactions in $pp^\\pm$ scattering amplitudes is performed for two extreme cases: for the asymptotic interaction of hadrons in black disk and resonant disk modes. The interactions are discussed in terms of the $K$-matrix function technique, the interference effects are estimated in the energy interval $\\sqrt{s}=1-10^6$ TeV. In both cases the real part of the hadronic amplitude is concentrated on the boundary of the disks in the impact parameter space that causes a growth of interference effects with the energy increase. For the $pp$ scattering at $\\sqrt{s}\\sim 10$ TeV an interplay of the hadron and Coulomb interactions in the resonant disk modes is realized in a specific shoulder in $d\\sigma_{el}/d{\\bf q}^2$ at ${\\bf q}^2\\sim 0.0025-0.0075$ GeV$^2$.
Song, Xiaohong; Sheng, Zhihao; Liu, Peng; Chen, Zhangjin; Yang, Weifeng; Hu, Shilin; Lin, C D; Chen, Jing
2016-01-01
Strong field photoelectron holography has been proposed as a means for interrogating the spatial and temporal information of electrons and ions in a dynamic system. After ionization, part of the electron wave packet may directly go to the detector (the reference wave), while another part may be driven back to the ion where it scatters off (the signal wave). The interference hologram of the two waves may be used to retrieve the target information. However, unlike conventional optical holography, the propagations of electron wave packets are affected by the Coulomb potential as well as by the laser field. In addition, electrons are emitted over the whole laser pulse duration, thus multiple interferences may occur. In this work, we used a generalized quantum-trajectory Monte Carlo method to investigate the effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram. We showed that photoelectron hologram can be well described only when the nonadiabatic effect in ionization i...
Institute of Scientific and Technical Information of China (English)
NIU Dongmei; LI Haiyang; LIANG Feng; WEN Lihua; LUO Xiaolin
2005-01-01
The Coulomb explosion of ammonia clusters induced by nanosecond laser at 532 nm with an intensity of ~1012 Wcm-2 has been studied by time of flight mass spectrometry. The dominant multiply charged ions are N3+ and N2+ with kinetic energies of 110 and 50 eV respectively. The electrons generated from the multiphoton ionization are heated through inverse bremsstrahlung by the laser field when colliding with neutral or ionic particles. When their energies surpass the corresponding ionization potentials of the molecules or ions, the subsequent electron impact ionization may take place thus resulting in multi-charged nitrogen ions. Covariance analysis is made to study the possible pathways of the Coulomb explosion.
Eikonal analysis of Coulomb distortion in quasi-elastic electron scattering
Tjon, J A
2008-01-01
An eikonal expansion is used to provide systematic corrections to the eikonal approximation through order $1/k^2$, where $k$ is the wave number. Electron wave functions are obtained for the Dirac equation with a Coulomb potential. They are used to investigate distorted-wave matrix elements for quasi-elastic electron scattering from a nucleus. A form of effective-momentum approximation is obtained using trajectory-dependent eikonal phases and focusing factors. Fixing the Coulomb distortion effects at the center of the nucleus, the often-used ema approximation is recovered. Comparisons of these approximations are made with full calculations using the electron eikonal wave functions. The ema results are found to agree well with the full calculations.
Song, Xiaohong; Lin, Cheng; Sheng, Zhihao; Yu, Xianhuan; Yang, Weifeng; Hu, Shilin; Chen, Jing; Xu, SongPo; Chen, YongJu; Quan, Wei; Liu, XiaoJun
2016-01-01
A novel and universal interference structure is found in the photoelectron momentum distribution of atoms in intense infrared laser field. Theoretical analysis shows that this structure can be attributed to a new form of Coulomb-field-driven backward-scattering of photoelectrons in the direction perpendicular to the laser field, in contrast to the conventional rescattering along the laser polarization direction. This transverse backward-scattering process is closely related to a family of photoelectrons initially ionized within a time interval of less than 200 attosecond around the crest of the laser electric field. Those electrons, acquiring near-zero return energy in the laser field, will be pulled back solely by the ionic Coulomb field and backscattered in the transverse direction. Moreover, this rescattering process mainly occurs at the first or the second return times, giving rise to different phases of the photoelectrons. The interference between these photoelectrons leads to unique curved interference ...