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Sample records for charge exchange reactions

  1. Multistep processes in charge-exchange reactions

    CERN Document Server

    Demetriou, P; Marianski, B

    2002-01-01

    Cross sections for the charge-exchange sup 6 sup 5 Cu(p, n) sup 6 sup 5 Zn reaction at the incident energy of 27 MeV and the sup 1 sup 0 sup 0 Mo(p, n) sup 1 sup 0 sup 0 Tc reaction at the incident energy of 26 MeV have been calculated using the multistep direct reaction theory of Feshbach, Kerman and Koonin. The theory was modified to include the non-DWBA matrix elements and the isovector collective vibrations according to the prescription of Marcinkowski and Marianski. The results show enhanced contributions from two-, three- and four-step direct reactions in agreement with experiment.

  2. Charge exchange and chemical reactions with trapped Th3+

    International Nuclear Information System (INIS)

    We have measured the reaction rates of trapped, buffer gas cooled Th3+ and various gases and have analyzed the reaction products using trapped ion mass spectrometry techniques. Ion trap lifetimes are usually limited by reactions with background molecules, and the high electron affinity of multiply charged ions such as Th3+ make them more prone to loss. Our results show that reactions of Th3+ with carbon dioxide, methane, and oxygen all occur near the classical Langevin rate, while reaction rates with argon, hydrogen, and nitrogen are orders of magnitude lower. Reactions of Th3+ with oxygen and methane proceed primarily via charge exchange, while simultaneous charge exchange and chemical reaction occurs between Th3+ and carbon dioxide. Loss rates of Th3+ in helium are consistent with reaction with impurities in the gas. Reaction rates of Th3+ with nitrogen and argon depend on the internal electronic configuration of the Th3+.

  3. Charge Exchange and Chemical Reactions with Trapped Th$^{3+}$

    CERN Document Server

    Churchill, L R; Chapman, M S

    2010-01-01

    We have measured the reaction rates of trapped, buffer gas cooled Th$^{3+}$ and various gases and have analyzed the reaction products using trapped ion mass spectrometry techniques. Ion trap lifetimes are usually limited by reactions with background molecules, and the high electron affinity of multiply charged ions such as Th$^{3+}$ make them more prone to loss. Our results show that reactions of Th$^{3+}$ with carbon dioxide, methane, and oxygen all occur near the classical Langevin rate, while reaction rates with argon, hydrogen, and nitrogen are orders of magnitude lower. Reactions of Th$^{3+}$ with oxygen and methane proceed primarily via charge exchange, while simultaneous charge exchange and chemical reaction occurs between Th$^{3+}$ and carbon dioxide. Loss rates of Th$^{3+}$ in helium are consistent with reaction with impurities in the gas. Reaction rates of Th$^{3+}$ with nitrogen and argon depend on the internal electronic configuration of the Th$^{3+}$.

  4. Study of nuclei' excitation in the charge exchange reactions (Draft)

    International Nuclear Information System (INIS)

    Carried out experimental and theoretical studies show, that in the nuclear charge exchange reactions there is an unique ability for study both properties and behavior of the delta-isobar in the excited nuclear environment. However for theoretical analysis of these reactions it is necessary have experimental data on nuclei charge exchange on free nucleons. It is offered the experiment of measurement dependence of inclusive cross section of the tritium nuclei charge exchange in 3He nuclei on hydrogen from transferred energy. This reaction is isotopically dependent on 3He nuclei in tritons charge exchange reaction on neutrons. Aim of proposed experiment is checking of a hypothesis believability about the delta-isobar excitation in flying nucleus, and measurement of the process intensity. Peculiarity of this experiment is application of relativistic tritons beams formed from accelerated fragments of 4He nuclei. Experimental facility presents of combination of two one-arm spectrometers: first one - time-flying spectrometer for measurement tritium nuclei impulse in beam to target with accuracy 0.3 % for 6 GeV/s and identification of tritium nuclei, the second one - magnetic spectrometer for identification and measurement of 3He nuclei impulse forming in the result of the charge exchange reaction

  5. Microscopic optical potentials - study of charge-exchange reactions

    International Nuclear Information System (INIS)

    The present thesis is engaged in two different aspects of direct nuclear reactions, namely on the one hand in the microscopic calculation of the imaginary optical potential for the elastic alpha-nucleus scattering as well on the other hand in the microscopic analysis of giant resonance states which are excited by (p,n) and (n,p) charge-exchange reactions. In the first part in the framework of the nuclear structure approximation to the optical potential a microscopic calculation of the imaginary part of the optical potential for α40Ca scattering at Esub(α) = 31 and 100 MeV is performed. In the second part the 208Pb(p,n) and 208Pb(n,p) charge-exchange reactions are studied at low ( E 100 MeV) incident energies. (orig./HS)

  6. Pion charge-exchange reactions: The analog state transitions

    International Nuclear Information System (INIS)

    The general features of pion charge-exchange reactions leading to nuclear-isobaric-analog states (IAS) and double-isobaric-analog states (DIAS), as they have emerged from studies over the past ten years, are reviewed. The energy range investigated is 20 to 550 MeV for IAS transitions and 20 to 300 MeV for DIAS transitions. These data are seen to play an important role in characterizing the pion optical potential, in determining the Δ-N interaction in nuclei, and in the study of nucleon correlations in nuclei. Recent progress achieved in understanding the role of such correlations in double-charge-exchange reactions is reviewed. 55 refs., 43 figs., 3 tabs

  7. Elastic scattering and charge exchange reactions with exotic beams

    International Nuclear Information System (INIS)

    The elastic scattering of 6He, 10,11Be secondary beams on a (CH2)3 target and the charge exchange reaction p(6He,6Li)n have been measured. Very good agreement was found for the 6He+12C data with a four-body eikonal scattering model. A microscopic optical potential was used to reproduce the proton-nucleus elastic scattering data. (author)

  8. Nucleon charge-exchange reactions at intermediate energy

    Energy Technology Data Exchange (ETDEWEB)

    Alford, W.P. [Western Ontario Univ., London, ON (Canada). Dept. of Physics]|[TRIUMF, Vancouver, BC (Canada); Spicer, B.M. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1997-12-31

    An historical review of the development of ideas pertaining to Gamow-Teller giant resonances is given, and a description of the emergence of techniques for the study of charge exchange reactions - particularly the technical advances which yielded the recent volume of new date. The present status of charge exchange reactions is reviewed and assessed. Evidence is presented from the {sup 14}C(p,n) reaction for the dominance of the spin-isospin component of the nucleon-nucleon interaction in intermediate energy reactions. In (p,n) reactions the Gamow-Teller giant resonance dominates the spectra, with higher multipoles contributing. By contrast, in (n,p) reactions in the heavier nuclei, the Gamow-Teller transitions are substantially Pauli-blocked and the spin dipole resonance dominates, with contributions from higher multipoles. Discussions of the multipole decomposition process, used to obtain from the data the contributions of the different multipoles, and the contributions of the multipoles, are given. 226 refs., 19 figs.

  9. Delta excitation in nuclei: the lesson of charge exchange reactions

    International Nuclear Information System (INIS)

    We present an attempt of theoretical interpretation of charge exchange reactions on nuclei in the region of the delta resonance. Special care is taken to insure consistency with the constraints from pion and photon excitation channels. Good agreement with measured spectra can be obtained for all types of targets and incident ions except for polarized deuterons data which appear hardly reconcilable with the others within our interpretation. Despite the peripheral character of these reactions, a sizeable part of the observed downward shift of the resonance is possibly ascribable to a yet undetected collective mode of the nucleus at high excitation, the pionic branch. Our limited commitment is due to uncomplete knowledge of the NN → N Δ interaction and the transition form factors of the probing ions which has been palliated by some phenomenology

  10. Coherent pion production in heavy ion charge exchange reactions

    International Nuclear Information System (INIS)

    We report the first observation of coherent pion production induced by a heavy ion charge exchange reaction. The (12C,12N) reaction [D. Bachelier et al., Phys. Lett. B 172 (1986) 23; M. Roy-Stephan et al., Nucl. Phys. A 488 (1988) 178] at 1.1 GeV/nucleon has been used to shine negative (off-shell) pions on nuclei and observe (on-shell) pions, leaving the target nucleus in its ground state. The experiment was performed at the Laboratoire National Saturne with the SPES4-π setup [Laurent Farhi PHD thesis IPNO-T97-12, Universite d'Orsay, 1997; Rasmus Dahl Ph.D., Niels Bohr Institutet, Copenhagen (1999)

  11. Deuteron-proton charge exchange reaction at small transfer momentum

    CERN Document Server

    Ladygina, N B

    2004-01-01

    The charge-exchange reaction pd -> npp at 1 GeV projectile proton energy is studied. This reaction is considered in a special kinematics, when the transfer momentum from the beam proton to fast outgoing neutron is close to zero. Our approach is based on the Alt-Grassberger-Sandhas formulation of the multiple-scattering theory for the three-nucleon system. The matrix inversion method has been applied to take account of the final state interaction (FSI) contributions. The differential cross section, tensor analyzing power $C_{0,yy}$, vector-vector $C_{y,y}$ and vector-tensor $C_{y,xz}$ spin correlation parameters of the initial particles are presented. It is shown, that the FSI effects play a very important role under such kinematical conditions. The high sensitivity of the considered observables to the elementary nucleon-nucleon amplitudes has been obtained.

  12. Neutrino and antineutrino charge-exchange reactions on 12C

    International Nuclear Information System (INIS)

    We extend the formalism of weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture. Explicit violation of the conserved vector current hypothesis by the Coulomb field, as well as development of a sum-rule approach for inclusive cross sections, has been worked out. We have done a thorough study of exclusive (ground-state) properties of 12B and 12N within the projected quasiparticle random phase approximation (PQRPA). Good agreement with experimental data achieved in this way put into evidence the limitations of the standard RPA and QRPA models, which come from the inability of the RPA to open the p3/2 shell and from the nonconservation of the number of particles in the QRPA. The inclusive neutrino/antineutrino (ν/ν-tilde) reactions 12C(ν,e-)12N and 12C(ν-tilde,e+)12B are calculated within both the PQRPA and the relativistic QRPA. It is found that (i) the magnitudes of the resulting cross sections are close to the sum-rule limit at low energy, but significantly smaller than this limit at high energies, for both ν and ν-tilde; (ii) they increase steadily when the size of the configuration space is augmented, particularly for ν/ν-tilde energies >200 MeV; and (iii) they converge for sufficiently large configuration space and final-state spin. The quasi-elastic 12C(ν,μ-)12N cross section recently measured in the MiniBooNE experiment is briefly discussed. We study the decomposition of the inclusive cross section based on the degree of forbiddenness of different multipoles. A few words are dedicated to the ν/ν-tilde-12C charge-exchange reactions related to astrophysical applications.

  13. Charge-exchange reaction by Reggeon exchange and W{sup +}W{sup −}-fusion

    Energy Technology Data Exchange (ETDEWEB)

    Schicker, R. [Phys. Inst., University Heidelberg (Germany)

    2015-04-10

    Charge-exchange reactions at high energies are examined. The existing cross section data on the Reggeon induced reaction pp → n + Δ{sup ++} taken at the ZGS and ISR accelerators are extrapolated to the energies of the RHIC and LHC colliders. The interest in the charge-exchange reaction induced by W{sup ±}-fusion is presented, and the corresponding QCD-background is examined.

  14. Charge-exchange and charge-conserving reactions on Mg, Ar, Zr, and Sn isotopes

    International Nuclear Information System (INIS)

    We investigate charge-exchange reactions (CEXRs) and charge-conserving reactions (CCORs) on Mg, Ar, Zr, and Sn isotopes by comparing our theoretical results to relevant experimental data on stable nuclei. As for CEXRs, first, we discuss nuclear beta decay because it may give more convincing input data on the network calculations for successive capture reactions by protons and neutrons. Second, we address the importance of the Gamow Teller (GT) states that are low-lying excited states well known in the conventional nuclear physics while high-lying excited states still remain to be studied. The third topic, which is viable through the CCORs, is the symmetry energy associated with the equation of state of nuclear matter. By using the CCORs, we can study the isoscalar giant dipole resonance (ISGDR) and the pigmy dipole resonance (PDR). We discuss theoretical results regarding these CEXRs and CCORs on 26Mg, 40Ar, 90,92Zr, and 112∼124Sn and compare them with available experimental data. Our calculations are carried out by using the proton-neutron quasi-particle random phase approximation (pnQRPA), the QRPA, the deformed QRPA (DQRPA), the shell model and a hybrid model. Our results are shown to agree with the data available. These nuclear reactions considered in this report will complement capture reactions by protons and neutrons which are of vital importance for understanding the element abundances in the cosmos.

  15. New charge exchange model of GEANT4 for 9Be(p,n)9B reaction

    International Nuclear Information System (INIS)

    A new data-based charge exchange model of GEANT4 dedicated to the 9Be(p,n)9B reaction is developed by taking the ENDF/B-VII.1 differential cross-section data as input. Our model yields results that are in good agreement with the experimental neutron yield spectrum data obtained for proton beams of energy (20–35) MeV. In particular, in contrast to all the considered GEANT4 hadronic models, the peak structure resulting from the discrete neutrons generated by the charge-exchange reaction is observed to be accurately reproduced in our model

  16. Core polarization phenomena in pion-nucleus charge-exchange reactions above the delta resonance

    International Nuclear Information System (INIS)

    We study pion-induced single- and double-charge exchange reactions in nuclei at energies above the Δ(3/2,3/2) resonance using a microscopic, parameter-free Glauber approach. We introduce corrections in the amplitudes due to the medium polarization from an isospin-flip spin-nonflip source which dominates the reaction in the transitions studied and which has not previously been identified. Using an effective force derived from the study of electromagnetic transitions we obtain sizable reductions of the cross sections in both single- and double-charge exchanges, which bring the results of both reactions into close agreement with experiment. Predictions for angular distributions for both reactions on 14C, 18O, and 42Ca targets are made which should serve as guidelines for experiments planned in this region and as further tests of the proposed isovector renormalization

  17. What can we learn from A(π+, η)B charge exchange reaction?

    International Nuclear Information System (INIS)

    Within DWIA formalism, the η production cross sections from nuclear target by charge exchange reaction A(π+, η)B are calculated. For 13C target the cross sections at forward angles are of the order of 10 μb/sr at Tπ = 660 MeV, which can be measured experimentally. The high momentum component of the wave function of single particle bound state is essential for describing this reaction

  18. Charge Exchange Reaction in Dopant-Assisted Atmospheric Pressure Chemical Ionization and Atmospheric Pressure Photoionization

    Science.gov (United States)

    Vaikkinen, Anu; Kauppila, Tiina J.; Kostiainen, Risto

    2016-04-01

    The efficiencies of charge exchange reaction in dopant-assisted atmospheric pressure chemical ionization (DA-APCI) and dopant-assisted atmospheric pressure photoionization (DA-APPI) mass spectrometry (MS) were compared by flow injection analysis. Fourteen individual compounds and a commercial mixture of 16 polycyclic aromatic hydrocarbons were chosen as model analytes to cover a wide range of polarities, gas-phase ionization energies, and proton affinities. Chlorobenzene was used as the dopant, and methanol/water (80/20) as the solvent. In both techniques, analytes formed the same ions (radical cations, protonated molecules, and/or fragments). However, in DA-APCI, the relative efficiency of charge exchange versus proton transfer was lower than in DA-APPI. This is suggested to be because in DA-APCI both dopant and solvent clusters can be ionized, and the formed reagent ions can react with the analytes via competing charge exchange and proton transfer reactions. In DA-APPI, on the other hand, the main reagents are dopant-derived radical cations, which favor ionization of analytes via charge exchange. The efficiency of charge exchange in both DA-APPI and DA-APCI was shown to depend heavily on the solvent flow rate, with best efficiency seen at lowest flow rates studied (0.05 and 0.1 mL/min). Both DA-APCI and DA-APPI showed the radical cation of chlorobenzene at 0.05-0.1 mL/min flow rate, but at increasing flow rate, the abundance of chlorobenzene M+. decreased and reagent ion populations deriving from different gas-phase chemistry were recorded. The formation of these reagent ions explains the decreasing ionization efficiency and the differences in charge exchange between the techniques.

  19. Electron capture rates in stars studied with heavy ion charge exchange reactions

    CERN Document Server

    Bertulani, C A

    2015-01-01

    Indirect methods using nucleus-nucleus reactions at high energies (here, high energies mean $\\sim$ 50 MeV/nucleon and higher) are now routinely used to extract information of interest for nuclear astrophysics. This is of extreme relevance as many of the nuclei involved in stellar evolution are short-lived. Therefore, indirect methods became the focus of recent studies carried out in major nuclear physics facilities. Among such methods, heavy ion charge exchange is thought to be a useful tool to infer Gamow-Teller matrix elements needed to describe electron capture rates in stars and also double beta-decay experiments. In this short review, I provide a theoretical guidance based on a simple reaction model for charge exchange reactions.

  20. Neutrino nuclear responses for double beta decays and astro neutrinos by charge exchange reactions

    Science.gov (United States)

    Ejiri, Hiroyasu

    2014-09-01

    Neutrino nuclear responses are crucial for neutrino studies in nuclei. Charge exchange reactions (CER) are shown to be used to study charged current neutrino nuclear responses associated with double beta decays(DBD)and astro neutrino interactions. CERs to be used are high energy-resolution (He3 ,t) reactions at RCNP, photonuclear reactions via IAR at NewSUBARU and muon capture reactions at MUSIC RCNP and MLF J-PARC. The Gamow Teller (GT) strengths studied by CERs reproduce the observed 2 neutrino DBD matrix elements. The GT and spin dipole (SD) matrix elements are found to be reduced much due to the nucleon spin isospin correlations and the non-nucleonic (delta isobar) nuclear medium effects. Impacts of the reductions on the DBD matrix elements and astro neutrino interactions are discussed.

  1. Reaction mechanism and nuclear correlations study by low energy pion double charge exchange

    International Nuclear Information System (INIS)

    In pion double-charge-exchange (DCX) reactions, a positive (negative) pion is incident on a nucleus and a negative (positive) pion emerges. These reactions are of fundamental interest since the process must involve at least two nucleons in order to conserve charge. Although two nucleon processes are present in many reactions they are usually masked by the dominant single nucleon processes. DCX is unique in that respect since it is a two nucleon process in lowest order and thus may be sensitive to two-nucleon correlations. Measurements of low energy pion double-charge-exchange reactions to the double-isobaric-analog-state (DIAS) and ground-state (GS) of the residual nucleus provide new means for studying nucleon-nucleon correlations in nuclei. At low energies (Tπ 7/2 shell at energies ranging from 25 to 65 MeV. Cross sections were measured on 42,44,48Ca, 46,50Ti and 54Fe. The calcium isotopes make a good set of nuclei on which to study the effects of correlations in DCX reactions

  2. Beta Decay of Tz=-1 nuclei and Comparison with Charge Exchange Reaction Experiments

    OpenAIRE

    Molina Palacios, Francisco Gabriel

    2011-01-01

    This thesis covers an experimental study of the beta-decay of four Tz=-1 nuclei. The main purpose of this work is to compare these four decays with the mirror process studied in the (3He,t) charge exchange (CE) reaction at RCNP in Osaka, Japan. The experimental work was carried out at two different laboratories, LISOL at the Centre de Recherches du Cyclotron CRC in Louvain-la-Neuve, Belgium and RISING-FRS at the Gesellschaft f¿ur SchwerIonenforschung (GSI) in Darmstadt, Germany. The two fa...

  3. Search for Tetraneutron by Pion Double Charge Exchange Reaction at J-PARC

    CERN Document Server

    Fujioka, Hiroyuki; Harada, Toru; Hiyama, Emiko; Itahashi, Kenta; Kanatsuki, Shunsuke; Nagae, Tomofumi; Nanamura, Takuya; Nishi, Takahiro

    2016-01-01

    Tetraneutron ($^4n$) has come back in the limelight, because of recent observation of a candidate resonant state at RIBF. We propose to investigate the pion double charge exchange (DCX) reaction, i.e. $^4\\mathrm{He}({\\pi}^- , {\\pi}^+)$, as an alternative way to populate tetraneutron. An intense ${\\pi}^-$ beam with the kinetic energy of ~850 MeV, much higher than that in past experiments at LAMPF and TRIUMF, will open up a possibility to improve the experimental sensitivity of the formation cross section, which will be much smaller than hitherto known DCX cross sections such as $^9\\mathrm{Be}({\\pi}^-, {\\pi}^+)^9\\mathrm{He}\\ (g.s.)$.

  4. Analysis of discrete ambiguities for πND and πNα vertex functions using inclusive charge-exchange reactions

    International Nuclear Information System (INIS)

    Within the framework of the formalism of Feynman diagrams to describe the charge-exchange reactions (p,n), (p,n) and 3He,t) on a free proton target taking into account spectator and decay in the π+ρ+g'-model are described. These are partly dissolved if charge-exchange data for a wide energy range are used. 19 refs

  5. Pion nucleus single charge exchange reactions above the Δ(1232) resonance

    International Nuclear Information System (INIS)

    Forward-angle differential cross sections for the (π+, π0) reaction leading to the Isobaric Analog State in the residual nuclei at 300, 425, 500 and 550 MeV have been measured. Targets ranged in mass from 7Li to 208Pb. A description of the experimental setup and the analysis is presented. The 00 cross sections are found to rise markedly between 300 and 425 MeV, contrary to the extrapolation from the lower energy data and to the behavior of the free pion-nucleon single charge exchange process. The angular distributions are sharply forward peaked. Systematics of the data indicate increased volume penetration with increasing pion beam energy. The cross sections are compared with the results of Glauber model calculations indicating the significance of higher order processes even at these energies. 67 refs., 40 figs., 22 tabs

  6. The neutron-proton charge-exchange amplitudes measured in the dp {yields} ppn reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mchedlishvili, D.; Chiladze, D. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); Barsov, S.; Dzyuba, A. [Petersburg Nuclear Physics Institute, High Energy Physics Department, Gatchina (Russian Federation); Carbonell, J. [Universite Paris-Sud, IN2P3-CNRS, Institut de Physique Nucleaire, Orsay Cedex (France); Dymov, S. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Universitaet Erlangen-Nuernberg, Physikalisches Institut II, Erlangen (Germany); Engels, R.; Gebel, R.; Hartmann, M.; Kacharava, A.; Kamerdzhiev, V.; Lehrach, A.; Lorentz, B.; Maier, R.; Ohm, H.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Seyfarth, H.; Stein, H.J.; Stockhorst, H.; Stroeher, H. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); Glagolev, V. [JINR, Laboratory of High Energies, Dubna (Russian Federation); Grigoryev, K.; Mikirtychyants, M.; Mikirtychyants, S.; Valdau, Yu. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); Petersburg Nuclear Physics Institute, High Energy Physics Department, Gatchina (Russian Federation); Goslawski, P.; Khoukaz, A.; Mielke, M.; Papenbrock, M. [Universitaet Muenster, Institut fuer Kernphysik, Muenster (Germany); Keshelashvili, I. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); University of Basel, Department of Physics, Basel (Switzerland); Komarov, V.; Kulikov, A. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Kulessa, P. [H. Niewodniczanski Institute of Nuclear Physics PAN, Krakow (Poland); Lomidze, N.; Nioradze, M.; Tabidze, M. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); Macharashvili, G. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Merzliakov, S. [Forschungszentrum Juelich, Institut fuer Kernphysik and Juelich Centre for Hadron Physics, Juelich (Germany); JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Steffens, E. [Universitaet Erlangen-Nuernberg, Physikalisches Institut II, Erlangen (Germany); Trusov, S. [Forschungszentrum Rossendorf, Institut fuer Kern- und Hadronenphysik, Dresden (Germany); Uzikov, Yu. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); M. V. Lomonosov Moscow State University, Department of Physics, Moscow (Russian Federation); Wilkin, C. [UCL, Physics and Astronomy Department, London (United Kingdom)

    2013-04-15

    The unpolarised differential cross section and the two deuteron tensor analysing powers A{sub xx} and A{sub yy} of the vector dp {yields} {l_brace}pp{r_brace}{sub s}n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27GeV, data were obtained for small momentum transfers to a {l_brace}pp{r_brace}{sub s} system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C{sub x,x} and C{sub y,y} that were carried out in the vector dvector p {yields} {l_brace}pp{r_brace}{sub s}n reaction at 1.2 and 2.27GeV. The values obtained for the proton analysing power A{sub y}{sup p} also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. It is therefore clear that such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region. (orig.)

  7. The neutron-proton charge-exchange amplitudes measured in the dp -> ppn reaction

    CERN Document Server

    Mchedlishvili, D; Carbonell, J; Chiladze, D; Dymov, S; Dzyuba, A; Engels, R; Gebel, R; Glagolev, V; Grigoryev, K; Goslawski, P; Hartmann, M; Kacharava, A; Kamerdzhiev, V; Keshelashvili, I; Khoukaz, A; Komarov, V; Kulessa, P; Kulikov, A; Lehrach, A; Lomidze, N; Lorentz, B; Macharashvili, G; Maier, R; Merzliakov, S; Mielke, M; Mikirtychyants, M; Mikirtychyants, S; Nioradze, M; Ohm, H; Papenbrock, M; Prasuhn, D; Rathmann, F; Serdyuk, V; Seyfarth, H; Stein, H J; Steffens, E; Stockhorst, H; Stroeher, H; Tabidze, M; Trusov, S; Uzikov, Yu; Valdau, Yu; Wilkin, C

    2012-01-01

    The unpolarised differential cross section and the two deuteron tensor analysing powers A_{xx} and A_{yy} of the pol{d}p -> (pp)n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27 GeV, data were obtained for small momentum transfers to a (pp) system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C_{x,x} and C_{y,y} that were carried out in the pol{d}pol{p} -> (pp)n reaction at 1.2 and 2.27GeV. The values obtained for the proton analysing power also suggest th...

  8. Charge exchange system

    Science.gov (United States)

    Anderson, Oscar A.

    1978-01-01

    An improved charge exchange system for substantially reducing pumping requirements of excess gas in a controlled thermonuclear reactor high energy neutral beam injector. The charge exchange system utilizes a jet-type blanket which acts simultaneously as the charge exchange medium and as a shield for reflecting excess gas.

  9. Resonant behaviour in double charge exchange reaction of π+-mesons on the nuclear photoemulsion

    International Nuclear Information System (INIS)

    The invariant-mass spectra of the ppπ- and pp systems produced in the double charge exchange (DCX) of positively charged pions on photoemulsion are analysed. A pronounced peak is observed in the ppπ- invariant-mass spectrum, while the Mpp spectrum exhibits a strong Migdal-Watson effect of the proton-proton final-state interaction. These findings are in favor of the NN-decoupled NN π pseudoscalar resonance with T=0 called d'

  10. Charge-exchange reactions from the standpoint of the parton model

    Energy Technology Data Exchange (ETDEWEB)

    Nekrasov, M.L. [SRC Institute for High Energy Physics of NRC ' ' Kurchatov Institute' ' , Protvino (Russian Federation)

    2015-11-15

    Using simple arguments, we show that charge-exchange reactions at high energies go through the hard scattering of fast quarks. On this basis we describe π{sup -}p → M{sup 0}n and K{sup -}p → M{sup 0}Λ, M{sup 0} = π{sup 0},η,η', in a combined approach which defines hard contributions in the parton model and soft ones in Regge phenomenology. The disappearance of a dip according to recent GAMS-4π data in the differential cross-section K{sup -}p → ηΛ at vertical stroke t vertical stroke ∼ 0.4-0.5 (GeV/c){sup 2} at transition to relatively high momenta, is explained as a manifestation of a mode change of summation of hard contributions from coherent to incoherent. Other manifestations of the mentioned mode change are discussed. Constraints on the η - η' mixing and gluonium admixture in η' are obtained. (orig.)

  11. 36-MeV-triton-induced charge exchange: Mass measurements and energy levels of neutron-rich nuclei and the charge exchange reaction mechanism

    International Nuclear Information System (INIS)

    Energy spectra and differential cross sections have been obtained for the charge exchange reaction (3H,3He) on targets of /sup 30,28/Si and /sup 26/Mg at an incident energy of 36 MeV. Previously unobserved energy levels of /sup 30/Al and /sup 26/Na are reported and compared to shell model predictions. Microscopic form factors based on the M3Y effective nucleon-nucleon interaction are used in distorted-wave Born approximation codes to fit the data. The sensitivity of the model to input parameters is discussed and some spin assignments made. Coupled channels calculations are performed to fit the two-step contributions to the data via sequential one-nucleon transfers

  12. Heavy-ion double charge exchange reactions: a tool towards 0v\\b{eta}\\b{eta} nuclear matrix elements

    CERN Document Server

    Cappuzzello, F; Agodi, C; Bond`ı, M; Carbone, D; Cunsolo, A; Foti, A

    2015-01-01

    The knowledge of the nuclear matrix elements for the neutrinoless double beta decay is fundamental for neutrino physics. In this paper, an innovative technique to extract information on the nuclear matrix elements by measuring the cross section of a double charge exchange nuclear reaction is proposed. The basic point is that the initial and final state wave functions in the two processes are the same and the transition operators are similar. The double charge exchange cross sections can be factorized in a nuclear structure term containing the matrix elements and a nuclear reaction factor. First pioneering experimental results for the 40Ca(18O,18Ne)40Ar reaction at 270 MeV incident energy show that such cross section factorization reasonably holds for the crucial 0+ --> 0+ transition to 40Args, at least at very forward angles.

  13. Heavy-ion double charge exchange reactions: A tool toward 0 νββ nuclear matrix elements

    Energy Technology Data Exchange (ETDEWEB)

    Cappuzzello, F.; Bondi, M. [Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); INFN, Laboratori Nazionali del Sud, Catania (Italy); Cavallaro, M.; Agodi, C.; Carbone, D.; Cunsolo, A. [INFN, Laboratori Nazionali del Sud, Catania (Italy); Foti, A. [Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); INFN, Sezione di Catania, Catania (Italy)

    2015-11-15

    The knowledge of the nuclear matrix elements for the neutrinoless double beta decay is fundamental for neutrino physics. In this paper, an innovative technique to extract information on the nuclear matrix elements by measuring the cross section of a double charge exchange nuclear reaction is proposed. The basic point is that the initial- and final-state wave functions in the two processes are the same and the transition operators are similar. The double charge exchange cross sections can be factorized in a nuclear structure term containing the matrix elements and a nuclear reaction factor. First pioneering experimental results for the {sup 40}Ca({sup 18}O,{sup 18}Ne){sup 40}Ar reaction at 270 MeV incident energy show that such cross section factorization reasonably holds for the crucial 0{sup +} → 0{sup +} transition to {sup 40}Ar{sub gs}, at least at very forward angles. (orig.)

  14. Charge-exchange breakup of the deuteron with the production of two protons and spin structure of the amplitude of the nucleon charge transfer reaction

    International Nuclear Information System (INIS)

    In the framework of the impulse approximation, the relation between the effective cross section of the charge-exchange breakup of a fast deuteron d + a → (pp) + b and the effective cross section of the charge transfer process n + a → p + b is discussed. In doing so, the effects of the proton identity (Fermi-statistics) and of the Coulomb and strong interactions of protons in the final state are taken into account. The distribution over relative momenta of the protons, produced in the charge-exchange process d + p → (pp) + n in the forward direction, is investigated. At the transfer momenta being close to zero the effective cross section of the charge-exchange breakup of a fast deuteron, colliding with the proton target, is determined only by the spin-flip part of the amplitude of the charge transfer reaction n + p → p + n at the zero angle. It is shown that the study of the process d + p → (pp) + n in a beam of the polarized (aligned) deuterons allows one, in principle, to separate two spin-dependent terms in the amplitude of the charge transfer reaction n + p → p + n, one of which does not conserve and the other one conserves the projection of the nucleon spin onto the direction of momentum at the transition of the neutron into the proton

  15. Coherent production of pions in nuclei with (3He,t) charge exchange reaction at 2. GeV

    International Nuclear Information System (INIS)

    The (3He,t) charge exchange reaction at 2. GeV incident energy with the new setup SPES IV-π has been realized in order to study the coherent production process of pions. This setup allows to isolate the ground state of the target nucleus, and to sign this process without ambiguity. Some preliminary results in target excitation energy and transferred energy are given. (author)

  16. Momentum dependence of spin polarization for beta emitting nuclei produced through charge exchange reaction at intermediate energy

    Energy Technology Data Exchange (ETDEWEB)

    Momota, S., E-mail: momota.sadao@kochi-tech.ac.jp [Kochi University of Tech. (Japan); Mihara, M. [Osaka University (Japan); Nishimura, D. [RIKEN (Japan); Fukuda, M.; Kamisho, Y.; Wakabayashi, M.; Matsuta, K. [Osaka University (Japan); Suzuki, S.; Nagashima, M. [Niigata University (Japan); Zhu, Shengyun; Yuan, Daqing; Zheng, Yongnan; Yi, Zuo; Fan, Ping [CIAE (China); Izumikawa, T. [Niigata University, RI Center (Japan); Kitagawa, A.; Sato, S.; Kanazawa, M.; Torikoshi, M. [NIRS (Japan); Minamisono, T. [Osaka University (Japan); and others

    2013-05-15

    In order to investigate the polarization process in charge exchange reactions, we observed the momentum and angular distribution as well as the nuclear polarization of a proton-rich beta-emitting nucleus, {sup 28}P (I{sup {pi}} = 3{sup +}, T{sub 1/2} = 270 msec), produced through the reaction {sup 28}Si+ {sup 9}Be at E = 100 MeV/u, by selecting the momentum and the ejection angle. An analysis by using double Gaussian functions resolved the observed momentum distribution into two reaction components, nucleon knockout and pick-up abrasion reactions, as suggested in a previous study. The behavior of the observed angular distribution and nuclear polarization implies the influence of those two components. The momentum dependence of the observed nuclear polarization of {sup 28}P could be consistently reproduced by a simple model, in which two reaction components are considered. The present study also shows that the charge exchange reaction at intermediate energy is a useful method to produce polarized beta-emitting nuclei, especially for proton-rich nuclei.

  17. Study of the pd→→n{pp}s charge-exchange reaction using a polarised deuterium target

    Directory of Open Access Journals (Sweden)

    B. Gou

    2015-02-01

    Full Text Available The vector and tensor analysing powers, Ay and Ayy, of the pd→→n{pp}s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S01 state, here denoted by {pp}s. The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q≥160 MeV/c. These data provide a good continuation of the earlier results at q≤140 MeV/c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

  18. Inelastic process observed in charge-exchange reactions of 56Fe at 500 MeV/u

    Directory of Open Access Journals (Sweden)

    Momota S.

    2014-03-01

    Full Text Available The inelastic (IE component of the reaction product, which is produced through charge-exchange reactions at relativistic energies of E ~ 1 GeV/u, is one of the hopeful probes used to study the nuclear medium effect on Δ excitation. In the present study, the longitudinal-momentum (PL distribution of 56Co, produced by bombarding C-and CH2-target with a primary beam of 56Fe at E=500 MeV/u, was observed by means of the spectrometer at HIMAC facility. The IE peak of 56Co, produced from H and C targets, was successfully observed in energy transfer spectrum. The behaviors of the IE peaks are consistent with those observed in previous experiments. A remarkable reduction of the energy transfer for the IE process was also observed with C target compared with H target. The present results have shown the feasibility to investigate the energy transfer in charge-exchange reactions for heavy reaction system at the energy down to 500 MeV/u.

  19. NUMEN Project @ LNS : Heavy ions double charge exchange reactions towards the 0νββ nuclear matrix element determination

    International Nuclear Information System (INIS)

    In the NUMEN Project it is proposed an innovative technique to access the nuclear matrix elements entering in the expression of the life-time of the neutrinoless double beta decay, using relevant cross sections of double charge exchange reactions. A key aspect is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN Laboratori Nazionali del Sud (LNS) K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams

  20. NUMEN Project @ LNS : Heavy ions double charge exchange reactions towards the 0νββ nuclear matrix element determination

    Science.gov (United States)

    Agodi, C.; Cappuzzello, F.; Bonanno, D. L.; Bongiovanni, D. G.; Branchina, V.; Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Cuttone, G.; Foti, A.; Finocchiaro, P.; Greco, V.; Lanzalone, G.; Lo Presti, D.; Longhitano, F.; Muoio, A.; Pandola, L.; Rifuggiato, D.; Tudisco, S.

    2015-10-01

    In the NUMEN Project it is proposed an innovative technique to access the nuclear matrix elements entering in the expression of the life-time of the neutrinoless double beta decay, using relevant cross sections of double charge exchange reactions. A key aspect is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN Laboratori Nazionali del Sud (LNS) K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  1. NUMEN Project @ LNS : Heavy ions double charge exchange reactions towards the 0νββ nuclear matrix element determination

    Energy Technology Data Exchange (ETDEWEB)

    Agodi, C., E-mail: agodi@lns.infn.it; Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Cuttone, G.; Finocchiaro, P.; Pandola, L.; Rifuggiato, D.; Tudisco, S. [INFN - Laboratori Nazionali del Sud, Catania (Italy); Cappuzzello, F.; Greco, V. [INFN - Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Bonanno, D. L.; Bongiovanni, D. G.; Longhitano, F. [INFN - Sezione di Catania, Catania (Italy); Branchina, V. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); Foti, A.; Lo Presti, D. [Dipartimento di Fisica e Astronomia, Università di Catania, Catania (Italy); INFN - Sezione di Catania, Catania (Italy); Lanzalone, G. [Università di Enna, Enna (Italy); and others

    2015-10-28

    In the NUMEN Project it is proposed an innovative technique to access the nuclear matrix elements entering in the expression of the life-time of the neutrinoless double beta decay, using relevant cross sections of double charge exchange reactions. A key aspect is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN Laboratori Nazionali del Sud (LNS) K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  2. Polarized deuteron charge-exchange reaction $dp->{pp}_sN\\pi$ in the Delta-isobar region

    OpenAIRE

    Uzikov, Yu. N.; Haidenbauer, J.; Wilkin, C.

    2015-01-01

    Mechanisms of the charge exchange reaction $dp\\to \\{pp\\}_{\\!s} N\\pi$, where $\\{pp\\}_{\\!s}$ is a two-proton system at low excitation energy, are studied at beam energies 1 -- 2 GeV and for invariant masses $M_X$ of the final $N\\pi $ system that correspond to the formation of the $\\Delta(1232)$ isobar. The direct mechanism, where the initial proton is excited into the $\\Delta(1232)$, dominates and explains the existing data on the unpolarized differential cross section and spherical tensor anal...

  3. Measurement and study of the differential cross section variations corresponding to the n+p→p+n charge exchange reaction between 1 and 2GeV/c

    International Nuclear Information System (INIS)

    Twenty one differential cross section measurements for the np→pn charge exchange reaction have been carried out at the synchrotron Saturne (Saclay) for incident neutron momenta between 1 and 2GeV/c by step of 50MeV/c and in the squared four momentum transfer range 02. The results show that the mechanism of π exchange in the t-channel is clearly present at all the incident momenta; that is confirmed by the agreement with the ''poor man's absorption'' model, based on π exchange, in the range 02. The s dependence of the charge exchange peak shows weak structures which can be associated with the opening of the inelastic channel NΔ(1236) and NN*(1400). The results of an analysis of a set of np→pn amplitudes constructed from NN helicity amplitudes confirm that the π exchange in the t-channel is dominant in the charge exchange reaction

  4. Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

    International Nuclear Information System (INIS)

    Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and 3He ions, respectively. When the plasma was compressed, the d(d,n)3He fusion reaction rate increased a factor of five, and the 3He(d,p)4He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling

  5. Study of electric isovector giant nuclear resonances by the charge exchange reaction. Search for a monopole mode

    International Nuclear Information System (INIS)

    Charge exchange reactions (13C, 13N) and (13C, 13B) at 50 MeV/n are studied with the purpose of investigating the electric isovector modes of giant nuclear resonances in 12C, 40Ca, 58Ni, 60Ni, 90Zr, 120Sn and 208Pb, and especially the monopole mode. Measurements have been performed at GANIL, using the magnetic spectrometer SPEG. The main characteristics of giant nuclear resonances are reviewed, and the ability of the chosen reactions to excite electric isovector modes is examined. Experimental setup and data reduction are described. Results are commented and analyzed. The analog state of the dipole resonance is strongly excited in nuclei with A ≤ 60; excitation energies and widths are obtained with a good accuracy. For nuclei with A ≥ 60, a large peak is observed in the spectra. Its excitation energy is closed to the excitation energy of the giant isovector monopole resonance, measured with the (π-, π0) reaction, except in 208Pb. Experimental angular distributions do not quite show the features expected from DWBA calculations. The low-lying states of 12N and 12B are used to test the calculations and the reaction mechanisms

  6. The dp{yields}ppn reaction as a method to study neutron-proton charge-exchange amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Chiladze, D. [Tbilisi State Univ., High Energy Physics Inst., Tbilisi (Georgia); Forschungszentrum Juelich GmbH, Institut fuer Kernphysik, Juelich (Germany); Juelich Centre for Hadron Physics, Juelich (Germany); Carbonell, J. [Laboratoire de Physique Subatomique et de Cosmologie, Grenoble (France); Dymov, S. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Universitaet Erlangen-Nuernberg, Physikalisches Institut II, Erlangen (Germany); Dzyuba, A.; Valdau, Yu. [Petersburg Nuclear Physics Institute, High Energy Physics Department, Gatchina (Russian Federation); Glagolev, V. [JINR, Laboratory of High Energies, Dubna (Russian Federation); Hartmann, M.; Kacharava, A.; Nekipelov, M.; Ohm, H.; Rathmann, F.; Stroeher, H. [Forschungszentrum Juelich GmbH, Institut fuer Kernphysik, Juelich (Germany); Juelich Centre for Hadron Physics, Juelich (Germany); Keshelashvili, I. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); University of Basel, Department of Physics, Basel (Switzerland); Khoukaz, A.; Mersmann, T.; Mielke, M. [Universitaet Muenster, Institut fuer Kernphysik, Muenster (Germany); Komarov, V.; Kulikov, A.; Uzikov, Yu. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Kulessa, P. [H. Niewodniczanski Institute of Nuclear Physics PAN, Krakow (Poland); Lomidze, N.; Mchedlishvili, D.; Nioradze, M.; Tabidze, M. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); Macharashvili, G. [Tbilisi State University, High Energy Physics Institute, Tbilisi (Georgia); JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Maeda, Y. [Osaka University, Research Center for Nuclear Physics, Osaka Ibaraki (Japan); Merzliakov, S. [Forschungszentrum Juelich GmbH, Institut fuer Kernphysik, Juelich (Germany); Juelich Centre for Hadron Physics, Juelich (Germany); JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation)] [and others

    2009-04-15

    The differential cross section and deuteron analysing powers of the (vector)dp{yields}{l_brace}pp{r_brace}n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using a deuteron beam of energy 1170MeV, data were obtained for small momentum transfers to a {l_brace}pp{r_brace} system with low excitation energy. A good quantitative understanding of all the measured observables is provided by the impulse approximation using known neutron-proton amplitudes. The proof of principle achieved here for the method suggests that measurements at higher energies will provide useful information in regions where the existing np database is far less reliable. (orig.)

  7. Polarized deuteron charge-exchange reaction $dp->{pp}_sN\\pi$ in the Delta-isobar region

    CERN Document Server

    Uzikov, Yu N; Wilkin, C

    2015-01-01

    Mechanisms of the charge exchange reaction $dp\\to \\{pp\\}_{\\!s} N\\pi$, where $\\{pp\\}_{\\!s}$ is a two-proton system at low excitation energy, are studied at beam energies 1 -- 2 GeV and for invariant masses $M_X$ of the final $N\\pi $ system that correspond to the formation of the $\\Delta(1232)$ isobar. The direct mechanism, where the initial proton is excited into the $\\Delta(1232)$, dominates and explains the existing data on the unpolarized differential cross section and spherical tensor analyzing power $T_{22}$ for $M_X> 1.2$ GeV/$c^2$. However, this model fails to describe $T_{20}.

  8. Charge exchange cross sections for the reaction Xe+8 + Xe+8 → Xe+9 + Xe+7

    International Nuclear Information System (INIS)

    The charge changing cross sections for self collisions of Xe+8 ions with 0 to 150 keV relative translational kinetic energy are estimated on the basis of the Fano-Lichten electron promotion model. It is concluded that for Xe+8 + Xe+8, charge changing collisions occur only infrequently compared to excitation and with cross sections much smaller than 10-18 cm2

  9. Excitation of the Δ resonance in the nuclear medium through charge exchange reactions

    International Nuclear Information System (INIS)

    Data are presented on the decay of the Δ resonance excited in lH, 2H and 12C by the (3He,t) reaction at 2 GeV incident energy. In the energy transfer spectra, the same position and width of the Δ resonance have been observed on the three targets when one π+ and one proton is detected in coincidence with the triton. On the 12C target, the Δ peak associated with the detection of 2 protons is shifted by 100 MeV towards lower excitation energy. (authors) 14 refs., 5 figs

  10. Interference effects in inclusive charge-exchange p+p→n+X and n+p→p+X reactions at intermediate energies

    International Nuclear Information System (INIS)

    The formalism of Feynman diagrams to describe charge-exchange reactions p+p→n+X and n+p→p+X on a free proton target taking into account spectator and decay modes in the π+ρ+g'-model have used. It is shown that the interference between these modes depends on the set of vertex function parameters used. It is also shown that the constructive interference of the Δ+ and Δ0-isobars is important. 22 refs.; 10 figs

  11. $\\beta$- decay of $^{58}$Zn. A critical test for the charge-exchange reaction as a probe for the $\\beta$- decay strength distribution

    CERN Multimedia

    2002-01-01

    % IS353 \\\\ \\\\ Due to its importance in fundamental physics and astrophysics, a great effort both theoretically and experimentally is devoted to study Gamow Teller (GT)-strength. The GT-strength and its distribution play a key role in late stellar evolution. During the pre-supernova core-collapse of massive stars, the electron capture and nuclear $\\beta$ -decay determine the electron-to-baryon ratio, which influences the infall dynamics and the mass of the final core. The cross-section of the charge-exchange reaction at forward angles with energies above 100~MeV is expected to be proportional to the squares of Fermi and GT matrix elements. This proportionality should provide a Q-value free method to probe the weak interaction strength and renormalization effects in nuclei. Thus charge-exchange reactions are often used to determine the experimental GT-strength. However, the connection between the GT-strength and the cross-section of the charge-exchange reaction is partially model-dependent and the question aris...

  12. Total cross sections of the charge exchange reaction (π+,π0) on 2H, 3He, and 4He across the Δ(1232) resonance

    International Nuclear Information System (INIS)

    Results from a 4π solid angle measurement of the inclusive reaction (π+,π0) on 2H, 3He, and 4He at incident pion energies of Tπ+=70, 118, 162, 239, and 330 MeV are presented. The single charge exchange total cross sections were determined, and are compared to previous results and simple models of π endash few-nucleon interactions. On the helium isotopes a strong damping of the cross sections in the Δ(1232) energy region is observed. Total cross sections of the breakup reaction π++2H →π+pn are also given. copyright 1999 The American Physical Society

  13. Hydrogen isotope exchange reactions

    International Nuclear Information System (INIS)

    The two most widely used methods for following hydrogen isotope exchange reactions, namely dedeuteriation and detritiation, involve in the first place the synthesis of an appropriately labelled compound. Rates of dedeuteriation are usually followed by measuring changes in the 1H n.m.r. spectrum of the substrate (examples are given); the method not only gives the rate but also the site(s) of exchange. It is limited to rather slow reactions and is not as accurate as some of the other methods. The development of deuterium n.m.r. spectroscopy means that changes in the 2H n.m.r. spectrum can also be used to measure rates of dedeuteriation. The development of liquid scintillation counting greatly eased the problem of how to detect weak β emitters; the attractions of tritium as a tracer were thereby much enhanced. Nowadays the study of rates of detritiation constitutes one of the most versatile and accurate methods of following hydrogen isotope exchange. Examples of the technique are given. (U.K.)

  14. Inclusive measurement of (p,πsup(-)xn) double charge exchange reactions on bismuth from threshold to 800 MeV

    International Nuclear Information System (INIS)

    The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,πsup(-)xn) double charge exchange reactions on bismuth (sup(209)Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of sup(211)At activity in thin (approximately 1 mg/cmsup(2)), irradiated bismuth targets. Calculations of the contributions of secondary (2-step) reactions to these measured astatine yields were performed, based partially upon the observed sup(211)At activity although even at the highest energies, the contribution to products lighter than sup(207)At was negligible. These data for products with as many as 7 neutrons removed from the doubly coherent product (sup(210)At) display nearby gaussian shapes for the mass distributions of the astatine residues with the maximum occurring for about sup(204)At. The most probable momentum transfer deduced from these distributions for the initial πsup(-) production step was 335 MeV/c. The observed excitation functions display a behaviour similar to that observed for the yield of sup(210)Po from a (p,πsup(O)) reaction on sup(209)Bi, but radically different from that observed for inclusive πsup(-) reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive πsup(-) emission which is observed for this double charge exchange reaction. This model reflects the capacity of a nucleus to a source of internal energetic protons

  15. Study of the $\\vec{p}d \\to n\\{pp\\}_{s}$ charge-exchange reaction using a polarised deuterium target

    CERN Document Server

    Gou, B; Bagdasarian, Z; Barsov, S; Chiladze, D; Dymov, S; Engels, R; Gaisser, M; Gebel, R; Grigoryev, K; Hartmann, M; Kacharava, A; Khoukaz, A; Kulessa, P; Kulikov, A; Lehrach, A; Li, Z; Lomidze, N; Lorentz, B; Macharashvili, G; Merzliakov, S; Mielke, M; Mikirtychyants, M; Mikirtychyants, S; Nioradze, M; Ohm, H; Prasuhn, D; Rathmann, F; Serdyuk, V; Seyfarth, H; Shmakova, V; Ströher, H; Tabidze, M; Trusov, S; Tsirkov, D; Uzikov, Yu; Valdau, Yu; Wang, T; Weidemann, C; Wilkin, C; Yuan, X

    2014-01-01

    The vector and tensor analysing powers, $A_y$ and $A_{yy}$, of the $\\vec{p}d \\to n\\{pp\\}_{s}$ charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the $^{1}S_{0}$ state, here denoted by $\\{pp\\}_{s}$. The polarisation of the deuterium gas was established through measurements in parallel of proton-deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers $q\\geq 160$ MeV/$c$. These data provide a good continuation of the earlier results at $q\\leq 140$ MeV/$c$ obtained with a polarised deuteron beam. They are also consistent wi...

  16. Positive-pion double-charge-exchange reaction: experiments on the isotopic pairs oxygen-16,18 and magnesium-24,26

    International Nuclear Information System (INIS)

    The (π+,π-) double-charge-exchange (DCX) reaction has been performed on targets of T = 0,1 isospin (and isotopic) pairs 1618O and 2426Mg. Energy excitation functions of d sigma/d Ω, across the (3,3) π-N resonance, are presented for transitions to double-isobaric analog state (DIAS) and non-DIAS ground-state residual nuclei. Angular distributions in the region of 50 to 330 are presented for the DIAS from the T = 1 nuclei. The similarities and differences of DIAS and non-DIAS distributions are discussed in relation to reaction-mechanism and nuclear-structure effects. Also, a simple, two-amplitude model for the 18O excitation function, consistent with the data, is presented. The utility of DCX in nuclear mass measurements is discussed, with some examples

  17. Positive-pion double-charge-exchange reaction: experiments on the isotopic pairs oxygen-16,18 and magnesium-24,26

    Energy Technology Data Exchange (ETDEWEB)

    Greene, S.J.

    1981-06-01

    The (..pi../sup +/,..pi../sup -/) double-charge-exchange (DCX) reaction has been performed on targets of T = 0,1 isospin (and isotopic) pairs /sup 16/ /sup 18/O and /sup 24/ /sup 26/Mg. Energy excitation functions of d sigma/d ..cap omega.., across the (3,3) ..pi..-N resonance, are presented for transitions to double-isobaric analog state (DIAS) and non-DIAS ground-state residual nuclei. Angular distributions in the region of 5/sup 0/ to 33/sup 0/ are presented for the DIAS from the T = 1 nuclei. The similarities and differences of DIAS and non-DIAS distributions are discussed in relation to reaction-mechanism and nuclear-structure effects. Also, a simple, two-amplitude model for the /sup 18/O excitation function, consistent with the data, is presented. The utility of DCX in nuclear mass measurements is discussed, with some examples.

  18. Expressions for Form Factors for Inelastic Scattering and Charge Exchange in Plane-Wave, Distorted-Wave, and Coupled-Channels Reaction Formalisms

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, F S

    2006-09-25

    This document is intended to facilitate calculation of inelastic scattering and charge-exchange cross sections in a variety of reaction models, including the plane-wave and distorted-wave approximations and the full coupled-channels treatments. Expressions are given for the coupling potentials between the relevant channels in both coordinate and momentum space. In particular, it is expected that the plane-wave calculations should be useful as a check on the correctness of coupled-channels calculations. The Fourier transform methods used to calculate the plane-wave approximation cross sections are also intended to be used to generate the transition potentials for coupled-channels codes, using a folding model with local effective interactions. Specific expressions are given for calculating transition densities for the folding model in the random phase approximation (RPA).

  19. Systematics of pion double charge exchange

    International Nuclear Information System (INIS)

    Differential cross sections have been measured for pion-induced double-charge-exchange (DCX) reactions leading to double-isobaric-analog states (DIAS) and low-lying nonanalog states in the residual nuclei. A description of the experimental details and data analysis is presented. The experimentally observed systematics of reactions leading to DIAS, to nonanalog ground states, and to low-lying 2+ states are described. Lowest-order optical-model calculations of DIAS DCX are compared to the data. Efforts to understand the anomalies by invoking additional reaction-mechanism amplitudes and a higher-order optical potential are described. Calculations of nonanalog DCX reactions leading to J/sup π/ = 0+ states were performed within a distorted-wave impulse-approximation framework. The sensitivities of these calculations to input parameters are discussed. 58 refs., 41 figs., 16 tabs

  20. Charge-exchange straggling in equilibrium

    Energy Technology Data Exchange (ETDEWEB)

    Sigmund, P. [Department of Physics and Chemistry, University of Southern Denmark, DK-5230 Odense M (Denmark); Osmani, O. [Department of Physics, University of Duisburg-Essen, D-47048 Duisburg (Germany); Department of Physics, University of Kaiserslautern and Research Center OPTIMAS, D-67653 Kaiserslautern (Germany); Schinner, A. [Institut fuer Experimentalphysik, Johannes, Kepler Universitaet, A-4040 Linz (Austria)

    2011-05-01

    A general expression has been derived that allows computation of charge-exchange straggling of swift heavy ions when many charge states are involved. Charge exchange is found to hinge on the variation of the stopping cross section with the ion charge and on the transient behavior of the charge population as a function of traveled pathlength. These effects appear factorized in the final formula. The focus of this paper is on straggling in charge equilibrium. The case of MeV/u sulfur ions in carbon has been used as an illustration. Charge-exchange straggling is found to be dominating straggling over a considerable range of beam energies.

  1. Intermediate energy nuclear physics (Task C) and charge exchange reactions (Task W). Progress report, October 1, 1983-September 30, 1984

    International Nuclear Information System (INIS)

    This report summarizes work carried out between October 1, 1983 and October 1, 1984 in the Nuclear Physics Laboratory in the Department of Physics at the University of Colorado, Boulder. The major part of the report describes work carried out under two separate contracts with the United States Department of Energy. The first contract supports the theoretical research program and the latter the work in experimental intermediate energy nuclear physics. The experimental research contract is divided into two separate tasks, C and W. Task C covers intermediate energy physics in general and Task W supports study of the (p,n) reaction at the WNR facility at LAMPF. In addition to the work supported by the described contracts, other efforts in the laboratory, such as LAMPF II accelerator development and several projects in low-energy nuclear physics, are described in this report

  2. Measurement of the differential cross-section of the pion-nucleon-charge-exchange reaction at Serpukhov energies

    International Nuclear Information System (INIS)

    We report about a high statistics measurement of the reaction PI-rho → PIon at 15, 25 and 40 GeV/c incident pion momenta. More than one million events of this type have been recorded. The γ's from the PIo-decay have been measured in a spectrometer, which consists of iron-plates and scintillation hodoscopes. The differential cross-sections are determined for momentum transfers up to -t=1.8 (GeV/c)2. The extrapolated cross-sections at t=0, together with the optical theorem, give the differences of the total PI+-rho-cross-sections. They are in good agreement with the measured values. (orig.)

  3. Exchange Reactions. Proceedings of the Symposium on Exchange Reactions

    International Nuclear Information System (INIS)

    The mechanisms and kinetics of chemical reactions are of great interest to chemists. The study of exchange reactions in particular helps to shed light on the dynamics of chemical change, providing an insight into the structures and the reactivities of the chemical species involved. The main theme of this meeting was the subject of oxidation-reduction reactions in which the net result is the transfer of one or more electrons between the different oxidation states of the same element. Other studies reported included the transfer of protons, atoms, complex ligands or organic radicals between molecules. Heterogeneous exchange, which is of importance in many cases of catalytic action, was also considered. For a long time isotopic tracers have formed the most convenient means of studying exchange reactions and today a considerable amount of work continues to be done with their aid. Consequently, several papers presented at this Symposium reported on work carried out by purely radiochemical tracer methods. In recognition, however, of the important role which nuclear magnetic resonance and electron spin resonance play in this field, in particular in the study of fast reactions, a number of reports on investigations in which these techniques had been used was included in the programme. By kind invitation of the United States Government the Symposium on Exchange Reactions was held from 31 May to 4 June at the Brookhaven National Laboratory, Upton, Long Island, N.Y., USA. It was attended by 46 participants from nine countries and one inter-governmental organization. The publication of these Proceedings makes the contents of the papers and the discussion available to a wider audience

  4. The measurement of the total cross section for deep inelastic neutrino-iron and antineutrino-iron reactions with charge exchange

    International Nuclear Information System (INIS)

    The cross section for deep inelastic neutrino-iron and antineutrino-iron charge-exchange reactions was determined. The experiment was performed in the CERN-NBB at hadron beam momenta of 100 GeV/c, 160 GeV/c, and 200 GeV/c with both polarities. The events were registrated with the improved CDHS detector. The flux determination ensued indirectly via the measurement of the hadron flux respectively the muon flux. The neutrino flux determined by both methods agrees well. Within the accessible neutrino energy range (10 GeV ν ν = 0.331±0.003±0.009 ( . 10-38 cm2 (nucl. . GeV)-1), σν/Eν = 0.703±0.002±0.019 ( . 10-38 cm2 (nucl. . GeV)-1), and σ sub(anti ν)/σν = 0.471±0.005±0.007. The first error indication means the statistical, the second the systematical error. The systematic error is mainly conditioned by uncertainties in the flux determination. (orig./HSI)

  5. Impurity charge-exchange processes in Tokamak plasmas

    International Nuclear Information System (INIS)

    Charge-exchange reactions between multiply-charged impurity ions and neutral hydrogen isotopes are considered. Ionization equilibrium and radiative losses are evaluated for oxygen and iron in the presence of either 'thermal' or 'beam' neutrals. The influence of 'thermal' neutrals on recently reported results from ohmically heated TFR discharges is also discussed

  6. Probing nuclear correlations with pion-nucleus double charge exchange

    International Nuclear Information System (INIS)

    In this paper we have calculated the lowest order pion double charge reaction mechanism using shell model wavefunctions of medium weight nuclei. We have the sequential reaction mechanism in which the pion undergoes two single-charge exchange scatterings on the valence neutrons. The distortion of the incoming, intermediate, and outgoing pion are included. The closure approximation is made for the intermediate states with an average excitation energy used in the pion propagator. The double-charge exchange is assumed to take place on the valence nucleons which are assumed to be in one spherical shell model orbital. 34 refs., 5 figs., 3 tabs

  7. Charge-exchange giant resonances as probes of nuclear structure

    International Nuclear Information System (INIS)

    Giant resonances populated in charge-exchange reactions can reveal detailed information about nuclear structure properties, in spite of their apparent featurelessness. The (p,n) and (n,p) reactions - as well as their analog reactions - proceed via the same nuclear matrix element as beta decay. Thereby, they are useful for probing electroweak properties in nuclei, especially for those not accessible to beta decay. The nuclear physics aspects of double beta decay might be investigated in double charge-exchange reactions. detailed nuclear structure information, such as the presence of ground-state correlations, can be revealed via identification of 'first-forbidden' transitions. In addition, astrophysics aspects and halo properties of nuclei have been investigated in charge exchange. Finally, these experiments have questioned our knowledge of the absolute strength of the strong interaction

  8. Charge-exchange giant resonances as probes of nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Blomgren, J. [Uppsala Univ., (Sweden). Dept. of Neutron Research

    2001-09-01

    Giant resonances populated in charge-exchange reactions can reveal detailed information about nuclear structure properties, in spite of their apparent featurelessness. The (p,n) and (n,p) reactions - as well as their analog reactions - proceed via the same nuclear matrix element as beta decay. Thereby, they are useful for probing electroweak properties in nuclei, especially for those not accessible to beta decay. The nuclear physics aspects of double beta decay might be investigated in double charge-exchange reactions. detailed nuclear structure information, such as the presence of ground-state correlations, can be revealed via identification of 'first-forbidden' transitions. In addition, astrophysics aspects and halo properties of nuclei have been investigated in charge exchange. Finally, these experiments have questioned our knowledge of the absolute strength of the strong interaction.

  9. Extension of a Kinetic-Theory Approach for Computing Chemical-Reaction Rates to Reactions with Charged Particles

    Science.gov (United States)

    Liechty, Derek S.; Lewis, Mark J.

    2010-01-01

    Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties (i.e., no macroscopic reaction rate information) are extended to include reactions involving charged particles and electronic energy levels. The proposed extensions include ionization reactions, exothermic associative ionization reactions, endothermic and exothermic charge exchange reactions, and other exchange reactions involving ionized species. The extensions are shown to agree favorably with the measured Arrhenius rates for near-equilibrium conditions.

  10. Gaseous charge transfer reactions of multiply charged ions

    International Nuclear Information System (INIS)

    Doubly charged ions produced in electron impact ionization have received relatively little study due to their low abundance and masking from singly charged ions which are detected at the same mass-to-charge ratio by a mass spectrometer. This interference problem was avoided by exploiting a technique in which doubly charged molecular and fragment ions are monitored using a collisional charge-exchange process where only fast singly charged product ions are allowed to reach the detector. Primary research efforts were to determine structures and energetics of multiply charged ions formed in high energy electron impact ionization processes and their reactivities in ion-molecule charge exchange interactions. Doubly charged ion mass distributions for various chemical classes (including acetylenes, alkenes, terpenes and organophosphorus compounds) were recorded and appearance energies of prominent doubly charged ions were measured. Computer molecular orbital calculations (at the MINDO/3 level) of ionic structures, energies and charge distributions were utilized to augment the analysis of experimental results

  11. High-resolution study of the Gamow-Teller strength distribution in the light nuclei 9B and 13N using the (3He,t) charge-exchange reaction at 420 MeV beam energy

    International Nuclear Information System (INIS)

    Excited states in the light nuclei 9B and 13C were studied using the (3He,t) charge-exchange reaction on 9Be and 13C targets. The measurements were performed at the research center for nuclear physics (RCNP) in Osaka, Japan, using the magnetic spectrometer Grand Raiden and the dispersive WS course. The 3He beam with an energy of 420 MeV was accelerated by the RCNP Ring Cyclotron. The Grand Raiden spectrometer and the WS course allow to study the (3He,t) charge-exchange reaction with an energy resolution of around 30 keV, which is one order of magnitude better than measurements with the (p,n) charge-exchange reaction. The high resolution allows to better separate individual states and to determine weak excitation strengths because of low background in the spectra. A total of 19 states in 13N were studied, and a total of 20 states were observed in 9B. Of these, 9 states in 13C and 10 states in 9B were identified as being excited by a Gamow-Teller transition. Charge-exchange reactions are related to beta-decay, and at zero momentum transfer a simple proportionality exists between the cross-section of the charge-exchange experiment and the Fermi (F) or Gamow-Teller (GT) beta-decay strength. While the Fermi strength B(F) is concentrated in the transition to the isobaric analog state, the Gamow-Teller strength B(GT) is scattered among the excited states. The main aim of the present study is to determine the B(GT) strengths in the nuclei 9B and 13N. The only charge-exchange study of 9B was made 30 years ago with the (p,n) reaction and a resolution of around 300-400 keV. Many states, especially at high excitation energy, could not be resolved by that study. The present work was able to separate many weakly excited states with small decay width at high excitation energies (12-19 MeV) in 9B and determine the B(GT) strength distribution by using recent high-precision beta-decay data. The results point to a strong difference in spatial structure between the low-lying levels of

  12. High-resolution study of the Gamow-Teller strength distribution in the light nuclei {sup 9}B and {sup 13}N using the ({sup 3}He,t) charge-exchange reaction at 420 MeV beam energy

    Energy Technology Data Exchange (ETDEWEB)

    Scholl, Clemens

    2010-07-07

    Excited states in the light nuclei {sup 9}B and {sup 13}C were studied using the ({sup 3}He,t) charge-exchange reaction on {sup 9}Be and {sup 13}C targets. The measurements were performed at the research center for nuclear physics (RCNP) in Osaka, Japan, using the magnetic spectrometer Grand Raiden and the dispersive WS course. The {sup 3}He beam with an energy of 420 MeV was accelerated by the RCNP Ring Cyclotron. The Grand Raiden spectrometer and the WS course allow to study the ({sup 3}He,t) charge-exchange reaction with an energy resolution of around 30 keV, which is one order of magnitude better than measurements with the (p,n) charge-exchange reaction. The high resolution allows to better separate individual states and to determine weak excitation strengths because of low background in the spectra. A total of 19 states in {sup 13}N were studied, and a total of 20 states were observed in {sup 9}B. Of these, 9 states in {sup 13}C and 10 states in {sup 9}B were identified as being excited by a Gamow-Teller transition. Charge-exchange reactions are related to beta-decay, and at zero momentum transfer a simple proportionality exists between the cross-section of the charge-exchange experiment and the Fermi (F) or Gamow-Teller (GT) beta-decay strength. While the Fermi strength B(F) is concentrated in the transition to the isobaric analog state, the Gamow-Teller strength B(GT) is scattered among the excited states. The main aim of the present study is to determine the B(GT) strengths in the nuclei {sup 9}B and {sup 13}N. The only charge-exchange study of {sup 9}B was made 30 years ago with the (p,n) reaction and a resolution of around 300-400 keV. Many states, especially at high excitation energy, could not be resolved by that study. The present work was able to separate many weakly excited states with small decay width at high excitation energies (12-19 MeV) in {sup 9}B and determine the B(GT) strength distribution by using recent high-precision beta-decay data. The

  13. Charge exchange between singly ionized helium ions

    International Nuclear Information System (INIS)

    The plane-wave Born approximation was used to evaluate the charge transfer cross sections for the reaction He+ + He+ → He++ + He. The charge transfer cross section is graphed as a function of incident energy and compared with experimental measurements

  14. Charge exchange between hydrogen atoms and fully stripped heavy ions

    International Nuclear Information System (INIS)

    Charge exchange between multicharged ions and background atomic and molecular gases represents one of the limitations to the attainment of high charge states in heavy ion sources, particularly containment sources. An attempt is made to study systematically a particularly simple but in many respects representative class of such reactions, namely charge transfer between atomic hydrogen and fully stripped heavy ions. Approximate cross sections for these processes in the low keV range of collision energies were obtained using a multistate Landau--Zener method. The energy and Z dependences of the cross sections are discussed

  15. Some Aspects of Electron-Exchange Reactions in Solution

    International Nuclear Information System (INIS)

    Most theories of electron exchange reactions are based upon the Franck-Condon principle. This principle requires that the inner co-ordination shells of the reactants and the polarization of the surrounding medium rearrange to some intermediate nonequilibrium configuration before the electron transfer takes place. The calculation of this reorganization requires a knowledge of such properties of the reactants as force constants, interatomic distances, etc. Unfortunately all these quantities are not known for any electron exchange reactions of interest and consequently an a priori calculation of exchange rates cannot be made with confidence at the present time. However, R. A. Marcus has shown that the rates of exchange reactions (ΔG° = 0) can be readily related to the rates of electron-transfer reactions which are accompanied by a net chemical change (ΔG° < 0). Experimental evidence bearing on the Marcus predictions are summarized. Exchange reactions between ions of like charge are often catalysed by oppositely charged ions. Important information about the nature of this catalysis can be obtained if the substitution rates are slower than, or comparable to, the electron-transfer rates. This approach has recently been used to study the effect of anions on exchange reactions between substitution labile cations. Some recent results of these studies are discussed. (author)

  16. Pion double charge exchange and nuclear structure

    International Nuclear Information System (INIS)

    Pion double charge exchange to both the double-analog state and the ground state is studied for medium weight nuclei. The relative cross section of these two transitions and the importance of nuclear structure as a function of pion kinetic energy is examined. 16 figs., 5 tabs

  17. Elastic and charge exchange scattering of pions from 3He

    International Nuclear Information System (INIS)

    Elastic and charge exchange scatterings of pions from 3He are studied using on optical potential in the momentum representation, which includes the second order effect as well as the nucleon binding correction. These corrections are found to be appreaciable but still not enough to resolve the discrepancy between theoretical calculations and recent experimental data on the reaction 3He(π-, π0)3H. (author)

  18. Charge exchange in solar wind - coometary interactions

    International Nuclear Information System (INIS)

    The authors examine the effect of charge exchange between fast solar wind ions and slow cometary neutrals at the contact discontinuity separating the ionosphere of a comet from the solar wind flow. The continuity equations were solved analytically for a water-dominated cometary ionosphere, including both ionization and recombination processes. It was found that this new solution differs significantly from the one obtained by neglecting recombination. (author)

  19. Dissociative charge exchange of H2+

    International Nuclear Information System (INIS)

    This thesis is devoted to molecular dissociation, in particular the dissociation of the hydrogen molecule H2 arising from electron capture of its ion H2+ in a collision. Thereby the important practical question how a chemical bond can be broken is implicitly addressed. This thesis opens (chapter I) with an overview of the available experimental approaches in molecular physics. Further the simple Demkov model for NRCE is described. In chapter II a novel experimental technique for measurements on dissociative processes is introduced which combines a high efficiency with a high energy resolution. A detailed description of the techniques applied in the detector, which has a high spatial and timing resolution with 30 μm and 350 psec FWHM respectively for the detection of one particle, is given in chapter III. A semi-classical theory for NRCE in the medium energy range between a diatomic molecular ion and an atom is developed in chapter IV. The experiments on dissociative charge exchange of H2+ with Ar, Mg, Na and Cs targets at keV energies are described in Chapter V. The predissociation of the c3PIsub(u)-state of H2 populated after charge exchange of H2 with several targets at keV energies; is the subject of chapter VI. In chapter VII, orientational oscillations in the cross section for charge exchange of H2+ with alkali targets are discussed. The last chapter deals with predissociation of highly excited states in H2. (Auth.)

  20. Study of the elastic scattering and of the (p,n) charge exchange reaction with neutron-rich light exotic beams; Etude de la diffusion elastique et de la reaction d`echange de charge (p,n) avec des faisceaux exotiques legers riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D.

    1996-07-05

    We have measured at GANIL, with the high resolution spectrometer SPEG, the elastic scattering of several neutron rich secondary beams ({sup 6}He, {sup 10}Be and {sup 11}Be) on a polypropylene target and the charge exchange reaction p({sup 6}He, {sup 6}Li)n. These exotic beams were produced by nuclear fragmentation and re-focalized with the SISSI device (superconducting solenoids). The signature of a halo structure in these nuclei has been analysed. Special attention has been paid to several aspects of the associated calculations namely, the proton and neutron density distributions and the small binding energy for the last nucleons in these exotic nuclei. Break-up mechanisms are seen to play an important role in these nuclei. 100 refs.

  1. Anatomy of charge-exchange straggling

    International Nuclear Information System (INIS)

    We have studied charge-exchange straggling theoretically for swift krypton and silicon ions and five target gases in the MeV/u energy regime. We find a pronounced two-peak structure for all ion-target combinations. The peak at the highest energy appears around the velocity where the bare ion and the one-electron ion are equally abundant in the equilibrium charge distribution. Correspondingly, the low-energy peak appears near the cross-over between the charge fractions of the two- and the three-electron ion. The possibility of further peaks at lower energies is discussed. Our findings are compared with recent experimental results on straggling of krypton beams

  2. Anatomy of charge-exchange straggling

    Energy Technology Data Exchange (ETDEWEB)

    Sigmund, P., E-mail: sigmund@sdu.dk [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Osmani, O. [Department of Physics, University of Duisburg-Essen, D-47048 Duisburg (Germany); Schinner, A. [Institut für Experimentalphysik, Johannes Kepler Universität, A-4040 Linz (Austria)

    2014-11-01

    We have studied charge-exchange straggling theoretically for swift krypton and silicon ions and five target gases in the MeV/u energy regime. We find a pronounced two-peak structure for all ion-target combinations. The peak at the highest energy appears around the velocity where the bare ion and the one-electron ion are equally abundant in the equilibrium charge distribution. Correspondingly, the low-energy peak appears near the cross-over between the charge fractions of the two- and the three-electron ion. The possibility of further peaks at lower energies is discussed. Our findings are compared with recent experimental results on straggling of krypton beams.

  3. Production of antihydrogen via double charge exchange

    International Nuclear Information System (INIS)

    Spectroscopy of the 1S-2S transition of antihydrogen confined in a neutral atom trap and comparison with the equivalent spectral line in hydrogen will provide an accurate test of CPT symmetry and the first one in a mixed baryon-lepton system. Also, with neutral antihydrogen atoms, the gravitational interaction between matter and antimatter can be tested unperturbed by the much stronger Coulomb forces. Antihydrogen is regularly produced at CERN's Antiproton Decelerator by three-body-recombination (TBR) of one antiproton and two positrons. The method requires injecting antiprotons into a cloud of positrons, which raises the average temperature of the antihydrogen atoms produced way above the typical 0.5 K trap depths of neutral atom traps. Therefore only very few antihydrogen atoms can be confined at a time. Precision measurements, like laser spectroscopy, will greatly benefit from larger numbers of simultaneously trapped antihydrogen atoms. Therefore, the ATRAP collaboration developed a different production method that has the potential to create much larger numbers of cold, trappable antihydrogen atoms. Positrons and antiprotons are stored and cooled in a Penning trap in close proximity. Laser excited cesium atoms collide with the positrons, forming Rydberg positronium, a bound state of an electron and a positron. The positronium atoms are no longer confined by the electric potentials of the Penning trap and some drift into the neighboring cloud of antiprotons where, in a second charge exchange collision, they form antihydrogen. The antiprotons remain at rest during the entire process, so much larger numbers of trappable antihydrogen atoms can be produced. Laser excitation is necessary to increase the efficiency of the process since the cross sections for charge-exchange collisions scale with the fourth power of the principal quantum number n. This method, named double charge-exchange, was demonstrated by ATRAP in 2004. Since then, ATRAP constructed a new combined

  4. Improved pellet charge exchange measurements in Large Helical Device

    International Nuclear Information System (INIS)

    The pellet charge exchange technique (PCX), which is a combination of the compact neutral particle analyzer and an impurity pellet, is a unique method to observe the radial energetic particle distribution. There are not only charge exchange reactions between the hydrogen in the pellet and a proton, but also between the partially ionized carbon in the pellet and the proton. The neutralization factor from energetic ion to neutral particle could be deduced from the electron temperature and the electron density of the pellet cloud. The radial profiles of energetic particle distribution were measured and compared in various ion cyclotron resonance heating (ICH) plasmas. The energetic particle flux significantly increased at the resonance layer created by the ICH. PCX provides more precise information about the resonance layer than conventional neutral particle diagnostics. (author)

  5. Exchange effects in direct reactions

    International Nuclear Information System (INIS)

    The effect of antisymmetrization in direct reactions is examined by studying the properties of the coupling-normalization kernel function occurring in a resonating-group formulation. From this study, one obtains useful information concerning the general behavior of direct-reactiion processes and some justification for the use of three-body models in phenomenological analyses

  6. Strangeness exchange reactions and hypernuclei

    International Nuclear Information System (INIS)

    Recent progress in the spectroscopy of Λ and Σ hypernuclei is reviewed. Prospects for the production of doubly strange hypernuclei at a future kaon factory are assessed. It is suggested that the (K-,K+) reaction on a nuclear target may afford an optimal way of producing the H dibaryon, a stable six quark object with J/sup π/ = O+, S = -2

  7. Charge exchange cross section database for proton collisions with hydrocarbon molecules

    International Nuclear Information System (INIS)

    The available experimental and theoretical cross section data on charge exchange processes in collisions of protons with hydrocarbon molecules have been collected and critically assessed. Using well established scaling relationships for the charge exchange cross sections at low and high collision energies, as well as the known rate coefficients for these reactions in the thermal energy region, a complete cross sections database is constructed for proton-CxHy charge exchange reactions from thermal energies up to several hundreds keV for all CxHy molecules with x=1,2,3 and 1≤y≤2x+2. (author)

  8. μ+ charge exchange and muonium formation in low pressure gases

    International Nuclear Information System (INIS)

    Using the basic muon spin rotation technique, the fractions of energetic positive muons thermalizing in diamagnetic environments (fsub(μ)) or as the paramagnetic muonium atom (fsub(Mu)) have been measured in low pressure pure gases (He, Ne, Ar, Kr, Xe, H2, N2, NH3, and CH4) as well as in several gas mixtures (Ne/Xe, Ne/Ar, Ne/NH3, Ne/CH4). In the pure gases, the muonium fractions fsub(Mu) are generally found to be smaller than expected from analogous proton charge exchange studies, particularly in the molecular gases. This is probably due to hot atom reactions of muonium following the charge exchange regime. Comparisons with monium formation in condensed matter as well as positronium formation in gases are also presented. In the gas mixtures, the addition of only a few hundred ppm of a dopant gas, which is exothermic for muonium formation (e.g. Xe), gives rise to an fsub(Mu) characteristic of the pure dopant gas itself, demonstrating the importance of the neutralization process right down to thermal energies. In all cases, the experimental signal amplitudes are found to be strongly pressure dependent, which is interpreted in terms of the time spent by the muon as neutral muonium in the charge exchange regime: tsub(n) < 0.2 ns. This time is generally shorter in the case of molecular gases than in rare gases

  9. Charge exchange recombination x-ray laser

    International Nuclear Information System (INIS)

    A recombining plasma x-ray laser using charge exchange recombination (CXR) is proposed. Fully stripped carbon ions collide with neutral He atoms and become excited hydrogenlike carbon ions, in which the excited levels with n=3 or 4 are mainly populated. We calculate the gain coefficients of the Balmer α and the Lyman β line of the hydrogenlike carbon ions by the use of a collisional-radiative model in which the CXR process is included. The calculated result shows that substantial gain can be generated for the Lyman β and Balmer α lines and that the gain of the Balmer α line can be strongly enhanced by the effect of CXR. We also report a preliminary experiment of this scheme. (author)

  10. Intermediates in Isotopic Exchange Reactions Involving Diborane

    International Nuclear Information System (INIS)

    By conventional mass spectrometric analysis, the self-exchange reaction of diborane was studied by using boron and hydrogen isotopes as tracers. The ratio of deuterium to boron exchange was found to be 2.8. This suggests that the reaction is not completely proceeding by exchange of BH3's as an entity, and that the mechanism is more complicated than simply a stripping reaction between diborane and a borane. It was therefore decided to attempt to get some knowledge of the intermediates that are present in diborane dissociation since they may shed light on the mechanism of the exchange. Using a specially constructed mass spectrometer of high sensitivity coupled with a flow reactor, it was possible to make a direct detection of the intermediate involved in the diborane equilibria. The intermediates BH3 and BH2 were found to be present and their ionization potentials were measured. In addition, a small amount of B3Hn was observed but the value of n could not be determined because of the weak peaks obtained. An attempt is made to interpret the self-exchange reaction of diborane in terms of these intermediates. The results suggest that diborane is in rapid equilibrium with borane (BH3). In addition, apparently diborane can also dissociate in BH2 which was about twice as abundant as BH3. The B3Hn intermediate that was observed is believed to arise from the reaction. BH3 + B2H6 -> B3H9. In applying this information to the isotopic self-exchange in diborane, it appears that the exchange cannot be going by a stripping mechanism such as BD3 + BH3 - BH3 - BD3 - BH3 + BH3, since the deuterium-to-boron isotopic ratio then should be 3. Another possible mechanism of exchange is BD3 + B2H6 ⇌ B3D3H6; the B3 complex can be pictured as a symmetrical one. If the bonds were all exactly equivalent the D/ 10B ratio would statistically become 3; however, some isotope effect may be present in the fragmentation of the complex and the ratio could deviate from 3. Another possible way in which

  11. Fine structure of charge exchange lines observed in laboratory plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ida, K.; Nishimura, S. [National Inst. for Fusion Science, Nagoya (Japan); Kondo, K.

    1997-01-01

    The influence of the fine structure of charge exchange lines appears only at the plasma edge or in the recombining phase where the ion temperature is low enough. The observed spectra in Li III and C VI are consistent with the sum of fine-structure components populated by statistical weights (assuming complete l-mixing) not by direct charge exchange cross sections. Some discrepancy was observed in the intensity ratio of fine-structure components between the observation and calculation for C VI in the recombining phase. The fine-structure of charge exchange lines gives an apparent Doppler shift in plasma rotation velocity measurement using charge exchange spectroscopy. (author)

  12. Charge Exchange Collisions between Ultracold Fermionic Lithium Atoms and Calcium Ions

    CERN Document Server

    Haze, Shinsuke; Saito, Ryoichi; Mukaiyama, Takashi

    2014-01-01

    An observation of charge exchange collisions between ultracold fermionic 6Li atoms and 40Ca+ ions is reported. The reaction product of the charge exchange collision is dentified via mass spectrometry where the motion of the ions is excited parametrically. We measure the cross section of the charge exchange collisions between the 6Li atoms in the ground state and the 40Ca+ ions in the ground and metastable excited states. Investigation of the inelastic collision characteristics in the atom-ion mixture is an important step toward ultracold chemistry based on ultracold atoms and ions.

  13. Suzaku Observations of Charge Exchange Emission from Solar System Objects

    Science.gov (United States)

    Ezoe, Y.; Fujimoto, R.; Yamasaki, N. Y.; Mitsuda, K.; Ohashi, T.; Ishikawa, K.; Oishi, S.; Miyoshi, Y; Terada, N.; Futaana, Y.; Porter, F. S.; Brown, G. V.

    2012-01-01

    Recent results of charge exchange emission from solar system objects observed with the Japanese Suzaku satellite are reviewed. Suzaku is of great importance to investigate diffuse X-ray emission like the charge exchange from planetary exospheres and comets. The Suzaku studies of Earth's exosphere, Martian exosphere, Jupiter's aurorae, and comets are overviewed.

  14. Laboratory simulation of charge exchange-produced X-ray emission from comets.

    Science.gov (United States)

    Beiersdorfer, P; Boyce, K R; Brown, G V; Chen, H; Kahn, S M; Kelley, R L; May, M; Olson, R E; Porter, F S; Stahle, C K; Tillotson, W A

    2003-06-01

    In laboratory experiments using the engineering spare microcalorimeter detector from the ASTRO-E satellite mission, we recorded the x-ray emission of highly charged ions of carbon, nitrogen, and oxygen, which simulates charge exchange reactions between heavy ions in the solar wind and neutral gases in cometary comae. The spectra are complex and do not readily match predictions. We developed a charge exchange emission model that successfully reproduces the soft x-ray spectrum of comet Linear C/1999 S4, observed with the Chandra X-ray Observatory. PMID:12791989

  15. X-ray emission from charge exchange of highly-charged ions in atoms and molecules

    Science.gov (United States)

    Greenwood, J. B.; Williams, I. D.; Smith, S. J.; Chutjian, A.

    2000-01-01

    Charge exchange followed by radiative stabilization are the main processes responsible for the recent observations of X-ray emission from comets in their approach to the Sun. A new apparatus was constructed to measure, in collisions of HCIs with atoms and molecules, (a) absolute cross sections for single and multiple charge exchange, and (b) normalized X-ray emission cross sections.

  16. Nuclear isovector giant resonances excited by pion single charge exchange

    International Nuclear Information System (INIS)

    This thesis is an experimental study of isovector giant resonances in light nuclei excited by pion single charge exchange reactions. Giant dipole resonances in light nuclei are known to be highly structured. For the mass 9 and 13 giant dipole resonances, isospin considerations were found to be very important to understanding this structure. by comparing the excitation functions from cross section measurements of the (π+, π0) and (π, π0) inclusive reactions, the authors determined the dominant isospin structure of the analog IVGR's. The comparison was made after decomposing the cross section into resonant and non-resonant components. This decomposition is made in the framework of strong absorption and quasi-free scattering. Measurements in the region of the isovector giant dipole resonances (IVGDR) were made to cover the inclusive angular distributions out to the second minimum. Study of the giant resonance decay process provides further understanding of the resonances. This study was carried out by observing the (π+, π0p) coincident reactions involving the resonances of 9B and 13N excited from 9Be and 13C nuclei. These measurements determined the spectra of the decay protons. This method also permitted a decomposition of the giant resonances into their isospin components. The multipolarities of the resonances were revealed by the decay proton angular correlations which, for dipoles, are of the form 1 + A2P2(cos θ)

  17. Proceedings of the LAMPF workshop on pion double charge exchange

    International Nuclear Information System (INIS)

    Experimental and theoretical aspects of double-analog, nonanalog, and continuum pion double charge exchange in the 50- to 310-MeV energy range are covered. Separate abstracts were prepared for 22 papers in these proceedings

  18. Asymmetric H-D exchange reactions of fluorinated aromatic ketones

    KAUST Repository

    Zhao, Yujun

    2012-01-01

    Chiral bicyclic guanidine catalyzes the asymmetric H-D exchange reactions. Up to 30% ee was achieved. DFT calculations were employed to elucidate and explain the origin of the reaction\\'s stereoselectivity. © 2012 The Royal Society of Chemistry.

  19. Ion momentum and energy transfer rates for charge exchange collisions

    Science.gov (United States)

    Horwitz, J.; Banks, P. M.

    1973-01-01

    The rates of momentum and energy transfer have been obtained for charge exchange collisions between ion and neutral gases having arbitrary Maxwellian temperatures and bulk transport velocities. The results are directly applicable to the F-region of the ionosphere where 0+ - 0 charge is the dominant mechanism affecting ion momentum and energy transfer.

  20. Charge exchange emission from solar wind helium ions

    NARCIS (Netherlands)

    Bodewits, D; Hoekstra, R; Seredyuk, B; McCullough, RW; Jones, GH; Tielens, AGGM

    2006-01-01

    Charge exchange X-ray and far-ultraviolet (FUV) aurorae can provide detailed insight into the interaction between solar system plasmas. Using the two complementary experimental techniques of photon emission spectroscopy and translation energy spectroscopy, we have studied state-selective charge exch

  1. Inclusive double-charge-exchange π- production at 100 GeV/c

    International Nuclear Information System (INIS)

    Measurements of inclusive cross sections at 100 GeV/c are presented for the double-charge-exchange reactions a+p → π-X with a = π, K, or p. The measurements covered a kinematic range in the Feynman x variable of 0.3 - production is used to fit the data and demonstrates the importance of resonance production via one-pion exchange for large values of the Feynman x

  2. Antiproton small momentum transfer charge exchange scattering on protons at 30 GeV/c

    International Nuclear Information System (INIS)

    Antiproton charge exchange scattering on protons anti pp→anti nn is investigated with 30 GeV/c antiprotons at the IHEP accelerator. The experiment confirms the existence of a structure at small angles in the angular distribution of this reaction at high energies, observed earlier

  3. Charge exchange of a polar molecule at its cation

    International Nuclear Information System (INIS)

    The Landau-Herring method is used to derive an analytic expression for the one-electron exchange interaction of a polar molecule with its positively charged ion, induced by a σ-electron. Analogously to the classical Van der Pole method, the exchange interaction potential is averaged over the rotational states of colliding particles. The resonant charge-transfer cross section is calculated, and the effect of the dipole moments of the core on the cross section is analyzed. It is shown that allowance for the dependence of the exchange potential on the orientation of the dipole moments relative to the molecular axis may change the dependence of the cross section on the velocity of colliding particles, which is typical of the resonant charge exchange, from the resonance to the quasi-resonance dependence.

  4. Charge exchange X-rays from the heliosheath

    Science.gov (United States)

    Medvedev, M. V.; Robertson, I. P.; Cravens, T. E.; Zank, G. P.; Florinski, V.

    2006-09-01

    X-rays are produced throughout the heliosphere as a consequence of charge transfer collisions between heavy solar wind ions and neutral atoms. After such a collision the solar wind ion is left in a highly excited state and emits extreme ultraviolet and soft X-ray photons. In the outer heliosphere, solar wind charge exchange X-ray emission is mainly due to charge exchange with neutral interstellar hydrogen. We have combined MHD simulations with a comprehensive charge exchange computation code. We trace the full evolution of solar wind ions along stream line in order to produce three-dimensional emissivities and, subsequently, two-dimensional X-ray brightness and spectral maps of the heliosphere as would be observed from the outside. The model treats both the collisionally thin and the collisionally thick regimes. This model can be a diagnostic tool for studying stellar wind properties of nearby Sun-like stars.

  5. Charge density path in cold fusion reactions

    International Nuclear Information System (INIS)

    Cold fusion reactions are very frequently employed to produce compound nuclei with a relatively low excitation energy, which is extremely important for a successful synthesis method, particularly in the region of superheavy nuclei. Usually the charge densities of the projectile, target, and compound nucleus are different. We present a method allowing to take into consideration this difference continuously during the fusion process. Applications are given both in the intermediate mass and the superheavy region. Different cold fusion paths are studied with respect to the change of the charge density within the overlapping region. A transition formula from separated fusion partners up to the compound nucleus is obtained as depending on the geometrical changes. Macroscopic-microscopic approach is used to compute the total deformation energy. Shell corrections are obtained with Strutinsky method, having the new deformed two-center single particle energy levels as an input. Yukawa-plus-exponential model is employed to compute the macroscopic part. Spheroidal deformations are taken into account. By changing the absolute value of semiaxes as well as their ratio, the charge densities of the partners are modified during fusion. As a result of minimization against different paths of the semiaxes ratios from projectile and target values to synthesized nucleus, charge density variation can lower the cold fusion deformation energy. This kind of influence is especially active in the last part of the fusion process, when the projectile is already at least half embedded in the target. For cold fusion of light and intermediate nuclei, the energy variation in the last part of the deformation path reaches 4 MeV for 102 Ru and 3.7 MeV for 152 Dy synthesis. For a possible superheavy production the influence of charge density changes are quantitatively more important. The energy difference in the cold fusion channel barrier of 292 116 reaches about 8 MeV in the last part of the

  6. Radiation reaction for a massless charged particle

    Energy Technology Data Exchange (ETDEWEB)

    Kazinski, P O; Sharapov, A A [Physics Faculty, Tomsk State University, Tomsk, 634050 (Russian Federation)

    2003-07-07

    We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field with regard to the radiation back reaction. It is shown that unlike the massive case, not all the divergences resulting from the self-action of the particle are Lagrangian, i.e., can be cancelled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of a homogeneous external field, the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure.

  7. Radiation reaction for a massless charged particle

    CERN Document Server

    Kazinski, P O

    2003-01-01

    We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field having regard to the radiation back reaction. It is shown that unlike the massive case not all the divergences resulting from the self-action of the particle are Lagrangian, i.e. can be canceled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of homogeneous external field the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure.

  8. Radiation reaction for a massless charged particle

    International Nuclear Information System (INIS)

    We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field with regard to the radiation back reaction. It is shown that unlike the massive case, not all the divergences resulting from the self-action of the particle are Lagrangian, i.e., can be cancelled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of a homogeneous external field, the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure

  9. Radiation reaction for a massless charged particle

    Science.gov (United States)

    Kazinski, P. O.; Sharapov, A. A.

    2003-07-01

    We derive effective equations of motion for a massless charged particle coupled to the dynamical electromagnetic field with regard to the radiation back reaction. It is shown that unlike the massive case, not all the divergences resulting from the self-action of the particle are Lagrangian, i.e., can be cancelled out by adding appropriate counterterms to the original action. Besides, the order of renormalized differential equations governing the effective dynamics turns out to be greater than the order of the corresponding Lorentz-Dirac equation for a massive particle. For the case of a homogeneous external field, the first radiative correction to the Lorentz equation is explicitly derived via the reduction of order procedure.

  10. Computational Approach to Electron Charge Transfer Reactions

    DEFF Research Database (Denmark)

    Jónsson, Elvar Örn

    The step from ab initio atomic and molecular properties to thermodynamic - or macroscopic - properties requires the combination of several theoretical tools. This dissertation presents constant temperature molecular dynamics with bond length constraints, a hybrid quantum mechanics...... show general (or expected) properties. Properties such as in the physical and (semi-)chemical interface between classical and quantum systems and the effects of molecular bond length constraints on the temperature during simulations. As a second step the methodology is applied to the symmetric and...... asymmetric charge transfer reactions between several first-row transition metals in water. The results are compared to experiments and rationalised with classical analytic expressions. Shortcomings of the methods are accounted for with clear steps towards improved accuracy. Later the analysis is extended to...

  11. Charge transfer reaction laser with preionization means

    Science.gov (United States)

    Lauderslager, J. B.; Pacala, T. J. (Inventor)

    1978-01-01

    A helium-nitrogen laser is described in which energy in the visible range is emitted as a result of charge transfer reaction between helium ions and nitrogen molecules. The helium and nitrogen are present in a gas mixture at several atmospheres pressure, with a nitrogen partial pressure on the order of a pair of main discharge electrodes, the gas mixture is preionized to prevent arcing when the discharge pulse is applied. The preionization is achieved by the application of a high voltage across a pair of secondary electrodes which are spaced apart in a direction perpendicular to the spacing direction of the main discharge electrodes and the longitudinal axis of the space in which the gas mixture is contained. Feedback, by means of a pair of appropriately spaced mirrors, is provided, to produce coherent energy pulses at a selected wavelength.

  12. Dressed Charge of Electron by Radiation Reaction

    Science.gov (United States)

    SETO, Keita; Zhang, Sen; KOGA, James; Moritaka, Toseo; Homma, Kensuke; Nakamiya, Yoshihide; NAGATOMO, Hideo; MIMA, Kunioki

    2016-03-01

    With the progress of ultraintense short pulse laser technologies, the maximum intensity of the lasers has reached the order of 1022W/cm2. Now, several institutes are aiming at higher intensities of over 1024∼W/cm2. It is expected that these lasers can investigate the regime of the ultra-intense field effects like electron-positron pair creation and annihilation, these high-intense laser fields enters into the non-linear QED regime. However, when an electron interacts with lasers with intensities over 1022W/cm2, it has been predicted that the radiation reaction effect becomes significant. The strong radiation field can induce the fluctuation of QED vacuum (vacuum polarization or photon-photon scatterings). Though the propagator for fields is deformed by it, some kind of a polarized charge exists as the dress. In this paper, we will discuss about this dress of an electron generated by radiation in the description of classical physics. It leads to the avoidance of the mathematical difficulty of the radiation reaction problems.

  13. A charge exchange chamber with built-in focusing

    International Nuclear Information System (INIS)

    This invention concerns a charge exchange chamber with built-in focusing enabling a beam of low divergence neutrals to be obtained from a beam of ions of a given energy. The ion beam enters the charge exchange chamber filled with a neutral gas under pressure, the effect of which is an exchange of charges between the ions and the neutral molecules or atoms of the gas. The positive ions are substantially sent along the axis of the enclosure, characterised in that it includes electric facilities for concentrating the ions of the beam near this axis. These electric facilities are composed of a series of grids perpendicular to the direction of the ion jet, grids that are transparent and of negative potential and the potential of each of these grids increases in absolute value along the path of the ion jet in the enclosure

  14. ({sup 18}O,{sup 18}Ne) double charge-exchange with MAGNEX

    Energy Technology Data Exchange (ETDEWEB)

    Bondí, M.; Cappuzzello, F.; Nicolosi, D.; Tropea, S. [Dipartimento di Fisica e Astrofisica, Universitá degli studi di Catania, Catania, 95100, Italy and Istituto di Fisica Nucleare - Laboratori Nazionali del Sud, Catania, 95100 (Italy); Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A. [Istituto di Fisica Nucleare - Laboratori Nazionali del Sud, Catania, 95100 (Italy); De Napoli, M.; Foti, A. [Istituto di Fisica Nucleare - Sezione di Catania, Catania, 95100 (Italy)

    2014-05-09

    An experimental study concerning Double Gamow-Teller (DGT) modes in ({sup 18}O,{sup 18}Ne) Double Charge-Exchange reactions has been very recently performed at INFN-LNS laboratory in Catania. The experiment was performed using a {sup 40}Ca solid target and a {sup 18}O Cyclotron beam at 270 MeV incident energy. Charged ejectiles produced in the reaction were momentum analyzed and identified by MAGNEX spectrometer at very forward angles. Preliminary results are presented in the present paper.

  15. Charge-dependent many-body exchange and dispersion interactions in combined QM/MM simulations

    International Nuclear Information System (INIS)

    Accurate modeling of the molecular environment is critical in condensed phase simulations of chemical reactions. Conventional quantum mechanical/molecular mechanical (QM/MM) simulations traditionally model non-electrostatic non-bonded interactions through an empirical Lennard-Jones (LJ) potential which, in violation of intuitive chemical principles, is bereft of any explicit coupling to an atom’s local electronic structure. This oversight results in a model whereby short-ranged exchange-repulsion and long-ranged dispersion interactions are invariant to changes in the local atomic charge, leading to accuracy limitations for chemical reactions where significant atomic charge transfer can occur along the reaction coordinate. The present work presents a variational, charge-dependent exchange-repulsion and dispersion model, referred to as the charge-dependent exchange and dispersion (QXD) model, for hybrid QM/MM simulations. Analytic expressions for the energy and gradients are provided, as well as a description of the integration of the model into existing QM/MM frameworks, allowing QXD to replace traditional LJ interactions in simulations of reactive condensed phase systems. After initial validation against QM data, the method is demonstrated by capturing the solvation free energies of a series of small, chlorine-containing compounds that have varying charge on the chlorine atom. The model is further tested on the SN2 attack of a chloride anion on methylchloride. Results suggest that the QXD model, unlike the traditional LJ model, is able to simultaneously obtain accurate solvation free energies for a range of compounds while at the same time closely reproducing the experimental reaction free energy barrier. The QXD interaction model allows explicit coupling of atomic charge with many-body exchange and dispersion interactions that are related to atomic size and provides a more accurate and robust representation of non-electrostatic non-bonded QM/MM interactions

  16. Charge-dependent many-body exchange and dispersion interactions in combined QM/MM simulations

    Energy Technology Data Exchange (ETDEWEB)

    Kuechler, Erich R. [BioMaPS Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854-8087 (United States); Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431 (United States); Giese, Timothy J.; York, Darrin M. [BioMaPS Institute and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854-8087 (United States)

    2015-12-21

    Accurate modeling of the molecular environment is critical in condensed phase simulations of chemical reactions. Conventional quantum mechanical/molecular mechanical (QM/MM) simulations traditionally model non-electrostatic non-bonded interactions through an empirical Lennard-Jones (LJ) potential which, in violation of intuitive chemical principles, is bereft of any explicit coupling to an atom’s local electronic structure. This oversight results in a model whereby short-ranged exchange-repulsion and long-ranged dispersion interactions are invariant to changes in the local atomic charge, leading to accuracy limitations for chemical reactions where significant atomic charge transfer can occur along the reaction coordinate. The present work presents a variational, charge-dependent exchange-repulsion and dispersion model, referred to as the charge-dependent exchange and dispersion (QXD) model, for hybrid QM/MM simulations. Analytic expressions for the energy and gradients are provided, as well as a description of the integration of the model into existing QM/MM frameworks, allowing QXD to replace traditional LJ interactions in simulations of reactive condensed phase systems. After initial validation against QM data, the method is demonstrated by capturing the solvation free energies of a series of small, chlorine-containing compounds that have varying charge on the chlorine atom. The model is further tested on the S{sub N}2 attack of a chloride anion on methylchloride. Results suggest that the QXD model, unlike the traditional LJ model, is able to simultaneously obtain accurate solvation free energies for a range of compounds while at the same time closely reproducing the experimental reaction free energy barrier. The QXD interaction model allows explicit coupling of atomic charge with many-body exchange and dispersion interactions that are related to atomic size and provides a more accurate and robust representation of non-electrostatic non-bonded QM

  17. Charge Exchange Spectra of Hydrogenic and He-like Iron

    CERN Document Server

    Wargelin, B J; Neill, P A; Olson, R E; Scofield, J H

    2005-01-01

    We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra resulting from collisions of highly charged iron with N2 gas at an energy of 10 eV/amu in an electron beam ion trap. Although individual high-n emission lines are not resolved in our measurements, we observe that the most likely level for Fe25+ --> Fe24+ electron capture is n~9, in line with expectations, while the most likely value for Fe26+ --> Fe25+ charge exchange is significantly higher. In the Fe XXV spectrum, the K-alpha emission feature dominates, whether produced via charge exchange or collisional excitation. The K-alpha centroid is lower in energy for the former case than the latter (6666 versus 6685 eV, respectively), as expected because of the strong enhancement of emission from the forbidden and intercombination lines, relative to the resonance line, in charge-exchange spectra. In contrast, the Fe XXVI high-n Lyman lines have a summed intensity greater than that of Ly-alpha, and are substantially stronger than predicted from the...

  18. Measurement of absorption and charge exchange of $\\pi^+$ on carbon

    CERN Document Server

    Ieki, K; Berkman, S; Bhadra, S; Cao, C; de Perio, P; Hayato, Y; Ikeda, M; Kanazawa, Y; Kim, J; Kitching, P; Mahn, K; Nakaya, T; Nicholson, M; Olchanski, K; Rettie, S; Tanaka, H A; Wilking, M J; Tobayama, S; Yamauchi, T; Yen, S; Yokoyama, M

    2015-01-01

    The combined cross section for absorption and charge exchange interactions of positively charged pions with carbon nuclei for the momentum range 200 MeV/c to 300 MeV/c have been measured with the DUET experiment at TRIUMF. The uncertainty is reduced by nearly half compared to previous experiments. This result will be a valuable input to existing models to constrain pion interactions with nuclei.

  19. Charge exchange cooling in the tandem mirror plasma confinement apparatus

    International Nuclear Information System (INIS)

    A method and apparatus are described for cooling a plasma confined in the center mirror cell of the tandem mirror apparatus by injecting cold neutral species of the plasma into at least one mirroring region of the center mirror cell. The cooling is due to the loss of warm charged species through charge exchange with the cold neutral species with resulting diffusion of the warm neutral species out of the plasma

  20. Heterogeneous Catalysis: Deuterium Exchange Reactions of Hydrogen and Methane

    Science.gov (United States)

    Mirich, Anne; Miller, Trisha Hoette; Klotz, Elsbeth; Mattson, Bruce

    2015-01-01

    Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H[subscript 2] + D[subscript 2], which proceeds at temperatures as low as 77…

  1. Electron-Exchange Reactions of Aromatic Molecules

    International Nuclear Information System (INIS)

    A large body of information is available on the rates and mechanisms of inorganic electron-exchange processes. In contrast, purely organic systems have received only minor attention. The homogeneous electron-exchange rates (kexc) and the heterogeneous rate constants for the electrode reaction (kel) have been measured only for a few hydrocarbons. We have measured kexc for a variety of aromatic systems including hydrocarbons, quinones and nitro compounds. These measurements have been carried out via electron paramagnetic resonance (EPR) line broadening measurements on mixtures of radical ions and their parent compounds. We have been able to measure kexc with a precision that allows detection of small differences presumably due to molecular structure and environment. Hydrocarbon systems like anthracene/anthracene anion are very rapid with kexc values of ca. 108-109 litres mole-1 sec-1. Some substituted aromatics like quinones and nitriles are also quite rapid. However, when a strong electron acceptor function is present like a nitro group in nitrobenzene, the value of kexc decreases by a factor of 10. It is possible to correlate changes in kexc in the nitrobenzene series with the unpaired electron density in terms of the 14N coupling constants of the EPR spectra. Further, the nitro aromatic series show very large variations in kexc with the solvent system. These changes can be correlated with recent studies of the solvation effect on hyperfine coupling constants. Marcus has reviewed recently chemical and electrochemical electron-transfer theory and suggested correlations between kexc and kel. We have measured kel especially for the nitrobenzene system under conditions which are as nearly identical experimentally to the EPR studies as possible. The electrochemical investigations were carried out by a steady-state d.c. method to eliminate some of the uncertainties inherent in electrochemical relaxation techniques. Rotated disc electrodes at low temperatures were used

  2. Electron-Exchange Reactions Mediated by Oxyanions

    International Nuclear Information System (INIS)

    Although a considerable amount of information is available on the rates of electron transfer from one metal ion to another through organic ligands (such as carboxylic acids), little has been obtained for ligands not containing carbon-carbon bonds: the one notable exception is the series of halogeno bridges. We have measured electron exchange rates between CoIII and CrII , VII, and EuII using oxyanions as bridging groups. The measurements have been carried out spectrophotometrically, using pentaamminecobalt (III) complexes in perchlorate and sulfate media. Bridging groups include metaborate, carbonate, nitrate, nitrite (both as the nitro and the nitrito ligands), sulfite, sulfate, thiosulfate, selenite, selenate, and tellurate. Specific rates increase along a series such as -OBO, -OCO-2, -ONO2, and down a series such as -OSO-3 , -OSeO-3 (k = 23 M-1sec-1 for the CrII reduction of the sulfato complex, 360 M-1 sec-1 for that of the selenato). In general, rates are more rapid with CrII as the reducing agent. Some experiments with TiIII show it to be the slowest. It appears possible to correlate changes in kbi with (i) the central atom of the ligand and (ii) the number of oxygen atoms present in the ligand but not bound to the cobalt center (that is, with the number of attack sites available to the reductant). For example, at 25°C, the specific rate for the CrH reduction of the sulfito complex is 18 M-1sec-1 and that for the sulfato is 20±2 M-1 sec1: both ligands possess three oxygens not bound to the cobalt; for the bonding in the sulfito complex is Co-S, while that in the sulfato is Co-O-S. The activation parameters for the two reactions are almost identical. Another striking example is found in the tetraammine series: the specific rate for the reaction of the chelated sulfate is 35 M-1 sec-1, while that for the chelated sulfite, is 17 M-1 sec-1. The sulfato complex possesses two oxygens free, the sulfito only one. The complexes offer the opportunity of studying

  3. Introduction of tritium into organic compounds by isotope exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    Myasoedov, N.F. (AN SSSR, Moscow (Russian Federation). Inst. Molekulyarnoj Genetiki)

    1993-05-01

    Various isotope exchange reactions for the introduction of tritium into a range of organic compounds have been investigated. The influence of the catalyst, solvent and reaction conditions on the yield and specific activities of a number of steroids, phytohormones and sugars are reported. Heterogeneous hydrogen isotope exchange with gaseous tritium has also been used to label a number of nonpolar compounds. Similarly the potential of solid state hydrogen isotope exchange has been explored. The reaction mechanism is discussed as well as the influence of the reaction conditions on the specific activity and the label distribution. (author).

  4. Introduction of tritium into organic compounds by isotope exchange reactions

    International Nuclear Information System (INIS)

    Various isotope exchange reactions for the introduction of tritium into a range of organic compounds have been investigated. The influence of the catalyst, solvent and reaction conditions on the yield and specific activities of a number of steroids, phytohormones and sugars are reported. Heterogeneous hydrogen isotope exchange with gaseous tritium has also been used to label a number of nonpolar compounds. Similarly the potential of solid state hydrogen isotope exchange has been explored. The reaction mechanism is discussed as well as the influence of the reaction conditions on the specific activity and the label distribution. (author)

  5. Charge exchange spectroscopy as a fast ion diagnostic on TEXTOR

    NARCIS (Netherlands)

    Delabie, E.; Jaspers, R. J. E.; von Hellermann, M. G.; Nielsen, S.K.; Marchuk, O.

    2008-01-01

    An upgraded charge exchange spectroscopy diagnostic has been taken into operation at the TEXTOR tokamak. The angles of the viewing lines with the toroidal magnetic field are close to the pitch angles at birth of fast ions injected by one of the neutral beam injectors. Using another neutral beam for

  6. Isotope exchange reactions in hydrogen mixtures

    International Nuclear Information System (INIS)

    The rates of isotopic exchange for the excited states of muonic hydrogen are calculated as functions of collision energy. Ground state population q1s for different collision energies, target densities and isotope concentrations is obtained. It is shown that for principal quantum numbers n > 5 the isotopic exchange still considerably influences the value of q1s. (author)

  7. Tritium exchange reactions in imidazole in aqueous and organic solutions

    International Nuclear Information System (INIS)

    Tritium exchange reactions were studied in aqueous and organic solutions of imidazole and methylimidazole. For the exchange in an aqueous solution the mechanism through ylide intermediate formation postulated by VAUGHAN et al. was modified in this study. The rate constant obtained by MASLOVA et al. was found to be too small compared to ours. For the exchange reaction of methylimidazole in an aqueous solution the rate decreased due to the effect of a methyl group attached to the aromatic ring. The C-2 tritiation of imidazole was studied in chloroform, acetone and dioxane for the first time. It was dependent on polymer properties. An intramolecular exchange mechanism was applicable to the trimer while an intermolecular exchange mechanism was applicable to the dimer. The rate constants of the exchange reactions in organic solutions were obtained for both mechanisms. (orig.)

  8. Isovector spin observables in nuclear charge reactions at LAMPF

    International Nuclear Information System (INIS)

    LAMPF has undertaken a major development program to upgrade facilities for nuclear charge-exchange studies at intermediate energies. The major components of this upgrade are a medium-resolution spectrometer and neutron time-of-flight system for good resolution (δ E < 1 MeV) charge-exchange perograms in (n,p) and (p,n) respectively. Major emphasis is placed on polarization phenomena using polarized beams and analyzing the polarization of the outgoing particle

  9. Production and decay of Δ'S in nuclei; emission of coherent pions in charge exchange

    International Nuclear Information System (INIS)

    The decay channels of the Δ resonance formed in nuclei, by the charge exchange reaction (3He,t) at 2 GeV, have been studied, on 2H, 4He, 12C and Pb targets, in exclusive experiments with the large acceptance detector Diogene. The quasi-free channel Δ++ -> p+ π+, the two proton decay channel and the single pion decay channel have been observed and investigated. The emission of coherent pions has been identified. (authors). 8 refs., 11 figs

  10. X-UV SPECTROSCOPY OF LOW ENERGY CHARGE EXCHANGE COLLISIONS

    OpenAIRE

    Bliman, S.; Bonnet, J.; Bonnefoy, M.; Dousson, S.; Fleury, A.; Hitz, D.; Lu Dac, T.; Mayo, M.

    1986-01-01

    In the field of hot plasmas, it is well known that a knowledge of the relation between collisions and radiation is needed. We show that considering the charge exchange process in which a highly charged, low velocity ion impinges on an atom, we have an X-UV light source allowing new developments. Basically, at velocities less than the atomic unit (vo = 2.2 108 cm/s), the capture of one electron will leave the projectile ion in an excited state. The most probably populated level np is dependant...

  11. Charged particle reaction cross sections and nucleosynthesis

    International Nuclear Information System (INIS)

    The role of proton and α-particle induced reactions in carbon, neon, oxygen and silicon burning in massive stars is surveyed. The problems associated with determining thermonuclear reaction rates for reactions with widely spaced resonances and with closely spaced or overlapping resonances are discussed and the associated experimental approaches are reviewed. Experimental techniques which have been used in the measurement of reaction cross sections are discussed and their strengths and weaknesses are identified. Recent developments in attempts to establish reliable statistical-model codes for calculation of reaction cross sections are presented and discussed. The results of experimental tests of statistical model codes are summarised and evaluated

  12. Automatic analysis of JET charge exchange spectra using neural networks

    International Nuclear Information System (INIS)

    The analysis of charge exchange recombination spectra represents a very challenging problem due to the presence of many overlapping spectral lines. Conventional approaches are based on iterative least-squares optimization and suffer from the two difficulties of low speed and the need for a good initial approximation to the solution. This latter problem necessitates considerable human supervision of the analysis procedure. It is shown how neural network techniques allow charge exchange data to be analysed very rapidly, to give an approximate solution without the need for supervision. The network approach is well suited to the fast intershot analysis of large volumes of data, and can readily be implemented in dedicated hardware for real-time applications. The neural network can also be used to provide the initial guess for the standard least-squares algorithm when high accuracy is required. (Author)

  13. Charge transfer reactions in nematic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Wiederrecht, G.P. [Argonne National Lab., IL (United States). Chemistry Div.; Wasielewski, M.R. [Argonne National Lab., IL (United States). Chemistry Div.]|[Northwestern Univ., Evanston, IL (United States). Dept. of Chemistry; Galili, T.; Levanon, H. [Hebrew Univ. of Jerusalem (Israel). Dept. of Physical Chemistry

    1998-07-01

    Ultrafast transient absorption studies of intramolecular photoinduced charge separation and thermal charge recombination were carried out on a molecule consisting of a 4-(N-pyrrolidino)naphthalene-1,8-imide donor (PNI) covalently attached to a pyromellitimide acceptor (PI) dissolved in the liquid crystal 4{prime}-(n-pentyl)-4-cyanobiphenyl (5CB). The temperature dependencies of the charge separation and recombination rates were obtained at temperatures above the nematic-isotropic phase transition of 5CB, where ordered microdomains exist and scattering of visible light by these domains is absent. The authors show that excited state charge separation is dominated by molecular reorientation of 5CB perpendicular to the director within the liquid crystal microdomains. They also show that charge recombination is adiabatic and is controlled by the comparatively slow collective reorientation of the liquid crystal microdomains relative to the orientation of PNI{sup +}-PI{sup {minus}}. They also report the results of time resolved electron paramagnetic resonance (TREPR) studies of photoinduced charge separation in a series of supramolecular compounds dissolved in oriented liquid crystal solvents. These studies permit the determination of the radical pair energy levels as the solvent reorganization energy increases from the low temperature crystalline phase, through the soft glass phase, to the nematic phase of the liquid crystal.

  14. Solar System X-rays from Charge Exchange Processes

    Science.gov (United States)

    Lisse, Carey M.; Christian, D. J.; Bhardwaj, A.; Dennerl, K.; Wolk, S. J.; Bodewits, D.; Combi, M. R.; Zurbuchen, T. H.; Lepri, S. T.

    2013-04-01

    The discovery of high energy x-ray emission in 1996 from comet C/1996 B2 (Hyakutake) uncovered a new class of x-ray emitting objects. Subsequent detections of the morphology, spectra, and time dependence of the x-rays from more than 20 comets have shown that the very soft (E charge-exchange interaction between highly charged solar wind minor ions and the comet's extended neutral atmosphere. Many solar system objects are now known to shine in the X-ray, including Venus, Mars, the Moon, the Earth, Jupiter, and Saturn, with total power outputs on the MW - GW scale. Like comets, the X-ray emission from the Earth's geo-corona, the Jovian & Saturnian aurorae, and the Martian halo are thought to be driven by charge exchange between highly charged minor (heavy) ions in the solar wind and gaseous neutral species in the bodies' atmosphere. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, and those from disks of Mars, Venus, and the Moon are produced by scattering of solar X-rays. The first soft X-ray observations of Earth’s aurora by Chandra shows that it is highly variable, and the giant planet aurorae are fascinating puzzles that are just beginning to yield their secrets and may be the only x-ray sources not driven directly by the Sun in the whole system as well as properties of hot exo-solar Jupiters. Observations of local solar system charge exchange processes can also help inform us about x-rays produced at more distant hot ionized gas/cold neutral gas interfaces, like the heliopause, stellar astrospheres, galactic star forming regions, and starburst galaxies.

  15. Charge exchange in fluid description of partially ionized plasmas

    CERN Document Server

    Vranjes, J; Luna, M

    2015-01-01

    The effects of charge exchange on waves propagating in weakly ionized plasmas are discussed. It is shown that for low-frequency processes, ions and neutrals should be treated as a single fluid with some effective charge on all of them. We have derived a new momentum equation which should be used in such an environment. As a result, the low-frequency magnetic waves can propagate even if particles are not magnetized, which is entirely due to the charge exchange and the fact that it is not possible to separate particles into two different populations as charged and neutral species. So there can be no friction force between ions and neutrals in the usual sense. The mean force per particle is proportional to the ionization ratio $n_i/(n_i+ n_n)$. Regarding the application of the theory to the Alfven wave propagation in the lower solar atmosphere, the results predict that the plane of displacement of the fluid must change by 90 degrees when an Alfven wave propagates from the area where particles are un-magnetized (...

  16. EXFOR BASICS A SHORT GUIDE TO THE NEUTRON REACTION DATA EXCHANGE FORMAT.

    Energy Technology Data Exchange (ETDEWEB)

    MCLANE,V.; NUCLEAR DATA CENTER NETWORK

    2000-05-19

    This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System. EXFOR is the exchange format designed to allow transmission of nuclear reaction data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information is also compiled. The status (e.g., the source of the data) and history (e.g., date of last update) of the data set is also included. EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear reaction data centers. It was originally conceived for the exchange of neutron data and was developed through discussions among personnel from centers situated in Saclay, Vienna, Livermore and Brookhaven. It was accepted as the official exchange format of the neutron data centers at Saclay, Vienna, Brookhaven and Obninsk, at a meeting held in November 1969. As a result of two meetings held in 1975 and 1976 and attended by several charged-particle data centers, the format was further developed and adapted to cover all nuclear reaction data. The exchange format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The EXFOR format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in a format: that is machine-readable (for checking and indicating possible errors); that can be read by personnel (for passing judgment on and correcting errors). The data presently included in the EXFOR exchange file include: a complete compilation of experimental neutron-induced reaction data, a selected compilation of charged-particle-induced reaction data, a selected compilation of photon-induced reaction data.

  17. EXFOR Basics. A short guide to the neutron reaction data exchange format

    International Nuclear Information System (INIS)

    This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System. EXFOR is the exchange format designed to allow transmission of nuclear reaction data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information is also compiled. The status (e.g., the source of the data) and history (e.g., date of last update) of the data set is also included. EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear reaction data centers. It was originally conceived for the exchange of neutron data and was developed through discussions among personnel from centers situated in Saclay, Vienna, Livermore and Brookhaven. It was accepted as the official exchange format of the neutron data centers at Saclay, Vienna, Brookhaven and Obninsk, at a meeting held in November 1969.3 As a result of two meetings held in 1975 and 1976 and attended by several charged-particle data centers, the format was further developed and adapted to cover all nuclear reaction data. The exchange format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The EXFOR format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in a format: l that is machine-readable (for checking and indicating possible errors); l that can be read by personnel (for passing judgment on and correcting errors). The data presently included in the EXFOR exchange file include: a complete compilation of experimental neutron-induced reaction data, a selected compilation of charged-particle-induced reaction data, a selected compilation of photon-induced reaction data

  18. Nuclear data needs in nuclear astrophysics: Charged-particle reactions

    International Nuclear Information System (INIS)

    Progress in understanding a diverse range of astrophysical phenomena - such as the Big Bang, the Sun, the evolution of stars, and stellar explosions - can be significantly aided by improved compilation, evaluation, and dissemination of charged-particle nuclear reaction data. A summary of the charged-particle reaction data needs in these and other astrophysical scenarios is presented, along with recommended future nuclear data projects. (author)

  19. Measurement of pion double charge exchange on carbon-13, carbon-14, magnesium-26, and iron-56

    International Nuclear Information System (INIS)

    Cross sections for the /sup 13,14/C,26Mg,56Fe(π+,π-)/sup 13,14/O,26Si,56Ni reactions were measured with the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility for 120 less than or equal to T/sub π/ less than or equal to 292 MeV and 0 less than or equal to theta less than or equal to 50. The double isobaric analog states (DIAS) are of primary interest. In addition, cross sections for transitions to 14O(0+, 5.92 MeV), 14O(2+, 7.77 MeV), 56Ni(gs), 13O(gs), and 13O(4.21 MeV) are presented. The 13O(4.21 MeV) state is postulated to have J/sup π/ = 1/2-. The data are compared to previously measured double-charge-exchange cross sections on other nuclei, and the systematics of double charge exchange on T greater than or equal to 1 target nuclei leading to the DIAS are studied. Near the Δ33 resonance, cross sections for the DIAS transitions are in disagreement with calculations in which the reaction is treated as sequential charge exchange through the free pion-nucleon amplitude, while for T/sub π/ > 200 MeV the anomalous features of the 164 MeV data are not apparent. This is evidence for significant higher order contributions to the double-charge-exchange amplitude near the reasonable energy. Two theoretical approaches that include two nucleon processes are applied to the DIAS data. 64 references

  20. Isotopic exchange in ion-molecule reactions: interstellar implications

    International Nuclear Information System (INIS)

    The results of a study of the rates of isotopic exchange in several positive ion/molecule reactions are outlined. The data were obtained over the temperature range 90 - 550 K using a SIFT apparatus. Reversible reactions of the kind: 13C+ + 12CO reversible 12C+ + 13CO were studied and the rate coefficients were determined. Other similar reactions studied were those between HCO+ and CO in which the carbon and oxygen were variously isotopically labelled. Differences between the rate coefficients were apparent at the lower temperatures which, it is suggested, contribute to the observed enhanced concentrations of the rarer isotopes in interstellar CO and HCO+. Isotopic exchange in the reactions of CH+, CH2+ and CH3+ with HD and D2 and in the reactions of CD+, CD2+ and CD3+ with HD and H2 has also been studied and these data are briefly discussed. (Auth.)

  1. Cesium exchange reaction on natural and modified clinoptilolite zeolites

    International Nuclear Information System (INIS)

    Cesium cation exchange reaction with K, Na, Ca and Mg ions on natural and modified clinoptilolite has been studied. Batch cation-exchange experiments were performed by placing 0.5 g of clinoptilolite into 10 ml or 20 ml of 1 x 10-3M CsCl solution for differing times. Two type deposits of clinoptilolite zeolites from, Nizny Hrabovec (NH), Slovakia and Metaxades (MX), Greece were used for ion-exchange study. The distribution coefficient (Kd) and sorption capacity (Γ) were evaluated. For the determination of K, Na, Ca and Mg isotachophoresis method, the most common cations in exchange reaction was used. Cesium sorption was studied using 137Cs tracer and measured by γ-spectrometry. (author)

  2. Configuration interaction in charge exchange spectra of tin and xenon

    International Nuclear Information System (INIS)

    Charge-state-specific extreme ultraviolet spectra from both tin ions and xenon ions have been recorded at Tokyo Metropolitan University. The electron cyclotron resonance source spectra were produced from charge exchange collisions between the ions and rare gas target atoms. To identify unknown spectral lines of tin and xenon, atomic structure calculations were performed for Sn14+-Sn17+ and Xe16+-Xe20+ using the Hartree-Fock configuration interaction code of Cowan (1981 The Theory of Atomic Structure and Spectra (Berkeley, CA: University of California Press)). The energies of the capture states involved in the single-electron process that occurs in these slow collisions were estimated using the classical over-barrier model.

  3. CHARGE-EXCHANGE SCATTERING OF NEGATIVE PIONS BY HYDROGEN AT 230,260, 290, 317 AND 371 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Caris, John C

    1960-03-18

    The differential cross section for charge-exchange scattering of negative pions by hydrogen has been observed at 230, 260, 290, 317, and 371 Mev. The reaction was observed by detecting one gamma ray from the {pi}{sup 0} decay with a scintillation-counter telescope.

  4. Temperature dependence of the rate coefficient for charge exchange of metastable O/+//2D/ with N2. [in atmosphere

    Science.gov (United States)

    Torr, M. R.; Torr, D. G.

    1980-01-01

    Using a data base of aeronomical parameters measured on board the Atmosphere Explorer-C satellite, temperature dependence of the reaction rate coefficient is deduced for the charge exchange of O(+)(2D) with N2. The results indicate the Explorer values determined over the temperature range from 700 to 1900 K are not in conflict with laboratory measurements made at higher temperatures.

  5. Laser-Assisted H- Charge Exchange Injection in Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Gorlov, Timofey V [ORNL; Danilov, Viatcheslav V [ORNL; Shishlo, Andrei P [ORNL

    2010-01-01

    The use of stripping foils for charge exchange injection can cause a number of operational problems in high intensity hadron accelerators. A recently proposed three-step method of laser-assisted injection is capable of overcoming these problems. This paper presents advances in the physical model of laser-assisted charge exchange injection of H- beams and covers a wide field of atomic physics. The model allows the calculation of the evolution of an H0 beam taking into account spontaneous emission, field ionization and external electromagnetic fields. Some new data on the hydrogen atom related to the problem are calculated. The numerical calculations in the model use realistic descriptions of laser field and injection beam. Generally, the model can be used for design and optimization of a laser-assisted injection cell within an accelerator lattice. Example calculations of laser-assisted injection for an intermediate experiment at SNS in Oak Ridge and for the PS2 accelerator at CERN are presented. Two different schemes, distinctively characterized by various magnetic fields at the excitation point, are discussed. It was shown that the emittance growth of an injected beam can be drastically decreased by moving excitation point into a strong magnetic field.

  6. Laser-assisted H- charge exchange injection in magnetic fields

    Science.gov (United States)

    Gorlov, T.; Danilov, V.; Shishlo, A.

    2010-05-01

    The use of stripping foils for charge exchange injection can cause a number of operational problems in high intensity hadron accelerators. A recently proposed three-step method of laser-assisted injection is capable of overcoming these problems. This paper presents advances in the physical model of laser-assisted charge exchange injection of H- beams and covers a wide field of atomic physics. The model allows the calculation of the evolution of an H0 beam taking into account spontaneous emission, field ionization, and external electromagnetic fields. Some new data on the hydrogen atom related to the problem are calculated. The numerical calculations in the model use realistic descriptions of laser field and injection beam. Generally, the model can be used for design and optimization of a laser-assisted injection cell within an accelerator lattice. Example calculations of laser-assisted injection for an intermediate experiment at SNS in Oak Ridge and for the PS2 accelerator at CERN are presented. Two different schemes, distinctively characterized by various magnetic fields at the excitation point, are discussed. It was shown that the emittance growth of an injected beam can be drastically decreased by moving the excitation point into a strong magnetic field.

  7. Analysis of JET charge exchange spectra using neural networks

    International Nuclear Information System (INIS)

    Active charge exchange spectra representing the local interaction of injected neutral beams and fully stripped impurity ions are hard to analyse due to strong blending with passive emission from the plasma edge. As a result, the deduced plasma parameters (e.g. ion temperature, rotation velocity, impurity density) cannot always be determined unambiguously. Also, the speed of the analysis is limited by the time consuming nonlinear least-squares minimization procedure. In practice, semi-manual analysis is necessary and fast, automatic analysis, based on currently used techniques, does not seem feasible. In this paper the development of a robust and accurate analysis procedure based on multi-layer perceptron (MLP) neural networks is described. This procedure is fully automatic and fast, thus enabling a real-time analysis of charge exchange spectra. Accuracy has been increased in several ways as compared to earlier straightforward neural network implementations and is comparable to a standard least-squares based analysis. Robustness is achieved by using a combination of different confidence measures. A novel technique for the creation of training data, suitable for high-dimensional inverse problems has been developed and used extensively. A new method for fast calculation of error bars directly from the hidden neurons in a MLP network is also described, and used as part of the confidence calculations. For demonstration purposes, a real-time ion temperature profile diagnostic based on this work has been implemented. (author)

  8. Analysis of JET charge exchange spectra using neural networks

    International Nuclear Information System (INIS)

    Active charge exchange spectra representing the local interaction of injected neutral beams and fully stripped impurity ions are hard to analyse due to the strong blending with passive emission from the plasma edge. As a result, the deduced plasma parameters (e.g. ion temperature, rotation velocity, impurity density) can not always be determined unambiguously. Also, the speed of the analysis is limited by the time consuming non-linear least-squares minimisation procedure. In practice, semi-manual analysis is necessary, and fast, automatic analysis, based on currently used techniques, does not seem feasible. In this paper the development of a robust and accurate analysis procedure based on Multi Layer Perception (MLP) neural networks is described. This procedure is fully automatic and fast, thus enabling a real-time analysis of charge exchange spectra. Accuracy has been increased in several ways as compared to earlier straight-forward neural network implementations and is comparable to a standard least squares based analysis. Robustness is achieved by using a combination of different confidence measures. A novel technique for the creation of training data, suitable for high dimensional inverse problems has been developed, and used extensively. A new method for fast calculation of error bars directly from the hidden neurons in a MLP network is also described, and used as part of the confidence calculations. For demonstration purposes, a real-time ion temperature profile diagnostic based on this has been implemented. (author)

  9. Competition effects in charged particle induced reactions

    International Nuclear Information System (INIS)

    Absolute cross sections have been measured for 14 reactions: 54Cr(p,γ)55Mn for 0.83 MeV less than or equal to E/sub p/ less than or equal to 3.61 MeV, 54Cr(pn,)54Mn for 2.23 MeV less than or equal to E/sub p/ less than or equal to 3.61 MeV, 51V(p,γ)52Cr for 0.93 MeV less than or equal to E/sub p/ less than or equal to 4.47 MeV, 51V(p,n)51Cr for 1.58 MeV 68Zn(p,γ)69Ga for 1.67 MeV less than or equal to E/sub p/ less than or equal to 4.97 MeV, 68Zn(p,n)68Ga for 3.77 MeV less than or equal to E/sub p/ less than or equal to 5.03 MeV, 68Zn(p,γ)65Cu for 3.36 MeV less than or equal to E/sub p/ less than or equal to 5.48 MeV, 48Ca(p,γ)49Sc for 0.58 MeV less than or equal to E/sub p/ less than or equal to 2.67 MeV, 48Ca(p,n,)48Sc for 0.96 less than or equal to E/sub p/ less than or equal to 2.67 MeV, 37Cl(α,γ)41K for 2.90 MeV less than or equal to E/sub α/ less than or equal to 5.23 MeV, 62Ni(α,γ)66Zn for 5.07 MeV less than or equal to E/sub α/ less than or equal to 8.64 MeV, 62Ni(α,n)65Zn for 6.95 MeV less than or equal to E/sub α/ less than or equal to 8.76 MeV, 64Ni(α,γ)68Zn for 4.50 MeV less than or equal to E/sub α/ less than or equal to 7.45 MeV, and 64Ni(α,n)67Zn for 5.29 less than or equal to E/sub α/ less than or equal to 7.44 MeV. Substantial drops in cross section were observed above the neutron thresholds for all the radiative capture reactions except 48Ca(p,γ). In the 48Ca(p,γ)and 68Zn(p,α) reactions significant though smaller neutron competition effects were observed. These cross sections were compared with cross sections calculated with global Hauser-Feshbach models. Criteria for isospin indexing, width fluctuation corrections, and black nuclues strength functions were established

  10. Cold neutral atoms via charge exchange from excited state positronium: a proposal

    CERN Document Server

    Bertsche, W A; Eriksson, S

    2016-01-01

    We present a method for generating cold neutral atoms via charge exchange reactions between trapped ions and Rydberg positronium. The high charge exchange reaction cross section leads to efficient neutralisation of the ions and since the positronium-ion mass ratio is small, the neutrals do not gain appreciable kinetic energy in the process. When the original ions are cold the reaction produces neutrals that can be trapped or further manipulated with electromagnetic fields. Because a wide range of species can be targeted we envisage that our scheme may enable experiments at low temperature that have been hitherto intractable due to a lack of cooling methods. We present an estimate for achievable temperatures, neutral number and density in an experiment where the neutrals are formed at a milli-Kelvin temperature from either directly or sympathetically cooled ions confined on an ion chip. The neutrals may then be confined by their magnetic moment in a co-located magnetic minimum well also formed on the chip. We ...

  11. Diffuse charge and Faradaic reactions in porous electrodes

    OpenAIRE

    Biesheuvel, P. M.; Yu, F; Bazant, M.Z.

    2011-01-01

    Porous electrodes instead of flat electrodes are widely used in electrochemical systems to boost storage capacities for ions and electrons, to improve the transport of mass and charge, and to enhance reaction rates. Existing porous electrode theories make a number of simplifying assumptions: (i) The charge-transfer rate is assumed to depend only on the local electrostatic potential difference between the electrode matrix and the pore solution, without considering the structure of ...

  12. Towards hot electron mediated charge exchange in hyperthermal energy ion-surface interactions

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Thomsen, Lasse Bjørchmar;

    2010-01-01

    electrons useful for driving chemical reactions at surfaces. Using the binary collision approximation and a nonadiabatic model that takes into account the time-varying nature of the ion–surface interaction, the energy loss of the ions is reproduced. The energy loss for Na + ions incident on the devices...... shows that the primary energy loss mechanism is the atomic displacement of Au atoms in the thin film of the metal–oxide–semiconductor device. We propose that neutral particle detection of the scattered flux from a biased device could be a route to hot electron mediated charge exchange....

  13. Neutron-proton charge-exchange amplitudes at 585 MeV

    CERN Document Server

    Chiladze, D; Dzyuba, A; Dymov, S; Glagolev, V; Hartmann, M; Kacharava, A; Keshelashvili, I; Khoukaz, A; Komarov, V; Kulessa, P; Kulikov, A; Lomidze, N; Macharashvili, G; Maeda, Y; Mchedlishvili, D; Mersmann, T; Merzliakov, S; Mielke, M; Mikirtychyants, S; Nekipelov, M; Nioradze, M; Ohm, H; Rathmann, F; Ströher, H; Tabidze, M; Trusov, S; Uzikov, Yu; Valdau, Yu; Wilkin, C

    2008-01-01

    The differential cross section and deuteron analysing powers of the dp -> {pp}n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using a deuteron beam of energy 1170 MeV, data were obtained for small momentum transfers to a {pp} system with low excitation energy. A good quantitative understanding of all the measured observables is provided by the impulse approximation using known neutron-proton amplitudes. The proof of principle achieved here for the method suggests that measurements at higher energies will provide useful information in regions where the existing np database is far less reliable.

  14. Cross sections for ion-molecular reactions in hydrogen systems and for charge transfer reactions of slow multiply charged ions

    International Nuclear Information System (INIS)

    Cross sections of ion-molecular reactions in hydrogen systems of H+-H2, H2+-H2 and H3+-H2 and charge transfer cross sections of multiply charged ions in atomic and molecular targets are presented in graphs and tables of the part A, B and C. All data presented for 99 collision systems have been measured systematically using an octo-pole ion beam guide (OPIG) technique till now since 1985. The part A is for ion-molecular reactions in hydrogen systems. In the lower energy region below few eV in center-of-mass systems, it is seen obviously at a glance that the ion-molecular reaction in hydrogen systems is dominated by H3+ formation process. In the energy region from few eV to few hundred eV in center-of-mass systems, many reaction channels of decay processes from intermediate molecular states seem to be opened resonantly. Some of cross section data in the part B for charge transfer reactions of low-charged ions produced by a conventional electron impact type (Nier type) ion source should be noted to strongly depend on the electron impact energy due to contamination of low lying metastable states in projectile ions. The part C is for charge transfer reactions of multiply charged ions extracted from a small type of electron beam ion source (Mini-EBIS). In measurements using the mini-EBIS, no evidence of metastable ions existing in the primary ion beam has been found except for doubly charged ion beam. The higher energy end of the present cross sections are connected with previous data in fairly good

  15. Characterization of charge-exchange collisions between ultracold $\\rm{^6Li}$ atoms and $\\rm{^{40}Ca^+}$ ions

    CERN Document Server

    Saito, R; Sasakawa, M; Nakai, R; Raoult, M; Silva, H Da; Dulieu, O; Mukaiyama, T

    2016-01-01

    We investigate the energy dependence and the internal-state dependence of the charge-exchange collision cross sections in a mixture of $^6$Li atoms and $^{40}$Ca$^+$ ions in the collision energy range from 0.2 mK to 1 K. Deliberately excited ion micromotion is used to control the collision energy of atoms and ions. The energy dependence of the charge-exchange collision cross section obeys the Langevin model in the temperature range of the current experiment, and the measured magnitude of the cross section is correlated to the internal state of the $^{40}$Ca$^+$ ions. Revealing the relationship between the charge-exchange collision cross sections and the interaction potentials is an important step toward the realization of the full quantum control of the chemical reactions at an ultralow temperature regime.

  16. Multi-Nucleon Exchange in Quasi-Fission Reactions

    CERN Document Server

    Ayik, S; Yilmaz, O

    2015-01-01

    Nucleon exchange mechanism is investigated in the central collisions of ${}^{40}$Ca + ${}^{238}$U and ${}^{48}$Ca + ${}^{238}$U systems near the quasi-fission regime in the framework of the Stochastic Mean-Field (SMF) approach. Sufficiently below the fusion barrier, di-nuclear structure in the collisions is maintained to a large extend. Consequently, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Diffusion coefficients for proton and neutron exchange are determined from the microscopic basis of the SMF approach in the semi-classical framework. Calculations show that after a fast charge equilibration the system drifts toward symmetry over a very long interaction time. Large dispersions of proton and neutron distributions of the produced fragments indicate that diffusion mechanism may help to populate heavy trans-uranium elements near the quasi-fission regime in these collisions.

  17. Charge exchange spectroscopy as a fast ion diagnostic on TEXTOR

    DEFF Research Database (Denmark)

    Delabie, E.; Jaspers, R.J.E.; von Hellermann, M.G.;

    2008-01-01

    active spectroscopy, injected counter the direction in which fast ions injected by the first beam are circulating, we can simultaneously measure a fast ion tail on the blue wing of the D-alpha spectrum while the beam emission spectrum is Doppler shifted to the red wing. An analysis combining the two......An upgraded charge exchange spectroscopy diagnostic has been taken into operation at the TEXTOR tokamak. The angles of the viewing lines with the toroidal magnetic field are close to the pitch angles at birth of fast ions injected by one of the neutral beam injectors. Using another neutral beam for...... parts of the spectrum offers possibilities to improve the accuracy of the absolute (fast) ion density profiles. Fast beam modulation or passive viewing lines cannot be used for background subtraction on this diagnostic setup and therefore the background has to be modeled and fitted to the data together...

  18. Charge exchange measurements of ion behavior in the ISX tokamak

    International Nuclear Information System (INIS)

    Analysis of charge exchange neutrals is the standard method for measuring ion behavior in tokamak plasmas. Limitations of this technique, which arise in dense and neutral-beam-heated plasmas, are discussed. Two refinements that address these limitations are described: a neutral particle analyzer, which incorporates both mass and energy resolution to distinguish different ion components such as the fast and thermal ions in beam-heated plasmas, and an improved data analysis procedure, which accounts for the effects of profiles and neutral attenuation in dense plasmas. A simple two-dimensional Monte Carlo neutral transport code was developed and used to investigate the effects of toroidally asymmetric neutral density profiles. Applications of these methods to experiments in the Impurity Study Experiment (ISX) are discussed; they include energy confinement studies on ISX-A, natural beam heating and high beta studies on ISX-B, and pellet fueling studies on ISX-B

  19. Charge Exchange Losses and Stochastic Acceleration in the Solar Wind

    CERN Document Server

    Kenny, Ciaran

    2016-01-01

    Stochastic acceleration of particles under a pressure balance condition can accommodate the universal $p^{-5}$ spectra observed under many different conditions in the inner heliosphere. In this model, in order to avoid an infinite build up of particle pressure, a relationship between the momentum diffusion of particles and the adiabatic deceleration in the solar wind must exist. This constrains both the spatial and momentum diffusion coefficients and results in the $p^{-5}$ spectrum in the presence of adiabatic losses in the solar wind. However, this theory cannot explain the presence of such spectra beyond the termination shock, where adiabatic deceleration is negligible. To explain this apparent discrepancy, we include the effect of charge exchange losses, resulting in new forms of both the spatial and momentum diffusion coefficients that have not previously been considered. Assuming that the turbulence is of a large-scale compressible nature, we find that a balance between momentum diffusion and losses can...

  20. Resonance charge exchange between excited states in slow proton-hydrogen collisions

    International Nuclear Information System (INIS)

    The theory of resonance charge exchange in slow collisions of a proton with a hydrogen atom in the excited state is developed. It extends the Firsov-Demkov theory of resonance charge exchange to the case of degenerate initial and final states. The theory is illustrated by semiclassical and quantum calculations of charge exchange cross sections between states with n=2 in parabolic and spherical coordinates. The results are compared with existing close-coupling calculations.

  1. Dynamics of helix-coil transition and isotope exchange reaction

    International Nuclear Information System (INIS)

    A dynamical theory is presented for the helix-coil transition and the isotope exchange reaction in a short polypeptide chain. In this theory it is assumed that there is always one and only one helical sequence. The boundaries of the helix are assumed to move randomly along the chain. If we assume slow movement of the boundaries, our model theory explains the experimental results, i.e., the very low rate of the isotope exchange in the central portion of the chain and the site dependence of the rate. (author)

  2. Investor Reaction to Mandatory Offers on the Warsaw Stock Exchange

    Directory of Open Access Journals (Sweden)

    Szymon Okoń

    2012-06-01

    Full Text Available The following paper aims to assess investor reaction to mandatory offers on the Warsaw Stock Exchange, which is important because knowledge about these reactions can be used to make better investment decisions. This paper highlights the importance of procedure in making a mandatory offer and its grounds in the Polish legal system. Additionally, it presents empirical research on the reactions of investors to mandatory offers on the Warsaw Stock Exchange. It has been provided that mandatory offers have a significant impact on the price of a company’s shares listed on the Warsaw Stock Exchange. Knowledge about the reactions of investors to a mandatory offer may be used when selecting securities for an investment portfolio. The findings may provide guidance in deciding whether to begin or end investment in the company, both for individual and institutional investors. The event study methodology approach used in the paper is regarded as valuable and can be the basis for further research in other areas of the capital market research, especially in the context of information efficiency.

  3. Self-affine roughness influence on redox reaction charge admittance

    NARCIS (Netherlands)

    Palasantzas, G

    2005-01-01

    In this work we investigate the influence of self-affine electrode roughness on the admittance of redox reactions during facile charge transfer kinetics. The self-affine roughness is characterized by the rms roughness amplitude w, the correlation length xi and the roughness exponent H (0

  4. Fusion reactivity graphs and tables for charged particle reactions

    International Nuclear Information System (INIS)

    Graphs and tables are presented on 31 light isotope fusion reaction parameters [, n, Q/sub +/, nQ/sub +/ (for n = 1020 fuel ion species/m3 and Q/sub +/ = energy release in charged particles)] in the kinetic temperature range 1 to 1000 keV

  5. Observation of Large Enhancement of Charge Exchange Cross Sections with Neutron-Rich Carbon Isotopes

    CERN Document Server

    Tanihata, I; Kanungo, R; Ameil, F; Atkinson, J; Ayyad, Y; Cortina-Gil, D; Dillmann, I; Estradé, A; Evdokimov, A; Farinon, F; Geissel, H; Guastalla, G; Janik, R; Knoebel, R; Kurcewicz, J; Litvinov, Yu A; Marta, M; Mostazo, M; Mukha, I; Nociforo, C; Ong, H J; Pietri, S; Prochazka, A; Scheidenberger, C; Sitar, B; Strmen, P; Takechi, M; Tanaka, J; Toki, H; Vargas, J; Winfield, J S; Weick, H

    2015-01-01

    Production cross sections of nitrogen isotopes from high-energy carbon isotopes on hydrogen and carbon targets have been measured for the first time for a wide range of isotopes. The fragment separator FRS at GSI was used to deliver C isotope beams. The cross sections of the production of N isotopes were determined by charge measurements of forward going fragments. The cross sections show a rapid increase with the number of neutrons in the projectile. Since the production of nitrogen is mostly due to charge exchange reactions below the proton separation energies, the present data suggests a concentration of Gamow-Teller and Fermi transition strength at low excitation energies for neutron-rich isotopes. It was also observed that the cross sections were enhanced much more strongly for neutron rich isotopes in the C-target data.

  6. Solar Wind Charge Exchange Studies Of Highly Charged Ions On Atomic Hydrogen

    International Nuclear Information System (INIS)

    Accurate studies of low-energy charge exchange (CX) are critical to understanding underlying soft X-ray radiation processes in the interaction of highly charged ions from the solar wind with the neutral atoms and molecules in the heliosphere, cometary comas, planetary atmospheres, interstellar winds, etc.. Particularly important are the CX cross sections for bare, H-like, and He-like ions of C, N, O and Ne, which are the dominant charge states for these heavier elements in the solar wind. Absolute total cross sections for single electron capture by H-like ions of C, N, O and fully-stripped O ions from atomic hydrogen have been measured in an expanded range of relative collision energies (5 eV/u-20 keV/u) and compared to previous H-oven measurements. The present measurements are performed using a merged-beams technique with intense highly charged ion beams extracted from a 14.5 GHz ECR ion source installed on a high voltage platform at the Oak Ridge National Laboratory. For the collision energy range of 0.3 keV/u-3.3 keV/u, which corresponds to typical ion velocities in the solar wind, the new measurements are in good agreement with previous H-oven measurements. The experimental results are discussed in detail and compared with theoretical calculations where available.

  7. Charge Symmetry Breaking and Nuclear Pion Production Reactions

    CERN Document Server

    Bolton, Daniel R

    2011-01-01

    Large momentum transfer reactions such as pion production represent the frontier of Chiral Perturbation Theory and must be understood before more complex reactions can be considered. Pion production is also interesting in its own right, one application being the hadronic extraction of a charge symmetry breaking parameter: the contribution of the down-up quark mass difference to the neutron-proton mass difference. This dissertation reports on two primary projects: (1) a calculation of the charge symmetry breaking forward-backward asymmetry of the differential cross section of the n p -> d pi^0 reaction, and (2) the development of a new theoretical framework addressing the issue of reducibility in the impulse approximation's contribution to pion production. It is shown that the traditional one-body impulse approximation must be replaced by a two-body operator which makes a larger contribution to s-wave pion production.

  8. The search for resonances in the (antiK0 π+π-) system generated in the charge exchange reaction K-p → antiK0π+π-n at 10 GeV/c

    International Nuclear Information System (INIS)

    The author has measured the differential cross sections for the reactions K-p → anti K0π+π-n at 10 GeV/c and determined the differential cross sections for the production of K*(1420) and K*(1800) resonances using a partial wave analysis. (HSI)

  9. EXFOR BASICS A SHORT GUIDE TO THE NEUTRON REACTION DATA EXCHANGE FORMAT.

    Energy Technology Data Exchange (ETDEWEB)

    MCLANE,V.; NUCLEAR DATA CENTER NETWORK

    2000-05-19

    This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System. EXFOR is the exchange format designed to allow transmission of nuclear reaction data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information is also compiled. The status (e.g., the source of the data) and history (e.g., date of last update) of the data set is also included. EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear reaction data centers. It was originally conceived for the exchange of neutron data and was developed through discussions among personnel from centers situated in Saclay, Vienna, Livermore and Brookhaven. It was accepted as the official exchange format of the neutron data centers at Saclay, Vienna, Brookhaven and Obninsk, at a meeting held in November 1969.3 As a result of two meetings held in 1975 and 1976 and attended by several charged-particle data centers, the format was further developed and adapted to cover all nuclear reaction data. The exchange format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The EXFOR format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in a format: l that is machine-readable (for checking and indicating possible errors); l that can be read by personnel (for passing judgment on and correcting errors). The data presently included in the EXFOR exchange file include: a complete compilation of experimental neutron-induced reaction data, a selected compilation of charged-particle-induced reaction data, a selected compilation of photon-induced reaction data.

  10. Plasma code for astrophysical charge exchange emission at X-ray wavelengths

    CERN Document Server

    Gu, Liyi; Raassen, A J J

    2016-01-01

    Charge exchange X-ray emission provides unique insights into the interactions between cold and hot astrophysical plasmas. Besides its own profound science, this emission is also technically crucial to all observations in the X-ray band, since charge exchange with the solar wind often contributes a significant foreground component that contaminates the signal of interest. By approximating the cross sections resolved to $n$ and $l$ atomic subshells, and carrying out complete radiative cascade calculation, we create a new spectral code to evaluate the charge exchange emission in the X-ray band. Comparing to collisional thermal emission, charge exchange radiation exhibits enhanced lines from large-$n$ shells to the ground, as well as large forbidden-to-resonance ratios of triplet transitions. Our new model successfully reproduces an observed high-quality spectrum of comet C/2000 WM1 (LINEAR), which emits purely by charge exchange between solar wind ions and cometary neutrals. It demonstrates that a proper charge ...

  11. EXFOR SYSTEMS MANUAL NUCLEAR REACTION DATA EXCHANGE FORMAT.

    Energy Technology Data Exchange (ETDEWEB)

    MCLANE,V.; NUCLEAR DATA CENTER NETWORK

    2000-05-19

    EXFOR is an exchange format designed to allow transmission of nuclear reaction data between the members of the Nuclear Data Centers Network. This document has been written for use by the members of the Network and includes matters of procedure and protocol, as well as detailed rules for the compilation of data. Users may prefer to consult EXFOR Basics' for a brief description of the format.

  12. Measurement of the acidities of several cation-exchange resins using hydrogen-isotope exchange reaction

    International Nuclear Information System (INIS)

    The hydrogen-isotope exchange reaction between ethanol (unlabeled) and one of three cation-exchange resins labeled with tritium has been observed at 40-80degC. The acidity (acidity based on kinetic logic) at each temperature has been obtained from a A'-McKay plot based on the respective data obtained. The following results have been obtained on the basis of both the acidities obtained in this work and the acidities (of several materials) obtained previously. (1) The order of the reactivity is (Amberlite IRC-76)>(Dowex A-1)>(PVA2000>(Amberlite IRC-50) at 60degC. (2) The higher the temperature, the larger is the reactivity of each material. (3) The temperature dependence of the reactivity of Dowex A-1 is the largest in the four. (4) The reactivity of the functional group (i.e., COOH group or OH group) bonded to the polymer chain can be clarified using the A'-McKay plot method. (5) It seems that method can be applied to analyze other reactions, e.g., other isotope-exchange reactions, surface reactions, catalytic reactions, etc. (author)

  13. Characteristics of solid-target charge-exchange analyzers for energetic ion diagnostics on tokamaks

    International Nuclear Information System (INIS)

    Compact electrostatic charge-exchange analyzers have been constructed for installation in areas of high magnetic fields and restricted access near tokamak fusion devices. The analyzers employed carbon stripping foils, and have been calibrated for proton energies between 1 and 70 keV. They have been successfully used to study charge-exchange losses in auxiliary-heated tokamak plasmas

  14. Charge exchange recombination spectroscopy on the T-10 tokamak.

    Science.gov (United States)

    Klyuchnikov, L A; Krupin, V A; Nurgaliev, M R; Korobov, K V; Nemets, A R; Dnestrovskij, A Yu; Tugarinov, S N; Serov, S V; Naumenko, N N

    2016-05-01

    The charge exchange recombination spectroscopy (CXRS) diagnostics on the T-10 tokamak is described. The system is based on a diagnostic neutral beam and includes three high etendue spectrometers designed for the ITER edge CXRS system. A combined two-channel spectrometer is developed for simultaneous measurements of two beam-induced spectral lines using the same lines of sight. A basic element of the combined spectrometer is a transmitting holographic grating designed for the narrow spectral region 5291 ± 100 Å. The whole CXRS system provides simultaneous measurements of two CXRS impurity spectra and Hα beam line. Ion temperature measurements are routinely provided using the C(6+) CXRS spectral line 5291 Å. Simultaneous measurements of carbon densities and one more impurity (oxygen, helium, lithium etc.) are carried out. Two light collecting systems with 9 lines of sight in each system are used in the diagnostics. Spatial resolution is up to 2.5 cm and temporal resolution of 1 ms is defined by the diagnostic neutral beam diameter and pulse duration, respectively. Experimental results are shown to demonstrate a wide range of the CXRS diagnostic capabilities on T-10 for investigation of impurity transport processes in tokamak plasma. Developed diagnostics provides necessary experimental data for studying of plasma electric fields, heat and particle transport processes, and for investigation of geodesic acoustic modes. PMID:27250422

  15. Charge Exchange, from the Laboratory to Galaxy Clusters

    Science.gov (United States)

    Betancourt-Martinez, Gabriele; Beiersdorfer, Peter; Brown, Gregory; Hell, Natalie; Leutenegger, Maurice A.; Porter, Frederick S.; Reynolds, Christopher S.

    2016-04-01

    X-ray emission due to charge exchange (CX) between solar wind ions and neutrals in comets and planetary atmospheres is ubiquitous in the solar system, and is also a significant foreground in all observations from low-Earth orbit. It is also possible that CX is common astrophysically, in any environment where hot plasma and cold gas interact. A current challenge is that theoretical models of CX spectra do not always accurately describe observations, and require further experimental verification. This is especially important to focus on now, as the recent launch of Astro-H is providing us with the first high-resolution spectra of extended x-ray sources. In order to improve our understanding and modeling of CX spectra, we take advantage of the laboratory astrophysics program at the Lawrence Livermore National Laboratory and use an Electron Beam Ion Trap (EBIT) to perform CX experiments, using the EBIT Calorimeter Spectrometer. We present experimental benchmarks that can be used to develop a more comprehensive and accurate CX theory. On the observational side, we also investigate the possibility of CX occurring in the filaments around the central galaxy of the Perseus cluster, NGC 1275. We use Chandra ACIS data, combined with what we know about laboratory CX spectra, to investigate the possibility of CX being a significant contributor to the x-ray emission.

  16. The Solar Wind Charge-Exchange Production Factor for Hydrogen

    CERN Document Server

    Kuntz, K D; Collier, M R; Connor, H K; Cravens, T E; Koutroumpa, D; Porter, F S; Robertson, I P; Sibeck, D G; Snowden, S L; Thomas, N E; Wash, B M

    2015-01-01

    The production factor, or broad band averaged cross-section, for solar wind charge-exchange with hydrogen producing emission in the ROSAT 1/4 keV (R12) band is $3.8\\pm0.2\\times10^{-20}$ count degree$^{-2}$ cm$^4$. This value is derived from a comparison of the Long-Term (background) Enhancements in the ROSAT All-Sky Survey with magnetohysdrodynamic simulations of the magnetosheath. This value is 1.8 to 4.5 times higher than values derived from limited atomic data, suggesting that those values may be missing a large number of faint lines. This production factor is important for deriving the exact amount of 1/4 keV band flux that is due to the Local Hot Bubble, for planning future observations in the 1/4 keV band, and for evaluating proposals for remote sensing of the magnetosheath. The same method cannot be applied to the 3/4 keV band as that band, being composed primarily of the oxygen lines, is far more sensitive to the detailed abundances and ionization balance in the solar wind. We also show, incidentally,...

  17. Charged particle induced prompt nuclear reaction and its applications

    International Nuclear Information System (INIS)

    Charged particle induced prompt nuclear reaction analysis (PNR) not only can analyze the content and concentration of elements in sample sensitively and accurately, but also can measure the distributions of elements with depth in surface and near surface layer. And the method is very simple, rapid and nondestructive, and has good depth resolution. So the PNR is very widely used in many modern science and technique field such as solid state physics, surface physics, electrochemistry, metallurgy and material science and so on. This paper deals with the principle, method and the features of the nuclear reaction analysis induced by charged particle. Especially, the distribution analysis of impurities in sample with depth and the improvement of the depth resolution are discussed in detail. Some actual examples of its application are given

  18. Multidimensional analysis of charged particles from neutron-induced reactions

    International Nuclear Information System (INIS)

    A survey is given of the most recent experimental results obtained using twin gridded ionization chamber constructed at Obninsk, Russia. Peculiarities of (n,α) and (n,f) reactions investigated are discussed. The detailed description ol the method of charge particles spectrometry is presented. Selected results on fission fragment characteristics are discussed more in detail. Present experiments and instrumental developments are focussed on correlations between fragment masses, energies and emission angles and on fine structures in fragment parameter distributions. (author)

  19. Action of Mercaptan and Disulfide in Hydrogen Atom Exchange Reactions

    International Nuclear Information System (INIS)

    Free- radical, photochemical, and high-energy radiation-induced reactions may be catalysed or inhibited by rapid hydrogen atom exchange reactions of mercaptans and disulfides. The radical-induced, light-initiated, and benzophenone-sensitized decarbonylations of aldehydes are catalysed by mercaptans. The chain-propagating hydrogen transfer reaction, R' + RCH = O -> RH + RC = O , is made more rapid by a similar sequence of hydrogen atom transfers involving the sulfur compound: R' + C6H5CH2SH -> RH + C6H5CH2S'; C6H5CH2S + RCH = 0 -> C6H5CH2SH + RC = 0. The photoreduction of benzophenone in 2-propanol leads to benzpinacol by a non-chain reaction via the radicals (C6H5)2C-OH and (CH3)2COH. The reaction is retarded and inhibited by mercaptan and disulfide, which reconvert the radicals to the starting materials by rapid hydrogen transfer reactions and are themselves regenerated in their alternate valence states, each molecule of sulfur compound negating the chemical consequences of many quanta: (C6H5)2C-OH + AS' -> (C6H5)2C = O + ASH; (CH3)2C-OH + ASH -> (CH3)2C = 0 + AS'. Proof of the mechanism is found in: equilibration of initially present mercaptan or disulfide during inhibition; in racemization of optically active alcohol during inhibition; in deuterium exchange during inhibition. Similar inhibition is seen when only one intermediate radical is formed, as in the benzophenone- benzhydrol and acetophenone-α-methyl-benzyl alcohol systems. Inhibition by sulfur compounds, by the same mechanism, is found in the 60Co γ-ray induced conversion of benzophenone to benzpinacol; naphthalene has no protecting effect on benzophenone in the 60Co system, while quenching the photochemical reaction. The protection by sulfur compounds of solutes against radiation damage thus results from hydrogen atom transfer reactions. The photoreduction of benzophenone in an ether is also inhibited by the sulfur compounds, by hydrogen atom transfer reactions. A mechanism exists in this system

  20. A quantum mechanically complete study of H+ + Na(3s) → H(2p) + Na+ charge exchange excitation

    International Nuclear Information System (INIS)

    The H+ + Na → H(2p) + Na+ charge exchange reaction has been studied at collision energies between 1 and 5 keV. At 1 and 2 keV impact energy, this study is 'quantum mechanically complete'; three quantities are necessary and sufficient to fully characterize this process. The experiment involves angle-resolved coincident detection of scattered H particles and Lyman-α photons. Comparison is made to the results of eikonal coupled-channel calculations. (author)

  1. A partial wave analysis of the $\\pi ^0\\pi ^0$ system produced in $\\pi ^-p$ charge exchange collisions

    OpenAIRE

    E791 Collaboration; Gunter, J.; Dzierba, A.

    2000-01-01

    A partial wave analysis of the of the $\\pi ^0\\pi ^0$ system produced in the charge exchange reaction: $\\pi ^-p\\to \\pi ^0\\pi ^0n$ at an incident momentum of $18.3 GeV/c$ is presented as a function of ${\\pi ^0\\pi ^0}$ invariant mass, $m_{\\pi^0\\pi^0}$, and momentum transfer squared, $| {t} |$, from the incident $\\pi^-$ to the outgoing ${\\pi ^0\\pi ^0}$ system.

  2. EXFOR systems manual: Nuclear reaction data exchange format

    International Nuclear Information System (INIS)

    This document describes EXFOR, the exchange format designed to allow transmission of nuclear reaction data between the members of the Nuclear Data Centers Network. In addition to storing the data and its bibliographic information, experimental information, including source of uncertainties, is also compiled. The status and history of the data set is also included, e.g., the source of the data, any updates which have been made, and correlations to other data sets. The exchange format, as outlined, is designed to allow a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in an easily machine-readable format (for checking and indicating possible errors) and a format that can be read by personnel (for passing judgment on and correcting any errors indicated by the machine)

  3. Europa's atmospheric neutral escape: Importance of symmetrical O2 charge exchange

    Science.gov (United States)

    Dols, Vincent J.; Bagenal, Fran; Cassidy, Timothy A.; Crary, Frank J.; Delamere, Peter A.

    2016-01-01

    We model the interaction of the jovian magnetospheric plasma with the atmosphere of Europa using a multi-species chemistry model where the atmospheric distributions of H2 and O2 are prescribed. The plasma flow is idealized as an incompressible flow around a conducting obstacle. We compute changes in plasma composition resulting from this interaction as well as the reaction rates integrated over the simulation domain for several upstream plasma conditions (ion density, ion temperature and flow velocity). We show that for all cases, the main atmospheric loss process is a cascade of symmetrical charge exchanges on O2, which results in the ejection of neutrals. The production rate of ejected neutrals is about an order of magnitude larger than the production of ions. This conclusion is relevant to future missions to Europa that aim to detect fast neutrals. The neutral ejection resulting from this charge exchange creates an oxygen cloud around the orbit of the moon that is very extended radially but also very tenuous, and has not yet been directly detected.

  4. Charge transfer reaction of multi-charged oxygen ions with O2

    Science.gov (United States)

    Holzscheiter, H. M.; Church, D. A.

    1981-10-01

    The reaction rates for charge transfer from O2 to doubly and triply charged oxygen atoms are measured in a demonstration of the measurement capabilities of a system at ultrahigh vacuum with low-energy magnetically confined ions. Ions were produced by electron impact ionization of gas within a Penning-type ion trap, with selective removal of unwanted ionization states by radio-frequency resonant excitation. Ion number mass-to-charge ratio spectra obtained at partial pressures of O2 from 9.9 x 10 to the -9th to 1.5 x 10 to the -7th torr yield rate constants of 1.0 x 10 to the -9th cu cm/sec and 2.5 x 10 to the -9th cu cm/sec for the O(2+) and O(3+) reactions, respectively. Measurements made at a 30% increase of the effective axial well depth of the trap demonstrate that the rate constant is essentially energy independent in the energy range studies, implying that the O(2+) cross section for charge transfer has an inverse velocity dependence of the Langevin type, despite a reaction rate lower than the Langevin valve.

  5. Measurements of the charge exchange and dissociation cross-sections of the H2+ ion in a wide energy range

    International Nuclear Information System (INIS)

    The dissociation, ionisation, and charge exchange cross-sections of molecular hydrogen ions H2+ passing through various gases, have been measured as a function of the energy of the ions. The energy range studied was from 25 to 250 keV. The reaction products, analysed by a magnetic field according to their e/m ratio, are collected on scintillation detectors. Two methods have made it possible to separate the various reactions leading to the formation of particles having the same e/m ratio. The first separates the particles according to their energy, the other selects those arriving simultaneously on two different detectors. The results show a large variation in the charge exchange cross-section with the energy of the H2+ ions. The variations in the dissociation and ionisation cross-sections are less pronounced. For a given energy, the values of the cross-sections increase with the atomic weight of the target particles. These measurements have been extended to the case of H2+ ions passing through a target of charged particles. Preliminary results show an increase in the cross-sections as compared to the preceding case. Finally the scattering of the reaction products has been studied; this scattering is due to the fact that the molecules formed during a reaction are in an unstable state and the nuclei or atoms diverge from each other. (author)

  6. Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions

    CERN Document Server

    Oberhofer, H

    2009-01-01

    We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following earlier work of Wu et al. Phys. Rev. A 72, 024502 (2005), the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge, and present expressions for the constraint forces. The method is applied to the Ru2+-Ru3+ electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories, and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. smaller value for re...

  7. Total cross sections for pion charge exchange on the proton

    Energy Technology Data Exchange (ETDEWEB)

    Breitschopf, J.

    2006-04-28

    This work describes the measurement of total SCX cross sections employing a new 4{pi} scintillation counter to perform transmission measurements in the incident pion energy range from about 38 to 250 MeV. A small 4{pi} detector box consisting of thin plastic scintillators has been constructed. The transmission technique, which was used, relates the number of transmitted charged pions to that of incident beam pions and this way effectively counts events with neutral products. The incoming negative pions were counted by three beam defining counters before they hit a target of very well known size and chemical composition. The target was placed in the box detector which was not sensitive to the neutral particles resulting from the SCX. The total cross section for emerging neutral particles was derived from the comparison of the numbers of the incoming and transmitted charged particles. The total SCX cross section on hydrogen was derived from the transmissions of a CH{sub 2} target, a carbon target and an empty target. For a detailed offline analysis all TDC, QDC and FADC information was recorded in an event by event mode for each triggered beam event. Various corrections had to be applied to the data, such as random correction, the detection of neutrals in the detector, Dalitz decay, pion decay and the radiative pion capture. This measurement covers, as the only experiment, the whole {delta}-resonance and the sp-interference region in one single experimental setup and improves the available data base for the SCX reaction. It is shown that the description of the SCX cross sections is improved if the s-wave amplitudes, that have been fixed essentially by elastic pion-nucleon scattering data, is reduced by (4{+-}1.5)%. The exact value depends on the SCX literature data included and on the parameters of the {delta}{sup 0} Breit-Wigner resonance describing the p{sub 33}-waves. This shows that p-wave as well as s-wave effects should be considered in studies of isospin

  8. Total cross sections for pion charge exchange on the proton

    International Nuclear Information System (INIS)

    This work describes the measurement of total SCX cross sections employing a new 4π scintillation counter to perform transmission measurements in the incident pion energy range from about 38 to 250 MeV. A small 4π detector box consisting of thin plastic scintillators has been constructed. The transmission technique, which was used, relates the number of transmitted charged pions to that of incident beam pions and this way effectively counts events with neutral products. The incoming negative pions were counted by three beam defining counters before they hit a target of very well known size and chemical composition. The target was placed in the box detector which was not sensitive to the neutral particles resulting from the SCX. The total cross section for emerging neutral particles was derived from the comparison of the numbers of the incoming and transmitted charged particles. The total SCX cross section on hydrogen was derived from the transmissions of a CH2 target, a carbon target and an empty target. For a detailed offline analysis all TDC, QDC and FADC information was recorded in an event by event mode for each triggered beam event. Various corrections had to be applied to the data, such as random correction, the detection of neutrals in the detector, Dalitz decay, pion decay and the radiative pion capture. This measurement covers, as the only experiment, the whole Δ-resonance and the sp-interference region in one single experimental setup and improves the available data base for the SCX reaction. It is shown that the description of the SCX cross sections is improved if the s-wave amplitudes, that have been fixed essentially by elastic pion-nucleon scattering data, is reduced by (4±1.5)%. The exact value depends on the SCX literature data included and on the parameters of the Δ0 Breit-Wigner resonance describing the p33-waves. This shows that p-wave as well as s-wave effects should be considered in studies of isospin symmetry breaking. Interestingly, our

  9. Carbon charge exchange analysis in the ITER-like wall environment

    International Nuclear Information System (INIS)

    Charge exchange spectroscopy has long been a key diagnostic tool for fusion plasmas and is well developed in devices with Carbon Plasma-Facing Components. Operation with the ITER-like wall at JET has resulted in changes to the spectrum in the region of the Carbon charge exchange line at 529.06 nm and demonstrates the need to revise the core charge exchange analysis for this line. An investigation has been made of this spectral region in different plasma conditions and the revised description of the spectral lines to be included in the analysis is presented

  10. EXFOR basics: A short guide to the nuclear reaction data exchange format

    International Nuclear Information System (INIS)

    This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System. EXFOR is the exchange format designed to allow transmission of nuclear data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information, including source of uncertainties, is also compiled. The status and history of the data set is also included, e.g., the source of the data, any updates which have been made, and correlations to other data sets. EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear data compilation centers. This format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility. The exchange format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in an easily machine-readable format (for checking and indicating possible errors) and a format that can be read by personnel (for passing judgment on and correcting any errors indicated by the machine). The data presently included in the EXFOR exchange include: a complete compilation of experimental neutron-induced reaction data, a selected compilation of charged-particle induced reaction data, a selected compilation of photon-induced reaction data

  11. A purely classical description of crossings of energy levels and spectroscopic signatures of charge exchange

    International Nuclear Information System (INIS)

    Charge exchange and crossings of corresponding energy levels that enhance charge exchange are strongly connected with problems of energy loss and diagnostics in high-temperature plasmas. Charge exchange has also been proposed as one of the most effective mechanisms for population inversion in the soft x-ray and VUV ranges. One area of the most fundamental theoretical importance in the study of charge exchange is the problem of electron terms in the field of two stationary Coulomb centres (TCC) of charges Z and Z' separated by a distance R. This involves fascinating atomic physics: the terms can have crossings and quasicrossings. These rich features of the TCC problem are also manifest in other areas of physics such as plasma spectroscopy: a quasicrossing of the TCC terms, by enhancing charge exchange, can result in an unusual structure (a dip) in the spectral line profile emitted by a Z-ion from a plasma consisting of both Z- and Z'-ions, as has been shown theoretically and experimentally. The paradigm is that these sophisticated features of the TCC problem and their flourishing applications are inherently quantum phenomena. In this paper we disprove this paradigm. We present a purely classical description of both the crossings of energy levels in the TCC problem and the dips in the corresponding spectral line profiles caused by the crossing (via enhanced charge exchange). Our classical description is based on first principles and does not use any model assumptions. (author)

  12. Dynamics of the molecular and atomic mechanisms for the hydrogen-iodine exchange reaction.

    Science.gov (United States)

    Raff, L. M.; Thompson, D. L.; Sims, L. B.; Porter, R. N.

    1972-01-01

    The molecular and atomic mechanisms for the hydrogen-iodine exchange reaction are treated theoretically by means of extensive classical trajectories calculated on a reasonable potential energy surface on which the single adjustable parameter is the iodine-core effective charge. The analysis shows the molecular mechanism to be dynamically forbidden, but gives an over-all rate constant for the atomic mechanism that is in agreement with the experimental values. It is indicated that the formation of a weak H2I complex plays an important dynamical role if the atomic mechanism is limited to reactions with collision complexes involving no more than two hydrogen atoms and two iodine atoms. Excellent agreement with experiment is obtained for the rate constant for the recombination I+I+H2 yields I2+H2 and its negative temperature coefficient.

  13. Relation of isospin-symmetry breaking correction for superallowed beta decay to energy of charge-exchange giant monopole resonance

    CERN Document Server

    Rodin, Vadim

    2012-01-01

    Having applied an analytical transformation, a new exact representation for the nuclear isospin-symmetry breaking correction $\\delta_C$ to superallowed beta decay is obtained. The correction is shown to be essentially reciprocal to the square of an energy parameter $\\Omega_M$ which characterizes charge-exchange monopole strength distribution. The proportionality coefficient in this relation is determined by basic properties of the ground state of the even-even mother nucleus, and should be reliably calculated in any realistic nuclear model. Therefore, the single parameter $\\Omega_M$ contains all the information about the properties of excited $0^+$ states needed to describe $\\delta_C$. This parameter can possibly be determined experimentally by charge-exchange reactions. Basic quantities of interest are calculated within the isospin-consistent continuum random phase approximation, and the values of $\\delta_C$ are compared with the corresponding results by other approaches.

  14. The Geometric Phase Appears in the Ultracold Hydrogen Exchange Reaction

    CERN Document Server

    Kendrick, Brian K; Balakrishnan, Naduvalath

    2015-01-01

    Quantum reactive scattering calculations for the hydrogen exchange reaction H + H$_2$($v=4$, $j=0$) $\\to$ H + H$_2$($v'$, $j'$) and its isotopic analogues are reported for ultracold collision energies. Due to the unique properties associated with ultracold collisions, it is shown that the geometric phase effectively controls the reactivity. The rotationally resolved rate coefficients computed with and without the geometric phase are shown to differ by up to four orders of magnitude. The effect is also significant in the vibrationally resolved and total rate coefficients. The dynamical origin of the effect is discussed and the large geometric phase effect reported here might be exploited to control the reactivity through the application of external fields or by the selection of a particular nuclear spin state.

  15. Progress on the evaluation of charged particle nuclear reaction data in Sichuan University

    International Nuclear Information System (INIS)

    The evaluations of excitation function of 9 reactions induced by charged particles (p, α, d) have been fulfilled. The evaluated nuclear reactions and the experimental works are presented. The recommended data for each reaction were remarked

  16. Significance of anion exchange in pentachlorophenol sorption by variable-charge soils.

    Science.gov (United States)

    Hyun, Seunghun; Lee, Linda S; Rao, P Suresh C

    2003-01-01

    Sorption data and subsequent predictive models for evaluating acidic pesticide behavior on variable-charge soils are needed to improve pesticide management and environmental stewardship. Previous work demonstrated that sorption of pentachlorophenol (PCP), a model organic acid, was adequately modeled by accounting for pH-and pKa-dependent chemical speciation and using two organic carbon-normalized sorption coefficients; one each for the neutral and anionic species. Such models do not account for organic anion interaction to positively charged surface sites, which can be significant for variable-charge minerals present in weathered soils typical of tropical and subtropical regions. The role of anion exchange in sorption of ionizable chemicals by variable-charge soils was assessed by measuring sorption of PCP by several variable-charge soils from aqueous solutions of CaCl2, CaSO4, Ca(H2PO4)2 as a function of pH. Differences in sorption from phosphate and chloride electrolyte solutions were attributed to pentachlorophenolate interactions with anion exchange sites. Suppression of PCP sorption by phosphate ranged from negligible in a soil with essentially no positively charge sites, as measured by negligible anion exchange capacity, to as much as 69% for variable-charge soils. Pentachlorophenolate exchange correlated well with the ratio of pH-dependent anion exchange capacity to net surface charge. Sorption reversibility of PCP by both CaCl2 and Ca(H2PO4)2 solutions was also demonstrated. Results for PCP clearly demonstrate that sorption to anion exchange sites in variable-charge soils should be considered in assessing pesticide mobility and that phosphate fertilizer application may increase the mobility of acidic pesticides. PMID:12809297

  17. N(+)-N long-range interaction energies and resonance charge exchange

    Science.gov (United States)

    Stallcop, J. R.; Partridge, H.

    1985-01-01

    The aerothermodynamic studies of proposed space missions require atmospheric charge-transfer data. N2(+) eigenstate energies are calculated with use of the complete-active-space self-consistent-field method with an extended Gaussian basis set. The N(+)-N charge-exchange cross section, determined from these energies, agrees with merged-beam measurements. This contradicts the previous theoretical conclusion. A simple physical description of the long-range interaction is presented and should expedite future charge-transfer studies.

  18. X-ray Signature of Charge Exchange in the Spectra of L-shell Iron Ions

    Energy Technology Data Exchange (ETDEWEB)

    Beiersdorfer, P; Schweikhard, L; Liebisch, P; Brown, G V

    2007-01-05

    The X-ray signature of charge exchange between highly charged L-shell iron ions and neutral gas atoms was studied in the laboratory in order to assess its diagnostic utility. Significant differences with spectra formed by electron-impact excitation were observed. In particular, a strong enhancement was found of the emission corresponding to n {le} 4 {yields} n = 2 transitions relative to the n = 3 {yields} n = 2 emission. This enhancement was detectable even with relatively low-resolution X-ray instrumentation (E/{Delta}E {approx} 10) and may enable future identification of charge exchange as a line-formation mechanism in astrophysical spectra.

  19. The Contribution of Reggeon in Charge Exchange Processes

    CERN Document Server

    Yu Feng Zhou; Lian Shou Liu; Yufeng, Zhou; Hongan, Peng; Lianshou, Liu

    1998-01-01

    We discuss in this paper The experimental results on maximum psedo-rapidity Collaboration at HERA. We calculate the contributions of \\regg ($\\rho$-Reggeon associated with $\\rho$ meson) from regge phenomenology and $\\pi^{+}$-exchange from pion cloud model. The results show that neither the \\regg-exchange nor the pion cloud model alone can explain the experimental data well, but after considering both these two processes together, by using Monte Carlo simulation, a good agreement between theoretical results and experimental data is found. This means that in discussing the large rapidity gap phenomena in deep inelastic scattering, both of the two processes play substantial role.

  20. Ion-Isotopic Exchange Reaction Kinetics using Anion Exchange Resins Dowex 550A LC and Indion-930A

    Directory of Open Access Journals (Sweden)

    P.U. Singare

    2014-06-01

    Full Text Available The present paper deals with the characterization of ion exchange resins Dowex 550A LC and Indion-930A based on kinetics of ion-isotopic exchange reactions for which the short lived radioactive isotopes 131I and 82Br were used as a tracers. The study was performed for different concentration of ionic solution varying from 0.001 mol/L to 0.004 mol/L and temperature in the range of 30.0 °C to 45.0 °C. The results indicate that as compared to bromide ion-isotopic exchange reaction, iodide exchange reaction take place at the faster rate. For both the ion-isotopic exchange reactions, under identical experimental conditions, the values of specific reaction rate increases with increase in the ionic concentration and decreases with rise in temperature. It was observed that at 35.00C, 1.000 g of ion exchange resins and 0.002 mol/L labeled iodide ion solution for iodide ion-isotopic exchange reaction, the values of specific reaction rate (min-1, amount of ion exchanged (mmol, initial rate of ion exchange (mmol/min and log Kd were 0.270, 0.342, 0.092 and 11.8 respectively for Dowex 550A LC resin, which was higher than the respective values of 0.156, 0.241, 0.038 and 7.4 as that obtained for Indion-930A resins. From the results, it appears that Dowex 550A LC resins show superior performance over Indion-930A resins under identical experimental conditions.

  1. Japan Charged-Particle Nuclear Reaction Data Group (JCPRG)

    International Nuclear Information System (INIS)

    This it the progress report of the Executive Committee of the Japan Charged-Particle Nuclear Reaction Data Group (JCPRG). Since the last NRDC meeting in June 2003, the group has carried out the following activities: Compilation of CPND for NRDF and EXFOR; Compilation of CPND bibliographies for CINDA; Improvement of Web-based data input system HENDEL; Improvement of NRDF retrieval system DARPE; Development of utilization system for EXFOR and evaluated libraries; Data services for Japanese users. The regular JCPRG budget has ended at March 2001. They are applying a competitive budget for our further activity. The Executive Committee is organized by 7 researchers and 1 secretary. 6 postdoctoral researchers in Meme Media Lab. of Hokkaido Univ., 6 graduated students in Nuclear Physics Laboratory of Hokkaido Univ. and 1 technical staff work part-time. 1.5 equivalent man year is dedicated to NRDC Network activities

  2. Heat, Mass and Charge Transport, and Chemical Reactions at Surfaces

    Directory of Open Access Journals (Sweden)

    Signe Kjelstrup

    2005-03-01

    Full Text Available In this work we derive the excess entropy production rate for heat, mass and charge transport into, out of and across a surface, using as basic variables the excess densities proposed by Gibbs. With the help of these variables we define the surface as an autonomous system (i.e. a surface in local equilibrium and find its excess entropy production rate. This then determines the conjugate fluxes and forces. Equivalent forms of the entropy production rate are given. The forms contain finite differences of intensive variables into and across the surface as driving forces. The general form of the force-flux relations is given. The expressions for the fluxes serve as boundary conditions for integration across heterogeneous systems. Two examples are discussed in more detail. The first example is the practically important coupled transport of heat and mass into and through a liquid-vapor surface. The second example concerns phenomena at electrode surfaces: the coupled transport of heat, mass and charge and a chemical reaction. By assuming that the two sides of the surface can be described as resistances in series, we are able to reduce the number of unknown transport coefficients considerably. For both examples it is shown that the coupling coefficients for heat and mass flow are large at the surface, when the homogeneous phases have a large enthalpy difference. As a consequence it is not sufficient to use, for instance, Fourier’s law for transport of heat across surfaces.

  3. Pion induced double-charge exchange above the resonance

    International Nuclear Information System (INIS)

    The zero degree excitation function for (π+, π-) is calculated for pion energies of 300 to 1400 MeV assuming a sequential mechanism. The cross section around 1225 MeV is 104 smaller than at 800 MeV. Experiments at this energy should be ideal for searches for effects due to exchange currents, and other non-conventional mechanisms. 15 refs

  4. pi^0 pi^0 Scattering Amplitudes and Phase Shifts Obtained by the pi^- P Charge Exchange Process

    OpenAIRE

    Takamatsu, Kunio

    1999-01-01

    The results of the analysis of the pi^0 pi^0 scattering amplitudes obtained with pi^- P charge exchange reaction, pi^- P --> pi^0 pi^0 n, data at 9 GeV/c are presented. The pi^0 pi^0 scattering amplitudes show clear f_0(1370) and f_2(1270) signals in the S and D waves, respectively. The pi^0 pi^0 scattering phase shifts have been obtained below Kbar K threshold and been analyzed by the Interfering Amplitude method with introduction of negative background phases. The results show a S wave reso...

  5. X-Ray Emission Cross Sections following Charge Exchange by Multiply-Charged Ions of Astrophysical Interest

    Energy Technology Data Exchange (ETDEWEB)

    Otranto, S; Olson, R E; Beiersdorfer, P

    2007-03-12

    The CTMC method is used to calculate emission cross sections following charge exchange processes involving highly charged ions of astrophysical interest and typical cometary targets. Comparison is made to experimental data obtained on the EBIT-I machine at Lawrence Livermore National Laboratory LLNL for O{sup 8+} projectiles impinging on different targets at a collision energy of 10 eV/amu. The theoretical cross sections are used together with ion abundances measured by the Advanced Composition Explorer to reproduce cometary spectra. Discrepancies due to different estimated delays of solar wind events between the comet and the Earth-orbiting satellite are discussed.

  6. Integrated analysis and consistency measurement of bremsstrahlung and charge exchange spectroscopy data for the determination of the ion effective charge

    International Nuclear Information System (INIS)

    In the context of Bayesian probability theory, we discuss a model for estimating the plasma ion effective charge Zeff, integrating data from both bremsstrahlung spectroscopy and individual impurity concentrations obtained via charge exchange spectroscopy (CXS). The validity of the model, taking into account statistical as well as systematic uncertainties, is shown via the deviance information criterion. The consistency of the continuum and CXS data regarding Zeff is improved, as measured by the symmetrized Kullback-Leibler divergence and the geodesic distance between the respective Zeff marginal posterior densities.

  7. Removal of charged micropollutants from water by ion-exchange polymers -- effects of competing electrolytes.

    Science.gov (United States)

    Bäuerlein, Patrick S; Ter Laak, Thomas L; Hofman-Caris, Roberta C H M; de Voogt, Pim; Droge, Steven T J

    2012-10-15

    A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H(2)O(2), activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca(2+) solutions compared to similar concentrations of Na(+), while that of anionic compounds is three fold weaker in SO(4)(2-) solutions compared to equal concentrations of Cl(-). PMID:22818952

  8. Atomic hydrogen escape rate due to charge exchange with hot plasmaspheric ions

    Science.gov (United States)

    Maher, L. J.; Tinsley, B. A.

    1977-01-01

    Data on ion and electron temperatures and concentrations to several thousand kilometers of altitude were obtained from the Atmosphere Explorer C satellite for 1974 and to 850 km from Arecibo incoherent scatter radar measurements. These data were used to normalize diffusive equilibrium profiles. From these profiles and by using the neutral atmospheric model of Jacchia (1971) and a new hydrogen model, the charge-exchange-induced neutral hydrogen escape fluxes for equatorial and middle latitudes were calculated. The data confirm earlier estimates that the charge exchange loss is more important than Jeans escape for the earth. It is also found that inside the plasmapause this charge exchange process with hot plasmapheric ions is the major production and loss process for the satellite population in the hydrogen geocorona.

  9. The diurnal and solar cycle variation of the charge exchange induced hydrogen escape flux

    Science.gov (United States)

    Maher, L. J.; Tinsley, B. A.

    1978-01-01

    On the basis of ion temperature and density data at specific points and times in June 1969 provided by the OGO 6 satellite, and altitude profiles of the ion and electron temperature and concentration provided by the Arecibo radar facility over the period February 1972-April 1974, the diurnal and solar cycle variation of the charge-exchange-induced hydrogen escape flux was investigated. It was calculated that for low to moderate solar activity at Arecibo, the diurnal ratio of the maximum-to-minimum charge-exchange-induced hydrogen escape flux was approximately 6 with a peak around noon and a minimum somewhere between 0100 and 0300 h LT. This study of a limited amount of OGO 6 and Arecibo data seems to indicate that the charge-exchange-induced hydrogen escape flux increases as the F(10.7) flux increases for low to moderate solar activity.

  10. X-ray emission measurements following charge exchange between C$^{6+}$ and H$_2$

    CERN Document Server

    Fogle, M; Morgan, K; McCammon, D; Seely, D G; Draganić, I N; Havener, C C

    2014-01-01

    Lyman x-ray spectra following charge exchange between C$^{6+}$ and H$_2$ are presented for collision velocities between 400 and 2300 km/s (1--30 keV/amu). Spectra were measured by a microcalorimeter x-ray detector capable of fully resolving the C VI Lyman series emission lines though Lyman-$\\delta$. The ratios of the measured emission lines are sensitive to the angular momentum $l$-states populated during charge exchange and are used to gauge the effectiveness of different $l$-distribution models in predicting Lyman emission due to charge exchange. At low velocities, we observe that both single electron capture and double capture autoionization contribute to Lyman emission and that a statistical $l$-distribution best describes the measured line ratios. At higher velocities single electron capture dominates with the $l$-distribution peaked at the maximum $l$.

  11. Charged-current neutrino-nucleus reactions within the SuSAv2-MEC approach

    CERN Document Server

    Megias, G D; Barbaro, M B; Caballero, J A; Donnelly, T W; Simo, I Ruiz

    2016-01-01

    We present a detailed study of charged-current (CC) neutrino-nucleus reactions in a fully relativis- tic framework and comparisons with recent experiments spanning an energy range from hundreds of MeV up to 100 GeV within the SuperScaling Approach, which is based on the analysis of electron- nucleus scattering data and has been recently improved with the inclusion of Relativistic Mean Field theory effects. We also evaluate and discuss the impact of two-particle two-hole meson-exchange currents (2p-2h MEC) on neutrino-nucleus interactions through the analysis of two-particle two-hole axial and vector contributions to weak response functions in a fully relativistic Fermi gas. The results show a fairly good agreement with experimental data over the whole range of neutrino energies.

  12. Oxygen exchange reaction kinetics for cerium(IV) oxide at 1000 °C

    International Nuclear Information System (INIS)

    Bulk oxygen exchange rate kinetics on CeO2 at 1000 °C were observed to have a first order dependence on the fraction of reaction remaining and to be independent of oxygen partial pressure, total pressure, particle size, and specific surface area. This suggests that the exchange reaction is dominated by an internal chemical reaction that is occurring throughout the bulk of the material, and not at the material surface. Oxygen exchange rates were limited by this internal chemical reaction for all CeO2 powders studied (15 nm to −325 mesh), and had a rate constant of 1.19×10−2 s−1 with a time to completion of 617 s. These results are similar to the exchange rates observed previously on PuO2, suggesting that oxygen exchange on PuO2 may also be dominated by an internal chemical reaction under similar conditions. This work will help guide future experiments on 238PuO2 oxygen exchange reactions. - Graphical abstract: Oxygen exchange kinetics on CeO2 at 1000 °C are independent of a wide range of experimental conditions and exhibit first-order chemical reaction kinetics. - Highlights: • Stable oxygen exchange rates obtained on a variety of CeO2 powders at 1000 °C. • Exchange rates are independent of atmospheric composition and specific surface area. • Exchange rates are limited by an internal chemical reaction, not a surface reaction. • CeO2 exchange rates appear similar to the rates observed on PuO2 at 1000 °C

  13. Charge exchange momentum transfer due to ion beam injection in partially ionized plasmas

    International Nuclear Information System (INIS)

    Time responses of a helium plasma to helium gas puffing without and with helium beam injection in a linear plasma device are experimentally investigated. Increase in the neutral density due to gas puffing is suppressed by ion beam injection. The experimental results show that a momentum transport from the ion beam to the puffed neutral particles occurs due to the charge exchange interaction, suggesting that charge exchange momentum transport is one of the processes responsible for the spatial redistribution of neutral atoms in partially ionized plasmas. (author)

  14. KRATTA, a versatile triple telescope array for charged reaction products

    CERN Document Server

    Łukasik, J; Budzanowski, A; Czech, B; Skwirczyńska, I; Brzychczyk, J; Adamczyk, M; Kupny, S; Lasko, P; Sosin, Z; Wieloch, A; Kiš, M; Leifels, Y; Trautmann, W

    2013-01-01

    A new detection system KRATTA, Krak\\'ow Triple Telescope Array, is presented. This versatile, low threshold, broad energy range system has been built to measure the energy, emission angle, and isotopic composition of light charged reaction products. It consists of 38 independent modules which can be arranged in an arbitrary configuration. A single module, covering actively about 4.5 msr of the solid angle at the optimal distance of 40 cm from the target, consists of three identical, 0.500 mm thick, large area photodiodes, used also for direct detection, and of two CsI(1500 ppm Tl) crystals of 2.5 and 12.5 cm length, respectively. All the signals are digitally processed. The lower identification threshold, due to the thickness of the first photodiode, has been reduced to about 2.5 MeV for protons (~0.065 mm of Si equivalent) by applying a pulse shape analysis. The pulse shape analysis allowed also to decompose the complex signals from the middle photodiode into their ionization and scintillation components and...

  15. Spectroscopic signatures of avoided crossings caused by charge exchange in plasmas

    International Nuclear Information System (INIS)

    Electron terms in the field of two stationary Coulomb centres (TCCs) of charges Z and Z' separated by a distance R are a fundamental problem of quantum mechanics, presenting fascinating atomic physics: the terms show crossings and avoided crossings. In the latter situation, the electron has a much larger probability of tunnelling from one well to the other (i.e. of charge exchange) than in the absence of such degeneracy. These rich features of the TCC problem are also manifest in different areas of physics such as plasma spectroscopy. Recently it was shown experimentally that charge exchange, enhanced by the encounter of two TCC terms, can result in an unusual structure (a dip) in the spectral line profile emitted by a Z ion from a plasma consisting of both Z and Z' ions. In this paper we present a detailed quantitative theory of this phenomenon, in which its origin is directly traced to the avoided crossings of terms in the TCC problem. We show that our theory explains quantitatively all the results of the above experiment where such a dip was observed in a hydrogen line. We also consider in detail several prospective 'radiator-perturber' pairs for observing these signatures of charge exchange in lines of hydrogen-like ions. Further experimental studies of such dips would serve to produce not-yet-available fundamental data on charge exchange between multicharged ions, virtually inaccessible by other experimental methods. (author)

  16. Solar wind charge exchange X-ray emission from Mars Model and data comparison

    OpenAIRE

    Koutroumpa, Dimitra; Modolo, Ronan; Chanteur, Gerard; Chaufray, Jean-Yves; Kharchenko, Vasili; Lallement, Rosine

    2012-01-01

    Aims. We study the soft X-ray emission induced by charge exchange (CX) collisions between solar-wind, highly charged ions and neutral atoms of the Martian exosphere. Methods. A 3D multi species hybrid simulation model with improved spatial resolution (130 km) is used to describe the interaction between the solar wind and the Martian neutrals. We calculated velocity and density distributions of the solar wind plasma in the Martian environment with realistic planetary ions description, using sp...

  17. Ion slowing down and charge exchange at small impact parameters selected by channeling: superdensity effects

    OpenAIRE

    L'Hoir, A.; Adoui, A.; Barrué, F.; Billebaud, A.; Bosch, F.; Bräuning-Demian, A.; Bräuning, H.; Cassimi, A.; Chevallier, M.; C. Cohen; Dauvergne, D; Demonchy, C.E.; Giot, L.; Kirsch, R.; Gumberidze, A

    2005-01-01

    In two experiments performed with 20-30 MeV/u highly charged heavy ions (Pb56+, U91+) channeled through thin silicon crystals, we observed the original features of superdensity, associated to the glancing collisions with atomic rows undergone by part of the incident projectiles. In particular the very high collision rate yields a quite specific charge exchange regime, that leads to a higher ionization probability than in random conditions. X-ray measurements show that electrons captured in ou...

  18. Method of producing weakly acidic cation exchange resin particles charged with uranyl ions

    Energy Technology Data Exchange (ETDEWEB)

    Abdelmonem, N.; Ringel, H.; Zimmer, E.

    1981-07-21

    Weakly acidic cationic ion exchange resin particles are charged with uranyl ions by contacting the particles step wise with aqueous uranyl nitrate solution at higher uranium concentrations from stage to stage. An alkaline medium is added to the uranyl nitrate solution in each stage to increase the successive pH values of the uranyl nitrate solution contacting the particles in dependence upon the uranium concentration effective for maximum charging of the particles with uranyl ions.

  19. Constraints on Parton Charge Symmetry and Implications for Neutrino Reactions

    Energy Technology Data Exchange (ETDEWEB)

    J.T. Londergan; Anthony Thomas

    2004-07-01

    For the first time, charge symmetry breaking terms in parton distribution functions have been included in a global fit to high energy data. We review the results obtained for both valence and sea quark charge symmetry violation, and we compare these results with the most stringent experimental upper limits on charge symmetry violation for parton distribution functions, and with theoretical estimates of charge symmetry violation. The limits allowed in the global fit would tolerate a rather large violation of charge symmetry. We discuss the implications of this for the extraction of the Weinberg angle in neutrino DIS by the NuTeV collaboration.

  20. Design and operation of the pellet charge exchange diagnostic for measurement of energetic confined alphas and tritons on TFTR

    International Nuclear Information System (INIS)

    Radially-resolved energy and density distributions of the energetic confined alpha particles in D-T experiments on TFTR are being measured by active neutral particle analysis using low-Z impurity pellet injection. When injected into a high temperature plasma, an impurity pellet (e.g. Lithium or Boron) rapidly ablates forming an elongated cloud which is aligned with the magnetic field and moves with the pellet. This ablation cloud provides a dense target with which the alpha particles produced in D-T fusion reactions can charge exchange. A small fraction of the alpha particles incident on the pellet ablation cloud will be converted to helium neutrals whose energy is essentially unchanged by the charge transfer process. By measuring the resultant helium neutrals escaping from the plasma using a mass and energy resolving charge exchange analyzer, this technique offers a direct measurement of the energy distribution of the incident high-energy alpha particles. Other energetic ion species can be detected as well, such as tritons generated in D-D plasmas and H or He3 RF-driven minority ion tails. The diagnostic technique and its application on TFTR are described in detail

  1. The role of electron capture and energy exchange of positively charged particles passing through matter

    OpenAIRE

    Ulmer, W.

    2011-01-01

    The conventional treatment of the Bethe-Bloch equation for protons accounts for electron capture at the end of the projectile track by the small Barkas correction. This is only a possible way for protons, whereas for light and heavier charged nuclei the exchange of energy and charge along the track has to be accounted for by regarding the projectile charge q as a function of the residual energy. This leads to a significant modification of the Bethe-Bloch equation, otherwise the range in a med...

  2. Development of the charge exchange type beam scraper system at the J-PARC

    Science.gov (United States)

    Okabe, K.; Yamamoto, K.; Kinsho, M.

    2016-03-01

    Improvement in injection beam quality at the Japan Proton Accelerator Research Complex 3-GeV rapid cycle synchrotron is to mitigate beam loss at the injection section. We developed a charge-exchange type scraper system with a thin carbon foil to collimate the beam halo in the injection beam line of the synchrotron. The key issue to realize the scraper is a reduction of the beam loss induced by the multiple-scattering effect of charge-exchange foil placed at the scraper head. In order to determine the adequate foil thickness, a charge-exchange efficiency of a carbon foil and particle-tracking simulation study of the collimated beam have been performed assuming a realistic halo at the scraper section. Using the results of this study, we chose the thickness of a 520 μg /cm2 as the scraper foils to mitigate radiation dose around the L3BT scraper section. A charge-exchange scraper system that prevents the emission of radioactive fragments of the carbon foil was build. The system was put into operation to prove its effectiveness in eliminating the beam halo. From the result of a preliminary beam experiments, we confirmed that the installed scrapers eliminate a transverse beam tail or halo. After two days of operation with beam collimation, the radiation dose level around the scraper section was a tolerable one for the hands-on maintenance.

  3. Short-range NN and NΔ correlations in pion double charge exchange (DCX)

    International Nuclear Information System (INIS)

    I will review several important results related to the short-range nucleon-nucleon and delta-nucleon interaction that have been obtained from recent studies of pion double charge exchange in selected nuclei. 32 refs., 5 figs., 3 tabs

  4. Performance study of the TFTR diagnostic neutral beam for active charge exchange measurements

    International Nuclear Information System (INIS)

    A neutral beam source will be incorporated in the Tokamak Fusion Test Reactor (TFTR) charge exchange diagnostic to provide a time modulated, spatially localized enhancement of the charge exchange efflux. Two autonomous Charge Exchange Neutral Analyzer (CENA) systems are being designed for the TFTR. One system measures the plasma ion temperature along twelve vertical line-of-sight chords spaced approximately equidistantly across the torus minor diameter. The other system is dedicated primarily to measurement of ion phenomena associated with neutral beam injection heating and has a fan-like field of view along eight sight-lines in the equitorial plane. The neutral beam is steerable in order to access the viewing field of both CENA systems, though in general not simultaneously. The performance of the diagnostic neutral beam is evaluated to determine the optimal beam specifications for active charge exchange measurements. Using the optimal beam design parameters, the efficacy of the neutral doping is examined for both CENA systems over the envisioned range of the TFTR plasma density and temperature

  5. Neutron-proton charge exchange scattering from 9 to 23 GeV/c

    International Nuclear Information System (INIS)

    The differential cross sections for neutron-proton charge-exchange scattering have been measured with high statistics in the region of momentum transfer squared 0.0022 and for incident neutron momenta 9< p<=23 GeV/c. (Auth.)

  6. Exchange reactions in the systems of alkali metal, silver and thallium, sulfates, niobates and tantalates

    International Nuclear Information System (INIS)

    Investigated are exchange interactions in diagonal cross sections of twenty triple mutual systems with A and A' cations and SO4 and MO3 anions where A and A'-Li, Na, K, Ag, Tl, M-Nb, Ta using the methods of X-ray phase, chemical and differential thermal analyses. Exchange reaction between crystal complex oxide and melted salt are effective synthesis method. These reactions in particular permitted to obtain pure AgNbO3, AgTaO3 and their solid solutions at temperatures hundreds degrees lower than in displacement reactions. Equilibrium samples of AMO3-A'MO3 systems, continuous or discontinuous solid solutions, compounds (except NaMO3-KMO3, and also LiTaO3-KTaO3) are formed in exchange reactions when there is sulfate shortage. Thus, exchange reactions can be applied for solid solution synthesis, and also for phase diagram study

  7. Improved charge-coupled device detectors for high-speed, charge exchange spectroscopy studies on the DIII-D tokamak

    International Nuclear Information System (INIS)

    Charge exchange spectroscopy is one of the key ion diagnostics on the DIII-D tokamak. It allows determination of ion temperature, poloidal and toroidal velocity, impurity density, and radial electric field Er throughout the plasma. For the 2003 experimental campaign, we replaced the intensified photodiode array detectors on the central portion of the DIII-D charge exchange spectroscopy system with advanced charge-coupled device (CCD) detectors mounted on faster (f/4.7) Czerny-Turner spectrometers equipped with toroidal mirrors. The CCD detectors are improved versions of the ones installed on our edge system in 1999. The combination improved the photoelectron signal level by about a factor of 20 and the signal to noise by a factor of 2-8, depending on the absolute signal level. The new cameras also allow shorter minimum integration times while archiving to PC memory: 0.552 ms for the slower, lower-read noise (15 e) readout mode and 0.274 ms in the faster, higher-read noise (30 e) mode

  8. Charge exchange and energy loss of slowed down heavy ions channeled in silicon crystals

    International Nuclear Information System (INIS)

    This work is devoted to the study of charge exchange processes and of the energy loss of highly charged heavy ions channeled in thin silicon crystals. The two first chapters present the techniques of heavy ion channeling in a crystal, the ion-electron processes and the principle of our simulations (charge exchange and trajectory of channeled ions). The next chapters describe the two experiments performed at the GSI facility in Darmstadt, the main results of which follow: the probability per target atom of the mechanical capture (MEC) of 20 MeV/u U91+ ions as a function of the impact parameter (with the help of our simulations), the observation of the strong polarization of the target electron gas by the study of the radiative capture and the slowing down of Pb81+ ions from 13 to 8,5 MeV/u in channeling conditions for which electron capture is strongly reduced. (author)

  9. Meson exchange current and three-body force contributions to the 4He charge form factor

    International Nuclear Information System (INIS)

    Effects of meson exchange current (MEC) on the charge form factor (CFF) and charge density of 4He are investigated, including pair, mesonic and retardation current terms. The influence of three-body force (3BF) is considered by adopting the realistic wave function obtained from the nuclear Hamiltonian which explicitly includes the two-pion exchange 3BF. As a result the 3BF is found to greatly enhance the MEC contribution. When the 3BF is taken into account, the MEC contribution is shown to remove most of the discrepancy between the theoretical and experimental CFF's at the second maximum. Resulting effects on the charge density are found to yield a depression in the central region. (author)

  10. Achievement of the charge exchange work diminishing of an internal combustion engine in part load

    Directory of Open Access Journals (Sweden)

    Stefan POSTRZEDNIK

    2012-01-01

    Full Text Available Internal combustion engines, used for driving of different cars, occurs not only at full load, but mostly at the part load. The relative load exchange work at the full (nominal engine load is significantly low. At the part load of the IC engine its energy efficiency ηe is significantly lower than in the optimal (nominal field range of the performance parameters. One of the numerous reasons of this effect is regular growing of the relative load exchange work of the IC engine. It is directly connected with the quantitative regulation method commonly used in the IC engines. From the thermodynamic point of view - the main reason of this effect is the throttling process (causing exergy losses occurring in the inlet and outlet channels. The known proposals for solving of this problem are based on applying of the fully electronic control of the motion of inlet, outlet valves and new reference cycles.The idea presented in the paper leads to diminishing the charge exchange work of the IC engines. The problem can be solved using presented in the paper a new concept of the reference cycle (called as eco-cycle of IC engine. The work of the engine basing on the eco-cycle occurs in two 3-stroke stages; the fresh air is delivered only once for both stages, but in range of each stage a new portion of fuel is burned. Normally the charge exchange occurs once during each engine cycle realized. Elaborated proposition bases on the elimination of chosen charge exchange processes and through this the dropping of the charge exchange work can be achieved.

  11. Separation of hydrogen isotopes by exchange reaction between water and hydrogen using hydrophobic platinum catalyst

    International Nuclear Information System (INIS)

    The case of utilizing exchange reaction and distillation has been found very frequently in practical scale in the separation process of hydrogen isotopes such as heavy water and deuterium. Distillation consumes a large quantity of energy, but it is a promising method in future because of the stability and simplicity of the process utilizing phase equilibrium. In the exchange reaction method, there are four excellent reactions involving the exchange reaction between gas and liquid, and in the practical process, counter flow gas-liquid contact towers are used. In this case, single temperature exchange method and double temperature exchange method are conceivable. In order to prevent the condensation of water molecules on active platinum surface, the catalyst has been made hydrophobic. The evaluation of catalyst activity and its basic theory, the lowering of catalyst activity and the effect of regeneration, the rate of exchange reaction and activation energy, and overall mass transfer coefficient are discussed. The performance of hydrogen isotope separation in a counter flow type exchange tower is represented by two factors in gas and liquid phase reactions, and to improve the performance, the transfer at gas-liquid interface must be accelerated, (Kako, I.)

  12. Anion Exchange Capacity As a Mechanism for Deep Soil Carbon Storage in Variable Charge Soils

    Science.gov (United States)

    Dietzen, C.; James, J. N.; Ciol, M.; Harrison, R. B.

    2014-12-01

    Soil is the most important long-term sink for carbon (C) in terrestrial ecosystems, containing more C than plant biomass and the atmosphere combined. However, soil has historically been under-represented in C cycling literature, especially in regards to information about subsurface (>1.0 m) layers and processes. Previous research has indicated that Andisols with large quantities of noncrystalline, variable-charge minerals, including allophane, imogolite, and ferrihydrite, contain more C both in total and at depth than other soil types in the Pacific Northwest. The electrostatic charge of variable-charge soils depends on pH and is sometimes net positive, particularly in acid conditions, such as those commonly developed under the coniferous forests of the Pacific Northwest. However, even soils with a net negative charge may contain a mixture of negative and positive exchange sites and can hold some nutrient anions through the anion exchange capacity. To increase our understanding of the effects of variable-charge on soil organic matter stabilization, deep sampling is under way at the Fall River Long-Term Soil Productivity Site in western Washington. This site has a deep, well-drained soil with few rocks, which developed from weathered basalt and is classified as an Andisol of the Boistfort Series. Samples have been taken to a depth of 3 m at eight depth intervals. In addition to analyzing total soil C, these soils will be analyzed to determine functional groups present, cation exchange capacity, anion exchange capacity, and non-crystalline mineral content. These data will be analyzed to determine any correlations that may exist between these mineralogical characteristics, total soil C, and types of functional groups stored at depth. The most abundant organic functional groups, including carboxylic and phenolic groups, are anionic in nature, and soil positive charge may play an important role in binding and stabilizing soil organic matter and sequestering C.

  13. Development of a utility system for charged particle nuclear reaction data by using intelligentPad

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, Shigeyoshi; Ohbayashi, Yoshihide [Information Processing Center, Kitami Institute of Technology, Kitami, Hokkaido (Japan); Masui, Hiroshi [Meme Media Laboratory, Hokkaido University, Sapporo, Hokkaido (Japan); Kato, Kiyoshi [Hokkaido University, Graduate School of Science, Sapporo, Hokkaido (Japan); Chiba, Masaki [Faculty of Social Information, Sapporo Gakuin Univ., Ebetsu, Hokkaido (Japan)

    2000-03-01

    We have developed a utility system, WinNRDF2, for a nuclear charged particle reaction data of NRDF (Nuclear Reaction Data File) on the IntelligentPad architecture. By using the system, we can search the experimental data of a charged particle reaction of NRDF. Furthermore, we also see the experimental data by using graphic pads which was made through the CONTIP project. (author)

  14. Reactions of charged and neutral recoil particles following nuclear transformations

    International Nuclear Information System (INIS)

    The status of the following programs is reported: study of the stereochemistry of halogen atom or ion reactions produced via (eta,γ) or (IT) nuclear reactions with diastereomeric molecules; study of nuclear decay induced reactions of halogen species with organic compounds in the gas phase; decay-induced labelling of compounds of biochemical interest; energetics and mechanisms involved in the reactions of highly energetic carbon-11 atoms with simple organic molecules; and chemistry of the positronium. (LK)

  15. Theoretical investigation of isotope exchange reaction in tritium-contaminated mineral oil in vacuum pump

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Liang; Xie, Yun [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Du, Liang [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); School of Radiation Medicine and Protection (SRMP), School for Radiological and Interdisciplinary Sciences (RAD-X), Suzhou 215000 (China); Li, Weiyi [School of Physics and Chemistry, Xihua University, Chengdu 610065 (China); Tan, Zhaoyi, E-mail: zhyitan@126.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-04-28

    Highlights: • This is the first theoretical investigation about T–H exchange in vacuum oil. • T–H isotope exchange is accomplished through two different change mechanisms. • Isotope exchange is selective, molecules with −OH and −COOH exchange more easily. • The methyl and methylene radicals in waste oil were observed by {sup 1}HNMR. - Abstract: The mechanism of the isotope exchange reaction between molecular tritium and several typical organic molecules in vacuum pump mineral oil has been investigated by density functional theory (DFT), and the reaction rates are determined by conventional transition state theory (TST). The tritium–hydrogen isotope exchange reaction can proceed with two different mechanisms, the direct T–H exchange mechanism and the hyrogenation–dehydrogenation exchange mechanism. In the direct exchange mechanism, the titrated product is obtained through one-step via a four-membered ring hydrogen migration transition state. In the hyrogenation–dehydrogenation exchange mechanism, the T–H exchange could be accomplished by the hydrogenation of the unsaturated bond with tritium followed by the dehydrogenation of HT. Isotope exchange between hydrogen and tritium is selective, and oil containing molecules with −OH and −COOH groups can more easily exchange hydrogen for tritium. For aldehydes and ketones, the ability of T–H isotope exchange can be determined by the hydrogenation of T{sub 2} or the dehydrogenation of HT. The molecules containing one type of hydrogen provide a single product, while the molecules containing different types of hydrogens provide competitive products. The rate constants are presented to quantitatively estimate the selectivity of the products.

  16. Theoretical investigation of isotope exchange reaction in tritium-contaminated mineral oil in vacuum pump

    International Nuclear Information System (INIS)

    Highlights: • This is the first theoretical investigation about T–H exchange in vacuum oil. • T–H isotope exchange is accomplished through two different change mechanisms. • Isotope exchange is selective, molecules with −OH and −COOH exchange more easily. • The methyl and methylene radicals in waste oil were observed by 1HNMR. - Abstract: The mechanism of the isotope exchange reaction between molecular tritium and several typical organic molecules in vacuum pump mineral oil has been investigated by density functional theory (DFT), and the reaction rates are determined by conventional transition state theory (TST). The tritium–hydrogen isotope exchange reaction can proceed with two different mechanisms, the direct T–H exchange mechanism and the hyrogenation–dehydrogenation exchange mechanism. In the direct exchange mechanism, the titrated product is obtained through one-step via a four-membered ring hydrogen migration transition state. In the hyrogenation–dehydrogenation exchange mechanism, the T–H exchange could be accomplished by the hydrogenation of the unsaturated bond with tritium followed by the dehydrogenation of HT. Isotope exchange between hydrogen and tritium is selective, and oil containing molecules with −OH and −COOH groups can more easily exchange hydrogen for tritium. For aldehydes and ketones, the ability of T–H isotope exchange can be determined by the hydrogenation of T2 or the dehydrogenation of HT. The molecules containing one type of hydrogen provide a single product, while the molecules containing different types of hydrogens provide competitive products. The rate constants are presented to quantitatively estimate the selectivity of the products

  17. Analysis of a Mathematical Model of Lithium-Sulfur Cells Part III: Electrochemical Reaction Kinetics, Transport Properties and Charging

    International Nuclear Information System (INIS)

    Highlights: • The discharge behavior of Li-S cells in wide range of exchange current densities of electrochemical reactions is studied. • Among all reduction reactions, 1/2 S8(l)+e−⇌1/2 S82− and 1/2 S22−+e−⇌2S2− play the most important role in capacity performance. • Low diffusion increases the precipitation of polysulfides in separator which may block the anode surface. • Large solubility of Li2S is needed for the model to be able to simulate the charging process. - Abstract: Sensitivity analysis of a mathematical model of a lithium-sulfur (Li-S) battery was performed by investigating the response of the model to variation of the exchange current densities, diffusion coefficients, and cathode thickness over a wide range; the results of the analysis were used to explain the some aspects of the behavior of the system which may be seen in experiments. In particular, among all the exchange current densities, the exchange current density of the elemental sulfur reduction has the most significant effect on the discharge capacity of the cell. The variation of the diffusion coefficients was also analyzed, providing information on the non-uniformity of precipitants in the cell after discharge. An optimum cathode thickness was presented to gain the highest capacity of the cell. Finally, the simulation of charging was studied, showing that the model needs a large solubility product of di-lithium sulfide to be able to simulate the charge process of a cell

  18. Study of proton polarization in charge exchange process on optically oriented sodium atoms

    International Nuclear Information System (INIS)

    Using high-power adjustable dye lasers for electron spin orientation in a charge-exchange target enables to significantly increase the proton polarization efficiency. A device is described that permits to avoid growth of the polarized proton beam emittance in a charge-exchange process in a strong magnetic field. The devise main feature is the use of an intensive source of neutral hydrogen atoms and the presence of a helium additional charge-exchange target which actualy is a proton ''source''. The helium charge-exchange cell is placed in the same magnetic field of a solenoid where a cell with oriented sodium is placed, a polarized electron being captured by a proton in the latter cell. In this case the beam at the solenoid inlet and outlet is in a neutral state; emittance growth related to the effect of end magnetic fields is not observed. The device after all prouduces polarized protons, their polarization degree is measured and the effect of various factors on polarization degree is studied. The description of the laser source and laser system is given. Measurement results have shown the beam intensity of neutral 7 keV atoms which passed through a polarizer to be 2 mA. The proton current doesn't depend. On the beeld fin the region of chrge exchange for the 8 kGs magnetic field. The degree of sodium polarization was 80% and polarized proton current approximately 70 μA at a temperature of the polarized sodium cell corresponding to the density of sodium vapar approximately 3x1013 at/cm2

  19. A discussion of contributions to the 0νββ decay from the pion-charge-exchange mechanisms

    International Nuclear Information System (INIS)

    The contributions to the amplitude of the 0νββ decay, mediated by the heavy neutrino, from the two kinds of pion-charge-exchange mechanisms were discussed. The point-double-exchange mechanism is much more important for the 0 νββ decay in nuclei, compared to the point-single-exchange mechanism

  20. Ion Exchanger Catalyst Modification for Reactions Involving Lipophilic Reagents

    Czech Academy of Sciences Publication Activity Database

    Hanková, Libuše; Holub, Ladislav; Jeřábek, Karel

    Bratislava: Slovak Society of Chemical Engineering, 2011 - (Markoš, J.), s. 229 ISBN 978-80-227-3503-2. [International Conference of Slovak Society of Chemical Engineering /38./. Tatranské Matliare (SK), 23.05.2011-27.05.2011] Institutional research plan: CEZ:AV0Z40720504 Keywords : ion exchangers * catalysts * lipophilic Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  1. Dithioacetal Exchange: A New Reversible Reaction for Dynamic Combinatorial Chemistry.

    Science.gov (United States)

    Orrillo, A Gastón; Escalante, Andrea M; Furlan, Ricardo L E

    2016-05-10

    Reversibility of dithioacetal bond formation is reported under acidic mild conditions. Its utility for dynamic combinatorial chemistry was explored by combining it with orthogonal disulfide exchange. In such a setup, thiols are positioned at the intersection of both chemistries, constituting a connecting node between temporally separated networks. PMID:26990904

  2. Balance between the physical diffusion and the exchange reaction on binary ionic liquid electrolyte for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Feng; Lin, Hong; Zhang, Jing [State Key Laboratory of New Ceramics and Fine Processing, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China); Li, Jianbao [State Key Laboratory of New Ceramics and Fine Processing, Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory of Ministry of Education for Application Technology of Chemical Materials in Hainan Superior Resources, Hainan Provincial Key Laboratory of Research on Utilization of Si-Zr-Ti Resources, College of Materials Science and Chemical Engineering, Hainan University, Haikou 570228 (China)

    2011-02-01

    A comprehensive characterizations of viscosities, conductivities, triiodide diffusion coefficients, charge-transfer resistances and photovoltaic performance of a potential dye-sensitized solar cell (DSC) electrolyte systems based on binary ionic liquid (IL) mixtures, namely, 1-ethyl-3-methylimidazolium dicyanamide (EMIDCA)/1-methyl-3-propylimidazolium iodide (PMII) with a fixed iodine concentration at varying EMIDCA volume fraction are investigated in the present study. Viscosity and conductivity values are accurately correlated with regard to temperature and EMIDCA volume fraction. The triiodide diffusion coefficients, the predominant electrolyte parameter for limitation of DSC efficiency, are determined by symmetrical cell methods. The physical diffusion and exchange reactions between the iodide and triiodide dominate the apparent triiodide diffusion coefficients at different range of EMIDCA volume fraction. A balance between the viscosity-dependent physical diffusion and the exchange reactions can get at an optimal volume percents of EMIDCA. Impedance spectroscopy and photovoltaic results both support the existence of an optimized binary IL electrolyte composition. Hence, for optimizing an IL-based electrolyte in regards to triiodide transport, a low viscosity is not the exclusive crucial factor since exchange reactions transport effects also play an important role to resolve the diffusion limitation of DSC efficiency. (author)

  3. Balance between the physical diffusion and the exchange reaction on binary ionic liquid electrolyte for dye-sensitized solar cells

    Science.gov (United States)

    Hao, Feng; Lin, Hong; Zhang, Jing; Li, Jianbao

    A comprehensive characterizations of viscosities, conductivities, triiodide diffusion coefficients, charge-transfer resistances and photovoltaic performance of a potential dye-sensitized solar cell (DSC) electrolyte systems based on binary ionic liquid (IL) mixtures, namely, 1-ethyl-3-methylimidazolium dicyanamide (EMIDCA)/1-methyl-3-propylimidazolium iodide (PMII) with a fixed iodine concentration at varying EMIDCA volume fraction are investigated in the present study. Viscosity and conductivity values are accurately correlated with regard to temperature and EMIDCA volume fraction. The triiodide diffusion coefficients, the predominant electrolyte parameter for limitation of DSC efficiency, are determined by symmetrical cell methods. The physical diffusion and exchange reactions between the iodide and triiodide dominate the apparent triiodide diffusion coefficients at different range of EMIDCA volume fraction. A balance between the viscosity-dependent physical diffusion and the exchange reactions can get at an optimal volume percents of EMIDCA. Impedance spectroscopy and photovoltaic results both support the existence of an optimized binary IL electrolyte composition. Hence, for optimizing an IL-based electrolyte in regards to triiodide transport, a low viscosity is not the exclusive crucial factor since exchange reactions transport effects also play an important role to resolve the diffusion limitation of DSC efficiency.

  4. Radiation reaction from electromagnetic fields in the neighborhood of a point charge

    CERN Document Server

    Singal, Ashok K

    2015-01-01

    From the electromagnetic field in the neighborhood of a "point charge" in arbitrary motion, it is shown that the Poynting flux across a spherical surface of vanishingly small radius, surrounding the charge in its instantaneous rest-frame, is nil. The absence of the Poynting flux in the neighborhood of such a charge explicitly shows that there are no radiative losses from an instantly stationary point charge. While this might appear to contradict Larmor's formula for radiation, nevertheless, it is in complete conformity with energy conservation. After all a charge stationary, even if for an instant, possesses no kinetic energy at the moment that could be lost into radiation. Further, from the rate of electromagnetic momentum flow, calculated using the Maxwell stress tensor, across a surface surrounding the charge, the radiation reaction is determined which turns out to be proportional to the first time derivative of the acceleration of the charge. The power loss due to radiation reaction, hitherto derived in t...

  5. Reactions on solid supports. Part-3. Hydrogen isotope exchange reactions catalysed by montmorillonite clay

    International Nuclear Information System (INIS)

    'Deuteriated clay' in which the interlammelar water has been replaced by deuterium oxide can be used for exchange of acidic protons in a variety of organic substrates. β-Keto esters and β-diketones undergo rapid exchange of the methylene protons in chloroform solutions in presence of deuterated clay; pyrrole undergoes exchange of all protons, whereas indoles preferentially undergo exchange at the 3-position as expected, although prolonged exposure to the reagent leads to exchange at other positions. (author). 8 refs. 1 tab

  6. Requirements for charged particle light isotopes reaction data for advanced fuel cycles including two step reaction mechanism

    International Nuclear Information System (INIS)

    Requirements for light charged isotopes nuclear reaction data for advanced fusion fuel cycles are identified. This is performed in the frame of the compilation of charged particle nuclear reaction data. Those reactions are considered which determine the nuclear energy production, burn kinetics, neutron- and radionuclide production among fuel and ash isotopes. Emphasis is put on the fuel p-11B for which a review of the status of existing data is given. Other exotic fuel candidates (e.g. p-6Li) and some exotic reactions occurring in D-3He based fuels are also considered, however in less detail. We conclude that there is a lack of experimental and evaluated data for several important reactions. It is recommended that evaluations be performed, existing ones reexamined, and that they are made easily accessible for the increasing number of researchers studying advanced fuels. (author). 52 refs, 10 figs, 6 tabs

  7. Charge state distribution of 16O from the 4He(12C,16O)γ reaction of astrophysical interest studied both experimentally and theoretically

    International Nuclear Information System (INIS)

    In astrophysics, 4He(12C,16O)γ reaction places an important role. At Kyushu University Tandem accelerator Laboratory (KUTL), the measurement of 4He(12C,16O)γ cross section is in progress in the energy range of astrophysical nuclear reaction. Since the charge state of product 16O ions after passing through the gas target is spread and only one charge state can be measured at terminal detector, it is necessary to know the charge state distribution of 16O ions passing through the He gas target precisely. Here, we report the charge state distribution of the 16O recoils both experimentally and theoretically. Experimentally, we measured the equilibrium charge state distribution of 16O ions in the windowless helium gas target with the beam energy of primary 16O ions at 7.2, 4.5, and 3.45 MeV at KUTL. The measured results showed a Gaussian distribution for the charge state fraction. Theoretically, we proposed a framework for the charge state distribution study. Charge state distribution was computed by solving a set of differential equations including a series of charge exchange cross sections. For the ionization cross section, plane-wave Born approximation was applied and modified by taking target atomic screening as a function of momentum transfer into account. For the capture cross section, continuum distorted wave approximation was applied and the influence of the gas target density was taken into account in the process of electron capture. Using above charge exchange cross sections, the charge state evolution was simulated. According to the equilibrium distribution, we compared the theoretical calculation to the experimental data. After taking into account the density effects in the charge exchange process, the theoretical charge state distributions shows a good agreement with the experimental data. Both experimental and theoretical results are useful to understand the charge fraction of recoil oxygen created via 4He(12C,16O)γ reaction, especially in the energy

  8. Charge-Exchange Neutral Particle Analyzer Diagnostic of TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Fontdecaba, J. M.; Balbin, R.; Petrov, S.; TJ-II team

    2003-07-01

    A description of the Charge Exchange Neutral Particle Analyzers in operation in the heliac flexible TJ-II is reported. A description of the detectors, as well as the operation characteristics, hardware and software used in the control and analysis of the data obtained with the diagnostic is detailed. Two NPAs are in operation in TJ-II. One of them is a 5-channel analyzer and another one is an Acord-12. The 5-channel analyzer provides measurements of charge exchange neutral fluxes at five energy channels, whereas the Acord-12 can measure simultaneously two different hydrogen isotopes (H and D) at six energy channels. Their lines of sight can be varied poloidally in order to observe the different sections of the plasma. (Author) 10 refs.

  9. Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei

    International Nuclear Information System (INIS)

    Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs

  10. Progress in the pellet charge exchange diagnostics on LHD and local neutral particle spectra analysis

    International Nuclear Information System (INIS)

    Production, confinement and thermalization of high-energy particles are the fundamental issues in fusion plasma ion kinetics. The ion distribution function ft(ν, θ, t) and its evolution under the ion cyclotron heating (ICH) and neutral beam injection (NBI) are studied by energy resolved charge exchange neutral particle flux measurements. For helical systems, such as LHD, local diagnostics are required due to the complex 3D magnetic configuration. First radially resolved measurements of local H0 atomic energy spectra have been made on LHD by the pellet charge exchange (PCX) method with a Compact Neutral Particle Analyzer (CNPA). The diagnostic technique, the initial measurement results in the range 10-100 keV and the data analysis are described. (author)

  11. Influence of resonant charge exchange on the viscosity of partially ionized plasma in a magnetic field

    International Nuclear Information System (INIS)

    The influence of resonant charge exchange for ion-atom interaction on the viscosity of partially ionized plasma embedded in the magnetic field is investigated. The general system of equations used to derive the viscosity coefficients for an arbitrary plasma component in the 21-moment approximation of Grad’s method is presented. The expressions for the coefficients of total and partial viscosities of a multicomponent partially ionized plasma in the magnetic field are obtained. As an example, the coefficients of the parallel and transverse viscosities for the ionic and neutral components of the partially ionized hydrogen plasma are calculated. It is shown that the account for resonant charge exchange can lead to a substantial change of the parallel and transverse viscosity of the plasma components in the region of low degrees of ionization on the order of 0.1

  12. Charge exchange contamination of CRIT-II barium CIV experiment. [critical ionization velocity in ionosphere

    Science.gov (United States)

    Swenson, G. R.; Mende, S. B.; Meyerott, R. E.; Rairden, R. L.

    1991-01-01

    Experiments have been recently performed which attempted to confirm critical ionization velocity (CIV) ionization by deploying chemicals at high velocity in the ionosphere. Specifically, the CRIT-II rocket performed a barium release in the ionosphere, where observations of Ba(+) resonant emissions following the release are believed to have resulted from the CIV process. Calculations are presented which suggest a significant fraction (if not all) of the Ba(+) observed likely resulted from charge exchange with the thermosphere ions and not through CIV processes. The results presented here are pertinent to other CIV experiments performed in the ionosphere. It is recommended that laboratory measurements should be made of the charge exchange cross section between O(+) and Ba as well as other metal vapors used in CIV experiments.

  13. Solar wind/local interstellar medium interaction including charge exchange with neural hydrogen

    Science.gov (United States)

    Pauls, H. Louis; Zank, Gary P.

    1995-01-01

    We present results from a hydrodynamic model of the interaction of the solar wind with the local interstellar medium (LISM), self-consistently taking into account the effects of charge exchange between the plasma component and the interstellar neutrals. The simulation is fully time dependent, and is carried out in two or three dimensions, depending on whether the helio-latitudinal dependence of the solar wind speed and number density (both giving rise to three dimensional effects) are included. As a first approximation it is assumed that the neutral component of the flow can be described by a single, isotropic fluid. Clearly, this is not the actual situation, since charge exchange with the supersonic solar wind plasma in the region of the nose results in a 'second' neutral fluid propagating in the opposite direction as that of the LISM neutrals.

  14. Solar Wind Charge Exchange X-ray Emission from Earth's Magnetosheath

    Science.gov (United States)

    Snowden, Steve L.; Kuntz, K. D.

    2016-04-01

    The magnetospheric component of solar wind charge-exchange (SWCX) emission is primarily due to interaction between the high-state ions in the solar wind and the hydrogen in the outermost part of the Earth’s atmosphere. This emission was the primary source of the ROSAT long-term enhancements (LTEs). Using the correlation between the LTEs and the solar wind flux as well as a dynamic models of the magnetosheath, we have derived the 1/4 keV broad-band charge-exchange cross-section, and can show that this method can not be directly applied to the 3/4 keV band. I will discuss the uncertainties in this method and the prospects for improvement.

  15. Analysing powers and spin correlations in deuteron–proton charge exchange at 726 MeV

    Directory of Open Access Journals (Sweden)

    S. Dymov

    2015-05-01

    Full Text Available The charge exchange of vector polarised deuterons on a polarised hydrogen target has been studied in a high statistics experiment at the COSY-ANKE facility at a deuteron beam energy of Td=726 MeV. By selecting two fast protons at low relative energy Epp, the measured analysing powers and spin correlations are sensitive to interference terms between specific neutron–proton charge-exchange amplitudes at a neutron kinetic energy of Tn≈12Td=363 MeV. An impulse approximation calculation, which takes into account corrections due to the angular distribution in the diproton, describes reasonably the dependence of the data on both Epp and the momentum transfer. This lends broad support to the current neutron–proton partial wave solution that was used in the estimation.

  16. Analysing powers and spin correlations in deuteron-proton charge exchange at 726 MeV

    CERN Document Server

    Dymov, S; Bagdasarian, Z; Barsov, S; Carbonell, J; Chiladze, D; Engels, R; Gebel, R; Grigoryev, K; Hartmann, M; Kacharava, A; Khoukaz, A; Komarov, V; Kulessa, P; Kulikov, A; Kurbatov, V; Lomidze, N; Lorentz, B; Macharashvili, G; Mchedlishvili, D; Merzliakov, S; Mielke, M; Mikirtychyants, M; Mikirtychyants, S; Nioradze, M; Ohm, H; Prasuhn, D; Rathmann, F; Serdyuk, V; Seyfarth, H; Shmakova, V; Ströher, H; Tabidze, M; Trusov, S; Tsirkov, D; Uzikov, Yu; Valdau, Yu; Weidemann, C; Wilkin, C

    2015-01-01

    The charge exchange of vector polarised deuterons on a polarised hydrogen target has been studied in a high statistics experiment at the COSY-ANKE facility at a deuteron beam energy of Td = 726 MeV. By selecting two fast protons at low relative energy E_{pp}, the measured analysing powers and spin correlations are sensitive to interference terms between specific neutron-proton charge-exchange amplitudes at a neutron kinetic energy of Tn ~ 1/2 Td =363 MeV. An impulse approximation calculation, which takes into account corrections due to the angular distribution in the diproton, describes reasonably the dependence of the data on both E_{pp} and the momentum transfer. This lends broad support to the current neutron-proton partial-wave solution that was used in the estimation.

  17. ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

    Science.gov (United States)

    Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.; Robertson, I. P.; Sembay, S. F.; Sibeck, D. G.; Stubbs, Timothy J.; Travnicek, P.

    2012-01-01

    We analyze the ROSAT PSPC soft X-ray image of the Moon taken on 29 June 1990 by examining the radial profile of the count rate in three wedges, two wedges (one north and one south) 13-32 degrees off (19 degrees wide) the terminator towards the dark side and one wedge 38 degrees wide centered on the anti-solar direction. The radial profiles of both the north and the south wedges show substantial limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the count rate increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere. Along with Mars, Venus, and Earth, the Moon represents another solar system body at which solar wind charge exchange has been observed. This technique can be used to explore the solar wind-lunar interaction.

  18. Low-energy pion double charge exchange and nucleon-nucleon correlations in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Leitch, M.J.

    1989-01-01

    Recent measurements of pion double-charge exchange (DCX) at energies 20 to 70 MeV are providing a new means for studying nucleon-nucleon correlations in nuclei. At these energies the nucleus is relatively transparent, allowing simpler theoretical models to be used in interpreting the data and leading to a clearer picture. Also the contribution to DCX of sequential charge-exchange scattering through the intermediate analog state is suppressed near 50 MeV and transitions through non-analog intermediate states become very important. Recent theoretical studies by several groups have shown that while transitions through the analog route involve relatively long nucleon-nucleon distances, those through non-analog intermediate states obtain nearly half their strength from nucleon pairs with less than 1 fermi separation. Thus DCX near 50 MeV is an excellent way to study short-range nucleon-nucleon correlations. 31 refs., 29 figs., 4 tabs.

  19. $NN \\to NN \\pi$ reaction near threshold in a covariant one-boson-exchange model

    OpenAIRE

    Shyam, R.; Mosel, U.

    1996-01-01

    We calculate the cross sections for the $p(p,n\\pi^{+})p$ and $p(p,p\\pi^{0})p$ reactions for proton beam energies near threshold in a covariant one-boson-exchange model, which incorporates the exchange of $\\pi$, $\\rho$, $\\sigma$ and $\\omega$ mesons and treats both nucleon and delta isobar as intermediate states. The final state interaction effects have also been included. The $\\omega$ meson exchange is found to contribute significantly at these energies, which, along with other meson exchanges...

  20. Charge separation in synthetic photo-reaction centers

    Energy Technology Data Exchange (ETDEWEB)

    Katz, J.J.

    1978-01-01

    On the basis of electron paramagnetic resonance studies, there is good reason to suppose that the primary electron donor in plant and bacterial photo-reaction centers is a special pair of chlorophyll molecules. The donor--acceptor coordination interactions characteristic of chlorophyll are used to suggest a structure for the chlorophyll special pair. Chlorophyll special pairs with the suggested structure have been prepared in the laboratory. These synthetic reaction centers mimic the essential features of P700 and P865 and provide a useful route to the study of electron transfer from in vivo photo-reaction centers.

  1. Charge-exchange excitations with finite range interactions including tensor terms

    CERN Document Server

    De Donno, V; Anguiano, M; Lallena, A M

    2014-01-01

    We study charge-exchange excitations in doubly magic-nuclei by using a self-consistent Hartree-Fock plus Random Phase Approximation model. We use four Gogny-like finite-range interactions, two of them containing tensor forces. We investigate the effects of the various parts of the tensor forces in the two computational steps of our model, and we find that their presence is not negligible and improves the agreement with the experimental data.

  2. A Schwinger-type variational principle for charge exchange at arbitrary energies

    International Nuclear Information System (INIS)

    An overview of difficulties encountered in charge exchange collision theory is presented. We emphasize problems in the most critical intermediate energy region where, as yet, no adequate method is available. A Schwinger-type variational principle, which is established at arbitrary energies, appears to exhibit many advantages over existing theories. It successfully connects the leading second Born approximation with the efficient L2-expansion methods. (orig.)

  3. Nuclear charge-exchange excitations in localized covariant density functional theory

    International Nuclear Information System (INIS)

    The recent progress in the studies of nuclear charge-exchange excitations with localized covariant density functional theory is briefly presented, by taking the fine structure of spin-dipole excitations in 16O as an example. It is shown that the constraints introduced by the Fock terms of the relativistic Hartree-Fock scheme into the particle-hole residual interactions are straightforward and robust. (authors)

  4. Charge-exchange emission in the starburst galaxies M82 and NGC3256

    CERN Document Server

    Ranalli, Piero

    2012-01-01

    Charge-exchange (CE) emission produces features which are detectable with the current X-ray instrumentation in the brightest near galaxies. We describe these aspects in the observed X-ray spectra of the star forming galaxies M82 and NGC 3256, from the Suzaku and XMM-Newton telescopes. Emission from both ions (O, C) and neutrals (Mg, Si) is recognised. We also describe how microcalorimeter instrumentation on future missions will improve CE observations.

  5. Nuclear charge-exchange excitations in localized covariant density functional theory

    CERN Document Server

    Liang, H Z; Nakatsukasa, T; Niu, Z M; Ring, P; Roca-Maza, X; Van Giai, N; Zhao, P W

    2014-01-01

    The recent progress in the studies of nuclear charge-exchange excitations with localized covariant density functional theory is briefly presented, by taking the fine structure of spin-dipole excitations in 16O as an example. It is shown that the constraints introduced by the Fock terms of the relativistic Hartree-Fock scheme into the particle-hole residual interactions are straightforward and robust.

  6. Kinetic treatment of the heavy ion charge exchange injection in synchrotrons

    CERN Document Server

    Dinev, D

    2002-01-01

    This paper describes the results of a kinetic treatment of the charge exchange injection of heavy ions into synchrotrons. Analytical expressions for the evolution of particle density in the transverse phase space and for the emittance growth due to elastic scattering and energy losses in the stripper have been derived. Numerical examples for the superconducting heavy ion synchrotron Nuclotron in JINR-Dubna are given as well.

  7. Charge-exchange scattering in K- p interactions below 300 MeV/c

    International Nuclear Information System (INIS)

    Cross sections for K-p charge exchange, based on new data equal in statistics to the sum of those of all previous determinations below 300 MeV/c, are presented. The results confirm an earlier observation by this collaboration that the previous measurements of these cross sections at low momentum were significantly underestimated. Evidence for the presence of P wave scattering is presented. (author)

  8. Excitation of thermonuclear reaction in the focus of a precise spherical charge of an exploding sudstance

    International Nuclear Information System (INIS)

    The paper briefly describes the history of gasodynamic thermonuclear fusion development and presents certain results of experiments on excitation of thermonuclear reaction in the focus of a spherical charge of a liquid explosive

  9. Wavelength calibration of the charge exchange recombination spectroscopy system on the DIII-D tokamak

    International Nuclear Information System (INIS)

    A wavelength calibration of all the detectors on the charge exchange recombination spectroscopy (CER) system is performed after every plasma discharge on the DIII-D tokamak. This is done to insure that the rest wavelength position of the C VI 5290.5 angstrom charge exchange line on the detector is accurately known so that the Doppler shift of the spectral line emitted during the discharge can be used for measurements of plasma rotation. In addition, this calibration provides a check on the spectral dispersion needed to determine the ion temperature. The reference spectra for the calibration are Ne I lines created by neon capillary discharge lamps contained within specially designed, diffuse reflectors. The Ne I lines at 3520.4720 angstrom, 5274.0393 angstrom, 5280.0853 angstrom, 5298.1891 angstrom, and 5304.7580 angstrom are used in this work. The location of these lines on the linear detectors can be determined to an accuracy of 0.1 pixel, which corresponds to a plasma rotation accuracy of 1.2 km/s and 0.7 km/s for the central and edge rotation measurements, respectively. Use of oppositely directed views of the plasma at the same major radius have been used to verify that the nominal 5290.5 angstrom wavelength of the C VI (n = 8 → 7) multiplet is the correct wavelength for the line emitted owing to charge exchange excitation

  10. Coherent control of charge exchange in strong-field dissociation of LiF

    Science.gov (United States)

    Armstrong, Greg; Esry, Brett

    2016-05-01

    The alkali-metal-halides family of molecules are useful prototypes in the study of laser-assisted charge exchange. Typically these molecules possess a field-free crossing between the ionic and covalent diabatic Born-Oppenheimer potential curves, leading to Li+ + F- and Li + F in LiF. These channels are energetically well-separated from higher-lying potentials, and may be easily distinguished experimentally. Moreover, charge exchange involves non-adiabatic transitions between the ionic and covalent channels, thereby allowing the investigation of physics beyond the Born-Oppenheimer approximation. The focus of this work is to control the preference between ionic and covalent dissociative products. We solve the time-dependent Schrödinger equation for the nuclear motion in full dimensionality, and investigate a pump-probe scheme for charge-exchange control. The degree of control is investigated by calculating the kinetic-energy release spectrum as a function of pump-probe delay for the ionic and covalent fragments. This work is supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  11. Modeling the Hydrogen-Proton Charge-Exchange Process in Global Heliospheric Simulations

    Science.gov (United States)

    DeStefano, A.; Heerikhuisen, J.

    2015-12-01

    The environment surrounding our Solar System has a vast and dynamic structure. As the Sun rounds the Milky Way galaxy, interstellar dust and gas interact with the Sun's outflow of solar wind. A bubble of hot plasma forms around the Sun due to this interaction, called the heliosphere. In order to understand the structure of the heliosphere, observations and simulations must work in tandem. Within the past decade or so, 3D models of the heliosphere have been developed exhibiting non- symmmetric as well as predicting structures such as the hydrogen wall and the IBEX ribbon. In this poster we explore new ways to compute charge-exchange source terms. The charge-exchange process is the coupling mechanism between the MHD and kinetic theories. The understanding of this process is crucial in order to make valuable predictions. Energy dependant cross section terms will aid in settling non-linear affects coupling the intestellar and solar particles. Through these new ways of computing source terms, resolving fine structures in the plasma in the heliopause may be possible. In addition, other non-trivial situations, such as charge-exchange mediated shocks, may be addressed.

  12. X-ray Emission Measurements following Charge Exchange between C6+ and He

    Energy Technology Data Exchange (ETDEWEB)

    Defay, X [University of Wisconsin, Madison; Morgan, K [University of Wisconsin, Madison; McCammon, D [University of Wisconsin, Madison; Wulf, D. [University of Wisconsin, Madison; Andrianarijaona, V. M. [Pacific Union College; Fogle, Jr., M R, [Auburn University, Auburn, Alabama; Seely, D. G. [Albion College; Draganic, Ilija N [ORNL; Havener, Charles C [ORNL

    2013-01-01

    X-ray spectra following charge exchange collisions between C6+ and He are presented for collision energies between 460 eV/u and 32,000 eV/u. Spectra were obtained at the Oak Ridge National Laboratory ion-atom merged-beams apparatus, using a microcalorimeter X-ray detector capable of fully resolving the C VI Lyman series lines through Ly-gamma. These line ratios are sensitive to the initial electron