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Sample records for charge exchange reactions

  1. 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$^{3+}$.

  2. Charge exchange reaction by Reggeon exchange and W$^{+}$W$^{-}$-fusion

    CERN Document Server

    Schicker, R

    2014-01-01

    Charge exchange reactions at high energies are examined. The existing cross section data on the Reggeon induced reaction pp $\\rightarrow$ n + $\\Delta^{++}$ 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 $W^{\\pm}$-fusion is presented, and the corresponding QCD-background is examined.

  3. 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.

  4. 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

    2016-08-01

    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. Graphical Abstract ᅟ.

  5. 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.

  6. 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.

  7. Nuclear fragmentation and charge-exchange reactions induced by pions in the $\\Delta$-resonance region

    CERN Document Server

    Feng, Zhao-Qing

    2016-01-01

    Dynamics of the nuclear fragmentations and the charge exchange reactions in pion-nucleus collisions near the $\\Delta$(1232) resonance energies has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport model. An isospin, momentum and density-dependent pion-nucleon potential is implemented in the model, which influences the pion dynamics, in particular the kinetic energy spectra, but weakly impacts the fragmentation mechanism. The absorption process in pion-nucleon collisions to form the $\\Delta$(1232) resonance dominates the heating mechanism of target nucleus. The excitation energy transferred to the target nucleus increases with the pion kinetic energy and is similar for both $\\pi^{-}$ and $\\pi^{+}$ induced reactions. The magnitude of fragmentation of target nucleus weakly depends on the pion energy. The isospin ratio in the pion double charge exchange is influenced by the isospin ingredient of target nucleus.

  8. Spin dipole nuclear matrix elements for double beta decay nuclei by charge-exchange reactions

    CERN Document Server

    Ejiri, H

    2016-01-01

    Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (3He,t) charge exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) for low-lying 2- states were derived from the experimental SD strengths by referring to the experimental GT (Gamow-Teller) and F (Fermi) strengths. They are consistent with the empirical SD NMEs based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.

  9. 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 $^9\\mathrm{Be}({\\pi}^-, {\\pi}^+)^9\\mathrm{He}\\ (g.s.)$.

  10. Spin dipole nuclear matrix elements for double beta decay nuclei by charge-exchange reactions

    Science.gov (United States)

    Ejiri, H.; Frekers, D.

    2016-11-01

    Spin dipole (SD) strengths for double beta-decay (DBD) nuclei were studied experimentally for the first time by using measured cross sections of (3He, t) charge-exchange reactions (CERs). Then SD nuclear matrix elements (NMEs) {M}α ({{SD}}) for low-lying 2- states were derived from the experimental SD strengths by referring to the experimental α = GT (Gamow-Teller) and α = F (Fermi) strengths. They are consistent with the empirical NMEs M({{SD}}) based on the quasi-particle model with the empirical effective SD coupling constant. The CERs are used to evaluate the SD NME, which is associated with one of the major components of the neutrino-less DBD NME.

  11. Pion induced double charge exchange reactions in the Delta resonance region

    CERN Document Server

    Buss, O; Larionov, A B; Mosel, U

    2006-01-01

    We have applied the Giessen BUU (GiBUU) transport model to the description of the double charge exchange (DCX) reaction of pions with different nuclear targets at incident kinetic energies of 120-180 MeV . The DCX process is highly sensitive to details of the interactions of pions with the nuclear medium and, therefore, represents a major benchmark for any model of pion scattering off nuclei at low and intermediate energies. The impact of surface effects, such as the neutron skins of heavy nuclei, is investigated. The dependence of the total cross section on the nuclear mass number is also discussed. We achieve a good quantitative agreement with the extensive data set obtained at LAMPF. Furthermore, we compare the solutions of the transport equations obtained in the test-particle ansatz using two different schemes - the full and the parallel ensemble method.

  12. 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.)

  13. 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...

  14. MonChER: Monte-Carlo generator for CHarge Exchange Reactions. Version 1.1. Physics and Manual

    OpenAIRE

    Ryutin, R. A.; Sobol, A E.; Petrov, V. A.

    2011-01-01

    MonChER is a Monte Carlo event generator for simulation of single and double charge exchange reactions in proton-proton collisions at energies from 0.9 to 14 TeV. Such reactions, $pp\\to n+X$ and $pp\\to n+X+n$, are characterized by leading neutron production. They are dominated by $\\pi^+$ exchange and could provide us with more information about total and elastic $\\pi^+ p$ and $\\pi^+\\pi^+$ cross sections and parton distributions in pions in the still unexplored kinematical region.

  15. 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.)

  16. Ionization and Charge Exchange Reactions in Neutral Entrainment of a Field Reversed Configuration Thruster

    Science.gov (United States)

    2012-07-16

    non - Maxwellian . This indicates that a kinetic approach has to be used to model neutral entrainment in FRC thrusters. Strong impact of electron...radiative cooling can be problematic for high-Z plasma (due to a Z2 dependence) and in radiative non -equilibrium conditions (volumetric emission).1...dg, (1) where g is the relative collision velocity and fe is the Maxwellian distribution function. 2. Single charge exchange (SCX, A+ +A → A+A+) For

  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. Comparison of β-decay and Charge-exchange Reactions in Mirror T=2 Nuclei and Isospin Mixing

    Institute of Scientific and Technical Information of China (English)

    B Rubio; A Poves; S E A Orrigo; A Algora; B Blank; Y Fujita; H Fujita; E Ganioglu; W Gelletly; A Montaner-Piza

    2016-01-01

    We have carried outβdecay studies of proton rich nuclei in the fp shell at different laboratories. Here we present our recent results on the β decay of Tz=−2 nuclei performed at GANIL and compare them with the Charge Exchange reactions on their stable, mirror-partner targets, performed at RCNP. In one of the cases, the 56Zn- 56Fe pair, a strong isospin mixing has been observed. The results are well reproduced in the framework of Shell Model calculations.

  20. Polarization creation in proton-rich {sup 28}P via charge exchange reactions and measurement of its electric quadrupole moment

    Energy Technology Data Exchange (ETDEWEB)

    Matsuta, K., E-mail: matsuta@vg.phys.sci.osaka-u.ac.jp; Mihara, M. [Osaka University, Department of Physics (Japan); Zhou, D. M.; Zheng, Y. N. [CIAE (China); Nishimura, D. [Osaka University, Department of Physics (Japan); Nagatomo, T. [International Christian University (Japan); Yuan, D. Q. [CIAE (China); Momota, S. [Kochi University of Technology (Japan); Izumikawa, T. [Niigata University, RI Center (Japan); Zuo, Y.; Fan, P.; Zhu, S. Y. [CIAE (China); Ohtsubo, T. [Niigata University (Japan); Fukuda, M. [Osaka University, Department of Physics (Japan); Namiki, Y.; Nagashima, M. [Niigata University (Japan); Minamisono, T. [Fukui University of Technology (Japan); Kameda, D. [RIKEN (Japan); Sumikama, T. [Tokyo University of Science (Japan); Kitagawa, A. [NIRS (Japan); and others

    2010-06-15

    The degrees of polarization of proton rich nucleus {sup 28}P produced in charge exchange reactions {sup 28}Si + {sup 9}Be {yields} {sup 28}P + X, and {sup 28}Si + {sup 1}H {yields} {sup 28}P + X have been observed at 100A MeV. Utilizing thus obtained polarized nuclei, the magnetic moment of {sup 28}P was remeasured, and vertical bar {mu}({sup 28}P) vertical bar = 0.3115 (34) {mu}{sub N} was obtained. {beta}-nuclear quadrupole resonance ({beta}-NQR) of {sup 28}P implanted in {alpha}-Al{sub 2}O{sub 3} have been observed for the first time, in order to measure the electric quadrupole moment of this nucleus.

  1. Precision evaluation of the Ga-71(nu(e),e(-)) solar neutrino capture rate from the (He-3,t) charge-exchange reaction

    NARCIS (Netherlands)

    Frekers, D.; Adachi, T.; Akimune, H.; Alanssari, M.; Brown, B. A.; Cleveland, B. T.; Ejiri, H.; Fujita, H.; Fujita, Y.; Fujiwara, M.; Gavrin, V. N.; Harakeh, M. N.; Hatanaka, K.; Holl, M.; Iwamoto, C.; Lennarz, A.; Okamoto, A.; Okamura, H.; Suzuki, T.; Tamii, A.

    2015-01-01

    A precision measurement of the Ga-71(He-3,t)Ge-71 charge-exchange reaction was performed. By using a rather complete set of theoretical form factors to describe the cross-section angular distributions over a large angular range, the Gamow-Teller strength distribution up to the effective neutron-sepa

  2. $\\beta$- 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...

  3. Exchange Reaction Between Selenite and Hydroxyl Ion of Variable Charge Soil Surfaces: Ⅱ. Kinetics of Hydroxyl Release

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shi-Wei; ZHANG Gang-Ya; ZHANG Xiao-Nian

    2003-01-01

    A self-made constant pH automated titration instrument was used to study the kinetics of hydroxyl release during selenite reacting with variable charge soils. The rate of hydroxyl release was very rapid at the first several minutes, then gradually slowed down, and at last did not change any more. The experimental data was well fitted by the Langmuir kinetic equation, and with increasing selenite concentration or decreasing solution pH, the reaction lasted longer, the maximum of hydroxyl release (xm) increased, and the binding constant (k) decreased. The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.

  4. 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...

  5. Systematics of pion double charge exchange

    Energy Technology Data Exchange (ETDEWEB)

    Gilman, R.A.

    1985-10-01

    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 / = 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.

  6. Meson exchange currents in pion double charge exchange at high energies

    CERN Document Server

    Alvarez-Ruso, L

    1995-01-01

    In this letter we study the high energy behavior of the forward differential cross section for the O(18)(pi+,pi-)Ne(18) double charge exchange reaction. We have evaluated the sequential and the meson exchange current mechanisms. The meson exchange current contribution shows a very weak energy dependence and becomes dominant at incident pion kinetic energies above 600 MeV.

  7. 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.

  8. Differential cross sections of the charge-exchange reaction pi- p --> pi0 n in the momentum range from 103 to 178 MeV/c

    CERN Document Server

    Mekterović, D; Abaev, V; Bekrenev, V; Bircher, C; Briscoe, W J; Cadman, R V; Clajus, M; Comfort, J R; Craig, K; Grosnick, D; Isenhover, D; Jerkins, M; Joy, M; Knecht, N; Koetke, D D; Kozlenko, N; Kulbardis, A; Kruglov, S; Lolos, G; Lopatin, I; Manley, D M; Manweiler, R; Marušić, A; McDonald, S; Nefkens, B M K; Olmsted, J; Papandreou, Z; Peaslee, D; Peterson, J; Phaisangittisakul, N; Prakhov, S N; Price, J W; Ramírez, A; Sadler, M E; Shafi, A; Spinka, H; Stanislaus, S; Starostin, A; Staudenmaier, H M; Strakovsky, I; Tippens, W B; Watson, S

    2009-01-01

    Measured values of the differential cross sections for pion-nucleon charge exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta.

  9. Differential cross section of the pion-nucleon charge-exchange reaction in the momentum range from 148 to 323 MeV/c

    CERN Document Server

    Sadler, M E; Abaev, V V; Allgower, C; Barker, A; Bekrenev, V; Bircher, C; Briscoe, W J; Cadman, R; Carter, C; Clajus, M; Comfort, J R; Craig, K; Daugherity, M; Draper, B; Grosnick, D P; Hayden, S; Huddleston, J; Isenhower, D; Jerkins, M; Joy, M; Knecht, N; Koetke, D D; Kozlenko, N; Kruglov, S; Kycia, T; Lolos, G J; Lopatin, I; Manley, D M; Manweiler, R; Marusic, A; McDonald, S; Nefkens, B M K; Olmsted, J; Papandreou, Z; Peaslee, D; Peterson, J; Phaisangittisakul, N; Prakhov, S N; Price, J W; Ramírez, A; Robinson, C; Shafi, A; Spinka, H; Stanislaus, S; Starostin, A; Staudenmaier, H M; Strakovsky, I I; Supek, I; Tippens, W B; Watson, S

    2004-01-01

    Measured values of the differential cross section for pion-nucleon charge exchange are presented at momenta 148, 174, 188, 212, 238, 271, 298, and 323 MeV/c, a region dominated by the Delta resonance. Complete angular distributions were obtained using the Crystal Ball detector at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). Statistical uncertainties of the differential cross sections are typically 2-6%, exceptions being the results at the lowest momentum and at the most forward measurements of the five lowest momenta. We estimate the systematic uncertainties to be 3-6%.

  10. Differential cross section of the charge-exchange reaction π- p→ π0 n in the momentum range from 148 to 323 MeV/c

    Science.gov (United States)

    Sadler, M. E.; Kulbardis, A.; Abaev, V.; Allgower, C.; Barker, A.; Bekrenev, V.; Bircher, C.; Briscoe, W. J.; Cadman, R.; Carter, C.; Clajus, M.; Comfort, J. R.; Craig, K.; Daugherity, M.; Draper, B.; Grosnic, D.; Hayden, S.; Huddleston, J.; Isenhower, D.; Jerkins, M.; Joy, M.; Knecht, N.; Koetke, D. D.; Kozlenko, N.; Kruglov, S.; Kycia, T.; Lolos, G.; Lopatin, I.; Manley, D. M.; Manweiler, R.; Marusic, A.; McDonald, S.; Nefkens, B. M.; Olmsted, J.; Papandreou, Z.; Peaslee, D.; Peterson, J.; Phaisangittisakul, N.; Prakhov, S. N.; Price, J. W.; Ramirez, A.; Robinson, C.; Shafi, A.; Spinka, H.; Stanislaus, S.; Starostin, A.; Staudenmaier, H. M.; Strakovsky, I.; Supek, I.; Tippens, W. B.; Watson, S.

    2004-05-01

    Measured values of the differential cross section for pion-nucleon charge exchange, π- p→ π0 n , are presented at π- momenta of 148, 174, 188, 212, 238, 271, 298, and 323 MeV/c , a region dominated by the Δ ( 1232 ) resonance. Complete angular distributions were obtained using the Crystal Ball detector at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). Statistical uncertainties of the differential cross sections are typically 2 6 % , exceptions being the results at the lowest momentum and at the most forward measurements at the five lowest momenta. We estimate the systematic uncertainties to be 3 6 % .

  11. Differential cross sections of the charge-exchange reaction π-p→π0n in the momentum range from 103 to 178 MeV/c

    Science.gov (United States)

    Mekterović, D.; Supek, I.; Abaev, V.; Bekrenev, V.; Bircher, C.; Briscoe, W. J.; Cadman, R. V.; Clajus, M.; Comfort, J. R.; Craig, K.; Grosnick, D.; Isenhover, D.; Jerkins, M.; Joy, M.; Knecht, N.; Koetke, D. D.; Kozlenko, N.; Kulbardis, A.; Kruglov, S.; Lolos, G.; Lopatin, I.; Manley, D. M.; Manweiler, R.; Marušić, A.; McDonald, S.; Nefkens, B. M. K.; Olmsted, J.; Papandreou, Z.; Peaslee, D.; Peterson, J.; Phaisangittisakul, N.; Prakhov, S. N.; Price, J. W.; Ramirez, A.; Sadler, M. E.; Shafi, A.; Spinka, H.; Stanislaus, S.; Starostin, A.; Staudenmaier, H. M.; Strakovsky, I.; Tippens, W. B.; Watson, S.

    2009-11-01

    Measured values of the differential cross sections for pion-nucleon charge exchange, π-p→π0n, are presented for π- momenta of 103,112,120,130,139,152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3 to 6% in the backward angle region and from 6 to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta.

  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 Effect on Space-Charge-Limited Current Densities in Ion Diode

    Institute of Scientific and Technical Information of China (English)

    石磊

    2002-01-01

    The article theoretically studied the charge-exchange effects on space charge limited electron and ion current densities of non-relativistic one-dimensional slab ion diode, and compared with those of without charge exchange.

  14. Double charge exchange at high impact energies

    Science.gov (United States)

    Belkić, Dževad

    1994-03-01

    In fast ion-atom collisions, double ionization always dominates the two-electron transfer. For this reason, an adequate description of double charge exchange requires proper inclusion of intermediate ionization channels. This is even more important in two- than in one-electron transitions. First-order Born-type perturbation theories ignore throughout these electronic continuum intermediate states and hence provide utterly unreliable high energy cross sections for two-electron capture processes. Therefore, it is essential to use second- and higher-order theories, which include the intermediate ionization continua of the two electrons in an approximate manner. In the present paper, a new second-order theory called the Born distorted wave (BDW) approximation is introduced and implemented in the case of symmetric resonant double electron capture from the ground state of helium by fast alpha particles. A genuine four-body formalism is adopted, in contrast to the conventional independent particle model of atomic scattering theory. The obtained results for the total cross sections are compared with the available experimental data, and satisfactory agreement is recorded. As the incident energy increases, a dramatic improvement is obtained in going from the CB1 to the BDW approximation, since the latter closely follows the measurement, whereas the former overestimates the observed total cross sections by two orders of magnitude. This strongly indicates that the role of continuum intermediate states is decisive, even at those incident energies for which the Thomas double scattering effects are not important. This is in sharp contrast to the case of one-electron transfer atomic reactions.

  15. Polarization of {sup 23}Ne, {sup 24m,25}Al and {sup 28}P produced through single nucleon pickup and charge-exchange reactions at 100 AMeV

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsubo, T., E-mail: tohtsubo@np.gs.niigata-u.ac.jp; Hirano, H.; Takahashi, S. [Niigata Univ. (Japan); Matsuta, K.; Mihara, M.; Fukuda, M. [Osaka Univ. (Japan); Nagatomo, T. [RIKEN (Japan); Izumikawa, T. [Niigata Univ., RI Center (Japan); Momota, S. [Kochi Univ. of Tech. (Japan); Nishimura, D.; Komurasaki, J.; Ishikawa, D. [Osaka Univ. (Japan); Zhou, D. M.; Zheng, Y. N.; Zhu, S. Y. [China Institute of Atomic Energy (China); Kitagawa, A.; Kanazawa, M.; Torikoshi, M.; Sato, S. [Inage-ku, NIRS (Japan); Minamisono, T. [Fukui Univ. of Tech. (Japan)

    2007-11-15

    We measured the polarization of the {beta}-emitting {sup 23}Ne (I{sup {pi}} 5/2{sup +}, T{sub 1/2} = 37.24 s) and {sup 25}Al(I{sup {pi}} = 5/2{sup +}, T{sub 1/2} = 7.18 s) produced through the one nucleon pickup reactions and {sup 24m}Al(I{sup {pi}} = 1{sup +}, T{sub 1/2} 131 ms, E{sub ex} = 426 keV) and {sup 28}P(I{sup {pi}} = 3{sup +}, T{sub 1/2} = 270 ms) produced through charge-exchange reactions in the intermediate energy heavy ion collisions. We compared them with those from the projectile fragmentation process. The larger polarization seems to persistently be positive throughout the momentum distribution, and sharper momentum distributions suggest that nuclear friction mechanism is responsible for the polarization phenomena.

  16. Production of antihydrogen via double charge exchange

    Energy Technology Data Exchange (ETDEWEB)

    Muellers, Andreas

    2013-02-01

    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

  17. 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.

  18. Laser controlled charge-transfer reaction at low temperatures

    CERN Document Server

    Petrov, Alexander; Kotochigova, Svetlana

    2016-01-01

    We study the low-temperature charge transfer reaction between a neutral atom and an ion under the influence of near-resonant laser light. By setting up a multi-channel model with field-dressed states we demonstrate that the reaction rate coefficient can be enhanced by several orders of magnitude with laser intensities of $10^6$ W/cm$^2$ or larger. In addition, depending on laser frequency one can induce a significant enhancement or suppression of the charge-exchange rate coefficient. For our intensities multi-photon processes are not important.

  19. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  20. Ring current proton decay by charge exchange

    Science.gov (United States)

    Smith, P. H.; Hoffman, R. A.; Fritz, T. A.

    1976-01-01

    Explorer 45 (S3-A) measurements were made during the recovery phase of the moderate magnetic storm of February 24, 1972, in which a symmetric ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, which is a consequence of the dissipation of the asymmetric ring current, the equatorially mirroring protons in the energy range 5-30 keV decayed throughout the L value range of 3.5-5.0 at the charge exchange decay rate calculated by Liemohn (1961). After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange is more than sufficient as a particle loss mechanism for the storm time proton ring current decay.

  1. 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)

  2. Strangeness exchange reactions and hypernuclei

    Energy Technology Data Exchange (ETDEWEB)

    Dover, C.B.

    1982-01-01

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

  3. Radiation Reaction for a Charged Brownian Particle

    CERN Document Server

    Vlasov, A A

    2002-01-01

    As it is known a model of a charged particle with finite size is a good tool to consider the effects of self- action and backreaction, caused by electromagnetic radiation. In this work the "size" of a charged particle is induced by its stochastic Brownian vibration. Appropriate equation of particle's motion with radiation force is derived. It is shown that the solutions of this equation correctly describe the effects of radiation reaction.

  4. 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.

  5. Electronic device for measuring the polarization parameter in the {pi}{sup -}p {yields} {pi}{sup 0}n charge exchange reaction on a polarized proton target; Un appareillage electronique destine a la mesure du parametre de polarisation dans la reaction d'echange de charge {pi}{sup -}p {yields} {pi}{sup 0}n sur cible de protons polarises

    Energy Technology Data Exchange (ETDEWEB)

    Brehin, S. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1967-12-15

    An electronic apparatus has been constructed to measure the polarization parameter P{sub 0}(t) in {pi}{sup -}p {yields} {pi}{sup 0}n charge exchange scattering at 5.9 GeV/c and 11,2 GeV/c on polarized proton target. This device insures triggering of a heavy plate spark chamber, allowing visualisation of {gamma} rays from the {pi}{sup 0} decays when the associated neutron offers suitable characteristics in direction and energy. The neutron is detected by an array of 32 counters and his energy is measured by a time of flight method. Electronic circuits of this apparatus are described as test and calibration methods used. (author) [French] Un appareillage electronique a ete realise pour mesurer le parametre de polarisation P{sub 0}(t) dans la reaction d'echange de charge {pi}{sup -}p {yields} {pi}{sup 0}n a 5,9 GeV/c et 11,2 GeV/c sur une cible de protons polarises. Ce dispositif assure le declenchement d'une chambre a etincelles a plaques lourdes, permettant de visualiser les {gamma} de desitegration du {pi}{sup 0}, lorsque le neutron associe presente les caracteristiques convenables en direction et en energie. Le neutron est detecte par un ensemble de 32 compteurs et son energie est mesuree par une methode de temps de vol. Les circuits composant cet appareillage sont decrits ainsi que les methodes d'etalonnage et de verification utilisees. (auteur)

  6. Exchange Reaction Between Selenite and Hydroxyl Ion of Variable Charge Soil Surfaces:I.Electrolyte Species and pH Effects

    Institute of Scientific and Technical Information of China (English)

    ZHOU SHIWEI; ZHANG GANGYA; ZHANG XIAONIAN

    2003-01-01

    Hydroxyl release of red soil and latosol surfaces was quantitatively measured using a self-made constantpH automated titration instrument, to study the changes of hydroxyl release with different added seleniteamounts and pH levels, and to study the effects of electrolytes on hydroxyl release. Hydroxyl release increasedwith the selenite concentration, with a rapid increase at a low selenite concentration while slowing down ata high concentration. The pH where maximum of hydroxyl release appeared was not constant, shifting toa lower valus with increasing selenite concentration. Hydroxyl release decreased with increasing electrolyteconcentration, and the decrease was very rapid at a low electrolyte concentration but slow at a high electrolyteconcentration. For NaC1O4, NaC1 and Na2SO4, hydroxyl release was in the order of NaClO4 > NaCl >Na2SO4, and the difference was very significant. But for NaCl, KCl and CaCl2, the order of hydroxyl releasewas NaCl > KCl > CaCl2, and the difference was smaller. The amount of hydroxyl release from Xuwenlatosol was greater than that from Jinxian red soil. Hydroxyl release existed in a wider range of pH withXuwen latosol than with Jinxian red soil, due to their difference in soil properties. However, both soils hadsimilar curves of hydroxyl release, indicating the common characteristics of variable charge soils.

  7. Nonadiabatic ionic--covalent transitions. Exponential-linear model for the charge exchange and neutralization reactions Na+H arrow-right-left Na/sup +/+H/sup -/

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Mendez, L.; Mo, O.; Riera, A.

    1986-01-01

    A previous study of charge exchange processes taking place through ionic--covalent transitions is extended to the case of Na+H and Na/sup +/+H/sup -/ collisions. A five-state molecular expansion, with the inclusion of two-electron translation factors, is employed to calculate the charge exchange and neutralization cross sections. Transitions at the first two pseudocrossings between the energy curves, practically determine the cross sections in the energy range 0.16--5 keV amu/sup -1/. We also show that the widely used multichannel Landau--Zener theory is totally inadequate, to treat these transitions.

  8. Computational Approach to Electron Charge Transfer Reactions

    DEFF Research Database (Denmark)

    Jónsson, Elvar Örn

    -molecular mechanics scheme, and tools to analyse statistical data and generate relative free energies and free energy surfaces. The methodology is applied to several charge transfer species and reactions in chemical environments - chemical in the sense that solvent, counter ions and substrate surfaces are taken...... in to account - which directly influence the reactants and resulting reaction through both physical and chemical interactions. All methods are though general and can be applied to different types of chemistry. First, the basis of the various theoretical tools is presented and applied to several test systems...... 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...

  9. 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

    2003-06-06

    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.

  10. 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.

  11. Characterization of an atomic hydrogen source for charge exchange experiments

    Science.gov (United States)

    Leutenegger, M. A.; Beiersdorfer, P.; Betancourt-Martinez, G. L.; Brown, G. V.; Hell, N.; Kelley, R. L.; Kilbourne, C. A.; Magee, E. W.; Porter, F. S.

    2016-11-01

    We characterized the dissociation fraction of a thermal dissociation atomic hydrogen source by injecting the mixed atomic and molecular output of the source into an electron beam ion trap containing highly charged ions and recording the x-ray spectrum generated by charge exchange using a high-resolution x-ray calorimeter spectrometer. We exploit the fact that the charge exchange state-selective capture cross sections are very different for atomic and molecular hydrogen incident on the same ions, enabling a clear spectroscopic diagnostic of the neutral species.

  12. Numerical calculation of charge exchange cross sections for plasma diagnostics

    Science.gov (United States)

    Mendez, Luis

    2016-09-01

    The diagnostics of impurity density and temperature in the plasma core in tokamak plasmas is carried out by applying the charge exchange recombination spectroscopy (CXRS) technique, where a fast beam of H atoms collides with the plasma particles leading to electron capture reactions with the impurity ions. The diagnostics is based on the emission of the excited ions formed in the electron capture. The application of the CXRS requires the knowledge of accurate state-selective cross sections, which in general are not accessible experimentally, and the calculation of cross sections for the high n capture levels, required for the diagnostics in the intermediate energy domain of the probe beam, is particularly difficult. In this work, we present a lattice numerical method to solve the time dependent Schrödinger equation. The method is based on the GridTDSE package, it is applicable in the wide energy range 1 - 500 keV/u and can be used to assess the accuracy of previous calculations. The application of the method will be illustrated with calculations for collisions of multiply charged ions with H. Work partially supported by project ENE2014-52432-R (Secretaria de Estado de I+D+i, Spain).

  13. Controlled charge exchange between alkaline earth metals and their ions

    Science.gov (United States)

    Gacesa, Marko; Côté, Robin

    2015-05-01

    We theoretically investigate the prospects of realizing controlled charge exchange via magnetic Feshbach resonances in cold and ultracold collisions of atoms and ions. In particular, we focus on near-resonant charge exchange in heteroisotopic combinations of alkaline earth metals, such as 9Be++10 Be9 Be+10Be+ , which exhibit favorable electronic and hyperfine structure. The quantum scattering calculations are performed for a range of initial states and experimentally attainable magnetic fields in standard coupled-channel Feshbach projection formalism, where higher-order corrections such as the mass-polarization term are explicitely included. In addition, we predict a number of magnetic Feshbach resonances for different heteronuclear isotopic combinations of the listed and related alkaline earth elements. Our results imply that near-resonant charge-exchange could be used to realize atom-ion quantum gates, as well as controlled charge transfer in optically trapped cold quantum gases. This work is partially supported by ARO.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Charge exchange and energy loss of slow highly charged ions in 1 nm thick carbon nanomembranes.

    Science.gov (United States)

    Wilhelm, Richard A; Gruber, Elisabeth; Ritter, Robert; Heller, René; Facsko, Stefan; Aumayr, Friedrich

    2014-04-18

    Experimental charge exchange and energy loss data for the transmission of slow highly charged Xe ions through ultrathin polymeric carbon membranes are presented. Surprisingly, two distinct exit charge state distributions accompanied by charge exchange dependent energy losses are observed. The energy loss for ions exhibiting large charge loss shows a quadratic dependency on the incident charge state indicating that equilibrium stopping force values do not apply in this case. Additional angle resolved transmission measurements point on a significant contribution of elastic energy loss. The observations show that regimes of different impact parameters can be separated and thus a particle's energy deposition in an ultrathin solid target may not be described in terms of an averaged energy loss per unit length.

  19. 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.

  20. A time-resolved study on the interaction of oppositely charged bicelles--implications on the charged lipid exchange kinetics.

    Science.gov (United States)

    Yang, Po-Wei; Lin, Tsang-Lang; Hu, Yuan; Jeng, U-Ser

    2015-03-21

    Time-resolved small-angle X-ray scattering was applied to study charged lipid exchange between oppositely charged disc-shaped bicelles. The exchange of charged lipids gradually reduces the surface charge density and weakens the electrostatic attraction between the oppositely charged bicelles which form alternately stacked aggregates upon mixing. Initially, at a high surface charge density with almost no free water layer between the stacked bicelles, fast exchange kinetics dominate the exchange process. At a later stage with a lower surface charge density and a larger water gap between the stacked bicelles, slow exchange kinetics take over. The fast exchange kinetics are correlated with the close contact of the bicelles when there is almost no free water layer between the tightly bound bicelles with a charged lipid exchange time constant as short as 20-40 min. When the water gap becomes large enough to have a free water layer between the stacked bicelles, the fast lipid exchange kinetics are taken over by slow lipid exchange kinetics with time constants around 200-300 min, which are comparable to the typical time constant of lipid exchange between vesicles in aqueous solution. These two kinds of exchange mode fit well with the lipid exchange models of transient hemifusion for the fast mode and monomer exchange for the slow mode.

  1. Solid state exchange reactions and thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Albarran, G.; Archundia, C.; Maddock, A.G.

    1982-01-01

    A further study of exchange of the cobalt atoms in solid Co(H/sub 2/O)/sub 6/(Co EDTA)/sub 2/ x 4H/sub 2/O has been made. The exchange is more easily measured when the compound has been ..gamma.. irradiated before heating. Without irradiation the exchange is complicated by substantial concurrent thermal decomposition. Vacuum dehydration to the tetrahydrate can be effected at 366 K without appreciable exchange. A relation between exchange, annealing of radiolytic decomposition and thermal decomposition in such compounds is suggested.

  2. 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…

  3. Inclusive double-charge-exchange. pi. /sup -/ production at 100 GeV/c

    Energy Technology Data Exchange (ETDEWEB)

    Cutts, D.; Dulude, R.; Lanou, R.E.; Massimo, J.T.; Meunier, R.; Brenner, A.E.; Carey, D.C.; Elias, J.E.; Garbincius, P.H.; Mikenberg, G.; Polychronakos, V.A.; Weitsch, G.A.; Chiaradia, M.T.; DeMarzo, C.; Favuzzi, C.; Germinario, G.; Guerriero, L.; Lavopa, P.; Maggi, G.; Posa, F.; Selvaggi, G.; Spinelli, P.; Waldner, F.; Aitkenhead, W.; Barton, D.S.; Brandenburg, G.; Busza, W.; Dobrowolski, T.; Friedman, J.I.; Kendall, H.W.; Lyons, T.; Nelson, B.; Rosenson, L.; Toy, W.; Verdier, R.; Votta, L.

    1978-01-16

    Measurements of inclusive cross sections at 100 GeV/c are presented for the double-charge-exchange reactions a/sup +/p ..-->.. ..pi../sup -/X with a = ..pi.., K, or p. The measurements covered a kinematic range in the Feynman x variable of 0.3 < or = x < or = 0.9 at transverse momenta of 0.3 and 0.5 GeV/c. A model summing the contributions from resonance production and from inclusive central-region ..pi../sup -/ 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.

  4. Significant enhancement of the charging efficiency in the cavities of ferroelectrets through gas exchange during charging

    Science.gov (United States)

    Qiu, Xunlin

    2016-11-01

    Ferroelectrets are non-polar polymer foams or polymer systems with internally charged cavities. They are charged through a series of dielectric barrier discharges (DBDs) that are caused by the electrical breakdown of the gas inside the cavities. Thus, the breakdown strength of the gas strongly influences the charging process of ferroelectrets. A gas with a lower breakdown strength has a lower threshold voltage, thus decreasing the onset voltage for DBD charging. However, a lower threshold voltage also leads to a lower value for the remanent polarization, as back discharges that are caused by the electric field of the internally deposited charges can take place already at lower charge levels. On this basis, a charging strategy is proposed where the DBDs start in a gas with a lower breakdown strength (in the present example, helium) and are completed at a higher breakdown strength (e.g., nitrogen or atmospheric air). Thus, the exchange of the gas in the cavities during charging can significantly enhance the charging efficiency, i.e., yield much higher piezoelectric coefficients in ferroelectrets at significantly lower charging voltages.

  5. Imaging charge exchange recombination spectroscopy on the TEXTOR tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Howard, J [Plasma Research Laboratory, The Australian National University, Canberra 0200 (Australia); Jaspers, R [Eindhoven University of Technology, Eindhoven (Netherlands); Lischtschenko, O; Delabie, E [FOM Institute for Plasma Physics ' Rijnhuizen' , Nieuwegein (Netherlands); Chung, J [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2010-12-15

    We describe the application of a simple spatial-heterodyne coherence-imaging filter for 2D Doppler imaging of charge exchange recombination (CXR) emission from a heating beam in the TEXTOR tokamak. Results obtained by the CXR imaging system are found to be consistent with measurements obtained using a standard multi-channel spectrometer-based system. We describe the system, indicate possible enhancements and future applications for imaging CXRS.

  6. Imaging charge exchange recombination spectroscopy on the TEXTOR tokamak

    Science.gov (United States)

    Howard, J.; Jaspers, R.; Lischtschenko, O.; Delabie, E.; Chung, J.

    2010-12-01

    We describe the application of a simple spatial-heterodyne coherence-imaging filter for 2D Doppler imaging of charge exchange recombination (CXR) emission from a heating beam in the TEXTOR tokamak. Results obtained by the CXR imaging system are found to be consistent with measurements obtained using a standard multi-channel spectrometer-based system. We describe the system, indicate possible enhancements and future applications for imaging CXRS.

  7. Systematics of heavy-ion charge-exchange straggling

    Science.gov (United States)

    Sigmund, P.; Schinner, A.

    2016-10-01

    The dependence of heavy-ion charge-exchange straggling on the beam energy has been studied theoretically for several ion-target combinations. Our previous work addressed ions up to krypton, while the present study focuses on heavier ions, especially uranium. Particular attention has been paid to a multiple-peak structure which has been predicted theoretically in our previous work. For high-Z1 and high-Z2 systems, exemplified by U in Au, we identify three maxima in the energy dependence of charge-exchange straggling, while the overall magnitude is comparable with that of collisional straggling. Conversely, for U in C, charge-exchange straggling dominates, but only two peaks lie in the energy range where we presently are able to produce credible predictions. For U-Al we find good agreement with experiment in the energy range around the high-energy maximum. The position of the high-energy peak - which is related to processes in the projectile K shell - is found to scale as Z12 , in contrast to the semi-empirical Z13/2 dependence proposed by Yang et al. Measurements for heavy ions in heavy targets are suggested in order to reconcile a major discrepancy between the present calculations and the frequently-used formula by Yang et al.

  8. 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 (...

  9. Interdefect charge exchange in silicon particle detectors at cryogenic temperatures

    CERN Document Server

    MacEvoy, B; Hall, G; Moscatelli, F; Passeri, D; Santocchia, A

    2002-01-01

    Silicon particle detectors in the next generation of experiments at the CERN Large Hadron Collider will be exposed to a very challenging radiation environment. The principal obstacle to long-term operation arises from changes in detector doping concentration (N/sub eff/), which lead to an increase in the bias required to deplete the detector and hence achieve efficient charge collection. We have previously presented a model of interdefect charge exchange between closely spaced centers in the dense terminal clusters formed by hadron irradiation. This manifestly non-Shockley-Read-Hall (SRH) mechanism leads to a marked increase in carrier generation rate and negative space charge over the SRH prediction. There is currently much interest in the subject of cryogenic detector operation as a means of improving radiation hardness. Our motivation, however, is primarily to investigate our model further by testing its predictions over a range of temperatures. We present measurements of spectra from /sup 241/Am alpha par...

  10. Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction

    Science.gov (United States)

    Binitha, N. N.; Silija, P. P.; Suraj, V.; Yaakob, Z.; Sugunan, S.

    2011-02-01

    Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using Temperature Programmed Desorption (TPD) of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Brønsted acidity is confirmed from high selectivity to benzene.

  11. Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Binitha, N N; Silija, P P; Yaakob, Z [Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, National University of Malaysia, 43600 UKM Bangi, Selangor (Malaysia); School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibah, 02600, Jejawi, Perlis (Malaysia); Suraj, V [Department of Applied Chemistry, CUSAT, Cochin 22, Kerala (India); Sugunan, S, E-mail: binithann@yahoo.co.in [National Institute of Technology, Calicut, Kerala (India)

    2011-02-15

    Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using Temperature Programmed Desorption (TPD) of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Broensted acidity is confirmed from high selectivity to benzene.

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

    Energy Technology Data Exchange (ETDEWEB)

    Seidl, P.A.

    1985-02-01

    Cross sections for the /sup 13,14/C,/sup 26/Mg,/sup 56/Fe(..pi../sup +/,..pi../sup -/)/sup 13,14/O,/sup 26/Si,/sup 56/Ni 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 ..pi../ 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 /sup 14/O(0/sup +/, 5.92 MeV), /sup 14/O(2/sup +/, 7.77 MeV), /sup 56/Ni(gs), /sup 13/O(gs), and /sup 13/O(4.21 MeV) are presented. The /sup 13/O(4.21 MeV) state is postulated to have J/sup ..pi../ = 1/2/sup -/. 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 ..delta../sub 33/ 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 ..pi../ > 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.

  13. 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.

  14. Charged and Neutral Current Neutrino Induced Nucleon Emission Reactions

    CERN Document Server

    Nieves, J; Vacas, M J V

    2006-01-01

    By means of a Monte Carlo cascade method, to account for the rescattering of the outgoing nucleon, we study the charged and neutral current inclusive one nucleon knockout reactions off nuclei induced by neutrinos. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, and can be used in the analysis of future neutrino experiments.

  15. Cu Vacancies Boost Cation Exchange Reactions in Copper Selenide Nanocrystals.

    Science.gov (United States)

    Lesnyak, Vladimir; Brescia, Rosaria; Messina, Gabriele C; Manna, Liberato

    2015-07-29

    We have investigated cation exchange reactions in copper selenide nanocrystals using two different divalent ions as guest cations (Zn(2+) and Cd(2+)) and comparing the reactivity of close to stoichiometric (that is, Cu2Se) nanocrystals with that of nonstoichiometric (Cu(2-x)Se) nanocrystals, to gain insights into the mechanism of cation exchange at the nanoscale. We have found that the presence of a large density of copper vacancies significantly accelerated the exchange process at room temperature and corroborated vacancy diffusion as one of the main drivers in these reactions. Partially exchanged samples exhibited Janus-like heterostructures made of immiscible domains sharing epitaxial interfaces. No alloy or core-shell structures were observed. The role of phosphines, like tri-n-octylphosphine, in these reactions, is multifaceted: besides acting as selective solvating ligands for Cu(+) ions exiting the nanoparticles during exchange, they also enable anion diffusion, by extracting an appreciable amount of selenium to the solution phase, which may further promote the exchange process. In reactions run at a higher temperature (150 °C), copper vacancies were quickly eliminated from the nanocrystals and major differences in Cu stoichiometries, as well as in reactivities, between the initial Cu2Se and Cu(2-x)Se samples were rapidly smoothed out. These experiments indicate that cation exchange, under the specific conditions of this work, is more efficient at room temperature than at higher temperature.

  16. 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.

  17. Carbonyl-Olefin Exchange Reaction and Related Chemistry

    Science.gov (United States)

    Jossifov, Christo; Kalinova, Radostina

    A new carbon—carbon double bond forming reaction (carbonyl olefin exchange reaction) mediated by transition metal catalytic systems has been discovered. The catalytic systems used (transition metal halides or oxohalides alone or in combination with Lewis acids) are active only in the case when the two reacting groups are in one molecules and are conjugated. In addition these systems accelerate other reactions which run simultaneously with the carbonyl olefin metathesis rendering a detailed investigation of the process very complicated.

  18. 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.

  19. Molecular (Feshbach) treatment of charge exchange Li/sup 3 +/+He collisions. II. Cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Errea, L.F.; Martin, F.; Mendez, L.; Riera, A.; Yanez, M.

    1986-05-15

    Using the wave functions calculated in the preceding article, and a common translation factor, the charge exchange cross section for the Li/sup 3 +/+He(1s/sup 2/) reaction is calculated, and the mechanism of the process discussed. We show how small deviations from the Landau--Zener model, which are unrelated to Nikitin's conditions for its validity, lead to a minimum of the cross section at an impact energy Eapprox. =1 keV, and to larger values of sigma at intermediate nuclear velocities.

  20. 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 ...

  1. 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.

  2. 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...

  3. Improved edge charge exchange recombination spectroscopy in DIII-D

    Science.gov (United States)

    Chrystal, C.; Burrell, K. H.; Grierson, B. A.; Haskey, S. R.; Groebner, R. J.; Kaplan, D. H.; Briesemeister, A.

    2016-11-01

    The charge exchange recombination spectroscopy diagnostic on the DIII-D tokamak has been upgraded with the addition of more high radial resolution view chords near the edge of the plasma (r/a > 0.8). The additional views are diagnosed with the same number of spectrometers by placing fiber optics side-by-side at the spectrometer entrance with a precise separation that avoids wavelength shifted crosstalk without the use of bandpass filters. The new views improve measurement of edge impurity parameters in steep gradient, H-mode plasmas with many different shapes. The number of edge view chords with 8 mm radial separation has increased from 16 to 38. New fused silica fibers have improved light throughput and clarify the observation of non-Gaussian spectra that suggest the ion distribution function can be non-Maxwellian in low collisionality plasmas.

  4. Charge Exchange Cross Sections Measured at Low Energies in Q-Machines

    DEFF Research Database (Denmark)

    Andersen, S. A.; Jensen, Vagn Orla; Michelsen, Poul

    1972-01-01

    A new technique for measurements of charge exchange cross sections at low energies is described. The measurements are performed in a single‐ended Q machine. The resonance charge exchange cross section for Cs at 2 eV was found to be 0.6×10−13 cm2±20%.......A new technique for measurements of charge exchange cross sections at low energies is described. The measurements are performed in a single‐ended Q machine. The resonance charge exchange cross section for Cs at 2 eV was found to be 0.6×10−13 cm2±20%....

  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. 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

  7. Photoinduced charge separation and enzyme reactions in reversed micelles.

    NARCIS (Netherlands)

    Verhaert, R.M.D.

    1989-01-01

    In this thesis the performance and coupling of two types of reaction, photoinduced charge separation and enzymatic conversion were studied in reversed micelles. Reversed micelles are 1 to 10 nm sized water droplets dispersed in an organic solution. The dispersant is a detergent (cationogenic, nonion

  8. 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 ...

  9. XMM-Newton Observations of Solar Wind Charge Exchange Emission

    Science.gov (United States)

    Snowden, S. L.; Collier, M. R.; Kuntz, K. D.

    2004-01-01

    We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by O VII and O VIII lines at 0.57 keV and 0.65 keV, O VIII (and possibly Fe XVII) lines at approximately 0.8 keV, Ne IX lines at approximately 0.92 keV, and Mg XI lines at approximately 1.35 keV. This spectrum is consistent with what is expected from charge exchange emission between the highly ionized solar wind and either interstellar neutrals in the heliosphere or material from Earth's exosphere. The emission is clearly seen as a low-energy ( E less than 1.5 keV) spectral enhancement in one of a series of observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by the ACE satellite. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has ion ratios with significantly enhanced higher ionization states. Whereas observations of the solar wind plasma made at a single point reflect only local conditions which may only be representative of solar wind properties with spatial scales ranging from less than half of an Earth radii (approximately 10 s) to 100 Earth radii, X-ray observations of solar wind charge exchange are remote sensing measurements which may provide observations which are significantly more global in character. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of more cosmological objects. It can provide emission lines at zero redshift which are of particular interest (e.g., O VII and O VIII) in studies of diffuse thermal emission, and which can therefore act as contamination in objects which cover the entire detector field of view. We propose the use of solar wind monitoring data, such as from the ACE and Wind spacecraft, as a diagnostic to screen for such possibilities.

  10. 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.

  11. Geometric phase effects in ultracold hydrogen exchange reaction

    Science.gov (United States)

    Hazra, Jisha; Kendrick, Brian K.; Balakrishnan, N.

    2016-10-01

    The role of the geometric phase effect on chemical reaction dynamics is explored by examining the hydrogen exchange process in the fundamental H+HD reaction. Results are presented for vibrationally excited HD molecules in the v = 4 vibrational level and for collision energies ranging from 1 μK to 100 K. It is found that, for collision energies below 3 K, inclusion of the geometric phase leads to dramatic enhancement or suppression of the reaction rates depending on the final quantum state of the HD molecule. The effect was found to be the most prominent for rotationally resolved integral and differential cross sections but it persists to a lesser extent in the vibrationally resolved and total reaction rate coefficients. However, no significant GP effect is present in the reactive channel leading to the D+H2 product or in the D+H2 (v=4,j=0) \\to HD+H reaction. A simple interference mechanism involving inelastic (nonreactive) and exchange scattering amplitudes is invoked to account for the observed GP effects. The computed results also reveal a shape resonance in the H+HD reaction near 1 K and the GP effect is found to influence the magnitude of the resonant part of the cross section. Experimental detection of the resonance may allow a sensitive probe of the GP effect in the H+HD reaction.

  12. Spin Dependence in Neutron-Proton Charge Exchange at 790 MeV

    Science.gov (United States)

    Ransome, R. D.; Hollas, C. L.; Riley, P. J.; Bonner, B. E.; Gibbs, W. R.; McNaughton, M. W.; Simmons, J. E.; Bhatia, T. S.; Glass, G.; Hiebert, J. C.; Northcliffe, L. C.; Tippens, W. B.

    1982-03-01

    The analyzing power A and spin-transfer parameters KNN, KSS, KSL, and KLL have been measured in the np charge-exchange (np-->pn) region at 790 MeV. These data provide new and unique information on the spin dependence of the np interaction in the charge-exchange region. Models which explain the charge-exchange peak in the np elastic differential cross section as being due to interference between one-pion exchange and a slowly varying background are in basic agreement with the data.

  13. 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.

  14. 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,...

  15. Charge exchange spectroscopy as a fast ion diagnostic on TEXTORa)

    Science.gov (United States)

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

    2008-10-01

    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 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 Dα spectrum while the beam emission spectrum is Doppler shifted to the red wing. An analysis combining the two 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 with a spectral model for the slowing down feature. The analysis of the fast ion Dα spectrum obtained with the new diagnostic is discussed.

  16. Carbonyl-Olefin Exchange Reaction: Present State and Outlook

    Science.gov (United States)

    Kalinova, Radostina; Jossifov, Christo

    The carbonyl-olefin exchange reaction (COER) is a new reaction between carbonyl group and olefin double bond, which has a formal similarity with the olefin metathesis (OM) - one carbon atom in the latter is replaced with an oxygen atom. Till now the new reaction is performed successfully only when the two functional groups (carbonyl group and olefin double bond) are in one molecule and are conjugated. The α, β-unsaturated carbonyl compounds (substituted propenones) are the compounds with such a structure. They polymerize giving substituted polyacetylenes. The chain propagation step of this polymerization is in fact the COER. The question arises: is it possible the COER to take place when the two functional groups are not in one molecule and are not conjugated, and could this reaction became an alternative of the existing carbonyl olefination reactions?

  17. 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.

  18. Charge density asymmetry of heavy-ion fusion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Poenaru, N.D.; Ivascu, M.; Mazilu, D.; Sandulescu, A. (Institutul de Fizica si Inginerie Nucleara, Bucharest (Romania))

    1980-01-01

    The generalized liquid-drop model replacing surface energy by double folded Yukawa-plus-exponential function is extended for fusion of heavy ions with different charge densities. Calculated interaction barriers for some 58 pairs of nuclei are in good agreement with experimental ones, within -10% and +7%. For even-even beta-stable nuclei with Z =4-104 the general trend of variation of interaction barriers and fusion Q-values show the regions where the charge density asymmetry cannot be neglected. PES for the entrance channel of the reactions /sup 109/Ag + /sup 40/Ar, /sup 138/Ce + /sup 57/Fe, /sup 144/Nd + /sup 84/Kr and the corresponding charge-equilibrated system have been computed.

  19. 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.

  20. Base initiated halogen-exchange reactions between perhaloalkanes

    Institute of Scientific and Technical Information of China (English)

    傅伟敏; 李兴亚; 蒋锡夔

    1997-01-01

    Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of among molecules of the same compound It provides a new and convenient method to synthesize perhaloal-kanes Apparently,it pertains to an amomc mechanism,i e.the reaction is initiated by halophilic attack on C-X bonds by the base,and an intermediate carbanion is formed.Distributions of the products depend on the equilibria involving all carbanion intermediates and perhaloalkane product molecules.

  1. Separation of the isotopes of boron by chemical exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    McCandless, F.P.; Herbst, R.S.

    1995-05-30

    The isotopes of boron, {sup 10}B and {sup 11}B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF{sub 3} and a liquid BF{sub 3} donor molecular addition complex formed between BF{sub 3} gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone. 1 Fig.

  2. 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.

  3. First Demonstration of Laser-Assisted Charge Exchange for Microsecond Duration H- Beams

    Science.gov (United States)

    Cousineau, Sarah; Rakhman, Abdurahim; Kay, Martin; Aleksandrov, Alexander; Danilov, Viatcheslav; Gorlov, Timofey; Liu, Yun; Plum, Michael; Shishlo, Andrei; Johnson, David

    2017-02-01

    This Letter reports on the first demonstration of laser-assisted H- charge exchange for microsecond duration H- beam pulses. Laser-assisted charge exchange injection is a breakthrough technology that overcomes long-standing limitations associated with the traditional method of producing high intensity, time structured beams of protons in accelerators via the use of carbon foils for charge exchange injection. The central theme of this experiment is the demonstration of novel techniques that reduce the laser power requirement to allow high efficiency stripping of microsecond duration beams with commercial laser technology.

  4. 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

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

    Science.gov (United States)

    Gu, Liyi; Kaastra, Jelle; Raassen, A. J. J.

    2016-04-01

    Charge exchange X-ray emission provides unique insight 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 have created a new spectral code to evaluate the charge exchange emission in the X-ray band. Compared 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 exchange model will allow us to probe the ion properties remotely, including charge state, dynamics, and composition, at the interface between the cold and hot plasmas.

  6. Conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center

    DEFF Research Database (Denmark)

    Katona, Gergely; Snijder, Arjan; Gourdon, Pontus Emanuel;

    2005-01-01

    In bright light the photosynthetic reaction center (RC) of Rhodobacter sphaeroides stabilizes the P(+)(870).Q(-)(A) charge-separated state and thereby minimizes the potentially harmful effects of light saturation. Using X-ray diffraction we report a conformational change that occurs within the cy...

  7. Recent Excitation, Charge Exchange, and Lifetime Results in Highly Charged Ions Relevant to Stellar, Interstellar, Solar and Comet Phenomena

    Science.gov (United States)

    Chutjian, A.; Hossain, S.; Mawhorter, R. J.; Smith, S. J.

    2006-01-01

    Recent JPL absolute excitation and charge exchange cross sections, and measurements of lifetimes of metastable levels in highly-charged ions (HCIs) are reported. These data provide benchmark comparisons to results of theoretical calculations. Theoretical approaches can then be used to calculate the vast array of data which cannot be measured due to experimental constraints. Applications to the X-ray emission from comets are given.

  8. 78 FR 6263 - Exchange Visitor Program-Fees and Charges

    Science.gov (United States)

    2013-01-30

    ... educational and cultural exchanges to be a significant part of the public diplomacy efforts of the President... Order. The Department has examined the economic benefits, costs, and transfers associated with this... diplomacy and an integral component of American foreign policy. The benefits of these exchanges to...

  9. Solar Wind Charge Exchange and O VIII emission toward MBM 12

    Science.gov (United States)

    Edgar, Richard J.; Wargelin, B. J.; Raymond, J. C.; Slavin, J. D.; Smith, R. K.; Kharchenko, V.

    2006-09-01

    A Chandra observation toward MBM-12, a nearby (MBM 12 during the Chandra observation. The Solar Wind Charge Exchange mechanism can account for essentially all of the O VIII emission seen in this observation.

  10. EXFOR systems manual: Nuclear reaction data exchange format

    Energy Technology Data Exchange (ETDEWEB)

    McLane, V. [ed.

    1996-07-01

    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).

  11. A compilation of charged-particle induced thermonuclear reaction rates

    CERN Document Server

    Angulo, C; Rayet, M; Descouvemont, P; Baye, D; Leclercq-Willain, C; Coc, A; Barhoumi, S; Aguer, P; Rolfs, C; Kunz, R; Hammer, J W; Mayer, A; Paradelis, T; Kossionides, S; Chronidou, C; Spyrou, K; Degl'Innocenti, S; Fiorentini, G; Ricci, B; Zavatarelli, S; Providência, C; Wolters, H; Soares, J; Grama, C; Rahighi, J; Shotter, A; Rachti, M L

    1999-01-01

    Low-energy cross section data for 86 charged-particle induced reactions involving light (1 <= Z <= 14), mostly stable, nuclei are compiled. The corresponding Maxwellian-averaged thermonuclear reaction rates of relevance in astrophysical plasmas at temperatures in the range from 10 sup 6 K to 10 sup 1 sup 0 K are calculated. These evaluations assume either that the target nuclei are in their ground state, or that the target states are thermally populated following a Maxwell-Boltzmann distribution, except in some cases involving isomeric states. Adopted values complemented with lower and upper limits of the rates are presented in tabular form. Analytical approximations to the adopted rates, as well as to the inverse/direct rate ratios, are provided.

  12. A compilation of charged-particle induced thermonuclear reaction rates

    Energy Technology Data Exchange (ETDEWEB)

    Angulo, C.; Arnould, M.; Rayet, M.; Descouvemont, P.; Baye, D.; Leclercq-Willain, C.; Coc, A.; Barhoumi, S.; Aguer, P.; Rolfs, C.; Kunz, R.; Hammer, J.W.; Mayer, A.; Paradellis, T.; Kossionides, S.; Chronidou, C.; Spyrou, K.; Degl' Innocenti, S.; Fiorentini, G.; Ricci, B.; Zavatarelli, S.; Providencia, C.; Wolters, H.; Soares, J.; Grama, C.; Rahighi, J.; Shotter, A.; Rachti, M. Lamehi

    1999-08-23

    Low-energy cross section data for 86 charged-particle induced reactions involving light (1 {<=} Z {<=} 14), mostly stable, nuclei are compiled. The corresponding Maxwellian-averaged thermonuclear reaction rates of relevance in astrophysical plasmas at temperatures in the range from 10{sup 6} K to 10{sup 10} K are calculated. These evaluations assume either that the target nuclei are in their ground state, or that the target states are thermally populated following a Maxwell-Boltzmann distribution, except in some cases involving isomeric states. Adopted values complemented with lower and upper limits of the rates are presented in tabular form. Analytical approximations to the adopted rates, as well as to the inverse/direct rate ratios, are provided.

  13. Computation of charged current neutrino-Te reactions cross sections

    Science.gov (United States)

    Tsakstara, V.; Kosmas, T. S.; Sinatkas, J.

    2016-08-01

    Neutrino-nucleus reactions, involving both neutral current (NC) and charged current (CC) interactions are important probes in modern neutrino physics searches. In the present work, we study the concrete CC reactions 130 Te(vℓ,ℓ-)130 I and 130 Te(ṽℓ,ℓ+)130Sb which are of current experimental interest for the CUORE and COBRA experiments operating at Gran Sasso underground laboratory in Italy. The nuclear wave functions for the required initial and final nuclear states are derived by employing the proton-neutron (p-n) quasi-particle random phase approximation (QRPA) which has been previously tested in our neutral-current v-nucleus studies for Te isotopes.

  14. 78 FR 28137 - Exchange Visitor Program-Fees and Charges

    Science.gov (United States)

    2013-05-14

    .... The Department has examined the economic benefits, costs, and transfers associated with this rule, and declares that educational and cultural exchanges are both cornerstones of U.S. public diplomacy and...

  15. Population of 13Be in a Nucleon Exchange Reaction

    CERN Document Server

    Marks, B R; Smith, J K; Baumann, T; Brown, J; Frank, N; Hinnefeld, J; Hoffman, M; Jones, M D; Kohley, Z; Kuchera, A N; Luther, B; Spyrou, A; Stephenson, S; Sullivan, C; Thoennessen, M; Viscariello, N; Williams, S J

    2015-01-01

    The neutron-unbound nucleus 13Be was populated with a nucleon-exchange reaction from a 71 MeV/u secondary 13B beam. The decay energy spectrum was reconstructed using invariant mass spectroscopy based on 12Be fragments in coincidence with neutrons. The data could be described with an s-wave resonance at E = 0.73(9) MeV with a width of Gamma = 1.98(34) MeV and a d-wave resonance at E = 2.56(13) MeV with a width of Gamma = 2.29(73) MeV. The observed spectral shape is consistent with previous one-proton removal reaction measurements from 14B.

  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.

  17. Charge ordering and exchange bias behaviors in Co3O4 porous nanoplatelets and nanorings

    Science.gov (United States)

    Debnath, J. C.; Wang, Jianli; Zeng, R.

    2017-01-01

    We present the synthesis of α-Co3O4 porous nanoplatelets and hexagonal nanorings using microwave-assisted hydrothermal and conventional chemical reaction methods. The x-ray diffraction (XRD) and refinement analyses indicate the α-Co3O4 crystal structure, and the x-ray photoelectron spectrum (XPS) indicates the high purity of the samples. The M-T (including 1/χ-T) curves indicate an antiferromagnetic transition at about 35 K in both kind of samples but the interesting finding was made that a charge-ordered (CO) state appears at 250 K for the nanoplatelets sample whereas it is inattentive for the nanorings. The antiferromagnetic transition temperature TN is lower than that of the bulk α-Co3O4 single crystal due to the nanosized structures. We observed quite significant exchange bias for nanorings. The exchange bias behavior of the α-Co3O4 hexagonal nanorings is consistent with an antiferromagnetic (AFM) Co3O4 core and spin-glass like shell.

  18. Alloyed copper chalcogenide nanoplatelets via partial cation exchange reactions.

    Science.gov (United States)

    Lesnyak, Vladimir; George, Chandramohan; Genovese, Alessandro; Prato, Mirko; Casu, Alberto; Ayyappan, S; Scarpellini, Alice; Manna, Liberato

    2014-08-26

    We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide-sulfide (CZSeS), copper tin selenide-sulfide (CTSeS), and copper zinc tin selenide-sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide-sulfide (Cu2-xSeyS1-y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2-xSeyS1-y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV-vis-NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps.

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

    Energy Technology Data Exchange (ETDEWEB)

    McLane, V.

    1996-07-01

    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.

  20. 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.

  1. 76 FR 10498 - Exchange Visitor Program-Fees and Charges

    Science.gov (United States)

    2011-02-25

    ... as sponsors of an exchange visitor program, designated as such to further the public diplomacy... Department has determined that this rule will not have a significant economic impact on a substantial number... Department has examined the economic benefits, costs, and transfers associated with this final rule,...

  2. Inclusive Charged--Current Neutrino--Nucleus Reactions

    CERN Document Server

    Nieves, J; Vacas, M J Vicente

    2011-01-01

    We present a model for weak CC induced nuclear reactions at energies of interest for current and future neutrino oscillation experiments. This model is a natural extension of the work of Refs.[1,2], where the QE contribution to the inclusive electron and neutrino scattering on nuclei was analyzed. The model is based on a systematic many body expansion of the gauge boson absorption modes that includes one, two and even three body mechanisms, as well as the excitation of Delta isobars. The whole scheme has no free parameters, besides those previously adjusted to the weak pion production off the nucleon cross sections in the deuteron, since all nuclear effects were set up in previous studies of photon, electron and pion interactions with nuclei. We have discussed at length the recent charged current quasi-elastic MiniBooNE cross section data, and showed that two nucleon knockout mechanisms are essential to describe these measurements.

  3. Charge transfer reactions at interfaces between neutral gas and plasma: Dynamical effects and X-ray emission

    Science.gov (United States)

    Provornikova, E.; Izmodenov, V. V.; Lallement, R.

    2012-04-01

    Charge-transfer is the main process linking neutrals and charged particles in the interaction regions of neutral (or partly ionized) gas with a plasma. In this paper we illustrate the importance of charge-transfer with respect to the dynamics and the structure of neutral gas-plasma interfaces. We consider the following phenomena: (1) the heliospheric interface - region where the solar wind plasma interacts with the partly-ionized local interstellar medium (LISM) and (2) neutral interstellar clouds embedded in a hot, tenuous plasma such as the million degree gas that fills the so-called ``Local Bubble". In (1), we discuss several effects in the outer heliosphere caused by charge exchange of interstellar neutral atoms and plasma protons. In (2) we describe the role of charge exchange in the formation of a transition region between the cloud and the surrounding plasma based on a two-component model of the cloud-plasma interaction. In the model the cloud consists of relatively cold and dense atomic hydrogen gas, surrounded by hot, low density, fully ionized plasma. We discuss the structure of the cloud-plasma interface and the effect of charge exchange on the lifetime of interstellar clouds. Charge transfer between neutral atoms and minor ions in the plasma produces X-ray emission. Assuming standard abundances of minor ions in the hot gas surrounding the cold interstellar cloud, we estimate the X-ray emissivity consecutive to the charge transfer reactions. Our model shows that the charge-transfer X-ray emission from the neutral cloud-plasma interface may be comparable to the diffuse thermal X-ray emission from the million degree gas cavity itself.

  4. Charge-exchange scattering to the isobaric analog state at medium energies as a probe of the neutron skin

    CERN Document Server

    Loc, Bui Minh; Zegers, R G T

    2014-01-01

    The charge-exchange (3He,t) scattering to the isobaric analog state (IAS) of the target can be considered as "elastic" scattering of 3He by the isovector term of the optical potential (OP) that flips the projectile isospin. Therefore, the accurately measured charge-exchange scattering cross- section for the IAS can be a good probe of the isospin dependence of the OP, which is determined exclusively within the folding model by the difference between the neutron and proton densities and isospin dependence of the nucleon-nucleon interaction. Given the neutron skin of the target is related directly to the same density difference, it can be well probed in the analysis of the charge- exchange (3He,t) reactions at medium energies when the two-step processes can be neglected and the t-matrix interaction can be used in the folding calculation. For this purpose, the data of the (3He,t) scattering to the IAS of 90Zr and 208Pb targets at Elab = 420 MeV have been analyzed in the distorted wave Born approximation using the...

  5. Location of DNA damage by charge exchanging repair enzymes: effects of cooperativity on location time

    Directory of Open Access Journals (Sweden)

    Eriksen Kasper

    2005-04-01

    Full Text Available Abstract Background How DNA repair enzymes find the relatively rare sites of damage is not known in great detail. Recent experiments and molecular data suggest that individual repair enzymes do not work independently of each other, but interact with each other through charges exchanged along the DNA. A damaged site in the DNA hinders this exchange. The hypothesis is that the charge exchange quickly liberates the repair enzymes from error-free stretches of DNA. In this way, the sites of damage are located more quickly; but how much more quickly is not known, nor is it known whether the charge exchange mechanism has other observable consequences. Results Here the size of the speed-up gained from this charge exchange mechanism is calculated and the characteristic length and time scales are identified. In particular, for Escherichia coli, I estimate the speed-up is 50000/N, where N is the number of repair enzymes participating in the charge exchange mechanism. Even though N is not exactly known, a speed-up of order 10 is not entirely unreasonable. Furthermore, upon over expression of all the repair enzymes, the location time only varies as N-1/2 and not as 1/N. Conclusion The revolutionary hypothesis that DNA repair enzymes use charge exchange along DNA to locate damaged sites more efficiently is actually sound from a purely theoretical point of view. Furthermore, the predicted collective behavior of the location time is important in assessing the impact of stress-ful and radioactive environments on individual cell mutation rates.

  6. An anomaly in inclusive pion double charge exchange on {sup 16}O at about 1 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, B.M.; Bulychjov, S.A.; Dukhovskoy, I.A. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)] [and others

    1996-11-01

    The new results on the inclusive double charge exchange (DCX) reaction {sup 16}O({pi}{sup -}, {pi}{sup +})X at incident kinetic energy T{sub o} = 0.75 and 1.15 GeV are presented. The data were taken without using Cherenkov counters. The new DCX cross sections agree well with the old ones. Both the values are about an order of magnitude larger than the theoretical cross section calculated for the standard sequential mechanism. Two other approaches which seem to explain the discrepancy are also briefly reviewed. (author) 9 refs, 3 figs

  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(-).

  8. Theoretical study of charge exchange dynamics in He$^+$ + NO collisions

    CERN Document Server

    Bene, E

    2014-01-01

    We investigate the charge transfer mechanism in the collisions of helium ions on nitric oxide using a molecular description framework with consideration of the orientation of the projectile toward the target. The anisotropy of the collision process has been analysed in detail in connection with the non-adiabatic interactions around avoided crossings. Potential energy curves, radial and rotational coupling matrix elements have been determined by means of ab initio quantum chemical methods. The collision dynamics is performed in the [1.-25.] keV collision energy range using a semiclassical approach, and the total electron transfer cross sections are analysed with regard to available experimental data.

  9. Computational Investigation and Hydrogen/Deuterium Exchange of the Fixed Charge Derivative Tris(2,4,6-Trimethoxyphenyl)Phosphonium: Implications for the Aspartic Acid Cleavage Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, Kristin A.; Wysocki, Vicki H.; Vorpagel, Erich R.

    2005-05-25

    Aspartic acid (Asp)-containing peptides with the fixed charge derivative tris(2,4,6-trimethoxyphenyl) phosphonium (tTMP-P+) were explored computationally and experimentally by H/D exchange and fragmentation studies in order to probe the phenomenon of selective cleavage C-terminal to Asp in the absence of a ''mobile'' proton. Ab initio modeling of the tTMP-P+ electrostatic potential demonstrates the positive charge is distributed on the phosphonium group and therefore is not initiating or directing fragmentation as would a ''mobile'' proton. Geometry optimizations and vibrational analyses of different aspartic acid conformations show the aspartic acid structure with a hydrogen bond between the side chain hydroxy and backbone carbonyl lies 2.8 kcal/mol above the lowest energy conformer. In reactions with D2O, the phosphonium-derived doubly charged peptide (H+)P+LDIFSDF rapidly exchanges all 12 of its exchangeable hydrogens for deuterium and also displays a non-exchanging population. With no added proton, P+LDIFSDF exchanges a maximum of four of eleven exchangeable hydrogens for deuterium. No exchange is observed when all acidic groups are converted to the corresponding methyl esters. Together, these H/D exchange results indicate that the acidic hydrogens are ''mobile locally'' because they are able to participate in exchange even in the absence of an added proton. Fragmentation of two distinct (H+)P+LDIFSDF ion populations shows the non-exchanging population displays selective cleavage, while the exchanging population fragments more evenly across the peptide backbone. This result demonstrates that H/D exchange can sometimes distinguish between and provide a means of separation of different protonation motifs, and that these protonation motifs can have an effect on the fragmentation.

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

    Science.gov (United States)

    Singal, Ashok K.

    2017-03-01

    From the expression for the electromagnetic field in the neighborhood of a point charge, we determine the rate of electromagnetic momentum flow, calculated using the Maxwell stress tensor, across a surface surrounding the charge. From that we derive for a "point" charge the radiation reaction formula, which turns out to be proportional to the first time-derivative of the acceleration of the charge, identical to the expression for the self-force, hitherto obtained in the literature from the detailed mutual interaction between constituents of a small charged sphere. We then use relativistic transformations to arrive at a generalized formula for radiation reaction for a point charge undergoing relativistic motion.

  11. 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.

  12. 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.

  13. 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...

  14. Charge state distributions and charge exchange cross sections of carbon in helium at 30-258 keV

    Science.gov (United States)

    Maxeiner, Sascha; Seiler, Martin; Suter, Martin; Synal, Hans-Arno

    2015-10-01

    With the introduction of helium stripping in radiocarbon (14C) accelerator mass spectrometry (AMS), higher +1 charge state yields in the 200 keV region and fewer beam losses are observed compared to nitrogen or argon stripping. To investigate the feasibility of even lower beam energies for 14C analyses the stripping characteristics of carbon in helium need to be further studied. Using two different AMS systems at ETH Zurich (myCADAS and MICADAS), ion beam transmissions of carbon ions for the charge states -1, +1, +2 and +3 were measured in the range of 258 keV down to 30 keV. The correction for beam losses and the extraction of charge state yields and charge exchange cross sections will be presented. An increase in population of the +1 charge state towards the lowest measured energies up to 75% was found as well as agreement with previous data from literature. The findings suggest that more compact radiocarbon AMS systems are possible and could provide even higher efficiency than current systems operating in the 200 keV range.

  15. 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.

  16. High spatial and temporal resolution charge exchange recombination spectroscopy on the HL-2A tokamak

    NARCIS (Netherlands)

    Wei, Y. L.; Yu, D. L.; Liu, L.; Ida, K.; von Hellermann, M.; Cao, J. Y.; Sun, A. P.; Ma, Q.; Chen, W. J.; Liu, Yi; Yan, L. W.; Yang, Q. W.; Duan, X. R.; Liu, Yong

    2014-01-01

    A 32/64-channel charge exchange recombination spectroscopy (CXRS) diagnostic system is developed on the HL-2A tokamak (R = 1.65 m, a = 0.4 m), monitoring plasma ion temperature and toroidal rotation velocity simultaneously. A high throughput spectrometer (F/2.8) and a pitch-controlled fiber bundle e

  17. Conceptual design of the ITER upper port plug for charge exchange diagnostic

    NARCIS (Netherlands)

    Sadakov, S.; Baross, T.; Biel, W.; Borsuk, V.; Hawkes, N.; Hellermann, M. von; Gille, P.; Kiss, G.; Koning, J.; Knaup, M.; Klinkhamer, J.F.F.; Krasikov, Yu.; Litnovsky, A.; Neubauer, O.; Panin, A.

    2009-01-01

    A plug for the ITER core charge exchange recombination spectroscopy (core CXRS) is located in the upper port 3. It transfers the light emitted by interaction of plasma ions with the diagnostic neutral beam (DNB). The plug consists of a main shell, a shielding cassette and a retractable tube. The tub

  18. Microscopic structure of charge-exchange spin-isospin modes through decay measurements

    NARCIS (Netherlands)

    Harakeh, M.N.

    1998-01-01

    The study of particle decay of charge-exchange giant resonances (CEGR) furnishes information on their microscopic structure. Furthermore, gamma decay of CEGR call help to unravel their structure. For example, the gamma-decay of the Gamow-Teller (GT) resonance to the isobaric analogue state (IAS) poi

  19. Thermochemistry and Charge Delocalization in Cyclization Reactions Using Accurate Quantum Monte Carlo Calculations

    Science.gov (United States)

    Saritas, Kayahan; Grossman, Jeffrey C.

    2015-03-01

    Molecules that undergo pericyclic isomerization reactions find interesting optical and energy storage applications, because of their usually high quantum yields, large spectral shifts and small structural changes upon light absorption. These reactions induce a drastic change in the conjugated structure such that substituents that become a part of the conjugated system upon isomerization can play an important role in determining properties such as enthalpy of isomerization and HOMO-LUMO gap. Therefore, theoretical investigations dealing with such systems should be capable of accurately capturing the interplay between electron correlation and exchange effects. In this work, we examine the dihydroazulene isomerization as an example conjugated system. We employ the highly accurate quantum Monte Carlo (QMC) method to predict thermochemical properties and to benchmark results from density functional theory (DFT) methods. Although DFT provides sufficient accuracy for similar systems, in this particular system, DFT predictions of ground state and reaction paths are inconsistent and non-systematic errors arise. We present a comparison between QMC and DFT results for enthalpy of isomerization, HOMO-LUMO gap and charge densities with a range of DFT functionals.

  20. Charge exchange collisions of slow C6 + with atomic and molecular H

    Science.gov (United States)

    Saha, Bidhan C.; Guevara, Nicolais L.; Sabin, John R.; Deumens, Erik; Öhrn, Yngve

    2016-04-01

    Charge exchange in collisions of C6+ ions with H and H2 is investigated theoretically at projectile energies 0.1 motions. Both the total and partial cross sections are reported for the collision of C6+ ions with atomic and molecular hydrogen. A comparison with other theoretical and experimental results shows, in general good agreement except at very low energy, considered here. For H2, the one- and two-electron charge exchange cross sections are calculated and compared with other theoretical and experimental results. Small but non-negligible isotope effects are found at the lowest energy studied in the charge transfer of C6+ with H. In low energy region, it is observed that H2 has larger isotope effects than H atom due to the polarizability effect which is larger than the mass effect.

  1. Measurement of the $\\bar{p}p \\rightarrow \\bar{n}n$ Charge-Exchange Differential Cross-Section

    CERN Multimedia

    2002-01-01

    The aim of this proposal is a measurement of the differential cross-section of the $\\bar{p}$p $\\rightarrow$ $\\bar{n}$n charge-exchange reaction with a point-to-point precision of 1\\% in the forward direction, and an absolute normalization error of 3\\%. The high precision of the data should allow, inter alia, a determination of the $\\pi$NN coupling constant to better than 2\\%.\\\\ \\\\ The measurement will be done using the existing neutron and antineutron detectors built for experiment PS199 and liquid hydrogen target. In one week of running time, with a $\\bar{p}$ beam intensity of 3 $ 10 ^{5} $ $\\bar{p}$/sec, the reaction will be measured at a few $\\bar{p}$ momenta, in the range 500 to 900~MeV/c.

  2. 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.

  3. Transport, charge exchange and loss of energetic heavy ions in the earth's radiation belts - Applicability and limitations of theory

    Science.gov (United States)

    Spjeldvik, W. N.

    1981-01-01

    Computer simulations of processes which control the relative abundances of ions in the trapping regions of geospace are compared with observations from discriminating ion detectors. Energy losses due to Coulomb collisions between ions and exospheric neutrals are considered, along with charge exchange losses and internal charge exchanges. The time evolution of energetic ion fluxes of equatorially mirroring ions under radial diffusion is modelled to include geomagnetic and geoelectric fluctutations. Limits to the validity of diffusion transport theory are discussed, and the simulation is noted to contain provisions for six ionic charge states and the source effect on the radiation belt oxygen ion distributions. Comparisons are made with ion flux data gathered on Explorer 45 and ISEE-1 spacecraft and results indicate that internal charge exchanges cause the radiation belt ion charge state to be independent of source charge rate characteristics, and relative charge state distribution is independent of the radially diffusive transport rate below the charge state redistribution zone.

  4. Charge symmetry breaking in the reaction np -> d pi sup 0

    CERN Document Server

    Opper, A K; Churchman, R M; Davis, C A; Finlay, R W; Green, P W; Greeniaus, L G; Hutcheon, D A; Jordan, D V; Korkmaz, E J; Niskanen, J A; O'Rielly, G V; Porcelli, T; Reitzner, S D; Walden, P L; Yen, S

    2000-01-01

    Charge Symmetry Breaking (CSB) in the strong interaction is due ultimately to the mass difference between the u and d quarks, but is described conveniently by meson-exchange models. TRIUMF experiment E704 measures the forward-backward asymmetry (A sub f sub b) in np->d pi sup 0 , which must be zero in the centre-of-mass if charge symmetry is conserved. The angle-integrated value of A sub f sub b is calculated to be -35x10 sup - sup 4 near 280 MeV with the dominant contribution coming from (pi sup 0 -eta) and (pi sup 0 -eta') mixing. The experiment uses a neutron beam of 279.5 MeV, a liquid hydrogen target, and the SASP spectrometer to detect deuterons from the np->d pi sup 0 reaction. A measurement of the pp->d pi sup + distribution, for which A sub f sub b must be zero, provides a strong test of systematic errors.

  5. Signatures of the electron saddle swaps mechanism in the photon spectra following charge-exchange collisions

    Science.gov (United States)

    Otranto, Sebastian

    2014-10-01

    During the last few years, several experimental and theoretical studies have focused on state selective charge exchange processes between charged ions and alkali metals. These data are of particular importance for the tokamak nuclear fusion reactor program, since diagnostics on the plasma usually rely on charge-exchange spectroscopy. In this sense, alkali metals, have been proposed as potential alternatives to excited hydrogen/deuterium for which laboratory experiments are not feasible at present. In this talk, we present our recent work involving ion collisions with alkali metals. Oscillatory structures in the angular differential charge-exchange cross sections obtained using the MOTRIMS technique are correctly described by classical trajectory Monte Carlo simulations. These oscillations are found to originate from the number of swaps the electron undergoes around the projectile-target potential saddle before capture takes place and are very prominent at impact energies below 10 keV/amu. Moreover, cross sections of higher order of differentiability also indicate that the swaps leave distinctive signatures in the (n,l)-state selective cross sections and in the photon line emission cross sections. Oscillatory structures for the x-ray hardness ratio parameter are also predicted. In collaboration with Ronnie Hoekstra, Zernike Institute for Advanced Materials, University of Groningen and Ronald Olson, Department of Physics, Missouri University of Science and Technology.

  6. Absolute Charge Exchange Cross Sections for ^3He^2+ Collisions with ^4He and H_2

    Science.gov (United States)

    Mawhorter, R. J.; Greenwood, J.; Smith, S. J.; Chutjian, A.

    2002-05-01

    The JPL charge exchange beam-line(J.B. Greenwood, et al., Phys. Rev A 63), 062707 (2001) was modified to increase the forward acceptance angle and enable the measurement of total charge-exchange cross sections for slow, light, highly-charged ion collisions with neutral targets(R. E. Olson and M. Kimura, J. Phys. B 15), 4231 (1982). Data are presented for single charge exchange cross sections for ^3He^2+ nuclei scattered by ^4He and H2 in the energy range 0.33-4.67 keV/amu. For both targets there is good agreement with Kusakabe, et al.(T. Kusakabe, et al., J. Phys. Soc. Japan 59), 1218 (1990). Angular collection is studied by a comparison with differential measurements(D. Bordenave-Montesquieu and R. Dagnac, J. Phys. B 27), 543 (1994), as well as with earlier JPL results(J.B. Greenwood, et al., Ap. J. 533), L175 (2000), ibid. 529, 605 (2000) using heavier projectiles and targets. This work was carried out at JPL/Caltech, and was supported through contract with NASA. RJM thanks the NRC for a Senior Associateship at JPL.

  7. Oxygen Atom Exchange Mechanism in Reaction of OH Radical with AsO

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Oxygen atom exchange reaction mechanism in the reaction of OH radicals with AsO was investigated by means of the density functional theory (DFT) with 6-311++G(3df,3pd) and 6-311++G(d,p) basis sets. The calculated results suggest that the reaction between OH and AsO should make the oxygen atoms exchange rapidly because the barrier to isomerization is significantly less than the HO-AsO bond dissociation energy.

  8. Fast charge exchange ions in high power impulse magnetron sputtering of titanium as probes for the electrical potential

    Science.gov (United States)

    Breilmann, W.; Maszl, C.; von Keudell, A.

    2017-03-01

    High power impulse magnetron sputtering (HiPIMS) plasmas exhibit a high ionization fraction of the sputtered material and ions with high kinetic energies, which produce thin films with superior quality. These ion energy distribution functions (IEDF) contain energetic peaks, which are believed to be linked to a distinct electrical potential hump {{Δ }}{{{Φ }}}{{ionization}{{zone}}} inside rotating localized ionization zones, so called spokes, at target power densities above 1 kW cm‑2. Any direct measurement of this electrical potential structure is, however, very difficult due to the dynamic nature of the spokes and the very high local power density, which hampers the use of conventional emissive probes. Instead, we use a careful analysis of the IEDFs for singly and doubly charged titanium ions from a HiPIMS plasma at varying target power density. The energy peaks in the IEDFs measured at the substrate depend on the point of ionization and any charge exchange collisions on the path between ionization and impact at the substrate. Thereby, the IEDFs contain a convoluted information about the electrical potential structure inside the plasma. The analysis of these IEDFs reveal that higher ionization states originate at high target power densities from the central part of the plasma spoke, whereas singly charged ions originate from the perimeter of the plasma spoke. Consequently, we observe different absolute ion energies with the energy of Ti2+ being slightly higher than two times the energy of Ti+. Additional peaks are observed in the IEDFs of Ti+ originating from charge exchange reactions from Ti2+ and Ti3+ with titanium neutrals. Based on this analysis of the IEDFs, the structure of the electrical potential inside a spoke is inferred yielding {{Δ }}{{{Φ }}}{{ionization}{{zone}}} = 25 V above the plasma potential, irrespective of target power density.

  9. Entropy Exchange in Coupled Field-Superconducting Charge Qubit System with Intrinsic Decoherence

    Institute of Scientific and Technical Information of China (English)

    SHAO Bin; ZHANG Jian; ZOU Jian

    2006-01-01

    Based on the intrinsic decoherence effect, partial entropy properties of a super conducting charge qubitinside a single-mode cavity field is investigated, and entropy exchange which is recently regarded as a kind of anti-correlated behavior of the entropy between subsystems is explored. Our results show that although the intrinsic decoherenceleads to an effective irreversible evolution of the interacting system due to a suppression of coherent quantum features through the decay of off-diagonal matrix elements of the density operator and has an apparently influence on the partial entropy of two individual subsystems, it does not effect the entropy exchange between the two subsystems.

  10. 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...

  11. Pionic charge exchange on the proton from 40 to 250 MeV

    Science.gov (United States)

    Breitschopf, J.; Bauer, M.; Clement, H.; Cröni, M.; Denz, H.; Friedman, E.; Gibson, E. F.; Meier, R.; Wagner, G. J.

    2006-08-01

    The total cross sections for pionic charge exchange on hydrogen were measured using a transmission technique on thin CH2 and C targets. Data were taken for π- lab energies from 39 to 247 MeV with total errors of typically 2% over the Δ-resonance and up to 10% at the lowest energies. Deviations from the predictions of the SAID phase shift analysis in the 60-80 MeV region are interpreted as evidence for isospin-symmetry breaking in the s-wave amplitudes. The charge dependence of the Δ-resonance properties appears to be smaller than previously reported.

  12. 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.

  13. Polarization of the Charge-Exchange X-rays Induced in the Heliosphere

    CERN Document Server

    Gacesa, Marko; Côt\\/e, Robin; Kharchenko, Vasili

    2011-01-01

    We report results of a theoretical investigation of polarization of the X-ray emissions induced in charge-exchange collisions of fully stripped solar wind ions C$^{6+}$ and O$^{8+}$ with the heliospheric hydrogen atoms. The polarization of X-ray emissions has been computed for line-of-sight observations within the ecliptic plane as a function of solar wind ion velocities, including a range of velocities corresponding to the slow and fast solar wind, and Coronal Mass Ejections. To determine the variability of polarization of heliospheric X-ray emissions, the polarization has been computed for solar minimum conditions with self-consistent parameters of the solar wind plasma and heliospheric gas and compared with the polarization calculated for an averaged solar activity. We predict the polarization of charge-exchange X-rays to be between 3% and 8%, depending on the line-of-sight geometry, solar wind ion velocity, and the selected emission lines.

  14. 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.

  15. 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.

  16. 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.

  17. Using Kappa Functions to Characterize Outer Heliosphere Proton Distributions in the Presence of Charge-exchange

    Science.gov (United States)

    Zirnstein, E. J.; McComas, D. J.

    2015-12-01

    Kappa functions have long been used in the analysis and modeling of suprathermal particles in various space plasmas. In situ observations of the supersonic solar wind show its distribution contains a cold ion core and power-law tail, which is well-represented by a kappa function. In situ plasma observations by Voyager, as well as observations of energetic neutral atom (ENA) spectra by the Interstellar Boundary Explorer (IBEX), showed that the compressed and heated inner heliosheath (IHS) plasma beyond the termination shock can also be represented by a kappa function. IBEX exposes the IHS plasma properties through the detection of ENAs generated by charge-exchange in the IHS. However, charge-exchange modifies the plasma as it flows through the IHS, and makes it difficult to ascertain the parent proton distribution. In this paper we investigate the evolution of proton distributions, initially represented by a kappa function, that experience losses due to charge-exchange in the IHS. In the absence of other processes, it is no longer representable by a single kappa function due to the energy-dependent, charge-exchange process. While one can still fit a kappa function to the evolving proton distribution over limited energy ranges, this yields fitting parameters (pseudo-density, pseudo-temperature, pseudo-kappa index) that depend on the energy range of the fit. We discuss the effects of fitting a kappa function to the IHS proton distribution over limited energy ranges, its dependence on the initial proton distribution properties at the termination shock, and implications for understanding the observations.

  18. The inconsistency between proton charge exchange and the observed ring current decay

    Science.gov (United States)

    Lyons, L. R.; Evans, D. S.

    1976-01-01

    The equatorial pitch-angle distributions of ring-current ions observed during a storm recovery phase at L values between 3 and 4 are compared with the pitch-angle distributions predicted by proton charge exchange with neutral hydrogen. Large disagreements are found, and three alternative explanations are explored. (1) A strong proton source acts to mask the effects of charge exchange. It is believed that the required strong continual source with a unique pitch-angle and energy dependence is unrealistic at these low L values. (2) Presently accepted neutral hydrogen density models have densities well over an order of magnitude too large for a storm recovery phase. No evidence is known to support the required large errors in the densities. (3) The ring current at particle energies not exceeding 50 keV was dominated by some ion species other than protons during the storm recovery phase. Such ions must have much longer lifetimes for charge exchange with hydrogen than do protons. This alternative is strongly favored, with He(+) being an attractive candidate.

  19. 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