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Sample records for coherent pion emission

  1. Quantum mechanical signature in exclusive coherent pion production

    Science.gov (United States)

    Deutchman, P. A.; Buvel, R. L.; Maung, K. M.; Norbury, J. W.; Townsend, L. W.

    1986-01-01

    We calculate the coherent production of pions from subthreshold to relativistic energies in heavy-ion collisions using a quantum, microscopic, many-body model. For the first time, in this approach, we use harmonic oscillator wave functions to describe shell-model information. The theoretical quantum mechanical results obtained for the pion spectra represent an important improvement over our previous microscopic, many-body calculations.

  2. Coherent pion production induced by protons and light ions

    International Nuclear Information System (INIS)

    Fernandez de Cordoba, P.; Oset, E.; Vicente-Vacas, M.J.

    1995-01-01

    We study coherent pion production by means of the (p,n) and (He,t) reactions on different nuclei and at different energies of the projectile. Energy and angular distributions are calculated. The angular distributions are rather narrow along the direction of the momentum transfer, particularly in heavy nuclei. The reaction is sensitive to the longitudinal part of the elementary NN→NΔ interaction. It also provides a new tool to obtain information on the pion-nuclear interaction, complementary to that offered by reactions with real pions. (orig.)

  3. Coherent pion photoproduction from deuterium at intermediate energies

    International Nuclear Information System (INIS)

    Osland, P.; Rej, A.K.

    1975-12-01

    The coherent photoproduction of neutral pions on deuterons is studied at energies around the (3,3) resonance and discuss the effects of the Fermi motion, rescattering and kinematical approximations. The results are very dependent upon what kinematical approximations one adopts for the impulse approximation term, which dominates up to very large angles. Allowing for this uncertainty in the kinematics, our results are in good agreement with the most recent experimental data

  4. Theoretical contributions to coherent pion production in subthreshold and relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Deutchman, P.A.; Norbury, J.W.; Townsend, L.W.

    1986-01-01

    The analysis results from a microscopic calculation for pion production in heavy-ion collisions at intermediate to relativistic energies both above and below pion threshold are presented and the most important terms that contribute to the pion spectrum are determined. The energy dependence and the effects on the pion spectrum due to the various parameters in the theory are examined. The model is applied to coherent pion-production in 16 O + 12 C collisions. (orig.)

  5. Coherent and chaotic generation of pions from relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Nakamura, Hiroki; Seki, Ryoichi

    2002-01-01

    Based on the recent NA44 and WA98 two- and three-pion interferometry data together with the WA98 pion multiplicity information, we observe that the pions may be mostly emitted from chaotic sources in the peripheral events and coherent pions are mostly generated in the central events. A more refined analysis would be needed, however, to make our observation conclusive by quantifying various effects such as resonance formation of the emerging pions and also experimental uncertainties

  6. Multipion correlations induced by isospin conservation of coherent emission

    International Nuclear Information System (INIS)

    Gangadharan, Dhevan

    2016-01-01

    Recent measurements have revealed a significant suppression of multipion Bose–Einstein correlations in heavy-ion collisions at the LHC. The suppression may be explained by postulating coherent pion emission. Typically, the suppression of Bose–Einstein correlations due to coherence is taken into account with the coherent state formalism in quantum optics. However, since charged pion correlations are most often measured, the additional constraint of isospin conservation, which is absent in quantum optics, needs to be taken into account. As a consequence, correlations emerge between pions of opposite charge. A calculation of the correlations induced by isospin conservation of coherent emission is made for two, three- and four-pion correlation functions and compared to the data from the LHC.

  7. Measurement of Charged Current Coherent Pion Production by Neutrinos on Carbon at MINER$\

    Energy Technology Data Exchange (ETDEWEB)

    Mislivec, Aaron Robert [Univ. of Rochester, NY (United States)

    2017-01-01

    Neutrino-nucleus coherent pion production is a rare neutrino scattering process where the squared four-momentum transferred to the nucleus is small, a lepton and pion are produced in the forward direction, and the nucleus remains in its initial state. This process is an important background in neutrino oscillation experiments. Measurements of coherent pion production are needed to constrain models which are used to predict coherent pion production in oscillation experiments. This thesis reports measurements of νµ and νµ charged current coherent pion production on carbon for neutrino energies in the range 2 < Eν < 20 GeV. The measurements were made using data from MINERνA, which is a dedicated neutrino-nucleus scattering experiment that uses a fi scintillator tracking detector in the high-intensity NuMI neutrino beam at Fermilab. Coherent interactions were isolated from the data using only model-independent signatures of the reaction, which are a forward muon and pion, no evidence of nuclear breakup, and small four-momentum transfer to the nucleus. The measurements were compared to the coherent pion production model used by oscillation experiments. The data and model agree in the total interaction rate and are similar in the dependence of the interaction rate on the squared four- momentum transferred from the neutrino. The data and model disagree significantly in the pion kinematics. The measured νµ and νµ interaction rates are consistent, which supports model predictions that the neutrino and antineutrino interaction rates are equal.

  8. Coherent pions as the origin of excessive soft photons in hadron collisions

    International Nuclear Information System (INIS)

    Lo, S.Y.; Schreiber, A.

    1986-01-01

    The published inclusive photon spectrum from 70 GeV/c K + p interactions can be fitted by using a simple model of semi-coherent π 0 -production. The model relies on the fact that the size of the production region is of the order of fermis and hence the uncertainty relation plays a dominant role in the production of coherent pions. (orig.)

  9. Neutrino emission in inhomogeneous pion condensed quark matter

    International Nuclear Information System (INIS)

    Huang, Xuguang; Wang, Qun; Zhuang, Pengfei

    2008-01-01

    It is believed that quark matter can exist in neutron star interior if the baryon density is high enough. When there is a large isospin density, quark matter could be in a pion condensed phase. We compute neutrino emission from direct Urca processes in such a phase, particularly in the inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states. The neutrino emissivity and specific heat are obtained, from which the cooling rate is estimated. (author)

  10. Total and differential cross sections for pion production via coherent isobar and giant resonance formation in heavy-ion collisions

    International Nuclear Information System (INIS)

    Deutchman, P.A.; Norbury, J.W.; Townsend, L.W.

    1985-01-01

    A quantal many-body formalism is presented that investigates pion production through the coherent formation of a nucleonic isobar in the projectile and its subsequent decay to various pion charge states along with concomitant excitation of the target to a coherent spin-isospin giant resonance via a peripheral collision of relativistic heavy ions. Total cross sections as a function of the incident energy per nucleon and Lorentz-invariant differential cross sections as a function of pion energy and angle are calculated. It is shown that the pion angular distributions, in coincidence with the target giant resonance excitations, might provide a well-defined signature for these coherent processes

  11. Neutrino-nucleus cross-sections: a unified theoretical approach for nucleon knock-out, coherent and incoherent pion production

    CERN Document Server

    Martini, M; G. Chanfray; Marteau, J

    2010-01-01

    Neutrino-nucleus cross-sections are needed to interpret neutrino oscillation data, as neutrino detectors involve complex nuclei. We present a theory of neutrino interactions with nuclei aimed at a unified description of the partial cross-sections, namely quasi-elastic and multi-nucleon emission, coherent and incoherent single pion production. We compare our approach to the available neutrino experimental data on carbon. We also discuss the evolution of the neutrino cross-sections with the mass number in view of future precision ex- periments which will use a liquid argon chamber.

  12. Can we see scalar, pseudoscalar or tensor interactions in coherent pion production?

    International Nuclear Information System (INIS)

    Rein, D.

    1988-01-01

    The possibility to detect nonconventional scalar, pseudoscalar or tensor interactions (SPT) in the angular distribution of pions produced coherently in neutrino nucleus reactions is reexamined. It is found that the angular distribution does not differ qualitatively from a corresponding distribution arising from conventional vector-axial vector (VA) interactions unless the energy of the outgoing pion is restricted. Even then SPT interactions are likely to be overshadowed by transverse VA interactions which can mimic the former at finite although small momentum transfer Q 2 . (author)

  13. Anisotropy of the pion emission in relativistic nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Babinet, R.; Cavata, C.; Demoulins, M.; Fanet, H.; Gosset, J.; Lemaire, M.C.; Le Merdy, A.; L'Hote, D.; Lucas, B.; Poitou, J.; Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Dupieux, P.; Fraysse, L.; Marroncle, J.; Montarou, G.; Parizet, M.J.; Ramani, A.; Brochard, F.; Gorodetzky, P.; Racca, C.

    1990-01-01

    The production of pions and baryons from Ne and Ar induced reactions on Ca, NaF, Nb and Pb targets, in the range of .2 to 1 GeV per nucleon, is discussed. The 4π detector Diogenes at the Saturne accelerator facility is applied. The reaction plane is determined from the baryon momenta distribution and used as a reference for the pion triple differential cross-sections. A transverse momentum analysis is carried out for baryons and pions. The pion squared reduced impact parameter and the flow characteristics are given. The results show that the azimuthal anisotropy of pion emission increases with the asymmetry of the system. The evidence that pion absorption effects may be responsible for the azimuthal anisotropy of the pion emission is provided

  14. Pion production - a probe for coherence in medium energy heavy ion collisions

    International Nuclear Information System (INIS)

    Stachel, J.

    1985-01-01

    Neutral pion production is observed in heavy ion collisions at beam energies as low as 25 MeV/u, where this process is consumming the major portion of the total center of mass energy available. At these low beam energies single nucleon nucleon collision models and also models that incorporate the cooperative sharing of the beam energy of several nucleons do not reproduce the data. Rather, the data presented here call for a fully coherent production mechanism. (orig.)

  15. Coherent pion production in 12C(p,nπ) at 800MeV

    International Nuclear Information System (INIS)

    Gilman, R.; Brash, E.; Edwards, G.; Glashausser, C.; Jones, M.K.; Baker, F.T.; Bastea, S.; Beatty, D.P.; Bimbot, L.; Brusoe, J.; Chiba, J.; Cooper, D.; Kumbartzki, G.; Mauger, C.; Nagae, T.; Park, B.; Prout, D.; Ransome, R.D.; Rawool-Sullivan, M.; Rutt, P.; Storm, B.; Sugarbaker, E.; Taddeucci, T.; Zumbro, J.

    1994-01-01

    Studies of the production of the Δ resonance in hadronic charge exchange reactions show a shift in the Δ peak position. Measurements looking also at the Δ decay products give some evidence for coherent pion production. We have recently completed a new measurement of the 12 C(p,n) reaction leading to the Δ resonance, including a higher resolution coincidence measurement of decay π's in the forward direction. We describe the experiment and some aspects of the preliminary analysis. ((orig.))

  16. Recent experimental results on Coherent Pion production in neutrino interactions

    Energy Technology Data Exchange (ETDEWEB)

    Camilleri, L. [Columbia University, Nevis Labs Irvington on Hudson, New York 10533 (United States)

    2012-08-15

    Recent experimental results on charged current ({pi}{sup +}) coherent production by KEK and SciBooNE and neutral current ({pi}{sup 0}) production by MiniBooNE, SciBooNE and NOMAD will be discussed. The NOMAD results are at an average neutrino energy of 25 GeV whereas the energies of the other experiments are in an average energy range of 1-2 GeV. A comparison with some theoretical models will be presented.

  17. A Unified approach for nucleon knock-out, coherent and incoherent pion production in neutrino interactions with nuclei

    CERN Document Server

    Martini, M.; Chanfray, G.; Marteau, J.

    2009-01-01

    We present a theory of neutrino interactions with nuclei aimed at the description of the partial cross-sections, namely quasi-elastic and multi-nucleon emission, coherent and incoherent single pion production. For this purpose, we use the theory of nuclear responses treated in the random phase approximation, which allows a unified description of these channels. It is particularly suited for the coherent pion production where collective effects are important whereas they are moderate in the other channels. We also study the evolution of the neutrino cross-sections with the mass number from carbon to calcium. We compare our approach to the available neutrino experimental data on carbon. We put a particular emphasis on the multi-nucleon channel, which at present is not easily distinguishable from the quasi-elastic events. This component turns out to be quite relevant for the interpretation of experiments (K2K, MiniBooNE, SciBooNE). It can account in particular for the unexpected behavior of the quasi-elastic cro...

  18. Mechanism for coherent production of pions from the decay of resonances

    International Nuclear Information System (INIS)

    Lam, C.S.; Lo, S.Y.

    1984-01-01

    Conditions and signatures for the induced emission of bosons from a microscopic device are discussed. Detailed formulae for a simple two-level model are derived. In this model the decay of N Δ-resonances residing in a microscopic volume V is discussed. It is shown that large amplification factors for unusual charge bunching of pions are obtained as a result of induced emissions

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

    Energy Technology Data Exchange (ETDEWEB)

    Farhi, L.; Roy-Stephan, M.; Boyard, J.L. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Hennino, T.; Kagarlis, M.; Radvanyi, P. [Laboratoire National Saturne - Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France); Dahl, R.; Ellegaard, C. [Niels Bohr Inst., Copenhagen (Denmark); Augustiniak, W.; Zupranski, P. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)] [and others

    1996-12-31

    The ({sup 3}He,t) charge exchange reaction at 2. GeV incident energy with the new setup SPES IV-{pi} has been realized in order to study the coherent production process of pions. This setup allows to isolate the ground state of the target nucleus, and to sign this process without ambiguity. Some preliminary results in target excitation energy and transferred energy are given. (author). 8 refs.

  20. Coherent production of two and three pions in pd reactions at 19 GeV/c

    International Nuclear Information System (INIS)

    Bakken, V.; Gennow, H.; Lundborg, P.; Maekelae, J.; Moellerud, R.; Pimiae, M.; Sellden, B.; Sundell, E.; Tuominemi, J.K.

    1976-10-01

    The coherent reactions pd→pdπ + π - , pd→pdπ + π - π 0 and pd→ndπ + π + π - are studied. In the two first reactions strong production of Δ ++ (1236) is observed. Production of d* 0 and d* + is observed in the first and second reactions respectively. The forward slope of the t-distribution of the pπ + π - system in the pd→pdπ + π - channel decreases with increasing mass. The 1500 and 1700 MeV enhancements in the pπ + π - mass spectrum of this channel are studied. Assuming that the Gribov-Morrison rule holds, it is found that by analysing the moments of the decay angular distributions that the resonances N(1470), N(1520) and N(1688) are the most likely resonances to be identified with these enhancements. Evidence is found against s-channel helicity conservation and some evidence against t-channel helicity conservation. The decay parameters of the Δ ++ (1236) in the reaction pd→Δ ++ π - d are in good agreement with the predictions of a one-pion exchange model. (Auth.)

  1. Impact parameter analysis of coherent and incoherent pion production on nuclei by 11.7GeV/c π+

    International Nuclear Information System (INIS)

    Arnold, R.; Barshay, S.; Riester, J.L.

    1976-01-01

    Using the complete momentum measurements for 2, 3, 4 and 5 pion final states. The impact parameter structure, with the following principal results has been studied. Evidence is presented for an empirical method that can help in the separation of coherent events on nuclei. Incoherent nuclear production exhibits lower-bound impact parameters which decrease systematically with an increasing number of produced pions. The experimental b-distributions can be very well fitted by a single simple scaled functional form, dsigmasub(N)(b)/d 2 bvector proportional to F(N/f(b)), this N-distribution yields a ratio (dispersion/average dispersion) of about 0.35 at any impact parameter [fr

  2. Charged pion coherent production in nucleus-nucleus collisions at incident energies between 86 and 330 MeV/nucleon

    International Nuclear Information System (INIS)

    Fassnacht, P.

    1984-01-01

    We have studied pion production in nucleus-nucleus collisions at foward angles for about twenty projectile target combinations. The incident energies were below or around 300 MeV/nucleon which is the threshold of the elementary reaction NN → NNπ. The study of the inclusive spectra shows some new ideas: shell effects in pion production, collective resonances excitations. These spectra have been analyzed following different models: hard-scattering models which describe the interaction on the basis of the elementary reaction NN → NNπ, statistical model and the pionic cloud model which is a coherent description of the interaction. In the study of the exclusive reactions, we established some empiric rules concerning the cross-section variations. These exclusive spectra were then analyzed in the framework of two-models: the semi-phenomenological model and the pionic fusion [fr

  3. Coherence energies in pre-equilibrium emission

    International Nuclear Information System (INIS)

    De Rosa, A.; Inglima, C.; Perillo, E.; Rosato, E.; Sandoli, M.; Spadaccini, G.

    1979-01-01

    A method, based on the spectral density analysis, has been developped in order to evaluate coherence of statistical fluctuations. It is specially suitable for reactions showing the contemporary presence of different emission mechanism (e.g. preequilibrium and evaporation - like mechanism)

  4. Coherent emission mechanisms in astrophysical plasmas

    Science.gov (United States)

    Melrose, D. B.

    2017-12-01

    Three known examples of coherent emission in radio astronomical sources are reviewed: plasma emission, electron cyclotron maser emission (ECME) and pulsar radio emission. Plasma emission is a multi-stage mechanism with the first stage being generation of Langmuir waves through a streaming instability, and subsequent stages involving partial conversion of the Langmuir turbulence into escaping radiation at the fundamental (F) and second harmonic (H) of the plasma frequency. The early development and subsequent refinements of the theory, motivated by application to solar radio bursts, are reviewed. The driver of the instability is faster electrons outpacing slower electrons, resulting in a positive gradient ({d}f(v_allel )/{d}v_allel >0) at the front of the beam. Despite many successes of the theory, there is no widely accepted explanation for type I bursts and various radio continua. The earliest models for ECME were purely theoretical, and the theory was later adapted and applied to Jupiter (DAM), the Earth (AKR), solar spike bursts and flare stars. ECME strongly favors the x mode, whereas plasma emission favors the o mode. Two drivers for ECME are a ring feature (implying {d}f(v)/{d}v>0) and a loss-cone feature. Loss-cone-driven ECME was initially favored for all applications. The now favored driver for AKR is the ring-feature in a horseshoe distribution, which results from acceleration by a parallel electric on converging magnetic field lines. The driver in DAM and solar and stellar applications is uncertain. The pulsar radio emission mechanism remains an enigma. Ingredients needed in discussing possible mechanisms are reviewed: general properties of pulsars, pulsar electrodynamics, the properties of pulsar plasma and wave dispersion in such plasma. Four specific emission mechanisms (curvature emission, linear acceleration emission, relativistic plasma emission and anomalous Doppler emission) are discussed and it is argued that all encounter difficulties. Coherent

  5. A Measurement of Coherent Neutral Pion Production in Neutrino Neutral Current Interactions in NOMAD experiment

    CERN Document Server

    Kullenberg, C T

    2009-01-01

    We present a study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to $1.44 \\times 10^6$ muon-neutrino Charged Current interactions in the energy range $2.5 \\leq E_{\

  6. Coherent production of single pions and ρ mesons in charged-current interactions of neutrinos and antineutrinos on neon nuclei at the Fermilab Tevatron

    Science.gov (United States)

    Willocq, S.; Aderholz, M.; Akbari, H.; Allport, P. P.; Badyal, S. K.; Ballagh, H. C.; Barth, M.; Bingham, H. H.; Brucker, E. B.; Burnstein, R. A.; Cence, R. J.; Chatterjee, T. K.; Clayton, E. F.; Corrigan, G.; de Prospo, D.; Devanand; de Wolf, E.; Faulkner, P. J.; Foeth, H.; Fretter, W. B.; Gupta, V. K.; Hanlon, J.; Harigel, G.; Harris, F. A.; Jacques, P.; Jain, V.; Jones, G. T.; Jones, M. D.; Kafka, T.; Kalelkar, M.; Kohli, J. M.; Koller, E. L.; Krawiec, R. J.; Lauko, M.; Lys, J. E.; Marage, P.; Milburn, R. H.; Mittra, I. S.; Mobayyen, M. M.; Moreels, J.; Morrison, D. R.; Myatt, G.; Nailor, P.; Naon, R.; Napier, A.; Passmore, D.; Peters, M. W.; Peterson, V. Z.; Plano, R.; Rao, N. K.; Rubin, H. A.; Sacton, J.; Sambyal, S. S.; Schmitz, N.; Schneps, J.; Singh, J. B.; Singh, S.; Smart, W.; Stamer, P.; Varvell, K. E.; Verluyten, L.; Wachsmuth, H.; Wainstein, S.; Yost, G. P.

    1993-04-01

    The coherent production of π and ρ mesons in νμ(ν¯μ)-neon charged-current interactions has been studied using the Fermilab 15-foot bubble chamber filled with a heavy Ne-H2 mix and exposed to the Teva- tron quadrupole triplet (anti)neutrino beam. The νμ (ν¯μ) beam had an average energy of 80 GeV (70 GeV). From a sample corresponding to approximately 28 000 charged-current interactions, net signals of (53+/-9) μ+/-π-/+ coherent events and (19+/-7) μ+/-π-/+π0 coherent events are extracted. For E>10 GeV, the coherent pion production cross section is determined to be (3.2+/-0.7)×10-38 cm2 per neon nucleus whereas the coherent ρ production cross section is (2.1+/-0.8)×10-38 cm2 per neon nucleus. These cross sections and the kinematical characteristics of the coherent events at ||t||<0.1 GeV2 are found to be in general agreement with the predictions of a model based on the hadron dominance and, in the pion case, on the partially conserved axial-vector current hypothesis. Also discussed is the coherent production of systems consisting of three pions.

  7. Coherent pion production induced by 300 MeV and 600 MeV deuterons

    International Nuclear Information System (INIS)

    Aslanides, E.; Bergdolt, A.M.; Bing, O.; Fassnacht, P.; Hibou, F.

    1982-01-01

    Experimental data on (d,π - ) reactions at 300 and 600 MeV incident energy are presented. Inclusive spectra on 6 Li, 9 Be and 10 B targets near the kinematical limit do not show the usual scaling behaviour. For the two-body reaction 6 Li (d,π - ) 8 B the lowest-energy discrete states of the final nucleus were clearly resolved and the cross sections for pion production leading to those states have been determined. (orig.)

  8. Preequilibrium particle emissions and in-medium effects on the pion production in heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhao-Qing [Chinese Academy of Sciences, Institute of Modern Physics, Lanzhou (China)

    2017-02-15

    Within the framework of the Lanzhou quantum molecular dynamics (LQMD) transport model, pion dynamics in heavy-ion collisions near threshold energies and the emission of preequilibrium particles (nucleons and light complex fragments) have been investigated. A density, momentum and isospin-dependent pion-nucleon potential based on the Δ-hole model is implemented in the transport approach, which slightly leads to the increase of the π{sup -}/π{sup +} ratio, but reduces the total pion yields. It is found that a bump structure of the π{sup -}/π{sup +} ratio in the kinetic energy spectra appears at the pion energy close to the Δ(1232) resonance region. The yield ratios of neutrons to protons from the squeeze-out particles perpendicular to the reaction plane are sensitive to the stiffness of nuclear symmetry energy, in particular at the high-momentum (kinetic energy) tails. (orig.)

  9. Multi-pion production

    International Nuclear Information System (INIS)

    Beavis, D.; Fung, S.Y.; Gorn, W.; Keane, D.; Liu, Y.M.; Poe, R.T.; VanDalen, G.; Vient, M.

    1984-01-01

    Preliminary analysis of pion production in 1.2 GeV/nucleon Kr-RbBr collisions is presented. The negative pion multiplicity is consistent with a convolution of Poisson distributions and a freeze-out density between 1/3 and 1/2 normal nuclear density is extracted. Global negative pion kinematic variables are used to search for possible structure in the multi-pion emission. No evidence for structured emission or conservation constraints is found. Pion interferometry analysis gives a source radius of 5.4 +- 1.2 Fermi and a freeze-out density of .3 +- .2 times normal nuclear density. 10 refs., 5 figs

  10. Two- and three-pion quantum statistics correlations in Pb-Pb collisions at $\\sqrt{s_{NN}}$=2.76 TeV at the CERN Large Hadron Collider

    CERN Document Server

    Abelev, Betty Bezverkhny; Adamova, Dagmar; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agocs, Andras Gabor; Agostinelli, Andrea; Agrawal, Neelima; Ahammed, Zubayer; Ahmad, Nazeer; Ahmad, Arshad; Ahmed, Ijaz; Ahn, Sang Un; Ahn, Sul-Ah; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arbor, Nicolas; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bairathi, Vipul; Bala, Renu; Baldisseri, Alberto; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Batzing, Paul Christoph; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Berger, Martin Emanuel; Bergognon, Anais Annick Erica; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, Fernando; Blau, Dmitry; Blume, Christoph; Bock, Friederike; Boehmer, Felix Valentin; Bogdanov, Alexey; Boggild, Hans; Bogolyubskiy, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian Heinz; Borel, Herve; Borissov, Alexander; Bornschein, Joerg; Bossu, Francesco; Botje, Michiel; Botta, Elena; Boettger, Stefan; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broker, Theo Alexander; Browning, Tyler Allen; Broz, Michal; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Carena, Francesco; Carena, Wisla; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Casula, Ester Anna Rita; Catanescu, Vasile Ioan; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Cherney, Michael Gerard; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Connors, Megan Elizabeth; Contin, Giacomo; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortese, Pietro; Cortes Maldonado, Ismael; Cosentino, Mauro Rogerio; Costa, Filippo; Crochet, Philippe; Cruz Albino, Rigoberto; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dainese, Andrea; Dang, Ruina; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Kushal; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; Delagrange, Hugues; Deloff, Andrzej; Denes, Ervin Sandor; D'Erasmo, Ginevra; Oliveira Valeriano De Barros, Gabriel; De Caro, Annalisa; De Cataldo, Giacinto; De Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; De Rooij, Raoul Stefan; Diaz Corchero, Miguel Angel; Dietel, Thomas; Divia, Roberto; Di Bari, Domenico; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Domenicis Gimenez, Diogenes; Doenigus, Benjamin; Dordic, Olja; Dorheim, Sverre; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Dutt Mazumder, Abhee Kanti; Elia, Domenico; Engel, Heiko; Erazmus, Barbara Ewa; Erdal, Hege Austrheim; Eschweiler, Dominic; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Evdokimov, Sergey; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Feliciello, Alessandro; Feofilov, Grigory; Ferencei, Jozef; Fernandez Tellez, Arturo; Gonzalez Ferreiro, Elena; Ferretti, Alessandro; Festanti, Andrea; Figiel, Jan; Araujo Silva Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floratos, Emmanouil; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoeje, Jens Joergen; Gagliardi, Martino; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos Cuadrado, Jose; Garcia-Solis, Edmundo Javier; Gargiulo, Corrado; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Ghosh, Sanjay Kumar; Gianotti, Paola; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez Jimenez, Ramon; Gonzalez Zamora, Pedro; Gorbunov, Sergey; Gorlich, Lidia Maria; Gotovac, Sven; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoryev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grynyov, Borys; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gulkanyan, Hrant; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Khan, Kamal; Haake, Rudiger; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harris, John William; Hartmann, Helvi; Harton, Austin Vincent; Hatzifotiadou, Despina; Hayashi, Shinichi; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hicks, Bernard Richard; Hippolyte, Boris; Hladky, Jan; Hristov, Peter Zahariev; Huang, Meidana; Humanic, Thomas; Hutter, Dirk; Hwang, Dae Sung; Ianigro, Jean-Christophe; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Ionita, Costin; Ippolitov, Mikhail; Irfan, Muhammad; Ivanov, Marian; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacholkowski, Adam Wlodzimierz; Jahnke, Cristiane; Jang, Haeng Jin; Janik, Malgorzata Anna; Pahula Hewage, Sandun; Jena, Satyajit; Jimenez Bustamante, Raul Tonatiuh; Jones, Peter Graham; Jung, Hyungtaik; Jusko, Anton; Kalcher, Sebastian; Kalinak, Peter; Kalweit, Alexander Philipp; Kamin, Jason Adrian; Kang, Ju Hwan; Kaplin, Vladimir; Kar, Somnath; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kebschull, Udo Wolfgang; Keidel, Ralf; Ketzer, Bernhard Franz; Khan, Mohammed Mohisin; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Do Won; Kim, Dong Jo; Kim, Jinsook; Kim, Mimae; Kim, Minwoo; Kim, Se Yong; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Kiss, Gabor; Klay, Jennifer Lynn; Klein, Jochen; Klein-Boesing, Christian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Kobdaj, Chinorat; Kohler, Markus Konrad; Kollegger, Thorsten; Kolozhvari, Anatoly; Kondratev, Valerii; Kondratyeva, Natalia; Konevskikh, Artem; Kovalenko, Vladimir; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kravcakova, Adela; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucera, Vit; Kucheryaev, Yury; Kugathasan, Thanushan; Kuhn, Christian Claude; Kuijer, Paulus Gerardus; Kulakov, Igor; Kumar, Jitendra; Kurashvili, Podist; Kurepin, Alexander; Kurepin, Alexey; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasilij; Kweon, Min Jung; Kwon, Youngil; Ladron De Guevara, Pedro; Lagana Fernandes, Caio; Lakomov, Igor; Langoy, Rune; Lara Martinez, Camilo Ernesto; Lardeux, Antoine Xavier; Lattuca, Alessandra; La Pointe, Sarah Louise; La Rocca, Paola; Lea, Ramona; Lee, Graham Richard; Legrand, Iosif; Lehnert, Joerg Walter; Lemmon, Roy Crawford; Lenhardt, Matthieu Laurent; Lenti, Vito; Leogrande, Emilia; Leoncino, Marco; Leon Monzon, Ildefonso; Levai, Peter; Li, Shuang; Lien, Jorgen Andre; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Ljunggren, Hans Martin; Lodato, Davide Francesco; Lonne, Per-Ivar; Loggins, Vera Renee; Loginov, Vitaly; Lohner, Daniel; Loizides, Constantinos; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lu, Xianguo; Luettig, Philipp Johannes; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luzzi, Cinzia; Gago Medina, Alberto Martin; Jacobs, Peter Martin; Ma, Rongrong; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Liudmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Markert, Christina; Marquard, Marco; Martashvili, Irakli; Martin, Nicole Alice; Martinengo, Paolo; Martinez Hernandez, Mario Ivan; Martinez-Garcia, Gines; Martin Blanco, Javier; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Massacrier, Laure Marie; Mastroserio, Annalisa; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel Anthony; Mazumder, Rakesh; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado-Perez, Jorge; Meres, Michal; Miake, Yasuo; Mikhaylov, Konstantin; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz Czeslaw; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Montes Prado, Esther; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Gameiro Munhoz, Marcelo; Murray, Sean; Musa, Luciano; Musinsky, Jan; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Nayak, Tapan Kumar; Nazarenko, Sergey; Nedosekin, Alexander; Nicassio, Maria; Niculescu, Mihai; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Nyanin, Alexander; Nyatha, Anitha; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Okatan, Ali; Olah, Laszlo; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Onderwaater, Jacobus; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pachr, Milos; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares Vales, Carlos; Pal, Susanta Kumar; Palmeri, Armando; Pant, Divyash; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woojin; Passfeld, Annika; Patalakha, Dmitry; Paticchio, Vincenzo; Paul, Biswarup; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitry Yurevich; Perez Lara, Carlos Eugenio; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Piyarathna, Danthasinghe; Planinic, Mirko; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Pohjoisaho, Esko Heikki Oskari; Polishchuk, Boris; Poljak, Nikola; Pop, Amalia; Porteboeuf, Sarah Julie; Porter, R Jefferson; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Punin, Valery; Putschke, Jorn Henning; Qvigstad, Henrik; Rachevski, Alexandre; Raha, Sibaji; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Rauf, Aamer Wali; Razazi, Vahedeh; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reed, Rosi Jan; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reicher, Martijn; Reidt, Felix; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riabov, Viktor; Ricci, Renato Angelo; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rivetti, Angelo; Rocco, Elena; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roeed, Ketil; Rogochaya, Elena; Sharma, Rohni; Rohr, David Michael; Roehrich, Dieter; Romita, Rosa; Ronchetti, Federico; Ronflette, Lucile; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roy, Ankhi; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Sadovskiy, Sergey; Safarik, Karel; Sahlmuller, Baldo; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Salgado Lopez, Carlos Alberto; Salzwedel, Jai Samuel Nielsen; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sanchez Rodriguez, Fernando Javier; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Santagati, Gianluca; Sarkar, Debojit; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schuchmann, Simone; Schukraft, Jurgen; Schulc, Martin; Schuster, Tim Robin; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca Michelle; Segato, Gianfranco; Seger, Janet Elizabeth; Selyuzhenkov, Ilya; Seo, Jeewon; Serradilla Rodriguez, Eulogio; Sevcenco, Adrian; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Shangaraev, Artem; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shtejer Diaz, Katherin; Sibiryak, Yury; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine Micaela; Simatovic, Goran; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sarkar - Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Soegaard, Carsten; Soltz, Ron Ariel; Song, Jihye; Song, Myunggeun; Soramel, Francesca; Sorensen, Soren Pontoppidan; Spacek, Michal; Sputowska, Iwona Anna; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Steinpreis, Matthew Donald; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strmen, Peter; Alarcon Do Passo Suaide, Alexandre; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Suleymanov, Mais Kazim Oglu; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Symons, Timothy; Szanto De Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szymanski, Maciej Pawel; Takahashi, Jun; Tangaro, Marco-Antonio; Tapia Takaki, Daniel Jesus; Tarantola Peloni, Attilio; Tarazona Martinez, Alfonso; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Ter-Minasyan, Astkhik; Thaeder, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony Robert; Toia, Alberica; Torii, Hisayuki; Trubnikov, Victor; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; Vande Vyvre, Pierre; Vannucci, Luigi; Van Hoorne, Jacobus Willem; Van Leeuwen, Marco; Diozcora Vargas Trevino, Aurora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara Limon, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Viinikainen, Jussi Samuli; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopyanov, Alexander; Volkl, Martin Andreas; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; Von Haller, Barthelemy; Vorobyev, Ivan; Vranic, Danilo; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Jan; Wagner, Vladimir; Wang, Mengliang; Wang, Yifei; Watanabe, Daisuke; Weber, Michael; Wessels, Johannes Peter; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Grzegorz Andrzej; Wilkinson, Jeremy John; Williams, Crispin; Windelband, Bernd Stefan; Winn, Michael Andreas; Xiang, Changzhou; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Ping; Yang, Shiming; Yano, Satoshi; Yasnopolskiy, Stanislav; Yi, Jungyu; Yin, Zhongbao; Yoo, In-Kwon; Yushmanov, Igor; Zaccolo, Valentina; Zach, Cenek; Zaman, Ali; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zavyalov, Nikolay; Zbroszczyk, Hanna Paulina; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Fan; Zhang, Haitao; Zhang, Xiaoming; Zhang, Yonghong; Zhao, Chengxin; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Hongsheng; Zhu, Jianhui; Zhu, Jianlin; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zimmermann, Markus Bernhard; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo; Zyzak, Maksym

    2014-02-26

    Correlations induced by quantum statistics are sensitive to the spatio-temporal extent as well as dynamics of particle emitting sources in heavy-ion collisions. In addition, such correlations can be used to search for the presence of a coherent component of pion production. Two and three-pion correlations of same and mixed-charge are measured at low relative momentum to estimate the coherent fraction of charged pions in Pb-Pb collisions at $\\sqrt{s_{NN}}$= 2.76 TeV at the LHC with ALICE. The genuine three-pion quantum statistics correlation is found to be suppressed relative to the two-pion correlation based on the assumption of fully chaotic pion emission.The suppression is observed to decrease with triplet momentum. The observed suppression at low triplet momentum may correspond to a coherent fraction in charged pion emission of 22% +- 12%.

  11. NEUTRAL PION EMISSION FROM ACCELERATED PROTONS IN THE SUPERNOVA REMNANT W44

    Energy Technology Data Exchange (ETDEWEB)

    Giuliani, A.; Caraveo, P.; Chen, A.; Contessi, T. [INAF-IASF Milano, via E. Bassini 15, 20133 Milano (Italy); Cardillo, M.; Tavani, M.; Costa, E.; Monte, E. Del; Donnarumma, I.; Evangelista, Y.; Feroci, M. [INAF/IASF-Roma,via Del Fosso del Cavaliere 100, 00133 Roma (Italy); Fukui, Y.; Yoshiike, S.; Torii, K. [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya 464-8602 (Japan); Dubner, G.; Castelletti, G. [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), 1428 Buenos Aires (Argentina); Barbiellini, G. [Dipartimento di Fisica and INFN, Via Valerio 2, I-34127 Trieste (Italy); Bulgarelli, A.; Gianotti, F. [INAF/IASF-Bologna, Via Gobetti 101, I-40129 Bologna (Italy); Cattaneo, P. W. [INFN-Pavia, Via Bassi 6, I-27100 Pavia (Italy); and others

    2011-12-15

    We present the AGILE gamma-ray observations in the energy range 50 MeV-10 GeV of the supernova remnant (SNR) W44, one of the most interesting systems for studying cosmic-ray production. W44 is an intermediate-age SNR ({approx}20, 000 years) and its ejecta expand in a dense medium as shown by a prominent radio shell, nearby molecular clouds, and bright [S II] emitting regions. We extend our gamma-ray analysis to energies substantially lower than previous measurements which could not conclusively establish the nature of the radiation. We find that gamma-ray emission matches remarkably well both the position and shape of the inner SNR shocked plasma. Furthermore, the gamma-ray spectrum shows a prominent peak near 1 GeV with a clear decrement at energies below a few hundreds of MeV as expected from neutral pion decay. Here we demonstrate that (1) hadron-dominated models are consistent with all W44 multiwavelength constraints derived from radio, optical, X-ray, and gamma-ray observations; (2) ad hoc lepton-dominated models fail to explain simultaneously the well-constrained gamma-ray and radio spectra, and require a circumstellar density much larger than the value derived from observations; and (3) the hadron energy spectrum is well described by a power law (with index s = 3.0 {+-} 0.1) and a low-energy cut-off at E{sub c} = 6 {+-} 1 GeV. Direct evidence for pion emission is then established in an SNR for the first time.

  12. Temporal and transverse coherence of self-amplified spontaneous emission

    International Nuclear Information System (INIS)

    Kim, K.J.

    1997-06-01

    The authors review the coherence properties of the self-amplified spontaneous emission (SASE). Temporally, SASE is similar to the spontaneous undulator radiation except that the spectral bandwidth is about ten times narrower compared with typical undulator radiation. The situation is quite different in the transverse dimension, where SASE is fully coherent

  13. Coherent single pion production by antineutrino charged current interactions and test of PCAC

    Science.gov (United States)

    Marage, P.; Aderholz, M.; Allport, P.; Armenise, N.; Baton, J. P.; Berggren, M.; Bertrand, D.; Brisson, V.; Bullock, F. W.; Burkot, W.; Calicchio, M.; Clayton, E. F.; Coghen, T.; Cooper-Sarkar, A. M.; Erriquez, O.; Fitch, P. J.; Gerbier, G.; Guy, J.; Hamisi, F.; Hulth, P. O.; Jones, G. T.; Kasper, P.; Klein, H.; Middleton, R. P.; Miller, D. B.; Mobayyen, M. M.; Morrison, D. R. O.; Natali, S.; Neveu, M.; O'Neale, S. W.; Parker, M. A.; Petiau, P.; Sacton, J.; Sansum, R. A.; Simopoulou, E.; Vallée, C.; Varvell, K.; Vayaki, A.; Venus, W.; Wachsmuth, H.; Wells, J.; Wittek, W.

    1986-06-01

    The cross section for coherent production of a single π- meson in charged current antineutrino interactions on neon nuclei has been measured in BEBC to be (175±25) 10-40 cm2/neon nucleus, averaged over the energy spectrum of the antineutrino wide band beam at the CERN SPS; this corresponds to (0.9±0.1) % of the total charged currentbar v_μ cross section. The distributions of kinematical variables are in agreement with theoretical predictions based on the PCAC hypothesis and the meson dominance model; in particular, the Q 2 dependence is well described by a propagator containing a mass m=(1.35±0.18) GeV. The absolute value of the cross section is also in agreement with the model. This analysis thus provides a test of the PCAC hypothesis in the antineutrino energy range 5 150 GeV.

  14. Coherent single pion production by antineutrino charged current interactions and test of PCAC

    International Nuclear Information System (INIS)

    Marage, P.; Bertrand, D.; Sacton, J.; Aderholz, M.; Wittek, W.; Allport, P.; Wells, J.; Baton, J.P.; Gerbier, G.; Neveu, M.; Clayton, E.F.; Hamisi, F.; Miller, D.B.; Mobayyen, M.M.; Cooper-Sarkar, A.M.; Guy, J.; Kasper, P.; Venus, W.; Klein, H.; Morrison, D.R.O.; Parker, M.A.; Wachsmuth, H.; Simopoulou, E.; Vayaki, A.

    1986-01-01

    The cross section for coherent production of a single π - meson in charged current antineutrino interactions on neon nuclei has been measured in BEBC to be (175+-25) 10 -40 cm 2 /neon nucleus, averaged over the energy spectrum of the antineutrino wide band beam at the CERN SPS; this corresponds to (0.9+-0.1)% of the total charged current anti νsub(μ) cross section. The distributions of kinematical variables are in agreement with theoretical predictions based on the PCAC hypothesis and the meson dominance model; in particular, the Q 2 dependence is well described by a propagator containing a mass m=(1.35+-0.18)GeV. The absolute value of the cross section is also in agreement with the model. This analysis thus provides a test of the PCAC hypothesis in the antineutrino energy range 5-150 GeV. (orig.)

  15. Coherent pion production in the 12C and 40Ca by the (3 He,tπ+) charge exchange reaction at 2 GeV

    International Nuclear Information System (INIS)

    Farhi, Laurent

    1997-01-01

    The coherent pion production process on nuclei is defined as the excitation of the first excited state of the nucleon, the delta(1232) resonance, creating a delta-hole state. This state propagates through the nuclear medium and then decays in a single pion, living the target nuclei in its ground state. In the nuclei, the attractive interaction between delta-hole states in the spin-longitudinal channel shifts down the effective mass of the delta and induces a collective state of excitation. The nuclear response in the longitudinal channel of interaction can be studied experimentally through the resonance decay coherent process triggered by a probe coupling longitudinally with the delta and selected by the target form factor. The ( 3 He, t) probe at 2 GeV on nuclei and the experimental set-up SPES IV-Pi have been used to study this decay process. A simulation program using GEANT and including theoretical consideration, knowledge of previous experimental results and the experimental properties of the set-up, have demonstrated the capability of the experiment for this study. The setting of the PCOS-IV acquisition system of multiwire proportional chambers and of the development and use of programs for treatment and analysis of experimental data have been necessary steps to make the experiment at Laboratoire National SATURNE as well as to obtain physical parameters in order to exhibit the coherent process. Nevertheless, the angular distribution of coherent pions differ from the theoretical predictions. Several hypotheses involving the experimental set-up and physical processes have been investigated in order to account for such distributions. (author)

  16. Femtosecond coherent emission from GaAs bulk microcavities

    Science.gov (United States)

    Gurioli, Massimo; Bogani, Franco; Ceccherini, Simone; Colocci, Marcello; Beltram, Fabio; Sorba, Lucia

    1999-02-01

    The emission from a λ/2 GaAs bulk microcavity resonantly excited by femtosecond pulses has been characterized by using an interferometric correlation technique. It is found that the emission is dominated by the coherent signal due to light elastically scattered by disorder, and that scattering is predominantly originated from the lower polariton branch.

  17. Kinetics of an expanding pion gas and low-mass dilepton emission

    International Nuclear Information System (INIS)

    Kaempfer, B.; Technische Univ. Dresden; Koch, P.; Pavlenko, O.P.; AN Ukrainskoj SSR, Kiev

    1993-03-01

    We study the space-time dependence of muon pair production from dense, non-equilibrium pion matter in the framework of a Boltzmann type transport model which properly includes effects of Bose statistics. Starting from an initially supersaturated pion gas with a large positive effective chemical potential we find that this pion chemical potential stays approximately constant during the evolution. As a consequence such a scenario leads to an increased dilepton yield near the kinematical threshold for muon pair production via pion annihilation. Depending on the lifetime of the dense hadron matter formed in relativistic heavy ion collisions, this component can e observed above the background of muon pair from resonance decays and the ρ,ωbump. In such a way the measurement of the di-muon invariant mass spectrum could help to understand the initial state and the dynamical evolution of ultrarelativistic heavy ion collisions. (orig.)

  18. Characteristics of the pion production and nucleon emission processes in pion-carbon nuclear collisions at 40 GeV/.c

    International Nuclear Information System (INIS)

    Strugalski, Z.; Sultanov, M.

    1992-01-01

    Experimental data on pion-carbon nucleus collisions are presented. The momentum and energy spectra of protons emitted from the target nucleus do not depend on the intensity of the pion production in the collisions. 6 refs.; 12 figs.; 12 tabs

  19. Pion, pion-pion, and pion-nucleus interactions

    CERN Document Server

    Mukhin, K N; Tikhonov, V N

    2002-01-01

    This survey is devoted to describing the early studies of 1.1. Gurevich on pion physics that were performed by the photoemulsion method and the studies of the pion-pion interaction that were made by his colleagues on the basis of the hydrogen-bubble-chamber and the magnetic-spectrometer method (as well-as on the basis of the photoemulsion method). Two approaches-an extrapolation of experimental data from the physical region to the pion pole and a theoretical calculation based on the Roy integral equations-are used to deduce information about the pion-pion interaction. The first results obtained for pion-pion and pion-nucleus interactions in the experiments that are being currently performed in Brookhaven and at CERN ( pi pi interaction) and at TRIUMF (Canada) and in Brookhaven (pion-nucleus interaction) are presented, along with the existing theoretical concepts in these realms of physics. (80 refs).

  20. Rho meson self-energy and dielectron emissivity in an isospin-asymmetric pion medium

    International Nuclear Information System (INIS)

    Gulamov, T.I.; Titov, A.I.; Forschungszentrum Rossendorf e.V.; Kaempfer, B.; Technische Univ., Dresden

    1995-06-01

    The ρ meson self-energy in an isospin asymmetric pion gas at finite temperature and charged-pion chemical potential is evaluated. We utilize a conventional effective π-ρ Lagrangian and the functional integral representation of the partition function in the second order in the ρππ coupling constant. We analyze the gauge invariant rho meson polarization operator and its dependence on the invariant mass M and spatial momentum vertical stroke pvertical stroke of the ρ meson. The pole positions and the values of the imaginary parts of the self-energy for different polarization states have different functional dependences on M and vertical stroke pvertical stroke . The corresponding dielectron rate (calculated from the imaginary part of the polarization operators) shows a distinctive asymmetry when the momentum t=p + -p - is perpendicular or parallel to p, where p ± are the momenta of the electron pair. (orig.)

  1. ρ-meson self-energy and dielectron emissivity in an isospin-asymmetric pion medium

    International Nuclear Information System (INIS)

    Titov, A.I.; Gulamov, T.I.; Kaempfer, B.

    1996-01-01

    The ρ-meson self-energy in an isospin-asymmetric pion gas at finite temperature and charged-pion chemical potential is evaluated. We utilize a conventional effective π-ρ Lagrangian and the functional integral representation of the partition function in the second order in the ρππ coupling constant. We analyze the ρ-meson polarization operator and its dependence on the invariant mass M and spatial momentum parallel p parallel of the ρ meson. The pole positions and the values of the imaginary parts of the self-energy for different polarization states have different functional dependences on M and parallel p parallel. The corresponding dielectron rate (calculated from the imaginary part of the in-medium ρ-meson propagator) shows a distinctive asymmetry when the momentum t=p + -p - is perpendicular or parallel to p, where p ± are the e ± momenta of the electron pair. copyright 1996 The American Physical Society

  2. Coherent pion production with the 910 MeV 3He beam at the CERN S.C

    International Nuclear Information System (INIS)

    Aslanides, E.

    1979-01-01

    The first experiment carried out at the CERN synchrocyclotron, 3 He + nucleus → X + π - , is analysed. The inclusive pion spectrum is given up to the kinematic limit covering cross sections from a few μb/sr MeV/C to 0.1 pb/sr MeV/C. An attempt is made to see how far these results are consistent with an interpretation based on the NN→NNπ process by means of nuclear form factors and by scaling [fr

  3. Coherent control of atto-second emission from aligned molecules

    Energy Technology Data Exchange (ETDEWEB)

    Boutu, W; Haessler, S; Merdji, H; Breger, P; Monchicourt, P; Carre, B; Salieres, P [CEA Saclay, DSM, Serv Photons Atomes Mol, F-91191 Gif Sur Yvette, (France); Waters, G [Univ Reading, JJ Thomson Phys Lab, Reading RG6 6AF, Berks, (United Kingdom); Stankiewicz, M [Jagiellonian Univ, Inst Phys, PL-30059 Krakow, (Poland); Frasinski, L J [Univ London Imperial Coll Sci Technol and Med, Blackett Lab, London SW7 2BW, (United Kingdom); Taieb, R; Caillat, J; Maquet, A [Univ Paris 06, UMR 7614, Lab Chim Phys Matiere Rayonnement, F-75231 Paris 05, (France); Taieb, R; Caillat, J; Maquet, A [LCPMR, UMR 7614, CNRS, F-75005 Paris, (France)

    2008-07-01

    Controlling atto-second electron wave packets and soft X-ray pulses represents a formidable challenge of general implication to many areas of science. A strong laser field interacting with atoms or molecules drives ultrafast intra-atomic/molecular electron wave packets on a sub femtosecond timescale, resulting in the emission of atto-second bursts of extreme-ultraviolet light. Controlling the intra-atomic/molecular electron dynamics enables steering of the atto-second emission. Here, we carry out a coherent control in linear molecules, where the interaction of the laser-driven electron wave packet with the core leads to quantum interferences. We demonstrate that these interferences can be finely controlled by turning the molecular axis relative to the laser polarization, that is, changing the electron re-collision angle. The wave-packet coulombic distortion modifies the spectral phase jump measured in the extreme-ultraviolet emission. Our atto-second control of the interference results in atto-second pulse shaping, useful for future applications in ultrafast coherent control of atomic and molecular processes. (authors)

  4. Emission of light charged particles from fragments produced on fission of uranium nuclei by 153 MeV protons and 1700 MeV negative pions

    International Nuclear Information System (INIS)

    Belovitzky, G.E.; Shteingrad, O.M.

    2000-01-01

    The mechanism underlying the emission of light charged particles (LCP) with Z = 1, 2 from fragments produced in fission of uranium nuclei by 153 MeV protons and 1700 MeV negative pions was studied. It was found that LCP accompanying the fission by pions are emitted from non-accelerated fragments immediately after the fission, whereas in the case of 153 MeV protons, the LCP are emitted from the accelerated heavy fragments. The number of LCP emitted in the course of pion-induced fission is 0.7 per fission event, which exceeds by a factor of 30 the corresponding number for 153 MeV protons [ru

  5. Coherent control of spontaneous emission near a photonic band edge

    International Nuclear Information System (INIS)

    Woldeyohannes, Mesfin; John, Sajeev

    2003-01-01

    We demonstrate the coherent control of spontaneous emission for a three-level atom located within a photonic band gap (PBG) material, with one resonant frequency near the edge of the PBG. Spontaneous emission from the three-level atom can be totally suppressed or strongly enhanced depending on the relative phase between the steady-state control laser coupling the two upper levels and the pump laser pulse used to create an excited state of the atom in the form of a coherent superposition of the two upper levels. Unlike the free-space case, the steady-state inversion of the atomic system is strongly dependent on the externally prescribed initial conditions. This non-zero steady-state population is achieved by virtue of the localization of light in the vicinity of the emitting atom. It is robust to decoherence effects provided that the Rabi frequency of the control laser field exceeds the rate of dephasing interactions. As a result, such a system may be relevant for a single-atom, phase-sensitive optical memory device on the atomic scale. The protected electric dipole within the PBG provides a basis for a qubit to encode information for quantum computations. A detailed literature survey on the nature, fabrication and applications of PBG materials is presented to provide context for this research. (phd tutorial)

  6. Coherent pion production in the {sup 12}C and {sup 40}Ca by the (3 He,t{pi}{sup +}) charge exchange reaction at 2 GeV; Production coherente de pions dans les noyaux {sup 12}C, {sup 40}Ca, par reaction d`echange de charge ({sup 3}He, t{pi}{sup +}) a 2 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Farhi, Laurent [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France)

    1997-10-13

    The coherent pion production process on nuclei is defined as the excitation of the first excited state of the nucleon, the delta(1232) resonance, creating a delta-hole state. This state propagates through the nuclear medium and then decays in a single pion, living the target nuclei in its ground state. In the nuclei, the attractive interaction between delta-hole states in the spin-longitudinal channel shifts down the effective mass of the delta and induces a collective state of excitation. The nuclear response in the longitudinal channel of interaction can be studied experimentally through the resonance decay coherent process triggered by a probe coupling longitudinally with the delta and selected by the target form factor. The ({sup 3}He, t) probe at 2 GeV on nuclei and the experimental set-up SPES IV-Pi have been used to study this decay process. A simulation program using GEANT and including theoretical consideration, knowledge of previous experimental results and the experimental properties of the set-up, have demonstrated the capability of the experiment for this study. The setting of the PCOS-IV acquisition system of multiwire proportional chambers and of the development and use of programs for treatment and analysis of experimental data have been necessary steps to make the experiment at Laboratoire National SATURNE as well as to obtain physical parameters in order to exhibit the coherent process. Nevertheless, the angular distribution of coherent pions differ from the theoretical predictions. Several hypotheses involving the experimental set-up and physical processes have been investigated in order to account for such distributions. (author) 44 refs., 68 figs., 7 tabs.

  7. Coherent vs Incoherent Emission from Semiconductor Structures after Resonant Femtosecond Excitation

    Science.gov (United States)

    Gurioli, Massimo; Bogani, Franco; Ceccherini, Simone; Colocci, Marcello

    1997-04-01

    We show that an interferometric correlation measurement with fs time resolution provides an unambiguous discrimination between coherent and incoherent emission after resonant femtosecond excitation. The experiment directly probes the most important difference between the two emissions, that is, the phase correlation with the excitation pulse. The comparison with cw frequency resolved measurements demonstrates that the relationship between coherent and incoherent emission is similar under femtosecond and steady-state excitation.

  8. Pion emission from the T2K replica target: method, results and application

    CERN Document Server

    Abgrall, N.; Anticic, T.; Antoniou, N.; Argyriades, J.; Baatar, B.; Blondel, A.; Blumer, J.; Bogomilov, M.; Bravar, A.; Brooks, W.; Brzychczyk, J.; Bubak, A.; Bunyatov, S.A.; Busygina, O.; Christakoglou, P.; Chung, P.; Czopowicz, T.; Davis, N.; Debieux, S.; Di Luise, S.; Dominik, W.; Dumarchez, J.; Dynowski, K.; Engel, R.; Ereditato, A.; Esposito, L.S.; Feofilov, G.A.; Fodor, Z.; Ferrero, A.; Fulop, A.; Gazdzicki, M.; Golubeva, M.; Grabez, B.; Grebieszkow, K.; Grzeszczuk, A.; Guber, F.; Haesler, A.; Hakobyan, H.; Hasegawa, T.; Idczak, R.; Igolkin, S.; Ivanov, Y.; Ivashkin, A.; Kadija, K.; Kapoyannis, A.; Katrynska, N.; Kielczewska, D.; Kikola, D.; Kirejczyk, M.; Kisiel, J.; Kiss, T.; Kleinfelder, S.; Kobayashi, T.; Kochebina, O.; Kolesnikov, V.I.; Kolev, D.; Kondratiev, V.P.; Korzenev, A.; Kowalski, S.; Krasnoperov, A.; Kuleshov, S.; Kurepin, A.; Lacey, R.; Larsen, D.; Laszlo, A.; Lyubushkin, V.V.; Mackowiak-Pawlowska, M.; Majka, Z.; Maksiak, B.; Malakhov, A.I.; Maletic, D.; Marchionni, A.; Marcinek, A.; Maris, I.; Marin, V.; Marton, K.; Matulewicz, T.; Matveev, V.; Melkumov, G.L.; Messina, M.; Mrowczynski, St.; Murphy, S.; Nakadaira, T.; Nishikawa, K.; Palczewski, T.; Palla, G.; Panagiotou, A.D.; Paul, T.; Peryt, W.; Petukhov, O.; Planeta, R.; Pluta, J.; Popov, B.A.; Posiadala, M.; Pulawski, S.; Puzovic, J.; Rauch, W.; Ravonel, M.; Renfordt, R.; Robert, A.; Rohrich, D.; Rondio, E.; Rossi, B.; Roth, M.; Rubbia, A.; Rustamov, A.; Rybczynski, M.; Sadovsky, A.; Sakashita, K.; Savic, M.; Sekiguchi, T.; Seyboth, P.; Shibata, M.; Sipos, M.; Skrzypczak, E.; Slodkowski, M.; Staszel, P.; Stefanek, G.; Stepaniak, J.; Strabel, C.; Strobele, H.; Susa, T.; Szuba, M.; Tada, M.; Taranenko, A.; Tereshchenko, V.; Tolyhi, T.; Tsenov, R.; Turko, L.; Ulrich, R.; Unger, M.; Vassiliou, M.; Veberic, D.; Vechernin, V.V.; Vesztergombi, G.; Wilczek, A.; Wlodarczyk, Z.; Wojtaszek-Szwarc, A.; Wyszynski, O.; Zambelli, L.; Zipper, W.; Hartz, M.; Ichikawa, A.K.; Kubo, H.; Marino, A.D.; Matsuoka, K.; Murakami, A.; Nakaya, T.; Suzuki, K.; Yuan, T.; Zimmerman, E.D.

    2013-01-01

    The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.

  9. Pion-pion interactions in particle physics

    Energy Technology Data Exchange (ETDEWEB)

    Martin, B R; Morgan, D; Shaw, G

    1976-01-01

    The aim of the book is to review the experimental and theoretical work on the processes involving pion-pion interactions. Sources of information on pion-pion scattering are examined, including pion production, dipion exchange, and weak and electromagnetic interactions. The theory and models of pion-pion scattering are discussed with reference to fixed momentum transfer, partial wave amplitudes, models and phenomenology, dynamical and field theoretic models, finite-energy sum rules, duality and the Veneziano model, resonance spectra and lastly, predictions from current algebra.

  10. Coherent changes of multifractal properties of continuous acoustic emission at failure of heterogeneous materials

    Science.gov (United States)

    Panteleev, Ivan; Bayandin, Yuriy; Naimark, Oleg

    2017-12-01

    This work performs a correlation analysis of the statistical properties of continuous acoustic emission recorded in different parts of marble and fiberglass laminate samples under quasi-static deformation. A spectral coherent measure of time series, which is a generalization of the squared coherence spectrum on a multidimensional series, was chosen. The spectral coherent measure was estimated in a sliding time window for two parameters of the acoustic emission multifractal singularity spectrum: the spectrum width and the generalized Hurst exponent realizing the maximum of the singularity spectrum. It is shown that the preparation of the macrofracture focus is accompanied by the synchronization (coherent behavior) of the statistical properties of acoustic emission in allocated frequency intervals.

  11. Ultrafast spectral interferometry of resonant secondary emission from quantum wells: From Rayleigh scattering to coherent emission from biexcitons

    DEFF Research Database (Denmark)

    Birkedal, Dan; Shah, Jagdeep; Pfeiffer, L. N.

    1999-01-01

    Recent investigations of secondary emission from quantum well excitons following ultrafast resonant excitation have demonstrated an intricate interplay of coherent Rayleigh scattering and incoherent luminescence. We have very recently demonstrated that it is possible to isolate and time resolve...... the coherent field associated with Rayleigh component using ultrafast spectral interferometry or Tadpole, thus, obtaining substantial and new information of the nature of resonant secondary emission. Our observation demonstrates that Rayleigh scattering from static disorder is inherently a non-ergodic process...... invalidating the use of current theories using ensemble averages to describe our observations. Furthermore, we report here a new and hitherto unknown coherent scattering mechanism involving the two-photon coherence associated with the biexciton transition. The process leaves an exciton behind taking up...

  12. Coherent secondary emission from resonantly excited two-exciton states

    DEFF Research Database (Denmark)

    Birkedal, Dan

    2000-01-01

    The coherent interaction of light and the electronic states of semiconductors near the fundamental bandgap has been a very active topic of research since the advent of ultrafast lasers. While many of the ultrafast nonlinear properties of semiconductors have been well explained within mean field...

  13. Timeresolved Speckle Analysis: Probing the Coherence of Excitonic Secondary Emission

    DEFF Research Database (Denmark)

    Langbein, Wolfgang; Hvam, Jørn Märcher; Zimmermann, R.

    1998-01-01

    in semiconductor quantum wells is investigated. Here, a partial coherence results from an interplay between scattering due to static disorder and inelastic relaxation, without any influence of the radiative decay. The temperature dependence is well explained by dephasing due to phonon scattering....

  14. Frequency dependence of coherently amplified two-photon emission from hydrogen molecules

    Science.gov (United States)

    Hara, Hideaki; Miyamoto, Yuki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

    2017-12-01

    We investigate how the efficiency of coherently amplified two-photon emission depends on the frequency of one of the two emitted photons, namely the signal photon. This is done over the wavelength range of 5.048-10.21 μ m by using the vibrational transition of parahydrogen. The efficiency increases with the frequency of the signal photon. Considering experimental errors, our results are consistent with the theoretical prediction for the present experimental conditions. This study is an experimental demonstration of the frequency dependence of coherently amplified two-photon emission, and also presents its potential as a light source.

  15. Reaction mechanisms in coherent nuclear photoproduction

    International Nuclear Information System (INIS)

    Lazard, C.

    Nuclear coherent pion photoproduction is studied. Pion rescattering and propagation effects inside nucleus and mesic exchange current effects are discussed. Influence of nuclear wave functions and Fermi motion is presented [fr

  16. One, two and three pion production in pd collisions at 19 GeV/c

    International Nuclear Information System (INIS)

    Bakken, V.; Jacobsen, T.; Olsson, J.E.; Johansson, H.; Lundborg, P.; Sellden, B.; Maekelae, J.; Pimiae, H.; Sundell, E.

    1976-04-01

    Cross sections for coherent and non-coherent production of one, two and three pions in pd reactions at 19 GeV/c are presented. The mass distribution of the two pion non-coherent channels are studied. Strong single Δ(1236) and also some double Δ production are observed. Clear evidence for rho production is seen. (Auth.)

  17. A theory of the coherent fundamental plasma emission in Tokamaks

    International Nuclear Information System (INIS)

    Alves, M.V.; Chian, A.C.-L.

    1987-01-01

    A theoretical model of coherent radiation near the fundamental plasma frequency in tokamaks is proposed. It is shown that, in the presence of runaway electrons, the beam-generated Langmuir waves (L) can be parametrically converted into electromagnetic waves (T) through ponderomotive coupling to ion acoustic waves (S). Two types of pumps are considered: travelling wave pump and standing wave pump. Expressions are derived for the excitation conditions and the growth rates of electromagnetic decay instabilities (L-> T + S), electromagnetic fusion instabilities (L + S -> T) and electromagnetic oscillating two-stream instabilities (L -> T+- S * , where S * is a purely growing mode). (author) [pt

  18. A theory of the coherent fundamental plasma emission in Tokamaks

    International Nuclear Information System (INIS)

    Alves, M.V.; Chian, A.C.-L.

    1987-07-01

    A theoretical model of coherent radiation near the fundamental plasma frequency in Tokamaks is proposed. It is shown that, in the presence of runaway electrons, the beam-generated Langmuir waves (L) can be paarmetrically converted into electromagnetic waves (T) through ponderomotive coupling to ion acoustic waves (S). Two types of pumps are considered: traveling wave and standing wave pump. Expressions are derived for the excitation conditions and the growth rates of electomagnetic decay instabilities (L → T + S), electromagnetic fusion instabilities (L + S → T) and electromagnetic oscillating two-stream instabilities (L → T+-S sup(*) is a purely growing mode). (author) [pt

  19. Zb(10 610) and Zb(10 650) structures produced by the initial single pion emission in the Υ(5S) decays

    International Nuclear Information System (INIS)

    Chen Dianyong; Liu Xiang

    2011-01-01

    We propose a unique mechanism called initial single pion emission existing in the Υ(5S) decays, and further study the line shapes of dΓ(Υ(5S→Υ(nS)π + π - ))/dm Υ(nS)π + (n=1,2,3) and dΓ(Υ(5S→h b (mP)π + π - ))/dm h b (mP)π + (m=1,2). We find sharp structures around 10 610 MeV and 10 650 MeV in the obtained theoretical line shapes of dΓ(Υ(5S→Υ(nS)π + π - ))/dm Υ(nS)π + and dΓ(Υ(5S→h b (mP)π + π - ))/dm h b (mP)π + distributions, which could naturally correspond to the Z b (10 610) and Z b (10 650) structures newly observed by Belle.

  20. Pion condensation and instabilities: current theory and experiment

    International Nuclear Information System (INIS)

    Gyulassy, M.

    1980-05-01

    Current calculations of pion condensation phenomena in symmetric nuclear matter are reviewed. The RPA and MFA methods are compared. Latest results [LBL-10572] with a relativistic MFA theory constrained by bulk nuclear properties are presented. The differences between equilibrium (condensation) and nonequilibrium (dynamic) instabilities are discussed. Finally, two-proton correlation experiments aimed at looking for critical scattering phenomena and two-pion correlation experiments aimed at looking for pion field coherence are analyzed. 10 figures, 2 tables

  1. Coherent manipulation of spontaneous emission spectra in coupled semiconductor quantum well structures.

    Science.gov (United States)

    Chen, Aixi

    2014-11-03

    In triple coupled semiconductor quantum well structures (SQWs) interacting with a coherent driving filed, a coherent coupling field and a weak probe field, spontaneous emission spectra are investigated. Our studies show emission spectra can easily be manipulated through changing the intensity of the driving and coupling field, detuning of the driving field. Some interesting physical phenomena such as spectral-line enhancement/suppression, spectral-line narrowing and spontaneous emission quenching may be obtained in our system. The theoretical studies of spontaneous emission spectra in SQWS have potential application in high-precision spectroscopy. Our studies are based on the real physical system [Appl. Phys. Lett.86(20), 201112 (2005)], and this scheme might be realizable with presently available techniques.

  2. High-order harmonic generation: A coherent ultrashort emission in the XUV range

    International Nuclear Information System (INIS)

    Salieres, Pascal; Hergott, Jean-Francois; Le Deroff, Laurent; Merdji, Hamed; Carre, Bertrand; Auguste, Thierry; Monot, Pascal; D'Oliveira, Pascal; Joyeux, Denis; Phalippou, Daniel

    2000-01-01

    We review the recent progress in theoretical and experimental understanding of harmonic generation by intense laser pulses. We present investigations on the spatial and temporal coherence properties of the harmonic emission, showing that they can be controlled. Finally, we give some examples of current applications of this XUV source, in particular in the diagnostic of dense plasmas

  3. Experimental study of the pion-xenon nucleus collisions at 3.5 GeV/c. Neutral pion production

    International Nuclear Information System (INIS)

    Strugalski, Z.; Abrosimov, A.T.; Wosinska, K.; Pawlak, T.; Nluta, J.; Sredniawa, B.; Il'ina, A.N.; Okhrimenko, L.S.; Peryt, W.; Miller, K.

    1983-01-01

    Experimental investigations of the neutral pion production are performed in pion-xenon collisions at 3.5 GeV/c. It is obtained that: 1) the average neutral pion multiplicity changes with the multiplicity of the protons emitted; 2) nearly 20% of the pions produced are emitted into the backward hemisphere; 3) the energy spectrum of the neutral pions is smooth; 4) the longitudinal component of the neutral pion momentum changes within the limits from -600 MeV/c to +1800 MeV/c; 5) the average value of the transversal component of the neutral pion momentum changes with the multiplicity of the protons emitted from approximately 270 to approximately 170 MeV/c; 6) the average value of the cosine of the neutral pion emission angle decreases with the multiplicity of the protons emitted

  4. Self-amplified spontaneous emission for short wavelength coherent radiation

    International Nuclear Information System (INIS)

    Kim, K.J.; Xie, M.

    1992-09-01

    We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented

  5. Coherent emission from relativistic beam-plasma interactions

    International Nuclear Information System (INIS)

    Latham, P.E.

    1986-01-01

    A theoretical model for the production of high-power, high-frequency electromagnetic radiation from unmagnetized, relativistic beam-plasma interactions is studied. Emphasis is placed on the injected-beam system, for which the dominant portion of the radiation is emitted near the point where the beam enters the plasma. In such systems, frequencies much larger than the plasma frequency and power levels many orders of magnitude above that predicted by single-particle radiation have been observed experimentally. A two-step process is proposed to explain these observations: electrostatic bunching of the beam followed by coherent radiation by the bunches. The first step, beam bunching, produces large-amplitude electrostatic waves. A Green's function analysis is employed to understand the convective growth of those waves near the plasma boundary; their saturation amplitude is found by applying conservation of energy to the beam-plasma system. An azimuthally symmetric model is used to compute the saturated spectrum analytically, and a relatively simple expression is found. The second step, the interaction of the electron beam with the electrostatic spectrum, leads to the production of high-power, high-frequency electromagnetic radiation. From a detailed analysis of the phase-space evolution of the trapped beam, an analytic expression for the electromagnetic spectrum is found as a function of angle and frequency

  6. Disoriented chiral condensates and anomalous production of pions

    International Nuclear Information System (INIS)

    Martinis, M.; Mikuta-Martinis, V.; Crnugelj, J.

    1999-01-01

    The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to study semiclassical production of pions in the central region. The mechanism is related to the isospin-uniform solution of the nonlinear σ-model coupled to quark degrees of freedom. The multipion exchange potential between two quarks is derived. It is shown that the soft chiral pion Bremsstrahlung also leads to anomalously large fluctuations in the ratio of neutral to charged pion.. We show that only direct production of pions in the form of an isoscalar coherent pulse without isovector pairs can lead to large neutral-charged fluctuations. (Authors)

  7. The influence of biomass energy consumption on CO2 emissions: a wavelet coherence approach.

    Science.gov (United States)

    Bilgili, Faik; Öztürk, İlhan; Koçak, Emrah; Bulut, Ümit; Pamuk, Yalçın; Muğaloğlu, Erhan; Bağlıtaş, Hayriye H

    2016-10-01

    In terms of today, one may argue, throughout observations from energy literature papers, that (i) one of the main contributors of the global warming is carbon dioxide emissions, (ii) the fossil fuel energy usage greatly contributes to the carbon dioxide emissions, and (iii) the simulations from energy models attract the attention of policy makers to renewable energy as alternative energy source to mitigate the carbon dioxide emissions. Although there appears to be intensive renewable energy works in the related literature regarding renewables' efficiency/impact on environmental quality, a researcher might still need to follow further studies to review the significance of renewables in the environment since (i) the existing seminal papers employ time series models and/or panel data models or some other statistical observation to detect the role of renewables in the environment and (ii) existing papers consider mostly aggregated renewable energy source rather than examining the major component(s) of aggregated renewables. This paper attempted to examine clearly the impact of biomass on carbon dioxide emissions in detail through time series and frequency analyses. Hence, the paper follows wavelet coherence analyses. The data covers the US monthly observations ranging from 1984:1 to 2015 for the variables of total energy carbon dioxide emissions, biomass energy consumption, coal consumption, petroleum consumption, and natural gas consumption. The paper thus, throughout wavelet coherence and wavelet partial coherence analyses, observes frequency properties as well as time series properties of relevant variables to reveal the possible significant influence of biomass usage on the emissions in the USA in both the short-term and the long-term cycles. The paper also reveals, finally, that the biomass consumption mitigates CO2 emissions in the long run cycles after the year 2005 in the USA.

  8. Polarization of the coherent radio emission from pulsars

    International Nuclear Information System (INIS)

    Ardavan, H.

    1982-01-01

    The polarization characteristics of the radiation from a quasi-steady pulsar magnetosphere are calculated using the amplitude-modulated-noise interpretation of the data on pulse structures. The total emission consists of three incoherently mixed radiation streams. Two of the independent polarization states are elliptically polarized (modes I and II) and one is linearly polarized (mode III). In the regime where the length scale of the radial distribution of the electric current density is appreciably longer than the wavelength of the radiation, the position angles of modes I and II are orthogonal and those of modes I and III coincident. However, the senses of circular polarization of modes I and II are in general uncorrelated. The degrees of circular polarization of the 'orthogonal' modes are decreasing functions of frequency and both approach zero in the limit where the frequency of the radiation is much higher than the rotation frequency of the pulsar. Longitudinal changes in the position angle and in the sense of circular polarization of each of the elliptically polarized modes are shown to arise, together with mode transitions, in part from the stochastic fluctuations and in part from the systematic variations of the electric current density with the azimuthal angle, in a narrow emitting region adjacent to the light cylinder. (author)

  9. Dosimetry of pion beams

    International Nuclear Information System (INIS)

    Dicello, J.F.

    1975-01-01

    Negative pion beams are probably the most esoteric and most complicated type of radiation which has been suggested for use in clinical radiotherapy. Because of the limited availability of pion beams in the past, even to nuclear physicists, there exist relatively fewer basic data for this modality. Pion dosimetry is discussed

  10. Coherent versus incoherent resonant emission: an experimental method for easy discrimination and measurement

    Science.gov (United States)

    Ceccherini, S.; Colocci, M.; Gurioli, M.; Bogani, F.

    1998-11-01

    The distinction between the coherent and the incoherent component of the radiation emitted from resonantly excited material systems is difficult experimentally, particularly when ultra-short optical pulses are used for excitation. We propose an experimental procedure allowing an easy measurement of the two components. The method is completely general and applicable to any kind of physical system; its feasibility is demonstrated on the resonant emission from excitons in a semiconductor quantum well.

  11. Spectrally tunable mollow triplet emission from a coherently excited quantum dot in a microcavity

    DEFF Research Database (Denmark)

    Ulrich, Sven M.; Ates, Serkan; Reitzenstein, Stephan

    2010-01-01

    Resonance fluorescence of excitonic s-shell emission from a coherently pumped single InGaAs/GaAs quantum dot inside a micropillar cavity has been investigated in dependence on optical pump power and laser detuning, respectively. For strong purely resonant excitation, Mollow triplet spectra with l...... with large Rabi splittings of j~­j » 60¹eV have been observed. Laser detuning-dependent series revealed the pronounced asymmetry of the emission triplet as predicted by theory. From our data, an electrical dipole moment of ¹ » 17:8§0:5 Debye could be derived for the excitonic state....

  12. Measuring the coherence properties of light emission from laser-plasma interactions. Final report

    International Nuclear Information System (INIS)

    Batha, S.H.

    1998-01-01

    Several detrimental instabilities can be excited when a high-intensity laser interacts with plasma. The temporal evolution and spectra of the scattered light emitted by many of these instabilities are used to characterize the instabilities and to benchmark theories. It has been difficult to image the emission region with sufficient resolution to make quantitative comparisons with theory. Direct measurement of the emission region would yield information on ponderomotive steepening phenomena, the true emission zone of convective instabilities, and on the saturation of absolute instabilities. The increase in laser intensity caused by the filamentation instability is conjectured to elevate the levels of parametric instabilities found in high-energy laser-plasma interactions. Because the diameter of the filaments is very small (on the order of 10 microm), it is impossible to image the emission sites directly and either to prove or to disprove this conjecture. The research reported here examines an alternate method of measuring the emission region of scattered light from parametric instabilities. This report provides a brief background of coherence theory by defining the relevant parameters in Section 2. A concrete example of the effect that multiple scattering sites would have on the proposed measurement is provided in Section 3. The following section briefly describes experiments that might be able to demonstrate the proposed technique. The conclusion raises the issue of coherence and its effect on the expected angular distribution of scattering light from parametric instabilities

  13. Spontaneous emission spectra and simulating multiple spontaneous generation coherence in a five-level atomic medium

    International Nuclear Information System (INIS)

    Li Jiahua; Liu Jibing; Qi Chunchao; Chen Aixi

    2006-01-01

    We investigate the features of the spontaneous emission spectra in a coherently driven cold five-level atomic system by means of a radio frequency (rf) or microwave field driving a hyperfine transition within the ground state. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized by modulating the frequency and intensity of the rf-driving field in our system. In the dressed-state picture of the coupling and rf-driving fields, we find that this coherently driven atomic system has three close-lying levels so that multiple spontaneously generated coherence (SGC) arises. Our considered atomic model can be found in real atoms, such as rubidium or sodium, so a corresponding experiment can be done to observe the expected phenomena related to SGC reported by Fountoulakis et al. [Phys. Rev. A 73, 033811 (2006)], since no rigorous conditions are required

  14. Continuously tunable sub-half-wavelength localization via coherent control of spontaneous emission

    International Nuclear Information System (INIS)

    Wang Fei; Tan Xin-Yu; Gong Cheng; Shi Wen-Xing

    2012-01-01

    We propose a continuously tunable method of sub-half-wavelength localization via the coherent control of the spontaneous emission of a four-level Y-type atomic system, which is coupled to three strong coupling fields including a standing-wave field together with a weak probe field. It is shown that the sub-half-wavelength atomic localization is realized for both resonance and off-resonance cases. Furthermore, by varying the probe detuning in succession, the positions of the two localization peaks are tuned continuously within a wide range of probe field frequencies, which provides convenience for the realization of sub-half-wavelength atomic localization experimentally

  15. Coherent detection of THz-induced sideband emission from excitons in the nonperturbative regime

    Science.gov (United States)

    Uchida, K.; Otobe, T.; Mochizuki, T.; Kim, C.; Yoshita, M.; Tanaka, K.; Akiyama, H.; Pfeiffer, L. N.; West, K. W.; Hirori, H.

    2018-04-01

    Strong interaction of a terahertz (THz) wave with excitons induces nonperturbative optical effects such as Rabi splitting and high-order sideband generation. Here, we investigated coherent properties of THz-induced sideband emissions from GaAs/AlGaAs multiquantum wells. With increasing THz electric field, optical susceptibility of the THz-dressed exciton shows a redshift with spectral broadening and extraordinary phase shift. This implies that the field ionization of the 1 s exciton modifies the THz-dressed exciton in the nonperturbative regime.

  16. Characteristic aspects of pion-condensed phases

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki; Tamagaki, Ryozo; Tatsumi, Toshitaka.

    1993-01-01

    Characteristic aspects of pion-condensed phases are described in a simple model, for the system involving only nucleons and pions which interact through the π-N P-wave interaction. We consider one typical version in each of three kinds of pion condensation; the one of neutral pions (π 0 ), the one of charged pions (π C ) and the combined one in which both the π 0 and π C condensations are coexistent. Emphasis is put on the description to clarify the novel structures of the nucleon system which are realized in the pion-condensed phases. At first, it is shown that the π 0 condensation is equivalent to the particular nucleonic phase realized by a structure change of the nucleon system, where the attractive first-order effect of the one-pion-exchange (OPE) tensor force is brought about coherently. The aspects of this phase are characterized by the layered structure with a specific spin-isospin order with one-dimensional localization (named the ALS structure in short), which provides the source function for the condensed π 0 field. We utilize both descriptions with use of fields and potentials for the π 0 condensation. Next, the π C condensation realized in neutron-rich matter is described by adopting a version of the traveling condensed wave. In this phase, the nucleonic structure becomes the Fermi gas consisting of quasi-neutrons described by a superposition of neutron and proton. In this sense the structure change of the nucleon system for the π C condensation is moderate, and the field description is suitable. Finally, we describe a coexistent pion condensation, in which both the π 0 and π C condensations coexist without interference in such a manner that the π C condensation develops in the ALS structure. The model adopted here provides us with the characteristic aspects of the pion-condensed phases persisting in the realistic situation, where other ingredients affecting the pion condensation are taken into account. (author)

  17. Coherent effects on two-photon correlation and directional emission of two two-level atoms

    International Nuclear Information System (INIS)

    Ooi, C. H. Raymond; Kim, Byung-Gyu; Lee, Hai-Woong

    2007-01-01

    Sub- and superradiant dynamics of spontaneously decaying atoms are manifestations of collective many-body systems. We study the internal dynamics and the radiation properties of two atoms in free space. Interesting results are obtained when the atoms are separated by less than half a wavelength of the atomic transition, where the dipole-dipole interaction gives rise to new coherent effects, such as (a) coherence between two intermediate collective states, (b) oscillations in the two-photon correlation G (2) , (c) emission of two photons by one atom, and (d) the loss of directional correlation. We compare the population dynamics during the two-photon emission process with the dynamics of single-photon emission in the cases of a Λ and a V scheme. We compute the temporal correlation and angular correlation of two successively emitted photons using the G (2) for different values of atomic separation. We find antibunching when the atomic separation is a quarter wavelength λ/4. Oscillations in the temporal correlation provide a useful feature for measuring subwavelength atomic separation. Strong directional correlation between two emitted photons is found for atomic separation larger than a wavelength. We also compare the directionality of a photon spontaneously emitted by the two atoms prepared in phased-symmetric and phased-antisymmetric entangled states vertical bar ±> k 0 =e ik 0 ·r 1 vertical bar a 1 ,b 2 >±e ik 0 ·r 2 vertical bar b 1 ,a 2 > by a laser pulse with wave vector k 0 . Photon emission is directionally suppressed along k 0 for the phased-antisymmetric state. The directionality ceases for interatomic distances less than λ/2

  18. Magnetic polarizability of pion

    Energy Technology Data Exchange (ETDEWEB)

    Luschevskaya, E.V., E-mail: luschevskaya@itep.ru [Institute for Theoretical and Experimental Physics, Bolshaia Cheremushkinskaia 25, 117218 Moscow (Russian Federation); School of Biomedicine, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Solovjeva, O.E., E-mail: olga.solovjeva@itep.ru [Institute for Theoretical and Experimental Physics, Bolshaia Cheremushkinskaia 25, 117218 Moscow (Russian Federation); Teryaev, O.V., E-mail: teryaev@theor.jinr.ru [Joint Institute for Nuclear Research, Dubna, 141980 (Russian Federation); National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute), Kashirskoe highway, 31, 115409 Moscow (Russian Federation)

    2016-10-10

    We explore the energy dependence of π mesons off the background Abelian magnetic field on the base of quenched SU(3) lattice gauge theory and calculate the magnetic dipole polarizability of charged and neutral pions for various lattice volumes and lattice spacings. The contribution of the magnetic hyperpolarizability to the neutral pion energy has been also found.

  19. Pion nucleus scattering lengths

    International Nuclear Information System (INIS)

    Huang, W.T.; Levinson, C.A.; Banerjee, M.K.

    1971-09-01

    Soft pion theory and the Fubini-Furlan mass dispersion relations have been used to analyze the pion nucleon scattering lengths and obtain a value for the sigma commutator term. With this value and using the same principles, scattering lengths have been predicted for nuclei with mass number ranging from 6 to 23. Agreement with experiment is very good. For those who believe in the Gell-Mann-Levy sigma model, the evaluation of the commutator yields the value 0.26(m/sub σ//m/sub π/) 2 for the sigma nucleon coupling constant. The large dispersive corrections for the isosymmetric case implies that the basic idea behind many of the soft pion calculations, namely, slow variation of matrix elements from the soft pion limit to the physical pion mass, is not correct. 11 refs., 1 fig., 3 tabs

  20. Pions scatter by nuclei

    International Nuclear Information System (INIS)

    Huefner, J.

    1975-01-01

    Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties

  1. Electron emission induced by resonant coherent interaction in ion-surface scattering at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1994-01-01

    The resonant coherent interaction of an ion with an oriented crystal surface, under grazing-incidence conditions with respect to a special direction of the crystal, gives rise to electron loss to the continuum from electronic bound states of the ion. The calculations presented below predict large probabilities for electron emission due to this mechanism. The electrons are emitted with well defined energies, expressed in terms of the condition of resonance. Furthermore, the emission takes place around certain preferential directions, which are determined by both the latter condition and the symmetry of the surface lattice. Our calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with glancing angle of 0--2 mrad indicate a yield of emission close to 1. Using heavier projectiles, one obtains smaller yields, but still large enough to be measurable in some cases (e.g., ∼0.9 for 53 MeV B 4+ and an angle of incidence of 1 mrad). Besides, the initial bound state is energy shifted due to the interaction with both the crystal potential and the velocity-dependent image potential. This results in a slight shift of the peaks of emission, which suggests a possible spectroscopy for analyzing the dynamical interaction of electronic bound states with solid surfaces

  2. Virtual-pion and two-photon production in pp scattering

    International Nuclear Information System (INIS)

    Scholten, O.; Korchin, A.Yu.

    2002-01-01

    Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contributions. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

  3. Criterion of transverse coherence of self-amplified spontaneous emission in high gain free electron laser amplifiers

    International Nuclear Information System (INIS)

    Xie, M.; Kim, K.J.

    1995-01-01

    In a high gain free electron laser amplifier based on Self-Amplified Spontaneous Emission (SASE) the spontaneous radiation generated by an electron beam near the undulator entrance is amplified many orders of magnitude along the undulator. The transverse coherence properties of the amplified radiation depends on both the amplification process and the coherence of the seed radiation (the undulator radiation generated in the first gain length or so). The evolution of the transverse coherence in the amplification process is studied based on the solution of the coupled Maxwell-Vlasov equations including higher order transverse modes. The coherence of the seed radiation is determined by the number of coherent modes in the phase space area of the undulator radiation. We discuss the criterion of transverse coherence and identify governing parameters over a broad range of parameters. In particular we re-examine the well known emittance criterion for the undulator radiation, which states that full transverse coherence is guaranteed if the rms emittance is smaller than the wavelength divided by 4π. It is found that this criterion is modified for SASE because of the different optimization conditions required for the electron beam. Our analysis is a generalization of the previous study by Yu and Krinsky for the case of vanishing emittance with parallel electron beam. Understanding the transverse coherence of SASE is important for the X-ray free electron laser projects now under consideration at SLAC and DESY

  4. Pion observables and QCD

    International Nuclear Information System (INIS)

    Roberts, C.D.

    1995-01-01

    Herein the application of the DSE approach to the calculation of pion observables is described using: the π-π scattering lengths (a 0 0 , a 2 0 , a 1 1 , a 0 2 , a 2 2 ) and associated partial wave amplitudes; the π 0 → γγ decay width; and the charged pion form factor, F π (q 2 ), as illustrative examples. Since this approach provides a straightforward, microscopic description of dynamical chiral symmetry breaking (DχSB) and confinement, the calculation of pion observables is a simple and elegant illustrative example of its power and efficacy. (orig.)

  5. Pion double charge exchange

    International Nuclear Information System (INIS)

    Cooper, M.D.

    1978-01-01

    The pion double charge exchange data on the oxygen isotopes is reviewed and new data on 9 Be, 12 C, 24 Mg, and 28 Si are presented. Where theoretical calculations exist, they are compared to the data. 9 references

  6. Pion in a box

    International Nuclear Information System (INIS)

    Bietenholz, W.; Rakow, P.E.L.; Schierholz, G.; Regensburg Univ.

    2010-02-01

    The residual mass of the pion in a finite spatial box at vanishing quark masses is computed with two flavors of dynamical clover fermions. The result is compared with predictions of chiral perturbation theory in the δ regime. (orig.)

  7. Pion production in nuclei

    International Nuclear Information System (INIS)

    Afnan, I.R.; Thomas, A.W.

    1976-01-01

    A method has been suggested for relating μ-capture in nuclei to pion absorption through partially conserved axial vector current hypothesis. The success of the method relies heavily on the knowledge of the pion absorption amplitude at a momentum transfer equal to the μ-meson mass. That is we need to know the pion absorption amplitude off the mass-shell. The simplest nucleus for which this suggestion can be examined is μ-capture in deuterium. The Koltum-Reitan model is used to determine the pion absorption amplitude off the mass shell. In particular the senstivity of this off-mass-shell extrapolution to details of the N-N interaction is studied. (author)

  8. Study of the incident pion deflection in passing through atomic nucleus

    International Nuclear Information System (INIS)

    Strugalski, Z.; Pawlak, T.; Pluta, J.

    1982-01-01

    Pion-xenon nucleus collision events at 3.5 GeV/c momentum are studied in which the incident pion is deflected only, without particle production; the deflection is accompanied by emission of nucleons. The multiplicity of the protons emitted is a measure of the nuclear matter layer thickness passed by the pion. It can be concluded that: a) a definite simple relation exists between the pion deflection angle and the thickness of the nuclear matter layer traversed by this pion; b) the deflection angle of the incident pion increases in a definite manner with increasing the thickness of the nuclear matter layer traversed by this pion; c) the average kinetic energy, average longitudinal momentum and average transverse momentum of the protons emitted do not depend on the pion deflection angle

  9. Stimulated-emission pumping enabling sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering microscopy

    NARCIS (Netherlands)

    Cleff, C.; Gross, P.; Fallnich, C.; Offerhaus, Herman L.; Herek, Jennifer Lynn; Kruse, K.; Beeker, W.P.; Lee, Christopher James; Boller, Klaus J.

    2013-01-01

    We present a theoretical investigation of stimulated emission pumping to achieve sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering (CARS) microscopy. A pair of control light fields is used to prepopulate the Raman state involved in the CARS process prior to the CARS

  10. Coherent properties of single quantum dot transitions and single photon emission

    Energy Technology Data Exchange (ETDEWEB)

    Ester, Patrick

    2008-04-23

    of the first laser pulse. The relative phase of the QDs exciton can be controlled externally via the bias voltage. This effect is the basis for the observation of RAMSEY-fringes, which are presented in this work. The coherent manipulation of the p-shell is the basis for a novel excitation scheme for single photon emission. In this work it is shown that the first excited state can be coherently manipulated, similar to the ground state. (orig.)

  11. Coherent properties of single quantum dot transitions and single photon emission

    International Nuclear Information System (INIS)

    Ester, Patrick

    2008-01-01

    of the first laser pulse. The relative phase of the QDs exciton can be controlled externally via the bias voltage. This effect is the basis for the observation of RAMSEY-fringes, which are presented in this work. The coherent manipulation of the p-shell is the basis for a novel excitation scheme for single photon emission. In this work it is shown that the first excited state can be coherently manipulated, similar to the ground state. (orig.)

  12. Pion-nucleus scatter and the Pauli principle

    International Nuclear Information System (INIS)

    Dover, C.B.; Lemmer, R.H.

    1976-01-01

    A density expansion of the pion self-energy for pions in nuclear matter is reexamined. It is shown that a single hole-line expansion of the self-energy (i) is equivalent to using a strongly quenched πN scattering amplitude in the medium, and (ii) results in an inconsistent treatment of the virtual pions necessarily present in a field-theoretic description of the problem. Exchange of intermediate pions gives rise to nucleon-nucleon, as well as pion-nucleon scattering diagrams that both contribute to the pion self-energy in an essential way. The nucleon-nucleon scattering proceeds, for instance, via a one-pion-exchange potential that is, however, highly nonstatic for energy transfers between nucleons close to the incident energy. Such interactions are singled out automatically for special treatment in a field-theory approach to the problem, and should not be introduced in an ad hoc manner as part of an empirical NN interaction in nuclear matter. We evaluate the coherent and charge exchange contributions to the pion-nucleus optical potential, proportional to the total density and the neutron-proton density difference, respectively. The Pauli principle is found to provide a small correction to the coherent part, both in the hole-line and density expansion formalisms. However, the charge exchange part of the potential is almost completely damped at low energies in the hole-line expansion, while the inclusion of backward-going graphs (random-phase-approximation-type correlations) restores it to its value based on free space πN charge exchange amplitudes (i.e., no net Pauli effect)

  13. Effect of atomic-state coherence and spontaneous emission on three-level dynamics

    International Nuclear Information System (INIS)

    Cardimona, D.A.

    1990-01-01

    For a three-level atom in the ssV configuration (i.e., having two excited states each dipole-coupled to a common ground state), we have found a particular linear combination of bare-atom states in which Rabi oscillations and their associated collapses and revivals do not occur. Moving to a dressed-state picture, we discover that this particular linear combination state is just that dressed state which is decoupled from all the field modes. It is a dressed state for which the transition dipole moments with the other dressed states are zero. The existence of this decoupled dressed state depends on the tuning of the dressing laser field, which in turn depends on the bare-atom excited-state dipole moments and energy-level separation. When we include spontaneous emission, the population decays from the other dressed states into this decoupled state and remains coherently trapped there, producing a system that experiences no dynamical behavior. This is exact for δ-function photon statistics (i.e., if there is no intensity uncertainty). The trapping becomes less perfect as the photon statistics are allowed to have a greater bandwidth. Also, if the applied field is tuned incorrectly, the spontaneous realignment of the atomic state amplitudes does not result in a totally decoupled dressed state, and the dynamics proceed normally

  14. Vibrational motions associated with primary processes in bacteriorhodopsin studied by coherent infrared emission spectroscopy.

    Science.gov (United States)

    Groma, Géza I; Colonna, Anne; Martin, Jean-Louis; Vos, Marten H

    2011-03-16

    The primary energetic processes driving the functional proton pump of bacteriorhodopsin take place in the form of complex molecular dynamic events after excitation of the retinal chromophore into the Franck-Condon state. These early events include a strong electronic polarization, skeletal stretching, and all-trans-to-13-cis isomerization upon formation of the J intermediate. The effectiveness of the photoreaction is ensured by a conical intersection between the electronic excited and ground states, providing highly nonadiabatic coupling to nuclear motions. Here, we study real-time vibrational coherences associated with these motions by analyzing light-induced infrared emission from oriented purple membranes in the 750-1400 cm(-)(1) region. The experimental technique applied is based on second-order femtosecond difference frequency generation on macroscopically ordered samples that also yield information on phase and direction of the underlying motions. Concerted use of several analysis methods resulted in the isolation and characterization of seven different vibrational modes, assigned as C-C stretches, out-of-plane methyl rocks, and hydrogen out-of-plane wags, whereas no in-plane H rock was found. Based on their lifetimes and several other criteria, we deduce that the majority of the observed modes take place on the potential energy surface of the excited electronic state. In particular, the direction sensitivity provides experimental evidence for large intermediate distortions of the retinal plane during the excited-state isomerization process. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. The expanding pion liquid and the pion spectra

    International Nuclear Information System (INIS)

    Ayala, A.

    1999-01-01

    We compute the pion inclusive momentum distribution in heavy-ion collisions for energies at the Alternating Gradient Synchrotron (AGS), assuming thermal equilibrium and accounting for density and expansion effects at freeze out. We compare to data on mid-rapidity charged pions produced in central Au + Au collisions and find a very good agreement. The shape of the distribution at low transverse mass is explained in part as an effect arising from the high mean pion density achieved in these reactions. The difference between the positive and negative pion distributions in the same region is attributed in part to the different average yields of each kind of charged pions. (Author)

  16. New ultrafast X-ray sources and their applications. Coherent ultrashort X UV emission by harmonic generation

    International Nuclear Information System (INIS)

    Salieres, P.; Le deroff, L.; Hergott, J.F.; Merdji, H.; Carre, B.

    2000-01-01

    By focusing an intense short-pulse laser into a rare gas jet, high-order harmonics of the laser frequency are generated. Considerable progress have been made in the last few years, with the observation of harmonic orders higher that 200, extending the emission down to 3 nm. Besides its fundamental interest, this XUV emission represents a new source with unique properties of coherence and ultrashort (femtosecond) duration. A growing number of applications are reported, ranging from atomic and molecular spectroscopy to solid-state and plasma physics. (authors)

  17. Examination of ceramic/enamel interfacial debonding using acoustic emission and optical coherence tomography.

    Science.gov (United States)

    Lin, Chun-Li; Kuo, Wen-Chuan; Chang, Yen-Hsiang; Yu, Jin-Jie; Lin, Yun-Chu

    2014-08-01

    This study investigates monitored micro-crack growth and damage in the ceramic/enamel adhesive interface using the acoustic emission (AE) technique with optical coherence tomography (OCT) under fatigue shear testing. Shear bond strength (SBS) was measured first with eight prepared ceramic/enamel adhesive specimens under static loads. The fatigue shear testing was performed with three specimens at each cyclic load according to a modified ISO14801 method, applying at 80%, 75%, 70%, and 65% of the SBS to monitor interface debonding. The number of cycles at each load was recorded until ceramic/enamel adhesive interface debonding occurred. The AE technique was used to detect micro-crack signals in static and fatigue shear bond tests. The results showed that the average SBS value in the static tests was 18.07 ± 1.72 MPa (mean ± standard deviation), expressed in Newton's at 56.77 ± 5.40N. The average number of fatigue cycles in which ceramic/enamel interface damage was detected in 80%, 75%, 70% and 65% of the SBS were 41, 410, 8141 and 76,541, respectively. The acoustic behavior varied according to the applied load level. Events were emitted during 65% and 70% fatigue tests. A good correlation was observed between the crack location in OCT images and the number of AE signal hits. The AE technique combined with OCT images as a pre-clinical assessment tool to determine the integrity of cemented load bearing restored ceramic material. Sustainable cyclic load stresses in ceramic/enamel bonded specimens were substantially lower than the measured SBS. Predicted S-N curve showed that the maximum endured load was 10.98 MPa (about 34.48 N) passing 10(6) fatigue cyclic. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Azimuthal dependence of pion source radii in Pb + Au collisions at 158 A GeV

    CERN Document Server

    AUTHOR|(CDS)2073202; Andronic, A; Antonczyk, D; Appelshäuser, H; Belaga, V; Bielcikova, J; Braun-Munzinger, P; Busch, O; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Dubitzky, W; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kalisky, M; Kniege, S; Kushpil, V; Maas, A; Marin, A; Milosevic, J; Miskowiec, D; Ortega, R; Panebratsev, Yu A; Petchenova, O; Petracek, V; Ploskon, M; Radomski, S; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schuchmann, S; Schükraft, J; Sedykh, S; Shimansky, S; Soualah, R; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Tsiledakis, G; Wessels, J P; Wienold, T; Wurm, J P; Yurevich, S; Yurevich, V

    2008-01-01

    We present results of a two-pion correlation analysis performed with the Au+Pb collision data collected by the upgraded CERES experiment in the fall of 2000. The analysis was done in bins of the reaction centrality and the pion azimuthal emission angle with respect to the reaction plane. The pion source, deduced from the data, is slightly elongated in the direction perpendicular to the reaction plane, similarly as was observed at the AGS and at RHIC.

  19. Low energy pion--nucleon and pion--deuteron interactions

    International Nuclear Information System (INIS)

    Burman, R.L.

    1975-01-01

    This survey concentrates upon current experiments in the fields of pion-nucleon and pion-deuteron interactions, for low-energy incident pions--below 300 MeV. The discussion is restricted to very recent work. The topics to be covered are: π +- p → π +- p, Elastic Scattering; π +- p → π +- pγ, Bremsstrahlung; π + d → pp, Absorption; π d → π + d, Elastic Scattering; and π + d → π + pn, Breakup. (14 figures) (U.S.)

  20. Coherent optical transition radiation and self-amplified spontaneous emission generated by chicane-compressed electron beams

    Directory of Open Access Journals (Sweden)

    A. H. Lumpkin

    2009-04-01

    Full Text Available Observations of strongly enhanced optical transition radiation (OTR following significant bunch compression of photoinjector beams by a chicane have been reported during the commissioning of the Linac Coherent Light Source accelerator and recently at the Advanced Photon Source (APS linac. These localized transverse spatial features involve signal enhancements of nearly a factor of 10 and 100 in the APS case at the 150-MeV and 375-MeV OTR stations, respectively. They are consistent with a coherent process seeded by noise and may be evidence of a longitudinal space charge microbunching instability which leads to coherent OTR emissions. Additionally, we suggest that localized transverse structure in the previous self-amplified spontaneous emission (SASE free-electron laser (FEL data at APS in the visible regime as reported at FEL02 may be attributed to such beam structure entering the FEL undulators and inducing the SASE startup at those “prebunched” structures. Separate beam structures 120 microns apart in x and 2.9 nm apart in wavelength were reported. The details of these observations and operational parameters will be presented.

  1. Streamer chamber: pion decay

    CERN Multimedia

    1992-01-01

    The real particles produced in the decay of a positive pion can be seen in this image from a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. A magnetic field is added to cause the decay products to follow curved paths so that their charge and momentum can be measured.

  2. Pion radiation therapy

    International Nuclear Information System (INIS)

    Kligerman, M.M.

    1975-01-01

    Results are summarized from studies on the relative biological effects as compared with x or γ radiation and OER of negative pi mesons produced by the Berkeley 184-inch synchrocyclotron or the NIMROD 7-GeV proton synchrocyclotron at the Rutherford High Energy Laboratory in England using cultured animal cells or Vicia faba cells as the test system. Preliminary results are reported from similar radiobiological studies at the Los Alamos Meson Physics Facility. The relative response of human tissues to peak pion irradiation was compared with 140 kV x rays in a single patient with multiple malignant melanoma by observing the acute response of the skin surrounding metastatic modules following exposure to either pions or x radiation. Color photographs of the irradiated areas made at least twice weekly and densitometry measurements and observations by radiation therapists indicated that maximum erythemia occurred during the fifth, sixth, or seventh week after the start of a schedule of fractionated exposure to 15 fractions over 19 elapsed days. X irradiation was delivered at a dose rate of 500 rads/min to modules to deliver 55, 66, or 75 percent of a skin surface dose of 5,200 rads and pion irradiation, at doses numerically 50 percent of the x ray dose, was delivered at a dose rate of 5 to 7 rads/min. Dose response curves were plotted. Results of histological examinations of skin samples taken 24 weeks following irradiation are reported. Results are discussed relative to the destruction of melanoma cells following pion or x ray treatment

  3. Pion Rescattering in Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Paschos, E.A. [Institute for Physics, University of Dortmund, 44221 Dortmund (Germany); Schienbein, I. [Deutsches Elektronen Synchroton (DESY), 22603 Hamburg (Germany); Yu, J.-Y. [Institute for Physics, University of Dortmund, 44221 Dortmund (Germany)

    2005-02-15

    Nuclear corrections are presented for neutrino and electron induced reactions in a pedagogical manner. The formalism is demonstrated with numerical studies and shown to produce substantial corrections in channels where the pions have the same charge with the exchanged current. Two comparisons with available data show consistency of the model. Additional experimental results along these lines will improve the accuracy of the predictions and enhance the discovery potential of experiments.

  4. The effect of an accretion disk on coherent pulsed emission from weakly magnetized neutron stars

    International Nuclear Information System (INIS)

    Asaoka, Ikuko; Hoshi, Reiun.

    1989-01-01

    Using a simple model for hot spots formed on the magnetic polar regions we calculate the X-ray pulse profiles expected from bright low-mass X-ray binaries. We assume that neutron stars in close binary systems are surrounded by accretion disks extending down in the vicinity of their surfaces. Even partial eclipses of a hot spot by the accretion disk change the coherent pulsed fraction and, in some cases, the phase of pulsations by almost 180deg. Coherent pulsations are clearly seen even for sufficiently compact model neutron stars, if the hot spots emit isotropic or fan-beam radiation. In the case of pencil-beam radiation, coherent pulsations are also seen if the cap-opening angle is less than ∼60deg, while the inclination angle is larger than 68deg. Gravitational lensing alone does not smear coherent pulsations in moderately weak magnetized neutron stars in the presence of an absorbing accretion disk. (author)

  5. Pion polarizabilities measurement at COMPASS

    CERN Document Server

    Guskov, Alexey

    2008-01-01

    The electromagnetic structure of pions is probed in $\\pi^{−}+(A,Z) \\rightarrow\\pi^{−}+(A,Z)+\\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric ($\\bar{\\alpha_{\\pi}}$) and the magnetic ($\\bar{\\beta_{\\pi}}$) polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of pointlike pions with the measured cross section. The pion polarizability measurement was performed with a $\\pi^{-}$ beam of 190 GeV. The high beam intensity, the good spectrometer resolution, the high rate capability, the high acceptance and the possibility to use pion and muon beams, unique to the COMPASS experiment, provide the tools to measure precisely the pion polarizabilities in the Primakoff reaction.

  6. Exclusive electroproduction of pion pairs

    International Nuclear Information System (INIS)

    Warkentin, N.; Schaefer, A.; Diehl, M.; Ivanov, D. Yu.

    2007-01-01

    We investigate electroproduction of pion pairs on the nucleon in the framework of QCD factorization for hard exclusive processes. We extend previous analyses by taking the hard-scattering coefficients at next-to-leading order in α s . The dynamics of the produced pion pair is described by two-pion distribution amplitudes, for which we perform a detailed theoretical and phenomenological analysis. In particular, we obtain constraints on these quantities by comparing our results with measurements of angular observables that are sensitive to the interference between two-pion production in the isoscalar and isovector channels. (orig.)

  7. Spectator-velocity pions from heavy ions

    International Nuclear Information System (INIS)

    Rasmussen, J.; Ridout, J.; Murphy, D.; Radi, H.M.A.

    1982-11-01

    The discussion centers on pions in the velocity regions of target and projectile, where strong spectral features appear. The topics covered include stopped-pion studies, and convoy pions in the projectile frame

  8. Pion-pair formation and the pion dispersion relation in a hot pion gas

    Energy Technology Data Exchange (ETDEWEB)

    Chanfay, G. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; Alm, T. [Rostock Univ. (Germany); Schuck, P. [Grenoble-1 Univ., 38 (France). Inst. des Sciences Nucleaires; Welke, G. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy

    1996-09-01

    The possibility of pion-pair formation in a hot pion gas, based on the bosonic gap equation, is pointed out and discussed in detail. The critical temperature for condensation of pion pairs (Evans-Rashind transition) is determined as a function of the pion density. As for fermions, this phase transition is signaled by the appearance of a pole in the two-particle propagator. In Bose systems there exists a second, lower critical temperature, associated with the appearance of the single-particle condensate. Between the two critical temperatures the pion dispersion relation changes from the usual quasiparticle dispersion to a Bogoliubov-like dispersion relation at low momenta. This generalizes the non-relativistic results for an attractive Bose gas by Evans et al. Possible consequences for the inclusive pion spectra measured in heavy-ion collisions at ultra-relativistic energies are discussed. 21 refs.

  9. GYRO-ORBIT SIZE, BRIGHTNESS TEMPERATURE LIMIT, AND IMPLAUSIBILITY OF COHERENT EMISSION BY BUNCHING IN SYNCHROTRON RADIO SOURCES

    International Nuclear Information System (INIS)

    Singal, Ashok K.

    2012-01-01

    We show that an upper limit on the maximum brightness temperature for a self-absorbed incoherent synchrotron radio source is obtained from the size of its gyro orbits, which in turn must lie well within the confines of the total source extent. These temperature limits are obtained without recourse to inverse Compton effects or the condition of equipartition of energy between magnetic fields and relativistic particles. For radio variables, the intra-day variability implies brightness temperatures ∼10 19 K in the comoving rest frame of the source. This, if interpreted purely due to an incoherent synchrotron emission, would imply gyroradii >10 28 cm, the size of the universe, while from the causality arguments the inferred maximum size of the source in such a case is ∼ 15 cm. Such high brightness temperatures are sometimes modeled in the literature as some coherent emission process where bunches of non-thermal particles are somehow formed that radiate in phase. We show that, unlike in the case of curvature radiation models proposed in pulsars, in the synchrotron radiation mechanism the oppositely charged particles would contribute together to the coherent phenomenon without the need to form separate bunches of the opposite charges. At the same time we show that bunches would disperse over dimensions larger than a wavelength in time shorter than the gyro orbital period (∼< 0.1 s). Therefore, a coherent emission by bunches cannot be a plausible explanation of the high brightness temperatures inferred in extragalactic radio sources showing variability over a few hours or longer.

  10. Solar flare pion and neutron production

    International Nuclear Information System (INIS)

    Forrest, D.J.; Vestrand, W.T.

    1992-01-01

    During cycle 21, the Gamma Ray Spectrometer on SMM observed three large flares with clear evidence for pion decay gamma rays and high energy neutrons. Two of these had an extended emission phase. The emission observed in these extended phases were clearly different from those observed in the impulsive phase. Compared to the impulsive phase, the extended phase emissions were strongly deficient in electron bremsstrahlung relative to the nuclear line emission in the 1.0-7.0 MeV band and appeared to have a reduced energetic neutron to pion gamma ray emission in the >10 MeV band. These changes can be produced either by a strong hardening of the accelerated ion spectrum together with a relative decrease in the energetic electron spectrum, or by a pronounced change in the geometry of the particle spectrum downwards towards the photosphere. The authors review the observational evidence in terms of these two possibilities. A dramatic change in the energetic particle geometry appears to offer the simplest explanation. If true these two flares represent the first clear evidence of strong particle geometry effects within individual flares

  11. Pions in nuclei, from virtual-pion exchange to real-pion transfer

    International Nuclear Information System (INIS)

    Yamazaki, Toshimitsu.

    1988-07-01

    Tracing the work of Miyazawa on nuclear magnetic moments, we discuss possible experimental ways to see whether a real pion exists in nuclei or not. While virtual pions are known to play an important role in nuclei, as clarified experimentally from anomalous orbital g factors of nucleons in nuclei, nearly nothing is known for the behavior of real pions in nuclei. We have shown that deeply bound hybrid states of π - are expected to exist in heavy nuclei, which can be populated by ''pion transfer'' reactions. (author)

  12. Many-pion production in π+d reactions at 15 GeV/c

    International Nuclear Information System (INIS)

    Hagopian, V.; Gluch, D.; Hagopian, S.; Horne, C.P.; Jenkins, M.; Lannutti, J.E.; Williams, P.K.; Wind, B.; Cohn, H.O.; Bugg, W.M.; Condo, G.T.; Handler, T.; Hart, E.L.

    1979-01-01

    The average number of charged pions produced in π + d reactions at 15-GeV/c π + momentum is 3.6 +- 0.1 and the average number of π 0 's is 1.9 +- 0.2. The average number of π 0 's produced is essentially independent of the number of charged pions. About 45% of the events have four or more charged pions in the final state. The exclusive final states with four or more charged pions with zero or one π 0 are presented and compared with modified phase-space background computations. Other than the well-known resonances, such as the rho 0 , no new peaks have been observed. Coherently produced multipion systems with up to seven pions are also discussed. Detailed cross-section information for every final state is presented

  13. Pion nucleus optical potential

    International Nuclear Information System (INIS)

    Kam, J. de.

    1981-01-01

    The main goal of the investigations, presented is to establish the contributions to the optical potential, coming from scattering processes which involve 1p-1h nuclear states in the intermediate scattering system. The effects of the Pauli principle corrections and the binding corrections are studied in detail. A phenomenological study of pion absorption effects is also presented. The calculations all concern π- 4 He scattering. The simplicity of the 4 He structure makes the π- 4 He system quite an ideal tool for studying the reaction mechanism. (Auth.)

  14. Subthreshold Production of Neutral Pions in Heavy Ion Collisions

    CERN Multimedia

    2002-01-01

    The pion production below the threshold at 290 MeV/u (corresponding to the minimum beam velocity at which pions can be produced in nucleon-nucleon collisions) is sensitive to coherent effects in the momentum distribution of the nucleons in the internuclear collision region. Such collective or coherent effects would manifest themselves in an enhancement of the observed cross section with respect to a prediction on the basis of model momentum distributions, e.g. from the Fermi gas model. \\\\ \\\\ With neutral pions such experiments can be extended to rather low energies and rather small cross sections (in the sub-@mb range) due to the fact that the @p|0's leave the composite nuclear system undisturbed by the Coulomb forces and that their decay $\\gamma$ rays can be detected with high efficiency also at very low pion momentum. In our experiments using |1|2C~ions of 60, 74 and 84~MeV/u and |1|80 of 84~MeV/u we were able to clearly sep from background from different sources. The large efficiency of the annular lead gl...

  15. Multiple-collision model for pion production in relativistic nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Vary, J.P.

    1978-01-01

    A simple model for pion production in relativistic heavy-ion collisions is developed based on nucleon-nucleon data, nuclear density distribution, and the assumption of straight-line trajectories. Multiplicity distributions for total pion production and for negative-pion production are predicted for 40 Ar incident on a Pb 3 O 4 target at 1.8 GeV/nucleon. Production through intermediate baryon resonances reduces the high-multiplicity region but insufficiently to yield agreement with data. This implies the need for a coherent production mechanism

  16. Investigations in the problem of pion condensation using generator co-ordinate methods

    International Nuclear Information System (INIS)

    Chattopadhyay, P.; Providencia, J. da

    1981-01-01

    Pion condensation in neutron matter has been investigated using the generator coordinate methode and a simple p-wave interaction. The assumption of a condensed mode corresponding to one pion momentum (determined variationally) helps evaluate all the necessary matrix elements exactly. The technique of charge projection from a coherent state of negative pions is discussed, and calculations have been carried out for the cases of average charge conversation, charge projection before variation and for a charge conserving trial function. The ground-state energies and the lowest excitations of the system are obtained from numerical solutions of the Hill-Wheeler equation. (orig.)

  17. Coherent production features in dp interactions at 11.9 GeV/c

    International Nuclear Information System (INIS)

    Braun, H.; Brick, D.; Fridman, A.; Gerber, J.P.; Juillot, P.; Maurer, G.; Alexander, G.; Dagan, S.; Grunhaus, J.; Levy, A.; Lissauer, D.; Oren, Y.

    1975-01-01

    The two pion production in coherent dp reactions is studied. The resonance production as well as the d* effect and the fragmentation processes are discussed. The present reults are compared with available coherent anti-p d data [fr

  18. Coherent electron - hole state and femtosecond cooperative emission in bulk GaAs

    International Nuclear Information System (INIS)

    Vasil'ev, Petr P; Kan, H; Ohta, H; Hiruma, T

    2002-01-01

    The conditions for obtaining a collective coherent electron - hole state in semiconductors are discussed. The results of the experimental study of the regime of cooperative recombination of high-density electrons and holes (more than 3 x 10 18 cm -3 ) in bulk GaAs at room temperature are presented. It is shown that the collective pairing of electrons and holes and their condensation cause the formation of a short-living coherent electron - hole BCS-like state, which exhibits radiative recombination in the form of high-power femtosecond optical pulses. It is experimentally demonstrated that almost all of the electrons and holes available are condensed at the very bottoms of the bands and are at the cooperative state. The average lifetime of this state is measured to be of about 300 fs. The dependences of the order parameter (the energy gap of the spectrum of electrons and holes) and the Fermi energy of the coherent BCS state on the electron - hole concentration are obtained. (special issue devoted to the 80th anniversary of academician n g basov's birth)

  19. Pion polarizabilities measurement at COMPASS

    CERN Document Server

    Guskov, Alexey

    2008-01-01

    The electromagnetic structure of pions is probed in $\\pi^{−} + (A,Z)\\rightarrow\\pi^{−} + (A,Z) +\\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric $(\\bar{\\alpha_{\\pi}})$ and the magnetic $(\\bar{\\beta_{\\pi}})$ polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of pointlike pions with the measured cross section. The pion polarizability measurement was performed with $a \\pi^{−}$ beam of 190 GeV. The high beam intensity, the good spectrometer resolution, the high rate capability, the high acceptance and the possibility to use pion and muon beams, unique to the COMPASS experiment, provide the tools to measure precisely the pion polarizabilities in the Primakoff reaction. The preliminary result for pion polarizabilities under the assumption of $\\bar{\\alpha_{\\pi}} + \\bar{\\beta_{\\pi}} =$ 0 is $\\ba...

  20. Physics of the pion liquid

    International Nuclear Information System (INIS)

    Shuryak, E.V.

    1990-01-01

    Excited hadronic matter in the temperature interval T = 100-200 MeV is not an ideal pion gas, but ratehr a liquid, in which attractive interaction among particles plays an important role. Pion dispersion curve is in this case essentially modified by a kind of collective momentum-dependent potential, which becomes important as the quasipion comes to the boundary of the system. The author shows that these effects can provide an explanation for a number of recent experimental puzzles, in particular, for the observed copious production of soft pions and soft photons in high energy hadronic reactions

  1. Physics of the pion liquid

    International Nuclear Information System (INIS)

    Shuryak, E.V.

    1990-04-01

    Excited hadronic matter in the temperature interval T = 100--200 MeV is not an ideal pion gas, but rather a liquid, in which attractive interaction among particles plays an important role. Pion dispersion curve is in this case essentially modified by a kind of collective momentum-dependent potential, which becomes important as the ''quasipion'' comes to the boundary of the system. We show that effects can provide and explanation for a number of recent experimental puzzles, in particular, for the observed copious production of soft pions and soft photons in high energy hadronic reactions. 31 refs., 13 figs

  2. Pions in the nuclear medium

    International Nuclear Information System (INIS)

    Chanfray, G.

    1996-07-01

    We discuss various aspects of pion physics in the nuclear medium. We first study s-wave pion-nucleus interaction in connection with chiral symmetry restoration and quark condensate in the nuclear medium. We then address the question of p-wave pion-nucleus interaction and collective pionic modes in nuclei and draw the consequences for in medium ππ correlations especially in the scalar-isoscalar channel. We finally discuss the modification of the rho meson mass spectrum at finite density and/or temperature in connection with relativistic heavy ion collisions

  3. Connected and disconnected contractions in pion-pion scattering

    Science.gov (United States)

    Acharya, Neramballi Ripunjay; Guo, Feng-Kun; Meißner, Ulf-G.; Seng, Chien-Yeah

    2017-09-01

    We show that the interplay of chiral effective field theory and lattice QCD can be used in the evaluation of so-called disconnected diagrams, which appear in the study of the isoscalar and isovector channels of pion-pion scattering and have long been a major challenge for the lattice community. By means of partially-quenched chiral perturbation theory, we distinguish and analyze the effects from different types of contraction diagrams to the pion-pion scattering amplitude, including its scattering lengths and the energy-dependence of its imaginary part. Our results may be used to test the current degree of accuracy of lattice calculation in the handling of disconnected diagrams, as well as to set criteria for the future improvement of relevant lattice computational techniques that may play a critical role in the study of other interesting QCD matrix elements.

  4. Backward pion photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Sibirtsev, A; Haidenbauer, J; Huang, F; Krewald, S; Meissner, U -G

    2009-04-01

    We present a systematic analysis of backward pion photoproduction for the reactions $ \\gamma$ p $ \\rightarrow$ $ \\pi^{0}_{}$ p and $ \\gamma$ p $ \\rightarrow$ $ \\pi^{+}_{}$ n . Regge phenomenology is applied at invariant collision energies above 3GeV in order to fix the reaction amplitude. A comparision with older data on $ \\pi^{0}_{}$ - and $ \\pi^{+}_{}$ -photoproduction at $ \\vartheta$ = 180° indicates that the high-energy limit as given by the Regge calculation could be reached possibly at energies of around $ \\sqrt{{s}}$ ≃ 3 GeV. In the energy region of $ \\sqrt{{s}}$ $ \\le$2.5 GeV, covered by the new measurements of $ \\gamma$ p $ \\rightarrow$ $ \\pi^{0}_{}$ p differential cross-sections at large angles at ELSA, JLab, and LEPS, we see no clear signal for a convergence towards the Regge results. The baryon trajectories obtained in our analysis are in good agreement with those given by the spectrum of excited baryons.

  5. Pion form factor

    Energy Technology Data Exchange (ETDEWEB)

    Ryong Ji, C.; Pang, A.; Szczepaniak, A. [North Carolina State Univ., Raleigh, NC (United States)

    1994-04-01

    It is pointed out that the correct criterion to define the legal PQCD contribution to the exclusive processes in the lightcone perturbative expansion should be based on the large off-shellness of the lightcone energy in the intermediate states. In the lightcone perturbative QCD calculation of the pion form factor, the authors find that the legal PQCD contribution defined by the lightcone energy cut saturates in the smaller Q{sup 2} region compared to that defined by the gluon four-momentum square cut. This is due to the contribution by the highly off-energy-shell gluons in the end point regions of the phase space, indicating that the gluon four-momentum-square cut may have cut too much to define the legal PQCD.

  6. The pion's pioneers

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1987-10-15

    In 1946, a band of intrepid physicists took a batch of a new kind of photographic emulsion up the Pic du Midi in the French Pyrenees to expose them to cosmic rays. After analysing the results at Bristol, C. M. G. Lattes, H. Muirhead, G. P. S. Occhialini and C. F. Powell were able to announce early the following year that they had seen the long-awaited pi meson, or pion, postulated by Yukawa in 1935 as the carrier of the strong nuclear force. This landmark discovery quickly revitalized particle physics after all its wartime upheavals. At the end of July, the H. H. Wills Physics Laboratory at Bristol was the scene of an unusual and memorable international conference to mark the 40th anniversary of this discovery.

  7. Improved pion pion scattering amplitude from dispersion relation formalism

    International Nuclear Information System (INIS)

    Cavalcante, I.P.; Coutinho, Y.A.; Borges, J. Sa

    2005-01-01

    Pion-pion scattering amplitude is obtained from Chiral Perturbation Theory at one- and two-loop approximations. Dispersion relation formalism provides a more economic method, which was proved to reproduce the analytical structure of that amplitude at both approximation levels. This work extends the use of the formalism in order to compute further unitarity corrections to partial waves, including the D-wave amplitude. (author)

  8. Electron emission induced by resonant coherent ion-surface interaction at grazing incidence

    International Nuclear Information System (INIS)

    Garcia de Abajo, F.J.; Ponce, V.H.; Echenique, P.M.

    1992-01-01

    A new spectroscopy based on the resonant coherently induced electron loss to the continuum in ion-surface scattering under grazing incidence is proposed. A series of peaks, corresponding to the energy differences determined by the resonant interaction with the rows of atoms in the surface, is predicted to appear in the energy distribution of electrons emitted from electronic states bound to the probe. Calculations for MeV He + ions scattered at a W(001) surface along the left-angle 100 right-angle direction with a glancing angle of 0--2 mrad show a total yield close to 1

  9. Calculation of pion form factor

    International Nuclear Information System (INIS)

    Vahedi, N.; Amirarjomand, S.

    1975-09-01

    The pion form factor is calculated using the structure function Wsub(2), which incorporates kinematical constraints, threshold behaviour and scaling. The Bloom-Gilman sum rule is used and only the two leading Regge trajectories are taken into account

  10. Pion distribution in the nucleon

    International Nuclear Information System (INIS)

    Lee, T.-S.H.

    1989-01-01

    A model is presented for calculating the pion wave function inside the nucleon. By assuming that all pions around a core of the nucleon are in the lowest eigenstate of the system, it is shown that both the bound state and πN scattering amplitude can be consistently described by an exactly soluble model defined in the subspace spanned by the core state and the physical πN state. The parameters of the model are determined by fitting the data of the nucleon mass, πNN coupling constant and low energy πN scattering phase shifts. The model predicts that the probability of finding the pion component inside the nucleon is about 20%. The calculated πNN form factor differs significantly from the conventional monopole form. The dynamical consequences of the differences are demonstrated in a calculation of electromagnetic production of pions from the nucleon and the deuteron. 7 refs., 4 figs., 1 tab

  11. Measurement of Coherent Emission and Linear Polarization of Photons by Electrons in the Strong Fields of Aligned Crystals

    CERN Document Server

    Apyan, A.; Badelek, B.; Ballestrero, S.; Biino, C.; Birol, I.; Cenci, P.; Connell, S.H.; Eichblatt, S.; Fonseca, T.; Freund, A.; Gorini, B.; Groess, R.; Ispirian, K.; Ketel, T.J.; Kononets, Yu.V.; Lopez, A.; Mangiarotti, A.; van Rens, B.; Sellschop, J.P.F.; Shieh, M.; Sona, P.; Strakhovenko, V.; Uggerhoj, E.; Uggerhj, Ulrik Ingerslev; Unel, G.; Velasco, M.; Vilakazi, Z.Z.; Wessely, O.; Kononets, Yu.V.

    2004-01-01

    We present new results regarding the features of high energy photon emission by an electron beam of 178 GeV penetrating a 1.5 cm thick single Si crystal aligned at the Strings-Of-Strings (SOS) orientation. This concerns a special case of coherent bremsstrahlung where the electron interacts with the strong fields of successive atomic strings in a plane and for which the largest enhancement of the highest energy photons is expected. The polarization of the resulting photon beam was measured by the asymmetry of electron-positron pair production in an aligned diamond crystal analyzer. By the selection of a single pair the energy and the polarization of individual photons could be measured in an the environment of multiple photons produced in the radiator crystal. Photons in the high energy region show less than 20% linear polarization at the 90% confidence level.

  12. Efficient trigger signal generation from wasted backward amplified stimulated emission at optical amplifiers for optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Kim Seung Taek

    2015-01-01

    Full Text Available This paper propose an optical structure to generate trigger signals for optical coherence tomography (OCT using backward light which is usually disposed. The backward light is called backward amplified stimulated emission generated from semiconductor optical amplifier (SOA when using swept wavelength tunable laser (SWTL. A circulator is applied to block undesirable lights in the SWTL instead of an isolator in common SWTL. The circulator also diverts backward amplified spontaneous lights, which finally bring out trigger signals for a high speed digitizer. The spectra of the forward lights at SOA and the waveform of the backward lights were measured to check the procedure of the trigger formation in the experiment. The results showed that the trigger signals from the proposed SWTL with the circulator was quite usable in OCT.

  13. Coherent dynamics and terahertz emission in an asymmetric quantum well coupled to broadband infrared pulses

    International Nuclear Information System (INIS)

    Wu, B H; Cao, J C

    2004-01-01

    A selected intersubband transition in the asymmetric quantum well is theoretically proposed by using the superposition of two identical time delayed and phase shifted broadband pulses. Three conduction subbands in the semiconductor quantum well structure are optically coupled with the ultrafast infrared pulses. By adjusting the delay between these two pulses, the carriers at ground level can be selectively pumped to one of the upper levels, while the other upper level remains unoccupied. Thus selective transitions in the three level model can be manipulated by optical interference. At the same time, terahertz radiation will be emitted by coherent controlled charge oscillations. The phase and amplitude of THz radiation is found to be sensitive to the optical interference of the coupling pulses

  14. Coherent terahertz emission from Bi2Sr2CaCu2O8+δ intrinsic Josephson junction stacks

    International Nuclear Information System (INIS)

    Gross, Boris Andre

    2013-01-01

    and heating is not severe, as observed for higher dc input power. For the present thesis, similar structures have been fabricated by H.B. Wang from the National Institute for Material Science in Japan. As preliminary studies suggested, the terahertz emission should also take place for higher input powers, where two electrothermal domains have formed in the mesa, a hot spot and a colder, still superconducting part. This presumption could be confirmed within the present work. Imaging with low-temperature scanning laser microscopy (LTSLM) allowed us to visualize the hot spots in combination with standing wave patterns in the terahertz emission regime. Using various sample geometries, we were able to demonstrate the interaction between the wave patterns and the hot spot, as well as the deliberate manipulation of these processes. In order to determine the linewidth of the radiation, measurements with a superconducting integrated receiver were performed in collaboration with the Kotel'nikov Institute of Radio Engineering and Electronics in Moscow. These measurements revealed a linewidth of about 50 MHz in the presence of a hot spot, which is one order of magnitude smaller as compared to radiation occurring for low bias currents, where no hot spot is present. Investigating the heat balance in one of our mesas from a theoretical perspective, we showed that the formation of electrothermal domains (in particular hot spots) is founded in the strong temperature dependence of the electrical conductivity in c-axis direction of BSCCO. Solving the heat-diffusion equation in three dimensions for the actual sample geometry allowed us to establish realistic temperature profiles of our samples. Most samples that feature coherent terahertz emission were fabricated in a mesa geometry. We showed that samples fabricated with the so-called double-sided fabrication technique emit terahertz radiation in a similar manner.

  15. Microdosimetry of negative pions

    International Nuclear Information System (INIS)

    Amols, H.I.; Dicello, J.F.; Lane, T.F.

    1976-01-01

    The radiation quality of negative and positive pions of initial momentum 168MeV/c has been determined at eight different depths in a liquid phantom. The measurements were made with a 2.5cm diameter spherical proportional counter with Shonka A-150 neutron tissue equivalent plastic walls. The gas pressure in the sensitive volume was chosen to stimulate a diameter of 2μm in unit density material. Dose distributions as a function of lineal energy change slowly in the entrance and plateau regions with a dose mean lineal energy of 6-8keV/μm. Less than 3% of the dose is delivered in excess of 50keV/μm in this region. In the Bragg peak region the distributions change rapidly as a function of depth with the dose mean lineal energy increasing to 38keV/μm at the peak and to 57keV/μm just beyond the peak. On the basis of these microdosimetric data predictions of RBE and OER have been made with the use of both the theory of dual radiation action and also the delta ray theory of cell survival. The former has been used to predict biological response at low doses and the latter at high doses. A comparison is made between the two theories at intermediate doses. The results of these calculations are not inconsistant with recent biological data

  16. Pion production differential cross section of heavy-ion collisions at subthreshold energies

    International Nuclear Information System (INIS)

    Abumurad, K.M.

    1987-01-01

    A revised model for pion production in heavy-ion peripheral collisions at subthreshold energies is presented. The pion-production mechanism investigated here is a two step process involving the formation and subsequent decay of an isobar resonance in the projectile nucleus. The independent-particle shell model with harmonic oscillator states is used to approximate the internal structure of the nucleus. The pion production cross section shows a definite angular distribution characteristic of coherent production. It also gives an indication of the quantum signature of the emitted pions. The results show the disappearance of the quantum signature from the energy spectra because of the inclusion of higher order multipoles. The theory is compared to recent experimental data. The comparison reveals that the general trend is reproduced, which is encouraging

  17. Analysis on heavy quarkonia transitions with pion emission in terms of the QCD multipole expansion and determination of mass spectra of hybrids

    International Nuclear Information System (INIS)

    Ke, Hong-Wei; Tang, Jian; Hao, Xi-Qing; Li, Xue-Qian

    2007-01-01

    One of the most important tasks in high energy physics is the search for the exotic states, such as glueball, hybrid, and multiquark states. The transitions ψ(ns)→ψ(ms)+ππ and Υ(ns)→Υ(ms)+ππ attract great attention because they may reveal characteristics of hybrids. In this work, we analyze those transition modes in terms of the theoretical framework established by Yan and Kuang. It is interesting to notice that the intermediate states between the two gluon emissions are hybrids, therefore by fitting the data, we are able to determine the mass spectra of hybrids. The ground hybrid states are predicted as 4.23 GeV (for charmonium) and 10.79 GeV (for bottonium) which do not correspond to any states measured in recent experiments, thus it may imply that, very possibly, hybrids mix with regular quarkonia to constitute physical states. Comprehensive comparisons of the potentials for hybrids whose parameters are obtained in this scenario with the lattice results are presented

  18. Study on the coherent emission of gluons in QCD jets from electron-positron annihilation

    International Nuclear Information System (INIS)

    Kreutzmann, H.

    1990-11-01

    The inclusive momentum distribution of charged particles is studied with the OPAL detector at LEP in multihadronic events produced in e + e - -annihilations at E cm ≅ M(Z 0 ). Agreement is found with analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from c.m. energies between 14 GeV and 91 GeV, the dependence of the inclusive momentum distribution on the centre of momentum energy E cm is investigated. The analytic predictions derived from perturbative energy E cm ≅ M(Z 0 ) and its change with E cm are also described by QCD shower Monte Carlo programs which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and the momentum spectra. A detailed simulation of the OPAL Jet Chamber and a reconstruction program for jet chamber tracks were developed and applied in this analysis. The essential features of both programs are presented. (orig.) [de

  19. Various models for pion probability distributions from heavy-ion collisions

    International Nuclear Information System (INIS)

    Mekjian, A.Z.; Mekjian, A.Z.; Schlei, B.R.; Strottman, D.; Schlei, B.R.

    1998-01-01

    Various models for pion multiplicity distributions produced in relativistic heavy ion collisions are discussed. The models include a relativistic hydrodynamic model, a thermodynamic description, an emitting source pion laser model, and a description which generates a negative binomial description. The approach developed can be used to discuss other cases which will be mentioned. The pion probability distributions for these various cases are compared. Comparison of the pion laser model and Bose-Einstein condensation in a laser trap and with the thermal model are made. The thermal model and hydrodynamic model are also used to illustrate why the number of pions never diverges and why the Bose-Einstein correction effects are relatively small. The pion emission strength η of a Poisson emitter and a critical density η c are connected in a thermal model by η/n c =e -m/T <1, and this fact reduces any Bose-Einstein correction effects in the number and number fluctuation of pions. Fluctuations can be much larger than Poisson in the pion laser model and for a negative binomial description. The clan representation of the negative binomial distribution due to Van Hove and Giovannini is discussed using the present description. Applications to CERN/NA44 and CERN/NA49 data are discussed in terms of the relativistic hydrodynamic model. copyright 1998 The American Physical Society

  20. Pions to Quarks

    Science.gov (United States)

    Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian

    2009-01-01

    Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the

  1. Radio emission from quasars and BL Lac objects by coherent plasma oscillation and stimulated Compton scattering

    International Nuclear Information System (INIS)

    Colgate, S.A.; Petschek, A.G.

    1978-01-01

    The full radiation spectrum of quasars and BL Lac objects is interpreted as due to a dependent combination of a soft plasma oscillation source at 2ν/sub P/ and bremsstrahlung. Previous work of the plasma oscillation radiation is extended into the radio part of the spectrum and it is shown how the high brightness temperature observations of BL Lac objects [kT/sub b/ (100 MHz) approximate = 3 x 10 5 mc 2 ] are a reasonable consequence of a lower external plasma density and ejection as required for the observed lack of emission lines. Two extreme cases are considered, the one where the plasma oscillations are suddenly extinguished and only stimulated Compton scattering remains and a second case of a constant source of plasma oscillations but a graded surface density. The first case gives 1/100 of the required brightness temperature and the second gives 100 times too large a brightness temperature and also a x 10 too large a radius. It is believed reasonable to invoke a combination of both processes to explain the observed radio spectrum. This model circumvents the self-Compton x-ray flux difficulty of incoherent synchrotron emission

  2. Quark bag coupling to finite size pions

    International Nuclear Information System (INIS)

    De Kam, J.; Pirner, H.J.

    1982-01-01

    A standard approximation in theories of quark bags coupled to a pion field is to treat the pion as an elementary field ignoring its substructure and finite size. A difficulty associated with these treatments in the lack of stability of the quark bag due to the rapid increase of the pion pressure on the bad as the bag size diminishes. We investigate the effects of the finite size of the qanti q pion on the pion quark bag coupling by means of a simple nonlocal pion quark interaction. With this amendment the pion pressure on the bag vanishes if the bag size goes to zero. No stability problems are encountered in this description. Furthermore, for extended pions, no longer a maximum is set to the bag parameter B. Therefore 'little bag' solutions may be found provided that B is large enough. We also discuss the possibility of a second minimum in the bag energy function. (orig.)

  3. Experiments on the nuclear interactions of pions and electrons

    International Nuclear Information System (INIS)

    Minehart, R.C.; Ziock, K.O.H.

    1990-06-01

    This paper discusses: π + + d → 2p; Pion Absorption in 3 He; Pion Absorption in 4 He; Evidence for narrow structure in the analyzing power of the 3 He (rvec p, d)X reaction; Coherent η-Meson Production in the Reaction π- + 3 He → η + t; Search for heavy neutrinos; The search for fractionally charged particles; Search for the rare decay, μ + → e + + γ; A Precise Measurement of the π + → π 0 e + ν Decay Rate; Transverse and Longitudinal Response Functions for Several Nuclei near Q 2 = 1 (GeV/c) 2 ; The Q 2 -dependence of the 4 He (e, e'p) coincidence cross section at the quasielastic peak; The Response Function R LT in the reaction 16 O(e, e' p); and Absorption of anti-protons in heavy nuclei

  4. Pion structure from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Javadi Motaghi, Narjes

    2015-05-12

    In this thesis we use lattice QCD to compute the second Mellin moments of pion generalized parton distributions and pion electromagnetic form factors. For our calculations we are able to analyze a large set of gauge configurations with 2 dynamical flavours using non-perturbatively the improved Wilson-Sheikholeslami-Wohlert fermionic action pion masses ranging down to 151 MeV. By employing improved smearing we were able to suppress excited state contamination. However, our data in the physical quark mass limit show that some excited state contamination remains. We show the non-zero sink momentum is optimal for the computation of the electromagnetic form factors and generalized form factors at finite momenta.

  5. Pion condensation in symmetric nuclear matter

    International Nuclear Information System (INIS)

    Kabir, K.; Saha, S.; Nath, L.M.

    1987-09-01

    Using a model which is based essentially on the chiral SU(2)xSU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenon is expected to be seen in the pion-nucleus interaction. (author). 20 refs

  6. Pion condensation in symmetric nuclear matter

    Science.gov (United States)

    Kabir, K.; Saha, S.; Nath, L. M.

    1988-01-01

    Using a model which is based essentially on the chiral SU(2)×SU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenom is expected to be seen in the pion-nucleus interaction.

  7. Scrutinizing the pion condensed phase

    Energy Technology Data Exchange (ETDEWEB)

    Carignano, Stefano; Mammarella, Andrea; Mannarelli, Massimo [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lepori, Luca [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Universita dell' Aquila, Dipartimento di Scienze Fisiche e Chimiche, Coppito-L' Aquila (Italy); Pagliaroli, Giulia [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Gran Sasso Science Institute, L' Aquila (Italy)

    2017-02-15

    When the isospin chemical potential exceeds the pion mass, charged pions condense in the zero-momentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The low-density expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the ''radial'' fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition. (orig.)

  8. Neutral pion production in heavy ion collisions at SIS-energies

    International Nuclear Information System (INIS)

    Sumbera, M.; Loehner, H.; Raschke, A.E.; Venema, L.B.; Wilschut, H.W.

    1993-01-01

    The production of π 0 mesons has been studied in the reactions 40 Ar+Ca and 197 Au+Au at 1.0 GeV/u. While the pion transverse momentum spectrum from the reaction Ar+Ca is consistent with a simple thermal exponential slope a second component is seen for the system Au+Au. Both neutral pions, neutrons and charged particles exhibit an anisotropy in the reaction plane azimuth. At midrapidity the emission of pions perpendicular to the reaction plane increases with their energy. (orig.)

  9. Two pion correlation from SPACER

    International Nuclear Information System (INIS)

    Csoergoe, T.; Zimanyi, J.; Pratt, S.

    1989-12-01

    The correlation function for neutral and negative pions produced in ultrarelativistic heavy ion collisions was calculated without free parameters based on a space-time version of the LUND model, called SPACER: Simulation of Phase space distribution of Atomic nuclear Collisions in Energetic Reactions. This method includes the effect of Bose correlations for the emitted pion pair. Effects arising from correlations between space-time and momentum space distributions are investigated. The results are compared to the data of two different experiments. The role and interpretation of the chaocity parameter are discussed. (D.G.) 14 refs.; 4 figs

  10. Radiative pion-proton scattering

    International Nuclear Information System (INIS)

    Ho-Kim, Q.; Lavine, J.P.

    1977-01-01

    The results are presented of a non-relativistic calculation of the π +- proton bremsstrahlung cross section at the pion kinetic energy of 298 MeV for backward photon angles. The pion-nucleon interaction is given by models that are based on the p-wave Chew-Low theory. An interaction current is included in an attempt to make the overall bremsstrahlung amplitude gauge-invariant. The predicted cross sections show little of the expected resonance, and are in fair agreement with the data. The authors have also calculated the cross sections at other kinetic energies, and have studied effects of the off-mass-shell electromagnetic vertex. (Auth.)

  11. Crystal physics with positive pions

    International Nuclear Information System (INIS)

    Flik, G.

    1983-01-01

    The π + /μ + lattice channeling is a new method of investigation in solid state physics. In the present thesis axial and planar channeling effects could be observed for the first time in monocrystalline Tantalum for 4, 12 MeV Muons generated by the decay of implanted positive pions. It is found that pions for T + /μ + channeling is investigated in Germanium for low temperatures. For T > 80 K tetrahedral sites are found, but for T < 80 K hexaedral sites or sites in the middle of the Ge-Ge bond are preferred. (BHO)

  12. Mechanism of pion absorption in complex nuclei

    International Nuclear Information System (INIS)

    Doss, K.G.N.; Wharton, W.R.

    Basic geometrical arguments are used to analyze the A dependence of the total pion absorption cross section, the effective number of nucleons sharing the pion momentum and energy, and the proton yields from π + - and π - -induced reactions. The results are consistent with the pions penetrating some distance through the nuclear volume and annihilating on a pair of nucleons. 3 figures

  13. Pion inelastic scattering and the pion-nucleus effective interaction

    International Nuclear Information System (INIS)

    Carr, J.A.

    1983-01-01

    This work examines pion inelastic scattering with the primary purpose of gaining a better understanding of the properties of the pion-nucleus interaction. The main conclusion of the work is that an effective interaction which incorporates the most obvious theoretical corrections to the impulse approximation does a good job of explaining pion elastic and inelastic scattering from zero to 200 MeV without significant adjustments to the strength parameters of the force. Watson's multiple scattering theory is used to develop a theoretical interaction starting from the free pion-nucleon interaction. Elastic scattering was used to calibrate the isoscalar central interaction. It was found that the impulse approximation did poorly at low energy, while the multiple scattering corrections gave good agreement with all of the data after a few minor adjustments in the force. The distorted wave approximation for the inelastic transition matrix elements are evaluated for both natural and unnatural parity excitations. The isoscalar natural parity transitions are used to test the reaction theory, and it is found that the effective interaction calibrated by elastic scattering produces good agreement with the inelastic data. Calculations are also shown for other inelastic and charge exchange reactions. It appears that the isovector central interaction is reasonable, but the importance of medium corrections cannot be determined. The unnatural parity transitions are also reasonably described by the theoretical estimate of the spin-orbit interaction, but not enough systematic data exists to reach a firm conclusion

  14. Real-pion states formed by virtual-pion beam

    International Nuclear Information System (INIS)

    Yamazaki, Toshimitsu.

    1990-04-01

    Deeply bound pionic states are discussed from various points of view; highly excited nuclear states as a cluster family of pionic bound states, Σ atom/Σ hypernuclei, halo-like density distributions, virtual pion beam to produce pionic states, etc. (author)

  15. A Study of Charged Current Single Charged Pion Productions on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Hiraide, Katsuki [Kyoto Univ. (Japan)

    2009-01-01

    Understanding single charged pion production via neutrino-nucleus charged current interaction in the neutrino energy region of a few GeV is essential for future neutrino oscillation experiments since this process is a dominant background for vμ → vx oscillation measurements. There are two contributions to this process: single pion production via baryonic resonance (vμN → μ-+) and coherent pion production interacting with the entire nucleus (vμA → μ-+), where N is nucleon in the nucleus and A is the nucleus. The purpose of the study presented in this thesis is a precise measurement of charged current single charged pion productions, resonant and coherent pion productions, with a good final state separation in the neutrino energy region of a few GeV. In this thesis, we focus on the study of charged current coherent pion production from muon neutrinos scattering on carbon, vμ 12C → μ-12+, in the SciBooNE experiment. This is motivated by the fact that without measuring this component first, the precise determination of resonant pion production cross section can not be achieved since the contribution of coherent pion production in the region of small muon scattering angle is not small. Furthermore, the coherent process is particularly interesting because it is deeply rooted in fundamental physics via Adler's partially conserved axial-vector current theorem. We took data from June 2007 until August 2008, in both the neutrino and antineutrino beam. In total, 2.52 x 1020 protons on target were collected. We have performed a search for charged current coherent pion production by using SciBooNE's full neutrino data set, corresponding to 0.99 x 1020 protons on target. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio

  16. Pion production in nucleus--nucleus collisions

    International Nuclear Information System (INIS)

    Schroeder, L.S.

    1975-06-01

    Current work on pion production in high-energy nucleus-nucleus collisions is reviewed. The majority of existing data are of the inclusive variety in which a single final state pion is detected. Experimental data are compared and their possible contributions to obtaining new information on nuclear structure is discussed. Various models which attempt to explain the observed single-inclusive-pion spectra either on the basis of a nucleon-nucleus interaction in which Fermi motion is included or on some type of cooperative model are examined. Other areas of interest involving pion production include tests of charge symmetry and pion multiplicities. (9 figures, 1 table) (U.S.)

  17. Measurement of the pion form factor

    International Nuclear Information System (INIS)

    Dally, E.; Hauptman, J.; May, C.

    1977-01-01

    The pion form factor has been measured in the momentum transfer range of 0.03( 2 by scattering pions from atomic electrons in a liquid hydrogen target. The pion form factor is defined to be the elastic scattering cross section divided by that predicted for a point pion. The experiment has been performed in a 100 GeV/c negative pion beam incident on a 50 cm liquid hydrogen target at Fermi laboratory. The corrected form factor equals 0.33+-0.06 f 2 . Vector dominance predicts 0.40 f 2

  18. Pion condensation in symmetric nuclear matter

    International Nuclear Information System (INIS)

    Shamsunnahar, T.; Saha, S.; Kabir, K.; Nath, L.M.

    1991-01-01

    We have investigated the possibility of pion condensation in symmetric nuclear matter using a model of pion-nucleon interaction based essentially on chiral SU(2) x SU(2) symmetry. We have found that pion condensation is not possible for any finite value of the density. Consequently, no critical opalescence phenomenon is likely to be seen in pion-nucleus scattering nor is it likely to be possible to explain the EMC effect in terms of an increased number of pions in the nucleus. (author)

  19. Rare pion and kaon decays

    International Nuclear Information System (INIS)

    Bryman, D.

    1983-09-01

    Some rare pion and kaon decays, which provide clues to the generation puzzle, are discussed. The π→ eν/π→μ/ν branching ratio test of universality and the status of searches for K + → π + rho anti rho are reviewed

  20. The pion-nucleus interaction

    International Nuclear Information System (INIS)

    Afnan, I.R.

    1977-04-01

    The latest developments in the construction of pion-nucleus optical potential are presented and a comparison with the latest data on π+ 12 C is made. The suggested mechanisms for the (p,π) reaction are discussed with a comparison of the theoretical results with experiment. (Author)

  1. Real and virtual pions in nuclei

    International Nuclear Information System (INIS)

    Giraud, N.

    1984-02-01

    The thesis first part is concerned with physical pion interaction with deuton, studied in a three-body problem frame. The elastic cross-section in the energy range near the resonance (3-3), has been deduced taking in account the pion virtual absorption. The second part is concerned with virtual pion in nuclei. In particular the virtual pion cloud around the nucleus has been studied and the effective constant coupling pion-nucleus has been deduced. This one is strongly reduced by polorazation effects of the nuclear medium (essentially by virtual excitation of the Δ isobar), in relation to its value for free nucleon collection. In the frame of the same polarization model, the pion field inside the nucleus has been studied also. This field is lowered for small momentum transfer. It is increased for large momentum transfer. This last phenomenon corresponds to critical opalescence related to phase transition of pion condensation [fr

  2. Intermediate-energy nuclear photoabsorption and the pion optical potential

    International Nuclear Information System (INIS)

    Christillin, P.

    1984-01-01

    Nuclear photoabsorption around the pion threshold is schematised as photoproduction of a pion which undergoes final-stae interaction with the nucleus, accounted for by the pion optical potential. It is shown that real pion photoproduction and exchange effects are naturally described by the same mechanism with a non-static pion. The complementarity of photoabsorption to pion physics and its usefulness in gaining new information about pion-nucleus dynamics are stressed. (author)

  3. Determination of the pion-nucleon coupling constant and scattering lengths

    CERN Document Server

    Ericson, Torleif Eric Oskar; Thomas, A W

    2002-01-01

    We critically evaluate the isovector GMO sum rule for forward pion-nucleon scattering using the recent precision measurements of negatively charged pion-proton and pion-deuteron scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data a pseudoscalar coupling constant of 14.17+-0.05(statistical)+-0.19(systematic) or a pseudovector one of 0.0786(11). This value is intermediate between that of indirect methods and the direct determination from backward neutron-proton differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the negatively charged pion-proton and pion-neutron scattering lengths with high precision. The symmetric sum gives 0.0017+-0.0002(statistical)+-0.0008 (systematic) and the antisymmetric one 0.0900+-0.0003(statistical)+-0.0013(systematic), both in units of inverse charged pi...

  4. Two-pion correlations in heavy ion collisions

    International Nuclear Information System (INIS)

    Zajc, W.A.

    1982-08-01

    An application of intensity interferometry to relativistic heavy ion collisions is reported. Specifically, the correlation between two like-charged pions is used to study the reactions Ar+KCl→2π/sup +-/+X and Ne+NaF→2π - +X. Source sizes are obtained that are consistent with a simple geometric interpretation. Lifetimes are less well determined but are indicative of a faster pion production process than predicted by Monte Carlo cascade calculations. There appears to be a substantial coherent component of the pion source, although measurement is complicated by the presence of final state interactions. Additionally, the generation of spectra of uncorrelated events is discussed. In particular, the influence of the correlation function on the background spectrum is analyzed, and a prescription for removal of this influence is given. A formulation to describe the statistical errors in the background is also presented. Finally, drawing from the available literature, a self-contained introduction to Bose-Einstein correlations and the Hanbury-Brown - Twiss effect is provided, with an emphasis on points of contact between classical and quantum mechanical descriptions

  5. Measuring pion beta decay with high-energy pion beams

    International Nuclear Information System (INIS)

    McFarlane, W.K.; Hoffman, C.M.

    1993-01-01

    Improved measurements of the pion beta decay rate are possible with an intense high-energy pion beam. The rate for the decay π + → π 0 e + vε is predicted by the Standard Model (SM) to be R(π + → π 0 e + vε) = 0.3999±0.0005 s -1 . The best experimental number, obtained using in-flight decays, is R(π + → π 0 e + vε) = 0.394 ± 0.015 s -1 . A precise measurement would test the SM by testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix for which one analysis of the nuclear beta decay data has shown a 0.4% discrepancy. Several nuclear correction factors, needed for nuclear decay, are not present for pion beta decay, so that an experiment at the 0.2% level would be a significant one. Detailed study of possible designs will be needed, as well as extensive testing of components. The reduction of systematic errors to the 0.1% level can only be done over a period of years with a highly stable apparatus and beam. At a minimum, three years of occupancy of a beam line, with 800 hours per year, would be required

  6. DWPI: a computer program to calculate the inelastic scattering of pions from nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Eisenstein, R A; Miller, G A [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics

    1976-02-01

    Angular distributions for the inelastic scattering of pions are generated using the distorted wave impulse approximation (DWIA). The cross section for a given transition is calculated by summing a partial wave expansion. The T-matrix elements are calculated using distorted pion waves from the program PIRK, and therefore include elastic scattering to all orders. The excitation is treated in first order only. Several optical potentials and nuclear densities are available in the program. The transition form factor may be uncoupled from the ground-state density. Coulomb excitation, which interferes coherently with the strong interaction, is a program option.

  7. ABC's of pion charge exchange

    International Nuclear Information System (INIS)

    Gibbs, W.R.; Kaufmann, W.B.; Siegel, P.B.

    1985-01-01

    Calculations of pion single charge exchange using the PWIA and DWIA are presented. Emphasis is given to the effects of absorbtion and blocking. A microscopic calculation of the 0 0 excitation and low energy angular distribution is in excellent agreement with the data. A fixed nucleon multiple scattering calculation of the pion double charge exchange reaction is presented. Various valence neutron wave functions are used, and the contributions of different spatial orientations of the last two neutrons to the reaction are examined. The DCX cross section is found to be very sensitive to the inclusion of correlations in the two-neutron wave function. Satisfactory agreement with DCX data on 14 C can be obtained using a nucleonic picture of the nucleus

  8. Two- and three-pion quantum statistics correlations in Pb-Pb collisions at s N N = 2.76 TeV at the CERN Large Hadron Collider

    NARCIS (Netherlands)

    Abelev, B.; Adam, J.; Adamová, D.; Aggarwal, M. M.; Rinella, G. Aglieri; Agnello, M.; Agocs, A. G.; Agostinelli, A.; Agrawal, N.; Ahammed, Z.; Ahmad, N.; Masoodi, A. Ahmad; Ahmed, I.; Ahn, S. U.; Ahn, S. A.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altini, V.; Altinpinar, S.; Altsybeev, I.; Prado, C. Alves Garcia; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arbor, N.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bairathi, V.; Bala, R.; Baldisseri, A.; Pedrosa, F. Baltasar Dos Santos; Bán, J.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Baumann, C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Berger, M. E.; Bergognon, A. A E; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Boehmer, F. V.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bornschein, J.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Bruna, E.; Bruno, G. 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K.; Palmeri, A.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Park, W. J.; Passfeld, A.; Patalakha, D. I.; Paticchio, V.; Paul, B.; Pawlak, T.; Peitzmann, T.; Da Costa, H. Pereira; Filho, E. Pereira De Oliveira; Peresunko, D.; Lara, C. E Pérez; Peryt, W.; Pesci, A.; Pestov, Y.; Petráček, V.; Petran, M.; Petris, M.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Planinic, M.; Płoskoń, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L M; Poghosyan, M. G.; Pohjoisaho, E. H O; Polichtchouk, B.; Poljak, N.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, V.; Potukuchi, B.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Rauf, A. W.; Razazi, V.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. 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P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; Von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wagner, V.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C S; Windelband, B.; Winn, M.; Xiang, C.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yang, S.; Yano, S.; Yasnopolskiy, S.; Yi, J.; Yin, Z.; Yoo, I. K.; Yushmanov, I.; Zaccolo, V.; Zach, C.; Zaman, A.; Zampolli, C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, F.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhou, D.; Zhou, F.; Zhou, Y.; Zhu, H.; Zhu, J.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zoccarato, Y.; Zynovyev, M.; Zyzak, M.

    2014-01-01

    Correlations induced by quantum statistics are sensitive to the spatiotemporal extent as well as dynamics of particle-emitting sources in heavy-ion collisions. In addition, such correlations can be used to search for the presence of a coherent component of pion production. Two- and three-pion

  9. Study of the Two Pion Photoproduction on Deuterium

    Science.gov (United States)

    Gauss, Lewis P. Graham, Jr.

    Spectrometer (CLAS), the hadronic products are detected in coincidence with the incident scattered photon on a deuterium target. This makes it possible to measure the single differential cross sections and the decay angular distributions for the production of two pion final states. The measured cross sections will contribute significantly to a better understanding of the coupling strengths that govern the baryonic and mesonic resonances which will push the knowledge of the strong interaction to a next level. We use CLAS to study the two pion channel from the eg3 data set, for resonance production, specifically investigating the exclusive reaction of γd → pπ+π n, and comparing the relevant cross sections to already existing data sets. The eg3 data set provided an excellent data set for investigating photo-induced baryonic and mesonic resonances. It contains a large photon tagging range from 1.1 to 5.5 GeV in the study of photo-coupling strengths, as well as an available two pion reaction channel for resonant decay study. These measurements provide unique and coherent results from tagged photons over a broad range of energy, and represent the only two pion production data above 5 GeV at this present time. We found that the data produced good comparable single-differentials cross sections to other existing CLAS (gll dataset) two pion differential cross sections, and an excellent comparable total cross section to published (ELSA and ABBHHM) two pion total cross sections.

  10. Study of the Two-pion Photoproduction on the Deuteron

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Lewis P. [Univ. of South Carolina, Columbia, SC (United States)

    2012-12-01

    Acceptance Spectrometer (CLAS), the hadronic products are detected in coincidence with the incident scattered photon on a deuterium target. This makes it possible to measure the single differential cross sections and the decay angular distributions for the production of two pion final states. The measured cross sections will contribute significantly to a better understanding of the coupling strengths that govern the baryonic and mesonic resonances which will push the knowledge of the strong interaction to a next level. We use CLAS to study the two pion channel from the eg3 data set, for resonance production, specifically investigating the exclusive reaction of yd --> p pi^+pi^?n, and comparing the relevant cross sections to already existing data sets. The eg3 data set provided an excellent data set for investigating photo-induced baryonic and mesonic resonances. It contains a large photon tagging range from 1.1 to 5.5 GeV in the study of photo-coupling strengths, as well as an available two pion reaction channel for resonant decay study. These measurements provide unique and coherent results from tagged photons over a broad range of energy, and represent the only two pion production data above 5 GeV at this present time. We found that the data produced good comparable single-differentials cross sections to other existing CLAS (gll dataset) two pion differential cross sections, and an excellent comparable total cross section to published (ELSA and ABBHHM) two pion total cross sections.

  11. Pion scattering and nuclear dynamics

    International Nuclear Information System (INIS)

    Johnson, M.B.

    1988-01-01

    A phenomenological optical-model analysis of pion elastic scattering and single- and double-charge-exchange scattering to isobaric-analog states is reviewed. Interpretation of the optical-model parameters is briefly discussed, and several applications and extensions are considered. The applications include the study of various nuclear properties, including neutron deformation and surface-fluctuation contributions to the density. One promising extension for the near future would be to develop a microscopic approach based on powerful momentum-space methods brought to existence over the last decade. In this, the lowest-order optical potential as well as specific higher-order pieces would be worked out in terms of microscopic pion-nucleon and delta-nucleon interactions that can be determined within modern meson-theoretical frameworks. A second extension, of a more phenomenological nature, would use coupled-channel methods and shell-model wave functions to study dynamical nuclear correlations in pion double charge exchange. 35 refs., 11 figs., 1 tab

  12. Radiation quality of beams of negative pions

    International Nuclear Information System (INIS)

    Dicello, J.F.; Brenner, D.J.

    1981-01-01

    As a negative pion stops in tissue, it attaches itself to an adjacent atom to form a mesonic atom. Subsequently, the wave function of the pion interacts with that of the nucleus and the pion is absorbed. Because the energy associated with the rest mass of the pion is greater than the separation energy of the nuclear particles, the nucleus disintegrates (pion star). In tissue, approximately 40 MeV goes into overcoming the binding energies; 20 MeV goes into kinetic energy of charged particles; 80 MeV goes into kinetic energy of neutrons. In cases where biological studies are performed with beams of negative pions, as much as 20% of the total absorbed dose in the treatment volume and about 50% of the high-LET dose (> 100 keV/μm) can result from neutrons. The degree of biological response and the variation of that response throughout the treatment volume can be altered by the neutron dose

  13. Pion-nuclear many body problems

    International Nuclear Information System (INIS)

    Weise, W.

    1981-01-01

    This chapter examines pion-nucleus scattering data produced at the meson factories in order to gain information about the ''optical'' branches of the pion-nuclear excitation spectrum. Discusses basic meson-baryon effective Lagrangians and elementary processes; pion-baryon vertex form factors; the spin-isospin dependent baryon-baryon interaction; pions in nuclear matter; nuclear spin-isospin correlations; the baryon-hole model; photon-induced excitation of baryon-hole states; high momentum transfer properties of pion-like nuclear states; a response function for pionic low-frequency modes in finite nuclei; and applications. Finds that there is no clear evidence for pionic critical opalescence, as in agreement with the expectation that the minimal density for the appearance of a pion condensate is certainly not lower than two or three times nuclear matter density

  14. The pion mass: Looking for its origins

    International Nuclear Information System (INIS)

    Peccei, R.D.

    1985-10-01

    After explaining why pions are special excitations in QCD, I discuss how the pion mass reflects directly the dynamical scale of the strong interactions (Λsub(QCD)) and the scale of breaking of the weak interactions (Λsub(F)). To actually calculate the pion mass, however, requires understanding the origin of the quark masses and so I compare and contrast approaches to this latter problem, based on composite models and on superstrings. (orig.)

  15. Fast pion production in exclusive neutrino processes

    International Nuclear Information System (INIS)

    Gershtein, S.S.; Komachenko, Yu.Ya.; Khlopov, M.Yu.

    1980-01-01

    Single pion production in exclusive neutrino reactions with small momentum transfer to nucleon, induced by neutrino scattering on virtual mesons (reggeons), is considered. The estimation of the contributions to process νA → μπA where A is a nucleon or the target nucleus made by various virtual mesons is presented. In the experimental investigation of such processes the contributions of different mesons may be singled out, thus providing information on the weak; meson-pion (reggeon-pion) transitions

  16. The pion form factor from first principles

    International Nuclear Information System (INIS)

    Heide, J. van der

    2004-01-01

    We calculate the electromagnetic form factor of the pion in quenched lattice QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is used together with the O(a) improved current. We calculate form factor for pion masses down to mπ = 380 MeV. We compare the mean square radius for the pion extracted from our form factors to the value obtained from the 'Bethe Salpeter amplitude'. Using (quenched) chiral perturbation theory, we extrapolate our results towards the physical pion mass

  17. Abnormal anti-Stokes Raman emission as a coherent anti-Stokes Raman scattering-like process in disordered media

    International Nuclear Information System (INIS)

    Baltog, Ioan; Baibarac, Mihaela; Smaranda, Ion; Lefrant, Serge

    2011-01-01

    In this paper, we demonstrate that, by continuous single beam excitation, one can generate an abnormal anti-Stokes Raman emission (AASRE) whose properties are similar to a coherent anti-Stokes Raman scattering (CARS). The effect has been observed in materials which possess intrinsically nonlinear properties (LiNbO 3 and CdS), which have the electric susceptibility of third order different from zero, χ (3) ≠ 0, as well as in materials that become nonlinear under resonant optical excitation. In the latter case, we used poly-3,4-ethylendioxythiophene (PEDOT) in its undoped state deposited electrochemically on Au support. Raman studies corroborated with images of optical microscopy demonstrate that the production of AASRE is conditioned by the existence of a particular morphology of the sample able to ensure efficient transport of the light inside the sample through a multiple light scattering mechanism. In this context, it was found that LiNbO 3 and CdS in powder form as well as the PEDOT films layered on a rough Au substrate are suitable morphological forms. We explain AASRE as resulting from a wave-mixing mechanism of the incident laser light ω l with a Stokes-shifted Raman light ω S produced by a spontaneous Raman light scattering process, both strongly scattered inside the sample. As a CARS process, AASRE is conditioned by the achievement of phase-matching requirements, which makes the difference between the wave vectors of mixing light close to zero, Δk =/2k l - k S - k CARS /∼ 0. In condensed media, the small dispersion of the refractive index makes Δk ∼ 0 so that the formation of a favourable phase-matching geometry may be accomplished even at a crossing angle θ of travelling scattered light ω l and ω S . For tightly focused beams, the requirement of phase matching relaxes; it is no longer sensitive to the Raman shift, so that a wide intense anti-Stokes Raman spectrum is observed at an angle larger than the Stokes Raman spectrum.

  18. Pion electromagnetic polarizabilities and quarks

    International Nuclear Information System (INIS)

    Llanta, E.; Tarrach, R.

    1980-01-01

    The electric and magnetic polarizabilities of the neutral and charged pion are calculated in a coloured quark field theory at the one-loop level. The theory has as free parameter the quark mass but our results do not depend on it. We have found that the electric polarizabilities are αsub(π+-) = -0.04 α/m 3 sub(π), αsub(π 0 ) = -0.4 α/m 3 sub(π). These values are compared with calculations in other models and some comments are made about the polarizability sum rules. (orig.)

  19. Pion production experiments at IUCF

    Science.gov (United States)

    Daehnick, W. W.

    2001-12-01

    Pion production in pp collisions is of special interest near threshold where very few partial waves contribute and where calculations should be manageable and results more conclusive. The first explicit calculations for pp → ppπ0 and pp → pnπ+ cross sections near threshold were made by Koltun and Reitan in 1966 and by Schillaci, Silbar and Young in 1969. They remained unchallenged and untested until cross sections very close to threshold could finally be measured1,2. The realization that the pioneering calculations missed the true cross sections by a wide margin has spurred much new theoretical research.3,4,5 ...

  20. The future IKO-PION-MUON-facility

    International Nuclear Information System (INIS)

    Goudsmit, P.F.A.; Arnold, H.; Dantzig, R. van; Konijn, J.

    1975-09-01

    Information is given on the pion and muon physics facility planned at the Institute for Nuclear Physics Research (IKO) with special notice of the fluxes of pions and muons expected at this facility, as well as on the structure of these secondary beams

  1. Strangeness production with protons and pions

    International Nuclear Information System (INIS)

    Dover, C.B.

    1993-01-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei

  2. Pion double charge exchange and nuclear structure

    International Nuclear Information System (INIS)

    Ginocchio, J.N.

    1987-01-01

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

  3. Pion-Kaon correlations in central Au+Au collisions at square root [sNN] = 130 GeV.

    Science.gov (United States)

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gutierrez, T D; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-12-31

    Pion-kaon correlation functions are constructed from central Au+Au STAR data taken at sqrt[s(NN)]=130 GeV by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e., transverse flow, lead to a space-time emission asymmetry of pions and kaons that is consistent with the data. This result provides new independent evidence that the system created at RHIC undergoes a collective transverse expansion.

  4. Azimuthal dependence of pion source radii in Pb+Au collisions at 158A GeV/c

    International Nuclear Information System (INIS)

    Adamova, D.; Kushpil, V.; Sumbera, M.; Agakichiev, G.; Belaga, V.; Fomenko, K.; Panebrattsev, Y.; Petchenova, O.; Shimansky, S.; Yurevich, V.; Andronic, A.; Braun-Munzinger, P.; Garabatos, C.; Hering, G.; Holeczek, J.; Maas, A.; Marin, A.; Miskowiec, D.; Rak, J.; Sako, H.

    2008-01-01

    We present results of a two-pion correlation analysis performed with the Pb+Au collision data collected by the upgraded CERES experiment in the fall of 2000. The analysis was done in bins of the reaction centrality and the pion azimuthal emission angle with respect to the reaction plane. The pion source, deduced from the data, is slightly elongated in the direction perpendicular to the reaction plane, similarly as was observed at the Brookhaven National Laboratory Alternating Gradient Synchrotron and Relativistic Heavy Ion Collider

  5. Azimuthal dependence of pion source radii in Pb+Au collisions at 158A GeV/c

    Science.gov (United States)

    Adamová, D.; Agakichiev, G.; Andronic, A.; Antończyk, D.; Appelshäuser, H.; Belaga, V.; Bielčíková, J.; Braun-Munzinger, P.; Busch, O.; Cherlin, A.; Damjanović, S.; Dietel, T.; Dietrich, L.; Drees, A.; Dubitzky, W.; Esumi, S. I.; Filimonov, K.; Fomenko, K.; Fraenkel, Z.; Garabatos, C.; Glässel, P.; Hering, G.; Holeczek, J.; Kalisky, M.; Kniege, S.; Kushpil, V.; Maas, A.; Marín, A.; Milošević, J.; Miśkowiec, D.; Ortega, R.; Panebrattsev, Y.; Petchenova, O.; Petráček, V.; Płoskoń, M.; Radomski, S.; Rak, J.; Ravinovich, I.; Rehak, P.; Sako, H.; Schmitz, W.; Schuchmann, S.; Schukraft, J.; Sedykh, S.; Shimansky, S.; Soualah, R.; Stachel, J.; Šumbera, M.; Tilsner, H.; Tserruya, I.; Tsiledakis, G.; Wessels, J. P.; Wienold, T.; Wurm, J. P.; Yurevich, S.; Yurevich, V.

    2008-12-01

    We present results of a two-pion correlation analysis performed with the Pb+Au collision data collected by the upgraded CERES experiment in the fall of 2000. The analysis was done in bins of the reaction centrality and the pion azimuthal emission angle with respect to the reaction plane. The pion source, deduced from the data, is slightly elongated in the direction perpendicular to the reaction plane, similarly as was observed at the Brookhaven National Laboratory Alternating Gradient Synchrotron and Relativistic Heavy Ion Collider.

  6. Pion-induced knock-out reactions

    International Nuclear Information System (INIS)

    Jain, B.K.; Phatak, S.C.

    1977-01-01

    A strong absorption model for pion-induced Knock-out reactions is proposed. The distortion of the in-coming and out-going pions has been included by (1) computing pion wave number in nuclear medium (dispersive effect) and (2) excluding the central region of the nucleus where the real pion-absorption is dominant (absorption effect). In order to study the dependence of the (π + π + p) reaction on the off-shell pion-nucleon t-matrix, different off-shell extrapolations are used. The magnitude of the cross-sections seems to be sensitive to the type of off-shell extrapolation; their shapes, however, are similar. The theoretical results are compared with experimental data. The agreement between the theoretical results for separable off-shell extrapolation and the data is good. (author)

  7. Nucleon multiplicities after pion absorption in 160

    International Nuclear Information System (INIS)

    Hamers, R.

    1989-01-01

    The experiment described in this thesis concerns a simultaneous measurement of two- and higher-fold coincidences following positive and negative pion absorption in 16 0. The detected particles are protons, neutrons and deuterons. The detection and analysis of charged particles is discussed. The incident pion energy was 65 MeV, thus well below the delta resonance. The low pion energy was 65 MeV, thus well below the delta resonance. The low pion energy ensures that contributions of initial state interactions, i.e. pion-nucleon scattering preceding absorption, are minimized. The following reaction channels were selected and analyzed: π + ,pp), (π + ,pd). Evidence for quasifree reaction precessed has been investigated by comparing the data with phase-space calculations incorporating the geometry of the experimental setup. (author). 36 refs.; 1 figs.; 3 tabs

  8. Longitudinal Electroproduction of Charged Pions from

    International Nuclear Information System (INIS)

    David Gaskell; Abdellah Ahmidouch; Pawel Ambrozewicz; H. Anklin; John Arrington; K. Assamagan; Steven Avery; Kevin Bailey; Oliver K. Baker; Shelton Beedoe; Elizabeth Beise; Herbert Breuer; D. S. Brown; Roger Carlini; Jinseok Cha; Nicholas Chant; Anthony Cowley; Samuel Danagoulian; D. De Schepper; Jim Dunne; Dipangkar Dutta; Rolf Ent; Liping Gan; Ashot Gasparian; Donald Geesaman; Ron Gilman; Charles Glashausser; Paul Gueye; M. Harvey; O. Hashimoto; Wendy Hinton; G. Hofman; Ceasar Jackson; Hal Jackson; Cynthia Keppel; Ed Kinney; Doug Koltenuk; G. Kyle; Allison Lung; David Mack; D. McKee; Joseph Mitchell; Hamlet Mkrtchyan; B. Mueller; Gabriel Niculescu; Ioana Niculescu; Tom O'Neill; V. Papavassiliou; Dave Potterveld; Juerg Reinhold; Philip Roos; Reyad Sawafta; Ralph Segel; Stepan Stepanyan; Vardan Tadevosyan; T. Takahashi; Liguang Tang; B. Terburg; D. Van Westrum; J. Volmer; T. P. Welch; Stephen Wood; Lulin Yuan; Ben Zeidman; Beni Zihlmann

    2001-01-01

    Separated longitudinal and transverse cross sections for charged pion electroproduction from 1 H, 2 H, and 3 He were measured at Q 2 = 0.4 (GeV/c) 2 for two values of the invariant mass, (bar W) = 1.15 GeV and (bar W) = 1.60 GeV, in a search for a mass dependence which would signal the effect of nuclear pions. This is the first such study that includes recoil momenta significantly above the Fermi surface. The longitudinal cross section, if dominated by the pion-pole process, should be sensitive to nuclear pion currents. Comparisons of the longitudinal cross section target ratios to a quasifree calculation reveal a significant suppression in 3> He at (bar W) = 1.60 GeV. The (bar W) = 1.15 GeV results are consistent with simple estimates of the effect of nuclear pion currents, but are also consistent with pure quasifree production

  9. Diffractive pion dissociation into 5 pion final states at COMPASS

    Energy Technology Data Exchange (ETDEWEB)

    Neubert, Sebastian; Friedrich, Jan; Grabmueller, Stefanie; Haas, Florian; Ketzer, Bernhard; Paul, Stephan; Weitzel, Quirin [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany); Chung, Suh-Urk [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany); Brookhaven National Laboratory, Upton, NY 11973 (United States); Ryabchikov, Dimitry [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany); Institute for High Ernergy Physics, 142284 Protvino (Russian Federation)

    2009-07-01

    COMPASS is a fixed-target experiment at the CERN SPS, which investigates the structure and spectroscopy of hadrons. In 2004, a first run with a 190 GeV/c {pi}{sup -} beam took place using nuclear targets. Diffractive dissociation reactions observed in this run provide clean access to meson resonances with masses up to 3 GeV/c{sup 2}. Exclusive final states with 5 charged pions have been extracted. The covered range in momentum transfer extends from threshold to a few GeV{sup 2}/c{sup 2} allowing to study resonance production in different regimes. We report on the status of the analysis of this unique data set.

  10. Twist-2 Light-Cone Pion Wave Function

    OpenAIRE

    Belyaev, V. M.; Johnson, Mikkel B.

    1997-01-01

    We present an analysis of the existing constraints for the twist-2 light-cone pion wave function. We find that existing information on the pion wave function does not exclude the possibility that the pion wave function attains its asymptotic form. New bounds on the parameters of the pion wave function are presented.

  11. Influence of relaxation on emission and excitation of coherent states of electromagnetic field in the Jaynes-Cummings model

    International Nuclear Information System (INIS)

    Verlan, E.M.

    2003-01-01

    A two-level atom interacting with a field mode is considered. The field frequency is assumed to be equal to the atom transition frequency. The relaxation equations of the atom - field system are written in the basis of dressed states of the Jaynes - Cummings model taking into account quasi-resonant pumping. Their solutions are derived for a stationary regime. The average amplitude of a coherent electromagnetic field is found

  12. Chiral Dynamics in Pion-Photon Reactions Habilitation

    CERN Document Server

    Friedrich, Jan Michael

    As the lightest particle of the strong force, the pion plays a central role in the field of strong interactions, and understanding its properties is of prime relevance for understanding the strong interaction in general. The low-energy behaviour of pions is of particular interest. Although the quark-gluon substructure and their quantum chromodynamics is not apparent then, this specific inner structure causes the presence of approximate symmetries in pion-pion interactions and in pion decays, which gives rise to the systematic description of processes involving pions in terms of few low-energy constants. Specifically, the chiral symmetry and its spontaneous and explicit breaking, treated in chiral perturbation theory (ChPT), leads to firm predictions for low-energy properties of the pion. To those belong the electromagnetic polarisabilities of the pion, describing the leading-order structure effect in pion Compton scattering. The research presented in this work is concerned with the interaction of pions and ph...

  13. Learning about nucleon resonances with pion photoproduction

    International Nuclear Information System (INIS)

    Walker, R.L.

    1989-01-01

    This chapter charts the discovery of nucleon resonances from pion-nucleon interactions. It was not until after the Albuquerque meeting in 1953 the experimentalists were able to persuade physicists about the existence of this phenomenon with the discovery of the P 33 resonance. The second and third resonances to be discovered, D 13 and F 15 , were seen as peaks in the total cross section for pion plus photoproduction, from 1956 onwards. Knowledge of pion-nucleon scattering has played an important role in the development of quark models. (UK)

  14. Landau-Migdal parameters and pion condensation

    Energy Technology Data Exchange (ETDEWEB)

    Tatsumi, Toshitaka [Department of Physics, Kyoto Univ., Kyoto (Japan)

    1999-08-01

    The possibility of pion condensation, one of the long-standing issues in nuclear physics, is reexamined in the light of the recent experimental data on the giant Gamow-Teller resonance. The experimental result tells that the coupling of nucleon particle-hole states with {delta} isobar-hole states in the spin-isospin channel should be weaker than that previously believed. It, in turn, implies that nuclear matter has the making of pion condensation at low densities. The possibility and implications of pion condensation in the heavy-ion collisions and neutron stars should be seriously reconsidered. (author)

  15. A measurement of the pion charge radius

    International Nuclear Information System (INIS)

    Amendolia, S.R.; Badelek, B.; Batignani, G.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giazotto, A.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Ristori, L.; Scribano, A.; Tonelli, G.; Codino, A.; Fabbri, F.L.; Laurelli, P.; Satta, L.; Spillantini, P.; Zallo, A.; Counihan, M.J.; Frank, S.G.F.; Harvey, J.; Storey, D.; Menasce, D.; Meroni, E.; Moroni, L.

    1984-01-01

    We report a measurement of the negative pion electromagnetic form factor in the range of space-like four-momentum transfer 0.014 2 2 . The measurement was made by the NA7 collaboration at the CERN SPS, by observing the interaction of 300 GeV pions with the electrons of a liquid hydrogen target. The form factor is fitted by a pole form with a pion radius of (rho 2 )sup(1/2) = 0.657 +- 0.012 fm. (orig.)

  16. Negative pion irradiation of mammalian cells

    International Nuclear Information System (INIS)

    Dertinger, H.; Luecke-Huhle, C.; Schlag, H.; Weibezahn, K.F.

    1976-01-01

    Monolayers and spheroids of Chinese hamster cells (V79) were subjected to negative pion irradiation under aerobic conditions. R.b.e. values in the pion peak of 1.8 and 1.5 were obtained for monolayers and spheroids, respectively, whereas the r.b.e. for the plateau was found to be slightly higher than 1. In addition, it was observed that the higher resistance of the V79 spheroid cells than the monolayers to γ-irradiation is not diminished in the pion peak, suggesting that the underlying phenomenon of intercellular communication influences cell survival even after high-LET irradiation. (author)

  17. A new determination of the pion mass

    International Nuclear Information System (INIS)

    Anagnastopoulos, D.; Belmiloud, D.; El-Khoury, P.; Indelicato, P.; Borchert, G.; Gorke, H.; Gotta, D.; Lenz, S.; Siems, T.; Daum, M.; Frosch, R.; Hauser, P.; Kirch, K.; Simons, L.M.

    1996-01-01

    Initial measurements concerning the feasibility of a new pion mass determination are described. In a first step, a high-resolution crystal spectrometer was coupled to a cyclotron trap which provides a high pion stopping density, sufficient to check predictions for the cascade process and to measure the stability of the apparatus. A comparison with the measured Cu K α fluorescence line resolves an ambiguity in the value of the pion mass. The preliminary result from this experiment is m π -=(139.57040±0.00045) MeV/c 2 . (orig.)

  18. The pion pole term in electroproduction of off-mass-shell pions

    International Nuclear Information System (INIS)

    McKellar, B.H.; Ellis, R.G.

    1983-01-01

    The dependence of the invariant amplitudes for electroproduction of off-mass-shell pions on the pion Born term is investigated when current algebra Ward identities and PCAC are used to determine pion electroproduction invariant amplitudes. The authors show that an amplitude satisfying the Ward identities can be constructed starting from the usual Born terms which do not satisfy them and that this same amplitude will be obtained for a large class of input Born terms

  19. Coherent and incoherent giant dipole resonance γ-ray emission induced by heavy ion collisions: Study of the 40Ca+48Ca system by means of the constrained molecular dynamics model

    International Nuclear Information System (INIS)

    Papa, Massimo; Cardella, Giuseppe; Bonanno, Antonio; Pappalardo, Giuseppe; Rizzo, Francesca; Amorini, Francesca; Bonasera, Aldo; Di Pietro, Alessia; Figuera, Pier Paolo; Tudisco, Salvatore; Maruyama, Toshiki

    2003-01-01

    Coherent and incoherent dipolar γ-ray emission is studied in a fully dynamical approach by means of the constrained molecular dynamics model. The study is focused on the system 40 Ca+ 48 Ca for which recently experimental data have been collected at 25 MeV/nucleon. The approach allows us to explain the experimental results in a self-consistent way without using statistical or hybrid models. Moreover, calculations performed at higher energy show interesting correlations between the fragment formation process, the degree of collectivity, and the coherence degree of the γ-ray emission process

  20. Low energy pion-pion phase shifts from chiral perturbation theory

    International Nuclear Information System (INIS)

    Borges, J. Sa; Barbosa, J. Soares; Oguri, V.

    1997-01-01

    The low energy pion-pion S- and P- experimental phase-shifts are fitted with chiral perturbation theory (Ch PT) amplitude. The low energy pion-pion S- and P- experimental phase-shifts. The parameters l 1 and l 2 of the one loop corrected amplitude are fixed and the corresponding values of the scattering lengths are calculated. We propose that the present method is the best way to fix Ch P T parameters. The unitarization program of current algebra is also discussed. (author)

  1. Electroproduction of the neutral pion off 4He

    Energy Technology Data Exchange (ETDEWEB)

    Torayev, Bayram [Old Dominion Univ., Norfolk, VA (United States)

    2016-12-01

    Deeply virtual exclusive processes offer a unique opportunity to study the internal structure of the nucleon and nuclei. The goal of this work is to extract the beam-spin asymmetry in deeply virtual coherent neutral pion electroproduction, e^4He to e'^4He'pi^0, using the CLAS detector in the experimental Hall B at Thomas Jefferson National Accelerator Facility. The data were collected in 2009 with a 6 GeV longitudinally polarized electron beam impinging on a 30 cm long, 6 atm Helium-4 gaseous target. In order to ensure that the process is coherent, a new Radial Time Projection Chamber was used to detect and identify low energy recoil a-particles. The Beam Spin Asymmetry in the coherent deep exclusive regime was measured at Q^2 = 1.50 GeV^2, xB = 0.18 and -t = 0.14 GeV^2. The measured asymmetry has an amplitude of 10%+/-5% and has the opposite sign compared the asymmetry measured for pi^0 production on the proton.

  2. Electron linac design for pion radiotherapy

    International Nuclear Information System (INIS)

    Loew, G.A.; Brown, K.L.; Miller, R.H.; Walz, D.R.

    1977-03-01

    The electron linac provides a straightforward, state-of-the-art method of producing the primary beam required for a hospital-based multiport pion radiotherapy facility for cancer treatment. The accelerator and associated beam transport system described are capable of generating an electron beam of about 250 kW and delivering it alternately to one of several pion generators and treatment areas. Each pion generator, a prototype of which now exists at the Stanford W. W. Hansen Laboratory, would contain a target for the electron beam and sixty separate superconducting magnet channels which focus the pions in the patient. The considerations which enter the design of a practical linac are presented together with a possible layout of a flexible beam transport system

  3. Factorization and pion form factor in QCD

    International Nuclear Information System (INIS)

    Efremov, A.V.; Radyushkin, A.V.

    1979-01-01

    The behaviour of the pion electromagnetic form factor (EMFF) in the framework of quantum chromodynamics (QCD) is discussed. Pion is considered to be a quark-antiquark bound state. It is proposed to use an OPE description of the bound state structure by matrix elements of certain local gauge-invariant operators. Short-distance quark interactions is proved using a direct analysis of perturbation theory in the α-parametric representation of the Feynman diagrams. It is shown that the short-distance parton picture privides a self-consistent description of the large Q 2 momentum behaviour of the pion EMFF in QCD. Pion EMFF asymptotics is expressed in terms of fu fundamental constants of the theory

  4. Pion photoproduction on the nucleon at threshold

    International Nuclear Information System (INIS)

    Cheon, I.T.; Jeong, M.T.

    1989-08-01

    Electric dipole amplitudes of pion photoproduction on the nucleon at threshold have been calculated in the framework of the chiral bag model. Our results are in good agreement with the existing experimental data

  5. Pion-nucleus cross sections approximation

    International Nuclear Information System (INIS)

    Barashenkov, V.S.; Polanski, A.; Sosnin, A.N.

    1990-01-01

    Analytical approximation of pion-nucleus elastic and inelastic interaction cross-section is suggested, with could be applied in the energy range exceeding several dozens of MeV for nuclei heavier than beryllium. 3 refs.; 4 tabs

  6. Low energy theorems in pion production

    International Nuclear Information System (INIS)

    Holstein, B.R.; Washington Univ., Seattle, WA

    1992-01-01

    Considerable activity-both theoretical and experimental-has recently taken place involving the threshold and near threshold of pion photo- and electroproduction. This activity is herein summarized and a program for future work is outlined

  7. Pion interferometric tests of transport models

    Energy Technology Data Exchange (ETDEWEB)

    Padula, S.S.; Gyulassy, M.; Gavin, S. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.)

    1990-01-08

    In hadronic reactions, the usual space-time interpretation of pion interferometry often breaks down due to strong correlations between spatial and momentum coordinates. We derive a general interferometry formula based on the Wigner density formalism that allows for arbitrary phase space and multiparticle correlations. Correction terms due to intermediate state pion cascading are derived using semiclassical hadronic transport theory. Finite wave packets are used to reveal the sensitivity of pion interference effects on the details of the production dynamics. The covariant generalization of the formula is shown to be equivalent to the formula derived via an alternate current ensemble formalism for minimal wave packets and reduces in the nonrelativistic limit to a formula derived by Pratt. The final expression is ideally suited for pion interferometric tests of Monte Carlo transport models. Examples involving gaussian and inside-outside phase space distributions are considered. (orig.).

  8. Pion interferometric tests of transport models

    International Nuclear Information System (INIS)

    Padula, S.S.; Gyulassy, M.; Gavin, S.

    1990-01-01

    In hadronic reactions, the usual space-time interpretation of pion interferometry often breaks down due to strong correlations between spatial and momentum coordinates. We derive a general interferometry formula based on the Wigner density formalism that allows for arbitrary phase space and multiparticle correlations. Correction terms due to intermediate state pion cascading are derived using semiclassical hadronic transport theory. Finite wave packets are used to reveal the sensitivity of pion interference effects on the details of the production dynamics. The covariant generalization of the formula is shown to be equivalent to the formula derived via an alternate current ensemble formalism for minimal wave packets and reduces in the nonrelativistic limit to a formula derived by Pratt. The final expression is ideally suited for pion interferometric tests of Monte Carlo transport models. Examples involving gaussian and inside-outside phase space distributions are considered. (orig.)

  9. Charged pions polarizability measurement at COMPASS

    CERN Document Server

    Guskov, A

    2010-01-01

    The pion electromagnetic structure can be probed in $\\pi^{−}+(A,Z)\\rightarrow\\pi^{-}+(A,Z)+\\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric $(\\alpha_{\\pi})$ and the magnetic $(\\beta_{\\pi})$ polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of point-like pions with the measured cross section. The opportunity to measure pion polarizability via the Primakoff reaction at the COMPASS experiment was studied with $a$ $\\pi^{-}$ beam of 190 GeV during pilot run 2004. The obtained results were used for preparation of the new data taking which was performed in 2009.

  10. Radiobiological comparison of pions and heavy ions

    International Nuclear Information System (INIS)

    Raju, M.R.

    1981-01-01

    The physical and radiobiological differences between some aspects of pions and heavy ions are discussed, followed by a discussion of acute and late effects of high LET radiations compared to low LET radiations

  11. Direct determination of two-pion correlations for $\\overline{p}p \\to 2\\pi^{+}2\\pi^{-}$ annihilation at rest

    CERN Document Server

    Angelopoulos, Angelos; Aslanides, Elie; Backenstoss, Gerhard; Bargassa, P; Behnke, O; Benelli, A; Bertin, V; Blanc, F; Bloch, P; Carlson, P J; Carroll, M; Carvalho, J; Cawley, E; Charalambous, S; Chardin, G; Chertok, M B; Cody, A; Danielsson, M; Dejardin, M; Derré, J; Ealet, A; Eleftheriadis, C; Evangelou, I; Faravel, L; Ferreira-Marques, R; Fetscher, W; Fidecaro, Maria; Filipcic, A; Francis, D; Fry, J; Gabathuler, Erwin; Gamet, R; Garreta, D; Gerber, H J; Go, A; Haselden, A; Hayman, P J; Henry-Coüannier, F; Hollander, R W; Hubert, E; Jon-And, K; Kettle, P R; Kokkas, P; Kreuger, R; Le Gac, R; Leimgruber, F; Liolios, A; Machado, E; Mandic, I; Manthos, N; Marel, Gérard; Mikuz, M; Miller, J; Montanet, François; Müller, A; Nakada, Tatsuya; Pagels, B; Papadopoulos, I M; Pavlopoulos, P; Pinto da Cunha, J; Policarpo, Armando; Polivka, G; Rickenbach, R; Roberts, B L; Ruf, T; Sakelliou, L; Sanders, P; Schäfer, M; Schaller, L A; Schietinger, T; Schopper, A; Soares, A; Tauscher, Ludwig; Thibault, C; Touchard, F; Touramanis, C; Triantis, F A; Van Beveren, E; van Eijk, C W E; Vlachos, S; Weber, P; Wigger, O; Wolter, M; Yéche, C; Zavrtanik, D; Zimmerman, D; Locher, M P; Markushin, V E

    1998-01-01

    We study $\\pi\\pi$ correlations in the exclusive reaction $\\ppb \\to 2\\pi^+2\\pi^-$ at rest measured by the CPLEAR experiment. Avoiding the introduction of an arbitrary reference sample, we analyse differential distributions for equal charge pion pairs removing the phase-space factor event by event. A peak at small relative momenta is most pronounced for large total momentum of the pair. The physical implications of bosonic symmetrization for the properties of the pion source, in particular its radius, are briefly discussed. The two extremes considered are the chaotic Hanbury-Brown--Twiss mechanism and the coherent Skyrmion model.

  12. Pion-nucleon scattering and isospin violation

    International Nuclear Information System (INIS)

    Meissner, U.G.

    1999-01-01

    The paper discusses low-energy pion-nucleon scattering in the framework of chiral perturbation theory. It is argued that using this theoretical method one is able to match the in some cases impressive experimental accuracy (for the low partial waves). It is also shown how strong and electromagnetic isospin violation can be treated simultaneously. Some first results for neutral pion scattering and the σ-term are given. Copyright (1999) World Scientific Publishing Co. Pte. Ltd

  13. Antiquark distributions in pion and nucleon

    International Nuclear Information System (INIS)

    Arakelian, G.G.; Boreskov, K.G.; Kaidalov, A.B.

    1980-01-01

    Relation between the antiquark distributions in pion and nucleon, based on the π-exchange hypothesis, is derived. The antiquark distributions in proton are calculated with the data on the valence antiquark distribution in pion as input. Results of the calculation agree with the experimental data. The role of the peripheral mechanism in formulation of the initial conditions for the chromodynamical evolution equations is discussed

  14. Pion condensation and neutron star dynamics

    International Nuclear Information System (INIS)

    Kaempfer, B.

    1983-01-01

    The question of formation of pion condensate via a phase transition in nuclear matter, especially in the core of neutron stars is reviewed. The possible mechanisms and the theoretical restrictions of pion condensation are summarized. The effects of ultradense equation of state and density jumps on the possible condensation phase transition are investigated. The possibilities of observation of condensation process are described. (D.Gy.)

  15. Pion production cross sections and associated parameters

    International Nuclear Information System (INIS)

    Bradbury, J.N.

    1985-01-01

    Negative pions have been used for radiotherapy at the meson factories LAMPF (USA), SIN (Switzerland), and TRIUMF (Canada) and have been planned for use at new meson facilities under construction (USSR) and at proposed dedicated medical facilities. Providing therapeutically useful dose rates of pions requires a knowledge of the pion production cross sections as a function of primary proton energy (500 to 1000 MeV), pion energy (less than or equal to100 MeV), production angle, and target material. The current status of the data base in this area is presented including theoretical guidelines for extrapolation purposes. The target material and geometry, as well as the proton and pion beam parameters, will affect the electron (and muon) contamination in the beam which may have an important effect on both the LET characteristics of the dose and the dose distribution. In addition to cross-section data, channel characteristics such as length of pion trajectory, solid-angle acceptance, and momentum analysis will affect dose rate, distribution, and quality. Such considerations are briefly addressed in terms of existing facilities and proposed systems. 16 refs., 6 figs

  16. Interaction of slow pions with atomic nuclei

    International Nuclear Information System (INIS)

    Troitskij, M.A.; Tsybul'nikov, A.V.; Chekunaev, N.I.

    1984-01-01

    Interactions of slow pions with atomic nuclei near to pion condensation are investigated. From comparison of experimental data with the theoretical calculation results on the basis of precise microscopic approach not bound with the random phase approximation (RPA) nuclear matter fundamental parameters near a critical point can be found. Optical potential of slow pions in nuclei, πN-scattering amplitudes and lengths, π-atom level isotopic shift, phenomenon of single-nucleon pion absorption by nucleus, phenomenon of nuclear critical opalescence are considered. The results of πN-scattering lengths calculation, sup(40-44)Ca, sup(24-29)Mg, sup(16-18)O π-atom level shift are presented. It is shown that the presence of π-condensate in nuclei can explain the observed suppression of p-wave potential terms. The phenomenon of single-nucleon pion absorption by nucleus is one of direct experiments which permits to reveal the π-condensate. The nuclear opalescence phenomenon is manifested in increase of pion photoproduction reaction cross section for account of nucleus proximity to π-condensation as compared with the calculated in the Fermi-gas model. The suggested method for calculating precondensate phenomena operates the better, the nearer is the system to the condensation threshold whereas the RPA method in this region is inapplicable

  17. Effects of ρ-meson width on pion distributions in heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Pasi Huovinen

    2017-06-01

    Full Text Available The influence of the finite width of ρ meson on the pion momentum distribution is studied quantitatively in the framework of the S-matrix approach combined with a blast-wave model to describe particle emissions from an expanding fireball. We find that the proper treatment of resonances which accounts for their production dynamics encoded in data for partial wave scattering amplitudes can substantially modify spectra of daughter particles originating in their two body decays. In particular, it results in an enhancement of the low-pT pions from the decays of ρ mesons which improves the quantitative description of the pion spectra in heavy ion collisions obtained by the ALICE collaboration at the LHC energy.

  18. Coherent terahertz emission from Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} intrinsic Josephson junction stacks

    Energy Technology Data Exchange (ETDEWEB)

    Rudau, Fabian; Gross, Boris; Wieland, Raphael; Judd, Thomas; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Collective Quantum Phenomena in LISA" +, Universitaet Tuebingen, Tuebingen (Germany); Kinev, Nickolay; Koshelets, Valery [Kotel' nikov Institute of Radio Engineering and Electronics, Moscow (Russian Federation); Tsujimoto, Manabu [Kyoto University, Kyoto (Japan); Ji, Min; Huang, Ya; Zhou, Xianjing; An, Deyue; Wang, Huabing [National Institute for Materials Science, Tsukuba (Japan); Research Institute of Superconductor Electronics, Nanjing University, Nanjing (China); Wu, Peiheng [Research Institute of Superconductor Electronics, Nanjing University, Nanjing (China); Hatano, Takeshi [National Institute for Materials Science, Tsukuba (Japan)

    2015-07-01

    Stacks of intrinsic Josephson junctions, made of the high temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, are promising candidates to be used as generators of electromagnetic waves in the terahertz regime, in principle allowing frequencies up to ∝10 THz. Ranging from 0.4 to 1 THz, coherent emission was detected from large, rectangular stacks, producing several tens of microwatt in power. Despite of several years of research, the mechanism of synchronizing all the junctions in the stack is still not fully understood. We investigated the heat distribution and electromagnetic standing waves in such stacks, as well as the generation of terahertz radiation, using a combination of electric transport measurements, direct radiation detection and low temperature scanning laser microscopy. Recent experimental results from our collaboration will be presented and compared to numerical simulations.

  19. Determination of the pion-nucleon coupling constant and scattering lengths

    International Nuclear Information System (INIS)

    Ericson, T.E.O.; Loiseau, B.; Thomas, A.W.

    2002-01-01

    We critically evaluate the isovector Goldberger-Miyazawa-Oehme (GMO) sum rule for forward πN scattering using the recent precision measurements of π - p and π - d scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data, g c 2 (GMO)/4π=14.11±0.05(statistical)±0.19(systematic) or f c 2 /4π=0.0783(11). This value is intermediate between that of indirect methods and the direct determination from backward np differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the pion-proton and pion-neutron scattering lengths with high precision, namely, (a π - p +a π - n )/2=[-12±2(statistical)±8(systematic)]x10 -4 m π -1 and (a π - p -a π - n )/2=[895±3(statistical)±13 (systematic)]x10 -4 m π -1 . For the need of the present analysis, we improve the theoretical description of the pion-deuteron scattering length

  20. Soliton bag model of the nucleon and delta dressed by a quark-antiquark pion

    International Nuclear Information System (INIS)

    Dethier, J.L.L.

    1985-01-01

    The Friedberg-Lee soliton bag model is used to describe the nucleon, delta and pion. The author builds upon the mean-field solutions to the model taking into account the one-gluon-exchange interaction by the use of a free gluon propagator in the Coulomb gauge and allowing the nucleon or delta to consist of a bare three quark bag and a three quark bag dressed by one quark-antiquark pion. This way of treating the pion cloud differs from most other works on the subject by the fact that he takes the quark substructure of the pion into account. The generator coordinate method enables him to find an approximate solution to the ground state of the nucleon and the delta from which static physical properties can be calculated. The soliton field part of the ground state is treated in a coherent state approximation (similar to the mean-field approximation, but remaining a true quantum state). The generator coordinate or Hill-Wheeler integral equations are solved numerically with the help of the Tikhonov regularization. Detailed numerical results are given for different sets of parameters. The agreement with experiment is as good as in the mean-field approximation but new quantities are now accessible to computation (e.g., the neutron charge radius and the NN[ and NΔπ coupling constants

  1. Elastic and inelastic pion reactions on few nucleon systems

    International Nuclear Information System (INIS)

    Lensky, V.

    2007-01-01

    In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)

  2. Elastic and inelastic pion reactions on few nucleon systems

    Energy Technology Data Exchange (ETDEWEB)

    Lensky, V.

    2007-09-29

    In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)

  3. Isotopic spin effect in three-pion Bose-Einstein correlations

    International Nuclear Information System (INIS)

    Suzuki, N.

    1998-01-01

    Bose-Einstein (BE) correlations of identical particles in multiple production processes are extensively studied last years because they give an information on the space-time region of interaction. The basic effect is analogous to Hanbury-Brown - Twiss (HBT) interferometry in optics and suggests statistical production of the particles (mainly π mesons). The possible presence of coherent pionic component (for example, in the case of disoriented chiral condensate formation) modifies the HBT effect. On the other hand, the pions (contrary to photons) are subject to isotopic spin (and electric charge) conservation and so they can not be emitted independently. While the corresponding change of the statistical part is not essential for large multiplicities, the coherent part changes substantially when isotopic spin conservation is taken into account. BE correlations of the pions in the presence of both statistical and coherent components are reconsidered taking into account isotopic spin conservation in the coherent part. That will result in appearance of additional contribution to pionic correlation function. (author)

  4. Coherent emission of terahertz radiation from intrinsic Josephson junctions in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Rudau, Fabian; Wieland, Raphael; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universitaet Tuebingen (Germany); Zhou, Xianjing; Ji, Min; Hao, Luyao; Huang, Ya; Wang, Huabing [Research Institute of Superconductor Electronics, Nanjing University (China); National Institute for Materials Science, Tsukuba (Japan); Kinev, Nickolay; Koshelets, Valery [Kotel' nikov Institute of Radio Engineering and Electronics, Moscow (Russian Federation); Li, Jun; Wu, Peiheng [Research Institute of Superconductor Electronics, Nanjing University (China); Hatano, Takeshi [National Institute for Materials Science, Tsukuba (Japan)

    2016-07-01

    Stacks of intrinsic Josephson junctions, made of the high-T{sub c} superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, can be used as emitters of electromagnetic waves at terahertz frequencies. Coherent emission from 0.3 to 2.4 THz was detected from large, rectangular or disc-shaped mesa structures. Having a linewidth of only a few MHz, emission powers of several tens of microwatt can be produced for single stacks and up to 0.61 mW for an array of mesas. Since the mechanisms of synchronizing all the junctions in the stack is still not fully understood, we investigated the temperature distribution and electromagnetic standing waves in such stacks, as well as the generation of terahertz radiation, using a combination of electric transport measurements, direct radiation detection and low temperature scanning laser microscopy. Recent experimental results from our collaboration will be presented and compared to numerical simulations.

  5. Narrow coherent effects in πNN-dynamics

    International Nuclear Information System (INIS)

    Kudryavtsev, A.E.; Obrant, G.Z.

    1990-01-01

    Coherent effect production is considered in πNN-dynamics with resonant pion-nucleon interaction via Brueckner theory and Faddev equations. It is shown that the narrow energy and final momentum dependence can arise in the inelastic S-wave πd-scattering. The energy dependence peculiarities can have a width an order magnitude less than πN-resonance one

  6. Effect of pion mean-field on properties of pions and kaons from heavy-ion collisions

    International Nuclear Information System (INIS)

    Zheng Yuming; Chu Zili; Wang Hui; Sa Benhao

    1996-01-01

    The Relativistic Vlasov-Uehling-Uhlenbeck (RVUU) model is used to study the properties of pions and kaons produced in heavy ion collisions. We include the nuclear medium effect on kaon and pion in the model, and simulate pion production and subthreshold kaon production in Kr + Zr reactions at 1 GeV/u. The calculated results show that the attractive pion optical potential changes the final-state pion momentum spectrum, enhancing the yield of pions with low transverse momenta. At the same time it also increases the kaon abundance and modifies the kaon momentum distribution

  7. Measurement of the charged-pion polarizability.

    Science.gov (United States)

    Adolph, C; Akhunzyanov, R; Alexeev, M G; Alexeev, G D; Amoroso, A; Andrieux, V; Anosov, V; Austregesilo, A; Badełek, B; Balestra, F; Barth, J; Baum, G; Beck, R; Bedfer, Y; Berlin, A; Bernhard, J; Bicker, K; Bieling, J; Birsa, R; Bisplinghoff, J; Bodlak, M; Boer, M; Bordalo, P; Bradamante, F; Braun, C; Bressan, A; Büchele, M; Burtin, E; Capozza, L; Chiosso, M; Chung, S U; Cicuttin, A; Colantoni, M; Crespo, M L; Curiel, Q; Dalla Torre, S; Dasgupta, S S; Dasgupta, S; Denisov, O Yu; Dinkelbach, A M; Donskov, S V; Doshita, N; Duic, V; Dünnweber, W; Dziewiecki, M; Efremov, A; Elia, C; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Filin, A; Finger, M; Finger, M; Fischer, H; Franco, C; du Fresne von Hohenesche, N; Friedrich, J M; Frolov, V; Gautheron, F; Gavrichtchouk, O P; Gerassimov, S; Geyer, R; Gnesi, I; Gobbo, B; Goertz, S; Gorzellik, M; Grabmüller, S; Grasso, A; Grube, B; Grussenmeyer, T; Guskov, A; Guthörl, T; Haas, F; von Harrach, D; Hahne, D; Hashimoto, R; Heinsius, F H; Herrmann, F; Hinterberger, F; Höppner, Ch; Horikawa, N; d'Hose, N; Huber, S; Ishimoto, S; Ivanov, A; Ivanshin, Yu; Iwata, T; Jahn, R; Jary, V; Jasinski, P; Jörg, P; Joosten, R; Kabuss, E; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koivuniemi, J H; Kolosov, V N; Kondo, K; Königsmann, K; Konorov, I; Konstantinov, V F; Kotzinian, A M; Kouznetsov, O; Krämer, M; Kroumchtein, Z V; Kuchinski, N; Kuhn, R; Kunne, F; Kurek, K; Kurjata, R P; Lednev, A A; Lehmann, A; Levillain, M; Levorato, S; Lichtenstadt, J; Maggiora, A; Magnon, A; Makke, N; Mallot, G K; Marchand, C; Martin, A; Marzec, J; Matousek, J; Matsuda, H; Matsuda, T; Meshcheryakov, G; Meyer, W; Michigami, T; Mikhailov, Yu V; Miyachi, Y; Moinester, M A; Nagaytsev, A; Nagel, T; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Novy, J; Nowak, W-D; Nunes, A S; Olshevsky, A G; Orlov, I; Ostrick, M; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S; Peshekhonov, D; Platchkov, S; Pochodzalla, J; Polyakov, V A; Pretz, J; Quaresma, M; Quintans, C; Ramos, S; Regali, C; Reicherz, G; Rocco, E; Rossiyskaya, N S; Ryabchikov, D I; Rychter, A; Samoylenko, V D; Sandacz, A; Sarkar, S; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C; Schlüter, T; Schmidt, K; Schmieden, H; Schönning, K; Schopferer, S; Schott, M; Shevchenko, O Yu; Silva, L; Sinha, L; Sirtl, S; Slunecka, M; Sosio, S; Sozzi, F; Srnka, A; Steiger, L; Stolarski, M; Sulc, M; Sulej, R; Suzuki, H; Szabelski, A; Szameitat, T; Sznajder, P; Takekawa, S; ter Wolbeek, J; Tessaro, S; Tessarotto, F; Thibaud, F; Uhl, S; Uman, I; Virius, M; Wang, L; Weisrock, T; Wilfert, M; Windmolders, R; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zink, A

    2015-02-13

    The COMPASS collaboration at CERN has investigated pion Compton scattering, π(-)γ→π(-)γ, at center-of-mass energy below 3.5 pion masses. The process is embedded in the reaction π(-)Ni→π(-)γNi, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q(2)<0.0015  (GeV/c)(2). From a sample of 63,000 events, the pion electric polarizability is determined to be α(π)=(2.0±0.6(stat)±0.7(syst))×10(-4)  fm(3) under the assumption α(π)=-β(π), which relates the electric and magnetic dipole polarizabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambiguously known, was performed for an independent estimate of the systematic uncertainty.

  8. On two-particle correlations of identical pions

    International Nuclear Information System (INIS)

    Podgoretskij, M.I.

    1991-01-01

    The pion generation processes, in which the interference term describing the correlations of identical pions seems to be negative, have been analyzed. It is shown that similar processes can take place, in particular, in nuclear collisions at intermediate energies

  9. Low-energy photo- and electroproduction for physical pions

    International Nuclear Information System (INIS)

    MacMullen, J.T.

    1979-02-01

    The Ward identities of current algebra are combined with gauge invariance constraints, on-shell PCAC and the Bjorken limit to obtain the low-energy expressions of the pion photo- and electroproduction invariant amplitudes for physical pions

  10. The electric conductivity of a pion gas

    International Nuclear Information System (INIS)

    Atchison, J.; Rapp, R.

    2017-01-01

    The determination of transport coefficients plays a central role in characterizing hot and dense nuclear matter. In the present work we calculate the electric conductivity of hot hadronic matter by extracting it from the ρ meson spectral function, as its zero-energy limit at vanishing momentum. Using hadronic many-body theory, we calculate the ρ meson self-energy in a pion gas. This requires the dressing of the pion propagators in the ρ self-energy with π - ρ loops, and the inclusion of vertex corrections to maintain gauge invariance. The resulting spectral function is used to calculate the electric conductivity of hot hadronic matter. In particular, we analyze the transport peak of the spectral function and extract its behavior with temperature and coupling strength. Our results suggest that, while obeying lower bounds proposed by conformal field theories in the strong-coupling limit, hot pion matter is a strongly-coupled medium. (paper)

  11. Chiral pion dynamics for spherical nucleon bags

    International Nuclear Information System (INIS)

    Vento, V.; Rho, M.; Nyman, E.M.; Jun, J.H.; Brown, G.E.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

    1980-01-01

    A chirally symmetric quark-bag model for the nucleon is obtained by introducing an explicit, classical, pion field exterior to the bag. The coupling at the bag surface is determined by the requirement of a conserved axial-vector current. The pion field satisfies equations of motion corresponding to the non-linear sigma-model. We study on this paper the simplified case where the bag and the pion field are spherically symmetric. Corrections due to gluon exchange between the quarks are ignored along with other interactions which split the N- and Δ-masses. The equations of motion for the pion field are solved and we find a substantial pion pressure at the bag surface, along with an attractive contribution to the nucleon self-energy. The total energy of the system, bag plus meson cloud, turns out to be approximately Msub(n)c 2 for a wide range of bag radii, from 1.5 fm down to about 0.5 fm. Introduction of a form factor for the pion would extend the range of possible radii to even smaller values. We propose that the bag with the smallest allowed radius be identified with the 'little bag' discussed before. One surprising result of the paper is that as long as one restricts to spherically symmetric bags, restoring chiral symmetry to the bag model makes the axial-vector current coupling constant gsub(A) to be always too large compared with the experimental value for any bag radius, suggesting a deviation from spherical symmetry for the intrinsic bag wave functions of the 'ground-state' hadrons. (orig.)

  12. Negative pion capture in chemical compounds

    International Nuclear Information System (INIS)

    Butsev, V.S.; Chultem, D.; Gavrilov, Yu.K.; Ganzorig, Dz.; Norseev, Yu.V.; Presperin, V.

    1976-01-01

    The results are reported of an experiment of determination of the probability of capture of resting negative pions by iodine nuclei in alkali metal iodides (LiI, NaI, KI, RbI, CsI). The yield of an isomer sup(116m)(Sb/8 - ) with a high spin number, formed in the reaction 127 I(π - , lp 10n) allows to determine the relative probability of the nuclear capture of pions in the above compounds. The results obrained are compared with the predictions of the Fermi-Teller Z-law

  13. Numerology on pion and proton rapidity

    International Nuclear Information System (INIS)

    Gugelot, P.C.

    1987-01-01

    The pseudo-rapidity of pion jets which were measured for 50 GeV and 150 GeV incident pions and protons on carbon, copper and lead targets is analysed. The shape of the rapidity distribution for a ''fireball'' which emits particles isotropically in its center of mass is a cosh -2 y distribution. It is possible to unfold all measured distributions into three groups which correspond to a low rapidity originating from the target fragmentation, a middle group which is a function of the center of mass of the projectile and target rapidity and a fast group which is due to the projectile. 11 refs., 8 figs. (author)

  14. Pion-induced damage in silicon detectors

    CERN Document Server

    Bates, S; Glaser, M; Lemeilleur, F; León-Florián, E; Gössling, C; Kaiser, B; Rolf, A; Wunstorf, R; Feick, H; Fretwurst, E; Lindström, G; Moll, Michael; Taylor, G; Chilingarov, A G

    1995-01-01

    The damage induced by pions in silicon detectors is studied for positive and negative pions for fluence up to 10(14)cm-2 and 10(13) cm-2 respectively. Results on the energy dependence of the damage in the region of 65-330 MeV near to the  resonance are presented. The change in detector characteristics such as leakage current, charge collection efficiency and effective impurity concentration including long-term annealing effects have been studied. Comparisons to neutron and proton-induced damage are presented and discussed.

  15. Capture and transfer of pions in hydrogenous materials

    International Nuclear Information System (INIS)

    Armstrong, D.S.

    1990-05-01

    Pionic hydrogen is a short-lived exotic hydrogen isotope in which a negative pion replaces the atomic electron. The formation and subsequent interactions of pionic hydrogen are discussed, with emphasis on the process of pion transfer. Recent results using the pion charge-exchange reaction (π - , π 0 ) obtained at TRIUMF are reviewed. (Author) (35 refs., 3 tabs., 9 figs.)

  16. Is the quasielastic pion cross section really bigger than the pion-nucleus reaction cross section

    International Nuclear Information System (INIS)

    Silbar, R.R.

    1979-01-01

    It is shown that soft pion charge exchanges may increase the inclusive (π + ,π 0 ') cross section, relative to the total quasielastic (π + ,π + ') cross section, by as much as a factor of two. 4 references

  17. Status of PILAC: A pion linac facility for 1-GeV pion physics at LAMPF

    International Nuclear Information System (INIS)

    Thiessen, H.A.

    1990-01-01

    A Pion Linac (PILAC) is being designed for LAMPF. Together with its high resolution beam line and spectrometer, the system is optimized to provide 10 9 pions per second on target and 200-keV resolution for the (π + ,K + ) reaction at 920, MeV. There will also be an achromatic beam line capable of utilizing the maximum energy available, thus opening up the possibility of a broad experimental program as is being discussed at this workshop. 12 figs

  18. Pion-nucleus scattering in the isobar formalism

    International Nuclear Information System (INIS)

    Moniz, E.J.

    1978-06-01

    Lectures on the isobar-hole model for pion reactions include the isobar as an explicit degree of freedom and the connection with a purely pion and nucleon system, the formalism and its relation to the pion optical potential, the extended schematic model for pion scattering, a simple spinless s-wave model, application to pion-oxygen 16 scattering and comparison with elastic scattering data. In this way the extent is shown to which microscopic treatment of the many-body dynamics explains the data and the extent to which additional physical input is required. Another test is the various inelastic processes. Inclusive reactions are briefly discussed. 37 references

  19. Funny hills in pion spectra from heavy-ion collisions

    International Nuclear Information System (INIS)

    Rasmussen, J.O.

    1982-03-01

    A discussion of some of the systematic features of the pion spectra in heavy-ions reactions is given. A discussion of the hills and valleys in heavy ion pion spectra that show up at the lower pion energies is given. The following topics are discussed: (1) three kinds of funny hills; (2) π - / + ratios near center of mass; (3) new Monte Carlo studies of charged pion spectra; and (4) pion orbiting about fireballs and Bose-Einstein behavior as explanation for the mid-rapidity P/sub perpendicular to/ approx. = 0.4 to 0.5 m/sub π/c hill

  20. Knock out for subthreshold pion production

    International Nuclear Information System (INIS)

    Guet, C.; Prakash, M.

    1984-05-01

    The contribution of nucleon-nucleon-single collisions to subthreshold pion production in hadron-nucleus and nucleus-nucleus collisions, Esub(Lab) < 300 A MeV is investigated within a knock-out type model. This contribution might be important for energies higher than about 150 MeV/nucleon but decrease strongly with decreasing beam energy

  1. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Ebert, D.; Volkov, M.K.

    1981-01-01

    The pion polarizability is calculated in a chiral meson-quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Llanta and Tarrach is given. (orig.)

  2. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ehbert, D.

    1980-01-01

    The pion polarizability is calculated in a chiral meson-quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Lanta and Tarrach is given. The results of the paper give evidence to the nonlinear chiral Lagrangian favour

  3. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ehbert, D.

    1981-01-01

    The pion polarizability is calculated in a chiral meson- quark model at the one-loop level. The results are in complete agreement with earlier ones obtained within a chiral meson-baryon theory. A critical discussion of a recent paper by Llanta and Tarrach is given [ru

  4. Pion polarizability in a chiral quark model

    International Nuclear Information System (INIS)

    Volkov, M.K.; Ebert, D.

    1981-01-01

    It is shown that the pion polarizability calculated in a chiral model with quark loops agrees exactly with the analogous quantity found in a chiral meson-baryon model. The results of a paper by Llanta and Tarrach are discussed critically

  5. Role of vector mesons in pion electroproduction

    International Nuclear Information System (INIS)

    Uleshchenko, V.V.

    2007-01-01

    The talk is concerned with mechanisms of pion production in deeply inelastic scattering related to the interaction of virtual photon with the nucleon via an intermediate vector-meson state of the probe. A clear evidence of these mechanisms in the HERMES experimental data is revealed

  6. Pion absorption in excited nuclear matter

    International Nuclear Information System (INIS)

    Schmidt, H.R.; Albrecht, R.; Bock, R.; Gutbrod, H.H.; Kolb, B.W.; Lund, I.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Lee, I.Y.; Plasil, F.; Saini, S.; Tincknell, M.; Young, G.R.; Beckmann, P.; Berger, F.; Clewing, G.; Dragon, L.; Glasow, R.; Kampert, K.H.; Peitzmann, T.; Purschke, M.; Santo, R.; Claesson, G.; Eklund, A.; Garpman, S.; Gustafsson, H.A.; Idh, J.; Oskarsson, A.; Otterlund, I.; Persson, S.; Stenlund, E.; Franz, A.; Jacobs, P.; Poskanzer, A.M.; Ritter, H.G.; Kristiansson, P.; Loehner, H.; Obenshain, F.E.; Sorensen, S.P.; Siemiarczuk, T.

    1992-02-01

    The target dependence and azimuthal correlations of protons and plons are investigated for pA reactions at 4.9, 60 and 200 GeV. The experimental observations can be understood qualitatively under the assumption that pions are absorbed in excited target spectator matter. (orig.)

  7. Pion double charge exchange and hadron dynamics

    International Nuclear Information System (INIS)

    Johnson, M.B.

    1991-01-01

    This paper will review theoretical results to show how pion double charge exchange is contributing to our understanding of hadron dynamics in nuclei. The exploitation of the nucleus as a filter is shown to be essential in facilitating the comparison between theory and experiment. 23 refs., 3 figs., 2 tabs

  8. Study of giant resonances with pions

    International Nuclear Information System (INIS)

    Baer, H.W.

    1984-01-01

    Recent results on giant resonances obtained with pion-inelastic scattering and with single- and double-charge-exchange scattering are reviewed. The states discussed are isobaric analog states, double-isobaric analog states, and isovector L = 0, 1, and 2 collective states. 36 references

  9. The spin structure of the pion

    Energy Technology Data Exchange (ETDEWEB)

    Broemmel, D. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)]|[Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Diehl, M. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Goeckeler, M. [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)

    2007-08-15

    We present the first calculation of the transverse spin structure of the pion in lattice QCD. We find a characteristic asymmetry in the spatial distribution of transversely polarized quarks. This asymmetry is very similar in magnitude to the analogous asymmetry we previously obtained for quarks in the nucleon. Our results support the hypothesis that all Boer-Mulders functions are alike. (orig.)

  10. Exclusive electroproduction of two pions at HERA

    CERN Document Server

    Abramowicz, H.

    2012-01-25

    The exclusive electroproduction of two pions in the mass range 0.4 < M{\\pi}{\\pi} < 2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. The analysis was carried out in the kinematic range of 2 < Q2 < 80 GeV2, 32 < W < 180 GeV and |t| < 0.6 GeV2, where Q2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, |F(M{\\pi}{\\pi})|, assuming that the studied mass range includes the contributions of the {\\rho}, {\\rho}' and {\\rho}" vector-meson states. The masses and widths of the resonances were obtained and the Q2 dependence of the cross-section ratios {\\sigma}({\\rho}' \\rightarrow {\\pi}{\\pi})/{\\sigma}({\\rho}) and {\\sigma}({\\rho}" \\rightarrow {\\pi}{\\pi})/{\\sigma}({\\rho}) was extracted. The pion form factor obtained in the present analysis is compared to that obtained...

  11. Pion showers in highly granular calorimeters

    Indian Academy of Sciences (India)

    New results on properties of hadron showers created by pion beam at 8–80 GeV in high granular electromagnetic and hadron calorimeters are presented. Data were used for the first time to investigate the separation of the neutral and charged hadron showers. The result is important to verify the prediction of the PFA ...

  12. Physics with low energy pions and muons

    International Nuclear Information System (INIS)

    Konijn, J.

    1981-01-01

    This document is a collection of texts used for a course of lectures given by the author at the Technical University of Delft (NL) in 1981. It is therefore a comprehensive, Dutch language, review article starting with the discovery of pions and muons, describing their properties and finally discussing their applications in low energy physics. (C.F.)

  13. Nuclear potentials due to pion exchange

    International Nuclear Information System (INIS)

    Robillota, M.R.

    1984-01-01

    The two, three and four nucleon potentials due to the exchange of pions can be accurately calculated by means of chiral symmetry. The comparison of the dynamical content of these potentials allow us to understand the geometrical origin of the hierarchy existing among them. (Author) [pt

  14. Exclusive electroproduction of two pions at HERA

    International Nuclear Information System (INIS)

    Abramowicz, H.; Ashery, D.; Gueta, O.; Gurvich, E.; Ingbir, R.; Kananov, S.; Levy, A.; Stern, A.

    2012-01-01

    The exclusive electroproduction of two pions in the mass range 0.4 ππ -1 . The analysis was carried out in the kinematic range of 2 2 2 , 32 2 , where Q 2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, vertical stroke F(M ππ ) vertical stroke, assuming that the studied mass range includes the contributions of the ρ, ρ' and ρ'' vector-meson states. The masses and widths of the resonances were obtained and the Q 2 dependence of the cross-section ratios σ(ρ'→ππ)/ σ(ρ) and σ(ρ''→ππ)/ σ(ρ) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e + e - →π + π - . (orig.)

  15. Pion electromagnetic mass difference in QCD

    International Nuclear Information System (INIS)

    Margvelashvili, M.V.

    1989-01-01

    The results of currents algebra and the theory of partial conservation of axial currents the sum rules for the calculation of electromagnetic pion mass difference are developed. The procedure applied is suitable for other physical applications as it permits to calculate the integrals from different correlators with the assigned weight functions

  16. Photoproduction of neutral pions off protons

    NARCIS (Netherlands)

    Crede, V.; Sparks, N.; Wilson, A.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, R.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, Chr; Gregor, R.; Gridnev, A.; Gutz, E.; Hillert, W.; Hoffmeister, P.; Jaegle, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Klein, Frank; Klein, Friedrich; Klempt, E.; Kotulla, M.; Krusche, B.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nanova, M.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S.; Sokhoyan, V.; Suele, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, Ch

    2011-01-01

    Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction gamma p -> p pi(0) for photon energies between 0.85 and 2.50 GeV. The pi(0) mesons are observed in their dominant neutral decay mode: pi(0) -> gamma gamma. For the first time, the differential cross

  17. Pion-pair production by two photons

    International Nuclear Information System (INIS)

    Terazawa, Hidezumi.

    1994-07-01

    The cross section for pion-pair production by two photons is calculated approximately by using the low energy theorem previously derived from partially-conserved-axial-vector-current hypothesis and current algebra, and found to agree very well with the experimental data recently obtained by the Mark II, TPC/Two-Gamma and CLEO Collaborations. (author)

  18. Measurement of the Charged-Pion Polarizability

    CERN Document Server

    Adolph, C.; Alexeev, M.G.; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Badelek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Buchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S.U.; Cicuttin, A.; Colantoni, M.; Crespo, M.L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O.Yu.; Dinkelbach, A.M.; Donskov, S.V.; Doshita, N.; Duic, V.; Dunnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M., Jr.; Fischer, H.; Franco, C.; von Hohenesche, N. du Fresne; Friedrich, J.M.; Frolov, V.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Geyer, R.; Gnesi, I.; Gobbo, B.; Goertz, S.; Gorzellik, M.; Grabmuller, S.; Grasso, A.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Guthorl, T.; Haas, F.; von Harrach, D.; Hahne, D.; Hashimoto, R.; Heinsius, F.H.; Herrmann, F.; Hinterberger, F.; Hoppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Jorg, P.; Joosten, R.; Kabuss, E.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Konigsmann, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.; Kramer, M.; Kroumchtein, Z.V.; Kuchinski, N.; Kuhn, R.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Lednev, A.A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G.K.; Marchand, C.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Moinester, M.A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V.I.; Novy, J.; Nowak, W.D.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peshekhonov, D.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Rocco, E.; Rossiyskaya, N.S.; Ryabchikov, D.I.; Rychter, A.; Samoylenko, V.D.; Sandacz, A.; Sarkar, S.; Savin, I.A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schluter, T.; Schmidt, K.; Schmieden, H.; Schonning, K.; Schopferer, S.; Schott, M.; Shevchenko, O.Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Wolbeek, J. ter; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Virius, M.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

    2015-02-10

    The COMPASS collaboration at CERN has investigated pion Compton scattering, $\\pi^-\\gamma\\rightarrow \\pi^-\\gamma$, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction $\\pi^-\\mathrm{Ni}\\rightarrow\\pi^-\\gamma\\;\\mathrm{Ni}$, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, $Q^2<0.0015$ (GeV/$c$)$^2$. From a sample of 63 000 events the pion electric polarisability is determined to be $\\alpha_\\pi = (2.0 \\pm 0.6_{\\mbox{stat}} \\pm 0.7_{\\mbox{syst}}) \\times 10^{-4} \\mbox{fm}^3$ under the assumption $\\alpha_\\pi=-\\beta_\\pi$, which relates the electric and magnetic dipole polarisabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction, that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is fou...

  19. Investigation of pion-nucleus interactions

    International Nuclear Information System (INIS)

    Moore, C.F.

    1992-09-01

    This report summarizes the work carried out by personnel from the University of Texas at Austin at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF). The research activities involved experiments done with the Energetic Pion Channel and Spectrometer (EPICS), the Low Energy Pion Channel (LEP), the Pion and Particle Physics Channel (P 3 ), the High Resolution Spectrometer (HRS), and planning a new experimental program associated with the new high-resolution Neutral Meson Spectrometer (NMS) at LAMPF. A brief overview of work supported by this grant is given followed by an account of the study of the double giant resonances in pion double charge exchange on 51 V, 115 In, and 197 Au. This report contains a list of published papers and preprints, abstracts, and invited talks. These papers summarize experiments involving participants supported by this grant and indicate the work accomplished by these participants in this program of medium energy nuclear physics research. Lists of the most recent proposals on which we have participation at LAMPF, proposals which have been approved this past year to run as experiments, personnel who have participated in this research program are included. The research cited in this report is, in many cases, the collaborative effort of many groups associated with research at LAMPF

  20. Pion photoproduction in nucleons at low energies

    International Nuclear Information System (INIS)

    Carvalho, F.A.B.R. de.

    1983-01-01

    A new semiphenomenological analysis of the multipoles for pion photoproduction from nucleons, in the region of the first π-N resonance is presented. Through an energy dependent model, multipoles with isospin 1/2 and 3/2 and total angular momentum J [pt

  1. Low energy scattering with a nontrivial pion

    International Nuclear Information System (INIS)

    Fariborz, Amir H.; Jora, Renata; Schechter, Joseph

    2007-01-01

    An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion-pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark field. Here we turn on the pion mass and note that the current algebra formula no longer holds exactly. We discuss this small deviation and also study the effects of a SU(3) symmetric quark mass type term on the masses and mixings of the eight SU(3) multiplets in the model. We calculate the s-wave scattering lengths, including the beyond current algebra theorem corrections due to the scalar mesons, and observe that the effect of the scalar mesons is to improve the agreement with experiment. In the process, we uncover the way in which linear sigma models give controlled corrections (due to the presence of scalar mesons) to the current algebra scattering formula. Such a feature is commonly thought to exist only in the nonlinear sigma model approach

  2. Exclusive electroproduction of two pions at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (PL). Faculty of Physics and Applied Computer Science] (and others)

    2011-11-15

    The exclusive electroproduction of two pions in the mass range 0.4< M{sub {pi}}{sub {pi}} <2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb{sup -1}. The analysis was carried out in the kinematic range of 2< Q{sup 2}<80 GeV{sup 2}, 32pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, vertical stroke F(M{sub {pi}}{sub {pi}}) vertical stroke, assuming that the studied mass range includes the contributions of the {rho}, {rho}{sup '} and {rho}'' vector-meson states. The masses and widths of the resonances were obtained and the Q{sup 2} dependence of the cross-section ratios {sigma}({rho}{sup '} {yields} {pi}{pi})/{sigma}({rho}) and {sigma}({rho}'' {yields} {pi}{pi})/{sigma}({rho}) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -}. (orig.)

  3. Effects of pions on normal tissues

    International Nuclear Information System (INIS)

    Tokita, N.

    1981-01-01

    Verification of the uniform biological effectiveness of pion beams of various dimensions produced at LAMPF has been made using cultured mammalian cells and mouse jejunum. Normal tissue radiobiology studies at LAMPF are reviewed with regard to biological beam characterization for the therapy program and the current status of acute and late effect studies on rodents

  4. Effects of the pion string at heavy ion collisions

    CERN Document Server

    Mao, Hong

    2005-01-01

    We study the possible signals of the pion string associated with the QCD chiral phase transition in LHC Pb-Pb collision at energy square root s=5.5 TeV. We follow the Kibble-Zurek mechanism to discuss the production and evolution of the pion string. We will show that if the QCD chiral phase transition really takes place in the LHC Pb-Pb collision process and the phase transition is in the second order, the pion string will be inevitably produced and subsequently decay. The main effect of this phenomenon is that there is a generation of a large number of pions in the final state produced by the decay of the pion string, and these pions are mostly distributed in a low momentum region with p143 MeV; also there are lots of neutral pions distributed in a low momentum region with the mean momentum at p21 Me V.

  5. Precision determination of pion mass using X-ray CCD spectroscopy

    CERN Document Server

    Nelms, N; Augsburger, M A; Borchert, G; Chatellard, D; Daum, M; Egger, J P; Gotta, D; Hauser, P; Indelicato, P J; Jeannet, E; Kirch, K; Schult, O W B; Siems, T; Simons, L M; Wells, A

    2002-01-01

    An experiment is described which aims to determine the charged pion mass to 1 ppm or better, from which a new determination of the upper limit of the muon neutrino mass is anticipated. The experimental approach uses a high-intensity negative pion beam (produced at the PSI 590 MeV proton cyclotron), injected into a cyclotron trap and stopped inside a gas-filled target chamber, to form highly excited exotic atoms of pionic nitrogen and muonic oxygen. The energy of photons, emitted during de-excitation, is directly proportional to the mass of the pion or muon. These soft X-ray emission spectra are measured using a high-precision crystal spectrometer, with an array of six, high quantum efficiency X-ray position resolving CCDs at the focus. To achieve sub-ppm accuracy, simultaneous calibration of the pionic nitrogen line is provided by measurement of an adjacent muonic oxygen line, whose energy is known to 0.3 ppm. The high precision of the experiment offers a new opportunity to determine the pion mass to the leve...

  6. The pion: an enigma within the Standard Model

    Energy Technology Data Exchange (ETDEWEB)

    Horn, Tanja; Roberts, Craig D.

    2016-05-27

    Almost 50 years after the discovery of gluons & quarks, we are only just beginning to understand how QCD builds the basic bricks for nuclei: neutrons, protons, and the pions that bind them. QCD is characterised by two emergent phenomena: confinement & dynamical chiral symmetry breaking (DCSB). They are expressed with great force in the character of the pion. In turn, pion properties suggest that confinement & DCSB are closely connected. As both a Nambu-Goldstone boson and a quark-antiquark bound-state, the pion is unique in Nature. Developing an understanding of its properties is thus critical to revealing basic features of the Standard Model. We describe experimental progress in this direction, made using electromagnetic probes, highlighting both improvements in the precision of charged-pion form factor data, achieved in the past decade, and new results on the neutral-pion transition form factor. Both challenge existing notions of pion structure. We also provide a theoretical context for these empirical advances, first explaining how DCSB works to guarantee that the pion is unnaturally light; but also, nevertheless, ensures the pion is key to revealing the mechanisms that generate nearly all the mass of hadrons. Our discussion unifies the charged-pion elastic and neutral-pion transition form factors, and the pion's twist-2 parton distribution amplitude. It also indicates how studies of the charged-kaon form factor can provide significant contributions. Importantly, recent predictions for the large-$Q^2$ behaviour of the pion form factor can be tested by experiments planned at JLab 12. Those experiments will extend precise charged-pion form factor data to momenta that can potentially serve in validating factorisation theorems in QCD, exposing the transition between the nonperturbative and perturbative domains, and thereby reaching a goal that has long driven hadro-particle physics.

  7. Study on the interference correlations between the pions in the K-p interactions at 32 GeV/c

    International Nuclear Information System (INIS)

    Babintsev, V.V.; Bryzgalov, V.V.; Bryukhanova, T.M.; Levitski, M.S.; Moiseev, A.M.; Patalakha, D.I.; Proskuryakov, A.S.

    1981-01-01

    Interference effects between identical pions in K - p interactions at 32 GeV/c are studied. Positive short-range interference correlations have been found in both π + π + and π - π - systems. It is shown that the background noise, calculated using the π + π - pairs produced in the same event, essentially affect the magnitude and the shape of the effect. With more correct determination of the background noise the transverse radius of the pion emission range is estimated to be Rsub(T) approximately 2 Fm [ru

  8. Pion source parameters in heavy ion collisions

    International Nuclear Information System (INIS)

    Crowe, K.M.; Bistirlich, J.A.; Bossingham, R.R.

    1984-12-01

    Following the early work of Goldhaber, Lee, and Pais, many experiments have used the momentum correlations between identical bosons to determine the space-time extent of the pion source for various reactions between elementary hadrons. This technique, known as intensity interferometry, has recently been applied to nuclear collisions at both intermediate and very high energies. Here we report on measurements of the radius and lifetime of the pion source in the reactions 1.8 A GeV 40 Ar + KCl → 2π/sup +-/ + X, 1.8 A GeV 20 Na + NaF → 2π - + X, and 1.71 A GeV 56 Fe + Fe → 2π - + X. 11 references

  9. Pion and kaon freezeout in NA44

    International Nuclear Information System (INIS)

    1994-01-01

    The NA44 spectrometer is optimized for the study of single and two-particle particle spectra near mid-rapidity for transverse momenta below ∼ 1 GeV/c. A large fraction of all pairs in the spectrometer's acceptance are at low relative momenta, resulting in small statistical uncertainties on the extracted size parameters. In addition, the spectrometer's clean particle identification allows the authors to measure correlation functions for pions, kaons, and protons. This contribution will concentrate on the source size parameters determined from pion and kaon correlation functions. These size parameters will be compared to calculations from the RQMD event generator and also interpreted in the context of a hydrodynamic model. Finally, the measured single particle spectra will be examined from the viewpoint of hydrodynamics

  10. Low-energy pion-nucleon scattering

    International Nuclear Information System (INIS)

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-01-01

    An analysis of low-energy charged pion-nucleon data from recent π ± p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f 2 =0.0756±0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P 31 and P 13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided. copyright 1998 The American Physical Society

  11. Pion contamination in the MICE muon beam

    International Nuclear Information System (INIS)

    Adams, D.; Barclay, P.; Bayliss, V.; Brashaw, T.W.; Alekou, A.; Apollonio, M.; Barber, G.; Asfandiyarov, R.; Blondel, A.; De Bari, A.; Bayes, R.; Bertoni, R.; Bonesini, M.; Blackmore, V.J.; Blot, S.; Bogomilov, M.; Booth, C.N.; Bowring, D.; Boyd, S.; Bravar, U.

    2016-01-01

    The international Muon Ionization Cooling Experiment (MICE) will perform a systematic investigation of ionization cooling with muon beams of momentum between 140 and 240 MeV/c at the Rutherford Appleton Laboratory ISIS facility. The measurement of ionization cooling in MICE relies on the selection of a pure sample of muons that traverse the experiment. To make this selection, the MICE Muon Beam is designed to deliver a beam of muons with less than ∼1% contamination. To make the final muon selection, MICE employs a particle-identification (PID) system upstream and downstream of the cooling cell. The PID system includes time-of-flight hodoscopes, threshold-Cherenkov counters and calorimetry. The upper limit for the pion contamination measured in this paper is f π  < 1.4% at 90% C.L., including systematic uncertainties. Therefore, the MICE Muon Beam is able to meet the stringent pion-contamination requirements of the study of ionization cooling

  12. Pion contamination in the MICE muon beam

    CERN Document Server

    Bogomilov, M.; Vankova-Kirilova, G.; Bertoni, R.; Bonesini, M.; Chignoli, F.; Mazza, R.; Palladino, V.; de Bari, A.; Cecchet, G.; Capponi, M.; Iaciofano, A.; Orestano, D.; Pastore, F.; Tortora, L.; Kuno, Y.; Sakamoto, H.; Ishimoto, S.; Japan, Ibaraki; Filthaut, F.; Hansen, O.M.; Ramberger, S.; Vretenar, M.; Asfandiyarov, R.; Blondel, A.; Drielsma, F.; Karadzhov, Y.; Charnley, G.; Collomb, N.; Gallagher, A.; Grant, A.; Griffiths, S.; Hartnett, T.; Martlew, B.; Moss, A.; Muir, A.; Mullacrane, I.; Oates, A.; Owens, P.; Stokes, G.; Warburton, P.; White, C.; Adams, D.; Barclay, P.; Bayliss, V.; Bradshaw, T.W.; Courthold, M.; Francis, V.; Fry, L.; Hayler, T.; Hills, M.; Lintern, A.; Macwaters, C.; Nichols, A.; Preece, R.; Ricciardi, S.; Rogers, C.; Stanley, T.; Tarrant, J.; Watson, S.; Wilson, A.; Bayes, R.; Nugent, J.C.; Soler, F.J.P.; Cooke, P.; Gamet, R.; Alekou, A.; Apollonio, M.; Barber, G.; Colling, D.; Dobbs, A.; Dornan, P.; Hunt, C.; Lagrange, J-B.; Long, K.; Martyniak, J.; Middleton, S.; Pasternak, J.; Santos, E.; Savidge, T.; Uchida, M.A.; Blackmore, V.J.; Carlisle, T.; Cobb, J.H.; Lau, W.; Rayner, M.A.; Tunnell, C.D.; Booth, C.N.; Hodgson, P.; Langlands, J.; Nicholson, R.; Overton, E.; Robinson, M.; Smith, P.J.; Dick, A.; Ronald, K.; Speirs, D.; Whyte, C.G.; Young, A.; Boyd, S.; Franchini, P.; Greis, J.R.; Pidcott, C.; Taylor, I.; Gardener, R.; Kyberd, P.; Littlefield, M.; Nebrensky, J.J.; Bross, A.D.; Fitzpatrick, T.; Leonova, M.; Moretti, A.; Neuffer, D.; Popovic, M.; Rubinov, P.; Rucinski, R.; Roberts, T.J.; Bowring, D.; DeMello, A.; Gourlay, S.; Li, D.; Prestemon, S.; Virostek, S.; Zisman, M.; Drews, M.; Hanlet, P.; Kafka, G.; Kaplan, D.M.; Rajaram, D.; Snopok, P.; Torun, Y.; Winter, M.; Blot, S.; Kim, Y.K.; Bravar, U.; Onel, Y.; Cremaldi, L.M.; Hart, T.L.; Luo, T.; Sanders, D.A.; Summers, D.J.; Cline, D.; Yang, X.; Coney, L.; Hanson, G.G.; Heidt, C.

    2016-01-01

    The international Muon Ionization Cooling Experiment (MICE) will perform a systematic investigation of ionization cooling with muon beams of momentum between 140 and 240\\,MeV/c at the Rutherford Appleton Laboratory ISIS facility. The measurement of ionization cooling in MICE relies on the selection of a pure sample of muons that traverse the experiment. To make this selection, the MICE Muon Beam is designed to deliver a beam of muons with less than $\\sim$1\\% contamination. To make the final muon selection, MICE employs a particle-identification (PID) system upstream and downstream of the cooling cell. The PID system includes time-of-flight hodoscopes, threshold-Cherenkov counters and calorimetry. The upper limit for the pion contamination measured in this paper is $f_\\pi < 1.4\\%$ at 90\\% C.L., including systematic uncertainties. Therefore, the MICE Muon Beam is able to meet the stringent pion-contamination requirements of the study of ionization cooling.

  13. Pion interactions at medium energies: Progress report

    International Nuclear Information System (INIS)

    Allred, J.C.; Goodman, C.

    1970-01-01

    Accelerating equipment, radiation detectors, and data acquisition equipment are described for a proposed study of 300 MeV pion scattering on deuterium targets at the Space Radiation Effects Laboratory in Newport News, Virginia. A key concept in the proposed program of measurements is a proposal by G.C Phillips to develop planes of proportional counters compatible with fast scintillation logic from pre-existing counters. The impetus for the research is the eventual use of the LAMPF accelerator at Los Alamos

  14. Isospin violation in pion-kaon scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, Bastian E-mail: b.kubis@fz-juelich.de; Meissner, Ulf-G. E-mail: ulf-g.meissner@fz-juelich.de

    2002-03-11

    We consider strong and electromagnetic isospin violation in near-threshold pion-kaon scattering. At tree level, such effects are small for all physical channels. We work out the complete one-loop corrections to the process {pi}{sup -}K{sup +}{yields}{pi}{sup 0}K{sup 0}. They come out rather small. We also show that the corresponding radiative cross section is highly suppressed at threshold.

  15. Isospin violation in pion-kaon scattering

    International Nuclear Information System (INIS)

    Kubis, Bastian; Meissner, Ulf-G.

    2002-01-01

    We consider strong and electromagnetic isospin violation in near-threshold pion-kaon scattering. At tree level, such effects are small for all physical channels. We work out the complete one-loop corrections to the process π - K + →π 0 K 0 . They come out rather small. We also show that the corresponding radiative cross section is highly suppressed at threshold

  16. Visual sensations induced by relativistic pions

    International Nuclear Information System (INIS)

    McNulty, P.J.; Pease, V.P.; Bond, V.P.

    1976-01-01

    Visual sensations were experienced when bursts of high-energy pions passed through the dark-adapted right eyes of three human subjects. The threshold for a visual sensation was typically 1 to 3 μrad at the retina. Data are presented to show that the mechanism is Cerenkov radiation generated within the vitreous humor. Threshold measurements agree with published optical data. A comparison is made between our observations and the light flashes observed in deep space by Apollo astronauts

  17. Weak pion production off the nucleon

    International Nuclear Information System (INIS)

    Hernandez, E.; Nieves, J.; Valverde, M.

    2007-01-01

    We develop a model for the weak pion production off the nucleon, which besides the delta pole mechanism [weak excitation of the Δ(1232) resonance and its subsequent decay into Nπ], includes also some background terms required by chiral symmetry. We refit the C 5 A (q 2 ) form factor to the flux-averaged ν μ p→μ - pπ + ANL q 2 -differential cross section data, finding a substantially smaller contribution of the delta pole mechanism than traditionally assumed in the literature. Within this scheme, we calculate several differential and integrated cross sections, including pion angular distributions, induced by neutrinos and antineutrinos and driven both by charged and neutral currents. In all cases we find that the background terms produce quite significant effects, and that they lead to an overall improved description of the data, as compared to the case where only the delta pole mechanism is considered. We also show that the interference between the delta pole and the background terms produces parity-violating contributions to the pion angular differential cross section, which are intimately linked to T-odd correlations in the contraction between the leptonic and hadronic tensors. However, these latter correlations do not imply a genuine violation of time-reversal invariance because of the existence of strong final state interaction effects

  18. Biomedical applications of pion-producing accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, L [Los Alamos Scientific Lab., NM (USA)

    1980-01-01

    It was proved by the Los Alamos Scientific Laboratory of the U. S. that applications of pi-mesons in the treatment of cancer could eliminate the problem of dose localization attendant upon conventional radiation therapy. A negative pi-meson, once it is produced from energy, behaves quantum mechanically like an electron and executes orbits around a nucleus. Because its mass is 300 times that of an electron, the orbits are smaller in that ratio. Hence, on achieving the innermost orbit, the pi-meson is captured by the nucleus and causes it to explode. The resultant nuclear shrapnel travel very short distances, about 1 mm on the average, and are very effective in rendering afflicted cells non-productive without causing any damages to healthy cells in the vicinity of the tumor. Given pion therapy, over 100 patients showed encouraging results. The laboratory, sponsored by the National Cancer Institute, is now developing a small facility for pion therapy. Tests on the critical components of the pion generator are expected to be conducted within the next 12 - 16 months.

  19. Pion production in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Norbury, J.W.

    1983-01-01

    A Lorentz-invariant differential cross section for pion production in peripheral, relativistic, heavy ion collisions is calculated for the collisions of an 16 O projectile onto a 12 C target. The pions are produced via excitations of a Δ(3,3) resonant state in the projectile with simultaneous excitation of an M1 giant resonance in the target. A second order amplitude describing resonance formation and decay is derived within the context of second order, time-dependent perturbation theory and a corresponding transition rate is evaluated. This is then applied to the problem of pion production and a differential cross section is calculated using a simple product-of-states model. The whole theory is then re-formulated within a second quantized particle-hole model which describes the basic process of M1 giant resonance formation as well as the formation and decay of the intermediate Δ(3,3) resonance. Subsequently, a new Lorentz-invariant differential cross section is calculated from the particle-hole amplitude. The theoretical cross section is compared with some experimental data and the agreement is found to be satisfactory given the nature of the data and the assumptions of the theory

  20. Coherent detectors

    International Nuclear Information System (INIS)

    Lawrence, C R; Church, S; Gaier, T; Lai, R; Ruf, C; Wollack, E

    2009-01-01

    Coherent systems offer significant advantages in simplicity, testability, control of systematics, and cost. Although quantum noise sets the fundamental limit to their performance at high frequencies, recent breakthroughs suggest that near-quantum-limited noise up to 150 or even 200 GHz could be realized within a few years. If the demands of component separation can be met with frequencies below 200 GHz, coherent systems will be strong competitors for a space CMB polarization mission. The rapid development of digital correlator capability now makes space interferometers with many hundreds of elements possible. Given the advantages of coherent interferometers in suppressing systematic effects, such systems deserve serious study.

  1. Coherent detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, C R [M/C 169-327, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Church, S [Room 324 Varian Physics Bldg, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States); Gaier, T [M/C 168-314, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Lai, R [Northrop Grumman Corporation, Redondo Beach, CA 90278 (United States); Ruf, C [1533 Space Research Building, The University of Michigan, Ann Arbor, MI 48109-2143 (United States); Wollack, E, E-mail: charles.lawrence@jpl.nasa.go [NASA/GSFC, Code 665, Observational Cosmology Laboratory, Greenbelt, MD 20771 (United States)

    2009-03-01

    Coherent systems offer significant advantages in simplicity, testability, control of systematics, and cost. Although quantum noise sets the fundamental limit to their performance at high frequencies, recent breakthroughs suggest that near-quantum-limited noise up to 150 or even 200 GHz could be realized within a few years. If the demands of component separation can be met with frequencies below 200 GHz, coherent systems will be strong competitors for a space CMB polarization mission. The rapid development of digital correlator capability now makes space interferometers with many hundreds of elements possible. Given the advantages of coherent interferometers in suppressing systematic effects, such systems deserve serious study.

  2. Measurement of the charged-pion polarisability at COMPASS

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    For more than a decade, COMPASS has been tackling the measurement of the electromagnetic polarizability of the charged pion, which describes the stiffness of the pion against deformation in electromagnetic fields. Previous experiments date back to the 1980's in Serpukhov (Russia), where the Primakoff method for realizing interactions of charged pions with quasi-real photons was first employed. Later also other techniques in photon-nucleon and photon-photon collisions were carried out at different machines. The COMPASS measurement demonstrates that the charged-pion polarizability is significantly smaller than the previous results, roughly by a factor two, with the smallest uncertainties realized so far. The pion polarisability is of fundamental interest in the low-energy sector of quantum chromodynamics. It is directly linked to the quark-gluon substructure and dynamics of the pion, the lightest bound system of strong interaction.

  3. Low energy pion detection by a silicon surface barrier telescope

    International Nuclear Information System (INIS)

    Sealock, R.M.; Caplan, H.S.; Leung, M.K.

    1978-01-01

    Four telescopes of three (2-ΔE, 1-E) silicon surface barrier detectors each, mounted in the focal plane of a magnetic spectrometer, have been used to detect positive pions in the energy range from 4.7-17.9 MeV and negative pions from 14.1-17.9 MeV. Positive pions from 4.7-12.7 MeV were stopped in the third detector while positive and negative pions from 14.1-17.9 MeV were detected in transmission. For energies greater than 7.4 MeV aluminum moderators were placed in front of the first detector to degrade the pion energy. Energy spectra show well resolved pion peaks with extremely low background. Double differential cross sections for the 12 C(e,π + ) 12 B,e' reaction have been measured. (Auth.)

  4. Covariant density functional theory: The role of the pion

    International Nuclear Information System (INIS)

    Lalazissis, G. A.; Karatzikos, S.; Serra, M.; Otsuka, T.; Ring, P.

    2009-01-01

    We investigate the role of the pion in covariant density functional theory. Starting from conventional relativistic mean field (RMF) theory with a nonlinear coupling of the σ meson and without exchange terms we add pions with a pseudovector coupling to the nucleons in relativistic Hartree-Fock approximation. In order to take into account the change of the pion field in the nuclear medium the effective coupling constant of the pion is treated as a free parameter. It is found that the inclusion of the pion to this sort of density functionals does not destroy the overall description of the bulk properties by RMF. On the other hand, the noncentral contribution of the pion (tensor coupling) does have effects on single particle energies and on binding energies of certain nuclei.

  5. Mechanisms for pion production in heavy ion collisions

    International Nuclear Information System (INIS)

    Pfeiffer, M.

    1991-01-01

    In the following contribution some aspects concerning pion production in heavy ion collisions will be discussed. After a general introduction the properties of pions and the Δ-resonance will be briefly mentioned. In the following section some points refering to the pion production in a relativistic heavy ion collision will be discussed. In addition, the basic ideas of the applied models will be shown. In the last part results from existing experiments and possible interpretations will be presented. (orig.)

  6. [Measurements of observables of pion-nucleon reactions]. Progress report

    International Nuclear Information System (INIS)

    Sadler, M.E.

    1985-01-01

    This document reports the progress of the research of pion reactions. These include (1) a study to measure observables in the pion-nucleon system in the momentum interval 400 to 700 MeV/c, (2) differential cross section measurements at low energy for pion-nucleon charge exchange, and (3) elastic and inelastic scattering of π +- on 3 H and 3 He. Individual experiments will be indexed separately

  7. A possible form of the pion's structure function

    International Nuclear Information System (INIS)

    Long Ming; Huang Tao

    1986-01-01

    The pion's structure function behaviour is discussed by using the Fock state expansion of the hadronic wave function in QCD in this paper. As an example, we employ a model wave function of the Fock state in the light-cone and assume a Regge behaviour of a weight function for higher Fock states, and we get a possible form of the pion's structure function. This form is consistent with experimental data of the pion's structure function

  8. Pion broadening and low-mass dilepton production

    International Nuclear Information System (INIS)

    Schulze, H.-J.; Blaschke, D.

    2002-01-01

    Mass and transverse momentum spectra of dileptons produced in Pb + Au (158 GeV/u) collisions within a pion annihilation model are determined. A fit to the data requires simultaneous mass reduction and broadening of the in-medium rho propagator. The introduction of a finite pion width, as required within self-consistent approaches to the interacting pion gas, further improves the agreement with the data

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

    International Nuclear Information System (INIS)

    Ginocchio, J.N.

    1988-01-01

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

  10. Soft and hard contributions to hard pion photoproduction

    International Nuclear Information System (INIS)

    Afanasev, Andrei; Carlson, Carl E.; Wahlquist, Christian

    2000-01-01

    Pion photoproduction at high transverse momentum supplements what can be learned in the standard probes of deep inelastic scattering and Drell-Yan processes. With polarized initial states there is sensitivity to the polarized gluon distribution, Δg, in leading order. This contrasts to other processes mentioned, which have no leading order gluon contribution. Additionally, in some kinematic regions the process occurs mainly due to pion production at short distances ('direct pion production', resulting in kinematically isolated pions), which gives sensitivity to the high-x valence quark distribution

  11. Design and simulation of the nuSTORM pion beamline

    Energy Technology Data Exchange (ETDEWEB)

    Liu, A., E-mail: aoliu@fnal.gov; Neuffer, D.; Bross, A.

    2015-11-21

    The nuSTORM (neutrinos from STORed Muons) proposal presents a detailed design for a neutrino facility based on a muon storage ring, with muon decay in the production straight section of the ring providing well defined neutrino beams. The facility includes a primary high-energy proton beam line, a target station with pion production and collection, and a pion beamline for pion transportation and injection into a muon decay ring. The nuSTORM design uses “stochastic injection”, in which pions are directed by a chicane, referred to as the Orbit Combination Section (OCS), into the production straight section of the storage ring. Pions that decay within that straight section provide muons within the circulating acceptance of the ring. The design enables injection without kickers or a separate pion decay transport line. The beam line that the pions traverse before being extracted from the decay ring is referred to as the pion beamline. This paper describes the design and simulation of the pion beamline, and includes full beam dynamics simulations of the system.

  12. Multi-nucleon pion absorption in the 4He(π+,ppp)n reaction

    International Nuclear Information System (INIS)

    Weber, P.; McAlister, J.; Olszewski, R.; Feltham, A.; Hanna, M.; Johnson, R.R.; Pavan, M.; Ponting, C.; Rozon, F.M.; Sevior, M.; Sossi, V.; Vetterli, D.; Humphrey, D.; Lolos, G.J.; Papandreou, Z.; Tacik, R.; Ottewell, D.; Sheffer, G.; Smith, G.R.; Mardor, Y.; May-Tal, S.

    1990-08-01

    Three-proton emission cross sections for the 4 He(π + ,ppp)n reaction were measured at an incident pion kinetic energy of T pi + =165 MeV over a wide angular range in a kinematically complete experiment. Angular correlations, missing momentum distributions and energy spectra are compared with three- and four-body phase space Monte Carlo calculations. The results provide strong evidence that most of the three-proton coincidences result from three-nucleon absorption. From phase-space integration the total three-nucleon absorption cross section is estimated to be σ 3N =4.8 ± 1.0 mb. The cross section involving four nucleons is small and is estimated to be σ 4N 4 He, multi-nucleon pion absorption seems to represent only a small fraction. (Author) (40 refs., 3 tabs., 15 figs.)

  13. Measurement of the charged pion mass using a low-density target of light atoms

    Directory of Open Access Journals (Sweden)

    Trassinelli M.

    2016-01-01

    Full Text Available We present a new evaluation of the negatively charged pion mass based on the simultaneous spectroscopy of pionic nitrogen and muonic oxygen transitions using a gaseous target composed by a N2/O2 mixture at 1.4 bar. We present the experimental set-up and the methods for deriving the pion mass value from the spatial separation from the 5g − 4f πN transition line and the 5g − 4f μO transition line used as reference. Moreover, we discuss the importance to use dilute targets in order to minimize the influence of additional spectral lines from the presence of remaining electrons during the radiative emission. The occurrence of possible satellite lines is investigated via hypothesis testing methods using the Bayes factor.

  14. Simulation of CO and NO emissions in a SI engine using a 0D coherent flame model coupled with a tabulated chemistry approach

    International Nuclear Information System (INIS)

    Bougrine, S.; Richard, S.; Michel, J.-B.; Veynante, D.

    2014-01-01

    Highlights: • A new 0D combustion model (CFM1D-TC) based on a tabulation approach is proposed. • Complex chemistry calculations are used to deduce composition and relaxation times. • NO and CO exponentially relax from a perturbed state to the equilibrium state. • The new model is implemented in an engine simulation software. • Validations are performed by comparison with a wide range of experimental data. - Abstract: Environmental issues stimulate the elaboration of new powertrain systems and fuels for transport as an essential priority to decrease air pollution and green house gases emissions. Developments ranging from architecture definition to engine control and calibration are today increasingly performed using complete vehicle simulators running close to real times. The challenge for engineers is therefore to develop models able to accurately reproduce the engine response without altering the CPU efficiency of the simulator. For this purpose, 0-dimensional models are commonly used to describe combustion processes in engine combustion chambers. This paper extends a 0-dimensional coherent flame model (CFM), called CFM1D, to incorporate chemical effects related to the fuel composition and thermodynamic conditions at low computational costs. Improvements are carried out integrating the NO relaxation approach (NORA) based on a priori homogeneous reactor computations and initially developed for 3D simulations to describe post-oxidation processes in the burnt gases. In this work, this method is extended to the modeling of CO production and oxidation leading to the CORA (CO Relaxation Approach) model. Both NO and CO reaction rates are therefore written as linear relaxations towards their equilibrium mass fraction values Y k eq (where k stands for NO or CO) within a characteristic time τ k . In this approach, Y k eq and τ k are tabulated as functions of equivalence ratio, fresh gases dilution rate by burnt gases, pressure and enthalpy. The resulting new

  15. Coherent generation of mesons in nucleon-nucleon interactions

    CERN Document Server

    Takibaev, Z S; Zaitsev, K G

    1974-01-01

    The authors have at an experiment conducted at CERN searched for events of 0 four-prong type which satisfy coherent pion production. The 2-meter hydrogen bubble chamber at CERN was bombarded by 19.07 GeV protons. The cross-section for four final state particle events was 13.04 mb. the cross-section for the process pp to pp pi /sup +/ pi /sup -/ was 1.1 mb and the cross section for coherent pion production was found to vary according to the criteria used between 0.044 mb. and 0.2 mb. Some theoretical work is given using the Glauber formalism in which it is assumed that the nucleon behaves like a nucleus and contains sub-particles. From the theory and data an upper limit of 10 is put on the number of subparticles in the nucleon. (9 refs).

  16. Rare kaon, muon, and pion decay

    International Nuclear Information System (INIS)

    Littenberg, L.

    1998-01-01

    The author discusses the status of and prospects for the study of rare decays of kaons, muons, and pions. Studies of rare kaon decays are entering an interesting new phase wherein they can deliver important short-distance information. It should be possible to construct an alternative unitarity triangle to that determined in the B sector, and thus perform a critical check of the Standard Model by comparing the two. Rare muon decays are beginning to constrain supersymmetric models in a significant way, and future experiments should reach sensitivities which this kind of model must show effects, or become far less appealing

  17. Pion absorption in flight on 3He

    International Nuclear Information System (INIS)

    Ljungfelt, S.H.

    1985-02-01

    Pion absorption in flight on 3 He has been measured in a kinematically complete manner. The experiment was done in the πE1-channel at the Swiss Institute for Nuclear Research, SIN, using π + - and π - -beams of 120 and 165 MeV kinetic energy. Two of the emitted particles were measured in coincidence and identified by their time-of-flight/pulseheight relation. The obtained two-dimensional energy representation enabled a separation of the different kinematical regions and exhibited a clear enhancement in the region of quasifree absorption, QFA. (orig./WL)

  18. Study of the radiative pion decay

    International Nuclear Information System (INIS)

    Chen, Chuan-Hung; Geng, Chao-Qiang; Lih, Chong-Chung

    2011-01-01

    We study the radiative pion decay of π + →e + ν e γ in the light-front quark model. We also summarize the result in the chiral perturbation theory. The vector and axial-vector hadronic form factors (F V,A ) for the π→γ transition are evaluated in the whole allowed momentum transfer. In terms of these momentum dependent form factors, we calculate the decay branching ratio and compare our results with the experimental data and other theoretical predictions in the literature. We also constrain the possible size of the tensor interaction in the light-front quark model.

  19. Pion parton distribution functions from lattice QCD

    International Nuclear Information System (INIS)

    Wetzorke, I.; Jansen, K.; Shindler, A.; Palombi, F.

    2003-09-01

    We report on recent results for the pion matrix element of the twist-2 operator corresponding to the average momentum of non-singlet quark densities. For the first time finite volume effects of this matrix element are investigated and come out to be surprisingly large. We use standard Wilson and non-perturbatively improved clover actions in order to control better the extrapolation to the continuum limit. Moreover, we compute, fully non-perturbatively, the renormalization group invariant matrix element, which allows a comparison with experimental results in a broad range of energy scales. Finally, we discuss the remaining uncertainties, the extrapolation to the chiral limit and the quenched approximation. (orig.)

  20. Evidence for pion absorption on four nucleons

    International Nuclear Information System (INIS)

    Rzehorz, B.; Backenstoss, G.; Dzemidzic, M.; Zagreb Univ.; Furic, M.; Zagreb Univ.; Hoffart, A.; Petkovic, T.; Zagreb Univ.; Ullrich, H.; Weyer, H.J.; Weiser, D.; Wildi, M.

    1996-01-01

    Experimental spectra from the coincident detection of three nucleons after the pion absorption in 4 He are displayed. The presence of a mechanism with four nucleons participating in the absorption process is made obvious. The total cross-sections for this absorption mode are: σ 4NA abs =(1.0±0.2)mb at T π =120 MeV and σ 4NA abs =(2.18± 0.65) mb at T π =210 MeV. (orig.)

  1. Nuclear transparencies from photoinduced pion production

    Energy Technology Data Exchange (ETDEWEB)

    W. Cosyn; M.C. Martinez; J. Ryckebusch; B. Van Overmeire

    2006-12-01

    We present a relativistic and cross-section factorized framework for computing nuclear transparencies extracted from A({gamma}, {pi} N) reactions at intermediate energies. The proposed quantum mechanical model adopts a relativistic extension to the multiple-scattering Glauber approximation to account for the final state interactions of the ejected nucleon and pion. The theoretical predictions are compared against the experimental {sup 4}He({gamma},p {pi}{sup -}) data from Jefferson Lab. For those data, our results show no conclusive evidence for the onset of mechanisms related to color transparency.

  2. Isovector resonances in pion charge exchange

    International Nuclear Information System (INIS)

    Bowman, J.D.

    1985-01-01

    The (π ± , π 0 ) reactions as probes of isovector resonances are discussed. Experimental observation of the isovector monopole resonance is reported. Experimental results are presented for L=0, 1, and 2 isovector resonances and are compared to random-phase approximation calculations. In the experiments 40 Ca, 60 Ni, 90 Zr, 120 Sn, 140 Ce, and 208 Pb, targets were bombarded with 165 MeV π ± beams. Neutral pions were detected and double differential cross sections were determined for angles between 0 and 33deg and for π 0 energies between 90, 180, and 230 MeV. (Auth.)

  3. Pion and muon physics, ch. 2

    International Nuclear Information System (INIS)

    Dantzig, R. van; Goudsmit, P.F.A.; Konijn, J.

    1976-01-01

    A series of experiments in pion and muon physics has been planned for execution on the new IKO 500 MeV linac among which mesic X-rays PIμ capture gamma, PI-scattering and knock-out reactions are included. Progress in the construction of the PIμ facility and the development of instrumentation containing among other things drift chambers and an anti-Compton spectrometer has been reported. Also a few planned experiments in cooperation with CERN (along with others in the framework of the large magnetic analysis and detection system (OMICRON) developments) are described

  4. A chiral model for excited pions

    International Nuclear Information System (INIS)

    Volkov, M.K.; Weiss, C.

    1996-01-01

    We study radially excited mesons (π', σ') in a simple extension of the Nambu-Jona-Lasinio model with a polynomial meson-quark form factor. The form factor is introduced so that the usual form of the NJL gap equation remains unchanged. We derive the effective Lagrangian for π- and π'-mesons which describes the decoupling of the Goldstone pion in the chiral limit in agreement with current algebra. For π' masses in the range of 750 MeV and 1300 MeV f π' /f π is found to be of an order of one per cent. 12 refs

  5. Charge dependence of the pion-nucleon coupling constant

    Directory of Open Access Journals (Sweden)

    V. A. Babenko

    2015-07-01

    Full Text Available On the basis of the Yukawa potential we study the pion-nucleon coupling constants for the neutral and charged pions assuming that nuclear forces at low energies are mainly determined by the exchange of virtual pions. We obtain the charged pseudovector pion-nucleon coupling constant f2π± = 0.0804(7 by making the use of experimental low-energy scattering parameters for the singlet pp- and np-scattering, and also by use of the neutral pseudovector pion-nucleon coupling constant f2π0 = 0.0749(7. Corresponding value of the charged pseudoscalar pion-nucleon coupling constant g2π0 / 4π = 14.55(13 is also determined. This calculated value of the charged pseudoscalar pion-nucleon coupling constant is in fully agreement with the experimental constant g2π0 / 4π = 14.52(26 obtained by the Uppsala Neutron Research Group. Our results show considerable charge splitting of the pion-nucleon coupling constant.

  6. Experimental studies of pion-nucleus interactions at intermediate energies

    International Nuclear Information System (INIS)

    1991-01-01

    This report summarizes the work on experimental research in intermediate energy nuclear physics carried out at New Mexico State University in 1991 under a great from the US Department of Energy. Most of these studies have involved investigations of various pion-nucleus interactions. The work has been carried out both with the LAMPF accelerator at the Los Alamos National Laboratory and with the cyclotron at the Paul Scherrer Institute (PSI) near Zurich, Switzerland. Part of the experimental work involves measurements of new data on double-charge-exchange scattering, using facilities at LAMPF which we helped modify, and on pion absorption, using a new detector system at PSI that covers nearly the full solid-angle region which we helped construct. Other work involved preparation for future experiments using polarized nuclear targets and a new high-resolution spectrometer system for detecting π 0 mesons. We also presented several proposals for works to be done in future years, involving studies related to pi-mesonic atoms, fundamental pion-nucleon interactions, studies of the difference between charged and neutral pion interactions with the nucleon, studies of the isospin structure of pion-nucleus interactions, and pion scattering from polarized 3 He targets. This work is aimed at improving our understanding of the pion-nucleon interaction, of the pion-nucleus interaction mechanism, and of nuclear structure

  7. Time dependence of the masses of the pions

    Energy Technology Data Exchange (ETDEWEB)

    Boscoverde, Lello [IdFP, Garching (Germany)

    2013-07-01

    Recent work in Eddingtonian cosmology has demonstrated the relation of the visible mass of the universe to the spacial extent of the pions. Building on this finding, we conclude the masses of the pions themselves are dependent on the age of the universe. We present the previous work in this field as well as our new calculations.

  8. Pion form factor within QCD instanton vacuum model

    International Nuclear Information System (INIS)

    Dorokhov, A.E.

    1997-01-01

    Instanton induced pion wave function is constructed. It provides an intrinsic k 1 dependence which suppress soft virtual one-gluon exchanges and thus legitimate the perturbative QCD (pQCD) calculations of the pion electromagnetic form factor in the region of momentum transfers above the scale. (author)

  9. Two-pion production in photon-induced reactions

    Indian Academy of Sciences (India)

    A deeper understanding of the situation is anticipated from a detailed experimental study of meson photoproduction from nuclei in exclusive reactions. In the energy regime above the (1232) resonance, the dominant double pion production channels are of particular interest. Double pion photoproduction from nuclei is ...

  10. Where to look for pion condensation in heavy ion collisions

    International Nuclear Information System (INIS)

    Pirner, H.J.

    1994-08-01

    The possibility to observe a pion condensate in peripheral nucleus-nucleus collisions at GSI energies is discussed. A condensate may be observed via pronounced peaks in pion production in a narrow region of momenta k perpendicular to ≅(2-3)m π corresponding to rather large rapidity values. (orig.)

  11. Parity and isospin in pion condensation and tensor binding

    International Nuclear Information System (INIS)

    Pace, E.; Palumbo, F.

    1978-01-01

    In infinite nuclear matter with pion condensates or tensor binding both parity and isospin symmetries are broken. Finite nuclei with pion condensates or tensor binding, however, can have definite parity. They cannot have a definite value of isospin, whose average value is of the order of the number of nucleons. (Auth.)

  12. Pion interferometry theory for the hydrodynamic stage of multiple processes

    International Nuclear Information System (INIS)

    Makhlin, A.N.; Sinyukov, Yu.M.

    1986-01-01

    The double pion inclusive cross section for identical particles is described in hydrodynamical theory of multiparticle production. The pion interferometry theory is developed for the case when secondary particles are generated against the background of internal relativistic motion of radiative hadron matter. The connection between correlation functions in various schemes of experiment is found within the framework of relativistic Wigner functions formalism

  13. Pion production in high energy heavy ion collisions

    International Nuclear Information System (INIS)

    Wolf, K.L.; Bock, R.; Brockmann, R.

    1984-01-01

    Experimental data for heavy ion pion production reactions are compared with the predictions of a number of versions of cascade models. Pion suppression effects observed in the experimental data are fit by introducing refinements into cascade theory. Impact parameter adjustment, off-shell effects on the potential and perturbations due to nuclear matter are considered

  14. Pion correlation from Skyrmion--anti-Skyrmion annihilation

    International Nuclear Information System (INIS)

    Lu, Y.; Amado, R.D.

    1995-01-01

    We study two pion correlations from Skyrmion and anti-Skyrmion collision, using the product ansatz and an approximate random grooming method for nucleon projection. The spatial-isospin coupling inherent in the Skyrme model, along with empirical averages, leads to correlations not only among pions of like charges but also among unlike charge types

  15. Near-threshold charged pion photoproduction from 13C

    International Nuclear Information System (INIS)

    LeRose, J.J.

    1981-01-01

    Differential cross sections to discrete final states have been measured for both positive and negative pion photo-production on 13 C at 90 0 in the lab at pion energies of 18, 29, and 41 MeV. Measurements were made using a fixed angle magnetic spectrometer located in the 14 0 area of the MIT Bates linear accelerator. Pions were detected using a 90 channel multi-wire proportional counter in the focal plane along with a backup array consisting of three 1/16'' thick plastic scintillator detectors and a 1/2'' thick Cerenkov detector. Positive pion photo-production cross sections were obtained for the excitation of the 3/2 - ground state and for the 3.45 MeV first excited state of 13 B. Negative pion photo-production cross sections were obtained for the excitation of the 1/2 - ground state, and the 3/2 to 3.51 MeV and 5/2 to 7.39 MeV excited states of 13 N. The measured positive pion photo-production ground state cross sections are in reasonable agreement wth theoretical calculations. However, there is a large discrepancy between the measured negative pion photoproduction ground state cross sections and the theoretical values. There are no theoretical calculations available for comparison with the excited state measurements in either positive or negative pion photoproduction on 13 C

  16. Processes involved in pion capture in hydrogen-containing molecules

    International Nuclear Information System (INIS)

    Horvath, D.

    1983-03-01

    A systematic analysis is presented of the possible elementary processes determining the fate of negative pions stopped in hydrogen-containing samples. Using a phenomenological description in comparison with the available experimental information on pion capture in hydrogen, it is shown that the formation and decay of pπ - atoms in compounds Zsub(m)Hsub(n) are determined mainly by the processes of Auger capture in a molecular orbit ZHπ - , transition from molecular to atomic orbit, transfer of pions to atoms Z in collisions pπ - +Z, and nuclear capture in collisions pπ - +H. The recent assumption of a considerable role of the processes of radiative atomic capture in bound hydrogen atoms, nuclear capture of pions by protons from the molecular state ZHπ - , or 'inner' transfer of the pion via tunnelling through the bond Z-H is not supported by the theory and contradicts the experimental data

  17. Quantum signature in heavy-ion pion production

    International Nuclear Information System (INIS)

    Buvel, R.L.

    1985-01-01

    A revised model for pion production in heavy-ion peripheral collisions is presented. The pion-production mechanism investigated here is a two step process involving the formation and subsequent decay of an isobar resonance in the projectile nucleus. The independent-particle shell model with harmonic oscillator states is used to approximate the internal structure of the nucleus. The inclusion of the internal structure of the projectile nucleus led to the discovery of a quantum signature in the pion-production differential cross section. The quantum signature involves a matching condition where the pion-production differential cross section goes to zero for a particular value of the pion kinetic energy. The theory is compared to a recent experiment, but the results of this comparison are inconclusive

  18. Invariant potential for elastic pion--nucleus scattering

    International Nuclear Information System (INIS)

    Cammarata, J.B.; Banerjee, M.K.

    1976-01-01

    From the Wick-Dyson expansion of the exact propagator of a pion in the presence of a nucleus, an invariant potential for crossing symmetric elastic pion-nucleus scattering is obtained in terms of a series of pion-nucleon diagrams. The Chew-Low theory is used to develop a model in which the most important class of diagrams is effectively summed. Included in this model is the exclusion principle restriction on the pion-bound nucleon interaction, the effects of the binding of nucleons, a kinematic transformation of energy from the lab to the πN center of mass frame, and the Fermi motion and recoil of the target nucleons. From a numerical study of the effects of these processes on the π- 12 C total cross section, the relative importance of each is determined. Other processes contributing to the elastic scattering of pions not included in the present model are also discussed

  19. Collective flow of pions in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Russkikh, V.N.; Ivanov, Yu.B.

    1995-02-01

    The transverse-momentum distributions of pions in the Au(1 GeV/nucleon)+Au collisions are analyzed. The calculations are carried out within relativistic meanfield one- and two-fluid models. The rapidity distributions of the mean transverse momentum of pions are found to be fairly sensitive to the nuclear equation of state and, especially, to the stopping power. It is shown that the collective flow of pions in the reaction plane always correlates with the 'hot' flow of nucleons (i.e. those emitted from hot regions of nuclear system), while not always, with the total nucleon flow. This 'hot' nucleon flow can be experimentally singled out by selecting nucleons with sufficiently high transverse momenta. We predict that the 'hot' nucleon flow selected in this way will always correlate with the pion flow. Available experimental data on transverse-momentum spectra of pions are compared with calculations employing various equations of state and stopping power. (orig.)

  20. Effective pion--nucleon interaction in nuclear matter

    International Nuclear Information System (INIS)

    Celenza, L.S.; Liu, L.C.; Nutt, W.; Shakin, C.M.

    1976-01-01

    We discuss the modification of the interaction between a pion and a nucleon in the presence of an infinite medium of nucleons (nuclear matter). The theory presented here is covariant and is relevant to the calculation of the pion--nucleus optical potential. The specific effects considered are the modifications of the nucleon propagator due to the Pauli principle and the modification of the pion and nucleon propagators due to collisions with nucleons of the medium. We also discuss in detail the pion self-energy in the medium, paying close attention to off-shell effects. These latter effects are particularly important because of the rapid variation with energy of the fundamental pion--nucleon interaction. Numerical results are presented, the main feature being the appearance of a significant damping width for the (3, 3) resonance

  1. Puzzles in quarkonium hadronic transitions with two pion emission

    CERN Document Server

    Fernández, F.; Ortega, P.G.; Entem, D.R.

    2016-01-01

    The anomalously large rates of some hadronic transitions from quarkonium are studied using QCD multipole expansion (QCDME) in the framework of a constituent quark model which has been successful in describing hadronic phenomenology. The hybrid intermediate states needed in the QCDME method are calculated in a natural extension of our constituent quark model based on the Quark Confining String (QCS) scheme. Some of the anomalies are explained due to the presence of an hybrid state with a mass near the mass of the decaying resonance whereas other are justified by the presence of molecular components in the wave function. Some unexpected results are pointed out.

  2. Goldberger-Treiman discrepancy and the momentum variation of the pion-nucleon form factor and pion decay constant

    International Nuclear Information System (INIS)

    Coon, S.A.; Scadron, M.D.

    1981-01-01

    We suggest that the observed 6% Goldberger-Treiman discrepancy is due in part to a 3% variation in the pion-nucleon form factor and in part due to a 3% variation in the pion decay form factor from q 2 =m/sub π/ 2 to q 2 =0

  3. Double charge exchange of pions on nuclei

    International Nuclear Information System (INIS)

    Dzhibuti, R.I.; Kezerashvili, R.Y.

    1985-01-01

    An analysis is made of the results of experimental and theoretical studies during the last ten years of a unique process: double charge exchange of pions on nuclei. On the one hand, the commissioning of meson factories and the use of new and more accurate experimental methods have led to the accumulation of rich and reliable material for not only light but also medium and heavy nuclei. On the other hand, the development and application of new microscopic theoretical approaches have led to a deepening of our ideas about the mechanism of these exotic reactions at low, intermediate, and high energies. The currently existing methods of theoretical investigation and all possible reaction mechanisms are considered. Particular attention is devoted to double charge exchange of pions on the lightest nuclei, for the theoretical description of which it is possible to use the well-developed methods for investigating few-particle systems. The experimental investigations of double-isobar analog and nonanalog transitions in the reaction of double charge exchange are systematized

  4. Low energy pion-16O scattering

    International Nuclear Information System (INIS)

    Wafelbakker, C.K.

    1981-01-01

    In spite of some outward appearances, the modern microscopic theories of the pion-nucleus (πA) interaction are not fundamentally very different from each other. They can all be derived from the same source, multiple-scattering theory. They all treat the first-order optical potential in a comparatively detailed way and in all of them it is necessary to incorporate higher-order effects in general and pion-annihilation in particular phenomenologically. Basically the same physical features can be embodied in all of them. The presentation of the theoretical scheme underlying the present thesis is designed to stress this conceptual unity of current πA theory. In this thesis the methods developed by De Kam to incorporate Pauli- and binding-corrections to the impulse-approximation first-order optical potential for 4 He are extended to a more complicated nucleus, 16 O, for the first time. In concreto two situations are considered: π- 16 O scattering at energies below nucleon-knockout threshold (13.5 MeV) - 7 and 12 MeV - and at energies 40 and 49.7 MeV, above nucleon-knockout threshold but still well within the low-energy region. (Auth.)

  5. Neutrino production of single pions: Dipole description

    International Nuclear Information System (INIS)

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2011-01-01

    The light-cone distribution amplitudes for the axial current are derived within the instanton vacuum model, which incorporates nonperturbative effects including spontaneous chiral symmetry breaking. This allows one to extend applicability of the dipole approach, usually used in the perturbative domain, down to Q 2 →0, where the partially conserved axial current imposes a relation between the neutrino-production cross section and the one induced by pions. A dramatic breakdown of the Adler relation for diffractive neutrino production of pions, caused by absorptive corrections, was revealed recently by Kopeliovich et al.. Indeed, comparing with the cross section predicted by the dipole phenomenology at Q 2 →0 on a proton target we confirmed the sizable deviation from the value given by the Adler relation, as was estimated by Kopeliovich et al. within a simplified two-channel model. The dipole approach also confirms that in the black-disk limit, where the absorptive corrections maximize, the diffractive cross section ceases, on the contrary to the expectation based on the partially conserved axial current.

  6. Beam Spin Asymmetry Measurements for Two Pion Photoproduction at CLAS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark D. [Univ. of Glasgow, Scotland (United Kingdom)

    2015-09-01

    The overarching goal of this analysis, and many like it, is to develop our understanding of the strong force interactions within the nucleon by examining the nature of their excitation spectra. As the resonances of these spectra have very short lifetimes (tau = 1x10-23 s) and often have very similar masses, it is often impossible to directly observe resonances in the excitation spectra of nucleons. Polarization observables allow us to study the resonances by looking at how they affect the spin state of final state particles. The beam asymmetry is a polarization observable that allows us to detect the sensitivity of these resonances, and other transition mechanisms, to the electric vector orientation of incident photons. Presented in this thesis are first measurements of the beam asymmetries in the resonant region for the reaction channel pgamma p --> p π+ π-focusing on the intermediate mesonic states rho^0 and f^0, and the final state pions. The analysis used data from the g8b experiment undertaken at the Thomas Jefferson National Accelerator Facility (JLab), the first experiment at JLab to use a linearly polarized photon beam. Using the coherent Bremsstrahlung facility and the CLAS detector of Hall B at JLab allowed for many multi-channel reactions to be detected and the first measurements of many polarization observables including those presented here. A brief overview of the theoretical framework used to undertake this analysis is given, followed by a description of the experimental details of the facilities used, then a description of the calibration of the Bremsstrahlung tagging facility which the author undertook, and finally the analysis is presented and the resulting measurements.

  7. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    Constraints in the implementation of models of blended learning can be explained by several causes, but in this paper, it is illustrated that lack of sense of coherence is a major factor of these constraints along with the referential whole of the perceived learning environments. The question exa...

  8. Proton multiplicity distributions in pion-xenon nucleus collisions at 3.5 GeV/c

    International Nuclear Information System (INIS)

    Strugalski, Z.; Pawlak, T.; Peryt, W.; Pluta, J.

    1980-01-01

    Experimental results from the proton emission investigation in 3.5 GeV/c pion minus-xenon nucleus collisions detected in the 180 xenon bubble chamber are presented and analyzed. The emitted protons are of kinetic energies from 20 to 400 MeV. Multiplicity distributions of protons both accompanied and not accompanied by secondary charged and neutral pions are given. Large proton multiplicities are observed in the events without multiparticle production, the proton multiplicity distribution in this class of events being of an irregular character. The experimental results are well described in the model based on the following hypothesis: a high energy hadron traversing the target causes the monotonous emission of the fast protons in numbers nsub(p) being equal to the number of protons encountered in the neighbourhood of its path inside the nucleus target. In this case the multiple production goes through some intermediate states which decay after having left the target nucleus

  9. Effects of the pion string at heavy ion collisions

    International Nuclear Information System (INIS)

    Mao Hong; Li Yunde; East China Normal Univ., Shanghai

    2005-01-01

    The authors study the possible signals of the pion string associated with the QCD chiral phase transition in LHC Pb-Pb collision at energy √s=5.5 TeV. The authors follow the Kibble-Zurek mechanism to discuss the production and evolution of the pion string. The authors will show that if the QCD chiral phase transition really takes place in the LHC Pb-Pb collision process and the phase transition is in the second order, the pion string will be inevitably produced and subsequently decay. The main effect of this phenomenon is that there is a generation of a large number of pions in the final state produced by the decay of the pion string, and these pions are mostly distributed in a low momentum region with p-143 MeV; also there are lots of neutral pions distributed in a low momentum region with the mean momentum at p-21 MeV. (authors)

  10. Joint resummation for pion wave function and pion transition form factor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hsiang-nan [Institute of Physics, Academia Sinica,Academia Rd., Taipei, Taiwan 115 (China); Department of Physics, National Cheng-Kung University,University Rd., Tainan, Taiwan 701 (China); Department of Physics, National Tsing-Hua University,Kuang-Fu Rd., Hsinchu, Taiwan 300 (China); Shen, Yue-Long [College of Information Science and Engineering, Ocean University of China,Songling Rd, Qingdao, Shandong 266100 (China); Wang, Yu-Ming [Institut für Theoretische Teilchenphysik und Kosmologie RWTH Aachen,Physikzentrum Otto-Blumenthal-Straße, D-52056 Aachen (Germany); Physik Department T31, Technische Universität München,James-Franck-Straße, D-85748 Garching (Germany)

    2014-01-03

    We construct an evolution equation for the pion wave function in the k{sub T} factorization formalism, whose solution sums the mixed logarithm ln xln k{sub T} to all orders, with x (k{sub T}) being a parton momentum fraction (transverse momentum). This joint resummation induces strong suppression of the pion wave function in the small x and large b regions, b being the impact parameter conjugate to k{sub T}, and improves the applicability of perturbative QCD to hard exclusive processes. The above effect is similar to those from the conventional threshold resummation for the double logarithm ln{sup 2} x and the conventional k{sub T} resummation for ln{sup 2} k{sub T}. Combining the evolution equation for the hard kernel, we are able to organize all large logarithms in the γ{sup ∗}π{sup 0}→γ scattering, and to establish a scheme-independent k{sub T} factorization formula. It will be shown that the significance of next-to-leading-order contributions and saturation behaviors of this process at high energy differ from those under the conventional resummations. It implies that QCD logarithmic corrections to a process must be handled appropriately, before its data are used to extract a hadron wave function. Our predictions for the involved pion transition form factor, derived under the joint resummation and the input of a non-asymptotic pion wave function with the second Gegenbauer moment a{sub 2}=0.05, match reasonably well the CLEO, BaBar, and Belle data.

  11. Photoproduction of positive pions from polarized protons in the region of the first resonance

    Energy Technology Data Exchange (ETDEWEB)

    Get' man, V.A.; Gorbenko, V.G.; Derkach, A.Y.; Zhebrovskii, Y.V.; Karnaukhov, I.M.; Kolesnikov, L.Y.; Kuz' menko, V.S.; Lukhanin, A.A.; Ranyuk, Y.N.; Rubashkin, A.L.; Sanin, V.M.; Sorokin, P.V.; Sporov, E.A.; Telegin, Y.N.; Shalatskii, S.V.; Grushin, V.F.

    1980-04-01

    A technique for measuring the T asymmetry for the process ..gamma..p ..-->.. n..pi../sup +/ using a polarized proton target and a quasimonochromatic beam of photons is described. The results of measuring T in the range of pion-emission angles theta(/sub ..pi../ = 3 to 150/sup 0/ at a photon energy of 340 MeV are presented and discussed. It is shown that the results obtained allow a more reliable selection of the solutions of the energy-independent multipole analysis.

  12. Single pion production in neutrino-nucleon interactions

    Science.gov (United States)

    Kabirnezhad, M.

    2018-01-01

    This work represents an extension of the single pion production model proposed by Rein [Z. Phys. C 35, 43 (1987)., 10.1007/BF01561054]. The model consists of resonant pion production and nonresonant background contributions coming from three Born diagrams in the helicity basis. The new work includes lepton mass effects, and nonresonance interaction is described by five diagrams based on a nonlinear σ model. This work provides a full kinematic description of single pion production in the neutrino-nucleon interactions, including resonant and nonresonant interactions in the helicity basis, in order to study the interference effect.

  13. Hard exclusive pion electroproduction at backward angles with CLAS

    Science.gov (United States)

    Park, K.; Guidal, M.; Gothe, R. W.; Pire, B.; Semenov-Tian-Shansky, K.; Laget, J.-M.; Adhikari, K. P.; Adhikari, S.; Akbar, Z.; Avakian, H.; Ball, J.; Balossino, I.; Baltzell, N. A.; Barion, L.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Cao, F. T.; Carman, D. S.; Celentano, A.; Charles, G.; Chetry, T.; Ciullo, G.; Clark, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Defurne, M.; Deur, A.; Djalali, C.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fersch, R.; Filippi, A.; Garçon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Girod, F. X.; Golovatch, E.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Heddle, D.; Hicks, K.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Johnston, S.; Joo, K.; Kabir, M. L.; Keller, D.; Khachatryan, G.; Khachatryan, M.; Khandaker, M.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuhn, S. E.; Lanza, L.; Livingston, K.; MacGregor, I. J. D.; Markov, N.; McKinnon, B.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Paolone, M.; Paremuzyan, R.; Pasyuk, E.; Phelps, W.; Pogorelko, O.; Poudel, J.; Price, J. W.; Prok, Y.; Protopopescu, D.; Ripani, M.; Rizzo, A.; Rossi, P.; Sabatié, F.; Salgado, C.; Schumacher, R. A.; Sharabian, Y.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tan, J. A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Wei, X.; Zachariou, N.; Zhang, J.

    2018-05-01

    We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, ep →e‧ nπ+, above the resonance region at backward pion center-of-mass angles. The φπ* -dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs). These non-perturbative objects are defined as matrix elements of three-quark-light-cone-operators and characterize partonic correlations with a particular emphasis on baryon charge distribution inside a nucleon.

  14. High-energy pion beams: Problems and prospects

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1992-01-01

    The investigation of relatively unexplored research areas with high energy pion beams requires new facilities. Presently existing meson factories such as LAMPF, TRIUMF and PSI provide insufficient pion fluxes above the 3,3 resonance region for access to topics such as strangeness production with the (π, K) reaction, baryon resonances, rare meson decays, and nuclear studies with penetrating pion beams. The problems and prospects of useful beams for these studies will be reviewed, both for existing facilities such as the AGS and KEK, and for possible future facilities like KAON and PILAC

  15. Tensor polarization in pion-deuteron elastic scattering

    International Nuclear Information System (INIS)

    Holt, R.J.; Freeman, W.S.; Geesaman, D.F.

    1985-01-01

    During this year the analysis of measurements of t 20 in π-d elastic scattering was completed and a final summary manuscript was prepared for publication. The results consists of angular distributions of the deuteron tensor polarization in π-d elastic scattering at pion energies of 140, 180, 220 and 256 MeV. Theoretical calculations in which the effects of pion absorption on the elastic channel are small reproduce the data. No rapid angular or energy dependence was found near a pion energy of 134 MeV, where another experiment at SIN has suggested the existence of dibaryon resonances

  16. Pion condensation and density isomerism in nuclear matter

    International Nuclear Information System (INIS)

    Hecking, P.; Weise, W.

    1979-01-01

    The possible existence of density isomers in nuclear matter, induced by pion condensation, is discussed; the nuclear equation of state is treated within the framework of the sigma model. Repulsive short-range baryon-baryon correlations, the admixture of Δ (1232) isobars and finite-range pion-baryon vertex form factors are taken into account. The strong dependence of density isomerism on the high density extrapolation of the equation of state for normal nuclear matter is also investigated. We find that, once finite range pion-baryon vertices are introduced, the appearance of density isomers becomes unlikely

  17. Forward pion-nucleon charge exchange reaction and Regge constraints

    International Nuclear Information System (INIS)

    Huang Fei; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meibner, U.-G.

    2009-01-01

    We present our recent study of pion-nucleon charge exchange amplitudes above 2 GeV. We analyze the forward pion-nucleon charge exchange reaction data in a Regge model and compare the resulting amplitudes with those from the Karlsruhe-Helsinki and George-Washington-University partial-wave analyses. We explore possible high-energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV. Our results show that for the pion-nucleon charge exchange reaction, the appropriate energy region for matching meson-nucleon dynamics to diffractive scattering should be around 3 GeV for the helicity flip amplitude. (authors)

  18. Recent developments in the understanding of pion-nucleus scattering

    International Nuclear Information System (INIS)

    Johnson, M.B.

    1983-01-01

    A development of the theory of pion-nucleus scattering is given in a field theoretical framework. The theory is designed to describe pion elastic scattering and single- and double-charge exchange to isobaric analog states. An analysis of recent data at low and resonance energies is made. Strong modifications to the simple picture of the scattering as a succession of free pion-nucleon interactions are required in order to understand the data. The extent to which the experiment is understood in terms of microscopic theory is indicated. 71 references

  19. Remarks on the pion-nucleon σ-term

    Science.gov (United States)

    Hoferichter, Martin; Ruiz de Elvira, Jacobo; Kubis, Bastian; Meißner, Ulf-G.

    2016-09-01

    The pion-nucleon σ-term can be stringently constrained by the combination of analyticity, unitarity, and crossing symmetry with phenomenological information on the pion-nucleon scattering lengths. Recently, lattice calculations at the physical point have been reported that find lower values by about 3σ with respect to the phenomenological determination. We point out that a lattice measurement of the pion-nucleon scattering lengths could help resolve the situation by testing the values extracted from spectroscopy measurements in pionic atoms.

  20. Pion condensation in cold dense matter and neutron stars

    International Nuclear Information System (INIS)

    Haensel, P.; Proszynski, M.

    1982-01-01

    We study possible influence, on the neutron star structure, of a pion condensation occurring in cold dense matter. Several equations of state with pion-condensed phase are considered. The models of neutron stars are calculated and confronted with existing observational data on pulsars. Such a confrontation appears to rule out the models of dense matter with an abnormal self-bound state, and therefore it seems to exclude the possibility of the existence of abnormal superheavy neutron nuclei and abnormal neutron stars with a liquid pion-condensed surface

  1. Correlations of neutral pions in ultrarelativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Peitzmann, T.; Beckmann, P.; Berger, F.; Glewing, G.; Dragon, L.; Glasow, R.; Kampert, K.H.; Loehner, H.; Purschke, M.; Santo, R.; Albrecht, R.; Bock, R.; Claesson, G.; Gutbrod, H.H.; Kolb, B.W.; Lund, I.; Schmidt, H.R.; Siemiarczuk, T.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Lee, I.Y.; Obenshain, F.E.; Plasil, F.; Soerensen, S.P.; Young, G.R.; Eklund, A.; Garpman, S.; Gustafsson, H.A.; Idh, J.; Kristiansson, P.; Oskarsson, A.; Otterlund, I.; Persson, S.; Stenlund, E.; Franz, A.; Poskanzer, A.M.; Ritter, H.G.

    1989-01-01

    Correlations of 4 photons representing neutral pions have been studied in ultrarelativistic heavy ion collisions. Data were taken in the WA80 experiment at the CERN-SPS with a 200 A GeV oxygen beam. The π 0 are detected via their decay photons with a high-granularity lead glass array. Special features of interferometry using neutral pions will be discussed. The extracted preliminary parameters for high p T pions emitted near midrapidity in O+Au collisions lead to rather small effective source sizes. (orig.)

  2. Universal pion freeze-out in heavy-ion collisions.

    Science.gov (United States)

    Adamová, D; Agakichiev, G; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanović, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Z; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B; Ludolphs, W; Maas, A; Marín, A; Milosević, J; Milov, A; Miśkowiec, D; Panebrattsev, Yu; Petchenova, O; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schukraft, J; Sedykh, S; Shimansky, S; Slívová, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, I; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

    2003-01-17

    Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.

  3. Universal pion freeze-out in heavy-ion collisions

    CERN Document Server

    Adamova, D; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B C; Ludolphs, W; Maas, A; Marin, A; Milosevic, J; Milov, A; Miskowiec, D; Panebratsev, Yu A; Petchenova, O Yu; Petracek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schükraft, Jürgen; Sedykh, S; Shimansky, S S; Slivova, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V; Schmitz, W

    2003-01-01

    Based on an evaluation of recent systematic data on two-pion interferometry and on measured particle yields at mid-rapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda_f reaches a value of approximately 2.5 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and its value is constant at all currently available beam energies from AGS to RHIC.

  4. Double recharge of pions on a deuterium

    International Nuclear Information System (INIS)

    Nichitiu, F.; Falomkin, I.V.; Shcherbakov, Yu.A.

    1987-01-01

    Assumptions on the dibaryon nature of the existing narrow resonances below the threshold of the NΔ-state with masses 1935, 1965, 2015 MeV are considered. New proposals on construction of the particle systematics with a new particle (R-particle of mass 1025 MeV, J=1/2, T=3/2) are used to draw a conclusion that double charge exchange is possible on deuterium and helium-3 if dibaryons or new R-particles are born in the final state. Attention is paid to a possible decay of these particles through a weak channel. A search for double charge exchange of pions on hydrogen and deuterium using a laser-illuminated streamer chamber of high pressure is proposed

  5. Deuteron Compton scattering below pion photoproduction threshold

    Science.gov (United States)

    Levchuk, M. I.; L'vov, A. I.

    2000-07-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  6. Deuteron Compton scattering below pion photoproduction threshold

    International Nuclear Information System (INIS)

    Levchuk, M.I.; L'vov, A.I.

    2000-01-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data

  7. Deuteron Compton scattering below pion photoproduction threshold

    Energy Technology Data Exchange (ETDEWEB)

    Levchuk, M.I. E-mail: levchuk@dragon.bas-net.by; L' vov, A.I. E-mail: lvov@x4u.lebedev.ru

    2000-07-17

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  8. Pions, delta's and quarks in nuclei

    International Nuclear Information System (INIS)

    Laget, J.M.

    1983-10-01

    Nuclear Physics has now evolved from the study of the many nucleon problem, to the study of the interplay of the degrees of freedom of such a complex system and the internal degrees of freedom of each of its hadronic constituents. Extensive studies of electronuclear reactions have all allowed us to disentangle the basic mechanisms of the interaction between two baryons in a nucleus. The pion exchange mechanisms, which dominates at large distance has been singled out. The NΔ interaction, which enter the description of the intermediate range part, has been studied. Evidences for effects due to the quark structure of the nucleon have been found. But more systematic studies are needed to study them in detail

  9. The pion's pioneers

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    In 1946, a band of intrepid physicists took a batch of a new kind of photographic emulsion up the Pic du Midi in the French Pyrenees to expose them to cosmic rays. After analysing the results at Bristol, C. M. G. Lattes, H. Muirhead, G. P. S. Occhialini and C. F. Powell were able to announce early the following year that they had seen the long-awaited pi meson, or pion, postulated by Yukawa in 1935 as the carrier of the strong nuclear force. This landmark discovery quickly revitalized particle physics after all its wartime upheavals. At the end of July, the H. H. Wills Physics Laboratory at Bristol was the scene of an unusual and memorable international conference to mark the 40th anniversary of this discovery

  10. Quasi-free pion single charge exchange

    International Nuclear Information System (INIS)

    Ouyang, J.

    1992-12-01

    Cross sections for the quasi-free (QF) region for pion single charge exchange (SCX) were measured with beams of 475 MeV π - , 500 MeV π ± , and 400 MeV π - , with most data at 500 MeV π ± . The LAMPF π 0 spectrometer and a proton detector arm were placed on each side of the beam with different scattering angles. Up to twelve targets, from hydrogen to bismuth, were used. Both inclusive and coincidence measurements were performed. The extraction of peak shape and cross section for the QF peak, the effective number of nucleons involved in the reaction, mass dependence, and angular dependence were studied for the inclusive measurement. Calculations with the local random phase approximation (RPA) were used to understand the inclusive experimental results. A collection of experimental results is given for both inclusive and coincidence measurements

  11. Systematics of pion double charge exchange

    International Nuclear Information System (INIS)

    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 π/ = 0 + states were performed within a distorted-wave impulse-approximation framework. The sensitivities of these calculations to input parameters are discussed. 58 refs., 41 figs., 16 tabs

  12. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase...

  13. In-medium pion valence distributions in a light-front model

    Energy Technology Data Exchange (ETDEWEB)

    Melo, J.P.B.C. de, E-mail: joao.mello@cruzeirodosul.edu.br [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Tsushima, K. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Ahmed, I. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); National Center for Physics, Quaidi-i-Azam University Campus, Islamabad 45320 (Pakistan)

    2017-03-10

    Pion valence distributions in nuclear medium and vacuum are studied in a light-front constituent quark model. The in-medium input for studying the pion properties is calculated by the quark-meson coupling model. We find that the in-medium pion valence distribution, as well as the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

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

    International Nuclear Information System (INIS)

    Baer, H.W.; Leitch, M.J.

    1985-09-01

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

  15. Pion interactions with light nuclei and applications to radiotherapy

    International Nuclear Information System (INIS)

    Brenner, D.J.

    1979-02-01

    In the light of the current interest in negative pion radiotherapy particle spectra have been obtained after negative pion absorption in oxygen. Using a multiple foil activation technique, measurements were made of neutron spectra from the pion interactions and also from background sources from which it appears that the technique is a potentially useful tool for routine dosimetry. Theoretical predictions are made of the energy spectra of particles emitted after stopped pion absorption on oxygen based on an alpha cluster model and using a plane-wave impulse approximation. A method of considering residual interactions with the nucleus is described which has the potential to treat the low energy particles and also final channels not expected as a result of a single interaction. (UK)

  16. Toy model for pion production in nucleon-nucleon collisions

    International Nuclear Information System (INIS)

    Hanhart, C.; Miller, G. A.; Myhrer, F.; Sato, T.; Kolck, U. van

    2001-01-01

    We develop a toy model for pion production in nucleon-nucleon collisions that reproduces some of the features of the chiral Lagrangian calculations. We calculate the production amplitude and examine some common approximations

  17. On the role of secondary pions in spallation targets

    Energy Technology Data Exchange (ETDEWEB)

    Mancusi, Davide [Paris-Saclay Univ., Gif-sur-Yvette (France). Den-Service d' Etude des Reacteurs et de Mathematiques Appliquees (SERMA); Lo Meo, Sergio [ENEA, Research Centre ' ' Ezio Clementel' ' , Bologna (Italy); INFN, Bologna (Italy); Colonna, Nicola [INFN, Bari (Italy); Boudard, Alain; David, Jean-Christophe; Leray, Sylvie [Paris-Saclay Univ., Gif-sur-Yvette (France). IRFU, CEA; Cortes-Giraldo, Miguel Antonio; Lerendegui-Marco, Jorge [Sevilla Univ. (Spain). Facultad de Fisica; Cugnon, Joseph [Liege Univ. (Belgium). AGO Dept.; Massimi, Cristian [INFN, Bologna (Italy); Bologna Univ. (Italy). Physics and Astronomy Dept.; Vlachoudis, Vasilis [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2017-05-15

    We use particle-transport simulations to show that secondary pions play a crucial role for the development of the hadronic cascade and therefore for the production of neutrons and photons from thick spallation targets. In particular, for the nTOF lead spallation target, irradiated with 20 GeV/c protons, neutral pions are involved in the production of ∝ 90% of the high-energy photons; charged pions participate in ∝ 40% of the integral neutron yield. Nevertheless, photon and neutron yields are shown to be relatively insensitive to large changes of the average pion multiplicity in the individual spallation reactions. We characterize this robustness as a peculiar property of hadronic cascades in thick targets. (orig.)

  18. Strange Twists in Neutral Pion Photo/Electro-Production

    OpenAIRE

    Meißner, Ulf-G.

    1995-01-01

    I review the interesting tale of the electric dipole amplitude in neutral pion photoproduction and the resulting consequences. I also discuss why there is new life related to P--wave multipoles. Electroproduction is briefly touched upon.

  19. Isospin breaking in the pion-nucleon scattering lengths

    International Nuclear Information System (INIS)

    Hoferichter, Martin; Kubis, Bastian; Meissner, Ulf-G.

    2009-01-01

    We analyze isospin breaking through quark mass differences and virtual photons in the pion-nucleon scattering lengths in all physical channels in the framework of covariant baryon chiral perturbation theory.

  20. Isospin breaking in the pion-nucleon scattering lengths

    Energy Technology Data Exchange (ETDEWEB)

    Hoferichter, Martin [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Kubis, Bastian [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany)], E-mail: kubis@itkp.uni-bonn.de; Meissner, Ulf-G. [Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Institut fuer Kernphysik (Theorie), Institute for Advanced Simulation, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany)

    2009-07-06

    We analyze isospin breaking through quark mass differences and virtual photons in the pion-nucleon scattering lengths in all physical channels in the framework of covariant baryon chiral perturbation theory.

  1. Quantitative assessment of target dependence of pion fluctuation in ...

    Indian Academy of Sciences (India)

    journal of. December 2012 physics pp. 1395–1405. Quantitative assessment ... The analysis reveals the erratic behaviour of the produced pions signifying ..... authors (Sitaram Pal) gratefully acknowledges the financial help from the University.

  2. Experimental studies of pion-nucleus interactions at intermediate energies

    International Nuclear Information System (INIS)

    1992-01-01

    This report summarizes investigations of various pion-nucleus interactions and nucleon-nucleus charge-exchange reactions. The work was carried out with the LAMPF accelerator at the Los Alamos National Laboratory and the cyclotrons at the Paul Scherrer Institute (PSI) near Zurich, Switzerland, and at Indiana University (IUCF), as a collaborative effort among several laboratories and universities. The experimental activity at LAMPF involved measurements of new data on pion double-charge-exchange scattering, some initial work on a new Neutral Meson Spectrometer system, a search for deeply-bound pionic atoms, measurements of elastic scattering, and studies of the (n,p) reaction on various nuclei. At PSI measurements of pion quasielastic scattering were carried out, with detection of the recoil proton. Work on the analysis of data from a previous experiment at PSI on pion absorption in nuclei was continued. This experiment involved using a detector system that covered nearly the full solid angle

  3. Deeply virtual compton scattering on a virtual pion target

    International Nuclear Information System (INIS)

    Amrath, D.; Diehl, M.; Lansberg, J.P.; Heidelberg Univ.

    2008-07-01

    We study deeply virtual Compton scattering on a virtual pion that is emitted by a proton. Using a range of models for the generalized parton distributions of the pion, we evaluate the cross section, as well as the beam spin and beam charge asymmetries in the leading-twist approximation. Studying Compton scattering on the pion in suitable kinematics puts high demands on both beam energy and luminosity, and we find that the corresponding requirements will first be met after the energy upgrade at Jefferson Laboratory. As a by-product of our study, we construct a parameterization of pion generalized parton distributions that has a non-trivial interplay between the x and t dependence and is in good agreement with form factor data and lattice calculations. (orig.)

  4. The possibility for a pion polarizability measurement at COMPASS

    CERN Document Server

    Guskov, A

    2010-01-01

    The pion electromagnetic structure can be probed in $\\pi^{−}+(A,Z)\\rightarrow\\pi^{-}+(A,Z) + \\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric $(\\alpha_{\\pi})$ and the magnetic $(\\beta_{\\pi})$ polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of point-like pions with the measured cross section. The opportunity to measure pion polarizability via the Primakoff reaction at the COMPASS experiment was studied with a $\\pi^{−}$ beam of 190 GeV. The obtained results are used for preparation of the new measurement.

  5. Roy-Steiner-equation analysis of pion-nucleon scattering

    Science.gov (United States)

    Meißner, U.-G.; Ruiz de Elvira, J.; Hoferichter, M.; Kubis, B.

    2017-03-01

    Low-energy pion-nucleon scattering is relevant for many areas in nuclear and hadronic physics, ranging from the scalar couplings of the nucleon to the long-range part of two-pion-exchange potentials and three-nucleon forces in Chiral Effective Field Theory. In this talk, we show how the fruitful combination of dispersion-theoretical methods, in particular in the form of Roy-Steiner equations, with modern high-precision data on hadronic atoms allows one to determine the pion-nucleon scattering amplitudes at low energies with unprecedented accuracy. Special attention will be paid to the extraction of the pion-nucleon σ-term, and we discuss in detail the current tension with recent lattice results, as well as the determination of the low-energy constants of chiral perturbation theory.

  6. On the role of secondary pions in spallation targets

    CERN Document Server

    Mancusi, Davide; Colonna, Nicola; Boudard, Alain; Cortés-Giraldo, Miguel Antonio; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie; Lerendegui-Marco, Jorge; Massimi, Cristian; Vlachoudis, Vasilis

    2017-01-01

    We use particle-transport simulations to show that secondary pions play a crucial role for the development of the hadronic cascade and therefore for the production of neutrons and photons from thick spallation targets. In particular, for the n_TOF lead spallation target, irradiated with 20-GeV/c protons, neutral pions are involved in the production of ~90% of the high-energy photons; charged pions participate in ~40% of the integral neutron yield. Nevertheless, photon and neutron yields are shown to be relatively insensitive to large changes of the average pion multiplicity in the individual spallation reactions. We characterize this robustness as a peculiar property of hadronic cascades in thick targets.

  7. Coherent radiation from pulsars

    International Nuclear Information System (INIS)

    Cox, J.L. Jr.

    1979-01-01

    Interaction between a relativistic electrom stream and a plasma under conditions believed to exist in pulsar magnetospheres is shown to result in the simultaneous emission of coherent curvature radiation at radio wavelengths and incoherent curvature radiation at X-ray wavelengths from the same spatial volume. It is found that such a stream can propagate through a plasma parallel to a very strong magnetic field only if its length is less than a critical length L/sub asterisk/ic. Charge induced in the plasma by the stream co-moves with the stream and has the same limitation in longitudinal extent. The resultant charge bunching is sufficient to cause the relatively low energy plasma particles to radiate at radio wavelengths coherently while the relatively high energy stream particles radiate at X-ray wavelengths incoherently as the stream-plasma system moves along curved magnetic field lines. The effective number of coherently radiating particles per bunch is estimated to be approx.10 14 --10 15 for a tupical pulsar

  8. Doubly coherent production of π- by 3He ions of 910 MeV

    International Nuclear Information System (INIS)

    Aslanides, E.; Fassnacht, P.; Hibou, F.; Chiavassa, E.; Dellacasa, G.; Gallio, M.; Musso, A.; Bressani, T.; Puddu, G.

    1979-01-01

    The inclusive pion spectrum from the reaction 3 He+ 6 Li → π - +X at 910 MeV was measured at 0 0 with moderate resolution up to the kinematic limit of the two-body final-state reaction. A first analysis shows that the production of high-energy pions cannot be explained by the NN → NNπ process using conventional nucleon momentum distributions. At the end of the spectrum a clear deviation from the general falloff slope is observed and attributed to the doubly coherent reaction 3 He+ 6 Li → 9 C+π -

  9. Coherent Baryogenesis

    CERN Document Server

    Garbrecht, B; Schmidt, M G; Garbrecht, Bjorn; Prokopec, Tomislav; Schmidt, Michael G.

    2004-01-01

    We propose a new baryogenesis scenario based on coherent production and mixing of different fermionic species. The mechanism is operative during phase transitions, at which the fermions acquire masses via Yukawa couplings to scalar fields. Baryon production is efficient when the mass matrix is nonadiabatically varying, nonsymmetric and when it violates CP and B-L directly, or some other charges that are eventually converted to B-L. We first consider a toy model, which involves two mixing fermionic species, and then a hybrid inflationary scenario embedded in a supersymmetric Pati-Salam GUT. We show that, quite generically, a baryon excess in accordance with observation can result.

  10. Power corrections to the asymptotics of the pion electromagnetic formfactor

    International Nuclear Information System (INIS)

    Gorsky, A.S.

    1984-01-01

    The first power correction to the pion electromagnetic form factor is derived. A few asymptotic wave functions corresponding to the different series of operators and matrix elements of four-particle operators in pion have been found. The large scale of the first power correction approximately 10 2 (GeV 2 )/Q 2 where Q 2 is the momentum transfer indicates that at low energies the whole series of power corrections seems to be taken into account

  11. Pion interferometry of ultra-relativistic hadronic collisions

    International Nuclear Information System (INIS)

    Kolehmainen, K.

    1986-05-01

    Pion interferometry of ultra-relativistic hadronic collisions is described in the context of the inside-outside cascade model using a current ensemble method capable of describing an arbitrary distribution of pion sources with an arbitrary velocity distribution. The results are quite distinct from the usual Gaussian and Kopylov parameterizations. Extraction of the temperature parameter, effective source lifetime, and transverse size requires a full three-dimensional analysis of the correlation function in terms of the momentum difference. 7 refs., 4 figs

  12. The TRIUMF low energy pion spectrometer and channel

    International Nuclear Information System (INIS)

    Sobie, R.J.; Drake, T.E.; Barnett, B.M.; Erdman, K.L.; Gyles, W.; Johnson, R.R.; Roser, H.W.; Tacik, R.; Blackmore, E.W.; Gill, D.R.

    1983-08-01

    A low energy pion spectrometer has been developed for use with the TRIUMF M13 pion channel. The combined channel and spectrometer resolution is presently 1.1 MeV at T = 50 MeV. This is limited by the amount of gas and detector material in the spectrometer in addition to the inherent resolution of the channel. Improvements to both the spectrometer and channel are discussed

  13. Quantitative tests of pion physics in simple nuclear systems

    International Nuclear Information System (INIS)

    Ericson, T.E.O.

    1984-01-01

    The need for quantitative tests of pion physics in simple nuclear systems is discussed under eight topic headings. These include: one-pion exchange potential, p-wave NN scattering lengths, opep pole in forward NN dispersion relations, np → pn near the forward direction, pionic interactions, deuteron D/S ratio eta, deuteron quadrupole moment, and finally the joint case of eta and Q. (U.K.)

  14. A relativistic, meson exchange model of pion-nucleon scattering

    International Nuclear Information System (INIS)

    Pearces, B.C.; Jennings, B.K.

    1990-06-01

    A relativistic meson exchange approach to the pion-nucleon interaction is developed using a three-dimensional relativistic two-body propagator, and the results using different propagators are compared. The relativistic approach is able to describe low energy scattering up to 400 MeV above threshold, while preserving the soft pion theorems. The different propagators give similar results, as the form factors necessary to get a fit suppress much of the multiple scattering. (Author) (24 refs., 4 tabs., 6 figs.)

  15. Asymptotical behaviour of pion electromagnetic form factor in QCD

    International Nuclear Information System (INIS)

    Efremov, A.V.; Radyushkin, A.V.

    1978-01-01

    In the framework of the renormalizable quantum field theory a new approach is developed to the investigation of asymptotical behaviour of two-particle bound state electromagnetic form factor. It is shown that the behaviour of the pion EM form factor in quantum chromodynamics at sufficiently large momentum transfers is controlled by the short-distance dynamics only. The formula is obtained which expresses the asymptotical behaviour of the pion form factor in terms of the fundamental constants of the theory

  16. Dosimetry and radiobiology of negative pions and heavy ions

    International Nuclear Information System (INIS)

    Raju, M.R.

    1978-01-01

    The depth dose distribution of pion beams has not been found superior to protons. Pion radiation quality at the plateau region is comparable to conventional low-LET radiations, and radiobiology results also indicate RBE values close to unity. In the pion stopping region, the radiation quality increases considerably. Radiobiology data for negative pions at the Bragg peak position clearly indicate the increase in RBE and the reduction in OER. Even at the Bragg peak position, compared to fast neutrons, the average LET of negative pions is lower. Pion radiobiology data have indicated lower RBE values and higher OER values compared to fast neutrons. The radiation quality of fast neutrons is in between that of carbon and neon ions at the peak region and that of neon ions at the plateau is lower than for fast neutrons. The mean LET value for helium ions, even at the distal end of the peak, is lower than for fast neutrons. Dose localization of heavy ions has been found to decrease slowly with increasing charge of the heavy ion. The intercellular contact that protects cells after exposure to low-LET radiations is not detected after exposure to heavy ions. Single and fractionated doses of heavy ions produce dose-response curves for heavy ions having reduced shoulders but similar slopes when compared to gamma rays. Fractionated treatments of heavy ions produce an enhanced effect in the peak region compared to the plateau region and could lead to a substantial gain in therapeutic ratio. The OER for protons was similar to that for x rays. The OER values for negative pions, helium ions, and carbon ions were larger, for neon ions similar, and for argon ions smaller when compared to fast neutrons.Negative pions, helium ions, and carbon ions may be very effective clinically because the radiation quality of these beams is similar to that of the mixed scheme of neutrons and x rays

  17. On the origin of the pion in confinement schemes

    International Nuclear Information System (INIS)

    Brout, R.; Englert, F.; Frere, J.-M.

    1978-01-01

    It is argued that the 't Hooft one-dimensional gauge model is a good starting point on how to conceive the pion in confinement schemes. The results of Wu on the quark propagator in this model are analyzed in the light of spontaneously broken chiral symmetry and the existence of the pion is deduced. The corresponding Bethe-Salpeter wave function is exhibited. (Auth.)

  18. Di-photon resonance and Dark Matter as heavy pions

    CERN Document Server

    Redi, Michele; Tesi, Andrea; Vigiani, Elena

    2016-05-13

    We analyse confining gauge theories where the 750 GeV di-photon resonance is a composite techni-pion that undergoes anomalous decays into SM vectors. These scenarios naturally contain accidentally stable techni-pions Dark Matter candidates. The di-photon resonance can acquire a larger width by decaying into Dark Matter through the CP-violating $\\theta$-term of the new gauge theory reproducing the cosmological Dark Matter density as thermal relic.

  19. The transverse spin structure of the pion at short distances

    International Nuclear Information System (INIS)

    Diehl, Markus; Szymanowski, Lech; Ecole Polytechnique, CNRS, Palaiseau; Paris-Sud Univ., CNRS, Orsay

    2010-03-01

    We study the form factors of the quark tensor currents in the pion at large squared momentum transfer Q 2 . It turns out that certain form factors can be evaluated using collinear factorization, whereas others receive important contributions from the end-point regions of the longitudinal quark momenta in the pion. We derive simple analytic expressions for the dominant terms at high Q 2 and illustrate them numerically. (orig.)

  20. Finite size effects of a pion matrix element

    International Nuclear Information System (INIS)

    Guagnelli, M.; Jansen, K.; Palombi, F.; Petronzio, R.; Shindler, A.; Wetzorke, I.

    2004-01-01

    We investigate finite size effects of the pion matrix element of the non-singlet, twist-2 operator corresponding to the average momentum of non-singlet quark densities. Using the quenched approximation, they come out to be surprisingly large when compared to the finite size effects of the pion mass. As a consequence, simulations of corresponding nucleon matrix elements could be affected by finite size effects even stronger which could lead to serious systematic uncertainties in their evaluation

  1. The transverse spin structure of the pion at short distances

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus, E-mail: mdiehl@mail.desy.d [Deutsches Elektronen-Synchroton DESY, 22603 Hamburg (Germany); Szymanowski, Lech [Soltan Institute for Nuclear Studies, Warsaw (Poland); Centre de Physique Theorique, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Laboratoire de Physique Theorique, Universite Paris-Sud, CNRS, 91405 Orsay (France)

    2010-06-14

    We study the form factors of the quark tensor currents in the pion at large squared momentum transfer Q{sup 2}. It turns out that certain form factors can be evaluated using collinear factorization, whereas others receive important contributions from the end-point regions of the longitudinal quark momenta in the pion. We derive simple analytic expressions for the dominant terms at high Q{sup 2} and illustrate them numerically.

  2. The transverse spin structure of the pion at short distances

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Markus [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Szymanowski, Lech [Soltan Inst. for Nuclear Studies, Warsaw (Poland); Ecole Polytechnique, CNRS, Palaiseau (France). Centre de Physique Theorique; Paris-Sud Univ., CNRS, Orsay (France). Lab. de Physique Theorique

    2010-03-15

    We study the form factors of the quark tensor currents in the pion at large squared momentum transfer Q{sup 2}. It turns out that certain form factors can be evaluated using collinear factorization, whereas others receive important contributions from the end-point regions of the longitudinal quark momenta in the pion. We derive simple analytic expressions for the dominant terms at high Q{sup 2} and illustrate them numerically. (orig.)

  3. Determination of the pion and kaon structure functions

    International Nuclear Information System (INIS)

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

    1980-01-01

    Quark structure functions have been extracted from low-p/sub T/ inclusive hadron production data for the pion and kaon with use of the recombination model. n/sup π/=1.0 +- 0.1 and n/sup K/=2.5 +- 0.6 is obtained, where n is the leading (1-x) power of the nonstrange--valence-quark distribution. Both the pion and kaon nonstrange--sea-quark functions have napprox. =3.5

  4. Nuclear critical opalescence, a precursor to pion condensation

    International Nuclear Information System (INIS)

    Ericson, M.; Delorme, J.

    1978-03-01

    It is shown that pion condensation in nuclei, a long range phenomenon, has a precursor in the disordered phase, the local ordering of spins which becomes of infinite range at the critical point. A new physical effect arising from this short range order is predicted, namely the enhancement of the static nuclear pion field near the critical momentum. This phenomenon is strongly reminiscent of the critical opalescence observed in the scattering of neutrons by antiferromagnetic subtances

  5. Nuclear critical opalescence, a precursor to pion condensation

    International Nuclear Information System (INIS)

    Ericson, M.; Delorme, J.

    1978-01-01

    It is shown that pion condensation in nuclei, a long-range phenomenon, has a precursor in the disordered phase, the local ordering of spins which becomes of infinite range at the critical point. A new physical effect arising from this short-range order is predicted, namely the enhancement of the static nuclear pion field near the critical momentum. This phenomenon is strongly reminiscent of the critical opalescence observed in the scattering of neutrons by antiferromagnetic substances. (Auth.)

  6. Pion-nucleon vertex function with one nucleon off shell

    International Nuclear Information System (INIS)

    Mizutani, T.; Rochus, P.

    1979-01-01

    The pion-nucleon vertex function with an off-mass-shell nucleon is obtained through sideways dispersion relations with the P 11 and S 11 pion-nucleon phase shifts as only input. Contrary to the recent calculation of Nutt and Shakin, we find that the proper and improper vertex functions behave quite differently, indicating the importance of the nucleon propagator dressing. In particular the proper vertex function is found to have two poles in the unphysical region

  7. Wavelength and coherence effects on the growth mechanism of silicon nanopillars and their use in the modification of spontaneous lifetime emission of BODIPY dye molecules

    Energy Technology Data Exchange (ETDEWEB)

    Acikgoz, Sabriye [Bogazici University, Department of Physics, Istanbul (Turkey); Karamanoglu Mehmetbey University, Department of Material Science and Engineering, Karaman (Turkey); Bilen, Bukem; Saygili, Asli C.; Aktas, Gulen; Inci, Mehmet Naci [Bogazici University, Department of Physics, Istanbul (Turkey); Sanyal, Amitav [Bogazici University, Department of Chemistry, Istanbul (Turkey)

    2012-09-15

    Silicon nanopillars are grown by an electrochemical anodization of p-type silicon wafers at low current densities in a hydrofluoric acid solution. CW, white light, and various UV pulsed lasers are employed as illumination sources in sample preparation to study wavelength and coherence effects on the growth mechanism of the nanopillars. Coherence is observed to be the foundation of regularity in obtaining conical shapes. The pillar size is found to be almost linearly proportional to the employed illumination wavelength during their growth. BODIPY dye molecules are chemically attached to these silicon nanopillars and the radiative decay rates are investigated by means of a time-resolved fluorescence experiment. The decay rate of the dye molecules embedded in the vicinity of various size pillar tips is significantly affected due to different apex angles of the conical nature. It is demonstrated that the pillar size and the separation between pillars can be adjusted if one uses a coherent light source with an appropriate wavelength during the course of fabrication process. Since change in the decay rate is due to tips of the pillars only, separation of a few micrometers between pillar tips allows one to directly monitor a dye, which is embedded to the tip of a single nanopillar, via a confocal microscopic method for the spontaneous lifetime measurements, without having needed to any extra efforts for an in situ imaging process. It is observed that as the pillar size gets smaller, the inhibition in the spontaneous lifetime of BODIPY is more pronounced. In addition, a more regular pillar structure yields nonvarying decay rates of the dye molecules throughout the silicon sample. (orig.)

  8. Gravitational wave from dark sector with dark pion

    Energy Technology Data Exchange (ETDEWEB)

    Tsumura, Koji [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Yamada, Masatoshi [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Yamaguchi, Yuya, E-mail: ko2@gauge.scphys.kyoto-u.ac.jp, E-mail: m.yamada@thphys.uni-heidelberg.de, E-mail: yy@particle.sci.hokudai.ac.jp [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2017-07-01

    In this work, we investigate the spectra of gravitational waves produced by chiral symmetry breaking in dark quantum chromodynamics (dQCD) sector. The dark pion (π) can be a dark matter candidate as weakly interacting massive particle (WIMP) or strongly interacting massive particle (SIMP). For a WIMP scenario, we introduce the dQCD sector coupled to the standard model (SM) sector with classical scale invariance and investigate the annihilation process of the dark pion via the 2π → 2 SM process. For a SIMP scenario, we investigate the 3π → 2π annihilation process of the dark pion as a SIMP using chiral perturbation theory. We find that in the WIMP scenario the gravitational wave background spectra can be observed by future space gravitational wave antennas. On the other hand, when the dark pion is the SIMP dark matter with the constraints for the chiral perturbative limit and pion-pion scattering cross section, the chiral phase transition becomes crossover and then the gravitational waves are not produced.

  9. Production and decay of baryonic resonances in pion induced reactions

    Directory of Open Access Journals (Sweden)

    Przygoda Witold

    2016-01-01

    Full Text Available Pion induced reactions give unique opportunities for an unambiguous description of baryonic resonances and their coupling channels. A systematic energy scan and high precision data, in conjunction with a partial wave analysis, allow for the study of the excitation function of the various contributions. A review of available world data unravels strong need for modern facilities delivering measurements with a pion beam. Recently, HADES collaboration collected data in pion-induced reactions on light (12C and heavy (74W nuclei at a beam momentum of 1.7 GeV/c dedicated to strangeness production. It was followed by a systematic scan at four different pion beam momenta (0.656, 0.69, 0.748 and 0.8 GeV/c in π− − p reaction in order to tackle the role of N(1520 resonance in conjunction with the intermediate ρ production. First results on exclusive channels with one pion (π− p and two pions (nπ+π−, pπ−π0 in the final state are discussed.

  10. The two-nucleon system above pion threshold

    International Nuclear Information System (INIS)

    Poepping, H.; Sauer, P.U.; Zhang Xizhen

    1987-01-01

    A force model is presented for the description of the two-nucleon system below and above pion threshold and its coupled inelastic channels with one pion. It uses Δ-isobar and pion degrees of freedom in addition to the nucleonic one. The force model is based on a hamiltonian approach within the framework of noncovariant quantum mechanics. It extends the traditional approach with purely nucleonic potentials in isospin-triplet partial waves. It is constructed to remain valid up to 500 MeV c.m. energy. The characteristics of the force model is its mechanism for pion production and pion absorption which is mediated by the Δ-isobar. Even without any fit of phenomenological parameters the force model is able to account for the experimental data of elastic nucleon-nucleon scattering' of the inelastic reactions pp ↔ π + d and of elastic pion-deuteron scattering with satisfactory accuracy. No need for the introduction of dibaryon degrees of freedom has been found yet. The force model is a realistic one in the two-nucleon system. In many-nucleon systems it forms the unifying basis for a microscopic description of nuclear structure and nuclear reactions at low and intermediate energies. (orig.)

  11. Interaction cross sections and pions minus multiplicities on nucleus-nucleus collisions at 4.2 GeV/c per nucleon

    International Nuclear Information System (INIS)

    Angelov, N.; Ahababyan, N.; Anoshin, A.I.

    1979-01-01

    Data are presented on inelastic cross sections and multiplicities of pions minus produced on collisions of protons, deuterons, helium-4 and carbon-12 nuclei at 4.2 GeV/c per nucleon in the propane bubble chamber witn tantalum and carbon plates. Average multiplicities and dispersions of multiplicity distributions are compared with those in nucleon-nucleon interactions. Deviation of C-Ta interaction data from universal dependence of dispersion on multiplicity is observed. Pion multiplicities are found proportional to the number of nucleons from incident nucleus which interacted in the target. The results are not in contradiction with the assumption that nucleons from the incident nucleus interact independently in the target. For C-Ta interactions the average radius of the pion emission volume has been determined by the interference method to be r=(3.3+-0.6) fm

  12. Coherent γ-ray production

    International Nuclear Information System (INIS)

    Bertolotti, M.; Sibilia, C.

    1985-01-01

    In this article the authors discuss a new approach for developing a coherent source of γ-rays. They offer a completely different scheme for development of the source that should overcome most of the problems encountered in ''classical γ-ray lasers,'' and in which the use of inverse Compton scattering of laser radiation onto a relativistic electron beam is made. This kind of interaction has been used to obtain γ-ray photons with good polarization and monochromaticity properties. The authors describe a new geometry of interaction which allows one to obtain coherent emission

  13. Pion inelastic scattering, pion photoproduction and inelastic electron scattering on light nuclei

    International Nuclear Information System (INIS)

    Ehramzhyan, R.A.

    1985-01-01

    Partial transitions in pion photoproduction reaction on 6 Li, 10 B, 12 C nuclei are considered. Particular stress is paied to simultaneous analysis both of (γ, π) ad (e, e'), (π, π') reactions. Such analysis is concretely ixemplified with the use of both phenomenological and microscopic approaches. Microscopic analysis is shown to give correct representation of reaction mechanism (γ, π), (e, e') and (π, π') at intermediate energies. Spin-isospin dipole resonances in 1p-shell nuclei are considered. It is shown that nuclear system excitation spectrum gross-structure is a result of resonance configuration splitting

  14. Effect of pion external distortion on low energy pion double-charge-exchange

    International Nuclear Information System (INIS)

    Khankhasaev, M.Kh.; Kurmanov, Zh.B.; Johnson, M.B.

    1993-01-01

    The effects of the external pion distortion for iso-elastic charge exchange scattering (within the framework of the isospin invariant optical model) is considered. An approximated method of taking into account the distortion based on the separable expansion of the optical potential in momentum space is developed. The result of external distortions for sequential scattering 14 C(π + , π - ) 14 O at 50 MeV is presented. It is shown that this distortion gives a small enhancement to forward and reduced the differential cross sections at large angels. 22 refs., 5 figs., 1 tab

  15. Pion scattering from very light nuclei

    International Nuclear Information System (INIS)

    Berman, B.

    1993-01-01

    Selected recent elastic and inelastic pion-scattering experiments on 3 H, 3 He, and 4 He will be reviewed. Particular attention will be given to multinucleon or cluster aspects of the data, and to possible comparisons with electron-scattering results. From elastic scattering from 3 H and 3 He at forward angles, one can extract the matter distribution of the paired neutrons in 3 H as well as that of the paired protons in 3 He. At backward angles, scattering from correlated nucleon pairs and/or two-step processes play an important role. For inelastic scattering, the momentum-transfer dependence of the cross section varies strongly with incident energy. Elastic scattering from a polarized 3 He target shows a strong asymmetry near 90 degrees. Elastic scattering from 4 He yields results which cannot be fitted with a simple optical model. An for inelastic scattering from 4 He, analysis of the data requires an important contribution from direct triton knockout

  16. Phi meson production in pion proton interaction

    International Nuclear Information System (INIS)

    Makdisi, Y.I.

    1976-01-01

    The production of the phi meson and its decay mode into K + K - was investigated in a π - p → phi n reaction using a double arm effective mass spectrometer. Multiwire proportional chambers were deployed as particle detectors and a magnet provided momentum identification. Total cross sections were measured to be 18.5 +- 6, 24.1 +- 7, 25.1 +- 8.2 and 21.3 +- 7 μb for pion beam momenta of 1.6, 1.7, 1.8, and 2.0 GeV√c respectively and an upper limit of 15 μb was set for the 2.2 GeV/c point. These results coupled with other experiments done at higher energies show a strong energy dependence for this production process. Differential cross sections dsigma/dΩ were measured and cos THETA distributions in the center of mass system were consistent with isotropic production implying a flat differential cross section with respect to t. Although the statistics were quite an improvement on previous data they did not permit a thorough investigation of the decay density matrix elements. However, decay angular distributions in the Gottfried-Jackson frame were also presented

  17. Relativistic quantum kinetic analysis of a pion--nucleon system

    International Nuclear Information System (INIS)

    Alonso, J.D.

    1985-01-01

    A relativistic plasma of nucleons interacting through pions via the usual isospin-invariant Yukawa coupling is analyzed in the framework of the covariant Wigner function technique. The method is manifestly covariant and the temperature effects are considered. The relativistic quantum BBGKY hierarchy for the pion--nucleon system is derived. By generalizing the Bogolioubov analysis of the classical BBGKY hierarchy a non-perturbative renormalizable method is elaborated which allows the solution of the kinetic problem in form of power series of two cluster parameters which measure the importance of correlations. In the lowest order of the cluster expansion (Hartree approximation of zero-order approximation) the quasi-nucleon Fock space is introduced, the fermion Wigner function in the thermodynamic equilibrium is obtained and the vacuum effects are renormalized. In this approximation the plasma behaves as a perfect Fermi gas of nucleons and antinucleons, but there exists an abnormal configuration with a uniform pion condensate which is unstable. In the next approximation (quadratic in the small parameters) the quasi-pion dispersion relation is obtained and the vacuum polarization tensor is renormalized. The quasi-pion rest-mass spectra (''plasma frequency'') and the effective-coupling behaviour as functions of the thermodynamic state are given. By estimating the size of the cluster parameters the self-consistency of the approximation scheme is proved. The quasi-pion Fock space is introduced and the quasi-pion equilibrium Wigner function is obtained. From these results the problem of the higher-order corrections to the Hartree thermodynamics is outlined

  18. Baryonic 3P2-dominant superfluidity under combined pion condensation with Δ isobar. II). Properties of pairing interaction and numerical results

    International Nuclear Information System (INIS)

    Tamagaki, Ryozo

    2007-01-01

    -mixing provides the additional pairing attraction of short range, although the attenuation of the pairing attraction due to the charged-pion condensation comes about in the whole interaction range. This means that the superfluid of this type can provide the meaningful suppression on the emissivity of the pion direct Urca process, which makes the pion cooling scenario of neutron stars available. (author)

  19. Baryonic 3 P2-Dominant Superfluidity under Combined Pion Condensation with Δ Isobar. II --- Properties of Pairing Interaction and Numerical Results ---

    Science.gov (United States)

    Tamagaki, R.; Takatsuka, T.

    2007-05-01

    Delta-mixing provides the additional pairing attraction of short range, although the attenuation of the pairing attraction due to the charged-pion condensation comes about in the whole interaction range. This means that the superfluid of this type can provide the meaningful suppression on the emissivity of the pion direct Urca process, which makes the pion cooling scenario of neutron stars available.

  20. Experimental study of the pion-xenon nucleus collisions without particle production at 3.5 GeV/c momentum: general data

    International Nuclear Information System (INIS)

    Strugalski, Z.; Pavlak, T.; Pluta, J.

    1982-01-01

    There exist pion-xenon nucleus collision events in which intensive emission of fast protons, of kinetic energy of about 20-400 MeV, is observed only without particle production. Energy, momentum and angular distributions of the emitted protons are presented and analysed in classes of events with various proton emission intensity. It is concluded that: a)the nucleon emission proceeds independently of the particle production process; b)the observed intensive emission of the ''fast'' protons cannot be treated as a result of a simple knocking-out of the nucleons from the target by the incident hadron

  1. The PIOTRON: initial performance, preparation and experience with pion therapy

    International Nuclear Information System (INIS)

    Von Essen, C.F.; Blattmann, H.; Crawford, J.F.; Fessenden, P.; Pedroni, E.; Perret, C.; Salzmann, M.; Shortt, K.; Walder, E.

    1982-01-01

    The PIOTRON is a large solid angle superconducting channel built for the use of negative pi-mesons in radiotherapy. The pions are produced by protons of 590 MeV striking a target of molybdenum or beryllium. The pions are divided into 60 channels and deflected twice to enter the treatment volume radially. The momentum and the momentum band for all 60 channels can be chosen and the beam spot of Bragg peak pions at the isocenter of the applicator is a few centimeters in each direction. Dynamic scanning can thus achieve 3-dimensionally shaped treatment volumes. Two different methods are available: the ring scan, using changes of pion range; and the spot scan, involving translation of the patient through the fixed beam spot. Dose distributions of individual and multiple beams were plotted in a cylindrical water phantom. Radiobiological experiments with mammalian cells in gel and with mouse feet were performed. A special beam geometry using a sector of 15 beams was selected for the first treatments of patients with metastatic skin nodules. Six patients were treated. Acute skin reactions were scored and compared with those from orthovoltage therapy with comparable beam geometry. The RBE for 10 fractions is between 1.4 and 1.5. The next step involved treatment of patients inside water-bolus rings in preparation for dynamic therapy. Patients were then treated with the spot scan dynamic mode in the water bolus. The initial responses and reactions are favorable and confirm the feasibility and accuracy of dynamic pion therapy

  2. Chiral symmetry breaking and the pion quark structure

    International Nuclear Information System (INIS)

    Bernard, V.

    1986-01-01

    The mechanism of dynamical breaking of chiral symmetry in hadronic matter is first studied in the framework of the Nambu and Jona-Lasinio model on one hand and its generalisation to finite hadron size on the other hand. The analysis uses a variational procedure modelled after the BCS superconductor. Our study indicates for example, a great sensitivity of various quantities characterizing the breaking of symmetry to the shape of the interaction. Also the mechanism of breaking of chiral symmetry is essentially related to the mechanism of confinement. When a symmetry is spontaneously broken, there exists a Goldstone particle of zero mass. This is true in our model. This particle, the pion, is obtained as solution of a Bethe Salpeter equation for a qantiq bound state. This enables us to establish a connection between the pion as a Goldstone boson related to spontaneous symmetry breaking and the quark-antiquark structure of the pion. The finite mass of the physical pion is obtained with non zero current quark mass. Various properties of this particle are then studied in the RPA formalism. One important point of our model is the highly collective character of the pion. 85 refs [fr

  3. Dynamical pion production via parametric resonance from disoriented chiral condensates

    Science.gov (United States)

    Hiro-Oka, Hideaki; Minakata, Hisakazu

    2000-04-01

    We discuss a dynamical mechanism of pion production from disoriented chiral condensates. It leads to an explosive production of pions via the parametric resonance mechanism, which is similar to the reheating mechanism in inflationary cosmology. Classically it is related with the instability in the solutions of the Mathieu equation and we explore the quantum aspects of the mechanism. We show that nonlinearities and back reactions can be ignorable for a sufficiently long time under the small amplitude approximations of background σ oscillations, which may be appropriate for the late stage of a nonequilibrium phase transition. It allows us to obtain an explicit quantum state of the produced pions and σ, the squeezed state of BCS type. Single particle distributions and two pion correlation functions are computed within these approximations. The results obtained illuminate the characteristic features of multipion states produced through the parametric amplification mechanism. In particular, two pion correlations of various charge combinations contain back-to-back correlations which cannot be masked by the identical particle interference effect. We suggest that the parametric resonance mechanism might be a cause of the long lasting amplification of low-momentum modes in linear sigma model simulations.

  4. Nonlinear effect of pion production in collisions of atomic nuclei

    International Nuclear Information System (INIS)

    Grin', Yu.T.

    1982-01-01

    The phenomenon of pion production in relativistic nucleon-nucleus and nucleus-nucleus interactions is investigated. The present experimental data are analyzed. It is shown that average multiplicity of pions in the (p, C), (C, C) collision reactions with the momentum p=4.2 GeV/cA and (p, Ar), (Ar, KCl) with the momentum p=2.3 GeV/cA non-linearly depends on the nucleon number. The calculated values of average multiplicity of negative pions per one nucleon of nucleus-pro ectile, probability of pion production and number of nucleon interactions for the investigated reactions are presented as a table. A comparative analysis of average multiplicities of pions per nucleon-participant in the nucleon-nucleus and nucleus-nucleus reactions at the p=2.3 GeV/cA momentum for argon and at the p=4.2 GeV/cA for carbon reveals that decrease of multiplicity by 30-35% is observed in nucleus-nucleus collision. Non-linearity is associated with decrease of effective interaction of each incident nucleon in the collision of nuclei as compared with the number of nucleon interactions in the ''elementary'' nucleon-nucleus reaction. Knock-out of nucleons from the colliding nuclei is the most probable reason for the decrease of the number of interactions

  5. Basic features of the pion valence-quark distribution function

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Lei [CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005 (Australia); Mezrag, Cédric; Moutarde, Hervé [Centre de Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette (France); Roberts, Craig D. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Rodríguez-Quintero, Jose [Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, Huelva E-21071 (Spain); Tandy, Peter C. [Center for Nuclear Research, Department of Physics, Kent State University, Kent, OH 44242 (United States)

    2014-10-07

    The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables a realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, q{sup π}(x); namely, at a characteristic hadronic scale, q{sup π}(x)∼(1−x){sup 2} for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.

  6. Incorporating pion effects into the naive quark model

    International Nuclear Information System (INIS)

    Nogami, Y.; Ohtuska, N.

    1982-01-01

    A hybrid of the naive nonrelativistic quark model and the Chew-Low model is proposed. The pion is treated as an elementary particle which interacts with the ''bare baryon'' or ''baryon core'' via the Chew-Low interaction. The baryon core, which is the source of the pion interaction, is described by the naive nonrelativistic quark model. It turns out that the baryon-core radius has to be as large as 0.8 fm, and consequently the cutoff momentum Λ for the pion interaction is < or approx. =3m/sub π/, m/sub π/ being the pion mass. Because of this small Λ (as compared with Λapprox. nucleon mass in the old Chew-Low model) the effects of the pion cloud are strongly suppressed. The baryon masses, baryon magnetic moments, and the nucleon charge radii can be reproduced quite well. However, we found it singularly difficult to fit the axial-vector weak decay constant g/sub A/

  7. The bag model and the Nambu-Goldstone pion

    International Nuclear Information System (INIS)

    Lee, H.C.; Ho-Kim, Q.

    1983-01-01

    The MIT bag model for the pion is improved and extended in such a way that the pion does not have spurious center-of-mass motions; perturbative gluon contributions to the pion mass msub(π) and decay constant fsub(π) are both calculated to lowest order in αsub(s). The pion is a Nambu-Goldstone boson in the sense that the vacuum in the bag refers to massive constituent quarks, but not so massless current quarks. The transformation of Nambu and Jona-Lasinio between massive and massless quarks is utilized in the computation of fsub(π), the result of which strongly suggests that quarks in the pion are correlated, characterized by a correlation momentum which is proportional 300 MeV/c. The vacuum expectation value for the massless quark condensate is calculated to be proportional0.04 GeV 3 , corresponding to a current quark mass of proportional4 MeV. The requirement that msub(π) approaches zero in a manner consistent with PCAC constrains the bag energy to be msub(π)/4. (orig.)

  8. Distortion of two-pion interferometry by multipion correlations

    International Nuclear Information System (INIS)

    Zhang, W.N.; Liu, Y.M.; Wang, S.; Liu, Q.J.; Jiang, J.; Keane, D.; Shao, Y.; Chu, S.Y.; Fung, S.Y.

    1993-01-01

    Multipion correlations arising from the symmetrization of the n-pion wave function affect the extracted information from two-pion correlation measurements. The influence of multipion correlations on a sample of like-pion pairs can be expressed as a multipion correlation factor, the distribution of which offers good sensitivity to the multipion correlation effect. Analyses of the multipion correlation factor for two Bevalac streamer chamber data samples of 2.1A GeV Ne+Pb and 1.8A GeV Ar+Pb collisions show that the multipion correlation effect in the former sample is greater than in the latter. This result mainly arises from the fact that the pion source for Ne projectiles is smaller than for Ar projectiles. The residual correlations in the reference sample are related to the multipion correlation factor in multipion events, which can be expressed as a residual correlation factor. The influence of multipion correlations on two-pion interferometry analyses arises from the ratio of the residual correlation factor to the multipion correlation factor

  9. Experimental study on pion capture by hydrogen bound in molecules

    International Nuclear Information System (INIS)

    Horvath, D.; Aniol, K.A.; Entezami, F.; Measday, D.F.; Noble, A.J.; Stanislaus, S.; Virtue, C.J.

    1988-08-01

    An experiment was performed at TRIUMF to study the formation of pionic hydrogen atoms and molecules in solids, particularly in groups of organic molecules of slightly different structure in order to help further clarify the problem. The nuclear capture of pions by hydrogen was measured using the charge exchange of stopped pions. The coincident photons emitted by the decaying π 0 mesons were detected by TRIUMF's two large NaI spectrometers. New experimental results were obtained for the capture probability of stopped π - mesons in the nuclei of hydrogen atoms, chemically bound in molecules of some simple hydrides, acid anhydrides, and sugar isomers. A linear relation was found between pion capture in hydrogen and melting point in sugar isomers. The pion capture probability in acid anhydrides is fairly well described by a simple atomic capture model in which the capture probability on the hydrogen dramatically increases as the hydrogen atom is separated from the strongly electronegative C 2 O 3 group. Both effects are consistent with a correlation between pion capture and electron density on hydrogen atoms. (Author) (38 refs., 4 tabs., 7 figs.)

  10. Study on Charged Top-Pion Decay Processes

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-Lei; XU Wen-Na; DU Lin-Lin

    2004-01-01

    In the framework of top-color assisted technicolor (TC2) theory, we study the four decay processes of charged top-pion, i.e., П+t → t-b, П+t → c-b, П+t → W+γ П+t → W+ Z0. The decay branching ratio of these modes are calculated. The results show that the main decay channels of charged top-pion are the tree level modes: П+t → t-b and П+t → c-b. Light П+t is easier to be detected than heavy one at future coliders. So, the study provides us with some useful informations to search for charged top-pion.

  11. The quasi deuteron model for low energy pion absorption

    International Nuclear Information System (INIS)

    Gouweloos, M.

    1986-01-01

    In this thesis pion absorption in complex nuclei is studied in the quasi-deuteron model in which the pion is absorbed on a nucleon pair in the nucleus. The mechanism is studied in the low-energy domain since then the in-medium (pi→NN) operator turns out to be of simple character. In Ch. 2 and 3 this operator is constructed and analytical expressions are derived for (pi,NN) distributions in a plane wave impulse approximation for nuclei. The results turn out to be very useful for developing insight in the possibilities inherent in the QDM and the interpretation of the results in later chapters. Ch. 4 to 6 are devoted to the more realistic distorted wave calculations. In Ch. 4 the formal framework is presented and the calculational details are discussed. Ch.5 and 6 contain the comparison to stopped pion and in-flight data respectively. In Ch. 7 the main results are summarized. (Auth.)

  12. Measurement of the charged pion polarizability at COMPASS

    International Nuclear Information System (INIS)

    Nagel, Thiemo Christian Ingo

    2012-01-01

    The reaction π - +Z→π - +γ+Z in which a photon is produced by a beam pion scattering off a quasi-real photon of the Coulomb field of the target nucleus is identified experimentally by the tiny magnitude of the momentum transfer to the nucleus. This process gives access to the charged pion polarizabilities α π and β π whose experimental determination constitutes an important test of Chiral Perturbation Theory. In this work, the pion polarizability is obtained as α π =(1.9±0.7 stat. ±0.8 syst. ) x 10 -4 fm 3 from data taken with 190 GeV/c hadron beam provided by SPS to the COMPASS experiment at CERN in November 2009 and under the assumption of α π +β π =0.

  13. QCD-based pion distribution amplitudes confronting experimental data

    International Nuclear Information System (INIS)

    Bakulev, A.P.; Mikhajlov, S.V.; Stefanis, N.G.

    2001-01-01

    We use QCD sum rules with nonlocal condensates to recalculate more accurately the moments and their confidence intervals of the twist-2 pion distribution amplitude including radiative corrections. We are thus able to construct an admissible set of pion distribution amplitudes which define a reliability region in the a 2 , a 4 plane of the Gegenbauer polynomial expansion coefficients. We emphasize that models like that of Chernyak and Zhitnitsky, as well as the asymptotic solution, are excluded from this set. We show that the determined a 2 , a 4 region strongly overlaps with that extracted from the CLEO data by Schmedding and Yakovlev and that this region is also not far from the results of the first direct measurement of the pion valence quark momentum distribution by the Fermilab E791 collaboration. Comparisons with recent lattice calculations and instanton-based models are briefly discussed

  14. Pion production in relativistic collisions of nuclear drops

    International Nuclear Information System (INIS)

    Alonso, C.T.; Wilson, J.R.; McAbee, T.L.; Zingman, J.A.

    1988-09-01

    In a continuation of the long-standing effort of the nuclear physics community to model atomic nuclei as droplets of a specialized nuclear fluid, we have developed a hydrodynamic model for simulating the collisions of heavy nuclei at relativistic speeds. Our model couples ideal relativistic hydrodynamics with a new Monte Carlo treatment of dynamic pion production and tracking. The collective flow for low-energy (200 MeV/N) collisions predicted by this model compares favorably with results from earlier hydrodynamic calculations which used quite different numerical techniques. Our pion predictions at these lower energies appear to differ, however, from the experimental data on pion multiplicities. In this case of ultra-relativistic (200 GeV/N) collisions, our hydrodynamic model has produced baryonic matter distributions which are in reasonable agreement with recent experimental data. These results may shed some light on the sensitivity of relativistic collision data to the nuclear equation of state. 20 refs., 12 figs

  15. Pion-Skyrmion scattering: collective coordinates at work

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1985-06-01

    It is argued that the Skryme model, and more generally, the picture of the nucleon as a chiral soliton, can give a qualitatively correct picture of pion-nucleon scattering, considering both group-theoretic and more scheme-dependent results. The properties of the nucleon and its excited states in large-N quantum chromodynamics are discussed qualitatively. Then the pion-nucleon S-matrix is reduced. It is found that the model succeeds at the first level of calculation in producing many of the features of pion-nucleon scattering which are revealed by experiment, but that many aspects of the description need to be better understood, including the treatment of nonleading corrections near threshold and the inclusion of inelastic channels. 22 refs., 8 figs

  16. Comparison of pion- and proton-production of charmonium

    International Nuclear Information System (INIS)

    Graff, T.L.

    1984-01-01

    Charomium chi states produced in π - -beryllium interactions at 190 GeV/c and in proton-beryllium interactions at 200 GeV/c and 250 GeV/c have been observed via their decay into J/Psi + γ. This experiment was carried out with the Chicago Cyclotron Magnet Spectrometer at Fermilab. The fraction of J/Psi's resulting from chi decay is measured to be 0.33 +- 0.07 for incident pions and 0.47 +- 0.21 for incident protons. The chi(3510) and chi(3555) are produced in roughly equal numbers for pions, but the chi(3555) dominates for protons. Simple gluon fusion accounts for chi production by protons. This is reasonable considering the lack of valence antiquarks in the proton-beryllium system. Other mechanisms are needed to explain chi production by pions

  17. Dynamical chiral symmetry breaking and pion decay constant

    International Nuclear Information System (INIS)

    Gogohia, V.Sh.; Kluge, Gy.

    1991-08-01

    Flavour non-singlet, chiral axial-vector Ward-Takahashi identity is investigated in the framework of dynamical chiral symmetry breaking. The use of the condition of stationarity for the bound-state amplitude is proposed in order to fully determine this quantity and the regular piece of the corresponding axial vertex. This makes it possible to express the pion decay constant in terms of the quark propagator variables only. An exact expression was found for the pion decay constant in current algebra and in Jackiw-Johnson representation as well. We also find a new expression for the pion decay constant in the Pagels-Stokar-Cornwall variables within the framework of Jackiw-Johnson representation. (author) 22 refs.; 2 figs

  18. Conformal symmetry and pion form factor: Soft and hard contributions

    International Nuclear Information System (INIS)

    Choi, Ho-Meoyng; Ji, Chueng-Ryong

    2006-01-01

    We discuss a constraint of conformal symmetry in the analysis of the pion form factor. The usual power-law behavior of the form factor obtained in the perturbative QCD analysis can also be attained by taking negligible quark masses in the nonperturbative quark model analysis, confirming the recent AdS/CFT correspondence. We analyze the transition from soft to hard contributions in the pion form factor considering a momentum-dependent dynamical quark mass from an appreciable constituent quark mass at low momentum region to a negligible current quark mass at high momentum region. We find a correlation between the shape of nonperturbative quark distribution amplitude and the amount of soft and hard contributions to the pion form factor

  19. Measurement of the charged pion polarizability at COMPASS

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, Thiemo Christian Ingo

    2012-09-26

    The reaction {pi}{sup -}+Z{yields}{pi}{sup -}+{gamma}+Z in which a photon is produced by a beam pion scattering off a quasi-real photon of the Coulomb field of the target nucleus is identified experimentally by the tiny magnitude of the momentum transfer to the nucleus. This process gives access to the charged pion polarizabilities {alpha}{sub {pi}} and {beta}{sub {pi}} whose experimental determination constitutes an important test of Chiral Perturbation Theory. In this work, the pion polarizability is obtained as {alpha}{sub {pi}}=(1.9{+-}0.7{sub stat.}{+-}0.8{sub syst.}) x 10{sup -4} fm{sup 3} from data taken with 190 GeV/c hadron beam provided by SPS to the COMPASS experiment at CERN in November 2009 and under the assumption of {alpha}{sub {pi}}+{beta}{sub {pi}}=0.

  20. The CHAOS spectrometer for pion physics at TRIUMF

    International Nuclear Information System (INIS)

    Smith, G.R.; Amaudruz, P.A.; Brack, J.T.

    1994-12-01

    The Canadian high acceptance orbit spectrometer (CHAOS) is a unique magnetic spectrometer system recently commissioned for studies of pion induced reactions at TRIUMF. It is based on a cylindrical dipole magnet producing vertical magnetic fields up to 1.6 T. The scattering target is located in the center of the magnet. Charged particle tracks produced by pion interactions there are identified using four concentric cylindrical wire chambers surrounding the target. Particle identification and track multiplicity are determined by cylindrical layers of scintillation counters and lead glass Cerenkov counters, which also provide a first level trigger. A sophisticated second level trigger system permits pion fluxes in excess of 5 MHz to be employed. The detector subtends 360 o in the horizontal plane, and ±7 o out of this plane for a solid angle coverage approximately 10% of 4π sr. The momentum resolution delivered by the detector system is 1% (σ). (author). 16 refs., 12 figs

  1. Low-energy photo- and electroproduction for physical pions

    International Nuclear Information System (INIS)

    MacMullen, J.T.

    1979-02-01

    The background resonance Δ(1230), Nsup(*)(1520), Nsup(*)(1470) and Nsup(*)(1535)pion and axial-vector amplitudes are first calculated in the soft pion and on-shell configuration, respectively. Then a comparison is made with the usual soft pion theorems and on-shell low-energy expansions of current algebra as worked out in the previous paper. The agreement is good and we also deduce a nucleon dipole form factor axial-vector mass of msub(A)approximately equal to 1,23 GeV. Finally an approximate value for the non-strange current quark mass of m equal to 0,64 +- 1,11μ is extracted from the data

  2. Reggeon and pion contributions in exclusive diffractive processes at HERA

    International Nuclear Information System (INIS)

    Golec-Biernat, K.; Kwiecinski, J.; Szczurek, A.

    1997-01-01

    The contribution of subleading f 2 , ω, a 2 and ρ reggeons to the diffractive structure function F 2 D(3) (x P , β, Q 2 )are estimated. In addition we include the pion exchange which was recently found to be responsible for the violation of the Gottfried Sum Rule. The reggeon and pion contribution lead to a violation of the factorization of the diffractive structure function. The diffractive structure function is separated into the contributions with leading proton Δ (n) F 2 D /Δ (p) F 2 D as a function ox x P in the interval 10 -2 P -1 . The effect is due to the exchange of the isovector a 2 and ρ reggeons at smaller x P and the pion exchange at x P > 10 -2 . (author). 27 refs, 4 figs

  3. Relativistic generalizations of simple pion-nucleon models

    International Nuclear Information System (INIS)

    McLeod, R.J.; Ernst, D.J.

    1981-01-01

    A relativistic, partial wave N/D dispersion theory is developed for low energy pion-nucleon elastic scattering. The theory is simplified by treating crossing symmetry only to lowest order in the inverse nucleon mass. The coupling of elastic scattering to inelastic channels is included by taking the necessary inelasticity from experimental data. Three models are examined: pseudoscalar coupling of pions and nucleons, pseudovector coupling, and a model in which all intermediate antinucleons are projected out of the amplitude. The phase shifts in the dominant P 33 channel are quantitatively reproduced for P/sub lab/ 33 phase shifts. Thus a model of the pion-nucleon interaction which does not include antinucleon degrees of freedom is found to be unphysical

  4. Radiobiological work using a negative pion beam at the Rutherford Laboratory 1971-76

    International Nuclear Information System (INIS)

    Ellis, R.E.; Lindop, P.J.; Coggle, J.E.; Fraser, G.

    1976-08-01

    The subject is discussed in two sections: physics experiments (including, inter alia, dose measurement, LET distribution, radiation products of spallation); radiobiological studies (including separate reports as follows: review of experimental programme; some in vivo effects of negative pions in mice; survival and recovery of Hela cells in vitro; negative pion dose-response curves for frozen Hela cells; response of vicia faba to irradiation with negative pions; pion experiments with chromosome aberrations). (U.K.)

  5. Pion-nucleon vertex function and the Chew-Low model

    International Nuclear Information System (INIS)

    Nutt, W.T.

    1977-01-01

    We provide an interpretation of the cutoff function used in the Chew-Low theory of pion-nucleon scattering. It is shown that this function may be related to the pion-pion interaction which is not explicitly considered in the Chew-Low approach. Using a previously developed model for the pion-nucleon vertex function, we then perform a ''parameter-free'' Chew-Low calculation which predicts the P 33 resonance quite well

  6. PIGMI: a design report for Pion Generator for Medical Irradiations

    International Nuclear Information System (INIS)

    Hansborough, L.D.

    1981-09-01

    PIGMI (Pion Generator for Medical Irradiations) is an integrated linear accelerator (linac) system developed under the auspices of the National Cancer Institute for specific application to cancer treatment in a hospital environment. In its full configuration, PIGMI is a proton linac that is far smaller, less expensive, and more reliable than previous machines that produce pions. Subsets of PIGMI technology can be used with equal advantage to generate beams of other particles (such as neutrons, protons, or heavy ions) that may be of interest for radiotherapy, radioisotope production, or other applications. The dramatic performance and cost advantages of this new breed of acceleraor result from a number of improvements. In the low-energy portion of the machine, a new type of low-energy linac (the radio-frequency quadrupole[RFQ]) produces an exceptionally good quality beam, and uses a very simple 30-kV injector. In the second part of the machine (the drift-tube linac [DTL]), high accelerating gradients are now achievable with consequent reductions in machine length. Another new structure (the disk and washer [DAW]) will be used in the third and final section of the accelerator; this portion will also be relatively short and require few power amplifiers. The entire machine is designed for ease of operation and high reliability. The pion-production machine, discussed in this report, accelerates a 100-μA average proton-beam current to 650 MeV; use of an efficient pion-collection channel would result in an average pion flux of over 100 rad/min in a volume of about 1 l. Pion-channel design is not treated in this report. Accelerator construction cost is estimated at $10 million (1980 dollars); site preparation and treatment facility costs would bring the cost of a complete facility to an estimated $25 million

  7. Study of the Production of Single Pions in Pion-proton Collisions near Threshold

    CERN Multimedia

    2002-01-01

    This experiment aims at a complete-kinematics measurement of the processes @p|-p @A @p|-@p|+n and @p|+p @A @p|+@p|+n in the region of incident momenta between 300 MeV/c and 460 MeV/c. It uses the Omicron Spectrometer with detectors placed in the magnetic field close to a 12 atm. hydrogen gas target. The apparatus has an acceptance of 4\\% for the processes to be studied. \\\\ \\\\ Their threshold is at 279 MeV/c and pion production in this region is interesting from the point of view of the determination of transformation properties of the chiral-symmetry-breaking part of the Lagrangian.

  8. Capture and transfer of stopped pions in alcohols

    International Nuclear Information System (INIS)

    Harston, M.R.; Armstrong, D.S.; Measday, D.F.; Stanislaus, S.; Weber, P.; Horvath, D.

    1990-02-01

    The pion charge exchange probability in hydrogen for stopped π - has been measured for a series of alcohols. The relative atomic capture probabilities for hydrogen in different chemical environments as well as for the other molecular constituents were extracted from the data using a phenomenological approach. The results allow the prediction of the charge exchange probability in other molecules of similar chemical structure. The charge exchange probability in deuterated methanols was measured and compared to the prediction of our model. A comprehensive picture is obtained if pion transfer from hydrogen to deuterium is included

  9. Nonpartonic Effects in Pion Electroproduction in the Hermes Kinematical Region

    International Nuclear Information System (INIS)

    Uleshchenko, V.; Szczurek, A.

    2002-01-01

    The presentation is concerned with higher twist corrections of nonpartonic origin to semi-inclusive observables in the kinematical region relevant for the HERMES experiment. We demonstrate a strong impact of the VDM-like interaction and the exclusive production of ρ 0 meson on the extraction of the (anti)d - (anti)u asymmetry from charged pion DIS multiplicities. We also show that it is the exclusive- ρ 0 channel which accounts for the experimentally observed effect of the excess of charged over neutral pions produced at large z. (author)

  10. Critique of a pion exchange model for interquark forces

    International Nuclear Information System (INIS)

    Isgur, Nathan

    2000-01-01

    I describe four serious defects of a widely discussed pion exchange model for interquark forces: it does not solve the ''spin-orbit problem'' as advertised, it fails to describe the internal structure of baryon resonances, it leads to disastrous conclusions when extended to mesons, and it is not reasonably connected to the physics of heavy-light systems. While extensions of the original pion exchange model may be able to correct these defects, this catalogue of criticisms defines some of the most formidable problems such elaborations must address. (c) 2000 The American Physical Society

  11. Probing the 'nutcracker' by two-pion correlation

    International Nuclear Information System (INIS)

    Hirano, Tetsufumi; Morita, Kenji

    2001-01-01

    We investigate the 'nutcracker' phenomenon by studying two-pion correlation functions of non-central relativistic heavy-ion collisions. We apply the full (3+1)-dimensional hydro-dynamic model with first order phase transition. Based on numerical results which shows the 'nutcracked' freeze-out hypersurface, we calculate the two-pion correlation functions. In the case of snapshot hypersurfaces which clearly show the nut-shell structure, we find a interesting behavior at high relative momenta. We discuss the possibility of observing the phenomenon in heavy ion experiments. (author)

  12. Static model calculation of pion-nucleon scattering

    International Nuclear Information System (INIS)

    Itoh, Takashi

    1975-01-01

    The p-wave pion-nucleon scattering phase-shifts are computed by the Chew-Low static model for pion incident energy of 0-300 MeV. The square of the unrenormalized coupling constant is taken to be f 2 =0.2, and the cutoff is made at k sub(max)=6μ. The computed 3,3 phase-shift passes through 90 deg about at the right energy. The other phase-shifts computed are small in rough agreement with experiment. (auth.)

  13. Correlations and self-consistency in pion scattering. II

    International Nuclear Information System (INIS)

    Johnson, M.B.; Keister, B.D.

    1978-01-01

    In an attempt to overcome certain difficulties of summing higher order processes in pion multiple scattering theories, a new, systematic expansion for the interaction of a pion in nuclear matter is derived within the context of the Foldy-Walecka theory, incorporating nucleon-nucleon correlations and an idea of self-consistency. The first two orders in the expansion are evaluated as a function of the nonlocality range; the expansion appears to be rapidly converging, in contrast to expansion schemes previously examined. (Auth.)

  14. Tensor polarization in pion-deuteron elastic scattering

    International Nuclear Information System (INIS)

    Holt, R.J.

    1983-01-01

    The angular dependence of the tensor polarization t 20 /sup lab/ of recoiling deuterons in π-d elastic scattering was measured as a function of incident pion energy in the range 134 to 256 MeV. No evidence was found for rapid energy or angular dependences in t 20 /sup lab/. The results agree most favorably with theoretical calculations in which the P 11 π-N amplitude has been removed altogether. This agreement is consistent with a small effect of pion absorption on the elastic channel. 14 references

  15. Towards a dispersive determination of the pion transition form factor

    Science.gov (United States)

    Leupold, Stefan; Hoferichter, Martin; Kubis, Bastian; Niecknig, Franz; Schneider, Sebastian P.

    2018-01-01

    We start with a brief motivation why the pion transition form factor is interesting and, in particular, how it is related to the high-precision standard-model calculation of the gyromagnetic ratio of the muon. Then we report on the current status of our ongoing project to calculate the pion transition form factor using dispersion theory. Finally we present and discuss a wish list of experimental data that would help to improve the input for our calculations and/or to cross-check our results.

  16. Towards a dispersive determination of the pion transition form factor

    Directory of Open Access Journals (Sweden)

    Leupold Stefan

    2018-01-01

    Full Text Available We start with a brief motivation why the pion transition form factor is interesting and, in particular, how it is related to the high-precision standard-model calculation of the gyromagnetic ratio of the muon. Then we report on the current status of our ongoing project to calculate the pion transition form factor using dispersion theory. Finally we present and discuss a wish list of experimental data that would help to improve the input for our calculations and/or to cross-check our results.

  17. Can we get deeper inside the pion at the LHC?

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, V.A.; Ryutin, R.A.; Sobol, A.E. [Institute for High Energy Physics, Protvino (Russian Federation); Murray, M.J. [University of Kansas, Kansas City, KS (United States)

    2012-02-15

    We propose a measurement of leading neutrons spectra at LHC in order to extract inclusive {pi}{sup +} p and {pi}{sup +}{pi} {sup +} cross-sections with high p{sub T} jets production. The cross-sections for these processes are simulated with the use of parton distributions in hadrons. In this work we estimate the possibility to extract parton distributions in the pion from the data on these cross-sections and also search for signatures of fundamental differences in the pion and proton structure. (orig.)

  18. Inelastic pion scattering from 3H and 3He

    International Nuclear Information System (INIS)

    Berman, B.L.; Anderson, G.C.; Briscoe, W.J.; Mokhtari, A.; Petrov, A.M.; Sadler, M.E.; Barlow, D.B.; Nefkens, B.M.K.; Pillai, C.

    1995-01-01

    Cross sections have been measured for the inelastic scattering of π + and π - mesons from 3 H and 3 He in the 10-MeV interval just above the breakup thresholds, for incident pion energies of 142, 180, and 220 MeV and scattering angles of 40 degree, 60 degree, 80 degree, 90 degree, and 110 degree. No significant departure from unity is observed for the ratios of charge-symmetric cross sections. Comparisons are made with elastic pion-scattering and inelastic electron-scattering data

  19. Pion Photo- and Electroproduction and the Partially Conserved Axial Current

    International Nuclear Information System (INIS)

    Haberzettl, Helmut

    2000-01-01

    The relevance of the axial current for pion production processes off the nucleon with real or virtual photons is revisited. Employing the hypothesis of a partially conserved axial current (PCAC), it is shown that, when all of the relevant contributions are taken into account, PCAC does not provide any additional constraint for threshold production processes that goes beyond the Goldberger-Treiman relation. In particular, it is shown that pion electroproduction processes at threshold cannot be used to extract any information regarding the weak axial form factor. The relationships found in previous investigations are seen to be an accident of the approximations usually made in this context

  20. Evidence for delta-hole components from pion reactions

    International Nuclear Information System (INIS)

    Morris, C.L.

    1982-01-01

    Some anomalies observed in pion-induced reactions have been qualitatively explained with a model which includes Δ 3 3 admixtures in low lying nuclear states. Semi-quantitative analysis of these effects indicates the amplitudes for the Δ 3 3 admixtures necessary to explain these effects are on the order of a few percent. Although a more rigorous theoretical treatment of this problem is necessary, it appears that pion-induced reactions may provide a tool with which the spectroscopy of these Δ 3 3 -admixtures can be studied

  1. Measurement of the Charged Pion Electromagnetic Form Factor

    International Nuclear Information System (INIS)

    J. Volmer; David Abbott; H. Anklin; Chris Armstrong; John Arrington; K. Assamagan; Steven Avery; Oliver K. Baker; Henk Blok; C. Bochna; Ed Brash; Herbert Breuer; Nicholas Chant; Jim Dunne; Tom Eden; Rolf Ent; David Gaskell; Ron Gilman; Kenneth Gustafsson; Wendy Hinton; Garth Huber; Hal Jackson; Mark K. Jones; Cynthia Keppel; P.H. Kim; Wooyoung Kim; Andi Klein; Doug Koltenuk; Meme Liang; George Lolos; Allison Lung; David Mack; D. McKee; David Meekins; Joseph Mitchell; H. Mkrtchian; B. Mueller; Gabriel Niculescu; Ioana Niculescu; D. Pitz; D. Potterveld; Liming Qin; Juerg Reinhold; I.K. Shin; Stepan Stepanyan; V. Tadevosian; L.G. Tang; R.L.J. van der Meer; K. Vansyoc; D. Van Westrum; Bill Vulcan; Stephen Wood; Chen Yan; W.X. Zhao; Beni Zihlmann

    2001-01-01

    Separated longitudinal and transverse structure functions for the reaction 1H(e,eprime pi+)n were measured in the momentum transfer region Q2=0.6-1.6 (GeV/c)**2 at a value of the invariant mass W=1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parameterization fitted to very low Q2 elastic data

  2. Singular charge density at the center of the pion?

    International Nuclear Information System (INIS)

    Miller, Gerald A.

    2009-01-01

    We relate the three-dimensional infinite momentum frame spatial charge density of the pion to its electromagnetic form factor F π (Q 2 ). Diverse treatments of the measured form factor data including phenomenological fits, nonrelativistic quark models, the application of perturbative quantum chromodynamics (QCD), QCD sum rules, holographic QCD, and the Nambu-Jona-Lasinio (NJL) model all lead to the result that the charge density at the center of the pion has a logarithmic divergence. Relativistic constituent quark models do not display this singularity. Future measurements planned for larger values of Q 2 may determine whether or not a singularity actually occurs.

  3. Zero-degree injection line for PILAC, the proposed Los Alamos Pion Linac

    International Nuclear Information System (INIS)

    Blind, B.

    1991-01-01

    In this paper, an optimized injection line for PILAC, the proposed Los Alamos Pion Linac, is presented. With the other optimized components (pion source, accelerator, and high-resolution beamline and spectrometer), the system is capable of delivering 10 9 920-MeV pions per second to the target. 3 refs., 2 figs

  4. The Nonlinear Effects of Pion-Quark Coupling in the Cloudy Bag Model

    OpenAIRE

    Yasuhiko, FUTAMI; Satoru, AKIYAMA; Department of Physics, Faculty of Science and Technology Science University of Tokyo; Department of Physics, Faculty of Science and Technology Science University of Tokyo

    1990-01-01

    The nonlinear pion-quark interaction in the Cloudy Bag Model is investigated. The Hamiltonian is normal-ordered. The vacuum expectation value of pion field squared is evaluated by introducting some cutoff momentum for the virtual pions.We then calculate g_A, including other corrections.

  5. The nonlinear effects of pion-quark coupling in the Cloudy Bag Model

    International Nuclear Information System (INIS)

    Futami, Yasuhiko; Akiyama, Satoru

    1990-01-01

    The nonlinear pion-quark interaction in the Cloudy Bag Model is investigated. The Hamiltonian is normal-ordered. The vacuum expectation value of pion field squared is evaluated by introducing some cutoff momentum for the virtual pions. We then calculate g A , including other corrections. (author)

  6. Absorption of negative pions resting on nuclei of the 1p layer. Theoretical and experimental aspects

    International Nuclear Information System (INIS)

    Coupat, Bernard

    1981-01-01

    As the probability of capture of π- resting on 12 C with emission of a single proton which has been measured on the Saclay Linear Accelerator (ALS), is relatively high, it was obvious that this reaction type was based on a mechanism involving two nucleons. Due to the lack of theoretical interpretation for the emission of a single nucleon, a model has been developed in which the pion is absorbed by a correlated proton-proton pair, only one of these both protons being emitted. The first part of this research thesis addresses the calculation of absorption on a pair of nucleons with emission of these nucleons. It comprises the detailed presentation of the theoretical model, its comparison with other published calculations, and the comparison with results obtained by experiments of emission of nucleon pairs from carbon and oxygen. The second part proposes an overview of the great number of experimental results obtained by capture of π- resting on carbon. It reports the measurement of the emission of a single nucleon, the presentation of the elaborated theoretical model which has been developed to interpret this measurement. The author also compares the results of his calculation with the experimentally measured probability for the (π - p) process and the results published on the measurement of the (π - n).reaction [fr

  7. Fundamentals of Coherent Synchrotron Radiation in Storage Rings

    International Nuclear Information System (INIS)

    Sannibale, F.; Byrd, J.M.; Loftsdottir, A.; Martin, M.C.; Venturini, M.

    2004-01-01

    We present the fundamental concepts for producing stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The analysis includes distortion of bunch shape from the synchrotron radiation (SR), enhancing higher frequency coherent emission and limits to stable emission due to a microbunching instability excited by the SR. We use these concepts to optimize the performance of a source for CSR emission

  8. A coupled-channels analysis of pion scattering and pion-induced eta production on the nucleon

    International Nuclear Information System (INIS)

    Pratt, R.K.; Bennhold, C.; Surya, Y.

    1995-01-01

    Motivated by new, upcoming Brookhaven data, pion scattering and pion-induced eta production on the nucleon in the S 11 (1535) resonance region is studied in an extension of the unitary, relativistic resonance model by Surya and Gross. The Kernel of the relativistic wave equation includes the nucleon, Roper, δ(1232), D 13 (1520) and S 11 (1535) pole terms along with contact σ- and ρ-like exchange terms. The formalism includes a coupling between the πN and ηN channels. The resonance parameters are adjusted to reproduce the experimental πN phase shifts

  9. Analyses of multi-pion Hanbury Brown–Twiss correlations for the pion-emitting sources with Bose–Einstein condensation

    Science.gov (United States)

    Bary, Ghulam; Ru, Peng; Zhang, Wei-Ning

    2018-06-01

    We calculate the three- and four-particle correlations of identical pions in an evolving pion gas (EPG) model with Bose–Einstein condensation. The multi-pion correlation functions in the EPG model are analyzed in different momentum intervals and compared with the experimental data for Pb–Pb collisions at \\sqrt{{s}{NN}}=2.76 {TeV}. It is found that the multi-pion correlation functions and cumulant correlation functions are sensitive to the condensation fraction of the EPG sources in the low average transverse-momentum intervals of the three and four pions. The model results of the multi-pion correlations are consistent with the experimental data in a considerable degree, which gives a source condensation fraction between 16% and 47%.

  10. Possibility of investigation of pion degrees of freedom in atomic nuclei with the help of quasielastic pions knocking out by high energy electrons

    CERN Document Server

    Neudachin, V G; Sviridova, L L

    2002-01-01

    The attention is paid to the interesting possibilities of studying the pion degrees of freedom in the atomic nuclei by means of the quasielastic knocking out of pion (e, ep) from the nuclei by the electrons with the energy of several GeV. It appears, that the pulse distribution of the pions, knocked out from the separate nucleons and the nuclei, is in the whole differ essentially different

  11. Azimuthal correlations of pions in relativistic heavy ion collisions at 1 GeV/nucl

    International Nuclear Information System (INIS)

    Bass, S.A.; Hartnack, C.; Nantes Univ., 44; Stoecker, H.; Greiner, W.

    1995-01-01

    Triple differential cross sections of pions in heavy ion collisions at 1 GeV/nucl. are studied with the IQMD model. After discussing general properties of Δ resonance and pion production we focus an azimuthal correlations: At projectile- and target-rapidities we observe an anticorrelation in the in-plane transverse momentum between pions and protons. At c.m.-rapidity, however, we find that high p t pions are being preferentially emitted perpendicular to the event-plane. We investigate the causes of those correlations and their sensitivity on the density and momentum dependence of the real and imaginary part of the nucleon and pion optical potential. (orig.)

  12. Magnetic flux penetration and destruction of pion condensates

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, B J; Shepard, H K [New Hampshire Univ., Durham (USA). Dept. of Physics

    1976-08-30

    It is shown that an external magnetic field can destroy a pion condensate or lead to a vortex ground state similar to the mixed phase of a type II superconductor. Critical magnetic fields, determined for the ground state phases of the sigma model, are comparable to those which may be present in neutron stars.

  13. Renormalization of NN Interaction with Relativistic Chiral Two Pion Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Higa, R; Valderrama, M Pavon; Arriola, E Ruiz

    2007-06-14

    The renormalization of the NN interaction with the Chiral Two Pion Exchange Potential computed using relativistic baryon chiral perturbation theory is considered. The short distance singularity reduces the number of counter-terms to about a half as those in the heavy-baryon expansion. Phase shifts and deuteron properties are evaluated and a general overall agreement is observed.

  14. Critique of a pion exchange model for interquark forces

    International Nuclear Information System (INIS)

    Isgur, N.

    1999-01-01

    The author describes four serious defects of a widely discuss pion exchange model for interquark forces: it doesn't solve the ''spin-orbit problem'' as advertised, it fails to describe the internal structure of baryon resonances, it leads to disastrous conclusions when extended to mesons, and it is not reasonably connected to the physics of heavy-light systems

  15. Tests of the single-pion exchange model

    International Nuclear Information System (INIS)

    Treiman, S.B.; Yang, C.N.

    1983-01-01

    The single-pion exchange model (SPEM) of high-energy particle reactions provides an attractively simple picture of seemingly complex processes and has accordingly been much discussed in recent times. The purpose of this note is to call attention to the possibility of subjecting the model to certain tests precisely in the domain where the model stands the best chance of making sense

  16. Information on pion-nucleus optical potentials from elastic scattering

    International Nuclear Information System (INIS)

    Friedman, E.

    1983-02-01

    Data on the elastic scattering of pions by nuclei between 20 and 230 MeV is analyzed in an almost model-independent fashion. The real part of the potential, which is described by a bias-free Fourier-Bessel series, is found to have the typical Kisslinger or Laplacian-like shape between 30 and 80 MeV

  17. Pion linac as an energy-tagged ν source

    Directory of Open Access Journals (Sweden)

    T. Goldman

    2008-12-01

    Full Text Available The energy spectrum and flux of neutrinos from a linear pion accelerator are calculated analytically under the assumption of a uniform accelerating gradient. The energy of a neutrino from this source reacting in a detector can be determined from timing and event position information.

  18. Pion photo- and electroproduction in relativistic baryon ChPT

    Directory of Open Access Journals (Sweden)

    Tiator Lothar

    2014-06-01

    Full Text Available We present a calculation of pion photo- and electroproduction in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including order q4. We fix the low-energy constants by fitting experimental data in all available reaction channels. Our results can be accessed via a web interface, the so-called chiral MAID.

  19. Theory of the low-energy pion-nucleon interaction

    International Nuclear Information System (INIS)

    Banerjee, M.K.; Cammarata, J.B.

    1978-01-01

    A once-subtracted form of the Low equation for the pion-nucleon scattering amplitude is derived, with partial conservation of axial-vector current used to define the amplitude when one pion is off the mass shell. The static approximation is not made and both the seagull terms and the antinucleon contribution (z graphs) are retained. The theory is applied to calculate the S-wave amplitudes in the elastic scattering region. Good agreement is found with the phase shift fits to the data when we use vertical-barg/sub π/(4M 2 ) vertical-bar = 11.69 and 25.5 MeV for the πN sigma commutator. The implications of this work for the analysis of low-energy elastic scattering of pions form nuclei are discussed. In particular, we point out how this work establishes the presence of a Laplacian term in the pion-nucleus optical potential with a magnitude that is fixed from the value of the sigma commutator

  20. Utilization of pion production accelerators in biomedical applications

    International Nuclear Information System (INIS)

    Rosen, L.

    1979-01-01

    A discussion is presented of biomedical applications of pion-producing accelerators in a number of areas, but with emphasis on pion therapy for treatment of solid, non-metastasized malignancies. The problem of cancer management is described from the standpoint of the physicist, magnitude of the problem, and its social and economic impact. Barriers to successful treatment are identified, mainly with regard to radiation therapy. The properties and characteristics of π mesons, first postulated on purely theoretical grounds by H. Yukawa are described. It is shown how they can be used to treat human cancer and why they appear to have dramatic advantages over conventional forms of radiation by virtue of the fact that they permit localization of energy deposition, preferentially, in the tumor volume. The Clinton P. Anderson Meson Physics Facility (LAMPF), and its operating characteristics, are briefly described, with emphasis on the biomedical channel. The design of a relatively inexpensive accelerator specifically for pion therapy is described as is also the status of clinical trials using the existing Clinton P. Anderson Meson Physics Facility. The advantages of proton over electron accelerator for the production of high quality, high intensity negative pion beams suitable for radiation therapy of malignancies is also addressed. Other current, medically related applications of LAMPF technology are also discussed

  1. Pion-myon channeling in metals and semiconductors

    International Nuclear Information System (INIS)

    Rempp, H.

    1986-01-01

    The aim of the present thesis is the investigation of pions in several crystals under varying conditions. In chapter 2 channeling is outlined, in chapter 3 the method is described for μ + , chapter 4 presents the crystals used, chapters 5 and 6 measuring method and experiment. The results are compiled (chapter 7) and discussed (chapter 8). (BHO)

  2. Delta: the first pion nucleon resonance - its discovery and applications

    International Nuclear Information System (INIS)

    Nagle, D.E.

    1984-07-01

    It is attempted to recapture some of the fun and excitement of the pion-scattering work that led to the discovery of what is now called the delta particle. How significant this discovery was became apparent only gradually. That the delta is alive today and thriving at Los Alamos (as well as other places) is described

  3. Anomalous electrodynamics of neutral pion matter in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, Tomáš [Department of Mathematics and Natural Sciences, University of Stavanger,N-4036 Stavanger (Norway); Kadam, Saurabh V. [Indian Institute of Science Education and Research (IISER),Pune 411008 (India)

    2017-03-03

    The ground state of quantum chromodynamics in sufficiently strong external magnetic fields and at moderate baryon chemical potential is a chiral soliton lattice (CSL) of neutral pions https://arxiv.org/abs/1609.05213. We investigate the interplay between the CSL structure and dynamical electromagnetic fields. Our main result is that in presence of the CSL background, the two physical photon polarizations and the neutral pion mix, giving rise to two gapped excitations and one gapless mode with a nonrelativistic dispersion relation. The nature of this mode depends on the direction of its propagation, interpolating between a circularly polarized electromagnetic wave https://www.doi.org/10.1103/PhysRevD.93.085036 and a neutral pion surface wave, which in turn arises from the spontaneously broken translation invariance. Quite remarkably, there is a neutral-pion-like mode that remains gapped even in the chiral limit, in seeming contradiction to the Goldstone theorem. Finally, we have a first look at the effect of thermal fluctuations of the CSL, showing that even the soft nonrelativistic excitation does not lead to the Landau-Peierls instability. However, it leads to an anomalous contribution to pressure that scales with temperature and magnetic field as T{sup 5/2}(B/f{sub π}){sup 3/2}.

  4. Current algebra and soft pion theorems for weak π production

    International Nuclear Information System (INIS)

    Adler, S.L.

    1976-01-01

    Beginning with definitions of vector, scalar, axial vector, pseudoscalar, and tensor current densities, equal time current commutators are derived and divergences are discussed. The partially conserved axial current (PCAC) hypothesis is formulated and used to derive the Goldberger--Treiman relation. Current algebra and the PCAC hypothesis are then employed to develop a master formula describing the reaction J + N → π + N where J is a current with four momentum k, and π is a soft pion with four momentum q. Several applications are considered: πN scattering consistency conditions, π isovector electroproduction relations, π production by an isoscalar weak neutral current, π axial vector weak production relations, and low energy theorems which combine soft pion results with knowledge of divergences of the vector or axial vector current J (which induces weak pion production). It is concluded that (1) the entire weak production amplitude is determined to zero order in q by soft pion theorems, and (2) combined relations determine corrections linear in q but of zero order in k

  5. Quasi-pions with temperature dependent dispersion relation

    International Nuclear Information System (INIS)

    Gorenstein, M.I.

    1995-01-01

    We construct the procedure to calculate thermodynamical functions for a system of quasi-particles with temperature dependent dispersion relation. Two models for the hot quasi-pion system are considered to illustrate the importance of thermodynamical self consistency requirements. 8 refs., 9 figs

  6. Muon identification and pion rejection in the 4th concept

    Indian Academy of Sciences (India)

    The dual-solenoid magnetic field allows the reconstruction and precision momentum measurement of muons down to a few GeV (just the energy loss in the 10-int calorimeter and the coil) and the dual-readout calorimeter provides a new, unique and powerful separation of muons from pions. We use test beam data for the ...

  7. Measurement of the pion form factor at higher energies

    Energy Technology Data Exchange (ETDEWEB)

    Mack, D.J. [CEBAF, Newport News, VA (United States)

    1994-04-01

    One of the strongest arguments for increasing the nominal CEBAF beam energy to equal or exceed 6 GeV is that one would be able to make quality high Q{sup 2} measurements of the charged pion form factor.

  8. Distortion effects in pion-induced knock-out reactions

    International Nuclear Information System (INIS)

    Jain, B.K.

    The cross-section for (π + ,π + p) reaction on 12 C is calculated in DWIA at 100 and 180 MeV incident energy. The effect of pion distortion is found to be strong. Around 180 MeV the effect is strongly absorptive while around 10O MeV it is mainly dispersive. (auth.)

  9. Massive pions, anomalies and baryons in holographic QCD

    Energy Technology Data Exchange (ETDEWEB)

    Domenech, O. [Departament de Fisica and IFAE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Panico, G., E-mail: panico@phys.ethz.c [Institute for Theoretical Physics, ETH Zurich, 8093 Zurich (Switzerland); Wulzer, A. [Institut de Theorie des Phenomenes Physiques, EPFL, CH-1015 Lausanne (Switzerland)

    2011-03-01

    We consider a holographic model of QCD, obtained by a very simple modification of the original construction, which describes at the same time the pion mass, the QCD anomalies and the baryons as topological solitons. We study in detail its phenomenological implications in both the mesonic and baryonic sectors and compare with the observations.

  10. Resonance production and decay in pion induced collisions with HADES

    Directory of Open Access Journals (Sweden)

    Scozzi Federico

    2017-01-01

    Full Text Available The main goal of the High Acceptance Di-Electron experiment (HADES at GSI is the study of hadronic matter in the 1-3.5 GeV/nucleon incident energy range. HADES results on e+ e− production in proton-nucleus reactions and in nucleus-nucleus collisions demonstrate a strong enhancement of the dilepton yield relative to a reference spectrum obtained from elementary nucleon-nucleon reactions. These observations point to a strong modification of the in-medium ρ spectral function driven by the coupling of the ρ to baryon-resonance hole states. However, to scrutinize this conjecture, a precise study of the role of the ρ meson in electromagnetic baryon-resonance transitions in the time-like region is mandatory. In order to perform this study, HADES has started a dedicated pion-nucleon programme. For the first time a combined measurement of hadronic and dielectron final states have been performed in π−-N reactions at four different pion beam momenta (0.656, 0.69, 0.748 and 0.8 GeV/c. First results on exclusive channels with one pion π−-p and two pions (nπ+π−, pπ−π0 in the final state, which are currently analysed within the partial wave analysis (PWA framework of the Bonn-Gatchina group, are discussed. Finally first results for the dielectron analysis will be shown.

  11. The pion (muon) energy production cost in muon catalyzed fusion

    International Nuclear Information System (INIS)

    Fadeev, N.G.; Solov'ev, M.I.

    1995-01-01

    The article presents the main steps in the history of the study on the muon catalysis of nuclear fusion. The practical application of the muon catalysis phenomenon to obtain the energy gain is briefly discussed. The details of the problem to produce pion (muon) yield with minimal energy expenses have been considered. 31 refs., 4 tabs

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

    International Nuclear Information System (INIS)

    Breitschopf, J.

    2006-01-01

    This work describes the measurement of total SCX cross sections employing a new 4π scintillation counter to perform transmission measurements in the incident pion energy range from about 38 to 250 MeV. A small 4π detector box consisting of thin plastic scintillators has been constructed. The transmission technique, which was used, relates the number of transmitted charged pions to that of incident beam pions and this way effectively counts events with neutral products. The incoming negative pions were counted by three beam defining counters before they hit a target of very well known size and chemical composition. The target was placed in the box detector which was not sensitive to the neutral particles resulting from the SCX. The total cross section for emerging neutral particles was derived from the comparison of the numbers of the incoming and transmitted charged particles. The total SCX cross section on hydrogen was derived from the transmissions of a CH 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 Δ-resonance and the sp-interference region in one single experimental setup and improves the available data base for the SCX reaction. It is shown that the description of the SCX cross sections is improved if the s-wave amplitudes, that have been fixed essentially by elastic pion-nucleon scattering data, is reduced by (4±1.5)%. The exact value depends on the SCX literature data included and on the parameters of the Δ 0 Breit-Wigner resonance describing the p 33 -waves. This shows that p-wave as well as s-wave effects should be considered in studies of isospin symmetry breaking. Interestingly

  13. 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

  14. On the use of distributions of stopping pions as an indicator of the spatial distribution of the high-LET dose in negative pion radiotherapy

    International Nuclear Information System (INIS)

    Brenner, D.J.

    1991-01-01

    A semi-empirical across the treatment volume of a therapeutic negative pion beam. Such beams deliver dose partially at high LET (through alphas and heavier particles produced both directly in pion stars and via intermediate star-produced neutrons), and partially at low LET (through scattering of pions, electrons and muons, as well as protons produced directly from pion stars and via intermediate neutrons). The problem is how to understand the spatial distribution of the high-LET dose, which is responsible for the potentially improved biological response in the treatment volume

  15. Investigation of Compton effect on π-meson and charged pion polarizability

    International Nuclear Information System (INIS)

    Antipov, Yu.M.; Batarin, V.A.; Bezzubov, V.A.

    1986-01-01

    The results of an experiment aimed at the study of the 40 GeV/c pion radiative scattering on nuclei at small momentum transfers are presented. Compton effect on the pion was investigated and the charged pion polarizability was measured. The pion Compton-effect cross section dependence on the incident photon energy ω' 1 (rest pion frame) was measured in the 100 - 600 MeV range. The polarizability of charged pion from the analysis of Compton-effect events has been found to be β π =-α π =(-6.9 ± 1.4 stat. ± 1.2 syst. )x10 -43 cm 3 and the sun of pion electrical α π and magnetic β π polarizability has been estimated to be in agreement with theoretical predictions: α π +β π ≅ 0

  16. Bose-Einstein correlations of three charged pions in hadronic $Z^{0}$ decays

    CERN Document Server

    Ackerstaff, K; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Bartoldus, R; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bird, S D; Blobel, Volker; Bloodworth, Ian J; Bobinski, M; Bock, P; Böhme, J; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brown, R M; Burckhart, Helfried J; Burgard, C; Bürgin, R; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Davis, R; De Jong, S; del Pozo, L A; de Roeck, A; Desch, Klaus; Dienes, B; Dixit, M S; Doucet, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Eatough, D; Estabrooks, P G; Etzion, E; Evans, H G; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fischer, H M; Fleck, I; Folman, R; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon, J; Gascon-Shotkin, S M; Geich-Gimbel, C; Geralis, T; Giacomelli, G; Giacomelli, P; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Gross, E; Grunhaus, Jacob; Gruwé, M; Hanson, G G; Hansroul, M; Hapke, M; Hargrove, C K; Hartmann, C; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hillier, S J; Hobson, P R; Höcker, Andreas; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Joly, A; Jones, C R; Jovanovic, P; Junk, T R; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Koetke, D S; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kyberd, P; Lafferty, G D; Lanske, D; Lauber, J; Lautenschlager, S R; Lawson, I; Layter, J G; Lazic, D; Lee, A M; Lefebvre, E; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mannelli, M; Marcellini, S; Markopoulos, C; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Menke, S; Merritt, F S; Mes, H; Meyer, J; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mir, R; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nellen, B; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Oreglia, M J; Orito, S; Pálinkás, J; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poffenberger, P R; Poli, B; Polok, J; Przybycien, M B; Rembser, C; Rick, Hartmut; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharf, F; Scharff-Hansen, P; Schieck, J; Schmitt, B; Schmitt, S; Schöning, A; Schörner-Sadenius, T; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Sproston, M; Stahl, A; Stephens, K; Steuerer, J; Stoll, K; Strom, D; Ströhmer, R; Tafirout, R; Talbot, S D; Tanaka, S; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomson, M A; Von Törne, E; Torrence, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turcot, A S; Turner-Watson, M F; Van Kooten, R; Vannerem, P; Verzocchi, M; Vikas, P; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Yekutieli, G; Zacek, V; Zer-Zion, D

    1998-01-01

    Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 10^6 hadronic Z^0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r_3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of \\lambda_3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the \\lambda_3 value by 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.

  17. Virtual photons in the pion form factors and the energy-momentum tensor

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, Bastian E-mail: b.kubis@fz-juelich.de; Meissner, Ulf-G. E-mail: ulf-g.meissner@fz-juelich.de

    2000-05-22

    We evaluate the vector and scalar form factor of the pion in the presence of virtual photons at next-to-leading order in two-flavor chiral perturbation theory. We also consider the scalar and tensor pion form factors of the energy-momentum tensor. We find that the intrinsic electromagnetic corrections are very small for the vector as well as the charged pion scalar form factor. The scalar radius of the neutral pion is reduced by two percent. We perform infrared regularization by considering electron-positron annihilation into pions and the decay of a light Higgs boson into a pion pair. We discuss the detector resolution dependent contributions to the various form factors and pion radii.

  18. Virtual photons in the pion form factors and the energy-momentum tensor

    International Nuclear Information System (INIS)

    Kubis, Bastian; Meissner, Ulf-G.

    2000-01-01

    We evaluate the vector and scalar form factor of the pion in the presence of virtual photons at next-to-leading order in two-flavor chiral perturbation theory. We also consider the scalar and tensor pion form factors of the energy-momentum tensor. We find that the intrinsic electromagnetic corrections are very small for the vector as well as the charged pion scalar form factor. The scalar radius of the neutral pion is reduced by two percent. We perform infrared regularization by considering electron-positron annihilation into pions and the decay of a light Higgs boson into a pion pair. We discuss the detector resolution dependent contributions to the various form factors and pion radii

  19. Pion scattering to 8- stretched states in 60Ni

    International Nuclear Information System (INIS)

    Clausen, B.L.

    1988-03-01

    Using the Energetic Pion Channel and Spectrometer at the Los Alamos Meson Physics Facility, differential cross sections for pion scattering were measured for ten previously known J/sup π/ = 8/sup /minus// stretched states in 60 Ni. A possible new pure isoscalar stretched state was also found. The data were taken near the /DELTA//sub 3,3/-resonance using 162 MeV incident pions and scattering angles of 65/degree/, 80/degree/, and 90/degree/ for π + and 65/degree/ and 80/degree/ for π/sup /minus//. The analysis of the 60 Ni data found that the use of Woods-Saxon wave functions in the theoretical calculations gave much better agreement with data than the use of the usual harmonic oscillator wave functions. The WS theory gave better predictions of: the angle at which the π/sup /minus// and π + angular distributions are maximum, the ratios of π/sup /minus// to π + cross sections for pure isovector states (which were much larger than unity), and the absolute size of the cross sections for all states (so that the normalization factor necessary to arrive at agreement of theory with data was closer to unity). The theoretical calculations used the distorted wave impulse approximation, including new methods for unbound states. The sensitivities of the calculations to input parameters were investigated. This analysis using WS wave functions was extended to five other nuclei ( 12 C, 14 C, 16 O, 28 Si, and 54 Fe) on which both pion scattering and electron scattering have been done. A significant improvement in arriving at a normalization factor close to unity was found when WS wave functions were consistently used for analyzing both pion and electron inelastic scattering data. 101 refs., 26 figs., 13 tabs

  20. Measurement of charged pions in {sup 12}C+{sup 12}C collisions at 1A GeV and 2A GeV with HADES

    Energy Technology Data Exchange (ETDEWEB)

    Agakishiev, G.; Destefanis, M.; Gilardi, C.; Kirschner, D.; Kuehn, W.; Lange, J.S.; Metag, V.; Novotny, R.; Pechenov, V.; Pechenova, O.; Perez Cavalcanti, T.; Spataro, S.; Spruck, B. [Justus Liebig Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Agodi, C.; Coniglione, R.; Finocchiaro, P.; Maiolino, C.; Piattelli, P.; Sapienza, P. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Catania (Italy); Balanda, A.; Kozuch, A.; Przygoda, W. [Jagiellonian University of Cracow, Smoluchowski Institute of Physics, Krakow (Poland); Panstwowa Wyzsza Szkola Zawodowa, Nowy Sacz (Poland); Bellia, G. [Laboratori Nazionali del Sud, Istituto Nazionale di Fisica Nucleare, Catania (Italy); Universita di Catania, Dipartimento di Fisica e Astronomia, Catania (Italy); Belver, D.; Cabanelas, P.; Duran, I.; Garzon, J.A.; Lamas-Valverde, J.; Marin, J. [University of Santiago de Compostela, Departamento de Fisica de Particulas, Santiago de Compostela (Spain); Belyaev, A.; Chernenko, S.; Fateev, O.; Ierusalimov, A.; Zanevsky, Y. [Joint Institute of Nuclear Research, Dubna (Russian Federation); Bielcik, J.; Braun-Munzinger, P.; Galatyuk, T.; Gonzalez-Diaz, D.; Heinz, T.; Holzmann, R.; Koenig, I.; Koenig, W.; Kolb, B.W.; Lang, S.; Muench, M.; Palka, M.; Pietraszko, J.; Rustamov, A.; Schroeder, C.; Schwab, E.; Simon, R.S.; Traxler, M.; Yurevich, S.; Zumbruch, P. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Blanco, A.; Lopes, L.; Mangiarotti, A. [LIP-Laboratorio de Instrumentacao e Fisica Experimental de Particulas, Coimbra (Portugal); Bortolotti, A.; Michalska, B. [Sezione di Milano, Istituto Nazionale di Fisica Nucleare, Milano (Italy); Boyard, J.L.; Hennino, T.; Moriniere, E.; Ramstein, B.; Roy-Stephan, M.; Sudol, M. [CNRS/IN2P3 - Universite Paris Sud, Institut de Physique Nucleaire, Orsay Cedex (France); Christ, T.; Eberl, T.; Fabbietti, L.; Friese, J.; Gernhaeuser, R.; Jurkovic, M.; Kruecken, R. [and others

    2009-04-15

    We present the results of a study of charged-pion production in {sup 12}C+{sup 12}C collisions at incident beam energies of 1A GeV and 2A GeV using the HADES spectrometer at GSI. The main emphasis of the HADES program is on the dielectron signal from the early phase of the collision. Here, however, we discuss the data with respect to the emission of charged hadrons, specifically the production of {pi}{sup {+-}} mesons, which are related to neutral pions representing a dominant contribution to the dielectron yield. We have performed the first large-angular-range measurement of the distribution of {pi}{sup {+-}} mesons for the {sup 12}C+{sup 12}C collision system covering a fairly large rapidity interval. The pion yields, transverse-mass and angular distributions are compared with calculations done within a transport model, as well as with existing data from other experiments. The anisotropy of pion production is systematically analyzed. (orig.)

  1. Gross and Fine Structure of Pion Production Excitation Functions in {bold {ital p}}-Nucleus and Nucleus-Nucleus Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Jakobsson, B.; Berg, M.; Carlen, L.; Elmer, R.; Fokin, A.; Ghetti, R.; Martensson, J.; Noren, B.; Oskarsson, A.; Whitlow, H.J. [Department of Physics, University of Lund, Lund (Sweden); Ekstroem, C.; Ericsson, G.; Romanski, J.; van Veldhuizen, E.J.; Westerberg, L. [The Svedberg Laboratory and Department of Neutron Physics, University of Uppsala, Uppsala (Sweden); Julien, J. [Centre d`Etudes Nucleaires, Saclay (France); Skeppstedt, O. [Department of Physics, Chalmers Institute of Technology, Gothenburg (Sweden); Nyboe, K.; Thorsteinsen, T.F.; Amirelmi, S. [Department of Physics, University of Bergen, Bergen (Norway); Guttormsen, M.; Lo/vho/iden, G. [Department of Physics, University of Oslo, Oslo (Norway); Bellini, V.; Palazzolo, F.; Sperduto, M.L. [Istituto Nazionale di Fisica Nucleare/Laboratorio Nazionale del Sud, University of Catania, Catania (Italy); Bondorf, J.P.; Mishustin, I. [Niels Bohr Institute, Copenhagen (Denmark); Avdeichikov, V. [Joint Institute for Nuclear Research, Dubna (Russia); Lozhkin, O.V.; Murin, Y. [V.G. Khlopin Radium Institute, St.Petersburg (Russia)

    1997-05-01

    Slow ramping of the CELSIUS storage ring has been utilized to measure the yield of charged pions in proton and heavy ion induced collisions with continuously varying beam energy. Boltzmann-Uehling-Uhlenbeck predictions, including Fermi momenta of nucleons in nuclei, follow the general shape of the p-nucleus excitation functions quite well except for a general overestimation of the backward emission. For heavy ion reactions the calculated yield also falls off faster with decreasing beam energy than the data. No statistically significant narrow resonances are observed. {copyright} {ital 1997} {ital The American Physical Society}

  2. Cohering power of quantum operations

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Kaifeng, E-mail: bkf@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China); Kumar, Asutosh, E-mail: asukumar@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Zhang, Lin, E-mail: linyz@zju.edu.cn [Institute of Mathematics, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Junde, E-mail: wjd@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China)

    2017-05-18

    Highlights: • Quantum coherence. • Cohering power: production of quantum coherence by quantum operations. • Study of cohering power and generalized cohering power, and their comparison for differentmeasures of quantum coherence. • Operational interpretation of cohering power. • Bound on cohering power of a generic quantum operation. - Abstract: Quantum coherence and entanglement, which play a crucial role in quantum information processing tasks, are usually fragile under decoherence. Therefore, the production of quantum coherence by quantum operations is important to preserve quantum correlations including entanglement. In this paper, we study cohering power–the ability of quantum operations to produce coherence. First, we provide an operational interpretation of cohering power. Then, we decompose a generic quantum operation into three basic operations, namely, unitary, appending and dismissal operations, and show that the cohering power of any quantum operation is upper bounded by the corresponding unitary operation. Furthermore, we compare cohering power and generalized cohering power of quantum operations for different measures of coherence.

  3. Spin-relaxation without coherence loss: Fine-structure splitting of localized excitons

    DEFF Research Database (Denmark)

    Langbein, Wolfgang; Zimmermann, R.; Runge, E.

    2000-01-01

    We investigate the polarization dynamics of the secondary emission from a disordered quantum well after resonant excitation. Using the speckle analysis technique we determine the coherence degree of the emission, and find that the polarization-relaxed emission has a coherence degree comparable to...

  4. Partially coherent imaging and spatial coherence wavelets

    International Nuclear Information System (INIS)

    Castaneda, Roman

    2003-03-01

    A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function. (author)

  5. A model for pion-pion scattering in large-N QCD

    Energy Technology Data Exchange (ETDEWEB)

    Veneziano, G. [Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); Collège de France,11 place M. Berthelot, 75005 Paris (France); Yankielowicz, S. [Raymond and Beverly Sackler School of Physics Tel-Aviv University,Ramat-Aviv 69978 (Israel); Onofri, E. [I.N.F.N., Gruppo Collegato di Parma, c/o Department of Mathematical,Physical and Computer Sciences, Università di Parma,Parco Area delle Scienze 7/a, Parma, 43124 (Italy)

    2017-04-26

    Following up on recent work by Caron-Huot et al. we consider a generalization of the old Lovelace-Shapiro model as a toy model for ππ scattering satisfying (most of) the properties expected to hold in (’t Hooft’s) large-N limit of massless QCD. In particular, the model has asymptotically linear and parallel Regge trajectories at positive t, a positive leading Regge intercept α{sub 0}<1, and an effective bending of the trajectories in the negative-t region producing a fixed branch point at J=0 for tpion processes, a program we do not undertake in this paper.

  6. On Longitudinal Spectral Coherence

    DEFF Research Database (Denmark)

    Kristensen, Leif

    1979-01-01

    It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...... observation sites and the turbulence intensity influence the results. The limitations of the theory are discussed....

  7. Coherence Phenomena in Coupled Optical Resonators

    Science.gov (United States)

    Smith, D. D.; Chang, H.

    2004-01-01

    We predict a variety of photonic coherence phenomena in passive and active coupled ring resonators. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived, and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. We also demonstrate that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation, and use this result for the analysis of coupled-resonator photon dynamics. Notably, because these effects are predicted directly from coupled-mode theory, they are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators.

  8. Coherent Startup of an Infrared Free-Electron Laser

    NARCIS (Netherlands)

    Jaroszynski, D. A.; Bakker, R. J.; van der Meer, A. F. G.; Oepts, D.; van Amersfoort, P. W.

    1993-01-01

    Coherent enhancement of the spontaneous undulator radiation by several orders of magnitude has been observed in a free-electron laser at wavelengths from 40 to 100 mum. The coherent emission can be explained by details of the electron-beam micropulse structure. Furthermore, it has been found that

  9. Coherence Inherent in an Incoherent Synchrotron Radio Source ...

    Indian Academy of Sciences (India)

    It is well known that synchrotron radiation mechanism does not allow MASER type coherent emission (Pacholczyk 1970). Here we show that coherence can naturally occur in a synchrotron ... cally thick region (Fig. 1), then divides the synchrotron spectrum into an incoherent. 1A thin flat circular unleavened Indian bread.

  10. Coherent x-rays from PEP

    International Nuclear Information System (INIS)

    Baird, S.; Nuhn, H.-D.; Tatchyn, R.; Winick, H.; Fisher, A.S.; Gallardo, J.C.; Pellegrini, C.

    1991-01-01

    This paper explores the use of a large-circumference, high-energy, electron-positron collider such as PEP to drive a free-electron laser (FEL), producing high levels of coherent power at short wavelengths. The author consider Self-Amplified Spontaneous Emission (SASE), in which electron bunches with low emittance, high peak current and small energy spread radiate coherently in a single passthrough a long undulator. As the electron beam passes down the undulator, its interaction with the increasingly intense spontaneous radiation causes a bunch density modulation at the optical wavelength, resulting in stimulated emissional growth of coherent power in a single pass. The need for optical-cavity mirrors, which place a lower limit on the wavelength of a conventional FEL oscillator, is avoided. The authors explore various combinations of electron-beam and undulator parameters, as well as special undulator designs and optical klystrons (OK), to reach high average or peak coherent power at wavelengths around 40 angstrom by achieving significant exponential gain or full saturation. Examples are presented for devices that achieve high peak coherent power (up to about 400 MW) with lower average coherent power (about 20 mW) and other devices which produce a few watts of average coherent power

  11. Practical applications of coherent transition radiation

    International Nuclear Information System (INIS)

    Moran, M.J.

    1987-01-01

    The predictable nature of transition radiation (TR) emissions has been demonstrated under a wide variety of experimental conditions. The reliable character of TR allows the design of specific practical applications that use emissions from the optical to the x-ray spectral regions. Applications often can be enhanced by the spatial coherence of TR, and some have become highly developed. New applications may be developed through the use of other related radiation mechanisms. 20 refs., 3 figs

  12. Pion form factor in QCD at intermediate momentum transfers

    Science.gov (United States)

    Braun, V. M.; Khodjamirian, A.; Maul, M.

    2000-04-01

    We present a quantitative analysis of the electromagnetic pion form factor in the light-cone sum rule approach, including radiative corrections and higher-twist effects. The comparison to the existing data favors the asymptotic profile of the pion distribution amplitude and allows us to estimate the deviation: [∫du/uφπ(u)]/[∫du/uφasπ(u)]=1.1+/-0.1 at the scale of 1 GeV. Special attention is paid to the precise definition and interplay of soft and hard contributions at intermediate momentum transfer, and to the matching of the sum rule to the perturbative QCD prediction. We observe a strong numerical cancellation between the soft (end-point) contribution and power-suppressed hard contributions of higher twist, so that the total nonperturbative correction to the usual PQCD result turns out to be of the order of 30% for Q2~1 GeV2.

  13. Single- and double-charge exchange at low pion energies

    International Nuclear Information System (INIS)

    Baer, H.W.

    1991-01-01

    A review is given of pion single- and double-charge exchange reactions at incident energies of 25 to 65 MeV leading to isobaric analog states, and in the case of double-charge exchange leading to the ground state of the residual nucleus. The crucial role of the higher nuclear transparency at low pion energies for the analysis of the data in terms of single and double scattering is demonstrated. The large effects on double-charge exchange produced by the spatial correlations in nuclear wave functions are evident. The data on 1f 7/2 nuclei at 35 MeV are used to establish the general validity of a shell-model-based two-amplitude model for these transitions. Recent measurements of the energy dependence between 25 and 65 MeV of double-charge exchange cross sections at forward angles are presented and discussed. 33 refs., 19 figs

  14. Dispersive analysis of the pion transition form factor

    Science.gov (United States)

    Hoferichter, M.; Kubis, B.; Leupold, S.; Niecknig, F.; Schneider, S. P.

    2014-11-01

    We analyze the pion transition form factor using dispersion theory. We calculate the singly-virtual form factor in the time-like region based on data for the cross section, generalizing previous studies on decays and scattering, and verify our result by comparing to data. We perform the analytic continuation to the space-like region, predicting the poorly-constrained space-like transition form factor below , and extract the slope of the form factor at vanishing momentum transfer . We derive the dispersive formalism necessary for the extension of these results to the doubly-virtual case, as required for the pion-pole contribution to hadronic light-by-light scattering in the anomalous magnetic moment of the muon.

  15. High resolution studies of pion-nucleus reaction mechanism

    International Nuclear Information System (INIS)

    Morris, C.L.

    1983-01-01

    Pion inelastic scattering is generally well described as a first order process using the DWIA. This is especially true for a large body of inelastic scattering data to low-lying collective states which is well-described by form factors obtained in (e,e') and the DWIA. Some data for which this model does not work are presented. Higher order reaction mechanisms have been invoked to explain some of these data. However, no model of these second order processes gives a satisfactory explanation of the entire data set. Experimentally, more data for pion-induced transitions to low-spin unnatural-parity states which have been studied by other probes would be useful in sorting out the reaction mechanisms responsible for the anomalous cross sections observed for the 1 + states in 12 C. Theoretically, a consistent evaluation of possible second-order diagrams in inelastic scattering, such as is being attempted for DCX 22 , would be useful

  16. Diffractive dissociation into 3 pion final states at COMPASS

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Suh-Urk [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany); Brookhaven National Laboratory, Upton, NY 11973 (United States); Friedrich, Jan; Grabmueller, Stefanie; Haas, Florian; Ketzer, Bernhard; Neubert, Sebastian; Paul, Stephan; Weitzel, Quirin [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany); Ryabchikov, Dimitry [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany); Institute for High Energy Physics, 142284 Protvino (Russian Federation)

    2009-07-01

    Diffractive dissociation reactions at the COMPASS experiment, CERN, provide access to the meson resonance spectrum. During a pilot run in 2004, using a pion beam on a lead target, a competitive number of {pi}{sup -} {pi}{sup -} {pi}{sup +} final state events with masses below 2.5 GeV/c{sup 2} were recorded. After COMPASS had finished its muon program in 2007, it used in 2008 again a pion beam, but now a liquid hydrogen target, and gathered during several weeks a unique high statistics. A full partial wave analysis of the 2004 data has been performed, with the focus on the kinematic range of a large momentum transfer (0.1 GeV{sup 2}/c{sup 2} {<=} t' {<=} 1.0 GeV{sup 2}/c{sup 2}). In addition first results of the adjacent analysis with 2008 data are presented.

  17. Critical behavior and dimension crossover of pion superfluidity

    Science.gov (United States)

    Wang, Ziyue; Zhuang, Pengfei

    2016-09-01

    We investigate the critical behavior of pion superfluidity in the framework of the functional renormalization group (FRG). By solving the flow equations in the SU(2) linear sigma model at finite temperature and isospin density, and making comparison with the fixed point analysis of a general O (N ) system with continuous dimension, we find that the pion superfluidity is a second order phase transition subject to an O (2 ) universality class with a dimension crossover from dc=4 to dc=3 . This phenomenon provides a concrete example of dimension reduction in thermal field theory. The large-N expansion gives a temperature independent critical exponent β and agrees with the FRG result only at zero temperature.

  18. Goldstone pion and other mesons using a scalar confining interaction

    International Nuclear Information System (INIS)

    Gross, F.; Milana, J.

    1994-01-01

    A covariant wave equation for q bar q interactions with an interaction kernel composed of the sum of constant vector and linear scalar confining interactions is solved for states with two quarks with identical mass. The model includes an NJL-like mechanism which links the dynamical breaking of chiral symmetry to the spontaneous generation of quark mass and the appearance of a low mass Goldstone pion. A novel feature of this approach is that it automatically explains the small mass of the pion even though the linear potential is a scalar interaction in Dirac space, and hence breaks chiral symmetry. Solutions for mesons composed of light quarks (π,ρ, and low lying excited states) and heavy quarks (ρ c , J/Ψ, and low lying excited states) are presented and discussed

  19. Pion Electroproduction form Helium 3, Deuterium, and Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Avery, Stephen Milton [Hampton Univ., Hampton, VA (United States)

    2002-05-01

    A series of measurements for pion electroproduction from helium-3, deuterium, and hydrogen were completed at the Thomas Jefferson National Accelerator Facility by the NucPi Collaboration. E91003 began taking data in February 1998 and was completed in April 1998. The longitudinal and transverse parts of the differential cross section were extracted, by means of a Rosenbluth type separation, in the direction parallel to the virtual photon, at Q 2 = 0.4 GeV 2 , for W = 1.15 and W = 1.6 GeV. The mass dependence of the longitudinal cross section should provide insight into the surprising apparent absence of any significant cross section enhancement due to excess pions in the nuclear medium.

  20. Bethe-Salpeter analysis of the radiative pion disintegration

    Energy Technology Data Exchange (ETDEWEB)

    Abad, J.; Pacheco, A.F. (Zaragoza Univ. (Spain). Dept. de Fisica Teorica); Rodriguez-Trias, R.; Esteve, J.G. (Paris-11 Univ., 91 - Orsay (France). Lab. de Physique Theorique et Hautes Energies)

    1990-04-01

    The structure-dependent amplitude of the decay {pi}{yields}e{nu}{gamma} is evaluated in the framework of a Bethe-Salpeter description for the pion. We assume a general B-S wave function in the S-wave. Within this hypothesis, we show that the gauge invariance constrains the different contributions of the wave functions to the amplitude, resulting in the vanishing of the axial form factor. (orig.).