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Träfflista för sökning "WFRF:(Oelert W.) "

Sökning: WFRF:(Oelert W.)

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1.
  • Adolph, C, et al. (författare)
  • Measurement of the eta -> 3 pi(0) Dalitz plot distribution with the WASA detector at COSY
  • 2009
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 677:1-2, s. 24-29
  • Tidskriftsartikel (refereegranskat)abstract
    • In the first production run of the WASA experiment at COSY, the eta decay into three neutral pions was measured in proton-proton interactions at a proton beam kinetic energy of 1.4 GeV. The Dalitz plot of the three pious was Studied using 1.2 x 10(5) fully reconstructed events. and the quadratic slope parameter alpha was determined to be -0.027 +/- 0.008(stat) +/- 0.005(syst). The result is consistent with previous measurements and further corroborates the importance of pion-pion final state interactions. (C) 2009 Elsevier B.V. All rights reserved.
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2.
  • Bargholtz, Chr., et al. (författare)
  • The WASA detector facility at CELSIUS
  • 2008
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 594:3, s. 339-350
  • Tidskriftsartikel (refereegranskat)abstract
    • The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given. (C) 2008 Elsevier B.V. All rights reserved.
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3.
  • Barnes, PD, et al. (författare)
  • Antihyperon-hyperon production in the threshold region at LEAR
  • 1996
  • Ingår i: PHYSICS OF ATOMIC NUCLEI. - : AMER INST PHYSICS. ; , s. 1460-1466
  • Konferensbidrag (refereegranskat)abstract
    • The experiment PSI185 studies the antihyperon-hyperon production in antiproton-proton annihilation at LEAR/CERN up to 2 GeV/c. This is achieved by investigation of the channels (p) over bar p --> <(Lambda)over bar>Lambda, <(Lambda)over bar>Sigma(0) + c.c.
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4.
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5.
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6.
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7.
  • Clement, H., et al. (författare)
  • Search for narrow NN-decoupled resonances in the πNN-system : An overview
  • 1996
  • Ingår i: Progress in Particle and Nuclear Physics. - : Elsevier BV. - 0146-6410 .- 1873-2224. ; 36, s. 369-378
  • Tidskriftsartikel (refereegranskat)abstract
    • The status of the search for NN-decoupled resonances in the πNN-system is reviewed. After a short survey on the history of dibaryon searches reactions suitable for detecting such resonances are discussed. Special emphasis is put on the pionic double charge exchange, where recently evidence for the signature of a narrow πNN resonance, called d′, with I(J P) = even (0 -) and m = 2.06 GeV has been quoted. Further reactions discussed in this context are the pion photoproduction on the deuteron and the two-pion production in nucleon-nucleon collisions.
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8.
  • Czerwinski, E., et al. (författare)
  • Determination of the Total Width of the η′ Meson
  • 2010
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:12, s. 122001-
  • Tidskriftsartikel (refereegranskat)abstract
    • Taking advantage of both the low-emittance proton beam of the cooler synchrotron COSYand the high momentum precision of the COSY-11 detector system, the mass distribution of the eta' meson was measured with a resolution of 0: 33 MeV/c(2) (FWHM), improving the experimental mass resolution by almost an order of magnitude with respect to previous results. Based on the sample of more than 2300 reconstructed pp -> pp eta' events, the total width of the eta' meson was determined to be Gamma(eta') = 0.226 +/- 0: 017(stat) +/- 0: 014(syst) MeV/c(2).
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9.
  • Klaja, J., et al. (författare)
  • Upper limit of the total cross section for the pn -> pn eta ' reaction
  • 2010
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 81:3, s. 035209-
  • Tidskriftsartikel (refereegranskat)abstract
    • The upper limit of the total cross section for the pn -> pn eta' reaction has been determined near the kinematical threshold in the excess energy range from 0 to 24 MeV. The measurement was performed using the COSY-11 detector setup, a deuteron cluster target, and the proton beam of COSY with a momentum of 3.35 GeV/c. The energy dependence of the upper limit of the cross section was extracted exploiting the Fermi momenta of nucleons inside the deuteron. Comparison of the determined upper limit of the ratio R-eta' = sigma(pn -> pn eta')/sigma(pp -> pp eta') with the corresponding ratio for eta-meson production does not favor the dominance of the N*(1535) resonance in the production process of the eta' meson and suggests nonidentical production mechanisms for eta and eta' mesons.
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10.
  • Moskal, P., et al. (författare)
  • Invariant-mass distributions for the pp -> pp eta reaction at Q=10 MeV
  • 2010
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 43:2, s. 131-136
  • Tidskriftsartikel (refereegranskat)abstract
    • Proton-proton and proton-eta invariant-mass distributions and the total cross-section for the pp -> pp eta reaction have been determined near the threshold at an excess energy of Q = 10 MeV. The experiment has been conducted using the COSY-11 detector setup and the cooler synchrotron COSY. The determined invariant-mass spectra reveal significant enhancements in the region of low proton-proton relative momenta, similarly as observed previously at higher excess energies of Q = 15.5 MeV and Q = 40 MeV.
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11.
  • Paschke, K. D., et al. (författare)
  • Experimental determination of the complete spin structure for (p)over-barp ->(Lambda)over-bar Lambda at p((p)over-bar)=1.637 GeV/c
  • 2006
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 74:1, s. 015206-
  • Tidskriftsartikel (refereegranskat)abstract
    • The reaction (p) over barp -> (Lambda) over bar Lambda -> (p) over bar pi(+)p pi(-) has been measured with high statistics at a beam momentum of p((p) over bar)=1.637GeV/c. The use of a transversely polarized frozen-spin target combined with the self-analyzing property of Lambda/(Lambda) over bar decay allows access to unprecedented information on the spin structure of the interaction. The most general spin-scattering matrix can be written in terms of 11 real parameters for each bin of scattering angle; each of these parameters is determined with reasonable precision. From these results, all conceivable spin correlations are determined with inherent self-consistency. Good agreement is found with the few previously existing measurements of spin observables in (p) over barp ->(Lambda) over bar Lambda near this energy. Existing theoretical models do not give good predictions for those spin observables that had not been previously measured.
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12.
  • Przerwa, J., et al. (författare)
  • ISOSPIN DEPENDENCE OF THE eta ' MESON PRODUCTION IN NUCLEON-NUCLEON COLLISIONS
  • 2009
  • Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 24:2-3, s. 458-461
  • Tidskriftsartikel (refereegranskat)abstract
    • A comparison of the close-to-threshold total cross section for the eta' production in pp -> pp eta' and pn -> pn eta' reactions constitutes a tool to investigate the eta' meson structure and the reaction mechanism in the channels of isospin I = 0 and I = 1 and may provide insight into the flavour-singlet (perhaps also into gluonium) content of the eta' meson. In this contribution we present preliminary results of measurement of the quasifree production of the eta' meson in the proton-neutron collisions conducted using the COSY-11 facility.
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13.
  • Alfs, D., et al. (författare)
  • Drift chamber calibration and particle identification in the P-349 experiment
  • 2019
  • Ingår i: MESON 2018 - 15th International Workshop on Meson Physics. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • The goal of the P-349 experiment is to test whether 3.5 GeV/c antiprotons produced in high-energy proton-proton collisions are polarized in view of the preparation of a polarized antiproton beam. In this article, we present the details of the ongoing analysis focused on the drift chambers calibration and particle identification with DIRC.
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14.
  • Alfs, D., et al. (författare)
  • Drift Chamber Calibration And Track Reconstruction In The P349 Antiproton Polarization Experiment
  • 2017
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 48:10, s. 1983-1988
  • Tidskriftsartikel (refereegranskat)abstract
    • The goal of the P349 experiment is to test whether the antiproton production process can be itself a source of antiproton polarization. In this article, we present the motivation and details of the performed measurement. We report on the status of the analysis focusing mainly on calibration of the drift chambers and 3d track reconstruction.
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15.
  • Alfs, D., et al. (författare)
  • Status of the analysis for the search of polarization in the antiproton production process
  • 2016
  • Ingår i: MESON 2016 - 14th International Workshop On Meson Production, Properties And Interaction. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • The P-349 experiment aims to test whether for antiprotons the production process itself can be a source of polarization in view of the preparation of a polarized antiproton beam. In this article we present the details of performed measurements and report on the status of the ongoing analysis.
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16.
  • Bargholtz, Chr., et al. (författare)
  • Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
  • 2007
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
  • Tidskriftsartikel (refereegranskat)abstract
    • The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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17.
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18.
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19.
  • Bashkanov, M., et al. (författare)
  • Exclusive measurements of pd -> He-3 pi pi : The ABC effect revisited
  • 2006
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 637:4-5, s. 223-228
  • Tidskriftsartikel (refereegranskat)abstract
    • Exclusive measurements of the reactions pd -> He-3 pi(+)7 pi(-) and pd -> He-3 pi(0)pi(0) have been carried out at T-p = 0.893 GeV at the CELSIUS storage ring using the WASA detector. The pi(+)pi(-) channel evidences a pronounced enhancement at low invariant pi pi masses-as anticipated from previous inclusive measurements of the ABC effect. This enhancement is seen to be even much larger in the isoscalar pi(0)pi(0) channel. The differential distributions prove this enhancement to be of scalar-isoscalar nature. Delta Delta calculations give a good description of the data, if a boundstate condition is imposed for the intermediate Delta Delta system.
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20.
  • Bashkanov, M., et al. (författare)
  • Measurement of the slope parameter for the η → 3π0 decay in the pp → ppη reaction
  • 2007
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 048201-
  • Tidskriftsartikel (refereegranskat)abstract
    • The CELSIUS-WASA setup is used to measure the 3π0 decay of η mesons produced in pp interactions with beam kinetic energies of 1.36 and 1.45 GeV. The efficiency-corrected Dalitz plot and density distributions for this decay are shown, together with a fit of the quadratic slope parameter α yielding α = −0.026 ± 0.010(stat) ± 0.010(syst). This value is compared to recent experimental results and theoretical predictions.
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21.
  • Berlowski, M., et al. (författare)
  • Measurement of eta meson decays into lepton-antilepton pairs
  • 2008
  • Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 77:3, s. 032004-
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta -> e(+)e(-)e(+)e(-) events are reported with a background of 1.3 +/- 0.2 events. This allows to set an upper limit to the branching ratio of 9.7x10(-5) (90% CL). The branching ratio for the decay eta -> e(+)e(-)gamma is determined to (7.8 +/- 0.5(stat)+/- 0.8(syst))x10(-3) in agreement with world average value. An upper limit (90% CL) for the branching ratio for the eta -> e(+)e(-) decay is 2.7x10(-5) and a limit for the sum of the eta ->mu(+)mu(-)mu(+)mu(-) and eta ->pi(+)pi(-)mu(+)mu(-) decays is 3.6x10(-4).
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22.
  • Bilger, R, et al. (författare)
  • 2 pi production in pp collisions close to threshold
  • 2000
  • Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. ; , s. 469C-472C
  • Konferensbidrag (refereegranskat)abstract
    • The reaction pp --> NN pi pi has been measured close to threshold in the energy range from 650 to 775 MeV using the PROMICE/WASA setup at CELSIUS. These data constitute the first exclusive high-statistics measurements of this reaction on a pure hydrogen t
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23.
  • Bilger, R, et al. (författare)
  • Cross sections of the pp -> pp pi(0) reaction between 310 and 425 MeV
  • 2001
  • Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 693:3-4, s. 633-662
  • Tidskriftsartikel (refereegranskat)abstract
    • Extensive kinematically complete measurements of the pp --> pp pi (0) reaction have been made at six beam energies: 310, 320, 340, 360, 400, and 425 MeV. Angles and energies of both final-state protons are extracted from the forward detector system of the
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24.
  • Bilger, R, et al. (författare)
  • Recent measurements of the eta production in pd collisions at CELSIUS
  • 1996
  • Ingår i: ACTA PHYSICA POLONICA B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. ; , s. 2985-2991
  • Konferensbidrag (refereegranskat)abstract
    • The reactions pd --> eta + X have been measured at four beam energies: 930, 965, 1037 and 1100 MeV. The reactions were identified by detecting charged particles in plastic scintillator detectors and the eta photons in two arrays of CsI(Na) crystals. A pre
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25.
  • Bilger, R, et al. (författare)
  • Search for a narrow pi NN-resonance in pp->pp pi(+)pi(-)
  • 1996
  • Ingår i: PROGRESS IN PARTICLE AND NUCLEAR PHYSICS. - : PERGAMON PRESS LTD. ; , s. 379-381
  • Konferensbidrag (refereegranskat)abstract
    • We report on the current status of the search for the pi NN-resonance d' with I(J(P)) = 0(0(-)) and M = 2.06 GeV in the 2 pi production in pp collisions.
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26.
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27.
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28.
  • Brodowski, W, et al. (författare)
  • A signal of a narrow pi NN resonance in pp->pp pi(-)pi(+)
  • 1996
  • Ingår i: ZEITSCHRIFT FUR PHYSIK A-HADRONS AND NUCLEI. - : SPRINGER VERLAG. - 0939-7922. ; 355:1, s. 5-8
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on the first exclusive measurement of the 2 pi production in NN collisions at T-p = 750 MeV using a H-2 cluster jet target and the WASA/PROMICE detector at CELSIUS. In the invariant-mass spectrum M(pp pi-) we observe a narrow peak at 2.063(2) Ge
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29.
  • Brodowski, W, et al. (författare)
  • Exclusive measurement of pp -> pp pi(+)pi(-) at CELSIUS
  • 2000
  • Ingår i: ACTA PHYSICA POLONICA B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254. ; 31:10-11, s. 2295-2298
  • Tidskriftsartikel (refereegranskat)abstract
    • With the PROMICE/WASA detector setup at CELSIUS the reaction pp --> NN pi pi has been measured in the energy range from 650 to 775 MeV. These data constitute the first exclusive high-statistics measurements on a pure hydrogen target, supplying both differ
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30.
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31.
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32.
  • Calén, H., et al. (författare)
  • Detector setup for a storage ring with an internal target
  • 1996
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 379:1, s. 57-75
  • Tidskriftsartikel (refereegranskat)abstract
    • A detector setup for the cooler storage ring CELSIUS is described. The setup detects particles produced in interactions between the internal beam and a cluster-jet target. Particles emitted in the forward direction are measured by means of arrays of plastic scintillators and proportional counters. Particles, particularly photons, emitted more isotropically are measured by means of two calorimeters containing CsI(Na) crystals. The performance of the setup is given for neutral meson production in proton-proton and proton-deuteron interactions in the energy range 290-1360 MeV.
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33.
  • Calén, H, et al. (författare)
  • Measurement of the quasifree pn -> pn eta reaction
  • 1998
  • Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMERICAN PHYSICAL SOC. - 0556-2813. ; 58:5, s. 2667-2670
  • Tidskriftsartikel (refereegranskat)abstract
    • The first measurement of the cross section of the quasifree pn-->pn eta reaction has been carried out at the CELSIUS storage ring using a deuterium internal cluster jet target. The energy dependence of the cross section is extracted using a fixed incident
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34.
  • Calén, H, et al. (författare)
  • Upper limits for a narrow dibaryon in pp collisions at 200 and 310 MeV
  • 1998
  • Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 427:3-4, s. 248-253
  • Tidskriftsartikel (refereegranskat)abstract
    • Dibaryons, forbidden by mass to decay into NN pi channel and by quantum numbers into NN channel, may still have escaped detection. In fact, recently an observation of a narrow dibaryon (D) with the mass close to 1920 MeV was reported in the process pp -->
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35.
  • Czerwinski, E., et al. (författare)
  • Determination of the eta '-Proton Scattering Length in Free Space
  • 2014
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 113:6, s. 062004-
  • Tidskriftsartikel (refereegranskat)abstract
    • Taking advantage of both the high mass resolution of the COSY-11 detector and the high energy resolution of the low-emittance proton beam of the cooler synchrotron COSY, we determine the excitation function for the pp --> pp eta' reaction close to threshold. Combining these data with previous results, we extract the scattering length for the eta'-proton potential in free space to be Re(alpha(p eta)') = 0 +/- 0.43 fm and Im(alpha(p eta)') = 0.37(-0.16)(+0.40) fm.
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36.
  • Grzonka, D., et al. (författare)
  • Polarization analysis of <(p)over bar> produced in pA collisions
  • 2019
  • Ingår i: MESON 2018 - 15th International Workshop on Meson Physics. - : EDP Sciences.
  • Konferensbidrag (refereegranskat)abstract
    • A quite simple procedure for the generation of a polarized antiproton beam could be worked out if antiprotons are produced with some polarization. In order to investigate this possibility measurements of the polarization of produced antiprotons have been started at a CERN/PS test beam. The polarization will be determined from the asymmetry of the elastic antiproton scattering at a liquid hydrogen target in the CNI region for which the analyzing power is well known. The data are under analysis and an additional measurement is done in 2018. Details on the experiment and the ongoing data analysis will be given.
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37.
  • Grzonka, D., et al. (författare)
  • Search for Polarization Effects in the Antiproton Production Process
  • 2015
  • Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 46:1, s. 191-201
  • Tidskriftsartikel (refereegranskat)abstract
    • For the production of a polarized antiproton beam, various methods have been suggested including the possibility that antiprotons may be produced polarized which will be checked experimentally. The polarization of antiprotons produced under typical conditions for antiproton beam preparation will be measured at the CERN/PS. If the production process creates some polarization, a polarized antiproton beam could be prepared by a rather simple modification of the antiproton beam facility. The detection setup and the expected experimental conditions are described.
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38.
  • Grzonka, D., et al. (författare)
  • Search for polarized antiproton production
  • 2019
  • Ingår i: Hyperfine Interactions. - : Springer Nature. - 0304-3843 .- 1572-9540. ; 240
  • Tidskriftsartikel (refereegranskat)abstract
    • The production of antiprotons is studied in view of possible polarization effects as basis for a polarized antiproton beam. If antiprotons are produced with some polarization, a quite simple procedure for the generation of a polarized antiproton beam could be worked out. The experiments are performed at the CERN PS test beam T11 where secondary particles with momenta around 3.5 GeV/c are selected. The polarization analysis is performed by measuring the asymmetry of the elastic (p) over barp-scattering in the Coulomb-nuclear interference region. The detection system includes Cherenkov and tracking detectors for the particle identification and the 3d track reconstruction. Details on the detection system and the status of the analysis are given.
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39.
  • Keleta, S, et al. (författare)
  • Exclusive measurement of two-pion production in the dd -> He-4 pi pi reaction
  • 2009
  • Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 825:1-2, s. 71-90
  • Tidskriftsartikel (refereegranskat)abstract
    • The results from the first kinematically complete measurement of the dd -> He-4 pi pi reaction are reported. The aim was to investigate a long standing puzzle regarding the origin of the peculiar pi pi-invariant mass distributions appearing in double pion production in light ion collisions, the so-called ABC effect. The measurements were performed at the incident deuteron energies of 712 MeV and 1029 MeV. with the WASA detector assembly at CELSIUS in Uppsala, Sweden. We report the observation of a characteristic enhancement at low pi pi-invariant mass at 712 MeV, the lowest energy yet. At the higher energy, in addition to confirming previous experimental observations, Our results reveal a strong angular dependence of the pions in the overall centre of mass system. The results are qualitatively reproduced by a theoretical model, according to which the ABC effect is described as resulting from a kinematical enhancement in the production of the pion pairs from two parallel and independent NN -> d pi sub-processes. (C) 2009 Elsevier B.V. All rights reserved.
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40.
  • Moskal, P., et al. (författare)
  • Near-threshold production of the eta meson via the quasifree pn -> pn eta reaction
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:1, s. 015208-
  • Tidskriftsartikel (refereegranskat)abstract
    • Total cross sections for the quasifree pn -> pn eta reaction in the range from the kinematical threshold up to 20 MeV excess energy have been determined. At threshold they exceed corresponding cross sections for the pn -> pn eta reaction by a factor of about 3 in contrast to the factor of 6 established for higher excess energies. To large extent, the observed decrease of the ratio s(pn -> pn eta)/s=sigma(pn -> pn eta) toward threshold may be assigned to the different energy dependence of the proton-proton and proton-neutron final-state interactions. The experiment was conducted using a proton beam of the cooler synchrotron COSY and a cluster jet deuteron target. The proton- neutron reactions were tagged by the spectator proton whose momentum was measured for each event. Protons and neutron outgoing from the pn -> pn eta reaction have been registered by means of the COSY-11 facility, an apparatus dedicated for threshold meson production.
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41.
  • Pauly, C., et al. (författare)
  • The pp→ppπππ reaction channels in the threshold region
  • 2007
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 649:2-3, s. 122-127
  • Tidskriftsartikel (refereegranskat)abstract
    • The cross section for direct neutral and charged three pion production in pp interactions was measured at excess energies in the range 160–216 MeV. That comprises the first measurement of the pp→ppπ0π0π0 reaction and the direct comparison with the pp→ppπ+π−π0 process. The experiment was performed above the η meson production threshold and the cross section could be directly normalized to the cross section of the pp→ppη reaction, with the η decaying into 3 pions. Since the same final states are selected, the measurement has a low systematical error. The measured cross section ratio σ(pp→ppπ+π−π0)/σ(pp→ppπ0π0π0) is compared to predictions of dominance of different isobars in the intermediate state.
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42.
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43.
  • Schonning, K., et al. (författare)
  • The pd -> He-3 eta pi(0) reaction at T-p=1450 MeV CELSIUS/WASA Collaboration
  • 2010
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 685:1, s. 33-37
  • Tidskriftsartikel (refereegranskat)abstract
    • The cross section for the pd -> He-3 eta pi(0) reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring. The He-3 was detected in coincidence with four photons from the decays of the two mesons. The data indicate that the production mechanism involves the formation of the Delta(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant mass distributions Of all three pairs of final particles are well reproduced by a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the pi(0) momentum in the He-3 pi(0) system.
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44.
  • Schönning, Karin, et al. (författare)
  • Polarisation of the omega meson in the pd -> He-3 omega reaction at 1360 and 1450 MeV
  • 2008
  • Ingår i: Physics Letters B. - elsevier : Elsevier BV. - 0370-2693 .- 1873-2445. ; 668:4, s. 258-262
  • Tidskriftsartikel (refereegranskat)abstract
    • The tensor polarisation of omega mesons produced in the pd -> He-3 omega reaction has been studied at two energies near threshold. The 3 He nuclei were detected in coincidence with the pi(0)pi(+)pi(-) or pi(0)gamma decay products of the omega. in contrast to the case of phi-meson production, the omega mesons are found to be unpolarised. This brings into question the applicability of the Okubo-Zweig-lizuka rule when comparing the production of vector mesons in low energy hadronic reactions.
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45.
  • Schönning, Karin, et al. (författare)
  • Production of eta and 3 pi mesons in the pd -> (HeX)-He-3 reaction at 1360 and 1450 MeV
  • 2010
  • Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 45:1, s. 11-21
  • Tidskriftsartikel (refereegranskat)abstract
    • The cross-sections of the pd -> He-3 eta, pd -> He-3 pi(0)pi(0)pi(0) and pd -> He-3 pi(+)pi(-)pi(0) reactions have been measured at the beam kinetic energies T-p = 1360 MeV and T-p = 1450 MeV using the CELSIUS/WASA detector setup. At both energies, the differential cross-section d sigma/d Omega of the eta meson in the pd -> He-3 eta reaction shows a strong forward-backward asymmetry in the CMS. The ratio between the pd -> He-3 pi(+)pi(-)pi(0) and pd -> He-3 pi(0)pi(0)pi(0) cross-sections has been analysed in terms of isospin amplitudes. The reconstructed invariant-mass distributions of the pi pi, He-3 pi and (3)He2 pi systems provide hints on the role of nucleon resonances in the 3 pi production process.
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46.
  • Schönning, Karin, et al. (författare)
  • Production of the omega meson in the pd -> He-3 omega reaction at 1450 MeV and 1360 MeV
  • 2009
  • Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:4, s. 044002-
  • Tidskriftsartikel (refereegranskat)abstract
    • The production of omega mesons in the pd -> He-3 omega reaction has been studied at two energies near the kinematic threshold, T-p = 1450 MeV and T-p = 1360 MeV. The differential cross section was measured as a function of the omega c.m. angle at both energies over the whole angular range. Whereas the results at 1360 MeV are consistent with isotropy, strong rises are observed near both the forward and backward directions at 1450 MeV. Calculations made using a two-step model with an intermediate pion fail to reproduce the shapes of the measured angular distributions and also underestimate the total cross sections.
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47.
  • Schönning, Karin, et al. (författare)
  • The pd →3Heηπ0 reaction at Tp = 1450 MeV
  • 2010
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 685:1, s. 33-37
  • Tidskriftsartikel (refereegranskat)abstract
    • The cross section for the pd→3Heηπ0 reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring and detecting one 3He and four photons from the decays of the two mesons. The data indicate that the production mechanism involves the formation of the Δ(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant masses of all three pairs of final particles are well reproduce dby a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the π0 momentum in the 3He π0 system.
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48.
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  • Differential cross sections of the pp -> pp pi(0) reaction from 310 to 425 MeV
  • 2000
  • Ingår i: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 663, s. 452C-456C
  • Tidskriftsartikel (refereegranskat)abstract
    • Measurements of the differential cross sections of the pp --> pp pi(0) reaction at 310, 320, 340, 360, 400 and 425 MeV have been carried out at the CELSIUS storage ring in Uppsala. An attempt has been made to describe the distributions obtained in terms o
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49.
  • Akimov, D., et al. (författare)
  • Physics with WASA and PROMICE
  • 1994
  • Ingår i: Physics with GeV-particle beams, Juelich 1994. ; , s. 519-530
  • Konferensbidrag (refereegranskat)
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50.
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