D. F. Ottewell

Publications (8)0 Total impact

• Source

  Available from: Marcello M. Pavan

  Article: Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance

  M. M. Pavan, J. T. Brack, F. Duncan, A. FELTHAM, G Jones, J. Lange, K. J. Raywood, M. E. Sevior, R. Adams, D. F. Ottewell, G R Smith, B. Wells, R. L. Helmer, E. L. Mathie, R. Tacik, R.A. Ristinen, I. I. Strakovsky, H. M. Staudenmaier
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  ABSTRACT: A precision measurement of absolute pi+p and pi-p elastic differential cross sections at incident pion laboratory kinetic energies from T_pi= 141.15 to 267.3 MeV is described. Data were obtained detecting the scattered pion and recoil proton in coincidence at 12 laboratory pion angles from 55 to 155 degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm measurements were also obtained for pi+p energies up to 218.1 MeV, with the scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled, super-cooled liquid hydrogen target as well as solid CH2 targets were used. The data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5% normalization. The reliability of the cross section results was ensured by carrying out the measurements under a variety of experimental conditions to identify and quantify the sources of instrumental uncertainty. Our lowest and highest energy data are consistent with overlapping results from TRIUMF and LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA solution KH80 does not. Comment: 39 pages, 22 figures (some with quality reduced to satisfy ArXiv requirements. Contact M.M. Pavan for originals). Submitted to Physical Review C
  03/2001;
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  Available from: arxiv.org

  Article: Study of Two-Step Mechanisms in Pion Absorption on 6Li, 12C via Deuteron Emission

  G. M. Huber, G. J. Lolos, Z. Papandreou, J. Hovdebo, S. I. H. Naqvi, D. F. Ottewell, P. L. Walden, G Jones, X. Aslanoglou
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  ABSTRACT: The (pi+,pd), and (pi+,dd) reactions were investigated with pions of 100 and 165 MeV kinetic energy on 6Li and 12C targets. In comparison with previously published (pi+,pp) data on the same targets and at the same beam energies, kinematic regions were identified in which the neutron pickup process n+p->d dominated the observed deuteron yield. The importance of this mechanism increases with energy, contributing half of the observed cross section at 165 MeV. The contribution of direct quasi-triton absorption is significant only at 100 MeV. Comment: 23 pages, 12 figures
  09/2000;
• Article: Experimental study of the near threshold π^{+} p→ π^{+} π^{+} n cross section and chiral symmetry

  M. E. Sevior, A. Ambardar, J. T. Brack, P. Camerini, F. Duncan, J. Ernst, A. Feltham, N. Grion, R. R. Johnson, G. Koch, O. Meirav, D. F. Ottewell, R. Rui, G. R. Smith, V. Sossi, D. Theis, D. Vetterli
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  ABSTRACT: Total cross-section measurements of the π+p→π+π+n reaction at pion kinetic energies of 180, 184, 190, and 200 MeV are reported. The threshold value for the amplitude a(π+π+) as well as the s-wave, isospin 2, ππ scattering length a20 were determined. The results were found to be in agreement with chiral perturbation theory and inconsistent with the calculations of Jacob and Scadron and the model of dominance by quark loop anomalies.
  Phys. Rev. D. 10/1993; 48(9).
• Article: Multinucleon contributions to the 12C(π+, pp) reaction at 100 and 165 MeV incident pion energies

  G.M. Huber, G.J. Lolos, Z. Papandreou, J.C. Cormier, E.L. Mathie, S.I.H. Naqvi, D.F. Ottewell, P.L. Walden, G. Jones, R.P. Trelle, X. Aslanoglou, J.L. Visschers
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  ABSTRACT: Differential and total cross sections for π+ absorption on 12C are presented at incident pion energies of 100 and 165 MeV. This is the first time that this reaction has been measured with a combination of good energy and angle information over an extensive region of phase space. Results are compared to extensive Monte Carlo simulations in order to investigate the role of two- and multinucleon absorption processes in this nucleus. Signatures of ISI and FSI in the pion absorption process are also investigated, in order to explain the complex reaction mechanism implied by the data.
  Nuclear Physics A.
• Source

  Available from: Pierre-André Amaudruz

  Article: The CHAOS Spectrometer for Pion Physics at TRIUMF

  G R Smith, P.-A. Amaudruz, J. T. Brack, L. Felawka, A V Gorelov, R A Henderson, D. F. Ottewell, P Vincent, Y Wu, F. Bonutti, [......], S McFarland, K. Raywood, M. E. Sevior, E. L. Mathie, R. Tacik, P Reeve, R.A. Ristinen, E. F. Gibson, R. Meier, H. M. Staudenmaier
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  ABSTRACT: 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 Cherenkov 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° in the horizontal plane, and ±7° 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).
• Source

  Available from: Gary Dale Wait

  Article: POLARIZATION MEASUREMENTS IN PION DEUTERON BREAKUP AND ABSORPTION

  E. L. Mathie, D.M. Yeomans, G. M. Huber, G. J. Lolos, S. I. H. Naqvi, V. PAFILIS, Z. Papandreou, A. FELTHAM, R. OLSZEWSKI, G Jones, [......], M. SEVIOR, R.P. TRELLE, P Weber, D. GILL, D. HEALEY, D. F. Ottewell, G R Smith, G. WAIT, P. WALDEN, R. Rui
  http://dx.doi.org/10.1051/jphyscol:1990634.
• Source

  Available from: Gary Dale Wait

  Article: ANALYZING POWER MEASUREMENTS IN πd ELASTIC SCATTERING AT 50 MeV

  N.R. STEVENSON, R.B. SCHUBANK, Y.M. SHIN, P. Amaudruz, P.P.J. Delheij, D C Healey, B.K. JENNINGS, D. F. Ottewell, G. Sheffer, G R Smith, [......], D Vetterli, P Weber, M. KOHLER, R.A. Ristinen, E. L. Mathie, R. Tacik, M. YEOMANS, C.A. GOSSETT, G. J. Wagner, B.E. KING
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  ABSTRACT: Nos mesures du pouvoir d'analyse vectoriel dans la diffusion élastique πd à 50 MeV sont en accord avec les prédictions des modèles qui incluent la partie P11 du potentiel πN intégral mais sont en désaccord avec ceux qui omettent ou suppriment cette composante. Measurements of the vector analyzing power in πd elastic scattering at 50 MeV are found to agree well with model calculations that include the full πN P11 potential and disagree when this is omitted or suppressed.
  http://dx.doi.org/10.1051/jphyscol:1990636.
• Article: Measurement of t_ {20} in π^{+} d elastic scattering

  N. R. Stevenson, Y. M. Shin, K. Itoh, G. Retzlaff, D. R. Gill, D. F. Ottewell, G. D. Wait, T. E. Drake, D. Frekers, R. B. Schubank, G. J. Lolos
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  ABSTRACT: Measurements of the tensor polarization t20 in π+d elastic scattering have been performed at θdlab=15° between Tπ=116 and 145 MeV. Angular distributions at 133 and 140 MeV were also determined. These results resolve the discrepancy that has existed between the measurements made by other groups at SIN and at LAMPF, as our values are negative for all energies and angles investigated and consistent with the LAMPF data. Our results are also in good agreement with the corresponding measurements of analyzing powers. Lack of any significant oscillatory nature is in general agreement with theories at these kinematic regions and does not lend support to exotic effects such as dibaryon resonances.
  Phys. Rev. C. 39(4).