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Item Metadata only Distorted wave theory of the 50 MeV (p, 2p) reaction(Elsevier, 1969) McCarthy, I.E.; Thomas, A.W.An attempt is made to answer the question whether distorting potentials that give really good fits to elastic scattering cross sections and total reaction cross sections for experiments in the relevant two-body subsystems can correctly give positions of maxima and minima in the (p, 2p) angular correlation. The 50 MeV energy range is chosen because the angular correlation is very sensitive to the distortion. It is found that the positions are correctly reproduced by good elastic scattering parameters for the reaction 89Y(p, 2p)88Sr, Q = 7.44 MeV, at 46 MeV. The shortcoming of the distorted wave theory at this energy, as at higher energies, is that the calculated ratio of the cross section at small angles to that at large angles is too large. Apart from this serious defect, the shape of the angular correlation for 12C(p, 2p)11B, Q = 16 MeV, at 50 MeV is also encouraging. Previous studies suggest that the defect can be corrected if a better description of the p-p t-matrix is used in the distorted wave theory.Item Metadata only Importance of the D-state probability of the deuteron in threshold p + p → π + d(American Physical Society, 1971) Thomas, A.W.; Afnan, I.R.Abstract not availableItem Metadata only Pion absorption and the pion-deuteron scattering length(Elsevier, 1973) Thomas, A.W.; Afnan, I.R.The solution of the Faddeev equation for the πNN system has been used as a model for studying pion absorption and elastic scattering on the deuteron. Results indicate that absorption is sensitive to the short range behaviour of the deuteron wave function. The contribution of absorption to the πd scattering length is found to be small.Item Metadata only Faddeev approach to pion production and pion-deuteron scattering(American Physical Society, 1974) Afnan, I.R.; Thomas, A.W.Abstract not availableItem Metadata only Charge symmetry as a constraint on off-shell effects in the three-nucleon system(Elsevier, 1975) Thomas, A.W.; Afnan, I.R.Abstract not availableItem Metadata only A three-body calculation of πd scattering(North-Holland Pubhshtng Co., 1976) Thomas, A.W.Abstract not availableItem Metadata only A theory of low energy pion-nucleus scattering(North-Holland Publishing Co., 1978) Landau, R.H.; Thomas, A.W.Abstract not availableItem Metadata only The effect of genuine pion absorption and emission on πd scattering(Elsevier, 1979) Rinat, A.S.; Starkand, Y.; Hammel, E.; Thomas, A.W.Intermediate pion absorption and reemission through π and ϱ rescattering has been included in a computation of πd elastic cross sections and polarizations for pion energies through the resonance region. Appreciable effects are computed for these observables, notably for polarizations.Item Metadata only The case for studying the (π, πN) reaction in coincidence under optimum conditions(Elsevier B.V., 1979) Jackson, D.F.; Ioannides, A.A.; Thomas, A.W.Abstract not availableItem Metadata only Cloudy bag model: convergent perturbation expansion for the nucleon(American Physical Society, 1981) Dodd, L.R.; Thomas, A.W.; Alvarezestrada, R.F.A previously published bound on the probability of finding pions in the dressed nucleon in Chew-Low theory is improved. The proof is then extended to the recently derived cloudy-bag-model Hamiltonian. Together with a bound on the average number of pions (0.9±1.0), our result strongly suggests a rapid convergence of the perturbation expansion in the cloudy bag model.Item Metadata only Low-energy pion scattering in the cloudy-bag model(Institute of Physics, 1981) Thomas, A.W.By applying a unitary transformation to the Lagrangian density of the cloudy-bag model, the author obtains a generalisation of the Weinberg effective Lagrangian for pion-nucleon scattering. The new Lagrangian incorporates the Weinberg-Tomozawa result for s-wave pion scattering from any hadronic bag in a very simple but elegant fashion.Item Metadata only Charge symmetry tested by comparison of π⁺ and π⁻ elastic scattering from deuterium at 143 MeV(American Physical Society, 1982) Masterton, T.G.; Kraushaar, J.J.; Peterson, R.J.; Raymond, R.S.; Ristinen, R.A.; Boudrie, R.L.; Gibson, E.F.; Thomas, A.W.A sensitive test of nuclear charge symmetry has been made by comparing differential cross sections for π+ and π− elastic scattering from deuterium at 143 MeV. Residual charge symmetry breaking effects in the cross section ratio have been parametrized in terms of mass and width differences among the components of the Δ isobar. Accurate absolute π−d differential cross sections were measured for the first time and π+d differential cross sections agree well with other results and with three-body calculations. NUCLEAR REACTIONS H2(π+, π+), H2(π−, π−), Eπ=143 MeV, measured σ(θ). Magnetic spectrograph. Three-body analysis. Charge symmetry breaking parametrized in terms of Δ isobar mass and width differences.Item Metadata only HF Doppler measurements of mesospheric gravity wave momentum fluxes(American Meteorological Society, 1983) Vincent, R.; Reid, I.Recent theoretical studies have emphasized the probable importance of internal gravity waves in balancing the momentum budget of the mesosphere. In this paper, we propose a method by which the vertical flux of horizontal momentum can be measured by ground based radars. The method uses two or more radar beams each offset from the vertical to measure the atmospheric motions by the Doppler technique. Provided there is horizontal homogeneity, the momentum flux is proportional to the difference of the variances of the Doppler velocities measured in each beam. The flux convergence and, hence, the associated body force acting on the atmosphere can be inferred by measuring the flux as a function of height. It is shown that mean wind components can also be measured by this method and, under certain circumstances, so can the horizontal wavelengths and phase velocities of the internal waves. Observations of the vertical flux of zonal momentum made with this technique using an HF radar located near Adelaide, Australia (35°S, 138°E) in May 1981 are discussed. At heights in the range of 80–90 km, a mean upward flux of westward momentum was measured, and from the flux convergence a body force equivalent to an acceleration of the order of −20 m s⁻¹ day⁻¹ is inferred. There wore, however, significant variations in the flux both in direction and magnitude on the scales of the order of hours. Measurements using cross-spectral techniques of the gravity wave horizontal wavelengths and phase velocities suggest that values of ~50 km and 50 m s⁻¹, respectively, are dominant at periods of less than one hour.Item Metadata only A simple model for testing the effects of gravity-wave-produced vertical-oscillations of scattering irregularities on spaced-antenna, horizontal drift measurements(ICSU Scientific Committee on Solar-Terrestrial Physics (SCOSTEP), 1984) Meek, C.; Reid, I.; URSI/SCOSTEP Workshop on Technical Aspects of MST Radar (2nd : 1984 : Urbana, IL, USA)It has been suggested that the velocities produced by the spaced antenna partial-reflection drift experiment may constitute a measure of the vertical oscillations due to short-period gravity waves rather than the mean horizontal flow. The contention is that the interference between say two scatterers, one of which is traveling upuard, and the other down, will create a pattern which sweeps across the ground in the direction (or anti-parallel) of the wave propagation. Since the expected result, viz. spurious drift directions, is seldom, if ever, seen in spaced antenna drift velocities, this speculation is tested in the following model.Item Metadata only Observations of mesospheric wind velocities: 1. Gravity wave horizontal scales and phase velocities determined from spaced wind observations(American Geophysical Union, 1985) Meek, C.; Reid, I.; Manson, A.Horizontal scales and phase velocities of upper middle atmosphere (60–110 km) gravity waves determined from preliminary analysis of spaced wind observations obtained with a dual bistatic radar (Gravnet), based on and operated together with the Saskatoon MF radar are presented. In the observed period range of 10–100 min, horizontal scales increase from values of ∼44 km at 10 min to ∼211 km at 100 min, while observed phase speeds decrease from values of ∼72 m/s at 10 min to ∼34 m/s at 100 min. Typical rms perturbation velocities are ∼5 m/s. Calculation of intrinsic wave parameters indicates that in the intrinsic period range of 10–100 min, horizontal scales increase from values of ∼68 km at 10 min to ∼119 km at 100 min, with intrinsic phase speeds of ∼93 m/s at 10 min and ∼20 m/s at 100 min. The corresponding values of vertical wavelength are 30 km and 6 km, respectively.Item Metadata only Observations of mesospheric wind velocities 2. Cross sections of power spectral density for 48–8 hours, 8–1 hours, and 1 hour to 10 min over 60–110 km for 1981(American Geophysical Union, 1985) Meek, C.; Reid, I.; Manson, A.Cross sections of power spectral density for 1981 between 60–110 km for the 48- to 8 hour and 8- to 1-hour-period bands, and of mean square velocity components in the 10- to 60-min-period band, are compared to cross sections of mean wind. Individual spectra agree well in form and amplitude to similar spectra for other sites when averaged over the entire year, but there are substantial variations in power spectral density in each band over the year. In the 10-min to 8-hour-period band, minima in spectral densities follow the zero line of mean zonal velocity very closely, indicating strong gravity wave mean flow interactions. This, and the variation in gravity wave intensity in general, suggests that gravity wave momentum deposition plays an important role in balancing the heat and momentum budgets of the upper middle atmosphere.Item Metadata only S-wave meson-nucleon scattering in an SU(3) cloudy bag model(American Physical Society, 1985) Veit, E.A.; Jennings, B.K.; Thomas, A.W.; Barrett, R.C.The cloudy bag model (CBM) is extended to incorporate chiral SU(3)×SU(3) symmetry, in order to describe S-wave KN and K¯N scattering. In spite of the large mass of the kaon, the model yields reasonable results once the physical masses of the mesons are used. We use that version of the CBM in which the mesons couple to the quarks with an axial-vector coupling throughout the bag volume. This version also has a meson-quark contact interaction with the same spin-flavor structure as the exchange of the octet of vector mesons. The present model strongly supports the contention that the Λ* (1405) is a K¯N bound state.Item Metadata only KN scattering in the cloudy bag model: s, p, and d waves(American Physical Society, 1985) Veit, E.A.; Thomas, A.W.; Jennings, B.K.s-, p-, and d-wave KN phase shifts are calculated with the cloudy bag model (CBM). The results are in qualitative agreement with phase-shift analysis, except in those partial waves where exotic resonances are claimed to exist. However it seems that it is possible to get good agreement for these waves by just modifying the CBM potential, without including explicitly exotic states.Item Metadata only Gravity wave motions in the upper middle atmosphere (60-110 km)(Elsevier, 1986) Reid, I.Recent improvements in radar techniques have significantly increased their potential for inves- tigating internal atmospheric gravity waves propagating in the upper mesosphere and lower thermosphere. Information relating to the upward flux of horizontal momentum, and hence the mean flow acceleration associated with these waves, is now accessible, as are better estimates of horizontal scales and phase velocities. Long term single site measurements of horizontal velocity have also allowed seasonal variations in mean square velocity components associated with gravity waves to be investigated. Recent results obtained with the Adelaide, Australia (35°S), and Saskatoon, Canada (52°N), MF radars are briefly considered, together with related observations derived from other techniques.Item Metadata only Charge-symmetry breaking in neutron-proton elastic scattering(American Physical Society, 1986) Miller, G.A.; Thomas, A.W.; Williams, A.G.Abstract not available