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Search Results: 1 - 10 of 450012 matches for " C. J. Batty "
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Experiments with $Ξ^-$ atoms
C. J. Batty,E. Friedman,A. Gal
Physics , 1998, DOI: 10.1103/PhysRevC.59.295
Abstract: Experiments with $\Xi^-$ atoms are proposed in order to study the nuclear interaction of $\Xi$ hyperons. The production of $\Xi^-$ in the ($K^{-}$, $K^{+}$) reaction, the $\Xi^-$ stopping in matter, and its atomic cascade are incorporated within a realistic evaluation of the results expected for $\Xi^-$ X-ray spectra across the periodic table, using an assumed $\Xi$-nucleus optical potential $V_{opt}$. Several optimal targets for measuring the strong-interaction shift and width of the X-ray transition to the `last' atomic level observed are singled out: F, Cl, I, Pb. The sensitivity of these observables to the parameters of $V_{opt}$ is considered. The relevance of such experiments is discussed in the context of strangeness -2 nuclear physics and multistrange nuclear matter. Finally, with particular reference to searches for the $H$ dibaryon, the properties of $\Xi^-d$ atoms are also discussed. The role of Stark mixing, its effect on $S$ and $P$ state capture of $\Xi^-$ by the deuteron, together with estimates of the resulting probability for producing the $H$ dibaryon are considered in detail.
Unified optical-model approach to low-energy antiproton annihilation on nuclei and to antiprotonic atoms
C. J. Batty,E. Friedman,A. Gal
Physics , 2000, DOI: 10.1016/S0375-9474(00)00608-4
Abstract: A successful unified description of $\bar p$ nuclear interactions near E=0 is achieved using a $\bar p$ optical potential within a folding model, $V_{{\rm opt}} \sim \bar v * {\rho}$, where a $\bar p p$ potential $\bar v$ is folded with the nuclear density $\rho$. The potential $\bar v$ fits very well the measured $\bar p p$ annihilation cross sections at low energies ($p_L < 200$ MeV/c) and the $1s$ and $2p$ spin-averaged level shifts and widths for the $\bar p$H atom. The density-folded optical potential $V_{{\rm opt}}$ reproduces satisfactorily the strong-interaction level shifts and widths over the entire periodic table, for $A > 10$, as well as the few low energy $\bar p$ annihilation cross sections measured on Ne. Both $\bar v$ and $V_{{\rm opt}}$ are found to be highly absorptive, which leads to a saturation of reaction cross sections in hydrogen and on nuclei. Predictions are made for $\bar p$ annihilation cross sections over the entire periodic table at these very low energies and the systematics of the calculated cross sections as function of $A$, $Z$ and $E$ is discussed and explained in terms of a Coulomb-modified strong-absorption model. Finally, optical potentials which fit simultaneously low-energy $\bar p - ^4$He observables for $E < 0$ as well as for $E > 0$ are used to assess the reliability of extracting Coulomb modified $\bar p$ nuclear scattering lengths directly from the data. The relationship between different kinds of scattering lengths is discussed and previously published systematics of the $\bar p$ nuclear scattering lengths is updated.
Saturation of low-energy antiproton annihilation on nuclei
A. Gal,E. Friedman,C. J. Batty
Physics , 2000, DOI: 10.1016/S0370-2693(00)01040-6
Abstract: Recent measurements of very low-energy ($p_{L}<100$ MeV/c) $\bar p$ annihilation on light nuclei reveal apparent suppression of annihilation upon increasing the atomic charge $Z$ and mass number $A$. Using $\bar p$-nucleus optical potentials $V_{{\rm opt}}$, fitted to $\bar p$-atom energy-shifts and -widths, we resolve this suppression as due to the strong effective repulsion produced by the very absorptive $V_{{\rm opt}}$. The low-energy $\bar p$-nucleus wavefunction is kept substantially outside the nuclear surface and the resulting reaction cross section saturates as function of the strength of Im $V_{{\rm opt}}$. This feature, for $E >0$, parallels the recent prediction, for $E < 0$, that the level widths of $\bar p$ atoms saturate and, hence, that $\bar p$ deeply bound atomic states are relatively narrow. Antiproton annihilation cross sections are calculated at $p_{L}=57$ MeV/c across the periodic table, and their dependence on $Z$ and $A$ is classified and discussed with respect to the Coulomb focussing effect at very low energies.
The antinucleon-nucleon interaction at low energy : annihilation dynamics
E. Klempt,C. Batty,J. -M. Richard
Physics , 2005, DOI: 10.1016/j.physrep.2005.03.002
Abstract: The general properties of antiproton-proton annihilation at rest are presented, with special focus on the two-meson final states. The data exhibit remarkable dynamical selection rules : some allowed annihilation modes are suppressed by one order of magnitude with respect to modes of comparable phase-space. Various phenomenological analyses are reviewed, based on microscopic quark dynamics or symmetry considerations. The role of initial- and final-state interaction is also examined.
Haemostatic problems in liver surgery: A review
P.C Gordon, D.J Batty
Southern African Journal of Anaesthesia and Analgesia , 2009,
Abstract: No Abstract
On series of sectorial forms
C. J. K. Batty,A. F. M. ter Elst
Mathematics , 2013,
Abstract: We prove a convergence theorem for partial sums of sectorial forms with vertex zero and a common semi-angle. As an example we prove an absorption theorem for sectorial forms.
Optimal energy decay in a one-dimensional coupled wave-heat system
C. J. K. Batty,L. Paunonen,D. Seifert
Mathematics , 2015,
Abstract: We study a simple one-dimensional coupled wave-heat system and obtain a sharp estimate for the rate of energy decay of classical solutions. Our approach is based on the asymptotic theory of $C_0$-semigroups and in particular on a result due to Borichev and Tomilov (Math. Ann., 2010), which reduces the problem of estimating the rate of energy decay to finding a growth bound for the resolvent of the semigroup generator. This technique not only leads to an optimal result, it is also simpler than the methods used by other authors in similar situations.
Electro-thermal Modelling of Monolithic and Hybrid Microwave and Millimeter Wave IC's
W. Batty,A. J. Panks,R. G. Johnson,C. M. Snowden
VLSI Design , 2000, DOI: 10.1155/2000/86517
Abstract: The first completely physical electro-thermal model is presented that is capable of describing the large signal performance of MESFET- and HEMT-based, high power microwave and millimeter wave monolithic and hybrid ICs, on timescales suitable for CAD. The model includes the effects of self-heating and mutual thermal interaction on active device performance with full treatment of all thermal non linearities. The electrical description is provided by the rapid quasi-2D Leeds Physical Model and the steady-state global thermal description is provided by a highly accurate and computationally inexpensive analytical thermal resistance matrix approach. The order of the global thermal resistance matrix describing 3-dimensional heat flow in complex systems, is shown to be determined purely by the number of active device elements, not the level of internal device structure. Thermal updates in the necessarily iterative, fully coupled electro-thermal solution, therefore reduce to small matrix multiplications implying orders of magnitude speed-up compared to the use of full numerical thermal solutions capable of comparable levels of detail and accuracy.
A fresh look at eta2(1645), eta2(1870), eta2(2030) and f2(1910) in pbar-p -> eta + 3pizero
A. V. Anisovich,C. J. Batty,D. V. Bugg,V. A. Nikonov,A. V. Sarantsev
Statistics , 2010, DOI: 10.1140/epjc/s10052-010-1511-3
Abstract: There is a large discrepancy between results of Crystal Barrel and WA102 for the branching ratio R = BR[eta2(1870)->a2(1320)pi]/ BR[eta2(1870)->f2(1270)eta]. An extensive re-analysis of the Crystal Barrel data redetermines branching ratios for decays of eta2(1870), eta2(1645), eta2(2030) and f2(1910). This re-analysis confirms a small value for R of 1.60+-0.39, inconsistent with the value 32.6+-12.6 of WA102. The likely origin of the discrepancy is that the WA102 data contain a strong f2(1910)->a2-pi signal as well as eta2(1870). There is strong evidence that the eta2(1870) has resonant phase variation. A peak in f2(1270)a0(980) confirms closely the parameters of the a2(2255) resonance observed previously. A peak in eta2(2030)-pi is interpreted naturally in terms of pi2(2245) with reduced errors for mass and width M=2285+-20(stat)+-25(syst) MeV, Gamma=250+-20(stat)+-25(syst) MeV.
Data on pbar-p -> etaprime-pizero-pizero for masses 1960 to 2410 MeV/c^2
A. V. Anisovich,C. A. Baker,C. J. Batty,D. V. Bugg,C. Hodd,V. A. Nikonov,A. V. Sarantsev,V. V. Sarantsev,B. S. Zou
Physics , 2011, DOI: 10.1016/S0370-2693(00)01019-4
Abstract: Data on pbar-p -> etaprime(958)-pizero-pizero are presented at nine pbar momenta from 600 to 1940 MeV/c. Strong S-wave production of f_2(1270)-etaprime is observed, requiring a J^{PC} = 2^{-+} resonance with mass M = 2248+-20 MeV, Gamma = 280+-20 MeV.
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