62 research outputs found

    An explanation of the ABC enhancement in the dd -> alpha X reaction at intermediate energies

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    The dd -> alpha X reaction is studied in a model where each pair of nucleons in the projectile and target deuterons undergoes pion production through the NN -> d pi reaction. The condition that the two deuterons fuse to form an alpha-particle then leads to peaks at small missing masses, the well-known ABC enhancement, but also a broad structure around the maximum missing mass. With a simplified input amplitude the model gives a quantitative description of both the alpha-particle momentum and angular distributions for a deuteron beam energy of 1250 MeV.Comment: 10 pages, Latex2e, 1 eps figure, submitted to Phys. Lett.

    Extended sudden approximation model for high-energy nucleon removal reactions

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    A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen \cite{Anne2}, the nucleon-removal cross section and the full 3-dimensional momentum distributions of the core fragments including absorption, diffraction, Coulomb and nuclear-Coulomb interference amplitudes, have been calculated. The Coulomb breakup has been treated to all orders for the dipole interaction. The model has been compared to experimental data for a range of light, neutron-rich psd-shell nuclei. Good agreement was found for both the inclusive cross sections and momentum distributions. In the case of 17^{17}C, comparison is also made with the results of calculations using the transfer-to-the-continuum model. The calculated 3-dimensional momentum distributions exhibit longitudinal and transverse momentum components that are strongly coupled by the reaction for s-wave states, whilst no such effect is apparent for d-waves. Incomplete detection of transverse momenta arising fromlimited experimental acceptances thus leads to a narrowing of the longitudinal distributions for nuclei with significant s-wave valence neutron configurations, as confirmed by the data. Asymmetries in the longitudinal momentum distributions attributed to diffractive dissociation are also explored.Comment: 16 figures, submitted to Phys. Rev.

    Radiative Decay Width Measurements of Neutral Kaon Excitations Using the Primakoff Effect

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    We produce a sample consisting of 147 candidate events, with minimal backgrounds, of the mixed axial vector pair K1(1270)-K1(1400) by exciting Kl's in the Coulomb field of lead and report the first measurements of the radiative widths Gamma_r(K1(1400)) = 280.8+-23.2(stat)+-40.4(syst) keV and Gamma_r(K1(1270)) = 73.2+- 6.1(stat)+-28.3(syst) keV. We also place 90% CL upper limits Gamma_r(K*(1410)) < 52.9 keV for the vector state and Gamma_r(K2*(1430)) < 5.4 keV for the tensor state. These measurements allow for significant tests of quark-model predictions of radiative widths for the low-lying vector mesons.Comment: PRL-size article, 4 figure

    A review of the optical properties of alloys and intermetallics for plasmonics

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    Alternative materials are required to enhance the efficacy of plasmonic devices. We discuss the optical properties of a number of alloys, doped metals, intermetallics, silicides, metallic glasses and high pressure materials. We conclude that due to the probability of low frequency interband transitions, materials with partially occupied d-states perform poorly as plasmonic materials, ruling out many alloys, intermetallics and silicides as viable. The increased probability of electron-electron and electron-phonon scattering rules out many doped and glassy metals.Comment: 26 pages, 10 figures, 3 table

    A taste of dark matter: flavour constraints on pseudoscalar mediators

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    STRONG COUPLING EXPANSION OF LATTICE GAUGE-THEORIES AT FINITE TEMPERATURE

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    FALDT G, Petersson B. STRONG COUPLING EXPANSION OF LATTICE GAUGE-THEORIES AT FINITE TEMPERATURE. NUCLEAR PHYSICS B. 1986;265(1):197-222

    DECAYS K-]PIGAMMAGAMMA AND K+-]PI+PIO IN ETA-POLE APPROXIMATION

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    FALDT G, Petersson B, PILKUHN H. DECAYS K-]PIGAMMAGAMMA AND K+-]PI+PIO IN ETA-POLE APPROXIMATION. Nuclear Physics B. 1967;3(3):234-240

    The reaction p+3^3He π+\rightarrow\pi^++4^4He

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    The reaction p+3^3He π+\rightarrow\pi^++4^4He

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