120 research outputs found

    Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching a Puzzle by Exclusive and Kinematically Complete Measurements

    Get PDF
    The ABC effect - a puzzling low-mass enhancement in the ππ\pi\pi invariant mass spectrum - is well-known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on first exclusive and kinematically complete measurements of the most basic double pionic fusion reaction pndπ0π0pn \to d \pi^0\pi^0 at 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (ππ)I=L=0(\pi\pi)_{I=L=0} channel phenomenon associated with both a resonance-like energy dependence in the integral cross section and the formation of a ΔΔ\Delta\Delta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data

    Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

    Full text link
    This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski, Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy), Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy

    Exclusive measurement of two-pion production in the dd --> 4Hepipi reaction

    Get PDF
    The results from the first kinematically complete measurement of the dd --> 4Hepipi reaction are reported. The aim was to investigate a long standing puzzle regarding the origin of the peculiar pipi-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 pipi-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--> dpi sub-processes.Comment: 20 pages including 18 figure

    Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

    Full text link
    To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected.Comment: 216 page

    Leukodystrophies: a proposed classification system based on pathological changes and pathogenetic mechanisms

    Get PDF

    THE STRUCTURE OF THE SCHWANN CELL AND ITS RELATION TO THE AXON IN CERTAIN INVERTEBRATE NERVE FIBERS

    No full text
    corecore