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[en] With the 23 December installation of its final cryomodule containing eight accelerating cavities, the superconducting Continuous Electron Beam Accelerating Facility (CEBAF) machine at Newport News, Virginia, is all but complete. Each of the two linacs in the recirculating machine now has its full 20-cryomodule complement. CEBAF uses two antiparallel linacs linked by semicircular arcs. Beam will be recirculated five times, attaining energies up to about 6 GeV
[en] Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive π"+ electroproduction reaction γ*p→nπ"+. The results were obtained from scattering of 6-GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Laboratory. The kinematic range covered is 1.1 < W < 3 GeV and 1 < Q"2 < 6GeV"2. Results were obtained for about 6000 bins in W, Q"2, cos(θ*), and Φ*. Except at forward angles, very large target-spin asymmetries are observed over the entire W region. Reasonable agreement is found with phenomenological fits to previous data for W < 1.6 GeV, but very large differences are seen at higher values of W. A generalized parton distributions (GPD)-based model is in poor agreement with the data. As a result, when combined with cross-sectional measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of Q"2, for resonances with masses as high as 2.4 GeV.