A large acceptance lead-scintillator time-of-flight (TOF) wall has been developed to detect photons, neutrons, and charged particles produced in meson-photoproduction experiments on the proton and on the neutron. A TOF resolution of 600 ps and a position resolution of 11 x 18 cm(2) (full-width at half-maximum) have been achieved. The wall has been successfully used in eta and pi(+) photoproduction experiments as a photon and a neutron detector. This paper reports its design, calibration and performance. (C) 2002 Elsevier Science B.V. All rights reserved
We report the observation of coherent emission from a Cherenkov free-electron laser driven by a 5-MeV radio-frequency microtron. Power up to 50 W in pulses of 4-fis duration has been generated at the wavelengths of 1.6 and 0.9 mm using two different dielectric-loaded waveguides.PACS numbers: 42.55.Tb, 41.70.+t Slow-wave structures, which achieve velocity synchronism between the propagating wave and the interacting electron beam, are considered as potential candidates for the generation of power in the millimeter and submillimeter regions of the spectrum, since they overcome many of the problems related to the excitation of microwave cavities with dimensions of the order of the wavelength.A number of experiments exploiting the emission of Cherenkov radiation in dielectric-loaded waveguides have been performed in the past, x mainly in the millimeter region utilizing electron beams at energy < 1 MeV. In this type of device a beam of relativistic electrons passes at grazing incidence above the surface of a dielectric-loaded waveguide, exciting TM-like surface waves. 2 The longitudinal component of the evanescent electric field causes a bunching of the electrons, which give rise to stimulated emission. 3 In the synchronism condition for a single-slab geometry 2 the radiation is emitted at a wavelength given by
X=27tdy(e-l)/e(1)in the approximation y^>\, X^>d y where d is the film thickness, e its dielectric constant, and y the relativistic factor of the electrons. The coupling efficiency C between a single electron and the TM wave is expressed by an exponential behav-2
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