Cathodoluminescence (CL) spectra from silicon doped and undoped wurtzite n-type GaN have been measured in a SEM under a wide range of electron beam excitation conditions, which include accelerating voltage, beam current, magnification, beam diameter, and specimen temperature. The CL intensity dependence on excitation density was analyzed using a power-law model (I CL proportional, variant J m )...

The temporal structure of the storage-ring free-electron laser at Elettra shows high sensitivity to electron-beam instabilities. In fact, even small beam perturbations may affect the FEL dynamics and periodically switch off the laser. In order to improve the FEL operation and performance, different and complementary feedback systems have been activated. This paper reports on their beneficial ef...

A low energy ion beam system for space charge compensation (SCC) experiments was developed and evaluated. This system was designed for observation of SCC of a positive ion beam with an electron beam. The system consisted of the ion source chamber and the SCC experiment chamber. The ion source chamber was equipped with the compact microwave ion source for low voltage extraction. Ion current at i...

A simple quasi-analytic model is developed for the dynamics of electron cloud generated by synchrotron radiation of the beam in the LHC beam pipe. The model allows to obtain a multipacting condition for the LHC parameters, takes into account the space charge effect and predicts an equilibrium density of the electrons. Based on this model, we find the electron lifetime and estimate the energy de...

We consider two possible schemes for generation and detection of a monoenergetic directed beam of neutrinos which may have application to neutrino communication. First, we consider generation of a directed neutrino beam using electron capture beta decay in hydrogen-like ions. Next, we suggest detection of a directed neutrino beam using resonant absorption of a neutrino by a bare nucleus with th...

By using the OTR angular distribution property [1], it is possible to extract the energy and the angular dispersion of several kinds of beam [2]. Recently, Le Sage et al. [3] succeeded in producing a transverse phase-space mapping of a 100 MeV electron beam by coupling an interferometric measurement and a ’’mask’’ technique. We present the first OTR time resolved angular distribution measuremen...

We report detailed measurements of the transverse phase space distortions induced by magnetic chicane compression of a high brightness, relativistic electron beam to subpicosecond length. A strong bifurcation in the phase space is observed when the beam is strongly compressed. This effect is analyzed using several computational models and is correlated to the folding of longitudinal phase space...

The Relativistic Electron Facility for Education and Research (REFER) at Hiroshima University accepts a 150 MeV electron beam from a microtron, the injector to the 700 MeV storage ring of the Hiroshima Synchrotron Research Center, and keep it circulating for 2.5ms without a RF acceleration. It acts as a beam stretcher and has been used for the following researches: 1) X-ray generation from an i...