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The dual-axis radiographic hydrodynamic test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT-II LIA, we measure an emittance higher than predicted by theoretical simulations, and even though this accelerator produces submillimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell codes. The simulations establish that the most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo. [ABSTRACT FROM PUBLISHER]

A novel bidirectional compression electron gun is designed for a W-band sheet beam traveling-wave tube. A parabolic curved cathode and a beam focusing electrode based on spline interpolation curves are proposed to obtain a beam with good quality. Two directional compressions are introduced to reduce the beam loading of cathode. A 30-kV, 0.97-A beam is emitted by a curved 0.112-cm2 cathode with a beam loading of 8.66 A/cm2. The beam at waist position is 1.4 mm $\times0.4$ mm with a compression ratio of 2 and 10 in two directions separately. Studies of beam emittance and sensitivity of beam dynamics to mechanical errors are also carried out to understand the influence of structure parameters on electron gun performance. [ABSTRACT FROM AUTHOR]

Particle-induced X-ray emission is used for determining the elemental composition of materials. This method uses low-energy protons (of several MeV), which can be obtained from high-energy (of tens MeV) accelerators. Instead of manufacturing an accelerator for generating the MeV protons, the use of a PET cyclotron has been suggested for designing the beamline for multipurpose applications, especially for the PIXE experiment, which has a dedicated high-energy (of tens MeV) accelerator. The beam properties of the cyclotron were determined at this experimental facility by using an external beamline before transferring the ion beam to the experimental chamber. We measured the beam profile and calculated the emittance using the pepper-pot method. The beam profile was measured as the beam current using a wire scanner, and the emittance was measured as the beam distribution at the beam dump using a radiochromic film. We analyzed the measurement results and are planning to use the results obtained in the simulations of external beamline and aligned beamline components. We will consider energy degradation after computing the beamline simulation. The experimental study focused on measuring the emittance from the cyclotron, and the results of this study are presented in this paper. [ABSTRACT FROM AUTHOR]

A minimal set vectorial parameterization involving vector space operations is proposed for finite 3D rotations in structural analysis. In this approach, based on the updated Lagrangian description, complex manipulations required to obtain conservative descriptions and well-posed transformation matrices are avoided. In particular, slopes are used instead of rotation parameters to compute the nonlinear representations of the strain measures in the inertial frame of reference. This approach is applied to a geometrically nonlinear formulation for 3D beam elements in the hypotheses of large rotations and small strains. Numerical tests have been carried out to validate the developed technique in the frame structures context. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we describe the first measurements performed during fall of 2010 and the beginning of 2011. We discuss software development, realistic simulations and new hardware improvements of a Multi-Optical Transition Radiation System installed in the beam diagnostics section of the Extraction (EXT) line of ATF2, close to the Multi Wire Scanner System. 2D emittance measurements have been successfully demonstrated and the system is being routinely used for coupling correction. Realistic beam simulations have been made and compared with measurements. A 4D emittance procedure is being prepared and some preliminary measurements have been performed. An improved optical system including a demagnifier lens to improve the beam finding procedure is being designed and will be installed during the autumn 2011 operations period. A systematic measurement campaign will take place after recovery of ATF operations (post the 2011 Tohoku Earthquake), then a comparison with wire scanners can be done. This will be a definitive test of the OTR as a beam emittance diagnostic device, which will provide fast beam emittance measurements with high statistics, giving a low error and a good understanding of emittance jitter and sources. [Copyright &y& Elsevier]

Recent results of identical pion correlations from the NA45/CERES, NA49, and NA57 CERN SPS experiments are discussed including their beam energy and transverse momentum dependence. The emphasis is put on the Hanbury-Brown Twiss (HBT) pion correlations analyzed with respect to the reaction plane orientation reported by the CERES Collaboration D. Adamova et al., Phys. Rev. C78, 064901 (2008). The mean free path of pions at freeze-out D. Adamova et al., Phys. Rev. Lett. 90, 022301 (2003) is presented updated by the recent results from the SPS experiments. [ABSTRACT FROM AUTHOR]

We report large current- and temperature-induced beam-steering effects, observed in the far-field distribution of InP-based quantum-cascade lasers emitting around 7.8-μm wave-length operated in pulsed mode. Changing the temperature within a narrow range of ∼ 10°C around room-temperature leads to a change in the direction of the output beam, as given by the central lobe in the far-field intensity distribution, from +11° to -13° as measured relative to the resonator axis. This beam steering effect is linked to changes in the lateral mode distribution, as revealed by time-resolved spectroscopy of the lasing spectrum. [ABSTRACT FROM AUTHOR]

A new laser-wire has been installed in the extraction line of the ATF at KEK. It aims at demonstrating that laser-wires can be used to measure micrometre scale beam size. In parallel, studies have been made to specify a laser suitable for the ILC laser-wires. [ABSTRACT FROM AUTHOR]

We study the expected performance of the proposed fundamental neutron physics beamline at the upgraded High Flux Isotope Reactor at Oak Ridge National Laboratory. A curved neutron guide transmits the neutrons from the new cold source into a guide hall. A novel feature of the proposed guide is the use of vertical focussing to increase the flux for experiments that require relatively small cross-section beams. We use the simulation code IB to model straight, multi-channel curved, and tapered guides of various m values. Guide performance for the current NPDGamma and proposed Abbas experiments is evaluated. [ABSTRACT FROM AUTHOR]

It is shown that the Lorentz transformation cannot in general be formally applied to potentials and fields of particles locked in a certain region. In particular, this property relates to nucleons in nuclei and to particles and nuclei in storage rings. Even if they move with high velocities, their electric fields are defined by the Coulomb law. The result obtained is rather important for the planned deuteron electric-dipole-moment experiment in storage rings. [ABSTRACT FROM AUTHOR]

The article discusses the approval by the U.S. Department of Energy (DOE) of a facility to generate rare isotopes in the fields of nuclear physics, astrophysics, and medical diagnostics. Michigan State University and Argonne National Laboratory in Illinois, competed to host the Facility of Rare Isotope Beams (FRIB). An brief overview of the facility's linear accelerator, which is the centerpiece of the FRIB, is presented.