Search results for "Accelerator Physics"
showing 10 items of 1294 documents
Reference beam dynamics layout for the SC CW heavy ion HELIAC at GSI
2020
Abstract The standalone superconducting continuous wave heavy ion linac HELIAC (HElmholtz LInear ACcelerator) is a common project of GSI Helmholtz Centre for Heavy Ion Research and Helmholtz Institute Mainz (HIM) under key support of Goethe University Frankfurt (IAP) and in collaboration with National Research Nuclear University MEPhI and NRC “Kurchatov Institute” ITEP. In 2017 the first superconducting section of the linac has been successfully commissioned and extensively tested with beam at GSI. The measurements sufficiently present the capability of 216.816 MHz multi-gap Crossbar H-mode (CH) DTL-structures. An acceleration of heavy ions up to the design beam energy and beyond has been r…
Emittance measurements with optical transition radiation at the S-DALINAC
2020
Abstract A new emittance measurement system has been installed at the superconducting, recirculating electron accelerator S-DALINAC. It is based on the quadrupole-scan technique and beam profile measurements with optical transition radiation. A first demonstration of this setup has been conducted as part of the beam-based alignment of an SRF cavity. The corresponding emittance measurement is described here, and the following data evaluation is discussed.
Total photoabsorption cross section for4He from 200 to 800 MeV
1997
The total photoabsorption cross section for ${}^{4}$He has been measured for the first time over a wide photon energy range (200 MeV$l~{E}_{\ensuremath{\gamma}}l~$800 MeV). By using the large acceptance detector DAPHNE at the tagged photon facility of the MAMI microtron in Mainz high precision results with small systematic errors were obtained. This measurement shows that ${}^{4}$He has a behavior similar to heavy nuclei and, in particular, a reduction of the cross section with respect to the lighter nuclei is found for ${E}_{\ensuremath{\gamma}}g$600 MeV.
The energy calibration of LEP in the 1993 scan
1995
This report summarizes the procedure for providing the absolute energy calibration of the LEP beams during the energy scan in 1993. The average beam energy around the LEP ring was measured in 25 calibrations with the resonant depolarization technique. The time variation of this average beam energy is well described by a model of the accelerator based on monitored quantities. The absolute calibration of the centre of mass energies of the off-peak points is determined with a precision of 2 parts in 10(5) resulting in a systematic error on the Z-mass of about 1.4 MeV and on the Z-width of about 1.5 MeV.
Top-quark pair production cross-section measurements with the ATLAS detector
2019
Measurements of the inclusive and differential top-quark pair production cross sections in proton-proton collisions with the ATLAS detector at the Large Hadron Collider at center-of-mass energies of 8 TeV and 13 TeV are presented. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. Differential measurements of the kinematic properties of the top-quark production are also discussed. These measurements, including results using boosted tops, probe our understanding of top-quark pair production in the TeV regime.
Compact dielectric reflective elements I Half-sphere concentrators of radially emitted light
1994
Optical designs of aspheric internally reflective concentrators of divergent light emitted within a spatial angle of 2n sr are proposed and discussed. Four types of solid transparent element are considered: the divergence angle reducer, the small-spot illuminator, the point focuser, and the collimator. The output beam aperture in all cases is comparable with the light-source external dimensions. Expressions describing the profiles of beam-transforming surfaces and results from experiments with model devices are presented.
Plasmon-driven Bessel beams
2012
We report on subwavelength diffraction-free beams with grazing propagation in metal-dielectric devices. The nondiffracting beams are resonantly transmitted through the nanostructured medium leading to light confinement and wave amplification around the beam axis.
Spatial and spectral nonlinear shaping of multimode waves
2016
We demonstrate a novel nonlinear dynamics of multimode fibers that reshapes their spectral and spatial beam profiles, based on spatiotemporal modulation instability. Sidebands ranging from the visible to the near-infrared are carried by one and the same spatial bell-shaped profile.
Nonlinear Multimode Fiber Optics
2018
We overview recent advances in the nonlinear optics of multimode optical fibers, including ultrabroadband sideband and supercontinuum generation, Kerr and Raman beam cleanup, modal modulation instabilities, four wave mixing, and second harmonic beam cleaning.
Control of nonlinear instabilities in Bessel beams using shaped longitudinal intensity profiles
2017
International audience; We show that tailored longitudinal intensity shaping of a non-diffracting Bessel beam can strongly reduce four wave mixing induced oscillations and stabilize nonlinear propagation at ablation-level intensities