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Detector Characterization
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
The unique properties of synchrotron radiation can be summarized as follows: Unique production mechanism in that it can be precisely describedHigh brightness and high intensity, many orders of magnitude more than that of X-rays produced in conventional X-ray tubesWide tuneability in energy/wavelength by monochromatization (from sub-eV up to MeV)High collimation, small angular divergence of the beamLow emittance, the product of source cross-section and small solid angle of emissionHigh level of polarization (linear or elliptical)Pulsed light emission with durations of 1 ns or less
Proton and Ion Laser Plasma Acceleration
Published in Andrei Seryi, Unifying Physics of Accelerators, Lasers and Plasma, 2015
Discuss and develop a plan to create a 250 MeV proton source based on plasma acceleration, aiming for it to be applied in the medical field. Select approximate laser parameters and target parameters, and discuss their requirements. Discuss and select a method for energy monochromatization or energy collimation/selection. Describe why you selected these particular values of certain parameters (for target or laser, collimation or monochromatization system, etc.).
Relativistic effects in the interaction of fast charged particles with graphene
Published in Radiation Effects and Defects in Solids, 2020
Keenan Lyon, Kamran Akbari, Zoran L. Miskovic
Considering the dynamic response of graphene in the frequency range from the near infrared to the far ultraviolet, corresponding to electron energy losses in the ∼1–50 eV range (6,16,22), we have used several conductivity models to describe the interband electron transitions involving both the π and σ electron bands in graphene. It should be mentioned that, in this range of energy losses, the effects of doping in graphene are not observable under typical STEM conditions, i.e.without abberation correction and the beam monochromatization (7,8), so our models were formulated for intrinsic graphene. We have first developed a phenomenological, two-fluid hydrodynamic (HD) model, which has successfully reproduced the π and peaks in the experimental EELS data for SLG and MLG (4,6,27). The range of applicability of that model was subsequently extended to lower energies (22), giving rise to the extended HD (eHD) model conductivity , described in subsection 3.1. The parameters appearing in were calibrated by a comparison with the results of ab initio calculations of the optical conductivity of intrinsic graphene using the PW-TDDFT-k-ω approach, as described in subsection 3.1 (16,22,24,25).
Distinctive applications of synchrotron radiation based X-ray Raman scattering spectroscopy: a minireview
Published in Instrumentation Science & Technology, 2021
The experimental setup for a typical XRS spectroscopy is presented in Figure 3. In the experiment, the first monochromatization after the undulator is performed through a double-crystal monochromator (DCM) which takes the excessive heat of the beam and selects the desired energy. A channel-cut crystal (high resolution monochromator; HRM) can be used in need of further monochromatization. Monochromatized X-rays are focused on the sample both in vertical and horizontal directions using Kirkpatrick-Baez (KB) mirrors. Inelastically scattered X-rays by the sample are energy analyzed by spherically bent multi-crystal analyzers and focused on the detector. In Figure 3, only one set of crystal analyzers is shown.[17] Several groups of spherically bent analyzers are placed at different locations on the Rowland circle so that the required momentum transfer range can be covered.[16] Since the energy resolution, background, momentum transfer and efficiency of each analyzer within an analyzer set may vary, data evaluation must be done analyzer by analyzer. For this purpose, two-dimensional pixel detectors are utilized which allow to record the focus of each analyzer on a different spot of the detector area.[18] Point-to-point focusing of bent crystal analyzers on two-dimensional detector enables the imaging of the sample and its environment.[13] This feature can be utilized to discriminate the scattering from air, sample chamber walls and sample gas itself, while working with samples in the gas phase[18] and also simplifies the alignment of the samples in complex conditions, e.g., diamond anvil cells. In order to make X-ray imaging possible in XRS experiments, an area detector with pixel size of 55 × 55 μm2 or less is required.[22]