WE1 — Wednesday Session 1 (14-Sep-22 09:00—10:30)
Chair: L. Bobb, DLS, Oxfordshire, United Kingdom
Paper
Title
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WE1I1
First Observation of Quasi-Monochromatic Optical Cherenkov Radiation in a Dispersive Medium (Quartz)
A.I. Novokshonov
DESY, Hamburg, Germany
Spectral properties of optical Cherenkov radiation (ChR) were studied both theoretically and experimentally. This type of radiation has a continuous spectral distribution which allows to use it in different fields of physics. By exploiting the frequency dependence of the target permittivity it is possible to observe quasi-monochromatic radiation. A theoretical model based on a surface current approach is presented. In order to test the predictions, an experiment was carried out using 855 MeV electrons and a 0.2 mm thick quartz target as radiator. Quasi-monochromatic ChR was observed with a spectrometer, and tilting the radiator crystal offered the possibility to tune the radiation wavelength. The monochromatization effect is attributed to the frequency dependence of the quartz permittivity, and taking into account the refraction law it is possible to deduce a dispersion relation which connects ChR wavelength and target tilt angle for fixed observation angle. Dispersion relation and model description are confirmed in the experiment. Exploiting the ChR monochromatization mechanism might offer versatile tools which can find applications in beam diagnostics.
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An X-Ray Beam Property Analyzer Based on Dispersive Crystal Diffraction
366
N. Samadi, G. Lovric, C. Ozkan Loch
PSI, Villigen PSI, Switzerland
X. Shi
ANL, Lemont, Illinois, USA
The advance in low-emittance x-ray sources urges the development of novel diagnostic techniques. Existing systems either have limited resolution or rely heavily on the quality of the optical system. An x-ray beam property analyzer based on a multi-crystal diffraction geometry was recently introduced. By measuring the transmitted beam profile of a dispersive Laue crystal downstream of a double-crystal monochromator, the system can provide a high-sensitivity characterization of spatial source properties, namely, size, divergence, position, and angle in the diffraction plane of the system at a single location in a beamline. In this work, we present the experimental validation at a super-bending magnet beamline at the Swiss Light Source and refine the method to allow for time-resolved characterization of the beam. Simulations are then carried out to show that the system is feasible to characterize source properties at undulator beamlines for fourth-generation light sources.
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High Accuracy Measurement of the Absolute Energy by Synchrotron Radiation Interferometry with Relativistic Electrons
P. Klag, P. Achenbach
KPH, Mainz, Germany
Funding:Supported by DFG (PO 256/7-1) Supported by the European Union’s Horizon 2020 programme, No 824093 The Mainz Microtron is an electron accelerator, which delivers electron energies up to 1.6 GeV, with a small spread of the energy <13keV. Besides a small energy spread, the high quality of the beam allows producing high coherent synchrotron radiation. The light from two spatially separated and movable light sources (undulators) can be superimposed to render an interference pattern. The ideal applications are high accuracy absolute energy measurements of the relativistic electrons. Experiments have been carried out at 180 MeV and 195 MeV. The radiation lies in the optical range where also Fresnel Diffraction patterns occur, which features allow very precise alignment control.
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