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| THPPH055 |
Nonintercepting Beam Size and Position Monitor Using ODR for X-Ray FELs
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710 |
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- A. H. Lumpkin, W. Berg, N. Sereno, B. X. Yang, C. Yao
ANL, Argonne, Illinois
- D. W. Rule
NSWC, West Bethesda, Maryland
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Interest in nonintercepting (NI) beam size and position diagnostics in the undulators of x-ray free-electron lasers (XFELs) is driven by the requirement of beam-emittance matching, as well as by the need to minimize radiation damage to the undulator's permanent magnets from scattered beam produced by the insertion of converter screens. For these reasons, our investigations on optical diffraction radiation (ODR) as NI relative beam size and position diagnostics are particularly relevant to XFELs. We report the extensions of our studies at 7-GeV beam energy to aspects of the vertical and horizontal polarization components of the ODR near-field and far-field images. The near-field, vertically polarized data are particularly interesting since the vertical field lines at the metal more directly reflected the actual beam sizes. Although our experiments to date are with larger beams and impact parameters of 1-2 mm, our analytical model indicates that this technique scales with beam size and has sensitivity at the 20- to 50-micron regime with an impact parameter, d = 5 times σ-y =100 microns. This is the x-ray FEL intraundulator beam size regime.
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