J Synchrotron Radiat. 2014 Sep;21:1194-9. doi: 10.1107/S1600577514012302. Epub 2014 Jul 31.

A short-pulse X-ray beamline for spectroscopy and scattering.

Journal of synchrotron radiation

R Reininger, E M Dufresne, M Borland, M A Beno, L Young, P G Evans

PMID: 25178012 DOI: 10.1107/S1600577514012302

Abstract

Experimental facilities for picosecond X-ray spectroscopy and scattering based on RF deflection of stored electron beams face a series of optical design challenges. Beamlines designed around such a source enable time-resolved diffraction, spectroscopy and imaging studies in chemical, condensed matter and nanoscale materials science using few-picosecond-duration pulses possessing the stability, high repetition rate and spectral range of synchrotron light sources. The RF-deflected chirped electron beam produces a vertical fan of undulator radiation with a correlation between angle and time. The duration of the X-ray pulses delivered to experiments is selected by a vertical aperture. In addition to the radiation at the fundamental photon energy in the central cone, the undulator also emits the same photon energy in concentric rings around the central cone, which can potentially compromise the time resolution of experiments. A detailed analysis of this issue is presented for the proposed SPXSS beamline for the Advanced Photon Source. An optical design that minimizes the effects of off-axis radiation in lengthening the duration of pulses and provides variable X-ray pulse duration between 2.4 and 16 ps is presented.

Keywords: X-ray beamline; picosecond X-ray pulses; time-resolved spectroscopy and scattering

Publication Types

• Journal Article
• Research Support, U.S. Gov't, Non-P.H.S.