title: The LCLS variable-energy hard X-ray single-shot spectrometer.
abstract: The engineering design, implementation, operation and performance of the new variable-energy hard X-ray single-shot spectrometer (HXSSS) for the LCLS free-electron laser (FEL) are reported. The HXSSS system is based on a cylindrically bent Si thin crystal for dispersing the incident polychromatic FEL beam. A spatially resolved detector system consisting of a Ce:YAG X-ray scintillator screen, an optical imaging system and a low-noise pixelated optical camera is used to record the spectrograph. The HXSSS provides single-shot spectrum measurements for users whose experiments depend critically on the knowledge of the self-amplified spontaneous emission FEL spectrum. It also helps accelerator physicists for the continuing studies and optimization of self-seeding, various improved mechanisms for lasing mechanisms, and FEL performance improvements. The designed operating energy range of the HXSSS is from 4 to 20 keV, with the spectral range of order larger than 2% and a spectral resolution of 2 × 10(-5) or better. Those performance goals have all been achieved during the commissioning of the HXSSS.
authors.affiliation: Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: David
authors.initials: D
authors.lastname: Rich
authors.affiliation: Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: Diling
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: James
authors.initials: J
authors.lastname: Turner
authors.affiliation: Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: Dehong
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Hill
authors.affiliation: Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Feng
keywords: X-ray; bent thin crystal; free-electron laser (FEL); single shot; spectrometer; transmissive; variable energy