SXR beamline layout in hutch 1 and hutch 2 of the LCLS Near Experimental Hall. Note that the interface valve denotes the coordinate origin [Z = 0.0 m]. The second photon stopper (S2b) which is located in hutch 2 is introduced in Sec. II A. With S2b closed, access to hutches 1 and 2 is allowed to personnel even with S2 (not shown) open allowing radiation onto S2b. However, because the beam can be focused to a spot exceeding the damage threshold for B4C there are no personnel permitted in hutch 2 while S2b is open.
The transmission sample system (TSS) may be used to introduce transmission samples upstream of the monochromator. It is used for calibrating the wavelength selection of the monochromator but is also available to users for experiments. As shown, the TSS has a single manipulator attached for sample insertion. Additionally, an off center, aft flange allows a detector to be inserted after the sample position at the TSS chamber center (not visible here).
End stations integrated for operation on the SXR instrument: (a) The resonant coherent imaging (RCI) end station features precision in vacuum sample manipulation and a soft x-ray sensitive CCD camera. It is optimized for coherent scattering experiments. (b) The surface science end station (SSE) features a sample manipulation system as well as an x-ray emission spectrometer and a hemispherical electron analyzer. It is intended for studying the chemical dynamics at surfaces and interfaces. (c) The resonant soft x-ray scattering (RSXS) end station features a cryostat with precision sample manipulation and a CCD camera that can read out one frame for each x-ray pulse.17 It is designed for soft x-ray diffraction to study correlated systems like high Tc superconductors. (d) The liquid jet end station (LJE) features a liquid jet sample injection system and a grating spectrometer. The LJE is used to study liquid phase chemistry.
The commissioning end station is a spherical vacuum vessel on an extruded aluminum frame. A long travel linear rail system moves the entire chamber system in the longitudinal beam direction. Welded bellows up and downstream of the chamber allow the vacuum system to accommodate for the long linear travel of the chamber in the longitudinal beam direction.
A block diagram of the controls system and connection interface for end station integration. Each end station uses a dedicated set of cables to connect end station devices to the interface panel. This enables simple access to the controllers and devices distributed over seven racks within hutch 2.
(a) The first image of a single-shot spectrum produced by a free electron laser at soft x-ray energies. The vertical axis is the horizontal extent of the beam with the energy dispersion in the horizontal axis. The horizontal axis for (b) is shared with (a). (b) Plots of the spectra are generated by projecting the center 2 mm of (a) thus averaging over the extent of the beam. Five characteristic single-shot spectra are normalized, offset and shown in blue and the average of 3000 spectra is shown in black.
Temporal overlap between the x-ray and optical pulses must be established for each experiment and monitored. Here, a simple and robust method for achieving sub 5 ps temporal overlap is illustrated. A rigid coaxial rf cable was terminated such that the center conductor comes to point which can be illuminated by both the optical and x-ray beam. The cable terminates in an SMA connector which is attached to a 25 GHz vacuum feedthrough (Times Microwave System P/N 59 130). The sufficient bandwidth is maintained through the transmission to take full advantage of the 13 GHz input bandwidth of the oscilloscope (LeCroy WAVEMASTER 813ZI).
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