qRIXS Capabilities

qRIXS Capabilities for Run 27

qRIXS is a dedicated instrument designed to investigate correlated-electron condensed matter systems using a broad range of time-resolved spectroscopy techniques. It will be available for general user proposals in the Run 26 call, operating at the anticipated 120 Hz repetition rate.

The qRIXS instrument supports a variety of experimental modalities, including time-resolved resonant inelastic X-ray scattering (tr-RIXS), transient X-ray absorption, diffraction, and reflectivity. Optical excitation from the terahertz (THz) to ultraviolet (UV) regime is enabled by the Carbide laser system, operating at its fundamental wavelength of 1030 nm.

In general, due to the low repetition rate of LCLS-I, time-resolved RIXS experiments will not be offered unless an exceptionally strong scientific justification is provided.

The following capabilities will be supported:

• Sample positioning on an in-vacuum diffractometer, 6 degrees of freedom, sphere of confusion <50 microns
• At the moment only bulk samples and thin films on substrates will be considered
• A load-lock chamber  
• Sample cooling with base temperature ~ 25 K
• Diagnostic paddle for calibration targets, spatio-temporal overlap, etc.
• Laser in- and out- coupling (in co-linear configuration)
• Detectors optimized for x-ray absorption and diffraction
• Arrival time monitor located ~1.5 m from the interaction point

qRIXS operations in Run 27 will be focused on standard user experiments. In preparation for these efforts the following tables summarize the expected x-ray and laser capabilities for the Cu accelerator and CARBIDE laser system. 

Performance Parameters for Run 27

The following detectors will be provided to the users:

• Avalanche PhotoDiodes (APD) and Large area photodiodes.  The APDs are single-photon sensitive fast detectors suitable for X-ray Absorption Spectroscopy (XAS) in Total Fluorescence Yield (TFY) mode, and for X-ray Diffraction.  These detectors will be mounted on an in-vacuum rotatable stage (2-theta arm) and can be placed in the horizontal scattering plane.
• qRIXS spectrometer (Archon).
  • The archon CCD pixel dimensions are 1200x4224 px. Dispersion is along the long axis.
  • Modes available:
    • 2D mode which is binned by 2px along the short axis, i.e. 600 x 4224 px at a frame rate of 1 Hz.
    • 1D mode which is full vertical binning along the short axis, i.e. 1x4224 at a frame rate of 102 Hz.
• Depending on timely delivery, an in-vacuum 2D detector will be offered as well, with the following characteristics:
  • 512 X 512 pixels
  • 50 um pixel size
  • 5 kHz full frame readout
    This detector will also be mounted on the 2-theta arm

Users are encouraged to contact Apurva Mehta, mehta@slac.stanford.edu and Georgi Dakovski, dakovski@slac.stanford.edu for more information.