Specifications

CXI Scientific Capabilities

Scientific Applications
  • Coherent X-ray imaging on single sub-micron particles
  • Serial Femtosecond Crystallography
  • High Fluence X-ray interactions with matter
  • Time-resolved imaging and scattering with hard X-rays
  • Matter in Extreme Conditions
  • Atomic, Molecular and Optical Science
Techniques and Scattering Geometry
  • Forward scattering on fixed-mounted samples, free-standing injected particles and in liquid jets
  • Back-scattering
  • Ion Time-of-flight
  • Small Angle X-ray Scattering
  • Wide Angle X-ray Scattering
  • X-ray Emmission Spectroscopy

Source Parameters

Photon Energy 5-10 keV for the 1st harmonic*
Up to 25 keV for 2nd and 3rd harmonic
Source Size 60 x 60 µm2 (H x V) FWHM @ 8.3 keV
78 x 78 µm2 (H x V) FWHM @ 2 keV
Source Divergence 2 x 2 µrad2 (H x V) FWHM @ 8.3 keV
~7 x 7 µrad2 (H x V) FWHM @ 2 keV
Repetition Rate 120 , 60, 30, 10 Hz, Single shot mode
Pulse Duration 40-300 fs (high charge mode)
<10 fs (low charge mode)
Pulse Energy 1-3 mJ  (high charge mode)
~ 0.2 mJ  (low charge mode)
Photons per Pulse ~1 x 1012 (high charge mode @ 8.3 keV)
~1 x 1011 (low charge mode @ 8.3 keV)

* Energies below 5 keV are in principle usable but the beam size at the end station is large leading to poor focusing performance and reduced flux. Also, the detector efficiency drops rapidly below 5 keV.

Photon Beam Properties

Focusing Capability KB1 mirrors (1.3 µm focus)
KB01 mirrors (~100 nm focus)
Beryllium Lenses in XRT (10 µm focus)
Beryllium Lenses in Hutch 5 (~1 µm focus)
Beam Size at Sample (8 keV)

(Calculated for perfect optics)

1.3 x 1.3 µm2 FWHM with 1 micron KB pair (KB1)
90 x 150 nm2 FWHM (V x H) with 100 nm KB pair (KB01)
10 x 10 µm2 FWHM with XRT Be Lenses
~1 x 1 µm2 FWHM with Hutch 5 Be Lenses
750 x 750 µm2 FWHM unfocused beam
Beam Divergence

(Calculated for perfect optics)

0.12 x 0.12 mrad2 FWHM with 1 micron KB pair (KB1)
2 x 1 mrad2 FWHM (V x H) with 100 nm KB pair (KB01)
170x 170 µrad2 FWHM with XRT Be Lenses
~0.3 x 0.3 mrad2 FWHM with Hutch 5 Be Lenses
2 x 2 µrad2 FWHM unfocused beam
Beam Size at Sample (4 keV) 4 x 4 µm2 FWHM with 1st KB pair (KB1)
300 x 450 nm2 FWHM (V x H) with 2nd KB pair (KB01)
Unusable with XRT Be Lenses
Unusable with Hutch 5 Be Lenses
3000 x 3000 µm2 FWHM unfocused beam
Energy Range 2-10 keV (1st harmonic)
10-25  keV (2nd and 3rd harmonic)
Energy Resolution ΔE/E ~0.2% (bandwidth of the LCLS beam)
No monochromator currently

Sample Environment and Detector

Sample Environment
  • High vacuum: 10-7 Torr
  • Fixed sample on grids at room temperature
  • Possible to operate at atmospheric pressure with limitations on use of some CXI equipment. Also, large increase in air scatter might prevent operation of the detector in the forward direction.
Particle Injector
  • Free-standing nanoparticles delivered to the beam using an aerodynamic lens particle injector
  • User-provided injectors can be incorporated into the system
  • Liquid jet to delivered samples in hydrated conditions
Detectors
  • 2-Dimensional pixel array detector, 110 x 110 µm2 pixel size
  • Single photon sensitivity, 103 dynamic range at 8.3 keV
  • Cornell-SLAC Pixel Array Detector (CSPAD) 1516 x 1516 pixels
  • 120 Hz operation
  • Two full CSPAD detectors available for wide angle and small angle measurements
  • CSPAD 140K (380 x 380 pixels) small version of CSPAD available for miscellaneous use

Short Pulse UV Laser

In order to improve the overall time resolution of ultrafast X-ray scattering measurements performed at the CXI instrument, the UV capabilities of the CXI laser are being upgraded to produce shorter pulses. This is being done in 2 stages: first the 3rd and 4th harmonics (267 nm and 200 nm, respectively) of the Ti:sapphire laser are being improved by increasing the spectral bandwidth and minimizing the dispersion of the travelling pulses. In a second phase of upgrade, an OPA and a variety of sum frequency generation schemes will be used to generate tunable pulses in the 185-265 nm range.

Phase 1: Improving the time resolution of the 3rd and 4th harmonics

  Current Pulse Width
(FWHM)
Expected Performance
(FWHM)
267 nm (3ω) ~80 fs ~30 fs
200 nm (4ω) ~120 fs ~35 fs

Phase 2: Generating tunable deep UV pulses

  Current Capability Target Capability
185-265 nm - 30-40 fs

Completion of phase 1 is expected by the start of user operations in run 18 (March 2020), and completion of phase 2 is expected during the summer/fall of 2020. All expected performance values are based off a best effort basis.