Advanced Photon Source

An Office of Science National User Facility

Techniques and Facilities

Originally constructed and operated as "MHATT-CAT" by a consortium from University of Michigan, Howard University, and Bell Labs-Lucent Technologies, 7ID is now an APS beamline specializing in time-resolved x-ray scattering and spectroscopy.  The time structure of the x-ray beam is used to achieve temporal resolution of 90 ps or less, depending on the fill pattern of the APS storage ring.  Three experimental hutches allow for a wide variety of experimental setups.A climate-controlled laser lab houses a fs laser while high rep-rate lasers reside in an experimental hutch.

Information on the various hutches:

  • 7ID-B A white-beam hutch for imaging fuel sprays and high-pressure liquids
  • 7ID-C The laser-pump x-ray diffraction probe station at APS beamline 7ID
  • 7ID-D Time-resolved x-ray spectroscopy and scattering of atoms and molecules

The 7ID beamline has been described in a proceedings paper from the International Synchrotron Radiation Instrumentation 2009 conference: Time-Resolved Research at the Advanced Photon Source Beamline 7-ID, Eric M. Dufresne, Bernhard Adams, Dohn A. Arms, Matthieu Chollet, Eric C. Landahl, Yuelin Li, Donald A. Walko, and Jin Wang, AIP Conference Proceedings 1234, 181-184 (2010), DOI: http://dx.doi.org/10.1063/1.3463168

X-ray Characteristics
  • 7ID monochromatorEnergy range (nominal): 6-24 keV
  • Flux: 3x1012 photons/s at 10 keV
  • Bandpass: 5.4x10-5
  • X-ray bunch length (24-bunch mode): 90 ps

The x-ray source for 7ID is an APS Undulator A, with a period of 3.3 cm and length of 2.4 m.  The 7ID-A enclosure contains a double-crystal, water-cooled diamond (111) monochromator for delivering x rays to the experimental stations.The 7ID-B hutch can also accept white-beam radiation.

X-ray spectrum measured in 7ID-C

This figure displays the measured x-ray spectrum in the 7ID-C hutch.White-beam slits were set to 0.5 mm horizontal by 0.55 mm vertical; the insertion device and diamond (111) monochromator were optimized before each data point was collected.  The x-ray flux thru a 1 mm x 1 mm slit was measured by an air-filled ion chamber 52 m from the source.  These are not the settings used in all experimental configurations; delivered x-ray flux depends on a number of factors.

Laser Characteristics

Spectrum of pulse energies for the various laser excitation sources available at 7ID:Laser sources available at 7ID

  • Red circles: Ti:sapphire amplifier and harmonics
  • Red square: Ti:sapphire oscillator
  • Black lines: Ti:sapphire-pumped OPA
  • Blue triangle: Ti:sapphire-derived THz excitation
  • Green symbols: Duetto MOPA at various repetition rates and harmonics

 

 

 

Femtosecond Laser7ID fs laser

  • Located in separate, climate-controlled laser lab
  • Transported to 7ID-C and D via in-vacuum overhead transport
  • Oscillator
    • Coherent Micra Ti:Sapphire 300 mW, 20 fs
    • 88 MHz repetition rate
    • Synchronized to accelerator RF within 250 fs rms
  • Amplifier
    • 800 nm Ti:Sapphire CPA regen (Coherent Legend)
    • 2.5 W average power compressed to 50 fs
    • 2.5 mJ/pulse at 1 kHz
    • Conversion to 400 nm at 15% efficiency
  • Optical Parametric Amplifier (OPA)
    • 100-fs pulses from 200 nm to 20 µm at 1 kHz, with >10 µJ/pulse
  • Intense THz source
    • Peak field ~100 kV/cm, pulse duration 500 fs
    • Bandwidth 0.1-2 THz with central wavelength 0.8 THz

 

High Rep-Rate Laser7ID high rep rate laser

  • Located in 7ID-D experimental hutch
  • Transportable to 7ID-C via overhead transport
  • Time-Bandwidth Duetto System
    • 10 ps and 130 ps pulse durations
    • Repetition rate variable from 54 kHz to 6.52 MHz
    • 10 W power at 1064 nm and 54 kHz (185 µJ/pulse)
    • Easily converts to higher harmonics 532, 355, and 266 nm
  • Most efficient use of the high flux/high rep rate of the APS