General-Purpose Small-Angle Neutron Scattering Diffractometer


Mission Statement

It's the little things that matter.

Instrument Description

The properties and performance of hard and soft matter systems is often intimately linked to the internal microstructure. Small-angle neutron scattering (SANS) is a uniquely powerful tool for probing structural information on length scales ranging from 0.5-200nm. Among the features that make it so useful are the facts that neutrons are highly penetrating, low-energy, magnetic, and sensitive to the nuclei of atoms. These properties make it a complementary probe to x-ray scattering and microscopy techniques and make location of light elements, distinguishing between atoms nearby on the periodic table, isotopic labeling, and the separation of magnetic and nuclear scattering contributions possible. 

The General-Purpose Small-Angle Neutron Scattering Diffractometer (GP-SANS) CG-2 instrument is optimized for providing information about structure and interactions in materials in the range of 0.5–200 nm. It has a cold neutron flux on sample and capabilities comparable to those of the best SANS instruments worldwide, including a wide range of neutron wavelengths (4–20 Å), a resolution Δλ ⁄ λ 9-25%, and a 1 m2 area detector with 8 × 4 mm2 pixel resolution with a maximum counting capability of up to 2 mHz. The sample-to-detector distance can be varied from 1–19 m, and the detector can be offset horizontally by up to 40 cm, allowing a total accessible Q range from <0.001 to 1.3 Å-1. The 2 m sample environment area will accommodate large, special-purpose sample environments such as cryomagnets, furnaces, mechanical load frames, and shear cells.



  • Soft condensed matter:
    Molecular self-assembly and interactions in complex fluids; intermediate order in glassy systems, polymer solutions, gels and blends, colloids, micelles, and microemulsions
  • Hard condensed matter:
    Phase separation, grain growth, and orientation in metallurgical alloys, nanocomposites, advanced ceramics, and porous catalytic and adsorbent materials
  • Magnetic systems:
    Flux lattices in superconductors, ferrofluids, magnetic spin textures, and the relationship between structural and magnetic domains


Beam Spectrum Cold
Monochromators Velocity selector
Incident wavelength 4 < λ < 20 Å
Resolution Range Δλ ⁄ λ= 9 – 25%
Collimation Eight removable guide sections, each 4 x 4 cm2 and 2 m long; 2 m open area at sample stage to mount automatic changers, furnaces, magnets, cryostats, pressure cells, etc.
Q range (Å-1)
Collimation 6 m, SDD 1 m
Collimation 6 m, SDD 6 m 
Collimation 17 m, SDD 19 m

4.75 Å 0.05-1 Å-1
4.75 Å 0.008-0.202 Å-1
12 Å 0.001-0.025 Å-1 
Sample detector distances 1 - 19 m
Detector 1m wide array of 192 1m long He3 LPSDs
Max counting rate 2 kHz/pixel, 2 Mhz over the detector