Extended Q-Range Small-Angle Neutron Scattering Diffractometer (EQ-SANS)
The EQ-SANS Diffractometer is designed to study non-crystalline, nano-sized materials in solid, liquid, or gas forms such as polymers, micelles, proteins, and other large biological molecular complexes in solution. It is designed to have high neutron flux, high wavelength resolution (precision), and wide Q-coverage.
The instrument is located on beam line 6, viewing the top-downstream, coupled supercritical hydrogen moderator. It has a curved multichannel beam bender to avoid the direct line of sight of the moderator, which cleans out the background from the prompt neutron pulse quite effectively. The cutoff wavelength of the optics is ~1.5 Å. Above this minimum wavelength, the three bandwidth choppers on the EQ-SANS define a clean wavelength band of ~3.5 Å at 60 Hz. The choppers also enable a 30 Hz frame-skipping operation, which allows the instrument to have a bandwidth of ~10 Å. At present, the instrument has a 1 × 1 m low-angle detector, which will be expanded to 1 × 1.4 m. The low-angle detector can travel along the beam inside the scattering tank, giving a variable sample to detector distances of ~1.2 to 10 m.
Absolute flux measurement at the sample position is ongoing. Preliminary data collected on the same sample indicate that the flux of EQ-SANS is very competitive when compared with some of the best SANS instruments located on steady-state sources.
The available sample environment is a 45-cell automated sample changer than can be controlled between 5 and 80°C. Other sample environment equipments (furnaces, magnets, cryostats, etc.) will be adapted to the instrument in the near future.
| Instrument Specifications | |
|---|---|
| Sample to source distance | 14 m |
| Sample to detector distance | 1.2 – 10 m |
| Bandwidth | ~3.5 Å at 60 Hz |
| Moderator | Coupled supercritical hydrogen |
| Integrated flux on sample | ~107 – 108 n/cm2/s |
| Q range | 0.004 Å-1 < Q < 1.5 Å-1 |
