45-meter VSANS Instrument @ Guide NG-3 CHRNS-logo

Design Features:

The VSANS instrument on guide NG-3 is 45 meters in total length. A high resolution (0.2 mm fwhm) 2D detector along with a longer flight path (45 m) allows a factor of four smaller q to be measured, qmin = 0.002 nm-1, compared to the 30 m instruments. To enhance count rate at the smaller q-range, larger samples or relaxed resolution is employed. Converging beam collimation allows utilization of larger samples with a gain of a factor of 200 over standard pinhole collimation. Relaxed resolution using slit collimation with small samples produces a gain of 25,000 over pinhole collimation. The instrument has three separate detectors that can be placed independently at different distances from the sample allowing the full q-range, 0.002 nm-1 ≤ q ≤ 10 nm-1 to be measured in one setting. The incident wavelength, and wavelength resolution, are controlled over a wide range with either a standard resolution mechanical velocity selector (Δλ/λ = 12%), high resolution graphite monochromator (Δλ/λ = 1%), or low resolution filtered beam covering 0.4 nm ≤ λ ≤ 0.8 nm with Be filter and guide deflector. The instrument has a large 2 m sample area allowing larger ancillary sample environments to be used. Full beam polarization using a 3He analyzer is also available. All instrument configurations are controlled by computer.

VSANS NG3 Guide Schematic