  The small-angle neutron scattering instruments at the Oak Ridge National
Laboratory High Flux Isotope Reactor recently upgraded the area detectors from
the large, single volume crossed-wire detectors originally installed to
staggered arrays of linear position-sensitive detectors, based on the design
used on the EQ-SANS instrument at ORNL Spallation Neutron Source. The specific
geometry of the LPSD array requires that approaches to data reduction
traditionally employed be modified. Here, two methods for correcting the
geometric distortion produced by the LPSD array are presented and compared. The
first method applies a correction derived from a detector sensitivity
measurement performed using the same configuration as the samples are measured.
In the second method presented here, a solid angle correction derived for the
LPSDs is applied to data collected in any instrument configuration during the
data reduction process in conjunction with a detector sensitivity measurement
collected at a sufficiently long camera length where the geometric distortions
are negligible. Both methods produce consistent results and yield a maximum
deviation of corrected data from isotropic scattering samples of less than 0.05
for momentum transfers up to a maximum of 0.8 A-1. The results are broadly
applicable to any SANS instrument employing LPSD array detectors, which will be
increasingly common as instruments having higher incident flux are constructed
at various neutron scattering facilities around the world.
