. in s - de t ] 4 A ug 2 00 6 Off line Parallax Correction for Neutral Particle Gas Detectors .

In a neutral particle gas detector, the parallax error resulting from the perpendicular projection on the detection plane or wire of the radial particle trajectories emanating from a point like source (such as a scattering sample) can significantly spoil the apparent angular resolution of the detector. However, as we will show, the information is not lost. We propose an off line data treatment to restore as much as possible the original scattering information in the case of a one-dimensional parallax effect. The reversibility of parallax follows from the algebraic structure of this effect, which is different from the resolution loss which is essentially irreversible. The interplay between finite resolution and parallax complicates the issue, but this can be resolved.