The linearity performance of a two-dimensional, X-ray proportional chamber with 0.58 mm anode wire spacing

A method of construction of multiwire chambers has been developed which yields X-ray images with very small non-linearity, in particular that due to anode wire modulation. The technique requires an absorption region in the detector, with the anode and upper cathode wires, which are parallel to one another, in registration with each other. Studies show that the strength of the electric field in the drift region determines the degree of anode wire modulation and, under specific conditions, modulation is halved in period and significantly reduced in amplitude. New interpolating cathodes have been developed to read out position in the other axis, along the anode wire direction. Position resolution in both axes-between 100-150 /spl mu/m FWHM has been achieved. Two-dimensional images of small objects have been taken which show unprecedented linearity.<>