Radiation detector with gas-permeable radiation window

Claim 1

In a detector for ionizing radiation of low energy, the detector including a wall enclosing a chamber adapted to contain a gas, two electrodes in said chamber, conductive means for connecting said electrodes to a source of electrical potential, a portion of said wall constituting a window more permeable to said radiation than the remainder of said wall, the improvement which comprises: a. a flat screen constituting said one portion of said wall, said screen consisting of a plurality of groups of phosphor bronze or austenitic stainless steel wires having a transverse dimension not substantially exceeding 100 microns, the members of each group extending in a common direction and transversely intersecting the members of another group to define with the same a multiplicity of minute openings uniformly distributed in said screen in such a manner that the screen presents a surface of approximately 1/3 open space and 2/3 metal to radiation directed against the screen at right angles to said surface; and b. feed means for feeding a gas to said chamber at a rate sufficient to maintain a pressure differential across said screen, the pressure in said chamber being higher than at the external side of said openings, 1. said openings constituting the sole substantial path for flow of said gas from said chamber.