| 摘要 |
A detector for detection of ionizing radiation, an apparatus for use in planar beam radiography, comprising such a detector, and a method for detecting ionizing radiation. The detector includes a chamber filled with an ionizable medium, at least one first electrode arrangement provided in said chamber where said at least one first electrode arrangement includes an electron avalanche amplification unit, said electron avalanche amplification unit including at least one avalanche cathode and at least one avalanche anode between which a voltage is to be applied for creation of an electric field for avalanche amplification, and at least one arrangement of read-out elements for detection of electron avalanches, wherein said at least one avalanche cathode has at least one hole or opening, wherein an area of said at least one hole or opening in the avalanche cathode is bigger than an area of at least one associated anode as seen from above and where said at least one anode is centered with respect to said at least one hole or opening in the avalanche cathode. A radiation entrance is provided so that radiation enters the conversion volume between the first and second electrode arrangements. In order to achieve well-defined avalanches, the electron avalanche amplification unit includes avalanche regions. The detector, apparatus and method is advantageous since it prevents the formation of harmful sparks. |
