U.S. Philips Corporation

Kristian Peschmann

Hans-Jurgen Hirsch

Hans-Georg Junginger

A radiation detection device comprising a housing which comprises an entrance window and in which at least one ionization chamber detector is arranged. The detector comprises a flat high-voltage electrode which is directed transversely transverse the entrance window and a flat collector electrode which is arranged to be at least substantially parallel to the high-voltage electrode. The end faces of these electrodes which face the entrance window are in electrical contact with a flat auxiliary electrode which extends parallel to the entrance window. As a result, a small direct current flows in a direction transverse to the other electrodes during operation, because the auxiliary electrode has a low electrical conductivity. Consequently, the electrical field in the ionization chamber detector is very homogeneous, with the result that the measuring speed can be optimized.

Radiation detection device

Xonics chambers can normally be used only with comparatively low electrode voltages in the Townsend-plateau region of the discharge where no charge carrier multiplication occurs. The sensitivity is then comparatively low. The sensitivity can be increased by increasing the electrode voltage, but this gives rise to a high electrode voltage for a reasonable charge carrier multiplication. According to the invention a gas is added whose ionization energy is smaller than the energy of the lowest metastable levels of the rare gas in the chamber. The charge carrier multiplication, and hence the sensitivity is thus improved without the electrode voltage being substantially increased. For example, when 0.2% by volume trimethylamine is added, an electrode voltage of 13 kV already suffices.

Electroradiographic device

An x-ray exposure device comprising a flat and plane rectangular chamber containing an ionizable gas and having walls provided with electrode structures which generate a potential distribution corresponding to that of two concentric spherical electrodes, an insulating foil on which charge carriers resulting from ionization of the gas by the x-radiation and displaceable in the longitudinal direction of the chamber being arranged therewithin.

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Aachen, Germany

Kristian Peschmann