Abstract:
A detector for radiation, particularly high energy electromagnetic radiation is provided. The detector includes a converting section including a cathode for converting the radiation incident on the converting section in electrons by the photoelectric effect. The detector further includes a gas electron multiplier for generating an electron avalanche from electrons which are generated by the converting section and enter the gas electron multiplier, the gas electron multiplier including a first electrode, a dielectric layer and a second electrode, the first electrode being disposed at a first side of the dielectric layer adjacent to the converting section and the second electrode being disposed at a second side of the dielectric layer opposite to the first side. The gas electron multiplier includes a number of holes filled with gas, the holes extending through the first electrode, the dielectric layer and the second electrode.
Abstract:
Detector for terahertz radiation with a micro-plasma cell (1) having a cavity (5) including a plasma in operation when applying a DC bias to the micro-plasma cell (1). Furthermore, the detector is provided with read-out electronics (20) connected to the micro-plasma cell (1). The read-out electronics measure changes of an electron density in the plasma in the micro-plasma cell (1) with respect to the DC bias provided electron density. The cavity (5) includes a gas composition near atmospheric pressure or higher, and the gas composition includes a Penning mixture.
Abstract:
A detector for radiation, particularly high energy electromagnetic radiation is provided. The detector includes a converting section including a cathode for converting the radiation incident on the converting section in electrons by the photoelectric effect. The detector further includes a gas electron multiplier for generating an electron avalanche from electrons which are generated by the converting section and enter the gas electron multiplier, the gas electron multiplier including a first electrode, a dielectric layer and a second electrode, the first electrode being disposed at a first side of the dielectric layer adjacent to the converting section and the second electrode being disposed at a second side of the dielectric layer opposite to the first side. The gas electron multiplier includes a number of holes filled with gas, the holes extending through the first electrode, the dielectric layer and the second electrode.
Abstract:
An ionization chamber radiation detector includes an outer shell, an inner well electrically connected to the outer shell to define an ionization chamber sensitive volume between them, and an ionization electrode that extends upwardly from a base into the space between the side walls of the well and shell. The shell and the walls of the well are grounded while the ionization electrode, which is electrically insulated from the shell, has a high voltage applied thereto. A guard electrode at the same voltage prevents electrical leakage. A sample positioner includes a thin walled guide tube which extends from a top cap down to a spacing disc. The spacing disc has an outer periphery which closely matches the interior of the well so that when the positioner is inserted into the wall the guide tube will be held at a desired position, preferably at the central axis of the well. A radiation source sample in a catheter is inserted through an opening in the top cap into the thin walled guide tube and down to a desired position within the tube, which precisely locates the source at a position which is preferably on the central axis of the detector. Close spacing between the source and the ionization chamber results in relatively high ionization current, allowing the radiation level to be measured based on the ionization current rather accumulated charge, and minimizing the effect of ambient background radiation.
Abstract:
The invention refers to a detector for radiation, particularly high energy electromagnetic radiation. The detector comprises a converting section including a cathode (3) for converting the radiation (P) incident on the converting section in electrons (E) by the photoelectric effect. The detector further includes a gas electron multiplier (4) for generating an electron avalanche from electrons (E) which are generated by the converting section and enter the gas electron multiplier (4), the gas electron multiplier (4) comprising a first electrode (5), a dielectric layer (6) and a second electrode (7), the first electrode (6) being disposed at a first side of the dielectric layer (6) adjacent to the converting section and the second electrode (7) being disposed at a second side of the dielectric layer (6) opposite to the first side. The gas electron multiplier (4) comprises a number of holes (9) filled with gas, said holes (9) extending through the first electrode (5), the dielectric layer (6) and the second electrode (7). Moreover, the detector includes a detector anode (8) adjacent to the second electrode (7) for detecting the electron avalanche. The detector according to the invention is characterized in that the detector anode (8) extends at each hole (9) of the gas electron multiplier (4) from the second electrode (7) over the hole (9) such that the hole (9) is covered at one side completely by the detector anode (8).
Abstract:
Detector for terahertz radiation with a micro-plasma cell (1) having a cavity (5) including a plasma in operation when applying a DC bias to the micro-plasma cell (1). Furthermore, the detector is provided with read-out electronics (20) connected to the micro-plasma cell (1). The read-out electronics measure changes of an electron density in the plasma in the micro-plasma cell (1) with respect to the DC bias provided electron density. The cavity (5) includes a gas composition near atmospheric pressure or higher, and the gas composition includes a Penning mixture.
Abstract:
The present invention relates to an ionization chamber. This comprises an inner wall and an outer wall which are mutually connected for enclosing a hollow space having ionized or ionizable gas therein. In or along the hollow space there are further arranged electrodes which can be connected to measuring equipment. The measuring equipment serves to determine a measure of the activity of a sample outside and in the proximity of the hollow space on the basis of a for instance ionizing reaction of the gas to the proximity of the sample. The ionization chamber defines a passage which is surrounded by the hollow space and opened at both ends thereof. With such a configuration the space for movements or transport of the sample out of the filling chamber can be minimized, because the ionization chamber in fact also forms the exit for the sample. The ionization chamber preferably further comprises sluice means.