Radiant energy – Invisible radiant energy responsive electric signalling – Including a radiant energy responsive gas discharge device
Patent
1998-07-16
2000-10-17
Hannaher, Constantine
Radiant energy
Invisible radiant energy responsive electric signalling
Including a radiant energy responsive gas discharge device
250374, G01T 1185
Patent
active
061335754
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an ionizing particle detector.
It is applicable particularly in particle physics, and in medicine and biology, in the fields of .beta. ray imagery and X ray imagery.
2. State of the Prior Art
Document (1) G. CHARPAK et al., "Gaseous detectors with parallel electrodes and anode mesh planes", Nuclear Instruments and Methods in Physics Research A274 (1989), p. 275 to 290, describes an ionizing particle detector comprising a cathode consisting of a grid formed of woven wires with a mesh size of the order of 600 .mu.m.
Consequently, the cathode and anode of the detector must be spaced by several millimeters to avoid an excessive fluctuation of the gain in the amplification gap between the anode and the cathode.
The large distance between these two elements limits the spatial resolution and the count rate of this detector.
With this distance between the cathode and the anode in this known detector, the time necessary for collection at the cathode of ions generated by an avalanche process in the amplification gap is relatively long.
Furthermore, this relatively long collection time means that electrical signals are collected at the detector anode with a relatively long rise time, causing stacking problems in electronic processing means for these signals.
DESCRIPTION OF THE INVENTION
This invention relates to an ionizing particle detector with a spatial resolution significantly higher than the known detector mentioned above, and capable of detecting ionizing particle flows significantly higher than this known detector.
More precisely, the purpose of this invention is an ionizing particle detector, this detector comprising: chamber and kept parallel with each other, the first and second electrodes delimiting a conversion gap in which particles generate electrons, the second and third electrodes delimiting an amplification gap in which these electrons are multiplied by an avalanche process, the second electrode being perforated by holes and forming a cathode, the third electrode forming an anode and comprising a set of elementary anodes electrically insulated from each other, and potential, the cathode to a second potential higher than the first potential, and elementary anodes to a third potential higher than the second potential, these polarization means thus being capable of creating electric fields in the conversion and amplification gaps respectively, .mu.m and the ratio R of the intensity of the electric field created in the amplification gap to the intensity of the electric field created in the conversion gap exceeding 10 and wherein the detector further comprises means for amplifying and processing electric signals from the elementary anodes when the electrons are multiplied in the amplification gap.
As we will see better later, the use of a short distance of less than 500 .mu.m between the cathode and anode of the detector according to the invention makes it possible to have this detector elementary anodes with a size approximately equal to or less than this distance, so that a very high spatial resolution can be achieved.
Furthermore, the ratio between the intensities of the electric fields mentioned previously is significantly higher in this invention than it is in the known detector mentioned above.
As we will see better later, this enables detection of significantly higher particle flows than is possible using this known detector.
Preferably, the distance D between the cathode and the anode of the detector according to the invention does not exceed 200 .mu.m.
The spatial resolution that can be achieved with this detector is higher when this distance D is low.
Also preferably, the ratio R between the electric field intensities is equal to at least 50.
As we will see better later, this means that very high ionizing particle flows can be detected.
According to one preferred embodiment of the detector according to the invention, the thickness E of the cathode is less than D/10.
This gives good uniformity of the gain in the amplification gap of the
REFERENCES:
patent: 5223717 (1993-06-01), Charpak
patent: 5308987 (1994-05-01), Wuest et al.
patent: 5596201 (1997-01-01), Charpak
Nuclear Instruments & Methods in Physics Research, Section--A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 274, No. 1-2, Jan. 1, 1989, Amsterdam NL, pp. 275-290, XP000121570 G. Charpak et al.: "Gaseous detectors with parallel electrodes and anode mesh planes," cite dans la demande voir p. 280 -p. 281; figure 10.
Charpak Georges
Giomataris Ioannis
Rebourgeard Philippe
Robert Jean-Pierre
Biospace Instruments
Hannaher Constantine
Israel Andrew
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