Radiant energy – Invisible radiant energy responsive electric signalling – Including a radiant energy responsive gas discharge device
Reexamination Certificate
2002-02-22
2004-11-23
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Including a radiant energy responsive gas discharge device
Reexamination Certificate
active
06822239
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a particle beam image detector employing gas amplification attained by pixel-type electrodes.
BACKGROUND ART
The present inventors have previously developed an MSGC (Micro Strip Gas Chamber), which is a gas amplification-type particle beam image detector which provides high position resolution and high incident particle tolerance and which has strip-type electrodes. Characteristic features of this detector include a very short dead time for a gas amplifier and high position resolution, and the detector has attracted keen interest for its potential use as a detector for particle beams of high brightness. Presently, tests employing X-rays have confirmed that the detector is free of malfunction under a brightness of 10
7
counts/mm
2
·second or more.
FIG. 1
is an exploded perspective view of a conventional MSGC.
The MSGC imaging device shown in
FIG. 1
has an effective area of 10 cm×10 cm. Reference numeral
1
denotes a substrate made of a polyimide thin film. Reference numeral
2
denotes an anode strip formed on substrate
1
, and reference numeral
3
denotes a strip-shaped cathode electrode. Anode strips
2
and strip-shaped cathode electrodes
3
are juxtaposed alternately.
Reference numeral
4
denotes a base substrate made of ceramic, and reference
5
denotes a back-side electrode formed on the base substrate
4
and placed under the substrate
1
.
At a distance approximately D
1
above the thus-constructed element is located a drift plate
6
to thereby define a chamber for allowing passage of gas therethrough;
e.g., a gas containing argon and ethane (see, for example, Japanese patent Application Laid-Open (kokai) No. 10-300856).
DISCLOSURE OF THE INVENTION
One critical problem associated with the above-described MSGC is breakage of the electrodes resulting from discharge between the electrodes. In the case of the conventional MSGC, a voltage is applied between electrodes having a clearance of 50 &mgr;m or less. Therefore, when a high voltage is applied in the hope of increasing the gas amplification factor, a large current flows between the electrodes. As a result, it frequently occurs that heat generated from discharge destroys the electrode strips, or fragments of the broken electrode strips are deposited onto the surface insulating layer, resulting in malfunction of the device.
Moreover, since signals generated in the back-side electrodes
5
, which are a two-dimensional read out, have a magnitude about 20% that of the signals generated by the anodes located on the surface side, an expensive amplifier must be employed in a circuit for attaining successful read-out of such weak signals, or alternatively, the amplification factor attained as gas amplification must be further improved.
In view of the foregoing, an object of the present invention is to provide a particle beam image detector employing gas amplification attained by pixel-type electrodes, the detector having high sensitivity and electrodes of improved reliability.
In order to achieve the above object, the present invention provides a particle beam image detector employing gas amplification attained by pixel-type electrodes, comprising anode strips formed on one surface of a substrate, columnar anode electrodes which are supported on the anode strips and penetrate the double-sided substrate so as to extend into apertures in the strip-shaped cathode electrodes. Each of the anode strips may have a width of about 200 to 400 &mgr;m.
The anode strips are provided at intervals of about 400 &mgr;m, the strip-shaped cathode electrodes each have apertures spaced a predetermined distance, the diameter of the aperture being about 200 to 300 &mgr;m, and each of the columnar anode electrodes has a diameter of about 40 to 60 &mgr;m and a height of about 50 to 150 &mgr;m.
REFERENCES:
patent: 4280075 (1981-07-01), Comby et al.
patent: 5742061 (1998-04-01), Lemonnier et al.
patent: 9-508750 (1997-09-01), None
patent: 10-300856 (1998-11-01), None
Ochi Atsuhiko
Tanimori Toru
Hannaher Constantine
Japan Science and Technology Corporation
Lorusso, Loud & Kelly
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