US2605435A - Construction of geiger-muller tube - Google Patents

Description

y 29, 1952 s. KRASNOW El'AL 2,605,435

CONSTRUCTION OF GEIGER-MULLER TUBE I Original Filed Oct. 1, 1941 A i Z 2 16 15 J0 El, '9 11 J2 17 14 6 Sammy kegs/vow. MEYER fasfpz/ 7Z5 7.

Patented July 29, 1952 CONSTRUCTION or GEIGER-MU'LLER I Shelley Krasnow', Fairfax Couiitm. Va.,. and Meyer Joseph. Test, Kansas City, Mo., assignors to Schlumbe -ger Well Surveying Corporation, Houston, Tex, a corporation ofDelawar'e Original" application October 1, 1941, Serial No. 413,240. Divided and this application May 19",. 1948, Serial N0. 27,856

ments of radioactive and other nuclear raysv generally and of. particular advantage in the measurement of radioactive and nuclear rays in,

boreholes.

It is an object of the invention to provide a Geiger-Muller counter tube of high strength, not subject to theusual fragile character of tubes heretofore used.

It is a furtherobject of the invention to providea Geiger-Muller counter tube which is demountableand which is. capable of being readily repaired or modified.

It is a further object of the invention to provide a Geiger-Muller counter tube relatively free of substances which cause spurious effects, thereby providing atube with a lowered background count.

It is a further object of the invention to provide' a Geiger-Muller counter tube having such an electrical structure that spurious effects are reduced substantially, thereby yielding a tube of lower background and higher sensitivity.

It is a further object of the invention to provide a Geiger-Muller counter tube which may be constructed of readily available and relatively in expensive materials.

' It is a'further object of the invention to provide a sealing member for the closure of a Geiger-Muller countertube to secure effective, strong and economical construction while improving the operation of such tube.

Theseand other objects and" advantages of the invention will appear from the description given in the specification taken in conjunction with the drawings in which:

Figure 1 shows a longitudinal cross-sectional view of the Geiger-Muller counter tube.

Figure 2 shows an enlarged view of the insulator and seal, employed in the assemblage in Figure 1 showing the method of assembly.

Figure 1 shows a Geiger-Muller counter tube employing an improved construction, which hasadvantages for use in measuringradio-activity in boreholes. This consists of a metallic tube I, which may be provided with threaded ends 2. Fastened to these threaded ends are internally threaded collars 3, into which are screwed externally threaded inserts 4 and 5. Both inserts have cap screws or the equivalent, 6, threaded therein and serving to bear against heads 1 and 8 respectively. Head 1 has ablind cavity 9 into which isfitted an insulating tube I 0, held by some means such as a packing of lead it. A

metallic wire I2, extends from tube [0 andis' firmly connected thereto. An opening 13 in head 1 has a tube, preferably a thin copper tube, fastened therein as by soldering. This passes. through an. opening in head 5 and may be connected to a suitable. apparatus for pumping and filling the'tube. A closure in the form of a well constructed needle valve M, may be. provided at the terminal portion of. the tube 15. Alternatively, the tube may be pinched closed after evacuation or filling with a pair of blunt cutting nippers, or soldered shut. Head 8' has a neck portion [6 through which is provided an opening l1. Soldered into this opening is a thin metallic tube [8, which may be of copper, and which extends beyond the exterior of the head 8. Atthe terminal portion [9 of this tube is fastened an insulating tube which may bear glass or quartz tube which is sealed to the copper by means of either soldering by standard methods, or by the use of a so called Housekeeper seal. The insulating tube 20 extends inwardly forming a pro--.'

jecting portion2 I. This serves as a shield which prevents spurious effects in the apparatus. 'The wire l2 passes centrally through tube 20 and, a gas-tight seal is formed at 22. The wire prefer: ably has, at, its end a metal of the type f 1 51 sten 22 where the sealis to beformed, j I

The Geiger-Muller tube itself, in many cases, will be found to be sensitive to temperature. and to require difierentoperating voltages at differ: ent temperatures. The Geiger Miiller tubejmay have an outer wall I made double, with an annular cylindrical, space. which is evacuated. Thus, the tube will be thermally insulated against external temperature, change.

It is noted that the, Geiger-Muller tube is made almost entirely of metal. construction make for a more rugged unit, capable of withstanding shocks metwith. in boreholes, but it, avoids another defect. Glass, as ordinarily utilized. in making Geiger-Muller counter tubes, is intrinsically radioactive, possibly due to potassium. contained therein. This will cause the counter to give responses even in the. absence of other radioactive materials. Further, glass or other insulating material will accumulate static charges which will later discharge, giving the same effect, in the circuit as a pulse due. to radio-activity. The insulating material in the tube shown herein has been reduced to a mini; mum, and it has also been found desirable to use fused quartz instead of glass. Not, only is clean natural quartz intrinsically: quite free of radioactive materials. but the temperature. neces- Not only does this,

sary to fuse the quartz is suiiicient to volatilize practically all radioactive materials. Fused quartz is therefore normally purified and will be found highly desirable for radioactive measuring equipment. It is fact preferable to make counter tubes entirely of fused quartz, than to make them of glass where the orthodox methods of construction are to be used.

While the specific embodiment has been drawn chiefly to a Geiger-Muller tube, it will be understood that the construction of the tube and the mode of its use may be applied to an ionization chamber apparatus.

This is a division of application Serial No. 413,240, filed October 1, 1941, and now abandoned.

The scope of the invention is indicated by the appended claims.

We claim:

1. In a Geiger-Muller counter tube, a principal conducting tubular portion and metallic end closures, and a plurality of clamping means retaining the said closures releasably in gastight relationship to the principal tubular portion and in electrical and firm mechanical contact therewith, one of the said metallic closures presenting a full conducting surface at the exterior of the Geiger-Muller tube, but having fastened therein an insulator to retain the central wire of the tube in insulated relation thereto, the other of the said closures having an insulator passing completely therethrough serving to locate the central wire within the tube and to establish electrical connection between the said central Wire and points exterior of the said tube.

2. In a Geiger-Muller counter tube, a conducting head member, an annular member fastened in gastight relationship to the said conducting member, insulating material fastened in gastight relationship to the said annular member and a conducting element passing completely through the insulating member in gastight relationship thereto, to conduct current from the interior of the assembly to the exterior thereof.

3. In a Geiger-Miller tube, a conducting rod, insulator and metallic sleeve, the said rod, insulator and. sleeve being mounted coaxially of one another and in gastight relationship with one another but with an annular space between said rod and insulator, the said sleeve having an outwardly extending flange adapted to be fastened in gastight relationship to one of the ends of a Geiger-Muller counter tube.

4. In a demountable Geiger-Muller tube, a central tubular portion, a metallic end member adapted to be maintained in gastight relationship to one end of said tubular portion, and clamping means mounted on said one end of the tubular portion to clamp the said end member positively but releasably in gastight relationship to the said tubular portion.

5. A closure for one end of a Geiger-Muller tube adapted to permit the conducting of current from the interior of the tube to the exterior thereof while maintaining the assemblage in gastight condition, comprising a central conducting member, an intermediate insulating member and an external conducting member, the internal and external conducting members and insulating member being rigidly attached to each other in gastight relationship, with an annular space between said internal conducting member and the insulating member, the'insulating member projecting beyond the external conducting member at that end which faces inwardly into the operative volume of the Geiger-Muller tube, whereby 4 the central conducting member is protected against discharge between itself and said external conducting member.

6. In the construction of a Geiger-Muller tube, an annular metallic member adapted to be attached to the head end of a Geiger-Muller tube and to form one boundary of the active volume thereof, an insulating member of glass fastened to the said metallic member by a glass-metal seal, so that the two are in mechanically rigid and gastight relationship to one another, a central conducting member fastened in gastight relationship and mechanically rigid relationship to said glass member, with an annular space between said central conducting member and said insulating member, and forming an additional glass-metal seal, the glass member extending beyond the annular member at both ends thereof preventing gas discharge phenomena except at desired points within the Geiger-Muller tube.

7. A Geiger-Muller counter tube in accordance with claim 1 in which the insulators are made of quartz.

8. In an ionization chamber, a conducting en- 1 closure, the said enclosure constituting a gastight container, an inner electrode adapted to be maintained at a high voltage relative to the said enclosure and a gas contained within the said enclosure, the said inner electrode being supported at at least two points, so as to be maintained in spaced relationship with and insulated from the said enclosure, an insulating member carrying a conductor completely through the enclosure, so as to enable connection with the said central electrode, the said member having an insulating portion extending part way into said enclosure and spaced from said central electrode by a substantially annular space.

9. In a Geiger-Muller tube containing a gas, a hollow conducting outer electrode forming an outer gas-containing element of said tube, a conducting closure at the end of said electrode, clamping means retaining said closure in electrical conducting and firm mechanical and gastight relation with the end of said electrode, said closure having an inner conducting surface forming a boundary of the gas containing volume of said tube, an inner electrode within said hollow electrode and spaced therefrom, an electrical lead attached to said inner electrode and passing through said closure, an insulator in said closure insulating said electrode and lead from the conducting closure, said insulator projecting inwardly beyond said inner surface and into the electric field established when a potential difference exists between said inner and outer electrodes.

10. In a demountable Geiger-Muller tube, a central tubular member having an end portion, a closure portion, both of said portions having contact surfaces, and clamping means mounted on said end portion of the tubular member, the end and closure portions being assembled together at their contact surfaces and held in assembled gastight relationship by the clamping means, at least one of said portions being provided with a soft metallic part, the compression thereof at a contact surface by said clamping means effecting a gastight seal.

11. A closure and insulating member for a Geiger-Muller tube comprising a conducting member with a flattened annular surface to engage an end of the tubular portion of a, Geiger- Miiller tube and form a gastight seal therewith, said conducting member having a tubular portion projecting from said flattened portion and having attached contiguous to the terminal portion thereof and in gastight relationship therewith, an insulating member, said insulating member projecting both inwardly and outwardly of said flattened annular surface, and a conductor mounted within said insulator and insulated thereby from said conducting member, said conductor serving to conduct electricity to the interior of the Geiger-Muller tube.

12. A Geiger-Muller tube having a conducting outer cylindrical member, an end closure for said member having a flattened surface engaging with said cylindrical member, said closure having an insulating tube projecting inwardly from the plane of said flattened surface so as to project into the active volume of the Geiger-Muller tube, and. a conductor mounted in gastight relationship to said insulating tube to conduct electricity into the interior of the Geiger-Muller tube.

13. In a closure member for a Geiger-Muller tube, a conducting sleeve, insulator and central conductor, said sleeve, insulator and conductor being mounted co-axially of one another with annular spaces therebetween and being sealed in gastight relationship to one another contiguous to the terminal portions thereof, said sleeve being adapted to be attached to a Geiger-Muller tube to form a gastight closure therefor, said conductor serving to conduct electricity to the interior of the Geiger-Muller tube.

14. In a Geiger-Muller tube, means mounted in a wall thereof to conduct electricity to the interior of said tube, said means including an outwardly projecting insulator extending beyond said wall and forming a cavity outwardly of said wall, an electrical conductor within said insulator and a conducting sleeve external of said insulator said sleeve being attached to said wall in gastight relationship thereto.

SHELLEY KRASNOW. MEYER JOSEPH TEST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Dunning et al.: Rev. of Scien. Inst, August 1935, pp. 243-246.

Evans et al.: Rev. of Scien. Instr., December 1936, pp. 442-443.

Strong: Procedures in Experimental Physics, Prentice-Hall Inc., New York, 1938, pp. 281-282.

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