US2654041A - Radiation counter - Google Patents

Description

Sept. 29, 1953 w. H. MCCURDY E-T AL RADIATION COUNTER Filed June 1, 1950 INVENTORS c O PL/9Y Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE 2,654,041 RADIATION COUNTER William H. McCurdy, Caldwell, John H. Findlay, Upper Montclair, and Leo 0. Werner, Bloomtion of Pennsylvania J., assignors to Corporation, East Pitts Westinghouse Electric burgh, Pa., a corpora- Application June 1, 1950, Serial No. 165,554 3 Claims. (01. 31393) This invention relates to radiation counters and, more particularly, to those of the Geiger- Mueller type.

The principal object of our invention, generally considered, is to produce simple, cheap and quickly-assembled radiation counters.

our invention is to provide protecting the exhaust tip and anode standard A connector cap.

An additional object of our invention is to improve the metallic portion of a radiation counter envelope functioning as the cathode, by expanding one end portion thereof to receive the radiation-permeable window, thereby avoiding the necessity of machining an expanded end portion from heavy walled tubing.

Other objects and advantages will parent as the description proceeds.

In the drawing:

Fig. 1 is an axial sectional view, partly broken away, of a radiation counter embodying our invention.

Fig. 2 is a transverse sectional view on the line II II of Fig. 1, in the direction of the arrows.

g. 3 is an exploded view of the counter of Figs. 1 and 2, with portions broken away.

Geiger-Mueller counters as heretofore proposed, have been relatively expensive, particularly in the formation of the anode assembly. For example, such include a chrome iron anode wire, a machined ferrule which is threaded on the inside, also a machined anode connection stud which is made secure in the ferrule by a lock washer. This assembly is lathe-sealed. Before sealing the ferrule is glassed, flared, and finally the assembly is tubulated by hand. This makes the construction costly, as it involves considerable become apmounting and sealing time, as well as expensive machining operations.

It has also been costly to machine the cathode portion of the envelope from heavy walled tubing. The heavy wall was necessary to provide means for sealing the mica Window to the body of the cathode.

We propose to purchase thin-walled material and expand the same to provide a ledge in which fits the mica or radiation-permeable window, whereby savings are possible. This flaring or expanding may be accomplished by means of an hydraulic press, a useful machine for the purpose being the Vaille tubing end-forming machine.

Referring to the drawing in detail, like parts being designated by like reference characters, there is illustrated a radiation counter H of the cathode, and a vitreous or glass portion M of which serves for connection with an end closure member or metallic cap l5.

Instead of forming the metallic portion I! of thick material and machining an enlarged end, as indicated at 16, it is proposed to make said metallic portion thin and form the end flange [6 by expanding it in a hydraulic press. This flange 56, being of a diameter larger than the body portion [2, results in an annular portion or ledge l1 radiation-permeable closure disc [8, the peripheral portion of which is sealed to the flange I 6 in a conventional manner, indicated at I 9.

The other end portion of the metallic part of is sealed to the vitreous or glass portion M by fusion and embedding, as indicated at 2|. The portion 14 is desirably coated exteriorly with a silicone oil or other Water-repellant film 31, to prevent surface leakage, after being connected to the anode assembly. The latter is formed as will now be described.

In order to simplify and cheapen the construca closure cap l5 which is identical with that now used as the standard lumiline lamp base cap or'cup. However, it will be understood that we do not Wish to be limited to such construction, as a thin metal member with an interior knob and formed of nickelcobaltiron alloy, such as designated Kovar by the assignee of the present application, or other metallic material which seals satisfactorily to the glass of the enclosing envelope, may be used.

In a preferred embodiment, however, the anode comprises a relatively long chrome-iron wire 22,

of a length depending on the length of the device being made, and desirably about .03" in diameter, terminating at its free end in an insulative small ball or knob 23, and welded to a slit chromeiron ring 24, of wire .05 in diameter, as indicated at 215. Inorder to rigidity the connection between the wireZQ and the ring 21%, wepreierably employ a pair of relatively short chrome- iron wires 26 and 21, about 1" in length, but otherwise like the wire 22, connected to the ring 24 like the connection between the wire 22 and said ring, but spaced from said wire and each other approximately 120 around the periphery of said ring. All of said wires extend at approximately right angles to the plane of the ring, The .iree ends of the wires 26 and 21 are then brought toward and welded to an intermediate portion of the wire 22 as indicated at 28, all of said wires being suitably bent so that the base of the anode member, or where it connects with the ring, is like the out- 111164.01? a triangular pyramid.

The ring 24 is then snapped over the interior knob .29 on the cap l5, it being of diameter suitable ior that purpose, and securely holds the anode wire 22 in position, axial of the enclosing envelope. The wire of the ring 24 desirably has a radius larger than that of the curvature of the neck :of the knob 29 at the place of engagement, so that there are two lines of contact around the periphery, as illustrated .in Fig. 1, thereby insurin-g stability. Said knob, as is illustrated, has an exhaust aperture 3|, and an exhaust tube 32 is fused to the exterior surface of said cap inside of the externally-opening pocket produced by forming the knob 29.

After providing of the cap, ring,

the anode assembly consisting and wire 22 rigidified by the short wires 26 and 21, the same after inserting the anode wire 22 in the envelope 12, as illustrated in Fig. l, is sealed to the free end of the vitreous .or glass cylinder 14, referably using radio frequency power for heating. It is round that such a seal can be made in approximately seconds. Gas heating is satisfactory.

After exhausting, the envelope is filled with the customary inert gas admixed with a quenching material such as chlorine, alcohol or suitable organic substance. The exhaust tube 32 is .sealed off as indicated at 3'3, and the stub protected by securing a cup 34 thereover, as indicated most clearly in Fig. l. This cup may likewise be formed of chrome-iron or other suitable metal, and the periphery is formed with a bead 35 and radial slits 36, said bead being of such a normal diameter that it will snap into the external pocket formed in the cap I5 and effectively protect the exhaust tip 33. The end portion of the cup is desirably made the same size as the standard connector cap used with devices of this type. The completed counter is usable in a conventional circuit.

Although a referred embodiment of our invention is disclosed, it will be understood that modifications will be made within the spirit and scopeof the appended claims, and that the structure, although specially designed for Geiger tubes, is adapted for other electrical devices having an axially-extending electrode in an elongated envelope.

We claim:

l. In a radiation counter, in combination, a hollow cylindrical thin metal cathode member having one end iormed with an outwardly expanded cylindrical flange of a larger diameter than that of, and resulting in an annular ledge at the junction with, the main body of said member, a mica window member engaging said ledge, surrounded by said flange and sealed thereto, a hollow cylindrical insulator member extending from the other end of :said cathode member, a metal cap with its peripheral edge sealed to and closing the free end of said insulator member, said cap having a knob-like inner protuberance, and an anode member formed as a rod with its major portion extending axially of said cathode member and carrying a split ring which resiliently engages over said protuberance, said ring being connected directly to an end portion of said rod bent :at an angle to the axially extending portion, and rods extending diagonally from points on said ring spaced about from the point of connection of the anode member rod and with their ends respectively connected to said ring and said anode member rod adjacent said bend for bracing the connection to the ring.

.2. in a radiation counter, in combination, a tubular envelope comprising a metallic portion in the form of a cylindrical sleeve, .a split ring of metal wire about .05 in diameter, a relatively long wire about .03 indiameter one end of which is connected thereto .at nearly right angles to its plane to function as the anode, .a pair of short wires of materialcorresponding with that of said long wire connected at .nearly right angles to said ring, about 120 from said anode wire and each other, the free ends of said short wires being connected to an intermediate portion of said long wire to define a triangular pyramid, terminating in the remainder of said long wire projecting axially from said ring, one end of said sleeve being extended by .a hollow vitreous member, a metal end cap closing the free end of said vitreous member, .said cap having a hollow knob formed on its interior, said ring resiliently gripping said knob to hold said anode wire in place, an exhaust tube projecting outwardly from the interior surface of said knob which defines an outwardly opening pocket, and a radiation permeable window closing the other end of said envelope.

'3. In a radiation counter, in combination, a tubular envelope comprising a metallic portion in the form of a cylindrical sleeve, a split metal ring, a relatively long wire one end of which is connected thereto at nearly right angles to its plane to function as the anode, .a pair of :short wires connected to nearly right angles to said ring, about 120 from said anode wire and each other, the free ends of said short wires being connected to an intermediate portion of said long wire to define a triangular pyramid, terminating in the remainder of said long wire projecting axially from said ring, one end of .said sleeve being extended by a hollow vitreous member, a metal end cap closing the free end of said vitreous member, said cap having a hollow knob formed on its interior, said ring resiliently gripping said knob to hold said anode wire in place, an exhaust tube proiecting outwardly from the interior surface of said knob which defines an outwardly opening pocket, a radiation permeable window closing the other end of said envelope, and means covering said exhaust tube comprising a'cup member, the periphery of which is formed with a bead and radial slits dividing said bead into segments on the ends of fingers, said bead being of such a normal diameter that it 6 will snap into such outwardly-opening pocket Number Name Date and resiliently hold said cup in place. 2,452,524 Metten Oct. 26, 1948 WILLIAM H.7MCCURDY- 2,465,821 smoluchowski Mar. 29, 1949 JOHN H. FINDLAY. 2,479,201 Bleeksma, Aug. 16, 1949 LEO C. WERNER. 5 2,489,850 Baker Nov. 29, 1949 References Cited in the file of this patent OTHER REFERENCES Rev. of Scientific Instruments, Copp. et a1.,vo1. UNITED STATES PATENTS 14, #7, July 1943, pp. 205-206. Number Name Date 2,434,779 Willis Jan. 20, 1948 2,447,159 Cartun Aug. 17, 1948

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