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Publication numberUS2344042 A
Publication typeGrant
Publication date14 Mar 1944
Filing date3 Jul 1941
Priority date15 Mar 1940
Publication numberUS 2344042 A, US 2344042A, US-A-2344042, US2344042 A, US2344042A
InventorsErnst Kuhn, Israel Kallmann Hartmut
Original AssigneeErnst Kuhn, Israel Kallmann Hartmut
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Neutron image converter
US 2344042 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

. l. KALLMANN ET AL.

NEUTRON IMAGE CONVERTER Flled July 3, 1941 arch E4, 1944.,

Patented Mar. 14, 1944 NEUTRON IMAGE CONVERTER o Hartmut Israel Kallmann, Berlin-Charlottenburg, and Ernst Kuhn, Berlin, Germany;

vested in the Alien Property Custodian Application July 3, A194.1, Serial No. 401,038 In Germany March 15, 1940 (Cl. Z50-65) Claims.

A device for the production of visible or photographic images of objects with employment of neutrons as depicting radiation has been proposed, in which in a neutron-reactive layer heavily charged particles or electrons are produced by the depicting neutrons, and these charged particles or electrons release in the neutron-reactive layer or in a neighboring layer slow electrons, which are accelerated by electric fields and, after they have passed through an electron-optical system, produce a picture on a luminescent screen or on a photographic layer. With this device it is possible to produce pictures very rich in contrast even with a neutron radiation of low intensity.

In the production of such a neutron-imageconverter diiculties are caused by the fact that the neutron-reactive layer and the layer from which the slow electrons are released react the one with the other in undesired manner during the production ofthe image-converter, for instance during the baking out of the vacuum tube. Some neutron-reactive layers also partly lose their eiciency during the heating to the higher temperatures which cannot conveniently be avoided in the course of the production of the image-converter.

It is an object of the present invention to obviate these dliiiculties involved in the production of the apparatus formerly described. For this and other inventive purposes the neutron-reactive layer is positioned outside the vacuum space, and at this point the wall of the vessel is made transparent to the radiation serving for releasing the slow electrons.

In a neutron-image-converter, in which the heavily charged particles or electrons produced in the neutron-reactive layer by the depicting neutrons release in a neighboring luminescent mass a radiation, which in turn releases slow electrons in a neighbouring layer, it is advisable under certain circumstances to position the luminescent mass also outside the vacuum tube. For intensifying the eect, a surface which refleets the radiation emitted by the luminescent mass and transmits the charged particles which excite the luminescent mass, is preferably provided on the side of the luminescent mass remote from the vacuum space.

For reducing unsharpness and losses from reiiection on the wall of the tube, it is advisable to apply directly upon the wall the neutronreactive mass or the luminescent mass, or, if desired, both masses mixed together.

If in the neutron-reactive mass electrons are produced which in turn have to release slow electrons in the interior of the vacuum space from another layer, the wall of the tube at this point must transmit the electrons released from the neutron-reactive layer.

Some substances for the neutron-reactive layer, for instance metallic lithium, are especially affected by moist air, so that their eiiiciency decreases gradually. For increasing their durability it is therefore advisable in such masses for neutron-reactive layers. and similar sensitive luminescent masses, to house the neutron-reactive mass, if desired together with the luminescent mass and the reflecting layer, in the interior of a closed space adjoining the wall of the vacuum tube, said space being evacuated or ,filled with a gas which does not affect said substances.

Embodiments of the arrangement according to the invention are shown partly in diagrammatic illustration in the iigures of the accompanying drawing, in which Fig. 1 is a section through a complete apparatus,

Fig. 2.is a fragmentary section of a modified arrangement in which layers 6 and 9 are omitted,

Fig. 3 is a fragmentary section in which layers 5, 6 and 9 are enclosed.

Referring to the drawing, the neutron beam 2 kserving for depicting starts from the source of neutrons I and traverses the body 3 to be depicted. The depicting neutron radiation 4 impinges upon the neutron-reactive layer 5 arranged outside the vacuum space and produces in this layer heavily charged particles or electrons. The intensity or concentration of the thus produced heavily charged particles or electrons is different from place to place according to the intensity distribution of the neutron radiation locally weakened by passage through the body 3. The heavily charged particles or electrons release in the adjacent layer 6 of luminescent mass a radiation, which passes through the wall 1 of the tube, which at this point is transparent to such radiation, into the vacuum space and releases there slow electrons from a photosensitive layer 8. These slow electrons are accelerated and can be collected electron-optically in a manner known per se upon a luminescent screen I2 or upon a photographic layer to produce an image of the object.

Between the layer 6 of luminescent mass and the neutron-reactive layer 5 a reflecting surface 9 -may be provided for intensifying the effect, said surface reecting the radiation emitted by the luminescent mass through this mass itself into the interior or the vacuum space upon the photosensitive layer. This surface t trts the heavily charged particles or electrons produced by the neutrons in the layer 6.

The luminescent mass and the neutron-reactive layer mass may be applied directly onto the wall 'I oi' the tube the one mixed with the other as well as singly.

The wa1l must be such that it transmits electrons in case electrons are emitted from the neutron-reactive layer .5 which, in the i'orm of construction shown in Fig. 2, is directly adjacent to the wall, said electrons having to release slow electrons from the layer l which is in the interior.

In the embodiment shown in Fig. 3, the neutron-reactive layer 5, the luminescent mass 6 and the reecting layer s are housed in a cap I0 directly adjacent to the wall and evacuated or lled with a gas which does not aiIect the said masses.

An advantage of the arrangement according to the invention consists in that. without alteration of the evacuated image-converter-tube, the neutron-reactive layer in which the heavily charged particles or electrons are produced by the depicting neutronscan be exchanged. It is therefore possible to adapt the apparatus to neutrons of diiIerent speeds with the same imagev converter-tube merely by exchanging the neutron-reactive layer or luminescent mass.

As examplesof the'compostions of the various elements disclosed, the neutron reacting plate 5 may be of lithium where the plate is enclosed, as .in Fig. 3, or boron or uranium where the plate is exposed, or it may be a composition vcontaining these elements. Reector l may be a thin sheet of whiteor optically opaque glass or ceramic material. 'I'here are many materials which may be employed as the fluorescent screens 8 and I 2; among them are barium platino-cyanide or cal'- clum-tungstate; The wall oi' the exhausted container may be of thin glass. y

Asa source of neutrons a device maybe employed which subjects beryllium to a bombardment of alpha particles.

We claim:

1. A device for the production oi' visible or photographic images by means oi.' neutrons, comprising a vacuum tube; a source of neutrons located outside the tube, a neutron reactive layer located outside the tube and adjacent a wall thereof and in the path of neutrons from said source, a luminescent mass located outside the vacuum tube and adjacent said wall, said mass' being exposed to and capable of being energized by charged particles liberated by the neutron reactive layer, a reflecting surface capable of transmitting charged particles liberated by the neutron reactive layer and reflecting the radiation liberated. by the luminescent mass. said surface, being positioned on the side of said mass opposite that nearest to the wall of the tube, a photo-l sensitive layer within said vacuum tube adja, cent said wall, said layer being capable of liber ating slowY electrons under the action of the radia.

tion transmitted through said wall, means for accelerating said slow electrons, an electronsensitive screen and an electron Voptical system for focusing the electrons, after acceleration, on

said screen.

2. A device as defined in claim 1 in which the wall of the vacuum tube between the neutron reactive layer and the photosensitive layer is capable of transmitting charged particles liberated by said neutron reactive layer.

3. A device as dened in claim 1 comprising a luminescent mass located outside of the vacuum tube and adjacent to said wall, said `mass being exposed to and capable of beingr energized by charged particles liberated by the neutron reactive layer, the material constituting the neutron reactive layer and the material constituting the luminescent mass being in the form of a mixture :onstituting a layer on the wall oi' the vacuum ube.

4. A device as deilned in claim 1 comprising an enclosed space outside the vacuum tube surrounding the neutron sensitive layer.

5. A device as dened in claim 1 comprising a luminescent mass located outside of the vacuum tube and adjacent to said wall thereof and an enclosed space outside the vacuum tube enclosing said luminescent mass and the neutron sensitive layer.

HARTMUT ISRAEL KALIMANN. ERNST KUHN.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2439181 *17 May 19466 Apr 1948Rca CorpLuminescent screen
US2527913 *4 Aug 194831 Oct 1950Radio Industrie SaPhotoelectric device
US2534932 *19 Jun 194719 Dec 1950Westinghouse Electric CorpMethod of detecting elementary particles
US2541599 *31 Oct 194413 Feb 1951Philip MorrisonRadiography
US2549176 *31 May 194717 Apr 1951Texas CoDetection of scattered neutrons
US2549574 *8 Jul 194817 Apr 1951Archer Daniels Midland CoApparatus for making fluorophotometric measurements
US2555423 *16 Apr 19475 Jun 1951Emanuel Sheldon EdwardImage intensifying tube
US2586392 *9 Dec 194819 Feb 1952Emanuel Sheldon EdwardMotion-picture camera for chi-ray images
US2608661 *16 Oct 194526 Aug 1952Zinn Walter HMeans for measuring radiation
US2642535 *18 Oct 194616 Jun 1953Rca CorpMass spectrometer
US2681868 *10 Aug 194922 Jun 1954Westinghouse Electric CorpImage amplifier
US2690516 *21 Apr 194828 Sep 1954Emanuel Shcldon EdwardMethod and device for producing neutron images
US2697181 *1 Jun 195114 Dec 1954Emanuel Sheldon EdwardNeutron sensitive tube
US2717971 *30 Mar 194913 Sep 1955Emanuel Sheldon EdwardDevice for storage of images of invisible radiation
US2727183 *22 Dec 194813 Dec 1955Westinghouse Electric CorpRadiation detector of the scanning type
US2739258 *19 May 195020 Mar 1956Sheldon Edward ESystem of intensification of x-ray images
US2748304 *1 Mar 195129 May 1956Hartford Nat Bank & Trust CoElectric discharge tube for intensifying fluorescent images produced with the use ofchi-rays
US2782332 *6 Apr 194919 Feb 1957Emanuel Sheldon EdwardMethod and device for reading images of invisible radiation
US2804561 *1 Jun 195127 Aug 1957Emanuel Sheldon EdwardChi-ray camera
US2894159 *1 Jun 19517 Jul 1959Emanuel Sheldon EdwardElectronic system for x-ray images
US2994769 *29 Apr 19571 Aug 1961Westinghouse Electric CorpScintillation counter
US2994773 *20 Feb 19561 Aug 1961Westinghouse Electric CorpRadiation detector
US3149230 *11 Jun 195915 Sep 1964Texaco IncFormation hydrogen content logging with fast neutron and scintillation detector
US3457408 *12 Dec 196622 Jul 1969Gen ElectricTrack-etch neutron radiography
US4587555 *1 Dec 19836 May 1986Ltv Aerospace And Defense Co.Neutron and X-ray radiation combined inspection means and method
Classifications
U.S. Classification376/153, 250/367, 250/390.11, 250/390.2, 376/159, 313/527, 250/486.1
International ClassificationH01J29/38, H01J29/10
Cooperative ClassificationH01J29/385
European ClassificationH01J29/38B