US2245787A - Examining bodies by means of neutrons and electron emitting material - Google Patents

Examining bodies by means of neutrons and electron emitting material Download PDF

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US2245787A
US2245787A US270354A US27035439A US2245787A US 2245787 A US2245787 A US 2245787A US 270354 A US270354 A US 270354A US 27035439 A US27035439 A US 27035439A US 2245787 A US2245787 A US 2245787A
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layer
substance
neutrons
neutron
fluorescent
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Kallmann Hartmut Israel
Kuhn Ernst
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IG Farbenindustrie AG
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IG Farbenindustrie AG
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/05—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using neutrons
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/06—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
    • G01N23/09—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption the radiation being neutrons
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
    • Y10S430/154—Neutron beam

Definitions

  • Bodies or substances which absorb or disperse neutrons may be examined by means of neutrons, preferably slow neutrons, l. e. those of which the de Broglie Wave is approximately equal to or is greater than the diameter of the nuclei of the atoms of the body or substance. This may be done by directing a beam of neutrons on to the body or substance and causing the neutrons that emerge from it to act upon a layer of material in which a reaction takes place in which heavy charged particles are produced and these particles are in turn caused to act either upon a fluorescent material or directly upon an adjacent photographically-sensitive layer.
  • a disadvantage of this method is that the heavy particles have only a relatively short range in the material of the layer so that only a very thin surface layer is effective even of a thick layer of material, the thickness of this surface layer corresponding approximately to the range of the heavy particles in the material.
  • this disadvantage is obviated by employing a layer of a material in which the neutrons produce, not heavy charged particles, but positively or negatively charged electrons.
  • the shorter terms electrons and positrons respectively are sometimes used to denote these two difierent forms of electrons.
  • the single term electrons is employed to denote positive or negative electrons.
  • the layer of material in which the reaction is caused by the neutrons will hereinafter be referred to as the neutronreactive layer, although the material need not be in the form of a layer but may be finely distributed in another substance. In this neutronreactive layer, radio-active nuclei are thus artificially formed, which nuclei, when they disintegrate, give off electrons.
  • a relatively thick neutron-reactive layer may therefore be used according to the invention so that the effect on fluorescent substance or on a photographic plate is greater, with the same intensity of the incident neutrons, than it is in the case of the heavy particles.
  • the neutron-reactive layer may be applied to the side of the fluorescent substance which is adjacent to the source of neutrons.
  • a non-transparent material may then be used for the neutron-reactive layer.
  • the substance that gives off the electrons may however be mixed with the fluorescent substance. In certain circumstances it is even of advantage to apply it to the side of the fluorescent substance which is on the far side of the source of neutrons during the exposure.
  • the neutronreactive layer must either consist of a material which is permeable to the rays emitted by the fluorescent substance or it must be applied in such a thin layer that undue absorption does not take place in the substance forming the neutron-reactive layer.
  • any substance which emits electrons under the influence of neutrons may in general be employed for the neutron-reactive layer.
  • Such substances are for example silver and its compounds, more especially silver chloride, rhodium, indium and yttrium and their compounds.
  • any substances which, under the influence of electrons, emit rays which are visible to the eye or act upon a photographic plate, may be employed as the fluorescent material.
  • Fluorescent zinc sulphide is especially suitable for this purpose.
  • the fluorescent substance may in certain circumstances be mixed with advantage with the substance which gives off electrons. It is especially advantageous to use a substance which, under the influence of neutrons, emits electrons and is itself caused by them to become luminous.
  • the visible radiation which proceeds from the fluorescent mass may either be observed by the eye or may be made to act, together with the invisible radiation, upon photographic material, for example on a photographic plate or a film.
  • the photographic layer may be embedded between two layers of fluorescent material at least one of which is covered with a layer of material which gives off electrons or is mixed with such a material.
  • the substances which give off electrons under the influence of the neutrons have for the greater part the property of giving off electrons not only directly after being exposed to the neutrons but also for a certain time after being exposed.
  • the manner in which the emission of electrons gradually ceases is determined by the mean life of the radioactive nuclei which are formed in the neutron-reactive layer by the bombardment with neutrons. The mean life varies according to the substance, between a very small fraction of a second and many days.
  • the photographic material serves to retain the latent image which is present in the intermediate layer in the form of radioactive nuclei and which has been produced there during the exposure to the slow neutrons.
  • the interval between the exposure to neutrons and the action upon the photographic material must be made shorter, the shorter the mean life of the artificial radioactive nuclei.
  • the neutron-reactive layer and the fluorescent substance may be used repeatedly because, when the emission of electrons dies away, the original condition is restored. Accordingly, it is in certain circumstances of advantage to make the neutron-reactive layer in the form of an endless band different parts of which are exposed to neutrons successively.
  • the fluorescent substance may be applied to this band-like carrier but in certain circumstances it is more advantageous to cause the intermediate layer to act upon a fluorescent screen which is not adjacent to it during exposure.
  • the neutron-reactive layer may be in the form of an endless band.
  • the substance forming the neutron-reactive layer may however be applied to an inactive support.
  • the fluorescent substance may also be arranged on this support or on a separate support.
  • the photographic material may also be applied to a separate support which may have any desired length. Pictures of moving objects may also be taken by proceeding in accordance with the invention. In this case it is convenient either to produce the neutrons intermittently or to expose the neutron-reactive layer to them only intermittently with an intermittent forward movement of the neutron-reactive layer.
  • the neutron-reactive layer may also be caused to act directly on the photographic material. If the intensity is adequate, a photographic image may be obtained in this manner without the interposition of a fluorescent substance.
  • the neutron-reactive layer is applied to the photographic layer of emulsion in the form of a liquid coating which subsequently solidifies, it is of advantage to apply it by means of a binding agent which dissolves in a solvent which does not attack the photographic layer or in the liquids which are necessary for development.
  • the fluorescent material In order to increase the action of the visible or invisible radiation from the fluorescent material there may in certain circumstances first be arranged near it a substance which emits heavy particles under the influence of slow neutrons, for example, a layer of boron or lithium or a substance containing boron or lithium. This layer is then covered with a layer which emits electrons under the influence of neutrons.
  • the arrangement may be such that the electrons pass through the layer of boron or lithium without undue hindrance so that the fluorescent material is caused to become luminous both by the heavy particles and by the electrons.
  • the fluorescent material and the substance which emits heavy particles may be applied on one side of the photographic layer and the substance which emits electrons on the other side. The electrons are able to penetrate the photographic layer if it is thin enough.
  • the neutron-reactive layer may therefore be composed of a number of thin neutron-reactive layers which are of such mechanical strength that after the exposure to the neutrons they may be applied individually to one, or between two, photographic layers, upon which they act directly by the electrons which are emitted or by means of the fluorescent material.
  • the latent image of a thick neutron-reactive layer composed of n-sub-layers is reproduced upon n or 2n photographic layers.
  • the thickness of the individual sub-layers is, in general, advantageously such that only a moderate, for example absorption of electrons takes place in it.
  • the time of exposure is selected so that it is of the order of magnitude of the mean lives of the radioactive neuclei of the neutron-reactive layer.
  • radioactive nuclei having different durations of life are in certain circumstances formed in the neutronreactive layer. Accordingly immediately after exposure both the electrons which are derived from radioactive nuclei having a short life and the electrons which originate from nuclei having a long life act upon the fluorescent material or upon the photographic plate. When some time has elapsed after exposure only the electrons which originate from radioactive nuclei having a long life act upon the fluorescent material or the photographic plate. Separation of the effect of the long-life latent image from the short-life image may be effected by appropriate choice of the time of exposure to neutrons, of the instant at which copying begins and of the duration of copying.
  • Fig, 1 is a diagrammatic representation of the method and device of the invention
  • Figs. 29 are diagrammatic representations in partial section of nine different embodiments of the image-forming device of the invention.
  • Fig. 10 is a diagrammatic representation in perspective of a modified embodiment of the method of the invention.
  • l represents a source of neutrons
  • 2 represents the body of which an image is to be obtained by means of the neutron beam which is partially absorbed in the body.
  • the neutrons passing body 2 impinge on the substance or a photographic layer.
  • stance 3 which reacts with the neutrons with the emission of electrons.
  • the electrons emitted by substance 3 act upon an electron-sensitive substance 4, for example, a fluorescent sub-
  • the layer of neutron-sensitive substance 3 and the layer of electron-sensitive substance 4 are carried on supporting layer It which, if layer 4 is a fluorescent substance, is preferably transparent. 5 indicates the image of object 2 which would be visible if layer 4 is a fluorescent substance or which could be made visible by development if layer 4 is a photographic material.
  • 6 is a layer of substance which reacts with neutrons with emission of electrons mixed with fluorescent material and supported on supporting member I.
  • an electron-sensitive layer 8 is carried upon a support 9 and a layer of substance which reacts with neutrons with the emission of electrons is applied at 9.
  • the electron-sensitive layer 8 can consist, for example, of a fluorescent material or of a photosensitive material.
  • fluorescent material may be mixed with the electronemitting substance in layer 9.
  • the electron-sensitive substance of layer 8 is a fluorescent substance, it is advantageous to use a transparent substance for the electron-emitting substance 9.
  • the electron-emitting substance 9 may consist of a substance which becomes radio-active under the influence of the impinging neutrons.
  • Layer 8 may consist of a mixture of a substance sensitive to charged particles with a substance containing boron or lithium or a substance containing boron or lithium may be mixed with the neutron-sensitive substance in layer 9 and layer 8 may be a substance sensitive to charged particles.
  • the device shown in Fig. 4 comprises three active layers carried on a supporting layer [0.
  • Layer ll consists of' a neutron-sensitive substance
  • layer I2 is an electron-sensitive substance, preferably a fluorescent material
  • layer It is a photosensitive substance.
  • Layer l2 may also consist of a neutron-sensitive substance and layers II and I 3 of a photosensitive substance, preferably mixed with a fluorescent substance.
  • Layer Il may consist of a fluorescent substance, layer l2 of a transparentneutron-sensitive substance and layer I3 of a photographic material, in which case the fluorescent radiation from layer II passing through transparent layer l2 produces a latent image in layer I3.
  • Layer ll may consist of an electron-emitting neutron-sensitive substance and layer l2 of an electron-sensitive substance, and layer l3 can include an additional neutron-sensitive substance containing boron or lithium in order to increase the effect.
  • the electron-sensitive layer can consist either of fluorescent substance or photosensitive substance.
  • the neutron-sensitive substance in layer I4 is opaque and is provided with a plurality of perforations l5 through which the radiation issuing from fluorescent layer Hi can pass.
  • This arrangement is of importance when the supporting layer in is opaque and when it is desirable not to apply the fluorescent layer on the side of the neutron-sensitive layer available to the observer.
  • of neutron-sensitive substance is attached to a layer of photosensitive material by means of a soluble binding agent 22, the photosensitive layer being supported by support H).
  • a layer 24 of neutron-sensitive substance, a layer 25 containing boron or lithium, a fluorescent layer 28, and a photosensitive layer 21 are carried on support ill.
  • the sequence of the layers may be varied.
  • two fluorescent layers and 3! and a layer of photosensitive material 32 are provided together with a neutron-sensitive layer 28. Since the photosensitive layer 32 is sensitive to the electrons issuing from the neutron-sensitive layer 28, the fluorescent layers 33 and 3! can be omitted if the intensity of the neutron radiation is great enough.
  • each group consisting of a layer of electron-emitting, neutron-sensitive substance 33, fluorescent layers 34, and a photosensitive layer 35.
  • Three groups of such layers in the example shown are carried by a common support Ii]. If the neutron radiation is intensive enough. the fluorescent layers 34 may be omitted as explained in connection with Fig. 8.
  • an endless strip 35 carried on rollers bears a layer 31 of electronemitting, neutron-sensitive substance.
  • the neutron-sensitive substance 39 is exposed to a beam of neutrons from source I passing through the object 2 to be examined and impinging on the neutron-sensitive layer at 39.
  • the layer is then advanced by rotation of the rollers 40 to bring area 39 adjacent a layer of electron-sensitive substance 4
  • the electron-sensitive substance may consist either of fluorescent material or of photosensitive material or a mixture of two such materials.
  • An electron-sensitive material, for example, fluorescent material may be mixed with the neutron-sensitive substance in layer 31 or a layer of fluorescent substance may be applied on the endless strip in addition to the neutron-sensitive layer.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object and causing the emergent beam of neutrons to impinge upon a layer comprising a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance sensitive to the emitted electrons.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object and causing the emergent beam of neutrons to impinge upon a layer comprising a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a fluorescent material.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object and causing the emergent beam of neutrons to impinge upon a layer comprising a substance which reacts with neutrons to form an electronemitting substance, said layer also comprising a photosensitive material.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object and causing the emergent beam of neutrons to impinge upon a layer comprising a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a fluorescent substance, and a photosensitive material.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object and causing the emergent beam of neutrons to impinge upon a layer comprising a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance selected from the group consisting of boron, lithium and compounds thereof, and a substance sensitive to the emitted particles.
  • a method for obtainin an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object and causing the emergent beam of neutrons to impinge upon a layer comprising a substance which reacts with neutrons to form an electronemitting substance, said layer also comprising a substance selected from the group consisting of boron, lithium and compounds thereof, and a photosensitive material.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object, causing the emergent beam of neutrons to impinge upon a layer containing a substance which reacts with neutrons to form an electron-emitting radioactive substance, and exposing a layer of substance sensitive to the emitted electrons, to said first-named layer after the latter has been exposed to said emergent beam of neutrons.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object, causing the emergent beam of neutrons to impinge upon a layer containing a substance which reacts with neutrons to form an electronemitting radioactive substance, said layer also comprising a fluorescent substance, and exposing a photosensitive layer to said first-named layer after the latter has been exposed to said emergent beam of neutrons.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object, caus ing the emergent beam of neutrons to impinge upon a plurality of separable adjacent layers, each containing a substance which reacts with neutrons to form an electron-emitting radioactive substance, and thereafter exposing a separate layer of a substance sensitive to the emitted electrons to each of said first-named layers.
  • a method for obtaining an image of an object by means of neutrons which comprises directing a beam of neutrons upon the object, causing the emergent beam of neutrons to irnpinge upon a layer containing a substance which reacts with neutrons to form a plurality of electron-emitting substances of different mean lives, and thereafter exposing a plurality of separate photosensitive layers to said first-named layer, the time of each successive exposure being of the order of the mean life of one of the radioactive components of said first-named layer in the order of increasing mean life periods of said components.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance sensitive to the emitted electrons.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to forman electron-emitting substance, said layer also comprising a fluorescent material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a photosensitive material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a fluorescent material, and a photosensitive material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance selected from the group consisting of boron, lithium and compounds thereof, and a substance sensitive to the emitted electrons.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance selected from the group consisting of boron, lithium and compounds thereof, and a photosensitive material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance selected from the group consisting of boron, lithium and compounds thereof, and a fluorescent material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a substance selected from the group consisting of boron, lithium and compounds thereof, a fluorescent material, and a photosensitive material.
  • a device as defined in claim 11 in which the neutron-reactive substance is arranged in layers on both sides of a layer of the electronsensitive substance.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a fluorescent material, said neutron-reactive substance being permeable to the radiation emanating from the fluorescent material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer containing a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a fluorescent material, said neutron-reactive substance being impermeable to the radiation emanating from the fluorescent material and being perforated to allow the passage of said radiation.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer of photosensitive material, and a substance which reacts with neutrons to form an electron-emitting substance bound to said layer of photosensitive material by means of a binder composition soluble in a solvent which does not affect the photosensitive material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer of photosensitive material, and a substance which reacts with neutrons to form an electron-emitting substance, said layer also comprising a fluorescent material bound to said layer of photosensitive material by means of a binder composition soluble in a solvent which does not affect the photosensitive material.
  • a device for forming an image of the distribution of the intensity of a beam of neutrons comprising a layer of photosensitive material, a substance which reacts with neutrons to form an electron-emitting substance on one side of said layer of photo-sensitive material, and a fluorescent material and a substance selected from the group consisting of boron, lithium and compounds thereof on the other side of said layer of photosensitive material.

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US270354A 1938-05-05 1939-04-27 Examining bodies by means of neutrons and electron emitting material Expired - Lifetime US2245787A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4814623A (en) * 1985-05-08 1989-03-21 University Of New Mexico Pulsed neutron detector
US5635727A (en) * 1994-07-19 1997-06-03 Fuji Photo Film Co., Ltd. Method for forming neutron images

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4814623A (en) * 1985-05-08 1989-03-21 University Of New Mexico Pulsed neutron detector
US5635727A (en) * 1994-07-19 1997-06-03 Fuji Photo Film Co., Ltd. Method for forming neutron images

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FR859976A (fr) 1941-01-03
CH217067A (de) 1941-09-30

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