Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F1/00—Shielding characterised by the composition of the materials
  • G21F1/12—Laminated shielding materials
  • G21F1/125—Laminated shielding materials comprising metals
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F1/00—Shielding characterised by the composition of the materials
  • G21F1/12—Laminated shielding materials
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
  • G21K1/10—Scattering devices; Absorbing devices; Ionising radiation filters

Definitions

• the present invention refers to a laminar structure for influencing the effect of X-ray or gamma radiation on a target sensitive to the radiation which comprises at least two groups of layers wherein each group of layers emits a secondary radiation under the influence of the X-ray or gamma radiation or the secondary radiation of the previous layers.
• the structure proposed by the invention is capable of improving quality of a picture received by the means of the radiation and it can be applied also for securing protection of increased safety level against X-ray and gamma radiation.
• a method and a modifying body for influencing the effect of X-ray or gamma radiation on a target sensitive to the given kind of radiation and in particular for selective modification of a radiograph of an object is known from the U.S. Patent Document 4764946 (granted to P. Teleki in August 1988), wherein the effect of the X-ray or gamma radiation is proposed to be influenced by the means of a structure comprising at least two layer groups intended to modify the energy spectrum of the radiation in order to ensure increased level of excitation in a substance sensitive to radiation, e.g. in an AgBr layer prepared for making X-ray radiographs.
• the layer groups include different metals, especially antimony ( 51 Sb) and strontium
• the method and modifying body disclosed in the mentioned U.S. patent specification offers a very simple solution for improving the conditions of preparing X-ray radiographs especially in industrial applications.
• the metals forming the layer groups ensure a gradual energy transposition from one layer to the other by excitation. In this method the energy transposition is the basis of improving the quality of the received radiographs.
• the reflection of the beams constituting X-ray or gamma radiation is a problem difficult to solve.
• the known X-ray mirrors include a plurality of thin film layers, e.g. about 80 to 100 layers made alternatively of tungsten and carbon.
• the thickness of the layers in the systems which have become known is comparable with the wavelength of radiation applied.
• the level of the scattered radiation is relatively high what results in the fact that the quality of the visible radiographs received is rather poor.
• the object of the present invention is to provide a more layer structure for influencing the effect of X-ray or gairma radiation, in particular for improving the quality of pictures received by the means of radiography and/or for increasing the safety level of means ensuring protection against the mentioned kinds of radiation.
• the invention is based on the recognition that the thin layer structures can be applied for controlled scattering the radiation. This means, depending on the composition the structure can be applied for absorbing radiation and simultaneously or only for reflecting radiation in a manner which results in improved quality of the radiographs.
• the X-ray or gamma radiation is scattered. It is also known that the primary back- scatter phenomenon of extinction results in improved conditions of scattering and in absorbing radiation having relatively low energy. In a system comprising many reflecting layers the Compton effect shows also changes in a series of interactions, the radiation becomes softer (its energy decreases) and this is advantageous in protecting systems.
• the intensive scattering process is also preferred in protecting structures having thickness exceeding a minimal value because of ensuring a longer way for the propagation of the radiation in the material of the structure; this results in improved absorption conditions.
• the mechanism shown here can be influenced by doping the material, by controlling the crystallization process thereof.
• the invention refers to a laminar structure for influencing the effect of X-ray or gamma radiation on a target sensitive to the radiation which comprises at least one group of layers wherein the only one or each group of layers emits a secondary radiation under the influence of the primary X-ray or gamma radiation or the secondary radiation of the previous layers.
• the essence of the invention is to provide a structure including the layers in at least one group, the layers being arrranged in a predetermined space sequence which can be symmetric with regard to basic materials applied.
• the predetermination means that the layers are arranged in the sequence of the atomic numbers of the elements constituting them, if a reflecting system is required.
• the layer system to be applied for reflecting X-ray or gamma radiation should consist of at least 32 layers with preferred thickness in the range from 0.0001 to 0.01 mm, wherein the value range from about 0.001 mm to about 0.002 mm is especially advantageous.
• the group of the layers should include at least one layer made of 82 Ph (lead), 74 W (tungsten) or 73 Ta (tantalum) and the further layers can be made from at least one of the following metals:
• the elements of the first group are characterized with crystalline lattice built-up according to the face-centered system (FCC) and those of the second group with lattice of body-centered system (BCC). If the proposed structure is intended to ensure reflexion of X-ray or gamma radiation it is important to prepare the layers with homogeneous distribution of their material having as low density of dislocations and level of contamination as possible.
• FCC face-centered system
• BCC lattice of body-centered system
• the structure proposed by the invention if contaminated and includes dislocations may be applied also for increasing the safety level of protecting systems applied in an environment of X-ray or gamma radiation and this effect is increased by applying before the layers defined above and/or between two of them an iron based body made of iron including at least four of the following additives: 15 P, 16 S, 27 Co, 39 Y and 40 Yr.
• Iron completed with the mentioned additives and the physical and chemical contamination of the crystalline lattice, i.e. the dislocations and the strange atoms exert intensive scattering effect on X-ray or gamm a radiation entering the structure and the scattered beams of radiation can be absorbed or reflected by the structure more intensively than the beams entering directly.
• the dislocations and the strange atoms constitute centers of the scattering process.
• the proposed structure can be equipped with a protective layer arranged on the outer surface (on the first side striked by radiation), the protective layer being comprised of 24 Cr or another substance showing high resistance against different corrosive and other dangerous factors.
• the structure built-up according to the invention can be applied in the cosmic space and in normal gravity conditions. It constitutes a system of relatively low density which can be easily realized.
• FIG. 1 is a schematical view of a two-layer basic embodiment of the structure proposed by the invention, the structure advantageously being equipped with a scattering layer
• FIG. 2 is a schematical view of another basic embodiment of the structure proposed by the invention comprising more (e.g. ten) layers in a symmetric arrangement
• FIG. 3 is a schematrical view of a preferred arrangement of the layers of the structure proposed by the invention, the structure beg divided into subsystems of layers and
• FIG. 4 is a further schematical view of another preferred arrangement of the layers constituting a relatively sophisticated part of a structure proposed by the invention.
• the structure for influencing the effect of X-ray or gamma radiation on a target sensitive to the radiation consists of layers of equal or different thicknesses.
• the target arranged in the way of the reflected radiation produced by the structure proposed by the invention from primary radiation R is not shown in the drawings.
• the target can be a film being sensitive to X-ray or gamma radiation or a screen or any image-sensing means, e.g. Nal or Csl crystal detector doped by T1.
• the structure of the invention can be applied also, if the components allow to do so, for preparing a screen or shield protecting the environment against the X-ray or gamma radiation.
• the structure of the invention is consisted of a basic layer 1 and at least a second layer 3 (Fig. 1).
• the basic layer 1 is made of ooPb or 74 W or 73 Ta and the second layer 3 consists of any one of 47 Ag, 29 Cu, 28 Ni or 13 Al (metals associated generally with 82 Pb), 42 Mo, 41 Nb or 23 V (associated with 74 W and 73 Ta).
• the basic layer 1 is arranged either as the first in the way of radiation R after a scattering layer 2 (Fig. 1) and/or a covering layer 4 which will be described later or in the middle part of a symnetric layer system.
• the basic layer 1 is followed (Fig. 1) or preceded and followed (Fig. 2) by the second layer 3 and if necessary, by third, fourth and fifth layers 5, 7, 9 consisting of the other elements listed up above.
• the elements are arranged always in a sequence according to their increasing (structure as shown in Fig. 2) or decreasing (structure as shown in Fig. 1) atomic numbers given in the above lists, too.
• the second layer may be consisted of 73 Ta, too.
• the basic and further layers 1, 3, 5, 7, 9 of a reflecting system are made of metals crystallizing in the face-centered crystalline lattice (FCC) and/ /or in the body-centered crystalline lattice (BCC), characte rized with only one lattice constant.
• the elements are the following:
• the arrangement is built-up from symmetric pieces including the basic layer(s) 1 in the middle part (Fig. 3 and 4).
• the number of the layers is advantageously at least thirty-two, between two layers it is preferred to prepare separating layers 6 consisted of an appropriate oxide, having thickness not exceeding about 0.0001 mm.
• the invention renders possible to create material systems showing double effect.
• the layers 1, 3, 5, 7, 9 consist of a substance characterized by crystalline disorder, relatively high density of dislocations and/or prepared with selected alloying components or additives, they cause intensive scattering effect with backscatter phenomenon, i.e. scattering effect acting backwards practically without any remarkable order.
• the dislocations, the surface of the grains comprising the strange atoms consitute the centers of scattering. It is therefore advantageous to apply such layers 1, 3, 5, 7, 9 together with those prepared of pure material having low density of dislocations which act together as an active system reflecting the radiation.
• the scattering (protecting) layers 2 can include also the metals listed above. It is also advantageous to apply iron ( 26 Fe) for the basic material of a such layer, wherein iron comprises at least four of the following alloying components, additives and elements: 39 Y, 40 Zr, 27 Co, 15 P , 16 S.
• the thickness of the scattering layer 2 is not limited, however, it is proposed to prepare it with thickness lower than that of the basic and further layers 1, 3, 5, 7, 9 of a reflecting system. Because of high thermal resistivity, the scattering layer 2 can be applied for covering X-ray tubes.
• the scattering layer 2 is arranged either on the surface of the structure directed to the source of radiation R or in its depth, between two layers 1, 3, 5, 7, 9 of a reflecting system.
• the outer surface of the structure can be made with a covering layer 4 consisted of any material of required characteristics, e.g. of 24 Cr which is advantageous because of excellent heat and light reflecting features, high corrosion resistivity, etc.
• the basic and further layers 1, 3, 5, 7, 9 of reflecting capability are arranged in a sequence following that of the atomic numbers, because this is very advantageous with regard to the absorption processes: the characteristic radiation is absorbed in the adjacent metal layer.
• the radiation scattered and backscattered by the basic and further layers 1, 3, 5, 7, 9 is also intensively absorbed by the structure if the basic layer 1 is arranged in the middle part and the second and further layers 3, 5, 7, 9 constitute in both directions a symmetric system.
• the other and preferred possibility is to arrange the basic layer 1 consisted of the first metal in the FCC or BCC group (see Table 1.) or of 73 Ta as first to receive the primary radiation.
• the structure from at least three metals, e.g. in the following arrangements given only by way of example and, for the sake of simplicity, without the atomic numbers: Pb , Ag , Al , Al , Ag , Pb , Ag , Al
• the scattering layer 2 is generally applied between the source of the radiation R and the basic and further layers 1, 3, 5, 7, 9 of the reflecting system, it consists of iron and the additives mentioned above.
• the normal contaminating elements of iron, as silicon or carbon, etc. are always present, they can not be exluded.
• the structure of the invention preferably consists of thirty-two layers, consisting of two- and three-component subsystems. The examples of the last are given above. Some examples of the two-components systems:
• a high heat and corrosion resistance layer made of e.g. 24 Cr between the two- and more- -layer subsystems.
• the basic and further layers 1, 3, 5, 7, 9 of the structure proposed by the invention have thickness in the range from 0.0001 to 0.002 mm, however, the lower and higher values in the range from 0.0001 to 0.01 mm or more may be also selected, if required.
• the scattering layer 2 can be thicker than the basic and further layers 1, 3, 5, 7, 9, but generally it should be not thicker than the reflecting system built-up with the basic and further layers 1, 3, 5, 7, 9.
• the structure realized according to the present inven tion results in remarkable improvement of the quality of radiographs, i.e. pictures registered by the radiologic means. It can simultaneously constitute a high effectivity shield securing protection against X-ray and gamma radiation showing high resistivity against chemical substances and thermal effects.
• the shield can be produced in form of plate-like elements of high elasticity, too.
• the layers can generally be made by known techniques of preparing thin layers, e.g. by vapour deposition, however, the thicker layers can be prepared by rolling and united by the means of an adhesive and/or the oxide layers.
• the main advantage of the proposed structure is the possibility of double use.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Analysing Materials By The Use Of Radiation (AREA)
• Particle Accelerators (AREA)

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• 1989
  • 1989-11-28 AU AU46331/89A patent/AU4633189A/en not_active Abandoned
  • 1989-11-28 BR BR898907213A patent/BR8907213A/pt unknown
  • 1989-11-28 EP EP89913115A patent/EP0400125A1/en not_active Withdrawn
  • 1989-11-28 JP JP2500059A patent/JPH03502489A/ja active Pending
  • 1989-11-28 WO PCT/HU1989/000058 patent/WO1990006582A1/en not_active Application Discontinuation
  • 1989-11-28 KR KR1019900701671A patent/KR900702537A/ko not_active Application Discontinuation

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