Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
  • H01J47/02—Ionisation chambers

Definitions

• the present invention relates to an ionizing radiation detector and a method of manufacturing this detector.
• the invention is particularly applicable to the detection of X-rays, gamma photons, protons and neutrons.
• the invention applies, for example, to the following fields: - rapid non-destructive testing with very high spatial resolution, positioning of patients in radiotherapy, with a precision greater than that which allow detectors of the prior art, which allows the decrease in doses absorbed by patients,
• detectors In the field of particle physics, which is totally different from the fields mentioned above, in particular from the field of radiography, heterogeneous detectors are known. called “calorimeters” which include a stack of metallic sheets alternating with scintillating plastic elements, connected for example to photodiodes or photomultipliers or to a light intensification tube.
• detectors are used not to provide the image of an object but to reconstruct the shape of the trajectory of each incident particle which penetrates laterally into such a detector, that is to say perpendicular to the fibers thereof, and not from the front, that is to say parallel to these fibers.
• Ionizing radiation detectors are also known, intended to exploit the image of an object, which is transported by such radiation.
• Ionizing radiation detectors comprising a metal blade which is made of a material with an effective cross-section.
• a metal with an atomic number at least equal to 73 is used for the detection of X or ⁇ photons and a metal with a very low atomic number, generally less than 14, for the detection of neutrons and other materials, such as gadolinium, being also usable for the detection of neutrons.
• This metal strip is immersed in an ionizable gas mixture which is crossed by electrically conductive wires, widely spaced from each other, thus constituting a wire chamber.
• the electrons torn from the gas molecules under the effect of this ionization are collected using an electric field and thus rendered detectable thanks to the avalanche which occurs in a thin layer of gas surrounding the detector wires.
• the detector must be used in counting mode, which limits the dose rate acceptable by this detector and requires the use of a continuous source of X-rays, comprising for example an electrostatic accelerator which is less compact than current LINAC, with waves. high frequency, and therefore requires more expensive radiological protection: it is necessary to use several cubic meters of concrete for this protection.
• a continuous source of X-rays comprising for example an electrostatic accelerator which is less compact than current LINAC, with waves. high frequency, and therefore requires more expensive radiological protection: it is necessary to use several cubic meters of concrete for this protection.
• the avalanche mentioned above takes place around the widely spaced wires of the chamber, which degrades the spatial resolution of the detector.
• the spatial resolution in a direction parallel to an edge of the metal plate is fundamentally limited by the phenomenon of parallax, due to the propagation of primary photoelectrons in the thickness of gas located between the blade and wires, thickness which allows the creation of a sufficient number of ionizations in the gas in order to count by avalanche the particles detected (for example X photons or neutrons).
• the resolution of such a detector is further limited by the distance, of the order of a few centimeters, between the wires which it comprises.
• the maximum dose rate that this detector allows is low due to the large distance between the wires and the detector cathode, which prevents the rapid elimination of the space charge due to the positive ions which accumulate. in the son's room.
• the object of the present invention is to remedy the above drawbacks. It proposes a detector of ionizing radiation which is capable of reading the image of an object, transported by this radiation, more easily than the known detectors, mentioned above.
• the invention provides a detector which is superior to the radiographic films mentioned above because this detector makes it possible to obtain a digital image, instantly available and of better quality than the images obtained with these films, this detector being less sensitive. to scattered radiation while having a resolution at least as good as these films.
• the invention overcomes the drawbacks of detectors which use a wire chamber for the following reasons: the stopping power with respect to first ionizing particles can be much higher, up to 1000 times higher at high energy (photons of energy greater than 10 keV).
• the subject of the present invention is a detector of incident ionizing radiation consisting of first particles, this detector being characterized in that it comprises at least one elementary detector, or elementary detection sub-assembly, comprising:
• these conversion means comprising at least a first blade made of a first solid material, capable of converting the first particles into the second particles, this first blade being oriented so that the incident ionizing radiation arrives on a first edge of this first blade and along this first edge, the depth of this first blade, counted from the first edge to a second edge of the first blade, opposite to the first edge, being at less equal to a tenth of the mean free path of the first particles in the first material,
• the first material is electrically conductive and the conversion means comprise a set of first blades which is provided with microperforations, these first blades being stacked and electrically isolated from each other, and the detector further comprises polarization means provided for bringing these first blades to electrical potentials which grow from one end to the other of the set of first blades and are designed to create an electric field capable of displacing the second particles towards the excitable medium.
• the first material is resistive, with a resistivity approximately equal to or greater than 10 7 ⁇ .cm
• a first face of the first strip is formed on an electrically conductive layer and the detector further comprises: - means for extracting the second particles, provided for extracting these second particles from the first blade and sending them to the excitable medium, these extraction means comprising at least one second electrically conductive blade, provided with micro-holes and formed on a second face of the first blade, opposite the first face thereof, the first and second blades having substantially the same depth and the same width, this width being counted from one end to the other of the first edge of the first blade, and - Polarization means provided for bringing the conductive layer and the second strip to different electrical potentials, creating an electric field capable of displacing the second particles towards the excitable medium.
• the extraction means comprise a plurality of second blades, which are electrically isolated from each other and form a stack provided with micro-bores, and the polarization means are provided for carrying the second blades to electrical potentials which grow from one end to the other of the set of second blades and are intended to move the second particles towards the excitable medium.
• a semiconductor material with a resistivity of approximately equal to or greater than 10 7 ⁇ .cm can be used, as the first material, as the first material, a semiconductor material with a resistivity of approximately equal to or greater than 10 7 ⁇ .cm.
• This semiconductor material can be a semiconductor composite material, comprising a host matrix, of electrically insulating or semiconductor polymer type, and guest particles of semiconductor type, which are dispersed in this host matrix.
• the excitable medium is a medium which can be ionized by the second particles, capable of generating electrical charges constituting the third particles, by interaction with these second particles, this medium ionizable having substantially the shape of a third blade which is parallel to the first blade, these first and third blades having substantially the same depth and the same width, this width being counted from one end to the other of the first edge of the first blade, the collection means comprises a plurality of strips parallel, electrically conductive and electrically insulated from one another, these strips being capable of collecting charges electric for providing 'electrical signals representative of the incident ionizing radiation, and the detector comprises in addition polarization means provided for creating an electric field capable of moving the second particles of the conversion means towards the ionizable medium and the electric charges of this. medium ionizable towards the set of parallel bands.
• This ionizable medium is preferably gaseous.
• the excitable medium is capable of generating photons constituting the third particles, by interaction with the second particles, this excitable medium having substantially the shape of a third plate which is parallel to the first blade, these first and third blades having substantially the same depth and the same width, this width being counted from one end to the other of the first edge of the first blade, and the collection means comprise guides parallel lights, suitable for collecting photons to provide light signals representative of the incident ionizing radiation.
• the width of the first blade, counted from one end to the other of the first edge of this first blade is approximately equal to or greater than 10 cm.
• the thickness of this first blade is approximately equal to or less than
• the object of the invention detector may include a plurality of stacked elementary detectors.
• the present invention also relates to a method of manufacturing the detector which is the subject of the invention, in which the conversion means are formed and these conversion means and the collection means are placed on either side of the excitable medium.
• the first strip is formed on the electrically conductive layer and 1 'the second blade is fixed to the first blade.
• FIG. 1 is a schematic perspective view of a detector according to the invention which detects the image of an object, transported by ionizing radiation
• FIG. 2 is a schematic perspective view of a mode of particular embodiment of the detector object of the invention, using a resistive conversion material
• FIG. 3 is a schematic perspective view of another particular embodiment comprising several detectors of the type of that of FIG. 2, stacked one on the other,
• FIG. 4 is a schematic perspective view of another particular embodiment, using an electrically conductive conversion material
• FIG. 5 is a schematic perspective view of another particular embodiment, using a gas capable of emitting light when it is excited by charged particles, while the detectors of Figures 2 to 4 use a gas ionizable.
• the detector 2 which is shown diagrammatically in FIG. 1, is intended to detect penetrating ionizing radiation 3 of high energy, for example consisting of X photons or ⁇ photons or protons or even neutrons.
• This detector converts the image transported by this radiation 3 into particles, for example electrons, whose operation is easier than that of radiation.
• a medium which can be a solid medium, for example semiconductor or photoconductive or even photovoltaic, or a gaseous medium.
• the detector then makes it possible to locally read the energy deposited by these particles to constitute an analog-like image.
• This detector 2 can for example associate this detector 2 with a source 4 of ionizing radiation, this source being almost point-like.
• This detector 2 which has a planar shape, substantially parallelepipedic, is a stack of layers, or blades, the structure of which will be given in the description of Figure 2.
• the input face of the detector is arranged in a direction x which is perpendicular to the direction z.
• the beam 8 is arranged between the source 4 and the object 6 and provided so that the beam of the radiation 3, which reaches the object 6 then the detector, is substantially plane and parallel to the plane xz.
• the width of the detector is counted in the direction x. This width can be very large. It can exceed 1 meter.
• the detector 2 has a great depth which is counted in the direction z. This depth is greater than one tenth of the average free path of the radiation in the material that the detector comprises and which is intended to convert the image transported by the ionizing radiation, in order to ensure a high stopping power with respect to this radiation.
• This material which will be discussed in more detail later, can be chosen so as to have a stopping power greater than 50%.
• a very large number of detection pixels are formed which are aligned in the direction x (direction of the width of the detector).
• the distance between two adjacent pixels can be very small, for example equal to 100 ⁇ m, which ensures the spatial resolution of the radiographic image in the x direction.
• Detector 2 is a linear detector. It can be provided with a scanning function in order to carry out a scanner function making it possible ultimately to obtain a two-dimensional image (such as an X-ray film). To obtain this sweep, it is for example possible to mount the bar arranged horizontally on a jack which moves it vertically.
• the thickness of the material allowing the conversion of the incident ionizing radiation (material to which we will return later) is likely to be very small. This thickness is counted in a direction y which is perpendicular to the directions x and z. This direction is called "scanning direction”.
• the low thickness of the conversion material guarantees the spatial resolution of the radiographic image in the y direction which is parallel to the scanning.
• the closely spaced pixels provide resolution in the x direction.
• the weakness of this thickness reduces the sensitivity of the detector to parasitic radiation, the pulse vector of which no longer passes through the source 4 as a result of the scattering of the radiation in the various media encountered or crossed.
• FIG. 2 is a schematic perspective view of the detector 2.
• this detector is intended for the detection of X-rays. It comprises a substantially parallelepiped blade made of a material intended to convert the X-rays electron incident. This material is resistive, with a resistivity of approximately 10 7 ⁇ .cm or greater than this value.
• the width, depth and thickness of the blade 10 are noted respectively L, P and E.
• the depth P of this blade 10 is counted along the axis z parallel to the direction of the incident radiation 3. Its width is counted according to the direction x perpendicular to the direction z and its thickness E is counted along the direction y which is perpendicular to the directions x and z.
• An edge 12 of blade 10 is the detector input face 2. This edge 12 is perpendicular to the z-direction and parallel to the 'x direction. the blade 10 is parallel to the plane defined by the directions x and z and oriented so that its edge 12 receives the radiation beam 3 substantially plane (which is also parallel to the plane xz).
• the strip 10 of resistive material is formed on an electrically conductive layer 14 constituting the cathode of the detector 2.
• This detector 2 also comprises a stack 15 of electrically conductive layers which are electrically isolated from each other.
• this stack comprises three layers of width substantially equal to L and of depth substantially equal to P, namely two conductive layers 16 and 18 between which there is an electrically insulating layer 20.
• the conductive layer 16 is formed on the face of the blade of resistive material 10, opposite that which rests on the electrically conductive layer 14.
• the stack is provided with a large number of holes 22 whose size is of the order of 10 ⁇ m to 20 ⁇ m for example and which are called "micro-holes".
• the detector of FIG. 2 is placed in a hermetically closed casing 24 which contains a gas ionizable by the electrons.
• this box is provided with means (not shown) for circulation and purification of this gas.
• This box 24 includes a window 26 which is transparent to incident ionizing radiation 3 and which is located opposite the edge 12 of the blade of resistive material 10, on which this radiation 3 arrives.
• an aluminum window or, if necessary, other materials can be used.
• the detector 2 also comprises an electrically insulating strip 28, one face of which carries electrically conductive tracks equidistant 30 and parallel to each other. This face carrying the tracks faces the conductive layer 18 of the stack.
• the insulating strip 28 is parallel to the plane xz and the conductive tracks 30 are parallel to the direction z.
• a space 31 is provided between the stack of layers 16, 18 and 20 and the insulating strip 28.
• This space of width substantially equal to L and of depth substantially equal to P, is filled with the gas contained in the housing 24 (or circulating in the latter). This gas can then be ionized by electrons capable of leaving micro-holes 22 as will be seen later.
• the detector 2 is provided with means 32 for polarizing the layers 14, 16 and 18 and the tracks 30, allowing the conductive layer 14 to be brought to a potential lower than that of the conductive layer 18, itself lower than the potential of each of the conductive tracks 30, the intermediate conductive layer 16 being brought to an intermediate potential between the respective potentials of the conductive layers 14 and 18 by connecting layers 16 and 18 via an electrical resistance R of appropriate value.
• the micro-tracks 30 are grounded, the potential of the conductive layer 18 is negative and the potential of the conductive layer 14 is even more negative.
• the radiation 3 interacts with the material of the blade 10. Electrons are thus generated in this material. Given the potentials chosen, these electrons are extracted from the material of the blade thanks to the stack of layers 16 to 18 and pass through the micro-holes 22 of the latter.
• These electrons then interact with the ionizable gas contained in the space between the stack and the tracks 30, which creates other electrons and, if necessary, avalanches of these other electrons (the gain from 1 to 10 5 being adjustable).
• the electrons generated in the ionizable gas are then collected by the conductive tracks 30.
• the latter have a very small width, for example of the order of 1 ⁇ m, and thus constitute microtracks. In addition, they are very close from each other: they are for example spaced 100 ⁇ m from each other.
• these microtracks 30 supply signals which are detected by means of appropriate electronic processing means 34 or reading circuit.
• each micro-track 30 there is, for each micro-track 30, a capacitor 36 and a fast operational amplifier 38.
• Each capacitor 36 is connected, on one side, to the corresponding micro-track 30 and , on the other hand, to the corresponding operational amplifier 38.
• microperforations or slits serve to compress the electrostatic field lines which start from the conductive layer 14.
• the tightening of the field lines which guide the electrons to be collected causes a localized increase in the electric field. This increase makes it possible to extract the electrons from the plate 10 and inject them into the ionizable gas.
• a physical amplification is useful to compensate for the small number of ionization charges generated by the primary photoelectrons when they pass through the thin thickness (for example 100 ⁇ m) of the plate 10.
• This small thickness makes it possible to avoid the parallax problems which degrade the spatial resolution of the detector in the x direction because the photoelectrons make a certain angle with the direction of the radiation to be detected. In addition, this small thickness allows the use of an inexpensive reading circuit 34.
• the detector according to the invention which is shown diagrammatically in perspective in FIG. 3, is a detector of the matrix type.
• This detector of FIG. 3 is a stack of detectors of the kind of that of FIG. 2. In the example of FIG. 3, three detectors of this kind are used. More precisely, the detector of the figure
• This detector of FIG. 3 is also placed in a box 40 containing the ionizable gas and provided with an inlet window 42 transparent to the radiation to be detected, for example an X-ray which has the reference 44 in FIG. 3.
• This detector of FIG. 3 comprises three stacked elementary detectors 46, 48 and 50. which are of the type of that of FIG. 2.
• the first elementary detector 46 comprises the conductive layer 14, the strip of resistive material 10, the stack 15 of conductive layers separated by an insulating layer and provided with microperforations 22, the space 31 containing the ionizable gas and the electrically insulating strip 28 carrying the electrically conductive microstrips 30.
• the second elementary detector 48 On this first elementary detector 46 is placed the second elementary detector 48.
• the conductive layer 14 of this second elementary detector rests on the electrically insulating plate 28 of the detector 46.
• This second detector 48 is constituted like the detector 46 and it is the same for the third elementary detector 50, the conductive layer 14 of which is formed on the electrically insulating strip 28 of the second elementary detector 48.
• a matrix of conductive micro-tracks 30 is thus obtained which is connected to suitable electronic processing means 52.
• the detector of FIG. 3 is provided with polarization means - 54 making it possible to bring each conductive layer 14 to a potential lower than the potential of the associated conductive layer 18, this potential being itself lower than the potential to which the micro-tracks are carried. associated 30, these microtracks being grounded in the example shown, the associated intermediate conductive layer 16 being further brought to an intermediate potential between the potentials of the conductive layers 14 and 18 by means of an appropriate electrical resistance R.
• spacers are provided to maintain an appropriate distance between each insulating strip, carrying the conductive micro-tracks, and the microperforated conductive layer which faces it.
• a blade of a solid ionizable material for example silicon, AsGa or ZnS at the place space 31 filled with ionizable gas.
• the blade 10 can be made of a porous semiconductor such as iodide, of cesium in the form of needles.
• a thin layer of diamond formed by chemical vapor deposition, or any other resistive semiconductor such as CdTe, ZnTe, AsGa, InP, crystalline Si or amorphous Si.
• Such a semiconductor composite material comprises an insulating or semiconductor polymer forming a host matrix in which are dispersed semiconductor particles forming guest particles.
• semiconductor polymer it is possible, for example, to use PPV (polyphenylenevinylene), polythiophene, polyaniline, polypyrrole or polydiacetylene.
• PPV polyphenylenevinylene
• polythiophene polythiophene
• polyaniline polyaniline
• polypyrrole polydiacetylene
• isooctane As an insulating polymer, isooctane can be used.
• the invited particles which are introduced into the host matrix have a high stopping power with respect to the incident radiation. They have its function is to capture this radiation and convert it into electrons.
• these invited particles should have an average atomic number, an average density and an average relative permittivity respectively greater than the average atomic number, the average density and the average relative permittivity of the polymer.
• guest particles are used having an average atomic number greater than 14, an average density greater than 2 g / cm 3 and an average relative permittivity greater than 10.
• These invited particles are preferably obtained from a semiconductor powder (for example CdTe, ZnS, ZnSe or ZnTe), the grains of which have sizes of the order of 1 nm to 100 ⁇ m, or even colloidal particles of this semiconductor.
• a semiconductor powder for example CdTe, ZnS, ZnSe or ZnTe
• a layer of composite semiconductor material can be produced in various ways.
• the polymer intended to constitute the host matrix is first dissolved in a solvent, for example toluene, then mixed with the semiconductor powder for example by means of a drum, a mixer-granulator or a granulating plate.
• a solvent for example toluene
• a simple sedimentation may even be sufficient and the excess solvent is then poured in and then the remaining solvent is allowed to evaporate.
• the homogeneous mechanically prepared mixture can be extended.
• the solvent then evaporates and leaves a composite layer which can be a few hundred micrometers thick.
• the semiconductor powder mixed with an anti-caking agent compatible with the monomer intended to form the host matrix is mixed and, by polymerizing, this monomer traps the grains of the semiconductor.
• the powder can then be recovered dry and then treated as seen above to form the layer of composite material or be entrained directly by the polymer solution (or the monomer).
• the deposition can take place on a cooled substrate capable of supporting the monomer or the polymer in solution, or by simultaneous evaporation of the organic molecules, intended to form the host matrix in polymer. It is also possible to use a technique of simultaneous projection of the semiconductor powder, by a gas stream, for example a stream of nitrogen, causing more or less molten semiconductor droplets, produced by means of a plasma torch, and polymers also in the form of droplets.
• a gas stream for example a stream of nitrogen, causing more or less molten semiconductor droplets, produced by means of a plasma torch, and polymers also in the form of droplets.
• a powder of a semiconductor such as Pbl 2 is used which is deposited in the vapor phase to form such a strip.
• the dimensions given above can be reduced if necessary, since pixels having a pitch of 50 ⁇ m are technically feasible.
• this set of three layers being substantially planar, and the micro-perforations 22 are formed through this set by photoengraving.
• an epitaxy is made, on the slide 10 of the conversion material, of a three-layer sheet (metal-insulator-metal), which is crossed by microperforations, this sheet being produced beforehand.
• the micro-perforations have a diameter of approximately 25 ⁇ m and are spaced from each other by 30 to 50 percent.
• micro-perforations 22 If the electric field in the micro-perforations 22 becomes large, an avalanche gain is obtained in these micro-perforations 22, which can play the role of an optional pre-amplification.
• this detector To supply this detector with electrical voltages which can go up to 500 V taking into account the fact that the electrical connections are close to each other, one can use a printed circuit formed on a ceramic.
• the blade 10 of conversion material can, for its part, be produced according to any suitable method.
• the underside of this blade 10 is coated with a metal layer forming the layer 14 and capable of creating ohmic contact with the blade 10 of conversion material.
• a metal layer forming the layer 14 and capable of creating ohmic contact with the blade 10 of conversion material.
• a layer of gold is used.
• CVD chemical vapor deposition
• a sheet with three layers of metal-plastic-metal is fixed, for example with a conductive adhesive, to the blade of conversion material thus obtained, which is micro-perforated, for example by chemical attack.
• a plastic material of the Kapton (registered trademark) type is used to form the intermediate insulating layer 20.
• An electrically insulating plate 28 is provided, using electrically insulating means, to the assembly thus obtained, provided with conductive tracks 30 typically spaced 100 ⁇ m apart, while providing a predefined thickness of ionizable gas to obtain an avalanche phenomenon, thanks to electrically insulating cylindrical studs and by using electrically insulating spacers (for example forming balls, filaments, a honeycomb structure or a highly cellular foam).
• electrically insulating spacers for example forming balls, filaments, a honeycomb structure or a highly cellular foam.
• micro-tracks 30 protrude a few micrometers from the insulating plate 28 to cover an edge of this plate, in order to allow an electrical connection to the reading circuit 30.
• This reading circuit can be an ASIC or integrated circuit specific to an application (“application specifies integrated circuit”) of the kind of CCD reading chips which are for example marketed by the company EG & G RETICON or THOMSON.
• An electric field of the order of 1000 V / mm to 5000 V / mm can be established between the upper face of the assembly 15 of three layers and the plane of the conductive micro-tracks 30 to create an electric field conducive to amplification by avalanche and to collect electrons.
• the micro-tracks are connected to the legs of the integrated reading circuit, for example, by a bond (“bonding”) by means of solder balls.
• solder balls or wires or by pressure (or soldering) or by gluing with an electrically conductive glue.
• a connector can be used to match the pitch of the tracks to that of the legs of the reading chip (ASIC).
• connection comprising a flexible part which makes it possible to separate the ASIC circuit from the collimated flux of X-ray.
• the thickness and the width of the plate 10 are chosen so as to optimize the spatial resolution of the detector 2 as well as the conversion efficiency in this detector.
• the detector according to the invention differs from the detector 2 in FIG. 2 in that the assembly formed by the strip of resistive material 12, the conductive layer 14 and the set of the three layers 16, 18 and 20 of this detector 2 is replaced by a stack 55 of layers of an electrically conductive material, capable of converting the incident X-radiation into electrons, these layers being spaced from each other by electrically layers insulating for example in oxide of this same metal (anodization).
• the assembly formed by the strip of resistive material 12 the conductive layer 14 and the set of the three layers 16, 18 and 20 of this detector 2 is replaced by a stack 55 of layers of an electrically conductive material, capable of converting the incident X-radiation into electrons, these layers being spaced from each other by electrically layers insulating for example in oxide of this same metal (anodization).
• the layer 58 is that which is located opposite the microtracks 30.
• Polarization means 64 are used to bring the conductive layer 56 to a potential lower than the potential of the conductive layer 58, itself lower than the potential of the micro-tracks 30.
• these micro-tracks are grounded and the conductive layer 57 is brought to a potential intermediate between the respective potentials of the conductive layers 56 and 58.
• the conductive layer 57 is respectively connected to the layers conductive 56 and 58 by appropriate electrical resistors R x and R 2 .
• the X-rays incident on the edge 66 of the stack 55 still generate, by interacting with the material of the layers 56, 57 and 58, electrons which pass through the micro-holes 62 and ionize the gas comprised between the conductive layer 58 and the electrically insulating blade 28 carrying the micro-tracks 30.
• the electrons generated in the ionized gas are still detected by these micro-tracks and the latter provide electrical signals which are read by the electronic processing means 34.
• microperforations 62 It is specified that the microperforations 62
• Two or more than two detectors of the type of that of FIG. 4 can be stacked (placed in the same housing) to obtain a matrix detector of the type of the detector of FIG. 3.
• the detector according to the invention which is shown diagrammatically in perspective in FIG. 5, differs from the detector in FIG. 2 in that the blade 28 carrying the micro-tracks 30 is omitted.
• the space 31 is delimited by the stack 15 and an electrically conductive strip 67 which is parallel to the plane xz and grounded.
• the ionizable gas of FIG. 2 is replaced by a gas, for example a gas mixture argon / dimethylether / triethylamine, which is capable of emitting light by interaction with the electrons emerging from micro-holes 22 of the assembly 15.
• a gas for example a gas mixture argon / dimethylether / triethylamine, which is capable of emitting light by interaction with the electrons emerging from micro-holes 22 of the assembly 15.
• ends of optical fibers 68 are placed which are equidistant and parallel to each other and to the direction z of the X-ray that we want to detect.
• optical fibers are connected to an electronic camera 70, for example of the CCD or CID type, or to a camera comprising an amorphous silicon matrix.
• the light emissions from the gas contained in the space 31 are picked up by the optical fibers 68 and constitute an image, in analog form, of the image transported by the radiation to be detected 3.
• electrical insulation means are provided, for example an electrically insulating layer, between two adjacent detectors without which there would be contact between a layer 14 and an adjacent blade 67.
• detectors in accordance with the invention can be obtained by replacing the assembly formed by layer 14, blade 10 and stack 15 of the FIG. 5 by the stack 55 of FIG. 4. These other detectors can be stacked (in the same case) to form a matrix detector.
• the invention is not limited to the detection of X or ⁇ photons: it applies for example to the detection of neutrons by using a plastic blade to interact with these neutrons by then providing protons.

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