Ionising radiation detector

Abstract

The invention relates to an ionising radiation detector, the detector comprising a scintillator, a monomer and a catalyst, wherein: - the scintillator emits non-ionising radiation after absorbing ionising radiation, - the catalyst catalyses the polymerisation of the monomer after absorbing the non-ionising radiation emitted by the scintillator, - the polymer resulting from the polymerisation of the monomer has a different colour from the monomer.

Description

[0001] DESCRIPTION

[0002] TITLE: Ionizing Radiation Detector

[0003] TECHNICAL FIELD

[0004] The invention relates to a method for detecting and a detector of ionizing radiation as well as to a method for manufacturing such a detector.

[0005] STATE OF THE ART

[0006] As part of any industrial activity carried out under ionizing radiation, particularly in nuclear power plants in operation or being decommissioned, checks and maintenance of the various equipment are scheduled. The main risks for workers carrying out these operations are contamination and irradiation. Irradiation corresponds to the case where the worker is exposed from the outside to radiation emitted by emitting particles far from the worker. Contamination corresponds to the case where the worker has come into direct contact with the particles emitting ionizing radiation: either by inhalation or ingestion (this is internal contamination), or by direct contact with the skin (this is external contamination). If irradiation stops when the worker is no longer exposed to the radiation source, this is not the case for contamination.A source of irradiation and contamination of workers is, for example, radioactive material which is disseminated in the air and on the surfaces (floor, pipes, etc.) of the premises where said workers are working during a leak in the circuits and which contaminates said premises.

[0007] It is necessary, in each room, to measure the surface activity of radioactive particles possibly disseminated in the air and on surfaces in order to define the types of collective protection (containment airlocks, etc.) and individual protection (ventilated waterproof suit, etc.) necessary to limit the exposure of operators to ionizing radiation emitted by radioactive particles, or radionuclides, and to prevent them from contaminating themselves, whether by internal or external contamination. The activity of a radionuclide is the number of entities of said radionuclide which disintegrate per second, expressed in becquerels (Bq). The surface activity is the activity of the radionuclides present on a surface divided by the value of the area of ​​said surface and is expressed in becquerels per square centimeter (Bq / cm 2 ).

[0008] The measurement of surface activity, particularly for alpha radiation emitters (a particle consisting of two protons and two neutrons) and beta radiation emitters (electrons or positrons), is complicated to implement for reasons related to the nature of the particles emitted and the physics of their interaction with matter. Thus, alpha particles, due to their mass and high charge, interact with matter through Coulomb interaction by ionizing and exciting atoms and molecules. They are very weakly penetrating but highly ionizing and the most dangerous in case of ingestion or inhalation. Beta particles also interact with matter through Coulomb interactions by ionizing atoms and molecules. These particles are more penetrating but less ionizing than alpha particles.

[0009] The means commonly used in nuclear power plants for detecting radioactive particles contaminating a room are devices called contaminameters. Contamination meters measure a surface activity value (in Bq / cm 2 ) or counting (cps, counts per second), but they do not allow direct visualization of contamination.

[0010] There are several ways to use a contamination meter. Direct measurement involves taking the measurement directly on the surface suspected of being contaminated by particles emitting ionizing radiation, keeping the contamination meter as close as possible to the surface (between a few millimeters and 5 cm depending on the nature of the contamination). If the surface to be tested is large, it is also possible to scan the surface with the contamination meter, for example at a speed close to 5 cm / s. Indirect measurement involves taking a smear sample from the surface suspected of being contaminated, then transferring the smear to a room with low gamma background noise to take the measurement on the smear, keeping the closest possible distance between the contamination meter and the smear or using a smear changer (for example, type NT200).Indirect measurement is necessary in some cases, especially if the gamma background noise is significant enough to disturb direct measurements (for a gamma background noise greater than about 1 pSv / h, said gamma background noise being able to be caused for example by the elements. 60 Co, 58 Co, 110 Ag and by a lot of radiation scattered by surfaces, pipes, etc.).

[0011] Such direct or indirect measurements with a contamination meter have several disadvantages. During a direct measurement or screening, as previously mentioned, it is particularly necessary to bring the probe used as close as possible to the surface to be measured. Indeed, a very short distance (a few centimeters to tens of centimeters) in the air is sufficient to stop alpha and beta particles. The detection efficiency therefore decreases rapidly with the distance between the probe and the surface to be measured. Such near-contact measurements require the operator to remain close to the potentially contaminated area, thus exposing him to an increased risk of internal and / or external contamination.Furthermore, screening, due to a limited scanning speed, can be time-consuming, particularly if the surface to be checked is large or has a complex and / or non-flat geometry, which leads to prolonged exposure of the workers carrying out the measurements to the potentially contaminated environment and therefore increases the risk of contamination of said workers. Indirect measurement, for its part, leads to additional working time in a potentially contaminated irradiating area as well as additional dressing / undressing steps and, therefore, an increased risk of dissemination of contamination and / or contamination of the operator. Finally, measurements by contamination meter, whether direct or indirect, give the value of the surface activity at the time of measurement or sampling.They are not visual and to know the temporal evolution of the contamination, it is necessary to repeat the measurement several times, with the associated risks.

[0012] Other solutions are proposed to be able to visualize the contamination in a room. For example, the "alpha-camera" can be used to detect alpha particles. The detection of said alpha particles is carried out indirectly by measuring the radioluminescence emitted by the nitrogen molecules in the air following the ionization of said molecules by the alpha radiation to be detected. Thus, the emission frequencies of the radioluminescence used by the alpha-camera are in the ultraviolet range, between 200 nm and 400 nm, so that an optical sensor and processing of the captured data are necessary. Access to the contamination information is therefore not directly visible to the naked eye. In addition, a power supply is necessary for the operation of the alpha-camera.Finally, the use of the alpha camera is restrictive for the user since, to avoid light pollution, measurements must be carried out in the dark (cover around the target). Thus, the applications of the alpha camera are mainly aimed at controlling contamination in glove boxes and controlling the decontamination of objects (measurements before and after decontamination).

[0013] Another solution is to use radiochromic films comprising a monomer from the diacetylene family trapped in a self-supporting neutral polymer matrix. When the film is directly exposed to ionizing radiation (X-rays, gamma, beta or alpha rays), the diacetylene monomer polymerizes. Optical density analysis of the film reveals the blackening of the radiochromic film due to the transition from the uncolored or slightly colored monomer state (pale yellow, pale blue or white) to the colored polymer state. In the medical field, the blackening of radiochromic films is used, for example, to check beam collimation for radiotherapy. The sensitivity of such radiochromic films depends on the nature of the ionizing radiation. For the detection of alpha particles, the color change of the films is only visible to the naked eye for activities of the order of a few MegaBecquerels (MBq).For example, the color change of an EBT3 film from the company Gafchromic is observed following exposure of said EBT3 film to a source of. 241 Am of 3.7 MBq. Such films are therefore not efficient enough to detect leaks of radioactive material on construction sites carried out on industrial installations where there is a risk of exposure to ionizing radiation, for example on construction sites carried out on the site of a nuclear power plant in operation or being dismantled. Indeed, the activity to be detected on these sites is generally between ten Becquerel and a few kilos Becquerel. For such low activities, the color change of said radiochromic films is not visible to the naked eye and it is actually necessary to use a scanner to be able to detect the change in color of the film. The detector response is therefore neither visual nor immediate.

[0014] BRIEF DESCRIPTION OF THE INVENTION

[0015] One aim of the invention is to design a detector of ionizing radiation, in particular alpha radiation, which allows detection with the naked eye of activities between around ten Becquerels and a few kilo Becquerels (kBq) without requiring the use of an additional reading device.

[0016] The detector must in particular be able to visually alert an operator to the presence of radioactive material contaminating a worksite carried out on a nuclear power plant site in operation or being dismantled, for example due to a leak in the circuits, or contaminating the operator himself (contamination on the skin or clothing), the activity of the contamination being between around ten Becquerels and a few kilos Becquerels. The detector must also quickly inform him of the presence of said contamination. Thus, the operator is not obliged to approach the area suspected of contamination to carry out the measurement and he is not exposed for a prolonged period to said contamination without being warned.

[0017] The detector must finally be able to operate autonomously for the entire duration of the worksite until the appearance of contamination or irradiation due to the presence of radioactive particles emitting ionizing radiation on the worksite or on the skin or clothing of those working on the worksite.

[0018] A first object of the invention therefore relates to an ionizing radiation detector, the detector comprising a scintillator, a monomer and a catalyst, in which:

[0019] - the scintillator is capable of absorbing ionizing radiation and emitting non-ionizing radiation following the absorption of ionizing radiation,

[0020] - the catalyst is capable of absorbing at least part of the non-ionizing radiation emitted by the scintillator and of catalyzing the polymerization of the monomer following the absorption of at least part of the non-ionizing radiation emitted by the scintillator, - the polymer, which results from the polymerization of the monomer, has a color different from the monomer.

[0021] According to other optional characteristics of the ionizing radiation detector taken alone or in combination where technically possible:

[0022] - the monomer and the catalyst are included in the same solid composition, said solid composition preferably being in the form of a powder, in particular a powder compacted in a layer arranged on a support;

[0023] - the solid composition is replaceable after use of the detector;

[0024] - the solid composition comprises the monomer in an ordered crystalline form, the catalyst being incorporated into the crystal of the monomer;

[0025] - the solid composition does not include a polymer binder or additives;

[0026] - the scintillator is not included in the solid composition;

[0027] - the scintillator is included in a scintillating solid layer arranged on the solid layer composition comprising the monomer and the catalyst;

[0028] - the scintillator is included in a scintillating liquid, the solid composition being insoluble in said scintillating liquid;

[0029] - the detector further comprises a filtering film arranged so as to filter ultraviolet radiation external to said detector;

[0030] - the monomer is a diacetylenic monomer of the following formula (I):

[0031] R1-C=CC=C-R2 (I) wherein R1 and R2 are independently selected from an optionally substituted C1-C18 hydrocarbon chain, an optionally substituted aryl group and an optionally substituted heteroaryl group, wherein one or more, preferably 1 to 4 methylene groups of said hydrocarbon chain are optionally replaced by O, C(O), NH or N-(C1-C6alkyl);

[0032] - the monomer is capable of absorbing at least part of the non-ionizing radiation emitted by the scintillator;

[0033] - the monomer is not capable of absorbing at least one wavelength at which the catalyst is capable of absorbing non-ionizing radiation and / or the catalyst is not capable of absorbing at least one wavelength at which the monomer is capable of absorbing non-ionizing radiation from the scintillator;

[0034] - the scintillator comprises barium fluoride BaF2 and / or the catalyst is chosen from quinones and benzophenones.

[0035] The invention also relates to a method for detecting ionizing radiation comprising the following steps:

[0036] EO) Provision of a detector as previously described, E1) Emission by the scintillator of non-ionizing radiation following absorption of ionizing radiation,

[0037] E2) Polymerization of the monomer, the polymerization being catalyzed by the catalyst, following absorption by the catalyst of at least part of the non-ionizing radiation emitted by the scintillator, the resulting polymer having a color different from the monomer, E3) Observation with the naked eye of the color change.

[0038] Finally, the invention relates to a method of manufacturing an ionizing radiation detector comprising the following steps:

[0039] - provide a scintillator capable of absorbing ionizing radiation and emitting non-ionizing radiation following absorption of the ionizing radiation,

[0040] - arranging a monomer relative to the scintillator so that the device changes color when the monomer polymerizes, the resulting polymer having a different color from the monomer,

[0041] - arranging a catalyst with respect to the monomer and the scintillator, the catalyst being capable of absorbing at least a portion of the non-ionizing radiation emitted by the scintillator and of catalyzing the polymerization following the absorption of the at least a portion of the non-ionizing radiation emitted by the scintillator.

[0042] BRIEF DESCRIPTION OF THE FIGURES

[0043] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0044] - Figure 1 represents a detector of ionizing radiation emitted by contamination according to an embodiment of the invention in which the monomer and the catalyst are included in a solid layer composition arranged on a support, the solid layer composition forming the active layer of the detector, the solid layer composition further comprising the scintillator,

[0045] - Figure 2 represents a detector of ionizing radiation emitted by contamination according to an embodiment of the invention in which the monomer and the catalyst are included in a solid layer composition arranged on a support, the solid layer composition forming the active layer of the detector, and in which the scintillator is included in a separate scintillating solid layer arranged on the active layer,

[0046] - Figure 3 represents a detector of ionizing radiation emitted by contamination according to an embodiment of the invention in which the monomer and the catalyst are included in a solid layer composition arranged on a support, the solid layer composition forming the active layer of the detector, and in which the scintillator is included in a scintillating liquid, the active layer being immersed in said scintillating liquid. For reasons of readability, the drawings are not necessarily made to scale.

[0047] DETAILED DESCRIPTION OF EMBODIMENTS

[0048] Definitions

[0049] In the following, the term ionizing radiation refers to radiation with an energy level high enough to cause atoms to lose electrons and ionize directly or indirectly. Ionizing radiation can be in the form of particles with an energy greater than 20 eV, such as alpha or beta particles. These particles, due to their mass and charge, will, when passing through matter, disrupt the electron procession of the atoms encountered and eject electrons from the outer layers of these atoms. This is called direct ionization. Alternatively or additionally, ionizing radiation can be in the form of electromagnetic waves such as gamma rays and / or X-rays. The absorption of X-rays and gamma rays by certain atoms causes the ejection of the inner electrons of these atoms. The ejected electrons, having a non-zero mass and charge, will then ionize other atoms.This is called indirect ionization. These high-energy particles and electromagnetic waves are released from radioactive atomic nuclei, which then disintegrate.

[0050] Alpha radiation is a particle consisting of two protons and two neutrons charged 2 + also identified as a helium nucleus 4 Hey 2+ The mass of the alpha particle is 6.6 10' 27 kg and its mass energy is between 3 MeV and 9 MeV. For example, the decay reaction of 241 Am in 237 Np emits alpha radiation, the most important of which are 5.486 MeV and 5.443 MeV. As another example, the decay reactions of 226 Ra in 222 Rn then in 218 Po and of 238 U in 234 Th also emit alpha radiation.

[0051] Beta radiation is defined as a particle consisting of a positive charge or a negative charge with a mass of 9.1 10' 31 kg also identified as a positron or an electron respectively. The energy of the beta particle is between zero and the maximum energy allowed by the beta decay reaction that causes the emission. For example, the decay reactions of 60 Co in 60 Neither, of 3 H in 3 He and of 14 C in 14 N emit beta radiation.

[0052] Gamma radiation is understood as electromagnetic radiation with a wavelength between 10' 14 m to 10' 12 m. Gamma rays are usually emitted during the de-excitation of an atomic nucleus resulting from a decay. For example, the beta decay reaction of 60 Co in 60Ni generates a first gamma radiation at 1.17 MeV and a second gamma radiation at 1.33 MeV. The beta decay reaction of 137 Cs in 137 Ba generates gamma radiation at 661 keV. As another example, the alpha decay reaction of 241 Am in 239 Nb generates gamma radiation at 60 keV.

[0053] X-rays are understood as electromagnetic radiation with a wavelength between 10' 8 m and 10' 11 m. X-rays are emitted during the rearrangement of the electron shells of an atom following the ejection of an electron from an inner electron shell, for example by collision with a target electron or interaction with gamma radiation. More precisely, during this rearrangement, an electron from an outer electron shell fills the inner vacancy, releasing energy in the X-ray range.

[0054] The term scintillator is understood as a molecule emitting non-ionizing radiation following the absorption of at least one type of ionizing radiation (X, gamma, alpha, beta). For example, said ionizing radiation is ultraviolet radiation (wavelength between 100 nm and 400 nm).

[0055] The term catalyst is understood as a molecule capable of increasing the kinetics of a chemical reaction, said catalyst being able to be regenerated or not at the end of the reaction.

[0056] The term contamination refers to the presence of radioactive substances - in other words, substances emitting ionizing radiation - on any surface of a biological nature (for example, skin or hair) or non-biological nature (for example, walls or objects in a room, tools or clothing of workers) or in solids, liquids or gases where their presence is involuntary and / or undesirable.

[0057] Ionizing radiation detector

[0058] The invention relates to a detector of ionizing radiation, for example ionizing radiation emitted by radioactive substances disseminated in a room, or on the skin, hair or clothing of a human being. Preferably, the invention relates to an alpha particle detector.

[0059] Location of detector use

[0060] The detector according to the invention can be used in any industrial installation in which ionizing radiation is likely to be emitted or contamination emitting ionizing radiation is likely to be disseminated, in order to detect said contamination or said radiation and thus protect the workers in said industrial application with the appropriate level of protection. The detector according to the invention is of particular interest in nuclear power plants in operation or being decommissioned where the risk of encountering this type of contamination is significant. The detector according to the invention can also be used in biology or in irradiation tests.

[0061] For example, the detector according to the invention can be formulated in solid form as a coating (e.g. gel), film, strip, pellet, flexible collars or in liquid form. The size and shape of the detector can be adapted according to the geometry of the object or surface to be checked. The coating or strip advantageously allows contamination to be detected over large areas. The pellet can advantageously be positioned in a location that is difficult to access to make a smear.

[0062] In solid form, the detector can be placed directly on construction sites, in premises likely to be contaminated or exposed to ionizing radiation, for example on the walls of contamination containment airlocks, pipes, valves, taps, etc. which are areas where early detection of contamination is necessary. It can be placed on tools (hammers, screwdrivers, etc.) or complex-shaped construction equipment which is time-consuming to check with a contamination meter (for example, scaffolding). The detector can also be placed on the clothing of construction site operators to identify which ones are contaminated and thus avoid external or internal contamination of the worker. The detector can also participate in the analysis of the transfer of contamination onto workers' clothing during the undressing phase.

[0063] Typically, radioactive particles emitting alpha or beta radiation will be detected by the detector if the detector is positioned at a maximum of about 5 cm from said particles and gamma radiation can be detected up to a few meters from their source. These characteristics make it possible in particular to determine the number and location of the most suitable detectors for the site.

[0064] Alternatively, where the detector includes at least one liquid element, the detector can be used off-site to analyse a smear (sample taken by rubbing on a surface suspected of being contaminated) during indirect measurements.

[0065] General principle of ionizing radiation detection by detector When the catalyst "catalyzes" the polymerization of the monomer, we mean that it initiates and accelerates the polymerization reaction of the monomer.

[0066] When the detector according to the invention is exposed to ionizing radiation, the scintillator absorbs said ionizing radiation and re-emits non-ionizing radiation. The monomer, the catalyst and the scintillator included in the detector according to the invention are specifically chosen so that the emission spectrum of the scintillator at least partially overlaps the absorption spectrum of the catalyst, this overlap making it possible to excite the catalyst and thus initiate the polymerization of the monomer. The absorption of said non-ionizing radiation by the catalyst in fact induces the formation of sites initiating the polymerization of the monomer, thus initiating the polymerization and therefore the change in color of the detector, thereby signaling to an operator the presence of contamination emitting ionizing radiation.

[0067] Preferably, the emission spectrum of the scintillator at least partially overlaps the absorption spectrum of the catalyst and the absorption spectrum of the monomer. Thus, in this embodiment, in addition to being catalyzed by the catalyst, the polymerization is also initiated by the absorption by the monomer of at least a portion of the non-ionizing radiation emitted by the scintillator. This results in faster and more efficient polymerization, and therefore a color change (i.e. a higher polymerization rate).

[0068] The scintillator typically absorbs a greater proportion of the energy of the incident ionizing radiation than the monomer and catalyst would if they were directly exposed to said ionizing radiation. Indeed, the scintillator re-emits energy specifically in a range of wavelengths at which the catalyst, and possibly the monomer, absorbs, so that the energy transfer between the scintillator on the one hand and the catalyst, preferably the catalyst-monomer combination, on the other hand is carried out correctly. Thus, exposure to ionizing radiation via the scintillator is generally more efficient than direct exposure of the catalyst, preferably the catalyst-monomer combination, to said ionizing radiation. In other words, for the same energy of incident ionizing radiation, a greater proportion of said incident ionizing radiation is transmitted to the catalyst, preferably to the catalyst-monomer combination.

[0069] In the presence of the catalyst generating polymerization initiator sites, the detector response time and the minimum absorbed dose required to cause a color change observable to the naked eye are reduced, including for alpha radiation. Reading the result then does not require an additional reading device, the result is given directly without correction or interpretation and can be observed remotely. The device is a passive device requiring no external power supply and can therefore be set up from the start of the worksite and which informs the operator of the appearance of contamination quickly without repeated measurements or operator interventions to recharge the device.

[0070] The detection of ionizing radiation is therefore based on the change in color of the detector. A color change is understood to mean a change in color visible to the naked eye, i.e., one that the eye can detect directly, without the use of other measuring devices. The detector, particularly in its solid form, can be placed by the operator near the area of ​​the construction site that the said operator wishes to monitor. During the intervention, the visual inspection of the detector allows the operator to remotely and continuously monitor the radiological state of the construction site (corresponding to the absence or presence of contamination). When contamination occurs, the operator can see it with the naked eye by the change in color of the detector: he can initiate the decontamination of the equipment concerned, or modify the collective and individual protections put in place on the basis of theoretical studies of site preparation.

[0071] The detector comprises a scintillator which, following absorption of ionizing radiation by said scintillator in the presence of contamination emitting said radiation, emits non-ionizing radiation in a given wavelength band. For example, the scintillator emits non-ionizing radiation in the near visible and / or ultraviolet ranges. For example, the scintillator emits non-ionizing radiation between 200 nm and 500 nm.

[0072] The detector according to the invention further comprises a monomer whose polymerization is initiated by the catalyst following the absorption by the latter of at least a portion of the non-ionizing radiation. Advantageously, the polymerization is also initiated by the absorption by the monomer at at least one given wavelength band of the non-ionizing radiation emitted by the scintillator.

[0073] The monomer used in the detector according to the invention is characterized in that its polymerization causes a change or appearance of color between the monomer state and the polymer state. Thus, if the monomer is colored, the polymer is of another color, so that the presence of ionizing radiation is deduced from the detector by a change in color of the detector. Alternatively, if the monomer is not colored, the polymer is colored and the detection of ionizing radiation by the detector of the invention is based on the appearance of a coloring. According to a variant of the detector according to the invention, the color of the polymer varies with the polymerization rate, said polymerization rate being related to the absorbed dose, so that the detector can also give a quantitative value of the energy or dose (energy per kilogram of material exposed to the radiation) absorbed.

[0074] The detector comprises a catalyst which catalyzes the polymerization reaction of the monomer following absorption by said catalyst of non-ionizing radiation at at least one wavelength at which the scintillator emits. For example, the absorption of at least a portion of the non-ionizing radiation by the catalyst causes a homolytic breakage of a bond in said catalyst, thus generating highly reactive free radicals at the origin of a radical chain polymerization, which corresponds to type I catalysis. For example, the absorption of non-ionizing radiation by the catalyst causes said catalyst to pass into an excited state, the catalyst in the excited state then interacting with another molecule called a co-catalyst, thus generating free radicals, which corresponds to type II catalysis. The co-catalyst may be chosen from amines and benzophenones.For example, the co-catalyst is selected from triethylamine, methyldiethanolamine and / or 4,4'-bis(dimethylamino)benzophenone.

[0075] The formation of polymerization initiator sites from the catalyst and possibly from the monomer following the absorption of non-ionizing radiation emitted by the scintillator constitutes the kinetically determining step of the polymerization reaction.

[0076] When the monomer does not absorb the non-ionizing radiation emitted by the scintillator, for example because the emission spectrum of the scintillator and the absorption spectrum of the monomer are disjoint, the presence of the catalyst makes it possible to initiate the polymerization reaction. In other words, in the particular embodiment where the monomer does not absorb the non-ionizing radiation of the scintillator, the detection of the non-ionizing radiation would not be possible without the use of the catalyst.

[0077] When the monomer absorbs the non-ionizing radiation emitted by the scintillator, said absorption also leads to the formation of polymerization initiator sites from the monomer, for example the formation of primary radicals which will then add to other monomeric units.

[0078] However, the formation of initiator sites following the absorption of non-ionizing radiation by the monomer may be inefficient, for example if the monomer absorbs little at wavelengths included in the wavelength band at which the scintillator emits (for example if the wavelength(s) of the absorption maxima(s) of the monomer are not included in the wavelength band at which the scintillator emits and / or if the molar extinction coefficient of the absorption maxima of the monomer is low) or if the excited monomer leads little to the formation of initiator sites, so that the polymerization reaction would be generally slow without the joint use of the catalyst.

[0079] In a preferred embodiment in which the monomer absorbs non-ionizing radiation emitted by the scintillator, the monomer does not absorb at at least one wavelength at which the catalyst absorbs non-ionizing radiation from the scintillator and / or the catalyst does not absorb at at least one wavelength at which the monomer absorbs non-ionizing radiation from the scintillator.

[0080] For example, the emission spectrum of the scintillator has two main bands: a first emission band which overlaps with an absorption band of the monomer but which does not overlap with the absorption spectrum of the catalyst and a second emission band which overlaps with an absorption band of the catalyst but which does not overlap with the absorption spectrum of the monomer. For example again, the absorption spectra of the catalyst and the monomer are completely distinct from each other, i.e. they do not have any common absorption wavelength. Such a variant advantageously makes it possible to extend to the maximum the absorption range by the monomer / catalyst pair of the non-ionizing radiation emitted by the scintillator for a given dose of ionizing radiation absorbed by said scintillator.

[0081] Detector sensitivity is defined as, for a source emitting ionized radiation, the minimum activity of the source from which the color change of the detector is visible to the naked eye.

[0082] The sensitivity of the detector is determined by the inventors as follows:

[0083] - the polymerization rate associated with the color change visible to the naked eye is determined by differential scanning calorimetry;

[0084] - from the said polymerization rate, the sensitivity is calculated as follows using a prior calibration.

[0085] The detector response time is defined as, for a source emitting ionizing radiation and a given activity, the time after which the change in color of the detector is visible to the naked eye.

[0086] Typically, the color change is observable with the naked eye on the detector of the invention after an exposure time of between 1 hour and 8 hours with an alpha radiation source with an activity of between 130 kBq and 330 kBq. Such sensitivity makes the detector according to the invention compatible with use on a nuclear power plant operating or dismantling site lasting a few hours or a few days.

[0087] Definition of monomer

[0088] The monomer is advantageously a monomer from the family of diacetylenic compounds. A diacetylenic compound designates a compound comprising two C=C triple bonds. The polymerization of diacetylenic monomers can result from a 1,4 addition between the C1 carbon atom of a diacetylenic unit and the C4 atom of the adjacent diacetylenic unit.

[0089] Diacetylene monomers have the advantage of not being colored or having a pale yellow, white or even slightly bluish coloration unlike their polymerized form, which is colored, so that the polymerization reaction causes a color change visible to the naked eye. In addition, the color of the polymer typically depends on the polymerization rate (ranging from light blue for low polymerization rates to dark blue, violet, dark violet, black to golden black for polymerization rates close to saturation). This correspondence between color and polymerization rate can be advantageously exploited by establishing for each type of UV, X, gamma, beta and alpha radiation, a calibration linking the polymerization rate to the energy deposited in the active layer. For example, the detector can be delivered with a color scale indicating the absorbed dose corresponding to each color.Thus, the detector provides quantitative information on the absorbed dose by simply observing the color of said detector and reading the absorbed dose associated with said color on the color scale.

[0090] In addition, diacetylenic monomers have the advantage of polymerizing in the solid state, which eliminates the need for a solvent and therefore potential problems with the leaktightness of the detector and / or the toxicity of said solvent.

[0091] For example, the monomer is a diacetylenic monomer of the following formula (I):

[0092] R 1 -C=CC=CR 2 (I) in which R 1 and R 2are independently selected from an optionally substituted C1-C18 hydrocarbon chain, an optionally substituted aryl group and an optionally substituted heteroaryl group, wherein one or more, preferably 1 to 4, methylene groups of said hydrocarbon chain are optionally replaced by O, C(O), NH or N-(C1-C18alkyl). For the purposes of the present invention, the term "C1-C18 aliphatic chain" means a saturated, linear or branched monovalent hydrocarbon chain comprising 1 to 18, in particular 1 to 12, carbon atoms. According to the invention, an aliphatic chain covers substituted or unsubstituted, linear or branched alkyl, alkenyl or alkynyl groups.

[0093] For the purposes of the present invention, the term “(C1-C6)alkyl” group means a saturated, linear or branched monovalent hydrocarbon chain, preferably comprising 1 to 6 carbon atoms. By way of example, mention may be made of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl or hexyl groups.

[0094] For the purposes of the present invention, the term “alkenyl” group means a monovalent, linear or branched hydrocarbon chain comprising at least one double bond. For example, ethenyl, propenyl, allyl, butenyl, pentenyl or hexenyl groups may be mentioned.

[0095] For the purposes of the present invention, the term “alkynyl” group means a monovalent, linear or branched hydrocarbon chain comprising at least one triple bond. Examples that may be mentioned include ethynyl, propynyl, butynyl, pentynyl or hexynyl groups.

[0096] For the purposes of the present invention, the term "aryl" means an aromatic hydrocarbon group, preferably comprising from 6 to 10 carbon atoms, and comprising one or more fused rings, such as, for example, a phenyl or naphthyl group. Advantageously, this is phenyl.

[0097] For the purposes of the present invention, the term "heteroaryl" means an aromatic group comprising 5 to 10 cyclic atoms including one or more heteroatoms, advantageously 1 to 4 and even more advantageously 1 or 2, such as, for example, sulfur, nitrogen or oxygen atoms, the other cyclic atoms being carbon atoms. Examples of heteroaryl groups are furyl, thienyl, pyrrolyl, pyridinyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, quinolyl, isoquinolyl, quinoxalyl or indyl.

[0098] By "optionally substituted" is meant, for the purposes of the present invention, that the group in question is optionally substituted by one or more, preferably 1 to 3 and in particular 1 or 2, substituents chosen from the group consisting of a halogen atom, a C1-C6 alkyl group, OH, oxo, aryl, heteroaryl, N3, CN NO2, NR a R b , COR C , CO2R d , CONR e R f , and OR g , in which R a to R g represents, independently of each other, H, C1-C6 alkyl, or aryl. Advantageously, R 1 and R 2 independently represent a C1-C18 hydrocarbon chain, optionally substituted by an aryl group, such as phenyl, or heteroaryl, such as pyridinyl, in which between 1 and 4 methylene groups are optionally replaced by O, C(O), NH or N-(C1-C18alkyl).

[0099] Preferably, the monomer of formula (I) comprises at least one hydrogen bond donor site and one hydrogen bond acceptor site.

[0100] A hydrogen bond is a non-covalent interaction between an atom carrying a lone pair and a hydrogen atom bonded to an electronegative atom (N, O or S). The hydrogen bond donor site is this electronegative atom and the hydrogen bond acceptor is the atom carrying the lone pair.

[0101] When the monomer is in crystalline form, these hydrogen bonds formed between an acceptor site of a first monomer of formula (I) and a donor site of a second monomer of formula (I) make it possible to promote a spatial arrangement of the monomer molecules relative to each other which is optimal for the topochemical polymerization to take place, in particular via a 1,4 addition between the carbon atom C1 of a diacetylenic unit and the atom C4 of the adjacent diacetylenic unit.

[0102] Thus, the monomer of formula (I) advantageously comprises one or more functions carrying hydrogen bond donor and acceptor site(s) such as the amide function of formula -NH-C(O)-, the urea function of formula -NH-C(O)-NH, the carbamate function of formula -OC(O)-NH, where the -NH- site is the donor of a first hydrogen bond and where the -C(O)- site is the acceptor of a second hydrogen bond.

[0103] In a preferred embodiment, the monomer of formula (I) comprises at least one urethane function of formula -NH-C(O)-O-Ci-Ci2 alkyl or -OC(O)-NH-Ci-Ci2 alkyl.

[0104] Thus, preferably, R 1 and R 2 independently represent a C1-C18 hydrocarbon chain, optionally substituted by an aryl group, such as phenyl, or heteroaryl, such as pyridinyl, said hydrocarbon chain being interrupted by one or more urea groups of formula -NH-C(O)O-.

[0105] More preferably, R 1 and R 2 independently represent a group of formula - (CH2)mOC(O)-NH-(CH2)n-CH3or CH2)m-NH-C(O)-O-(CH2)n-CH3, m and n each being independently an integer ranging from 0 to 9. R 1 and R 2 may be the same or different. Preferably, R 1 and R 2 are identical.

[0106] Preferably, the monomer of formula (I) is chosen from the group consisting of: in which n and m are each independently an integer ranging from 1 to 10.

[0107] More preferably, the monomer of formula (I) corresponds to the following formula (IA):

[0108] In the monomer of formula (I) in crystalline form, the spatial organization is particularly ordered, which makes the topochemical polymerization of said monomer particularly efficient. Such an organization is advantageous for obtaining high degrees of polymerization and therefore a color change easily visible to the naked eye, which makes it possible to dispense with the use of other additives such as an opacifier or a colorant in the detector. In addition, said monomer is not sensitive to the presence of oxygen, which makes it possible to dispense with the use of an antioxidant in the detector.

[0109] For example, the monomer (IA) has a pale blue color, while the polymer has a blue coloration that is darker as the degree of polymerization increases, thus making it possible to quantify the absorbed dose using a color scale.

[0110] The monomers of formula (I) according to the invention typically absorb non-ionizing radiation emitted between 200 nm and 450 nm. More precisely, the absorption spectra of the monomers of formula (I) most often exhibit two absorption bands: a main absorption band whose maximum is between 200 nm and 300 nm and a secondary absorption band whose maximum is between 300 nm and 400 nm or between 300 nm and 450 nm if the monomer of formula (I) comprises an aromatic ring. When the monomer of formula (I) is excited in its secondary absorption band, the polymerization kinetics are slow. When the monomer of formula (I) is excited in its main absorption band, the polymerization kinetics are faster. For example, monomer (IA) has a main absorption band with an absorption maximum at 254 nm and a secondary absorption band with an absorption maximum at 365 nm.The said secondary absorption band is of very low intensity, so that it is barely or not visible on the absorption spectrum of the monomer (IA), but the monomer (IA) still polymerizes when excited at a wavelength of 365 nm.

[0111] Definition of scintillator

[0112] The scintillator used in the detector according to the invention is typically selected from the group consisting of inorganic scintillators such as barium fluoride BaF2, ZnS(Ag) or CaF2(Eu), plastic scintillators such as BC400™, BC404™, BC408™, BC412™ and BC412™ from LuxiuSolutions and ceramic scintillators such as GAGG™ and GPS™ available for example from Epic-cristal, Crystro and Crylink. Advantageously, the scintillator comprises, in particular consists of, barium fluoride BaF2. Barium fluoride has the advantage of being resistant to radiation. In addition, barium fluoride is advantageously in the form of a transparent crystal.In the embodiment of the detector described below comprising a scintillator layer superimposed on an active layer comprising the monomer and the catalyst, such a transparent crystal makes it possible to observe the change in color of the active layer resulting from the polymerization of the monomer directly through said transparent crystal, without having to separate the active layer from the scintillator layer. Barium fluoride is also advantageously transparent to its own light. In other words, the absorption spectrum of barium fluoride does not overlap with the emission spectrum of said barium fluoride, so that the non-ionizing radiation emitted by the barium fluoride is not directly reabsorbed by said barium fluoride itself. Indeed, such reabsorption would reduce the efficiency of the detector since a smaller proportion of the non-ionizing radiation emitted by the scintillator would reach the catalyst and the monomer.Finally, barium fluoride has the advantage of being only slightly hygroscopic. Indeed, a highly hygroscopic solid scintillator would capture moisture from the air, and a thin layer of water would adsorb on the surface of said highly hygroscopic scintillator. The thin layer of water would absorb at least some of the alpha radiation, which would therefore not reach the scintillator, reducing the efficiency of the detector. Barium fluoride emits continuously between 170 nm and 460 nm with emission maxima at 195 nm, 220 nm (fast component) and 310 nm (slow component).

[0113] Thus, the monomers used in the detector of the invention, in particular the monomers of formula (I), are advantageously used in conjunction with a scintillator comprising, in particular consisting of, barium fluoride, the main absorption band of the monomer of the invention (absorption maximum between 200 nm and 300 nm) overlapping with the emission band of said barium fluoride. More generally, the monomers used in the detector of the invention are advantageously used in conjunction with any scintillator whose emission spectrum has an emission band in the UVC, for example an emission band whose absorption maximum is between 200 nm and 300 nm. For example, the monomer of formula (IA) can advantageously be coupled to any scintillator whose emission spectrum has an emission band whose absorption maximum is close to 254 nm.

[0114] Definition of catalyst

[0115] The catalyst used in the detector of the invention and as described in the present description can be chosen so that its absorption spectrum extends in a wavelength range between 250 nm and 475 nm. In other words, the catalyst can be chosen to be sensitive to the near visible (between 400 nm and 475 nm), to UVA (between 320 nm and 400 nm), to UVB (between 280 nm and 320 nm) and / or to near UVC (between 250 nm and 280 nm).

[0116] The catalyst used in the detector of the invention is typically selected from the group consisting of type I or type II catalysts, including benzophenones, quinones and their derivatives. Benzophenones, quinones and their derivatives are particularly advantageous when coupled to barium fluoride and a diacetylene monomer. Indeed, benzophenones, quinones and their derivatives have an absorption band centered around a wavelength between 440 nm and 470 nm which overlaps with the emission spectrum of the BaF2 scintillator and which is disjoint from the absorption band around 250 nm of the diacetylene monomers, so that the diacetylene monomer / quinone or benzophenone duo absorbs a large proportion of the non-ionizing radiation emitted by the barium fluoride.More generally, quinones, benzophenones and their derivatives can be used in conjunction with any scintillator having an emission band overlapping with their absorption band between 440 nm and 470 nm.

[0117] The catalyst is present in small quantities relative to the monomer. For example, the amount of catalyst is between 0.01% and 10% by mass relative to the mass of the monomer initially present in the detector.

[0118] In a preferred embodiment, the monomer and the catalyst are included in the same solid composition. The solid composition may be in the form of a powder or a mixture of powders. Alternatively, the solid composition may be in the form of a layer or a film, called a solid layer composition, resulting for example from the compaction of a powder or a mixture of powders, or from the imprisonment of a powder or several powders in a polymer matrix, said solid layer composition constituting the active layer of the detector. The solid state polymerization of the monomer included in the solid composition advantageously makes it possible to avoid the use of a solvent and therefore problems related to the sealing of the detector and the toxicity of the solvent.

[0119] The solid composition preferably comprises a powder of monomer crystals, the catalyst being incorporated directly into said monomer crystals. In other words, within the monomer crystals, the monomeric units are arranged in a well-ordered and regular spatial arrangement, and the catalyst is very advantageously intercalated between said well-ordered monomeric units. Such an embodiment of the solid composition very advantageously makes it possible to obtain a very close proximity between the catalyst molecules and the monomer molecules, so that all the catalyst molecules are able to initiate the polymerization.

[0120] Preferably, the solid composition does not comprise a polymer binder and / or additives other than the monomer and the catalyst. For example, the solid composition does not comprise an opacifier, colorant and antioxidant. For example, the solid composition consists solely of the powder of monomer crystals in which the catalyst is incorporated, said powder being able to be compacted in the form of a layer or a film as previously mentioned. A solid composition not comprising a polymer binder advantageously makes it possible not to dilute the monomer in a neutral polymer matrix which could lead to the formation of monomer clusters, and therefore to a lower visual impact of the color change compared to the configuration in which the same quantity of monomer is distributed homogeneously in the solid composition.Furthermore, by intercalating polymer chains of the polymer binder between the monomers, there is a risk of breaking the spatial arrangement of the monomers and therefore of obtaining a lower reactivity of the monomer. Thus, for the same absorbed dose of ionizing radiation, the use of a polymer binder leads to a less pronounced color change. A solid composition not including additives other than the monomer and the catalyst allows for a detector that is easier to shape.

[0121] As previously mentioned, the catalyst of the detector according to the invention advantageously makes it possible to increase the sensitivity of said detector, so that the change in color is visible to the naked eye for very low absorbed doses of ionizing radiation (of the order of a few hundred pGy after approximately 5 hours of exposure with an activity source of the order of a few tens of Bq / cm 2) without the need to add an opacifier and / or a dye to said detector.

[0122] Preferably, the arrangement of the solid composition within the detector makes it possible to replace said solid composition after use of the detector without having to discard the other elements of said detector, the use of the detector being understood as an exposure of said detector to ionizing radiation having led to the polymerization of the monomer and to the change in color of the detector.

[0123] In the case of a solid layered composition, said solid layered composition may be arranged on a support. The support is for example in the form of a polymer film typically comprising polyester, polyethylene, polypropylene and / or polyethylene terephthalate. The thickness of the support is for example between 10 μm and 2 mm.

[0124] According to a first particular embodiment of the detector shown in Figure 1, the scintillator is included in a solid layer composition further comprising the monomer and the catalyst called scintillating active layer 2, said solid composition itself being able to be arranged on a support 1 as previously described. For example, the scintillating active layer 2 comprises a compacted mixture of a powder comprising the scintillator and a powder of monomer crystals in which the catalyst is incorporated. The powder comprising the scintillator may be a powder of pure scintillator crystals.

[0125] In such an embodiment, the catalyst and possibly the monomer are also capable of absorbing ionizing radiation, in addition to absorbing non-ionizing radiation re-emitted by the scintillator. This double absorption makes it possible to generate more active sites and accelerate polymerization. The response time of the detector is thus reduced.

[0126] In the embodiment shown in Figure 1, the scintillator is advantageously close to the monomer and the catalyst, so that the absorption by the monomer / catalyst pair of the non-ionizing radiation emitted by the scintillator is efficient with little loss of said non-ionizing radiation emitted by the scintillator due to the geometry. Indeed, the scintillator emits the non-ionizing radiation in all directions in space: the further the scintillator is from the monomer / catalyst association, the smaller the solid angle at which said non-ionizing radiation leaving the scintillator actually reaches the monomer / catalyst association. In the embodiment shown in Figure 1 in which the scintillator is mixed with the monomer / catalyst association, the solid angle is maximized and the geometric losses are limited to edge effects.This embodiment also has the advantage of avoiding interface problems between the active layer and the scintillating layer (detachment, etc.) and the thickness to be crossed by the ionizing radiation and / or the non-ionizing radiation is smaller, the radiation being thus absorbed more quickly. There is thus less loss of energy from the radiation. Finally, the manufacture of the device shown in Figure 1 requires only a single step to deposit the scintillating active layer comprising the scintillator, the monomer and the catalyst when the embodiment shown in Figure 2 requires at least two: a first to deposit the non-scintillating active layer and a second to deposit the scintillating solid layer.

[0127] In the embodiment shown in Figure 1, the scintillating active layer 2 has a thickness preferably between 10 pm and 200 pm, in particular between 50 pm and 100 pm.

[0128] Preferably, the detector of Figure 1 further comprises means for attaching the scintillating active layer 2 to the support 1 which are reversible. For example, the detector of Figure 1 does not comprise glue at the interface between the scintillating active layer 2 and the support 1. Thus, the scintillating active layer 2 can be replaced after use of the detector and said detector reused. For this purpose, the means for attaching the scintillating active layer 2 to the support 1 may comprise an outer frame. For example, the outer frame may comprise a back board, a front board and a press.When the detector is positioned inside the outer frame, the scintillating active layer 2 is arranged on the support 1 and the superposition of the scintillating active layer 2 and the support 1 is interposed between the rear board and the front board of the outer frame, the press of the outer frame applying a clamping pressure of the front board against the rear board, so that the scintillating active layer 2 is kept fixed against the support 1. Alternatively, the support may form the rear board of the outer frame.

[0129] The press comprises for example at least two wing screws. According to this embodiment, the rear board and the front board each comprise at least two holes, each hole in the rear board coinciding with a hole in the front board when the detector is mounted inside the outer frame. Each wing screw is configured so that, when the detector is mounted inside the outer frame, the wing screw passes through a hole in the front board and the hole in the rear board which coincides with the hole in the front board, and applies a clamping pressure of the front board against the rear board. The wing screws advantageously make it possible to limit the FME (acronym for the English term "Foreign Material Exclusion") risk, in particular when the detector is intended to be used in a building of a reactor of a nuclear power plant.In fact, in this type of building, it is important not to lose tools which, if they fall into the reactor, could damage the fuel assemblies of the reactor in operation.

[0130] Alternatively, the pressure comprises at least two clamps, for example at least two toggle clasps or at least two butterfly clasps: the pressure for clamping the front board against the rear board is applied by said clamps when the overlap of the rear board and the front board inside which the detector is inserted is inserted between the clamps.

[0131] Preferably, the outer frame is configured so that when the detector is mounted inside said outer frame, the change in color of the scintillating active layer can be visually observed directly without removing the frame. For example, the front board of the outer frame comprises a through hole.

[0132] Description of two embodiments of the detector where the scintillator is not included in the solid composition comprising the monomer and the catalyst In a second preferred embodiment, the scintillator is not included in the solid composition. In such an embodiment, the solid layer composition, called the non-scintillating active layer, has a thickness preferably ranging from 100 μm to 1 mm. Such a range of thicknesses advantageously makes it possible to absorb all or almost all of the non-ionizing radiation emitted by the scintillator passing through the non-scintillating active layer, so that no non-ionizing radiation or a minimal fraction of the non-ionizing radiation reaches the support. The polymer film of the support absorbs this minimal fraction of the non-ionizing radiation, so that there is no or very little backscattering of the non-ionizing radiation emitted by the scintillator towards the active layer.

[0133] In such an embodiment, the scintillator is not an additive that dilutes the solid composition. Furthermore, when the scintillator is not included in the solid composition, the ionizing radiation is emitted more homogeneously. Finally, the scintillator can in such a configuration be changed independently of the active layer. a. Scintillator included in a scintillating solid layer separate from the monomeric solid composition and the

[0134] In a particular embodiment of the detector where the scintillator is not included in the solid composition, shown in Figure 2, the scintillator is included in a scintillating solid layer 5 arranged on a layered solid composition comprising the monomer and the catalyst called non-scintillating active layer 4, said non-scintillating active layer 4 itself being able to be arranged on a support 3 as previously described. The detector comprises in this case, from a rear face to a front face: the support 3, the non-scintillating active layer 4 and the scintillating solid layer 5. For example, the scintillator is in the form of a crystal which constitutes the scintillating solid layer 5.

[0135] When the detector according to the embodiment shown in Figure 2 is exposed by its front face to ionizing radiation emitted by contaminations, for example alpha particles, the scintillating solid layer 5 comprising the scintillator absorbs the ionizing radiation, and re-emits non-ionizing radiation in all directions, in particular towards the non-scintillating active layer 4 comprising the monomer and the catalyst. The catalyst absorbs this radiation, so as to catalyze the polymerization reaction of the monomer. In order to avoid the loss of the non-emitted non-ionizing radiation towards the non-scintillating active layer 4, the detector may further comprise an external reflective layer enveloping the rest of the detector to return more of the non-ionizing radiation emitted by the scintillator towards the non-scintillating active layer 4. For example, the external reflective layer may be a mylar layer.

[0136] The scintillating solid layer 5 has a thickness preferably ranging from 0.3 mm to 5 mm. Such a thickness of the scintillating solid layer advantageously makes it possible to minimize the reabsorption by said scintillating solid layer 5 of the non-ionizing radiation emitted by the scintillator while maintaining a self-supporting scintillating solid layer. The scintillating solid layer 5 is for example a scintillator crystal layer which does not comprise other compounds. A scintillator crystal layer not comprising other compounds advantageously makes it possible not to dilute the scintillator in the solid layer comprising said scintillator 3 with additives and to obtain a homogeneous emission of non-ionizing radiation.

[0137] The thickness of the support 3 typically ranges from 10 pm to 2 mm.

[0138] Preferably, the detector of Figure 2 further comprises means for fixing the non-scintillating active layer 4 to the support 3 and / or to the scintillating solid layer 5 which are reversible. For example, the detector does not comprise glue at the interface between the non-scintillating active layer 4 and the support 3 on the one hand, and at the interface between the non-scintillating active layer 4 and the scintillating solid layer 5 on the other hand. Thus, the non-scintillating active layer 4 can be replaced after use of the detector and said detector reused. For this purpose, the means for fixing the non-scintillating active layer 4 to the support 3 and / or to the scintillating solid layer 5 may comprise an outer frame as previously described for the embodiment of Figure 1.

[0139] The particular embodiment of the detector where the scintillator is not included in the active layer, shown in Figure 2, advantageously makes it possible to obtain non-ionizing radiation emitted by the scintillator which is more homogeneous than in the case where said scintillator is included in the active layer. b. Scintillator included in a scintillating liquid

[0140] In another embodiment of the detector where the scintillator is not included in the solid composition, shown in Figure 3, the scintillator is included in a liquid called scintillator liquid 6. For example, the scintillator is liquid and alone in its phase. Alternatively, the scintillator liquid 6 may be a commercially available scintillator cocktail of the type ULTIMAGOLD ™ supplied by PerkinsElmer or PROSAFE ™ supplied by Meridian (Hidex). The scintillator liquid 6 may be contained in a vial 7. In the embodiment of Figure 3, the detector further comprises a solid composition, said solid composition comprising the monomer and the catalyst, which is insoluble in the scintillator liquid 6. As previously mentioned, the solid composition may be in the form of a powder or a mixture of powders.For example, the solid composition may be in the form of a powder of monomer crystals in which the catalyst is incorporated. The powder or mixture of powders may be directly immersed in the scintillating liquid 6, the powder or mixture of powders being insoluble in said scintillating liquid 6.

[0141] Alternatively, the solid composition may be a layered solid composition optionally arranged on a support as previously described, such that said layered solid composition and said support together form a strip 8. For example, the layered solid composition of the strip 8 is a compacted powder of monomer crystals in which the catalyst is incorporated.

[0142] The thickness of the solid composition of the strip 8 typically ranges from 100 μm to 1 mm, and the thickness of the support 3 typically ranges from 10 μm to 2 mm.

[0143] The strip 8 may be immersed directly in the scintillating liquid 6 contained in the bottle 7, for example by insertion through a slot in said bottle 7. Alternatively, the wall of the bottle 7 may comprise a recess towards the inside of the bottle 7, said recess forming a first cavity of the bottle 7 inside a second cavity of the bottle 7, the second cavity being closed and containing the scintillating liquid 6, the first cavity being open and adapted so that the strip 8 can be inserted inside said first cavity. Thus, when the strip 8 is inserted inside the first cavity, the strip 8 is generally surrounded by scintillating liquid 6 without being directly immersed in said scintillating liquid 6. This embodiment in which the strip is not immersed makes it possible to limit the risks of contamination when removing the strip.

[0144] The embodiment of the detector according to Figure 3 advantageously makes it possible to maximize for each monomer or catalyst molecule the probability of the solid composition absorbing non-ionizing radiation emitted by the scintillator since each monomer or catalyst molecule “sees” the non-ionizing radiation emitted by the scintillator at any solid angle. In the embodiment of Figure 2, on the contrary, each monomer or catalyst molecule of the non-scintillating active layer “sees” the non-ionizing radiation emitted by the scintillator from only one side. Tl

[0145] In order to optimize the exposure of the strip to the non-ionizing radiation emitted by the scintillator, the strip may have cylindrical symmetry and the solid composition may be arranged around the periphery of said support. For example, the support may be a plastic rod covered with solid composition.

[0146] Advantageously, the wall of the bottle 7 comprises a material which reflects the non-ionizing radiation emitted by the scintillator, for example a Teflon or Mylar wall, to avoid losing the non-ionizing radiation emitted by the scintillator inside the bottle 7 to the outside of the bottle. In the case where the bottle 7 comprises a recess, the portion of the wall of the bottle 7 forming the recess is on the contrary formed from a material transparent to the non-ionizing radiation emitted by the scintillator, so that said ionizing radiation can be transmitted to the strip 8 inserted inside the first cavity.

[0147] In use of the detector, a smear of the area suspected of contamination can be introduced into the scintillating liquid 6 of the bottle 7. The scintillator included in the scintillating liquid 6 absorbs the ionizing radiation emitted by the contaminations present on the smear and generates non-ionizing radiation. Said non-ionizing radiation is absorbed by the catalyst and by the monomer, which triggers the polymerization and causes the color change.

[0148] The strip 8 is preferably replaceable with a new strip, so that after introducing a smear into the scintillating liquid 6 or into the recess of the bottle 7 and staining the strip 8, the detector can be reused with a new smear.

[0149] Filtering layer for external non-ionizing radiation

[0150] Regardless of the embodiment of the detector, said detector preferably comprises an external layer arranged so as to filter non-ionizing radiation, for example ultraviolet radiation, external to the devices. Such a non-ionizing radiation filtering layer advantageously makes it possible to protect the active layer from natural and artificial non-ionizing radiation, in particular when the monomer and / or the catalyst are likely to absorb said non-ionizing radiation, which would have the effect of initiating the polymerization reaction and the change in color of the detector without any link to a dose of ionizing radiation potentially absorbed by the scintillator.For example, an ultraviolet ray filtering layer can be advantageously used when the monomer is a diacetylenic compound and the catalyst is a compound chosen from quinones and benzophenones due to the high sensitivity of said monomer and of the quinones and benzophenones to ultraviolet radiation.

[0151] For example, in the particular embodiments of Figures 1 and 2, the filtering layer may be a filtering film 9. In the embodiment of Figure 2, the filtering film 9 may be arranged on a front face of the scintillating solid layer 5 opposite the non-scintillating active layer 4 of the detector, so that the scintillating solid layer 5 is located between the filtering film 9 and the non-scintillating active layer 4. Such an arrangement of the layers advantageously makes it possible not to expose the non-scintillating active layer 4 to non-ionizing radiation other than that emitted by the scintillator.

[0152] In the embodiment of figure 1, the filtering film 9 can be arranged on a front face of the scintillating active layer 2 opposite the support 1, so that the scintillating active layer 2 is located between the filtering film 9 and the support 1. Such an arrangement of the layers advantageously makes it possible not to expose the scintillating active layer 2 to non-ionizing radiation external to the device.

[0153] The thickness of the filtering film 9 preferably ranges from 1 μm to 10 μm. Such a thickness of the filtering film 9 advantageously makes it possible not to block the diffusion of ionizing radiation, in particular alpha radiation, towards the scintillator.

[0154] The filtering film 9 may be a transparent film comprising a polymer, for example polyester, polyethylene, polypropylene and / or polyethylene terephthalate, and a compound which absorbs non-ionizing radiation, in particular ultraviolet radiation, for example bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and / or methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate. Such a filtering film 9 is for example advantageously obtained by a spin-coating, coating or dip-coating process.

[0155] For example again, in the embodiment of Figure 3, the outer non-ionizing radiation filtering layer may be included in the walls of the bottle 7 containing the scintillating liquid 6, so that the strip 8 inside the bottle 7 is not exposed to natural and artificial non-ionizing radiation outside the bottle 7 which could distort the measurement in the case where the polymerization of the monomer can be triggered by the exposure of the monomer and / or the catalyst to said non-ionizing radiation. For example, the bottle 7 is a commercially available tinted bottle.

[0156] Detector specific for the detection of alpha radiation In a particular embodiment, the detector is specific for alpha radiation, that is to say that it changes color in the presence of alpha radiation and not in the presence of beta radiation and / or gamma radiation.

[0157] For example, the detector is according to the embodiment of Figure 2 and further comprises one or more features described below which confer the detector specificity to alpha radiation.

[0158] In particular, in this embodiment, the scintillator is chosen from plastic scintillators such as BC400™, BC404™, BC408™, BC412™ and BC412™ and / or from inorganic scintillators such as ZnS(Ag) and CaF2(Eu) and / or ceramic scintillators such as GAGG™ and GPS™ previously mentioned. Indeed, such scintillators have the advantage of detecting alpha radiation better than other scintillators known to those skilled in the art even if they are not specific for said alpha radiation.

[0159] Additionally or alternatively, the detector is advantageously configured so that the thickness of the scintillating solid layer is between 0.3 mm and 0.5 mm, and the thickness of the non-scintillating active layer is between 20 pm and 50 pm, the support being further made of a polished material, for example glass, mylar or aluminum. Indeed, the alpha particles will deposit all their energy in the scintillating solid layer over a thickness of at most 50 pm, or even 25 pm. The thicknesses of the scintillating solid layer and the non-scintillating active layer must therefore be as small as possible so that the beta particles passing through said layers deposit little energy there and so that the gamma rays are not absorbed.A polished support advantageously makes it possible not to reflect beta particles and gamma radiation, so that said particles and said radiation are not backscattered in the non-scintillating active layer when they arrive on the support. However, a thickness of the scintillating solid layer less than 0.3 mm would pose problems of manufacturability of said scintillating solid layer.

[0160] An embodiment of the detector optimized to be specific for the detection of alpha radiation also makes it possible to obtain a detector with low sensitivity to the previously mentioned gamma background noise and therefore to avoid the need to implement indirect measurements by first carrying out smears and then analyzing said smears in a low gamma background noise zone. Method for detecting ionizing rays

[0161] The invention also relates to a method for detecting ionizing radiation, for example a method for detecting ionizing radiation emitted by radioactive substances contaminating a room.

[0162] The method for detecting ionizing radiation comprises a preliminary step E0 of providing a scintillator, a monomer and a catalyst. The scintillator, the monomer and the catalyst are as defined previously.

[0163] The method for detecting ionizing radiation further comprises a first step E1 of emission by the scintillator of non-ionizing radiation in at least one wavelength band, following absorption of ionizing radiation by the scintillator. The ionizing radiation is for example emitted by a particle emitting ionizing radiation.

[0164] The method for detecting ionizing radiation comprises a second step E2 of polymerization of the monomer, the polymerization being catalyzed by the catalyst, following absorption by the catalyst of at least part of the non-ionizing radiation emitted by the scintillator, the resulting polymer having a color different from the monomer.

[0165] Preferably, the polymerization of step E2 is also induced by the absorption by the monomer of at least a portion of the non-ionizing radiation emitted by the scintillator. Thus, the polymerization is jointly initiated by polymerization initiator sites generated from the catalyst and by polymerization initiator sites generated from the monomer. In this embodiment of the detection method, the emission spectrum of the scintillator and the absorption spectrum of the monomer overlap at least partially.

[0166] The method for detecting ionizing radiation comprises a third step E3 of observing with the naked eye a change in color when the absorbed dose value of ionizing radiation by the detector exceeds a threshold value. The change in color may in particular be the appearance of a color. The change in color is preferentially observable with the naked eye for doses of absorbed ionizing radiation of the order of a few hundred pGy after approximately 5 hours of exposure with an activity source of the order of a few tens of Bq / cm 2 . Optionally, the observation with the naked eye of the color change can be supplemented by a step E4 of quantification of the absorbed dose. Said evaluation can comprise the comparison of the color of the polymer to a scale linking said color to the absorbed dose.

[0167] Implementation of direct measures

[0168] In a particular embodiment of the detection method according to the invention, the supply E0 of the scintillator, the monomer and the catalyst comprises the arrangement E0' of said scintillator, monomer and catalyst in a construction site area or on an object of said construction site and then the implementation EO” of the work to be carried out on said construction site, so as to carry out so-called “direct” measurements. A construction site is understood to mean any area on which maintenance or dismantling work is to be carried out, said area being likely to be contaminated during the course of said work. For example, it may be a maintenance or dismantling site of a nuclear power plant. As another example, the detector may be arranged on the walls of a room, or on a pipe, a hose, a hammer, scaffolding or any object of complex shape.

[0169] According to this particular embodiment of the detection method, the observation of the color change with the naked eye in step E3 may be followed by an additional step of stopping work and / or decontaminating the area of ​​the construction site or the contaminated object.

[0170] The detection method according to this embodiment advantageously allows a site operator to continuously monitor during work carried out on said site and remotely, by simple visual inspection, the radiological state (defined by the absence or presence of contamination) of the area of ​​the site in which the scintillator, the monomer and the catalyst or the tool on which they are placed are arranged. When contamination occurs during the work, the operator is immediately informed of said contamination simply by perceiving the change in color without needing to approach to carry out an additional measurement, which limits the risk of contamination of said operator during the measurement operation. In addition, the change in color allows him to immediately adapt his intervention as needed.

[0171] Alternatively or additionally, the EO' arrangement of said scintillator, monomer and catalyst can be made on the workers' outfits, in the airlocks and / or to monitor the undressing operations of said workers.

[0172] In the particular embodiment of the detection method where the EO supply of the scintillator, the monomer and the catalyst comprises the EO' arrangement of said scintillator, monomer and catalyst in a construction site area or on an object of said construction site and then the EO” implementation of the work to be carried out on said construction site, the scintillator, the monomer and the catalyst are preferably supplied in a solid form.

[0173] For example, the scintillator, monomer, and catalyst are provided in the form of a detector according to any of the previously described embodiments where the scintillator is in a solid form.

[0174] In the particular case where the detector comprises a scintillating or non-scintillating active layer comprising the monomer and the catalyst, for example a layer comprising a compacted powder of monomer crystal in which the catalyst is incorporated, said active layer being reversibly fixed to the other elements of the detector, the detection method may further comprise a step E4 of changing the active layer which has changed color with a new non-colored active layer.

[0175] First implementation method for indirect measures

[0176] Alternatively, the EO supply of the scintillator, the monomer and the catalyst may comprise a sub-step EO' of carrying out a smear on an area or a tool of a construction site suspected of being contaminated and then a sub-step EO” of bringing said smear into contact with the scintillator, so that the ionizing radiation absorbed by the scintillator in step E1 is the ionizing radiation emitted by the contaminations on the smear. In this case, so-called "indirect" measurements are carried out.

[0177] In the particular embodiment of the detection method where the supply EO of the scintillator, the monomer and the catalyst comprises a sub-step EO' of making a smear on an area or a tool of a construction site suspected of being contaminated and a sub-step EO” of bringing said smear into contact with the scintillator, the scintillator is preferably supplied in a liquid form. For example, the scintillator is included in a liquid, called scintillating liquid, and bringing the smear into contact with the scintillator corresponds to immersing said smear in the scintillating liquid comprising the scintillator, for example until said smear is completely dissolved or for a shorter period of time sufficient for there to be migration of the contamination from the smear to the scintillating liquid. More specifically, the scintillating liquid may be contained in a bottle with a stopper.The contacting of the smear with the scintillator EO” may comprise the successive steps of opening the cap, immersing the smear in the scintillating liquid and closing the cap. According to this embodiment of the detection method, the provision E0 of the scintillator, the monomer and the catalyst may further comprise a step EO'” of exposing the monomer and the catalyst to the non-ionizing radiation emitted by the scintillator following the contacting of the scintillator with the smear, for example by means of a strip comprising a non-scintillating active layer deposited on a support as previously described. The use of a strip advantageously makes it possible to carry out, for the same smear, several successive measurements by simply changing the strip.

[0178] According to a particular embodiment of step EO'”, the exposure of the strip to the non-ionizing radiation emitted by the scintillator comprises the insertion of the strip into a slot of the bottle containing the scintillating liquid, so as to immerse said strip in the scintillating liquid and steps E3 and E4 may be preceded by a step of extracting the strip from the bottle through the insert to be able to observe the change in color if it is not visible through the walls of the bottle (despite exposure to radiation from the outside, the strip will not have time to change color over the reading time which is very short). In such an embodiment, the active layer must not be soluble in the scintillator.

[0179] According to another embodiment of step EO'”, the wall of the vial comprises a recess as previously described and step EO'” is a step of inserting the strip into the recess of the vial so that the monomer and the catalyst comprised in the non-scintillating active layer of the strip are exposed to the non-ionizing radiation emitted by the scintillator which is comprised in the scintillating liquid contained in the vial without immersion of said strip. Such an embodiment of step EO'” avoids the problems of interference of the strip material with the scintillating liquid comprising the scintillator. In such an embodiment, step EO'” can be carried out before or after step EO”.

[0180] Second embodiment for the implementation of indirect measures

[0181] In an alternative embodiment of the indirect measurements, the provision EO of the scintillator, the monomer and the catalyst may comprise a sub-step EO' of making a smear on an area or a tool of a construction site suspected of being contaminated, a sub-step EO” of bringing the monomer, the scintillator and the catalyst into contact and then a sub-step EO'” of bringing said smear into contact with the scintillator itself in contact with the monomer and the catalyst, so that the ionizing radiation absorbed by the scintillator in step E1 is the ionizing radiation emitted by the contaminations on the smear.For example, the scintillator may be included in a scintillating liquid itself contained in a bottle, so that the sub-step E0” of bringing the monomer, the scintillator and the catalyst into contact may comprise mixing the monomer and catalyst powder, for example the monomer crystal powder in which the catalyst is incorporated, with the scintillating liquid, and the sub-step EO'” of bringing the smear into contact with the scintillator corresponds to immersing said smear in the scintillating liquid comprising the scintillator, the monomer and the catalyst. Once again, the contacting of the smear may last for example until said smear is completely dissolved or for a shorter period sufficient for there to have been migration of the contamination from the smear to the scintillating liquid.

[0182] In such an embodiment, the monomer and catalyst powder must not be soluble in the scintillator. In addition, the vial must be transparent while not allowing non-ionizing radiation to pass through so that the color can be visually detected. However, said embodiment has the advantage of being simple to implement. For example, it does not require a strip.

[0183] Manufacturing process of an ionizing ray detector

[0184] The invention extends to a method of manufacturing an ionizing radiation detector comprising a monomer, a catalyst for the polymerization reaction of the monomer and a scintillator, in particular to a method of manufacturing an ionizing radiation detector according to any one of the embodiments previously described.

[0185] More specifically, the method for manufacturing an ionizing radiation detector comprises a step a) of providing the scintillator emitting non-ionizing radiation in at least one wavelength band following absorption of ionizing radiation by the scintillator.

[0186] The manufacturing method further comprises a step b) of arranging a monomer relative to the scintillator and a step c) of arranging a catalyst relative to the monomer and the scintillator such that the catalyst initiates polymerization of the monomer following absorption by the catalyst of the radiation emitted by the scintillator, the resulting polymer having a different color from the monomer.

[0187] The monomer, catalyst, and scintillator are as previously mentioned. Optionally, the monomer also absorbs the non-ionizing radiation emitted by the scintillator. The arrangement of the monomer relative to the scintillator is therefore made so that the monomer also polymerizes due to the absorption by the monomer of the non-ionizing radiation emitted by the scintillator.

[0188] For example, the scintillator can be arranged in a first solid layer called a scintillating solid layer distinct from a second layer comprising the monomer and the catalyst called a non-scintillating active layer, so that the detector comprises from a rear face to a front face: a support, a non-scintillating active layer and a scintillating solid layer.

[0189] In the following, an example of a method for manufacturing a detector of ionizing radiation is described in which the scintillator is arranged in a scintillating solid layer separate from the non-scintillating active layer comprising the monomer and the catalyst.

[0190] Example of an embodiment of the method of manufacturing a detector in which the scintillator is arranged in a scintillating solid layer separate from the non-scintillating active layer comprising the monomer and the catalyst

[0191] A 1. Formation of the non-flickering active layer

[0192] Preferably, the non-scintillating active layer comprises the monomer in an ordered crystalline form, the catalyst being incorporated into the crystal of the monomer.

[0193] When the non-glittering active layer comprises the monomer in an ordered crystalline form, the catalyst being incorporated into the crystal of the monomer, the arrangement of the catalyst relative to the monomer preferably comprises a recrystallization step so as to obtain a monomer crystal powder in which the catalyst is incorporated.

[0194] According to a particular embodiment of the recrystallization, the monomer and the catalyst are dissolved hot in a solvent. In an alternative embodiment of the recrystallization, the monomer and the catalyst are melted together without solvent. Such an embodiment of the recrystallization has the advantage of not comprising a potentially toxic solvent to evaporate. Said embodiment of the recrystallization is therefore easier to implement and less dangerous.

[0195] In the following, a particular example of the embodiment of recrystallization with solvent is described. The solvent is for example tetrahydrofuran or chloroform. Then, the solution obtained is left to cool to room temperature, i.e. between 18 °C and 25 °C. Said solution is then placed in the cold for a period preferably between 30 minutes and 48 hours, for example for one hour, so as to precipitate a crystal comprising the monomer and the catalyst. When the solution is placed in the cold, the temperature is preferably between -20 °C and 5 °C. Then, the solution is filtered, so as to recover the precipitated crystal. Finally, the crystal is preferably dried under vacuum at room temperature in order to remove the residual solvent.

[0196] The following describes a particular example of the solvent-free recrystallization method. The monomer and the catalyst are melted together without solvent at a temperature ranging from 90°C to 120°C. The resulting mixture is then allowed to cool to room temperature, i.e., between 18°C ​​and 25°C.

[0197] Alternatively to recrystallization, incorporation of the catalyst into the monomer crystal may include hot dissolution of the catalyst and monomer in a solvent followed by evaporation at room temperature, under vacuum or at atmospheric pressure, of said solvent.

[0198] The arrangement of the catalyst relative to the monomer further comprises a step of forming the non-scintillating active layer.

[0199] For example, the non-glittering active layer can be prepared by compacting a powder or a mixture of powders comprising the monomer and the catalyst: the powder or the mixture of powders comprising the monomer and the catalyst is deposited on a press support and then the powder is compacted using a press, so as to form the non-glittering active layer.

[0200] Preferably, the powder mixture comprises the monomer crystal powder in which the catalyst resulting from the recrystallization according to one of the embodiments previously described is incorporated.

[0201] Preferably again, the formation of the non-glittering active layer does not include additional steps of introducing a polymer binder or additives into the powder or powder mixture prior to deposition, so that the non-glittering active layer only includes the monomer in an ordered crystalline form, the catalyst being incorporated into the crystal of the monomer.

[0202] A2. Arrangement of the non-flickering active layer relative to the support The non-flickering active layer may be arranged on the support by a reversible attachment system, for example by means of an external frame as previously described. An arrangement between the non-flickering active layer and the reversible support advantageously makes it possible to replace the non-flickering active layer after use of the detector while keeping the same support.

[0203] Alternatively, the arrangement of the non-scintillating active layer on the support may comprise bonding using an adhesive which preferably does not degrade under radiation and does not emit parasitic non-ionizing radiation.

[0204] Alternatively, the arrangement of the non-glittering active layer on the support may comprise bonding the non-glittering active layer and the support by heating. In a first step of the bonding by heating, the two layers are heated to a temperature close to their melting point. For example, in the case where the non-glittering active layer is a layer of compacted powder of diacetylene monomer crystal, the two layers are heated to a temperature between 90°C and 120°C. Then, the two layers are brought into contact and allowed to cool together under pressure.

[0205] The support may be a polymer layer or film comprising, for example, polyester, polyethylene, polypropylene and / or polyethylene terephthalate, the thickness of the support being between 10 μm and 2 mm.

[0206] A3. Arrangement of the scintillating solid layer relative to the non-scintillating active layer

[0207] The scintillator may be provided in a solid form, for example in the form of a scintillating solid layer comprising said scintillator. The scintillating solid layer comprising the scintillator preferably has a thickness of between 0.1 mm and 5 mm. The scintillator may be used pure, so that the scintillating solid layer is a crystal layer of said scintillator.

[0208] According to this embodiment, the arrangement of the monomer and the catalyst relative to the scintillator is preferably understood as the arrangement of the scintillating solid layer on a face of the non-scintillating active layer opposite the support, so that the detector then comprises from a rear face of said detector to a front face: the support, the non-scintillating active layer and the scintillating solid layer.

[0209] The scintillating solid layer may be arranged on the non-scintillating active layer by reversible attachment means, for example by means of an external frame as previously described. The reversible attachment means between the scintillating solid layer and the non-scintillating active layer advantageously makes it possible to replace said solid layer composition after use of the detector without replacing the solid layer comprising the scintillator.

[0210] A4. Arrangement of a filter film

[0211] According to this embodiment, the method for manufacturing the ionizing radiation detector may further comprise a step of arranging a non-ionizing radiation filtering film on a front face of the scintillating solid layer opposite the non-scintillating active layer, so that the detector then comprises from its rear face to its front face: the support, the non-scintillating active layer, the scintillating solid layer and the non-ionizing radiation filtering film.

[0212] Preferably, the external non-ionizing radiation filtering film has a thickness of between 1 μm and 10 μm. Such a thickness of the external non-ionizing radiation filtering film is sufficiently low so as not to block the diffusion of alpha radiation towards the scintillating solid layer.

[0213] The arrangement of the external non-ionizing radiation filtering film is advantageously implemented so that no additional material is present between the external non-ionizing radiation filtering film and the scintillating solid layer. In particular, the arrangement of the non-ionizing radiation filtering film preferably does not use glue. Indeed, any additional material can absorb or scatter the ionizing radiation and / or the non-ionizing radiation emitted by the scintillator.

[0214] The arrangement of the external non-ionizing radiation filtering film may comprise the prior preparation of said filtering film, for example by spin-coating, coating or dip-coating, so as to obtain a self-supporting external non-ionizing radiation filtering film.

[0215] By "dip coating" we mean a deposition method where the surface to be treated is immersed and then removed from a solution / suspension at a defined speed (LD Landau, VG Levich, Acta physicochimica, USSR, 17, (1942), 42).

[0216] Spin coating is a deposition method where a solution / suspension is deposited on the surface to be coated. This same surface is fixed on a spinner which rotates it at a controlled speed which allows the suspension solution to spread and wet the entire surface (D. Meyerhofer, J. Appl. Phys., 49, (1978), 3993).

[0217] Coating means a means of deposition where a solution / suspension is deposited onto the surface to be coated at a controlled rate.

[0218] More specifically, the preliminary preparation of the external non-ionizing radiation filtering film may comprise the deposition, by coating, spin-coating or dip-coating as previously mentioned, on a support, of a solution comprising a polymer and additives which absorb non-ionizing radiation, for example on a polytetrafluoroethylene support, then the drying of said solution on the support so as to obtain the filtering film, and finally the detachment of the filtering film which is self-supported from the support. For example, the solution comprising the polymer and the additives is a polyethylene solution comprising the additive TINUV-2 from the company Stardust.

[0219] Such a method for preparing the filter film advantageously makes it possible to precisely control the thickness of the filter film and to obtain a filter film with a thickness of less than 10 μm. A filter film with such a low thickness is not commercially available.

[0220] Following the prior preparation of the self-supporting external non-ionizing radiation filtering film, the arrangement of the external non-ionizing radiation filtering film preferably comprises an additional step of fixing said self-supporting external non-ionizing radiation filtering film to the scintillating solid layer, for example by means of an external frame as previously described.

[0221] The arrangement of the external non-ionizing radiation filtering film may comprise the preparation of said external non-ionizing radiation filtering film directly on the scintillating solid layer. For example, the preparation of the external non-ionizing radiation filtering film may comprise the deposition by spin-coating, coating or dip-coating of a solution comprising a polymer and additives as previously described directly on the surface of the scintillating solid layer. According to this alternative, however, if the adhesion between the scintillating solid layer and the newly formed filtering film is good, the adhesion between said newly formed filtering film and the scintillating solid layer is definitive. In particular, the arrangement of the external non-ionizing radiation filtering film does not comprise an additional step of fixing said external non-ionizing radiation filtering film on the scintillating solid layer.In the following, an example of a method for manufacturing a detector of ionizing radiation is described in which the scintillator is arranged directly in the layer further comprising the monomer and the catalyst - called the scintillating active layer - so that said detector comprises from a rear face to a front face: a support and a scintillating active layer, the scintillating active layer comprising at least the scintillator, the monomer and the catalyst.

[0222] Example of an embodiment of the method for manufacturing a detector in which the scintillator is arranged in the layer further comprising the monomer and the catalyst - called the scintillating active layer.

[0223] The said method may therefore comprise:

[0224] B1) the arrangement of the catalyst relative to the monomer understood for example as the formation by recrystallization of a monomer crystal powder in which the catalyst is incorporated according to one of the embodiments of the recrystallization previously described;

[0225] B2) providing the scintillator in the form of a powder comprising the scintillator, for example a crystal powder of said pure scintillator;

[0226] B3) the arrangement of the scintillator relative to the monomer and the catalyst understood as the mixture of the powder comprising the scintillator and another powder comprising the monomer and the scintillator, for example the monomer crystal powder in which the catalyst is incorporated, followed by the deposition of said mixture on a support and the compaction, for example in a press, of said mixture so as to obtain the scintillating active layer comprising the scintillator, the catalyst and the monomer, called the scintillating active layer.

[0227] In the same way as previously described, the support may be a polymer layer or film comprising polyester, polyethylene, polypropylene and / or polyethylene terephthalate, the thickness of the support being able to be between 10 μm and 2 mm.

[0228] In the same way as previously described, the scintillating active layer can be arranged on the support by a reversible attachment system, such as an external frame, so that the non-scintillating active layer can be replaced after use of the detector while keeping the same support. Alternatively, the scintillating active layer can be arranged on the support by gluing using an adhesive, or by gluing by heating.

[0229] The method for manufacturing the detector of ionizing radiation in which the scintillator is arranged in the solid composition comprising the monomer and the catalyst may further comprise a step B4) of arranging a film for filtering external non-ionizing radiation on a front face of the scintillating active layer opposite the support, so that the detector then comprises from its rear face to its front face: the support, the scintillating active layer, and the film for filtering non-ionizing radiation. The arrangement of the film for filtering external non-ionizing radiation on the scintillating active layer may be done according to any one of the embodiments of said arrangement previously described.

[0230] For example, the arrangement of the external non-ionizing radiation filtering film on the scintillating active layer may comprise the prior preparation of a self-supporting external non-ionizing radiation filtering film according to any one of the embodiments previously described and then the fixing of said self-supporting external non-ionizing radiation filtering film on the scintillating active layer by reversible fixing means (for example an external frame) or non-reversible fixing means (for example by heating).

[0231] For further example, arranging the external non-ionizing radiation filtering film on the scintillating active layer may comprise preparing said external non-ionizing radiation filtering film directly on the scintillating active layer according to any of the previously described embodiments.

[0232] Example of an embodiment of the method of manufacturing a detector in which the scintillator is included in a scintillating liquid.

[0233] Alternatively, the scintillator may be provided not in a solid form but in a liquid form, such as a scintillating liquid comprising said scintillator. ULTIMAGOLD or PROSAFE are examples of commercially available scintillating liquids. In the following, an example of a method for manufacturing a detector of ionizing radiation comprising a bottle is described, said bottle comprising a slot or a recess as previously described and the scintillating liquid being disposed inside said bottle, the detector further comprising a strip. The strip comprises a non-scintillating active layer deposited on a support, the non-scintillating active layer comprising the monomer and the catalyst.

[0234] According to this embodiment, the arrangement of the catalyst relative to the monomer is understood as the manufacture of the strip. In the same way as previously described, the manufacture of the strip may comprise: - optionally, the preparation by recrystallization of a monomer crystal powder in which the catalyst is incorporated;

[0235] - the formation and arrangement on the support of the non-scintillating active layer. The steps of recrystallization of the monomer crystal powder in which the catalyst is incorporated and of formation and arrangement on the support of the non-scintillating active layer can be carried out according to any one of the embodiments previously described. In the case where the method comprises the preparation by recrystallization of the monomer crystal powder in which the catalyst is incorporated, the formation of the non-scintillating active layer comprises the compaction of said powder with possibly other powders.

[0236] According to this embodiment, the arrangement of the catalyst relative to the monomer and the catalyst is understood as filling the vial with the scintillating liquid and inserting the strip into the slot or recess of the vial.

Claims

CLAIMS 1. An ionizing radiation detector, the detector comprising a scintillator, a monomer and a catalyst, wherein: - the scintillator is capable of absorbing ionizing radiation and emitting non-ionizing radiation following the absorption of the ionizing radiation, - the catalyst is capable of absorbing at least part of the non-ionizing radiation emitted by the scintillator and of catalyzing the polymerization of the monomer following the absorption of at least part of the non-ionizing radiation emitted by the scintillator, - the polymer resulting from the polymerization of the monomer has a different color from the monomer.

2. Detector according to the preceding claim, in which the monomer and the catalyst are included in the same solid composition, said solid composition preferably being in the form of a powder, in particular a powder compacted in a layer arranged on a support.

3. Detector according to the preceding claim, in which the solid composition is replaceable after use of the detector.

4. Detector according to one of claims 2 or 3, in which the solid composition comprises the monomer in an ordered crystalline form, the catalyst being incorporated into the crystal of the monomer.

5. Detector according to one of claims 2 to 4, in which the solid composition does not comprise a polymer binder or additives.

6. Detector according to one of claims 2 to 5, in which the scintillator is not included in the solid composition.

7. Detector according to the preceding claim, in which the scintillator is comprised in a scintillating solid layer (5) arranged on the solid layer composition comprising the monomer and the catalyst.

8. Detector according to claim 6, wherein the scintillator is comprised in a scintillating liquid (6), the solid composition being insoluble in said scintillating liquid (6).

9. Detector according to one of the preceding claims, further comprising a filtering film arranged so as to filter ultraviolet radiation external to said detector.

10. Detector according to any one of the preceding claims, in which the monomer is a diacetylenic monomer of the following formula (I): R 1 -C CC CR 2 (I) in which R 1 and R 2are independently selected from an optionally substituted C1-C18 hydrocarbon chain, an optionally substituted aryl group and an optionally substituted heteroaryl group, wherein one or more, preferably 1 to 4 methylene groups of said hydrocarbon chain are optionally replaced by O, C(O), NH or N-(C1-C18alkyl).

11. Detector according to any one of the preceding claims, in which the monomer is capable of absorbing at least part of the non-ionizing radiation emitted by the scintillator.

12. Detector according to the preceding claim, in which the monomer is not capable of absorbing at least one wavelength at which the catalyst is capable of absorbing non-ionizing radiation and / or the catalyst is not capable of absorbing at least one wavelength at which the monomer is capable of absorbing non-ionizing radiation from the scintillator.

13. Detector according to any one of the preceding claims, in which the scintillator comprises barium fluoride BaF2 and / or in which the catalyst is chosen from quinones and benzophenones.

14. Method for detecting ionizing radiation comprising the following steps: E0) Provision of a detector as defined in claims 1 to 13, E1) Emission by the scintillator of non-ionizing radiation following absorption of ionizing radiation, E2) Polymerization of the monomer, the polymerization being catalyzed by the catalyst, following absorption by the catalyst of at least part of the non-ionizing radiation emitted by the scintillator, the resulting polymer having a color different from the monomer, E3) Observation with the naked eye of the color change.

15. Method of manufacturing an ionizing radiation detector comprising the following steps: - provide a scintillator capable of absorbing ionizing radiation and emitting non-ionizing radiation following absorption of the ionizing radiation, - arrange a monomer relative to the scintillator so that the device changes color when the monomer polymerizes, the resulting polymer having a different color from the monomer, - arranging a catalyst relative to the monomer and the scintillator, the catalyst being capable of absorbing at least a portion of the non-ionizing radiation emitted by the scintillator and of catalyzing the polymerization following the absorption of the at least a portion of the non-ionizing radiation emitted by the scintillator.

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