POLYMERIZATION COMPOSITION FOR THE PRODUCTION OF A SCINTILLATING HYBRID MATERIAL AND ASSOCIATED KITS

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of radioactivity measurement by the plastic scintillation technique.

[0002] The invention relates more particularly to a polymerization composition for manufacturing a material for measurement by plastic scintillation, kits for manufacturing the polymerization composition and a kit for manufacturing an extrusion mixture. TECHNICAL BACKGROUND

[0003] Plastic scintillation measurement consists of determining the presence and / or quantity of one or more radioactive materials, particularly in physics, geology, biology, medicine, for dating, environmental monitoring or control of the non-proliferation of nuclear weapons.

[0004] In practice, radioactive material emitting ionizing radiation or an ionizing particle (alpha particle, electron, positron, photon, neutron,...) is exposed to a scintillating material called a "plastic scintillator" which converts the energy deposit resulting from the radiation / matter interaction into light radiation (called radioluminescent) measurable by a photon-electron converter with gain, such as a photomultiplier.

[0005] The plastic scintillator has been known since the mid-20th century. It is described, for example, in the document "Moser, SW; Harder, WF; Hurlbut, CR; Kusner, MR; "Principles and practice of plastic scintillator design", Radiat. Phys. Chem., 1993, Vol. 41, No. 1 / 2, 31-36 » [reference 1] and “Bertrand, GHV; Hamel, M.; Sguerra, F.; “Current status on plastic scintillator modifications”, Chem. Eur. J., 2014, 20, 15660-15685 »[Reference 2]. It is generally presented as a polymer matrix into which a primary fluorophore, and sometimes a secondary fluorophore, is inserted. A fluorophore is a chemical compound capable of emitting visible fluorescence after excitation by photons or other incident particles. The primary and secondary fluorophores consist of an aromatic molecule with fluorescent properties (a molecule called a fluorophore) that allows detection by scintillation.

[0006] The polymer matrix's main function is to act as a support capable of receiving the energy from ionizing radiation or the ionizing particle. After recombination of the excited and / or ionized species that are formed, this energy is converted into radioluminescent radiation and then transferred to the primary fluorophore and possibly to the secondary fluorophore, which can increase the wavelength of the radiation emitted by the primary fluorophore in order to improve its detection.

[0007] A particular type of plastic scintillator called a phoswich (an Anglo-Saxon neologism resulting from the combination of the terms phosphorus and sandwich, generally translated as meaning "sandwich scintillator") was proposed early in the development of plastic scintillators in the document "Wilkinson DH, "The Phoswich - A Multiple Phosphor", Rev. Sci. Instrum. 1952, 23, 414-417 . » [reference 3].

[0008] In order to obtain new scintillation properties, a phoswich scintillator combines at least two compartments: one compartment comprising a slow scintillator on the one hand (high fluorescence decay constant, generally between 200 ns and 1000 ns) and another compartment comprising a fast scintillator (much lower fluorescence decay constant, generally between 2 ns and 7 ns on the other).

[0009] However, such a scintillator poses at least one of the following problems: The difference between the fluorescence decay constant of the fast compartment and that of the slow compartment is too small: the separation of scintillation pulses between these stages is then not possible electronically; the difference between the fluorescence decay constant of the fast compartment and that of the slow compartment is too large: the scintillation pulse of the slow scintillator may be partially or totally masked by the electronic background noise of the scintillation pulse acquisition device, leading to erroneous values. The acquisition of the luminescent signal is performed over a duration that is typically about 6 to 10 times the fluorescence decay constant of the slow compartment.In the case of a high count rate due to the multiplicity of ionizing particles or the high intensity of ionizing radiation interacting with the phoswich scintillator, the probability of stacking (i.e., two pulses present in the same acquisition time window) of scintillation pulses becomes increasingly significant. Consequently, several pulses may appear in the same acquisition time window, leading to the rejection of stacks due to saturation of the acquisition electronics, and therefore an underestimation of the count rate.

[0010] Furthermore, document WO 2015 / 118533 A1 describes a formulation for 3D printing scintillators, including plastic scintillators. Assuming, in the absence of explicit indication in this document, that the percentages given are weight percentages, formulation (h) would comprise 94.52 mol% naphthalene and 5.48 mol% 2,5-diphenyloxazole (PPO) as an additional primary fluorophore relative to the total number of moles of primary fluorophore in the formulation, as well as the prepolymer TMPTA.

[0011] US patent 2014 / 332689 A1 seeks to protect a plastic scintillator comprising a polymer matrix based on aromatic rings in which oxazole is incorporated. In an example intended to illustrate the principle of Pulse Shape Discrimination (PSD) between gamma and neutron radiation, the inventors use a plastic scintillation material that does not correspond to the claimed invention. This material does not comprise oxazole, but rather 10% naphthalene, 0.1% PPO, and 0.1% 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) incorporated into a polystyrene polymer matrix. Again, assuming, in the absence of an explicit statement in this patent, that the percentages indicated are weight percentages, the plastic scintillator material of the Figure 8 would comprise 99.42 molar percent of naphthalene and 0.58 molar percent of PPO relative to the total number of moles of primary fluorophore.

[0012] Document GB 1 377 703 A describes a scintillation composition comprising 0.05% to 10% of a compound of formula (I) dissolved in a transparent organic liquid or a " plastic solvent "consisting of polymers. A scintillation cocktail solution is prepared in Examples 1 and 2: it comprises 5 g / L of PPO as the primary fluorophore, 0.1 g / L of aminocoumarin as the secondary fluorophore, and 120 g / L of naphthalene in dioxane as the solvent. Expressed as a molar percentage, this is equivalent to a liquid fluorescent mixture comprising 97.64% naphthalene and 2.36% PPO. However, these solutions do not include monomers or oligomers intended to form a polymer matrix, or the resulting polymers." DESCRIPTION OF THE INVENTION

[0013] One of the aims of the invention is therefore to avoid or mitigate one or more of the disadvantages described above, in particular by proposing a polymerization composition to manufacture a new type of material constituting a plastic scintillator called a "hybrid material".

[0014] The present invention relates to a polymerization composition for manufacturing a hybrid material (as defined in this description, according to one or more of its variants) for detection by plastic scintillation comprising: monomers, oligomers or mixtures thereof intended to form at least one polymer constituting a polymeric matrix; a liquid fluorescent mixture comprising, in molar concentration relative to the total number of moles of primary fluorophore in the liquid fluorescent mixture: i) 95.6% to 99.1 mol% of a principal primary fluorophore consisting of naphthalene; and ii) 0.9% to 4.4 mol% of an additional primary fluorophore having a centroid of the light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent between 0.2 and 1.

[0015] The hybrid material for plastic scintillation measurement made with the polymerization composition of the invention, a material which is not itself part of the subject matter of the protection sought, comprises (or consists of): a polymeric matrix; and, a fluorescent mixture incorporated in the polymeric matrix and comprising, in molar concentration relative to the total number of moles of primary fluorophore in the incorporated fluorescent mixture: i) 95.6% to 99.1 mol% of a principal primary fluorophore consisting of naphthalene; and ii) 0.9% to 4.4% (more precisely 20.0%) mol of an additional primary fluorophore having a centroid of the light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent greater than 0.2, typically between 0.2 and 1; preferably greater than 0.5, typically between 0.5 and 1.

[0016] The aforementioned hybrid material may also exclude certain compounds, particularly when this material is used as described below, specifically for the part, device, apparatus, and their associated processes. More specifically, it does not include one or more of the following compounds, particularly in relation to the total weight of the material: a polymerization initiator, such as a photoinitiator, particularly TPO (2,4,6-Trimethylbenzoyl-diphenyl-phosphineoxide), more specifically 0.5% by weight of TPO. The use of a photoinitiator to initiate polymerization can indeed lead to scintillators with a lower scintillation yield, or even containing fluorophores subject to photobleaching by the activating photon source; and / or 15% naphthalene, 1.5% PPO, 0.08% POPOP, 0.5% TPO and the remainder TMPTA (trimethylolpropanetriacrylate ethoxylate); and / or 10% naphthalene, 0.1% PPO, 0.1% POPOP and the remainder polystyrene; and / or a metallic compound (i.e., a mineral or organometallic compound) comprising a metallic element selected, for example, from lead, tin, bismuth, or mixtures thereof. Such a metallic element may decrease scintillation yield; and / or a secondary fluorophore.

[0017] One or more of the exclusions of these compounds may also apply to the polymerization composition and / or the ready-to-use kit according to the invention as described below.

[0018] A suitable nonpolar solvent for measuring fluorescence quantum yield includes, for example, cyclohexane, toluene, dichloromethane, xylene, or any isomer of xylene.

[0019] The aforementioned material for plastic scintillation measurement may also be referred to in this description as a "plastic scintillator." It is called "hybrid" because its fluorescence decay constant is intermediate between that of a fast and a slow plastic scintillator. Advantageously, the value of this constant can be optimally selected during the manufacture of the hybrid material within an intermediate range of 10 ns to 90 ns (preferably between 15 ns and 80 ns), from values ​​between these two extremes which, to the inventor's knowledge, are not obtained with currently commercially available plastic scintillators. It may particularly be selected between 25 ns and 75 ns, and more particularly between 28 ns and 70 ns.

[0020] This temporal tunability of the fluorescence decay constant of the hybrid material is made possible by the use of a specific fluorescent mixture. This mixture is characterized in particular by the combined choice of naphthalene as the main primary fluorophore and an additional primary fluorophore with specific photophysical properties, as well as by the choice of a defined concentration ratio between these two primary fluorophores.

[0021] Unexpectedly, as demonstrated by the embodiments, the main primary fluorophore and the additional primary fluorophore act synergistically to significantly alter the fluorescence decay constant, even with a reduced concentration range for the additional primary fluorophore. Furthermore, the relative simplicity of this system, which essentially requires this combination of two primary fluorophores, avoids the addition of a potentially disruptive or costly extra molecule. These advantageous properties make the aforementioned hybrid material particularly effective for plastic scintillation measurements and readily achievable on an industrial scale at a moderate cost.

[0022] Contrary to the approaches taken by the state of the art, the aforementioned hybrid material does not involve the use of a new polymer matrix, the addition of an additive to the plastic scintillator, or the development of new families of molecules ("quantum dots," organometallic complexes, nanoparticles, etc.) as primary fluorophores to overcome at least one of the aforementioned drawbacks. Instead, it identifies the aforementioned fluorescent mixture that provides access to the hybrid material. The set of characteristics required for the aforementioned material for measurement by plastic scintillation can thus be essentially limited to a polymer matrix and the incorporated fluorescent mixture.The composition of the plastic scintillator is thus simplified by eliminating the difficulty of precisely determining the appropriate ratio between a primary and a secondary fluorophore in order to obtain optimized radioluminescence radiation and fluorescence decay constant. Therefore, as previously mentioned, in one particular embodiment, the aforementioned hybrid material does not include a secondary fluorophore.

[0023] At the molecular level, the aforementioned plastic scintillator can be considered a pseudo-liquid, as the polymer chains constituting all or part of the polymer matrix are labile and allow a certain degree of freedom of movement to the various components of the plastic scintillator. At the macroscopic level, however, the plastic scintillator retains sufficient mechanical strength for manufacturing a component for scintillation detection.

[0024] The invention is complemented by the following objects and / or features, taken alone or according to any of their technically possible combinations.

[0025] In this description of the invention, verbs such as "include," "incorporate," "include," "contain," and their conjugated forms are open terms and therefore do not preclude the presence of additional element(s) and / or step(s) beyond the initial element(s) and / or step(s) stated after these terms. However, these open terms also encompass a particular embodiment in which only the initial element(s) and / or step(s), to the exclusion of all others, are included; in which case the open term also includes the closed term "consist of," "constitute," "compose of," and their conjugated forms.

[0026] The use of the indefinite article "a" or "an" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of elements or steps, so that the expressions "one or more" or "an or more" can be substituted for it.

[0027] Any reference sign in parentheses in the claims shall not be interpreted as limiting the scope of the invention.

[0028] The expression "according to one or more of the variants described in this description" for a material / element refers in particular to variants concerning the chemical composition and / or proportion of the constituents of that material and any additional chemical species it may contain, and in particular to variants concerning the chemical composition, structure, geometry, spatial arrangement, and / or chemical composition of that element or a constituent sub-element of the element. These variants are, for example, those indicated in the claims.

[0029] Furthermore, unless otherwise stated: The values ​​at the terminals are included within the specified parameter ranges; unless otherwise stated, the margins of uncertainty for the values ​​mentioned are such that the maximum error for the last given figure must be estimated using the rounding convention. For example, for a measurement of 3.5, the margin of error is 3.45–3.54. The temperatures indicated are assumed for atmospheric pressure operation; any mass percentage of a component of the plastic scintillator refers to the total mass of the plastic scintillator, the remainder being the polymer matrix.

[0030] The polymer matrix of the aforementioned hybrid material consists, in whole or in part, of at least one polymer comprising repeating units resulting from the polymerization of monomers or oligomers (which may themselves originate from the polymerization of monomers). The chemical structure of the repeating units is therefore close to the chemical structure of the monomers, the latter having been modified only by the polymerization reaction. In this description, a polymer is a general term that can refer to a homopolymer or a copolymer, namely a polymer that may comprise repeating units with identical or different chemical structures.

[0031] The monomer or oligomer includes, for example, at least one aromatic group (particularly to exploit its photophysical properties), (meth)acrylic (i.e., acrylic or methacrylic), or vinyl group. A polymerizable group may be a group comprising an unsaturated carbon-carbon ethylene double bond, such as, for example, the (meth)acrylic or vinyl group. Furthermore, this polymerizable group must be capable of polymerization via radical polymerization.

[0032] More specifically, at least one monomer can be chosen from styrene, vinyltoluene, vinylxylene, 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, N-vinylcarbazole, methyl (meth)acrylate, (meth)acrylic acid or 2-hydroxyethyl (meth)acrylate, or more generally an alkyl methacrylate whose linear or branched alkyl group has between 1 and 20 carbon atoms.

[0033] Preferably, the monomer is styrene or vinyltoluene in order to form the corresponding homopolymer.

[0034] Advantageously, the monomer can be chosen more specifically from a molecule with particular fluorescence properties, for example 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, N-vinylcarbazole or mixtures thereof.

[0035] According to a particular embodiment, the polymer matrix of the aforementioned hybrid material does not comprise, in whole or in part, at least one polymer comprising repeating units resulting from the polymerization of monomers or oligomers comprising a triacrylate and / or trimethylacrylate group; this excludes from the polymer matrix a polymer such as, for example, TMPTA (ethoxylated trimethylolpropanetriacrylate), in particular ethoxylated TMPTA (15). Advantageously, this makes it possible to exclude a polymer with brittle mechanical properties.

[0036] The polymer matrix may consist entirely or partially (preferably more than 10% by mass of polymer in the polymer matrix) of at least one crosslinked polymer (for example, crosslinked by means of a crosslinking agent) in which polymer chains are linked together by crosslinking bridges, in particular to improve mechanical and / or scintillation properties. The crosslinking agent may be a monomer comprising at least two polymerizable functional groups capable, after polymerization, of forming a bridge between two polymer chains. It may be selected from divinylbenzene, an alkyl diacrylate, or an alkyl dimethacrylate, the hydrogen chain of the latter two containing between 2 and 20 carbon atoms.

[0037] Preferably, the crosslinking agent is 1,4-butanediyl dimethacrylate or divinylbenzene.

[0038] After polymerization of the crosslinked polymer, in addition to the aforementioned repeating units, the resulting copolymer may include repeating units resulting from the polymerization of the crosslinking agent.

[0039] Regarding one of the other main constituents of the aforementioned hybrid material, namely the fluorescent mixture incorporated into the polymer matrix, the hybrid material can comprise 1% to 25% by mass of the incorporated fluorescent mixture, or even 1% to 5% by mass of the incorporated fluorescent mixture relative to the total mass of the hybrid material. Beyond a mass concentration of 25%, exudation may occur, namely a seepage of the fluorescent mixture from the plastic scintillator.

[0040] The mass concentration of the fluorescent mixture incorporated in the hybrid material can be easily calculated by determining the mass of the polymer matrix.

[0041] One method used by those skilled in the art is as follows: the molar concentration of monomers and oligomers in the polymerization medium is known in advance or can be determined by a quantitative measurement method such as UV spectrophotometry. The corresponding mass concentration is then calculated from the molecular weights. Monomers, oligomers, or mixtures thereof form the polymer matrix according to a polymerization yield that can be measured beforehand, but which is generally greater than 95%, even 98%, and most often equal to 100%. Therefore, the mass proportion of monomers and oligomers present in the polymer matrix is ​​equivalent to this reaction yield multiplied by the previously determined mass concentration.A person skilled in the art can therefore easily use their general knowledge to convert a mass concentration into a molar concentration for all the constituents of the hybrid material.

[0042] The mass or molar percentages of the incorporated fluorescent mixture, the main primary fluorophore, the additional primary fluorophore, the secondary fluorophore, or an additional compound can be determined a posteriori in the hybrid material by an analytical technique such as, for example, solid-state Nuclear Magnetic Resonance (NMR). Another technique involves dissolving the plastic scintillator in dichloromethane, precipitating the polymer constituting the polymeric matrix in methanol, filtering the resulting mixture to recover the molecule whose concentration is to be measured, and then quantifying it by elemental analysis with detection of a specific atom constituting that molecule.

[0043] The incorporation of the fluorescent mixture into the polymer matrix can be carried out in several ways. In particular, at least one fluorescent molecule selected from the main primary fluorophore, the additional primary fluorophore, or mixtures thereof, can be incorporated into the polymer matrix by dispersion or by grafting this molecule into the polymer matrix. In the case of grafting, the fluorescent molecule (generally the additional primary fluorophore) is covalently bonded to the polymer matrix. This covalent bond is formed, for example, during the polymerization of the polymer matrix, provided the fluorescent molecule contains at least one polymerizable functional group.

[0044] Optionally, the aforementioned hybrid material may contain one or more substances that do not significantly impact the plastic scintillation measurement with this hybrid material or that enhance some of its properties. Like the incorporated fluorescent mixture, these substances are generally dispersed homogeneously or non-homogeneously within the hybrid material.

[0045] The decay constant of the aforementioned hybrid material is conferred by that of the incorporated fluorescent mixture. Thus, the incorporated fluorescent mixture, and therefore the hybrid material, can have a fluorescence decay constant between 10 ns and 90 ns, or even between 15 ns and 80 ns, advantageously between 30 ns and 80 ns, particularly between 25 ns and 75 ns, more particularly between 28 ns and 70 ns.

[0046] The judiciously chosen concentration of main primary fluorophore and the complementary concentration of additional primary fluorophore give the incorporated fluorescent mixture, and therefore the hybrid material, a fluorescence decay constant that can thus be chosen.

[0047] The incorporated fluorescent mixture comprises i) 95.6% to 99.1 mol% of the main primary fluorophore consisting of naphthalene and ii) 0.9% to 4.4 mol% of the additional primary fluorophore. Within this concentration range, the fluorescence decay constant of the aforementioned hybrid material can range from 25 ns to 75 ns, more specifically from 28 ns to 70 ns.

[0048] These preferred primary fluorophore concentration ranges can therefore impart an increasingly high fluorescence decay constant to the hybrid material. Such a hybrid material can then be advantageously incorporated into a hybrid plastic scintillator compartment, possibly combined with a fast plastic scintillator compartment in a phoswich-type plastic scintillation detection device to improve discrimination between beta particles and gamma radiation. Furthermore, they represent a good compromise between scintillation efficiency and the tunability of the aforementioned hybrid material.

[0049] For example, varying molar concentrations of the main primary fluorophore in the incorporated fluorescent mixture (the remainder of the mixture being made up of the additional primary fluorophore) may eventually give the hybrid material the following fluorescence decay constants: molar concentration of 86%: 15 ns (not subject to the protection requested); molar concentration of 95.6%: 28 ns; molar concentration of 96%: 35 ns; molar concentration of 99%: 80 ns; molar concentration of 100%: 90 ns (not subject to the protection requested).

[0050] The additional primary fluorophore has a fluorescence decay constant (usually designated "tau") between 1 ns and 10 ns, has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 250 nm and 340 nm and between 330 nm and 380 nm, and whose fluorescence quantum yield in a nonpolar solvent is preferentially between 0.5 and 1.

[0051] In this description, the centroid refers to the wavelength at the midpoint of the full width at half maximum (FWHM) of the largest amplitude band of the radiation under consideration. A light absorption spectrum can be measured with a UV / visible spectrophotometer, and a fluorescence emission spectrum with a spectrofluorimeter.

[0052] The fluorescence decay constant corresponds to the variation over time of the photoluminescence intensity. It is measured by time-resolved single photon counting; as described for example in the document "M. Wahl, "Time-Correlated Single Photon Counting", M. Wahl, PicoQuant company technical note, 2014" [reference 4], available online at the following Internet address: "https: / / www.picoquant.com / images / uploads / page / files / 7253 / technote_tcspc.pdf", as well as the book "DV O'Connor, D. Phillips, "Time Correlated Single Photon Counting", Academic Press, New York, 1984, pages 25 to 34" [reference 5].

[0053] The quantum efficiency of fluorescence corresponds to the proportion of luminescent photons emitted per photons absorbed by the hybrid material. Preferably, its value is obtained using an absolute measurement method, i.e., one that does not involve a third compound or a calibration function. For example, it is measured with an integrating sphere as the module of a spectrofluorimeter. For a measurement of the absolute value, see Rohwer, LS, Martin, JE; "Measuring the absolute quantum efficiency of luminescent materials", J. Lumin. 2005, 115, pages 77-90. » [reference 6]).

[0054] The fluorescence quantum yield can also be obtained using a relative measurement method based on the following principle: knowing the absolute fluorescence quantum yield of a third compound, the absolute measurement value is obtained by a simple proportion. For example, without an integrating sphere, the fluorescence quantum yield can be determined by relative measurement of the sample (a reference solution of quinine sulfate as the third compound is used, for example, in the document). « Velapoli, RA; Mielenz, KD, "A Fluorescence Standard Reference Material: Quinine Sulfate Dihydrate", Appl. Opt., 1981, 20, 1718 . » [reference 7] available online at the following Internet address: https: / / www.nist.gov / sites / default / files / documents / srm / SP260-64.PDF).

[0055] Generally, the values ​​obtained by the absolute and relative measurement methods are identical or similar.

[0056] Advantageously, the additional primary fluorophore can have a fluorescence emission spectrum whose centroid is at a wavelength between 355 nm and 365 nm, typically centered around 360 nm, so that the interaction effect is optimal with the secondary fluorophore.

[0057] Time-resolved single-photon counting is a spectroscopic technique used to measure the fluorescence decay constant of photoluminescent compounds or mixtures thereof. It involves exciting a fluorophore or fluorescent mixture with a rapidly decaying light beam (relative to the reflected luminescent radiation being observed), and then observing the resulting photoluminescence using a monochromator coupled to a photomultiplier tube. The aforementioned hybrid material is specifically excited at a low frequency (typically up to 1 MHz) to avoid stacking scintillation pulses.

[0058] Preferably, the additional primary fluorophore is chosen from at least one compound such as: an oxazole (such as, for example, 2,5-diphenyloxazole (PPO)); and / or a polycyclic aromatic compound that is hydrogen-based (i.e., heteroatom-free) comprising 3 to 6 phenyl rings, at least one of which may include at least one substituent in the ortho, meta, or preferably para position (for example, a linear or branched R alkyl substituent, preferably saturated, preferably comprising 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms), such as, for example, [ para ]-terphenyl (pTP), the [ meta ]-terphenyl (mTP), the [para]- quaterphenyl, biphenyl, 1-vinylbiphenyl, 2-vinylbiphenyl, 4-isopropylbiphenyl, [para]- sexiphenyl), or mixtures thereof; and / or an oxadiazole, such as, for example, 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole (PBD), 2-(4' -t-butylphenyl)-5-(4"-biphenylyl)-1,3,4-oxadiazole (Butyl-PBD) or mixtures thereof; and / or an anthracene compound such as anthracene, 9-anthracenyl methacrylate, or mixtures thereof; and / or a naphthalene substituted with a vinyl group (such as 1-vinylnaphthalene or 2-vinylnaphthalene), a naphthalene substituted with an R substituent as defined above (such as, for example, 1-methylnaphthalene), or mixtures thereof; and / or a carbazole such as, for example, N -vinylcarbazole, the N -ethylcarbazole, the N -(2-ethylhexyl)carbazole or mixtures thereof; and / or tetraphenylbutadiene.

[0059] More specifically, the additional primary fluorophore is 2,5-diphenyloxazole (PPO), the [para]- terphenyl (pTP), or even the [ meta ]-terphenyl (mTP) or mixtures thereof.

[0060] As previously mentioned, the additional primary fluorophore can be covalently linked to the polymer matrix, for example, via the polymerization of a vinyl, allylic, acrylic, or methacrylic group carried by the additional primary fluorophore. Examples include 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, and N -vinylcarbazole can be used to be covalently bonded to form a copolymer with the polymer matrix.

[0061] The incorporated fluorescent mixture may also include a secondary fluorophore. The secondary fluorophore further improves the detection of radioluminescent radiation.

[0062] The mass concentration of the secondary fluorophore relative to the mass of the hybrid material can be between 0.002% and 0.5% by mass, preferably between 0.01% and 0.2% by mass, and even more preferably between 0.01% and 0.1% by mass.

[0063] As an example, the secondary fluorophore can be chosen from 1,4-di[2(5-phenyloxazolyl)]benzene, 1,4-bis-(2-methylstyryl)benzene, 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene, 9,10-diphenylanthracene, or mixtures thereof. The polymer matrix then comprises, relative to the mass of the hybrid material, 0.002% to 0.2% by mass of the secondary fluorophore.

[0064] According to a first embodiment, the secondary fluorophore can be chosen such that it has a light absorption spectrum and a fluorescence emission spectrum whose centroid is at wavelengths between 330 nm and 380 nm and between 405 nm and 460 nm, respectively, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1. The secondary fluorophore can thus be chosen from 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP), 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene (dimethylPOPOP), bis-methylstyrylbenzene (bis-MSB), 9,10-diphenylanthracene (9,10-DPA), or mixtures thereof. The molecular structures of these secondary fluorophores are illustrated below.

[0065] According to a second embodiment, the secondary fluorophore can be selected such that it has a light absorption spectrum and a fluorescence emission spectrum whose centroid is at wavelengths between 330 nm and 380 nm and between 460 nm and 550 nm, respectively, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1. The secondary fluorophore can then be selected from coumarin 6, coumarin 7, coumarin 30, coumarin 102, coumarin 151, coumarin 314, coumarin 334, 3-hydroxyflavone, or mixtures thereof. The molecular structures of these secondary fluorophores are illustrated below.

[0066] According to a third embodiment, the secondary fluorophore can be chosen such that it has a light absorption spectrum and a fluorescence emission spectrum whose centroid is at wavelengths between 330 nm and 380 nm and between 550 nm and 630 nm, respectively, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1. The secondary fluorophore can then be chosen from Nile red, rhodamine B or one of its salts, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H -pyran (DCM), pyrromethene 580, any molecule of the type N -alkyl or N -alkyl or N -aryl-perylenediimide (such as for example the N,N '-bis(2,5-di-tert-butylphenyl)-3,4,9,10-perylenedicarboximide). The molecular structures of these secondary fluorophores are illustrated below.

[0067] Not being subject to the protection sought, a manufacturing process by polymerization, via a polymerization medium, of the aforementioned hybrid material which can be as defined in this description, is now described, in particular according to one or more of the variants described for this material.

[0068] The manufacturing process for a hybrid material by polymerization comprises the following successive steps: a) have a polymerization medium comprising: monomers, oligomers or mixtures thereof intended to form at least one polymer constituting the polymeric matrix which may be as defined in this description, in particular according to one or more of the variants described for this polymeric matrix;a liquid fluorescent mixture comprising, in molar concentration relative to the total number of moles of primary fluorophore in the liquid fluorescent mixture, i) 80% (more precisely 80.0%) to 99.6 mol% of a main primary fluorophore consisting of naphthalene and ii) 0.4% to 20 mol% (more precisely 20.0%) of an additional primary fluorophore having a centroid of light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent between 0.2 and 1, preferably between 0.5 and 1; b) polymerize the polymerization medium to obtain the hybrid material.

[0069] During step b) of polymerization of a polymer precursor (i.e. a precursor such as the aforementioned monomers and / or oligomers), the main and supplementary primary fluorophores, as well as any other compound present in the polymerization medium, are generally trapped and distributed homogeneously in the forming polymer matrix.

[0070] Therefore, in this description, the "liquid fluorescent mixture" is the fluorescent mixture comprising the main primary fluorophore and the additional primary fluorophore and which is contained in the polymerization medium before carrying out step b).

[0071] The "incorporated fluorescent mixture" refers to the fluorescent mixture comprising the main primary fluorophore and the additional primary fluorophore and which is incorporated into the hybrid material after step b) of polymerization, for example by grafting or dispersion.

[0072] The "fluorescent extrusion mix" refers to the fluorescent mix comprising the main primary fluorophore and the additional primary fluorophore which is contained in the extrusion mix which also contains polymerized ingredients intended to form a polymeric matrix.

[0073] The polymerization medium generally does not contain a solvent. The manufacturing process is then a so-called "bulk polymerization" process.

[0074] However, as an option, the polymerization medium may also include a polymerization solvent. The manufacturing process is then generally carried out under solvent reflux. The solvent for the polymerization medium can be chosen from xylene, chloroform, dichloromethane, chlorobenzene, benzene, tetrachloromethane, or mixtures thereof.

[0075] Monomers or oligomers may include at least one aromatic, (meth)acrylic, or vinyl group. At least one monomer may be selected from styrene, vinyltoluene, vinylxylene, 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, N -vinylcarbazole, methyl (meth)acrylate, (meth)acrylic acid or 2-hydroxyethyl (meth)acrylate.

[0076] The polymerization medium can include 1% by mass to 25% by mass (or even 1% by mass to 5% by mass) of the liquid fluorescent mixture.

[0077] The polymerization medium may further include at least one chemical species intended to be incorporated into the hybrid material to impart or enhance particular properties (e.g., a secondary fluorophore), and / or at least one species intended to be consumed or modified during step b) of polymerization (e.g., a crosslinking agent, a polymerization initiator).

[0078] The polymerization medium may include: a secondary fluorophore, typically at a mass concentration of between 0.002% and 0.5% by mass, or even 0.002% by mass to 0.2% by mass; and / or a crosslinking agent, typically at a mass concentration of between 0.1% and 20% (more precisely 20.0%) by mass, or even 0.001% by mass to 1% by mass; and / or a polymerization initiator, typically at a concentration of 0.001% by mass to 1% by mass.

[0079] The additional primary fluorophore, secondary fluorophore and / or crosslinking agent may also be as defined according to one or more of the variants described in this description.

[0080] The polymerization reaction according to step b) can be carried out under the conditions usually employed by a person skilled in the art.

[0081] Thus, it can be started with a polymerization initiator, specifically a photoinitiator to initiate radical polymerization. Preferably, the photoinitiator is not a UV-activated photoinitiator, such as TPO. A UV photoinitiator can produce residual compounds or alter other compounds in the plastic scintillation material, resulting in photobleaching of this material, which is detrimental to good scintillation yield.

[0082] Preferably, to best avoid such a problem, the photoinitiator used here is activatable under visible light. For example, as indicated in patent application WO 2013076281 [reference 8], the polymerization initiator can be chosen from a peroxide compound (e.g., benzoyl peroxide), a nitrile compound (e.g., azo(bis)isobutyronitrile (AIBN)), or mixtures thereof.

[0083] When the polymerization reaction is carried out, particularly with methacrylate monomers, it can be induced by heating the polymerization medium to a suitable temperature (generally between 40 °C and 140 °C), or by doping the polymerization medium with 2,2-dimethoxy-2-phenylacetophenone as a polymerization initiator and then irradiating it with UV light (for example, at a wavelength of 355 nm). The polymerization reaction in the presence of styrenic monomers can be induced thermally, typically by heating between 40 °C and 140 °C.

[0084] The aforementioned manufacturing process of the hybrid material by polymerization may be such that, during step b) of polymerization, the polymerization medium is heated to a polymerization temperature between 100 °C and 140 °C (for a sufficient time for polymerization to be complete, generally for 24 hours), then cooled at a rate of 10 °C to 20 °C per day (generally to reach room temperature, typically 20 °C) until the hybrid material is obtained.

[0085] For example, the polymerization medium can be heated for 24 hours at 140 °C, then cooled at a rate of 20 °C per day until it returns to 20 °C.

[0086] Steps a) and b) of the manufacturing process by polymerization via a polymerization medium can be carried out in a mold in order to obtain a part as defined in this description, or a rough draft of this part.

[0087] The manufacturing process by polymerization via a polymerization medium may further include a step (c) in which the hybrid material or the blank of the part is machined to obtain the part as defined in this description. This machining step consists, for example, of grinding the faces (e.g., on a lathe) and then polishing them.

[0088] The aforementioned hybrid material is obtained or is capable of being obtained by the manufacturing process of polymerizing a hybrid material via a polymerization medium, in particular according to one or more of the variants described for this process.

[0089] Not being subject to the protection requested, a part for detection by plastic scintillation may include a hybrid material which may be as defined according to one or more of the variants described in this description for this material.

[0090] In general, the part for plastic scintillation detection is thus composed in whole or in part of a hybrid material comprising: a polymeric matrix; and, a fluorescent mixture incorporated in the polymeric matrix and comprising in molar concentration relative to the total number of moles of primary fluorophore in the incorporated fluorescent mixture i) 95.6% to 99.1 mol% of a main primary fluorophore consisting of naphthalene and ii) 0.9% to 4.4 mol% of an additional primary fluorophore whose centroid of the light absorption spectrum and fluorescence emission spectrum have wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm (or even between 355 nm and 365 nm), respectively, the fluorescence decay constant is between 1 ns and 10 ns, and the fluorescence quantum yield in a nonpolar solvent is between 0.2 and 1 (or even between 0.5 and 1).

[0091] This part can be a unit (such as, for example, an optical fiber) or a subunit of a device for detection by plastic scintillation (for example, the hybrid compartment of a phoswich-type detector).

[0092] The polymer matrix of the hybrid material composing all or part of the part may be composed in whole or in part of at least one polymer comprising repeating units resulting from the polymerization of monomers comprising at least one aromatic, (meth)acrylic or vinylic group and / or it may be composed in whole or in part of at least one cross-linked polymer.

[0093] At least one monomer intended to form the polymer matrix is ​​chosen from styrene, vinyltoluene, vinylxylene, 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, the N-vinylcarbazole, methyl (meth)acrylate, (meth)acrylic acid or 2-hydroxyethyl (meth)acrylate. Preferably, the monomer is styrene or vinyltoluene.

[0094] The aforementioned component for detection by plastic scintillation can be presented in the following variants, possibly combined: the hybrid material comprises 1 wt% to 25 wt% (or even 1 wt% to 5 wt%) of the incorporated fluorescent mixture, and / or; the incorporated fluorescent mixture comprises i) 95.6 wt% to 99.1 wt% of the main primary fluorophore consisting of naphthalene and ii) 0.9 wt% to 4.4 wt% of the additional primary fluorophore. The additional primary fluorophore is covalently bonded to the polymer matrix, and / or; the additional primary fluorophore is selected from 2,5-diphenyloxazole (PPO), the [ para ]-terphenyl (pTP), the [ meta]-terphenyl (mTP), biphenyl, 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole (PBD), 2-(4'- t- butylphenyl)-5-(4"-biphenylyl)-1,3,4-oxiadiazole (Butyl-PBD), anthracene, the [ para ]-quaterphenyl, tetraphenylbutadiene, the N -ethylcarbazole, the N -(2-ethylhexyl)carbazole, 4-isopropylbiphenyl, [para]- sexiphenyl, 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, the N -vinylcarbazole, 9-anthracenyl methacrylate or mixtures thereof; the additional primary fluorophore preferably being 2,5-diphenyloxazole (PPO), the [ para ]-terphenyl (pTP), or even the [meta]- terphenyl (mTP) or mixtures thereof.

[0095] The incorporated fluorescent mixture of the hybrid material of the part may further include a secondary fluorophore, for example at a mass concentration relative to the mass of the hybrid material which is between 0.002% and 0.5% by mass, or even 0.01% by mass to 0.2% by mass of the secondary fluorophore.

[0096] The primary fluorophore can be selected from 1,4-di[2(5-phenyloxazolyl)]benzene, 1,4-bis-(2-methylstyryl)-benzene, 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene, 9,10-diphenylanthracene or mixtures thereof.

[0097] According to a first embodiment, the secondary fluorophore has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 405 nm and 460 nm, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1.

[0098] In this case, the secondary fluorophore can be chosen from 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP), 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene (dimethylPOPOP), bis-methylstyrylbenzene (bis-MSB), 9,10-diphenylanthracene (9,10-DPA) or mixtures thereof.

[0099] According to a second embodiment, the secondary fluorophore has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 460 nm and 550 nm, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1.

[0100] In this case, the secondary fluorophore can be chosen from coumarin 6, coumarin 7, coumarin 30, coumarin 102, coumarin 151, coumarin 314, coumarin 334, 3-hydroxyflavone or mixtures thereof.

[0101] According to a third embodiment, the secondary fluorophore has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 550 nm and 630 nm, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1.

[0102] In this case, the secondary fluorophore can be chosen from Nile red, rhodamine B or one of its salts, 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H -pyrane, pyrromethene 580, or a N -alkyl or N -aryl-perylenediimide.

[0103] By virtue of the possibility of varying the relative proportion between the main primary fluorophore and the additional primary fluorophore, the hybrid material (and therefore the part for detection by plastic scintillation) can have a fluorescence decay constant between 10 ns and 90 ns (or even between 15 ns and 80 ns); particularly between 25 ns and 75 ns, more particularly between 28 ns and 70 ns.

[0104] The piece can have a wide variety of shapes, for example a parallelepiped or cylindrical shape.

[0105] The parallelepiped-shaped part is, for example, a plastic scintillator compartment suitable for incorporation into a device for detection by plastic scintillation.

[0106] When the part has a cylindrical shape, and is for example part of the composition of a plastic scintillator pillar, it can have a square or rectangular cross-section.

[0107] When the cylindrical part is, for example, a scintillating optical fiber (in which case the hybrid material includes a polymer matrix consisting entirely or partly of at least one polymer that is not cross-linked), it can have a circular, elliptical, or hexagonal cross-section.

[0108] An optical fiber is a waveguide that exploits the refractive properties of light. It typically consists of a core surrounded by a cladding. The fiber core has a slightly higher refractive index (a difference of a few thousandths) than the cladding. Therefore, the light is completely reflected multiple times at the interface between the inner fiber material of the core and the cladding material by total internal reflection.

[0109] The scintillating optical fiber as part 10 may comprise a polymer fiber 11 composed in whole or in part of the hybrid material and provided or not with a sheath 12 covering the polymer fiber and composed in whole or in part of an optical fiber sheathing material having a refractive index lower than that of the hybrid material, the hybrid material comprising a polymer matrix consisting in whole or in part of at least one polymer which is not crosslinked.

[0110] Several scintillating optical fibers can be joined together into a fiber bundle.

[0111] The presence of a cladding is not mandatory. For example, when the component is intended to detect an alpha particle, the scintillating optical fiber consists solely of an internal polymer fiber without a cladding to prevent the energy of the incident radiation from being mostly absorbed by the cladding.

[0112] However, scintillating optical fiber most often includes a cladding whose sheathing material is a material commonly used for optical fibers, particularly scintillating fibers. For example, the sheathing material is chosen from poly(methyl methacrylate), poly(benzyl methacrylate), poly(trifluoromethyl methacrylate), poly(trifluoroethyl methacrylate), or mixtures thereof.

[0113] Not being covered by the protection sought, a manufacturing process by extrusion of a part for plastic scintillation detection, composed in whole or in part of the aforementioned hybrid material, the part being as defined according to one or more of the variants described herein, is now described. The process comprises the following successive steps: (a') have an extrusion mixture comprising: polymerized ingredients intended to form a polymer matrix as defined in this description, in particular according to one or more of the variants described, except where the polymer matrix is ​​made up wholly or partly (preferably more than 10% by mass of polymer in the polymer matrix) of at least one crosslinked polymer; a fluorescent extrusion mixture comprising, in molar concentration relative to the total number of moles of primary fluorophore in the fluorescent extrusion mixture: (i) 95.6% to 99.1% molar of a principal primary fluorophore made of naphthalene;and ii) 0.9% to 4.4 mol% of an additional primary fluorophore whose light absorption spectrum centroid and fluorescence emission spectrum centroid have wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, the fluorescence decay constant is between 1 ns and 10 ns, and the fluorescence quantum yield in a nonpolar solvent is between 0.2 and 1; b') under an extrusion atmosphere at an extrusion temperature between 170 °C and 200 °C, extrude the extrusion mixture through a die to obtain the part composed in whole or in part of a hybrid material.

[0114] An extrusion manufacturing process is essentially a process for transforming polymerized ingredients which, once softened or molten by heat, are continuously forced through a die that gives its geometry to the polymer-based profile obtained at the end of the process. The extrusion process is well known to those skilled in the art: it is described, for example, in the document "Techniques de l'ingénieur, Extrusion - extrusion monovis (part 1), Reference AM3650, 2002 publication" [reference 9].

[0115] The polymerized ingredients that can be used are formed from one or more polymers that exhibit thermal stability such that the polymer is not degraded at the temperature required for extrusion, which depends on the glass transition temperature. Their chemical composition is identical to that of the polymer matrix.

[0116] Polymerized ingredients are usually in solid form, particularly in the form of granules.

[0117] The extrusion step b') can be carried out using an extruder (for example, a single-screw, twin-screw, or multi-screw extruder) or a co-mixer. Typically, the die is positioned at the extruder outlet.

[0118] The extrusion atmosphere can be chemically inert with respect to the extrusion mixture. Such an atmosphere limits or prevents the oxidation of the resulting polymer matrix. It may contain, for example, nitrogen or a noble gas, such as argon.

[0119] Typically, the extrusion process is carried out at an extrusion temperature below 218 °C, which is the evaporation temperature of naphthalene at atmospheric pressure, but at a temperature high enough to soften or melt the polymerized ingredients, for example at an extrusion temperature between 170 °C and 200 °C.

[0120] The extrusion step b') can be carried out using an extruder (for example single-screw, twin-screw or multi-screw type) or a co-malaxer.

[0121] Not being covered by the protection sought, a manufacturing process by polymerization of a part for plastic scintillation detection, composed in whole or in part of the aforementioned hybrid material, the part being as defined according to one or more of the variants described herein, is now described. This process comprises at least one polymerization via a polymerization medium according to the following successive steps: a) in a first mold, have a first polymerization medium comprising: monomers, oligomers or mixtures thereof intended to form at least one polymer constituting a polymeric matrix as defined according to one or more of the variants described in this description (in particular the case where the polymeric matrix is ​​made up in whole or in part of at least one crosslinked polymer); a liquid fluorescent mixture comprising in molar concentration relative to the total number of moles of primary fluorophore in the liquid fluorescent mixture: i) 95.6% to 99.1% molar of a principal primary fluorophore made of naphthalene;and ii) 0.9% to 4.4 mol% of an additional primary fluorophore whose light absorption spectrum centroid and fluorescence emission spectrum centroid have wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, the fluorescence decay constant is between 1 ns and 10 ns, and the fluorescence quantum yield in a nonpolar solvent is between 0.2 and 1; b) polymerize the first polymerization medium to directly obtain the part or a blank of the part which is then modified (e.g. machined, in particular by drawing the blank) to obtain the part.

[0122] In the process of manufacturing a part by polymerization, the fluorescent mixture is liquid, because it is mixed in the first polymerization medium with monomers and / or oligomers.

[0123] The internal volume of the mold can be parallelepiped or cylindrical. The cylindrical shape can have a circular, elliptical, hexagonal, square, or rectangular cross-section.

[0124] When the internal volume of the mold has a parallelepiped shape, the manufacturing process by polymerization can such that the parallelepiped-shaped part obtained at the end of step b) is a plastic scintillator compartment as defined in this description and suitable for incorporation into a device for detection by plastic scintillation.

[0125] In this case, the parallelepiped-shaped plastic scintillator compartment can be obtained directly at the end of the manufacturing process by polymerization, after an optional rectification step if necessary.

[0126] When the internal volume of the mold has a cylindrical shape, the manufacturing process by polymerization can be such that the part is a scintillating optical fiber 10 without a cladding which can be as defined in this description according to one or more of its variants, such that a cylindrical bar as a blank of the part is obtained at the end of step b), the process comprising the following additional step carried out after step b) of polymerization: c) in a fiber-drawing tower, soften by heating and then draw the blank of the part in order to obtain a polymer fiber 11 composed in whole or in part of the hybrid material as a scintillating optical fiber 10 without a cladding.

[0127] Alternatively, when the internal volume of the mold has a cylindrical shape, the polymerization manufacturing process can be such that the part is a scintillating optical fiber 10 provided with a sheath 12 which can be as defined in this description according to one or more of its variants, such that a cylindrical bar as the first roughing of the part is obtained at the end of step b), the process comprising the following additional step carried out after step b): b1) place the first blank of the part in a second cylindrical mold, then fill the free volume delimited by the inner face of the second cylindrical mold and the outer face of the first blank of the part with a second polymerization medium comprising a precursor of a sheathing material for optical fiber for which the refractive index of the sheathing material is lower than that of the hybrid material; b2) polymerize the second polymerization medium in order to form the sheathing material which covers the first blank of the part, in order to obtain a second blank of the part (constituting a preform); (c) in a fiber-pulling tower, soften by heating and then stretch the second blank of the part in order to obtain, as scintillating optical fiber 10 provided with a sheath 12, a polymer fiber 11 composed in whole or in part of the hybrid material and provided with the sheath 12 covering the polymer fiber 11.

[0128] In both of these alternatives, the internal volume of the cylindrical mold has, for example, a circular cross-section. The mold can then have an internal diameter ranging from 2 cm to 10 cm (typically 5 cm) and / or a longitudinal length ranging from 10 cm to 100 cm (typically 50 cm). These dimensions generally correspond to those of the cylindrical bar as a preform or blank for the part.

[0129] The precursor of the sheathing material is chosen for example from methyl methacrylate, benzyl methacrylate, trifluoromethyl methacrylate, trifluoroethyl methacrylate or mixtures thereof.

[0130] The blank or preform is generally placed vertically on the fiber-laying tower. At the end of step c), the scintillating optical fiber, with or without a cladding, is most often recovered by gravity spinning.

[0131] During polymerization step b) and / or b1), the initial polymerization medium may be heated to a first polymerization temperature between 100 °C and 140 °C (e.g., for a period of 12 to 24 hours, including one day at 140 °C), and then cooled by decreasing the polymerization temperature by 10 °C to 20 °C per day until the part or part blank is obtained. Cooling is generally continued until the ambient temperature of 20 °C is reached.

[0132] During polymerization step b2), the second polymerization medium can be heated to a second polymerization temperature of between 50 °C and 70 °C (for example, for 8 to 10 days, including 10 days at 60 °C), and then cooled by decreasing the polymerization temperature by 10 °C to 20 °C per day until the part or part blank is obtained. Cooling is generally continued until the ambient temperature of 25 °C is reached.

[0133] The heating operation to soften can be carried out during step c) at a temperature between 150 °C and 190 °C.

[0134] The rough part can be ground just before step c) of drawing. For example, a cylindrical bar is ground by cutting off its top and bottom sections over a short length. The top face of a parallelepiped-shaped part, that is, the face that comes into slight contact with the ambient air, can also be ground by cutting off the top section over a short length and then polishing it.

[0135] At the end of the polymerization manufacturing process, the scintillating optical fiber can be such that: the diameter of the polymer fiber 11 is between 50 µm and 1 mm, and / or; the thickness of the cladding 12 is between 1 µm and 20 µm, and / or; the length of the scintillating optical fiber is between 0.1 and 2 km.

[0136] The first polymerization medium and / or the second polymerization medium may include a polymerization solvent chosen for example from xylene, chloroform, dichloromethane, chlorobenzene, benzene, tetrachloromethane or mixtures thereof.

[0137] Regarding the manufacturing process of a part by extrusion or the manufacturing process of a part by polymerization respectively, the fluorescent mixture for extrusion or the liquid fluorescent mixture can be such that: the additional primary fluorophore has a fluorescence quantum yield in a nonpolar solvent between 0.5 and 1, and / or; it comprises a secondary fluorophore as defined in this description, including one or more of the variants described.

[0138] Not being subject to the protection sought, a device for detection by plastic scintillation comprising a part for detection by plastic scintillation (which may be as defined according to one or more of the variants described in this description) as a hybrid plastic scintillator element, the part generally being composed in whole or in part of the aforementioned hybrid material comprises: a polymeric matrix; and, a fluorescent mixture incorporated in the polymeric matrix and comprising in molar concentration relative to the total number of moles of primary fluorophore in the incorporated fluorescent mixture: i) 95.6% to 99.1 mol% of a main primary fluorophore consisting of naphthalene; and ii) 0.9% to 4.4 mol% of an additional primary fluorophore having a centroid of the light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent between 0.2 and 1 (or even between 0.5 and 1);the part being coupled to an electronic acquisition module such that the module is capable of collecting the radioluminescent radiation emitted by the part when the latter is brought into contact with ionizing radiation or an ionizing particle. ;

[0139] The polymer matrix of the hybrid material composing all or part of the part may be composed in whole or in part of at least one polymer comprising repeating units resulting from the polymerization of monomers comprising at least one aromatic, (meth)acrylic or vinylic group and / or it may be composed in whole or in part of at least one cross-linked polymer.

[0140] At least one monomer intended to form the polymer matrix may be chosen from styrene, vinyltoluene, vinylxylene, 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, the N-vinylcarbazole, methyl (meth)acrylate, (meth)acrylic acid or 2-hydroxyethyl (meth)acrylate. Preferably, the monomer is styrene or vinyltoluene.

[0141] The aforementioned hybrid material, which makes up all or part of the component integrated into the device for detection by plastic scintillation, can be presented in the following variants, possibly combined: the hybrid material comprises 1 wt% to 25 wt% (or even 1 wt% to 5 wt%) of the incorporated fluorescent mixture, and / or; the additional primary fluorophore is covalently linked to the polymer matrix, and / or; the additional primary fluorophore is selected from 2,5-diphenyloxazole (PPO), the [ para ]-terphenyl (pTP), the [meta] -terphenyl (mTP), biphenyl, 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole (PBD), 2-(4' -t- butylphenyl)-5-(4"-biphenylyl)-1,3,4-oxiadiazole (Butyl-PBD), anthracene, the [ para]-quaterphenyl, tetraphenylbutadiene, the N -ethylcarbazole, the N -(2-ethylhexyl)carbazole, 4-isopropylbiphenyl, [para]- sexiphenyl, 1-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 1-methylnaphthalene, the N -vinylcarbazole, 9-anthracenyl methacrylate or mixtures thereof; the additional primary fluorophore preferably being 2,5-diphenyloxazole (PPO), the [ para ]-terphenyl (pTP), or even the [meta]- terphenyl (mTP) or mixtures thereof.

[0142] The incorporated fluorescent mixture of the hybrid material of the part may further include a secondary fluorophore, for example at a mass concentration relative to the mass of the hybrid material which is between 0.002% and 0.5% by mass, or even 0.01% by mass to 0.2% by mass of the secondary fluorophore.

[0143] The primary fluorophore can be selected from 1,4-di[2(5-phenyloxazolyl)]benzene, 1,4-bis-(2-methylstyryl)-benzene, 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene, 9,10-diphenylanthracene or mixtures thereof.

[0144] According to a first embodiment, the secondary fluorophore has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 405 nm and 460 nm, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1.

[0145] In this case, the secondary fluorophore can be chosen from 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP), 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene (dimethylPOPOP), bis-methylstyrylbenzene (bis-MSB), 9,10-diphenylanthracene (9,10-DPA) or mixtures thereof.

[0146] According to a second embodiment, the secondary fluorophore has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 460 nm and 550 nm, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1.

[0147] In this case, the secondary fluorophore can be chosen from coumarin 6, coumarin 7, coumarin 30, coumarin 102, coumarin 151, coumarin 314, coumarin 334, 3-hydroxyflavone or mixtures thereof.

[0148] According to a third embodiment, the secondary fluorophore has a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 550 nm and 630 nm, and whose fluorescence quantum yield in a nonpolar solvent is between 0.5 and 1.

[0149] In this case, the secondary fluorophore can be chosen from Nile red, rhodamine B or one of its salts, 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H -pyrane, pyrromethene 580, or a N -alkyl or N -aryl-perylenediimide.

[0150] By virtue of the possibility of varying the relative proportion between the main primary fluorophore and the additional primary fluorophore, the hybrid material (and therefore the part for detection by plastic scintillation and the device which integrates it) can have a fluorescence decay constant between 10 ns and 90 ns (or even between 15 ns and 80 ns); particularly between 25 ns and 75 ns, more particularly between 28 ns and 70 ns.

[0151] The part of the device can have a wide variety of shapes, for example a parallelepiped or cylindrical shape.

[0152] The parallelepiped-shaped part is, for example, a plastic scintillator compartment suitable for incorporation into a device for detection by plastic scintillation.

[0153] When the part has a cylindrical shape, and is for example part of the composition of a plastic scintillator pillar, it can have a square or rectangular cross-section.

[0154] When the cylindrical part is, for example, a scintillating optical fiber (in which case the hybrid material includes a polymer matrix consisting entirely or partly of at least one polymer that is not cross-linked), it can have a circular, elliptical, or hexagonal cross-section.

[0155] The scintillating optical fiber as part 10 may comprise a polymer fiber 11 composed in whole or in part of the hybrid material and provided or not with a sheath 12 covering the polymer fiber and composed in whole or in part of an optical fiber sheathing material having a refractive index lower than that of the hybrid material, the hybrid material comprising a polymer matrix consisting in whole or in part of at least one polymer which is not crosslinked.

[0156] Several scintillating optical fibers can be joined together into a fiber bundle.

[0157] The presence of a cladding is not mandatory. For example, when the component is intended to detect an alpha particle, the scintillating optical fiber consists solely of an internal polymer fiber without a cladding to prevent the energy of the incident radiation from being mostly absorbed by the cladding.

[0158] However, scintillating optical fiber most often includes a cladding whose sheathing material is a material commonly used for optical fibers, particularly scintillating fibers. For example, the sheathing material is chosen from poly(methyl methacrylate), poly(benzyl methacrylate), poly(trifluoromethyl methacrylate), poly(trifluoroethyl methacrylate), or mixtures thereof.

[0159] The coupling between the part as a plastic scintillator element and the acquisition module is generally achieved by bringing the acquisition module into contact with a portion of the part from which the radioluminescent radiation emerges from the part.

[0160] According to a first embodiment, the device for detection by plastic scintillation is such that the hybrid plastic scintillator element is a first hybrid plastic scintillator element 1, the device further comprising a second fast plastic scintillator element 2 whose fluorescence decay constant is lower than that of the first hybrid plastic scintillator element 1, these plastic scintillator elements 1 and 2 forming a plastic scintillator assembly.The first hybrid plastic scintillator element 1 is preferably composed in whole or in part of a hybrid material whose fluorescence decay constant is within one of the aforementioned ranges for the hybrid material (for example, between 10 ns and 90 ns, or even between 15 ns and 80 ns, advantageously between 30 ns and 80 ns, particularly between 70 ns and 80 ns; or between 25 ns and 75 ns or even between 28 ns and 70 ns when the molar concentration of the main primary fluorophore consisting of naphthalene is between 95.6% and 99.1%). The device is preferably a phoswich type device, in which, for example, each plastic scintillator element is a plastic scintillator compartment.

[0161] However, this description is not limited to the incorporation of the hybrid material into a phoswich-type plastic scintillation detector. It is of interest whenever a person skilled in the art needs a plastic scintillator with a determined and optimized fluorescence decay constant.

[0162] The first hybrid plastic scintillator element 1 can be in direct contact with the second fast plastic scintillator element 2.

[0163] According to another alternative, the first hybrid plastic scintillator element 1 is in contact with the second fast plastic scintillator element 2 via a bonding layer 5. The plastic scintillator assembly therefore further comprises a bonding layer.

[0164] In the case where the plastic scintillator elements are parallelepiped in shape, the first hybrid plastic scintillator element and the second fast plastic scintillator element are typically in contact with each other via one of their faces, preferably their face with the largest surface area or the same surface area.

[0165] In the case where the plastic scintillator elements are cylindrical in shape, the first hybrid plastic scintillator element and the second fast plastic scintillator element are typically in contact with each other via their circular faces, which are generally of identical surface area at the point of contact.

[0166] Taking as a reference the direction of propagation of the ionizing radiation or the ionizing particle with respect to the device for detection by plastic scintillation, the first hybrid plastic scintillator element can be indifferently the upstream plastic scintillator element or the downstream plastic scintillator element, in which case the second fast plastic scintillator element is respectively the downstream or upstream plastic scintillator element.

[0167] With reference to the direction of propagation of the ionizing radiation or ionizing particle with respect to the device, the first hybrid plastic scintillator element 1 is preferably the upstream plastic scintillator element and the second fast plastic scintillator element 2 is the downstream plastic scintillator element.

[0168] Plastic scintillator elements 1 and 2 can have different thicknesses, so the device includes a thin plastic scintillator element and a thick, fast-acting scintillator element. Therefore, both configurations are possible: the first hybrid plastic scintillator element can be either the thin plastic scintillator element or the thick plastic scintillator element.

[0169] Preferably, the thickness of the first hybrid plastic scintillator element is less than that of the second fast plastic scintillator element. Thus, according to a preferred embodiment to promote beta / gamma discrimination, the device may comprise a first thin hybrid plastic scintillator element 1 and a second thick fast plastic scintillator element 2. Preferably, the device then comprises the first thin hybrid plastic scintillator element 1 upstream and the second thick fast plastic scintillator element 2 downstream, with respect to the R direction of propagation of the ionizing radiation or the ionizing particle relative to the device.

[0170] The thin plastic scintillator element can have a thickness of 10 µm to 1 mm, for example 50 µm to 1 mm, preferably 100 µm to 500 µm; and the thick plastic scintillator element can have a thickness from 1 mm to several centimeters, for example 1 mm to 10 cm, preferably 3 mm to 5 cm.

[0171] The second fast plastic scintillator element 2 can have a fluorescence decay constant between 1 ns and 7 ns.

[0172] The second fast plastic scintillator element 2 may comprise a polymer matrix that may be as defined in this description, in particular according to one or more of the variants described for this polymer matrix, and / or a fast primary fluorophore selected from 2,5-diphenyloxazole (PPO), the [ para ]-terphenyl (pTP), the [meta] -terphenyl (mTP), biphenyl, 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole (PBD), 2-(4'- t-butylphenyl)-5-(4"-biphenylyl)-1,3,4-oxadiazole (butyl-PBD), anthracene, or mixtures thereof. Preferably, the fast primary fluorophore is 2,5-diphenyloxazole (PPO), the [ para ]-terphenyl (pTP), or even the [meta]- terphenyl (mTP) or mixtures thereof.

[0173] The second fast plastic scintillator element 2 may include a secondary fluorophore which may be as defined in this description, in particular according to one or more of the variants described.

[0174] According to a second embodiment, the device for detection by plastic scintillation can comprise a single hybrid plastic scintillator element (a so-called "single-compartment" plastic scintillation device). Such a single-compartment device is advantageous when coupled to an electronic acquisition module with a sampling frequency below 250 MHz: according to the Niquist-Shannon theorem, a long pulse such as that obtained with a single hybrid plastic scintillator is better described with such an acquisition module for which the electronics are limited in the number of points per nanosecond.

[0175] In general, regardless of the embodiment, the part can be coupled to the electronic acquisition module by an optical interface layer 6, namely by optical coupling.

[0176] The optical interface layer has the particular property of allowing the radiation exiting the plastic scintillator element to pass through, especially in the downstream position. This layer may be composed in whole or in part of a material known to those skilled in the art, for example chosen from greases, adhesives, gels, cements, elastomeric compounds, silicone compounds or mixtures thereof.

[0177] The coupling between the part and the electronic acquisition module can be achieved directly or indirectly via the hybrid plastic scintillator element.

[0178] For example, this coupling is generally for the single hybrid plastic scintillator element.

[0179] The coupling with the hybrid plastic scintillator element is, however, indirect in the case of the phoswich scintillator: the downstream fast plastic scintillator element comes between these two parts, and it is the only one in direct contact with the electronic acquisition module.

[0180] Regarding the electronic acquisition module, it may include a photodetector 3, chosen for example from a photomultiplier, a photodiode, a CCD charge transfer camera or a CMOS sensor.

[0181] The electronic acquisition module can be placed downstream, with reference to the direction of propagation of the ionizing radiation or the ionizing particle with respect to the device, of the part as a hybrid plastic scintillator element, of the single hybrid plastic scintillator element, of the first hybrid plastic scintillator element 1 or of the second fast plastic scintillator element 2.

[0182] It can be calibrated in energy using standard scintillating materials.

[0183] Not being subject to the protection requested, a device for detection by plastic scintillation comprises a device as defined in this description according to one or more of its variants, consisting of a portable device for the detection of ionizing radiation, a detection portal or a CCD detector (English acronym for " Charge Coupled Device»).

[0184] Not being subject to the protection sought, a manufacturing process for a device for detection by plastic scintillation as defined in this description according to one or more of its variants, is such that the part as a hybrid plastic scintillator element is coupled (directly or indirectly) to the electronic acquisition module, in such a way that the module is able to collect the radioluminescent radiation emitted by the part when the latter is brought into contact with ionizing radiation or an ionizing particle.

[0185] The manufacturing process may be such that the device comprises a plastic scintillator assembly, the process comprising the following successive steps: a) to have a first hybrid plastic scintillator element 1 as a part and a second fast plastic scintillator element 2 whose fluorescence decay constant is lower than that of the first hybrid plastic scintillator element 1; each of these plastic scintillator elements having in addition a polished surface of the same dimension as that of the other plastic scintillator element; b) to couple, via their polished surface, the first hybrid plastic scintillator element 1 and the second fast plastic scintillator element 2 in order to obtain the plastic scintillator assembly; c) to couple the plastic scintillator assembly including the part to the electronic acquisition module, such that the module is able to collect the radioluminescent radiation emitted by the plastic scintillator assembly when the latter is brought into contact with ionizing radiation or an ionizing particle.

[0186] According to a first embodiment, the manufacturing process of the device is an autogenous coupling process by heat bonding: the step b") of coupling bonding can be carried out by heating the polished surface of the first hybrid plastic scintillator element 1 and the second fast plastic scintillator element 2 in order to soften these surfaces which are then pressed together in order to couple them.

[0187] According to a second embodiment, the manufacturing process for the device comprising a plastic scintillator assembly is a molecular autogenous coupling process (i.e., in situ autogenous), the process comprising the following successive steps: a) a plastic scintillator element, consisting of a first hybrid plastic scintillator element 1 as a part or of a second fast plastic scintillator element 2 whose fluorescence decay constant is lower than that of the first hybrid plastic scintillator element 1, is manufactured in situ by polymerization on the other plastic scintillator element which constitutes a polymerization support, in order to obtain a plastic scintillator assembly at the end of step a); b) the plastic scintillator assembly including the part is coupled to the electronic acquisition module, such that the module is able to collect the radioluminescent radiation emitted by the plastic scintillator assembly when the latter is brought into contact with ionizing radiation or an ionizing particle.

[0188] The coupling between the plastic scintillator elements 1 and 2 according to step b"), and / or the coupling according to which the electronic acquisition module is coupled with the plastic scintillator assembly according to step c") or step b‴) or with the single hybrid plastic scintillator element as defined in this description according to one or more of its variants, can be achieved by means of an optical interface layer 6.

[0189] The optical interface layer 6 can be an optical cement (e.g., type EJ-500), a so-called "coupling" solvent (usually an alcohol, such as isopropanol or 1-butanol) or preferably an optical grease (e.g., type RTV141A).

[0190] This interface layer typically has a thickness of 1 µm to 10 µm.

[0191] Not being subject to the protection requested, a plastic scintillation measurement method comprises the following successive steps: (i) a device for detection by plastic scintillation as defined in this description, in particular according to one or more of its variants, is brought into contact with ionizing radiation or an ionizing particle so that the part (by virtue of the hybrid material it contains) included in the device emits radioluminescent radiation; and (ii) the radioluminescent radiation is measured with the electronic acquisition module of the device.

[0192] Preferably, the measured radioluminescent radiation decay time is between 10 ns and 90 ns, even more preferably between 15 ns and 80 ns, even more preferably between 30 ns and 80 ns, particularly between 25 ns and 75 ns, more particularly between 28 ns and 70 ns.

[0193] Ionizing radiation or ionizing particles can originate from radioactive material emitting gamma rays, X-rays, beta particles, alpha particles, or neutrons. In such cases, the radioactive material may emit several types of ionizing radiation or ionizing particles. Advantageously, discrimination between gamma rays and beta particles based on the different pulse shapes can be performed during measurement step b) using the scintillation measurement method.

[0194] The radioluminescent radiation resulting from this exposure can be measured according to step ii) with a photodetector, such as for example a photodetector chosen from a photomultiplier, a photodiode, a charge-coupled device camera (CCD), a CMOS sensor (Complementary Metal-Oxide Semiconductor), or any other photon detector whose capture is converted into an electrical signal.

[0195] According to a preferred embodiment, the measurement method may include a step iii) in which the presence and / or quantity of radioactive material is determined from the measurement of radioluminescent radiation according to step ii), as is commonly practiced in plastic scintillation. As an example, the qualitative and / or quantitative measurement step iii) is described by analogy with plastic scintillation in the document "Techniques de l'ingénieur, Mesures de radioactivité par scintillation liquide, Référence p2552, published 10 / 03 / 2004". » [reference 10].

[0196] Quantitative determination can, in particular, measure the activity of the radioactive source. It can be carried out using a calibration curve.

[0197] This curve, for example, shows that the number of photons from the radioluminescent radiation emitted by a known radioactive material is correlated with the energy of the radiation incident on that radioactive material. From the solid angle, the distance between the radioactive source and the plastic scintillator, and the activity detected by the measurement method using the aforementioned plastic scintillator, it is then possible to quantify the activity of the radioactive source.

[0198] As previously stated, the invention relates to a polymerization composition for manufacturing a hybrid material (as defined in this description, according to one or more of its variants) for detection by plastic scintillation comprising: monomers, oligomers or mixtures thereof intended to form at least one polymer constituting a polymeric matrix as defined in this description according to one or more of the variants; a liquid fluorescent mixture comprising in molar concentration relative to the total number of moles of primary fluorophore in the liquid fluorescent mixture: i) 95.6% to 99.1 mol% of a principal primary fluorophore consisting of naphthalene; and ii) 0.9% to 4.4 mol% of an additional primary fluorophore having a centroid of the light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent between 0.2 and 1 (or even between 0.5 and 1).

[0199] The ready-to-use kits described below may be such that their molar concentration of the main primary fluorophore consisting of naphthalene and their molar concentration of the additional primary fluorophore are adapted to the concentrations of these primary fluorophores in the polymerization composition or extrusion mixture which they enable to be manufactured; knowing that these molar concentrations in the kits are generally preserved after such manufacture.

[0200] Monomers, oligomers or mixtures thereof may include at least one aromatic, (meth)acrylic or vinylic group.

[0201] The liquid fluorescent mixture may include a secondary fluorophore, as defined in this description, according to one or more of its variants.

[0202] Thus, according to some of these variants, the secondary fluorophore may have: a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 405 nm and 460 nm, and whose quantum yield of fluorescence in a nonpolar solvent is between 0.5 and 1, or; a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 460 nm and 550 nm, and whose quantum yield of fluorescence in a nonpolar solvent is between 0.5 and 1, or; a light absorption spectrum and a fluorescence emission spectrum whose centroid is respectively at a wavelength between 330 nm and 380 nm and between 550 nm and 630 nm, and whose quantum fluorescence yield in a nonpolar solvent is between 0.5 and 1.

[0203] The secondary fluorophore can be at a mass concentration relative to the mass of the polymerization composition which is between 0.002% and 0.5% by mass.

[0204] The polymerization composition may include 1 wt% to 25 wt% of the liquid fluorescent mixture.

[0205] It may also include a polymerization solvent.

[0206] The polymerization composition can be implemented in the manufacturing processes of the hybrid material or the part as described previously.

[0207] The invention also relates to a ready-to-use kit with mixed fluorophores for the manufacture of a polymerization composition (as defined in this description, according to one or more of its variants), comprising separately, for assembly, the following kit components: (i) monomers, oligomers or mixtures thereof intended to form at least one polymer constituting a polymeric matrix and; (ii) a fluorescent polymerization kit mixture comprising, in molar concentration relative to the total number of moles of primary fluorophore in the fluorescent polymerization kit mixture: (i) 95.6% to 99.1 mol% of a principal primary fluorophore consisting of naphthalene; and (ii) 0.9% to 4.4 mol% of an additional primary fluorophore having a centroid of the light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent between 0.2 and 1 (or even between 0.5 and 1).

[0208] Regarding the composition and proportion of its components, the fluorescent polymerization kit mixture is identical to the liquid fluorescent mixture described previously. However, when it does not contain a solvent, it differs from the liquid fluorescent mixture only in that it is in solid form rather than liquid.

[0209] The ready-to-use kit with mixed fluorophores may include: a first compartment I) containing the monomers, oligomers or their mixtures; a second compartment II) containing the fluorescent mixture for polymerization kit.

[0210] The fluorescent polymerization kit mix comprises i) 95.6% to 99.1 mol% of the main primary fluorophore consisting of naphthalene and ii) 0.9% to 4.4 mol% of the additional primary fluorophore.

[0211] The ready-to-use kit with mixed fluorophores may be such that a secondary fluorophore as defined in this description according to one or more of its variants, a polymerization solvent or their mixture is mixed with i) monomers, oligomers or their mixtures and / or ii) the fluorescent mixture for polymerization kit.

[0212] Typically, the secondary fluorophore can be mixed at the same molar concentration with i) monomers, oligomers or their mixtures and with ii) the fluorescent mixture for polymerization kit, to prevent any dilution phenomenon if necessary.

[0213] Typically, the polymerization solvent can be mixed with the monomers and oligomers.

[0214] The invention also relates to a ready-to-use kit with separate fluorophores, which may be suitable for the manufacture of a polymerization composition (as defined in this description, according to one or more of its variants, a composition which contains a molar percentage of a primary and secondary fluorophore of a more restricted range but covering the broader range of the ready-to-use kit with separate fluorophores), comprising separately, for assembly, the following kit components: (i) a first polymerization mixture comprising monomers, oligomers or mixtures thereof intended to form at least one polymer constituting a polymeric matrix as defined in this description according to one or more of its variants; and, in molar concentration relative to the total number of moles of primary fluorophore in the kit, 95.6% to 99.1 mol% of a principal primary fluorophore consisting of naphthalene; (ii) a second polymerization mixture comprising monomers, oligomers or mixtures thereof intended to form at least one polymer constituting a polymeric matrix as defined in this description according to one or more of its variants;and, in molar concentration relative to the total number of moles of primary fluorophore in the kit, 0.9% to 4.4 mol% of an additional primary fluorophore whose centroid of the light absorption spectrum and fluorescence emission spectrum have wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm respectively, the fluorescence decay constant is between 1 ns and 10 ns, and the fluorescence quantum yield in a nonpolar solvent is between 0.2 and 1 (or even between 0.5 and 1). Thus, according to a particular embodiment of the invention, the first polymerization mixture may comprise 96% (more precisely 96.0%) to 99.1 mol% of the main primary fluorophore consisting of naphthalene and the second polymerization mixture 4% (more precisely 4.0%) to 0.9 mol% of the additional primary fluorophore.

[0215] According to another particular embodiment of the invention, the first polymerization mixture may comprise 95.6% to 99.1 mol% of the main primary fluorophore consisting of naphthalene and the second polymerization mixture 0.9% to 4.4 mol% of the additional primary fluorophore.

[0216] The ready-to-use kit with separate fluorophores may include: a first compartment I') containing the first polymerization mixture; a second compartment II') containing the second polymerization mixture.

[0217] The first polymerization mixture and / or the second polymerization mixture may include a secondary fluorophore as defined in this description according to one or more of its variants, a polymerization solvent or a mixture thereof.

[0218] Regarding the ready-to-use kit with mixed fluorophores or the ready-to-use kit with separate fluorophores: monomers, oligomers or mixtures thereof may represent 75% to 99% by mass of the kit components, and / or; the main primary fluorophore may represent 1% to 25% by mass of the kit components, and / or; may further include at least one auxiliary compartment each containing III) a crosslinking agent or a polymerization initiator.

[0219] The ready-to-use kit with mixed fluorophores or the ready-to-use kit with separate fluorophores may be such that the additional primary fluorophore can represent 0.006% to 5% by mass of the kit components. Indeed, the concentration of the main primary fluorophore in the first polymerization mixture can be between 1% and 25% by mass relative to the monomers or oligomers, in order to avoid subsequent exudation into the polymer matrix as previously mentioned. The concentration of the additional primary fluorophore in the second polymerization mixture can also be 25% by mass relative to the monomers or oligomers, i.e., a maximum concentration of 25% × 20% = 5% in the case of a mixture with the maximum proportion of main primary fluorophore ([c]max = 25%) and the maximum proportion of additional primary fluorophore ([c]max = 20%).The same calculation for the minimum concentration is 1% × 0.6% = 0.006%.

[0220] The invention also relates to a ready-to-use kit with polymers for the manufacture of an extrusion mixture (as defined in this description, according to one or more of its variants), comprising separately, for assembly, the following kit components: (i) polymerized ingredients (optionally in granule form) intended to form a polymeric matrix as defined in this description according to one or more variants thereof; (ii) a fluorescent extrusion kit mixture comprising, in molar concentration relative to the total number of moles of primary fluorophore in the fluorescent extrusion kit mixture: (i) 95.6% to 99.1% of a primary primary fluorophore consisting of naphthalene; and (ii) 0.9% to 4.4 mol% of an additional primary fluorophore having a centroid of light absorption spectrum and fluorescence emission spectrum with wavelengths between 250 nm and 340 nm and between 330 nm and 380 nm, respectively, a fluorescence decay constant between 1 ns and 10 ns, and a fluorescence quantum yield in a nonpolar solvent between 0.2 and 1 (or between 0.5 and 1).

[0221] The polymerized ingredients have the same chemical composition as the polymer matrix. They differ essentially in that they are not in bulk form like the polymer matrix, but in dispersed form, for example in the form of granules.

[0222] The ready-to-use polymer kit may include: a first compartment I") containing the polymerized ingredients; a second compartment II") containing the liquid fluorescent mixture for extrusion kit.

[0223] The ready-to-use kit with polymers may be such that a secondary fluorophore as defined in this description according to one or more of its variants, a polymerizing solvent or their mixture is mixed with i) the polymerized ingredients and / or ii) the fluorescent mixture for extrusion kit.

[0224] The ready-to-use kit with polymers may also include: a secondary compartment containing the secondary fluorophore and / or a polymerization solvent.

[0225] Each kit may include instructions giving the nomogram of the mixture to be made between the main primary fluorophore and the additional primary fluorophore to obtain the desired fluorescence decay constant.

[0226] The components of each kit can be assembled for the subsequent manufacture of the polymerization composition of the invention, in particular for simultaneous, separate or staggered use over time.

[0227] Other objects, features and advantages, including those of the aforementioned hybrid material not covered by the protection sought but which can be obtained with the polymerization composition and associated ready-to-use kits of the invention, will now be specified in the following description of particular embodiments, given by way of illustration and not limitation, with reference to Figures 1 to 8 attached. BRIEF DESCRIPTION OF THE FIGURES

[0228] There Figure 1 represents a table in which the fluorescence decay constant is measured for hybrid materials that differ in the ratio between the main primary fluorophore and the additional primary fluorophore and by the possible addition of a secondary fluorophore, as well as for comparison with a material not containing an additional primary fluorophore. Figure 2Arepresents the evolution of the median monoexponential fluorescence decay constant tau as a function of the molar proportion between the main primary fluorophore and the additional primary fluorophore according to the data of the Figure 1 It can represent a abacus included in instructions supplied with a ready-to-use kit. For comparison, the Figure 2B represents the evolution of the median monoexponential fluorescence decay constant tau as a function of the molar proportion between a main primary fluorophore different from that of the invention and an additional primary fluorophore. Figure 3 represents the pulse profile for different plastic scintillators, namely the evolution of their responses in counts per second as a function of time expressed in nanoseconds. A pulse recording profile is superimposed on these profiles. Figure 4represents the energy spectra of a plastic scintillator conforming to the description and a commercial slow plastic scintillator. Figures 5 and 6 represent a cross-sectional view of a "phoswich" type device for plastic scintillation detection as described previously, respectively without and with a bonding layer. Figure 7 represents a variant of the device of the Figure 6 . There Figure 8 represents the schematic view of a scintillating optical fiber equipped with a cladding. PRESENTATION OF SPECIFIC IMPLEMENTATION METHODS

[0229] Unless otherwise stated, examples are given at atmospheric pressure and ambient temperature. 1. Fabrication of a hybrid material for measurement by plastic scintillation. 1.1. Example 1 of manufacturing a plastic scintillator with secondary fluorophore.

[0230] A liquid mixture comprising fluorescent molecules (5 wt% (3.624 g) of naphthalene as the main primary fluorophore + 0.2 wt% (183 mg) of 2,5-diphenyloxazole (PPO) as an additional primary fluorophore and 0.02 wt% (15.2 mg) of 9,10-diphenylanthracene (DPA) as a secondary fluorophore) to which styrene (80 mL i.e. 94.78 wt%) is subsequently added is introduced into a single-necked flask previously dried under an inert argon atmosphere.

[0231] After five cold degassings under vacuum (known as the "freeze-pump-thaw" method), the polymerization medium obtained, once it has returned to room temperature, is poured into a mold suitable for giving the final shape to the plastic scintillator.

[0232] After five days of heating the sealed mold to 140 °C under an inert argon atmosphere, the plastic scintillator is demolded, ground and then polished. 1.2. Example 2 of manufacturing a plastic scintillator with secondary fluorophore.

[0233] A liquid mixture comprising fluorescent molecules (5 wt% naphthalene (3.624 g) + 0.2 wt% 2,5-diphenyloxazole (PPO, 183 mg) as primary fluorophores and 0.02 wt% 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene (dimethylPOPOP, 15.2 mg) as secondary fluorophore) to which styrene (80 mL, 94.78 wt%) is subsequently added is introduced into a single-necked flask previously dried under an inert argon atmosphere.

[0234] After five cold degassings under vacuum, the polymerization medium obtained, once it has returned to room temperature, is poured into a mold.

[0235] After five days of heating the sealed mold to 140 °C under an inert argon atmosphere, the plastic scintillator is demolded, ground and then polished. 1.3. Example 3 of manufacturing a plastic scintillator with crosslinked polymer matrix and secondary fluorophore.

[0236] A liquid mixture comprising fluorescent molecules (5 wt% naphthalene (3.624 g) + 0.2 wt% 2,5-diphenyloxazole (PPO, 183 mg) as primary fluorophores and 0.02 wt% 9,10-diphenylanthracene (DPA, 15.2 mg) as secondary fluorophore) to which are subsequently added 80 wt% styrene (64 mL) and then 14.78 wt% 1,4-butanediyl dimethacrylate (10.3 mL) as crosslinking agent is introduced into a single-necked flask previously dried under an inert argon atmosphere.

[0237] After five cold degassings under vacuum, the polymerization medium obtained, once it has returned to room temperature, is poured into a mold.

[0238] After ten days of heating the sealed mold to 65°C under an inert argon atmosphere, the plastic scintillator is demolded, ground and then polished. 2. Manufacturing of a range of plastic scintillators with variable proportions between primary fluorophores.

[0239] Plastic scintillators are manufactured according to the characteristics specified in the table of the Figure 1 using a manufacturing process similar to that disclosed in the previous examples.

[0240] They differ in the chemical composition of the polymer matrix (St = polystyrene; St / 1,4 = a mixture of styrene and 1,4-butanediyl dimethacrylate polymerized in a mass ratio of 5:1 between the two monomers, respectively) and in the molar ratio between the main primary fluorophore (naphthalene) and the additional primary fluorophore (2,5-diphenyloxazole = PPO). The mass concentration of each primary fluorophore is given as a percentage of the total mass of the plastic scintillator, the remainder being comprised of the mass percentage of the polymer matrix, the other primary fluorophore, and a constant concentration of 0.02% by mass of 9,10-diphenylanthracene (9,10-DPA) added as a secondary fluorophore not shown in the table. Figure 1 .

[0241] The fluorescence decay constant tau is measured by time-resolved single-photon counting as previously described. It is generally obtained here by biexponential fitting of the obtained values, with weighting factors for each exponential component indicated as percentages in parentheses. To facilitate comparison between different plastic scintillators, the biexponential tau is converted to the median monoexponential tau according to the equation below, where the goodness of fit of the measurement relative to the light pulse is evaluated by the chi-square value, which should ideally be as close to 1 as possible. Alternatively, commercial time-resolved single-photon counting instruments automatically calculate the median monoexponential or even biexponential rate from the recorded data.

[0242] The monoexponential tau constant of median fluorescence decay can be calculated from the following formula: τ m é dian = τ rapide × % rapide + τ lent × % lent

[0243] The percentages "% fast" and "% slow" represent the respective weights of the fast and slow decay. They are adjusted to best describe the median decay. Their sum equals 100%.

[0244] Thus, the Figure 2AThis graph represents the evolution of the median monoexponential fluorescence decay constant (tau) as a function of the naphthalene / PPO molar ratio. It clearly shows the continuous evolution of the fluorescence decay constant as a function of the molar ratio between the primary primary fluorophore and the additional primary fluorophore. This evolution takes the form of a decreasing exponential curve, which is indicative of synergy between the primary and additional primary fluorophores. In the absence of such synergy, the evolution of the time constant as a function of the molar ratio would be a linear curve directly connecting the values ​​at 100% and 0%, reflecting the simple gradual replacement of one primary fluorophore by another.

[0245] For comparison, the main primary fluorophore according to the Figure 2AThe naphthalene / PPO combination contained in the aforementioned hybrid material has been replaced by pyrene, a compound which belongs to the family of condensed aromatic compounds just like naphthalene, as shown in the molecular structures below:

[0246] The evolution of the median monoexponential fluorescence decay constant (median monoexponential tau) is studied as a function of the pyrene / PPO molar ratio in a manner similar to the study of the Figure 2A The result is illustrated by the Figure 2B which shows that this evolution does not at all have the form of a decreasing exponential: there is therefore no synergistic effect between pyrene and PPO, unlike the combination of the main primary fluorophore and the additional primary fluorophore included in the aforementioned hybrid material.

[0247] Another advantage of using a hybrid material for plastic scintillation measurement is demonstrated by the Figure 3 which illustrates the type of response pulse obtained for a plastic scintillator referenced by an index in the figure: fast (index a): reference scintillator “Eljen EJ-200” marketed by Eljen Technology; slow (index b): reference scintillator “Eljen EJ-240” marketed by Eljen Technology; hybrid (index c): comprising the aforementioned hybrid material.

[0248] The recording profile used (500 ns with a noise of 10 hits / second) is superimposed on the pulses of these three plastic scintillators.

[0249] There Figure 3demonstrates the advantages of a plastic phoswich scintillator comprising a fast compartment and a hybrid compartment as described above compared to a plastic phoswich scintillator comprising a fast compartment and a slow compartment: for electronic noise for example estimated at 10 counts per second, the hybrid pulse of the hybrid compartment has a better signal-to-noise ratio than the slow pulse of the slow compartment, thanks to the greater amplitude of the hybrid pulse.

[0250] Data acquisition is achieved by opening a time gate to record these pulses. As previously mentioned, the duration of this recording is generally chosen to be 6 to 10 times greater than the highest fluorescence decay constant, this decay constant corresponding, for each pulse, to the pulse's x-axis width expressed in nanoseconds. In the case of high count rates, such as when a high-activity radioactive source is placed in the presence of the phoswich device, the use of a slow compartment therefore implies using a much longer recording window: several pulses can then coexist in the same time window (stacking phenomenon), which results in acquisition errors if these pulses cannot be distinguished.

[0251] These properties of a hybrid compartment are therefore particularly advantageous for beta particle discrimination in a gamma radiation environment with a "phoswich" device comprising a hybrid compartment (especially when it is the thinnest compartment) and a fast compartment, each of these two compartments detecting the beta particle and gamma radiation respectively. 3. Example of qualitative or quantitative measurement of a radioactive material in plastic scintillation according to the aforementioned measurement method. 3.1. Measurement protocol.

[0252] A plastic scintillator comprising the aforementioned hybrid material in which a secondary fluorophore is incorporated is connected by means of optical grease to a photomultiplier tube which fulfills the function of photodetector of an electronic acquisition module.

[0253] Following its exposure to radioactive material, the plastic scintillator emits scintillation photons which are converted into an electrical signal by the high-voltage powered photomultiplier tube.

[0254] The electrical signal is then acquired and analyzed using an oscilloscope, spectrometry software, or an electronic data acquisition card. The data collected is then processed by computer.

[0255] This analysis results in an energy spectrum histogram representing the channels (derived from an output energy) on the x-axis and the number of counts per second on the y-axis. After calibration with a gamma-emitting source of known energy, the energy of the radioactive material to be measured is determined. 3.2. Quantitative measurement with the scintillator.

[0256] Based on this measurement protocol, a quantitative measurement is performed with a beta radioactive source of chlorine-36 with an activity on 4π equal to 6 kBq. This source is placed on the upper part of the plastic scintillator.

[0257] A cylindrical plastic scintillator with a circular cross-section, a diameter of 49 mm and a height of 35 mm (reference F30B in the table of the Figure 1 The device is coupled with Rhodorsil RTV141A optical grease to the photocathode of a photomultiplier tube (Hammamatsu H1949-51 model) powered by a high voltage (Ortec 556 model). The signal output from the photomultiplier tube is then captured and digitized by an electronic board designed by the inventor. This board can be replaced by another equivalent electronic board (e.g., CAEN DT5730B model) or an oscilloscope (e.g., Lecroy Waverunner 640Zi model).

[0258] Initially, the system (scintillator + photomultiplier) undergoes energy calibration using two radioactive sources: one emitting gamma rays in the [0-200 keV] range and the other in the [500-1.3 MeV] range. This energy calibration is performed by identifying the channel corresponding to 80% of the Compton front amplitude. For example, if the Compton front's ordinate corresponds to 100 counts per second, the abscissa on the Compton front's descent at 80 counts per second associates the Compton front energy (in keV) with the channel.

[0259] In a second step, once this calibration was completed, the chlorine-36 beta source was attached to the top surface of the plastic scintillator. Analysis of the energy spectrum yielded a read activity of 2.1 kBq (and therefore an intrinsic efficiency indicating that 70% of the incident radiation is measured) and a photoelectric peak centered around 250 keV.

[0260] The energy spectrum of the obtained hybrid plastic scintillator is shown on the Figure 4 (index (c')). For comparison, it is superimposed on that of a slow plastic scintillator ("Eljen EJ-240 slow" marketed by Eljen Technology - index (b') on the Figure 4 ) whose measured intrinsic efficiency is 54%. 4. Geometries of the aforementioned device for detection by plastic scintillation.

[0261] Such a device is described with reference to Figures 5 and 6 These figures represent, along a longitudinal axis with reference to the R radiation, cross-sections of a parallelepiped-shaped plastic scintillator of the "phoswich" type. Thus, unless otherwise indicated, each part of the device shown here is parallelepiped-shaped. The same numerical references designate the same elements in both figures. 4.1. Device with a bonding layer.

[0262] According to a first embodiment illustrated by the Figure 5The plastic scintillation detection device D comprises a component that is a first hybrid plastic scintillator element 1 made entirely or partially of the aforementioned hybrid material, and a second fast plastic scintillator element 2. These elements are respectively located upstream and downstream with respect to the direction R of propagation of the incident radiation (or the incident particle) on the phoswich scintillator. By convention, they are therefore referred to in the following description as "upstream hybrid scintillator 1" and "downstream fast scintillator 2". In the configuration illustrated by the Figure 5 The upstream hybrid scintillator 1 is described as "thin" because it has a smaller longitudinal thickness than the downstream fast scintillator 2, described as "thick." The plastic scintillation detection device, exhibiting all these characteristics, demonstrates improved discrimination between gamma rays and beta particles.

[0263] The upstream hybrid scintillator 1 and the downstream fast scintillator 2 are optionally contained within an envelope 8 which may constitute the housing or frame of the device. They are fixed to each other with an optical interface layer forming a bonding layer 5.

[0264] The bonding layer 5 is generally a separate layer from the upstream hybrid scintillator 1 and the downstream fast scintillator 2, for example, an add-on layer. However, it can be a layer composed of an intermediate material resulting from the fusion of the material of the upstream hybrid scintillator 1 and the downstream fast scintillator 2, as in plastic scintillation detectors comprising two scintillators bonded together by thermomechanical pressing.

[0265] The bonding layer 5 can be an optical layer that is transparent to luminescent radiation. It can be composed of a bonding material chosen from among greases, adhesives, gels, optical cements, elastomeric compounds, and silicone compounds commonly used in optics. Such a material allows the light radiation exiting the downstream scintillator to pass through.

[0266] A photodetector 3 (such as, for example, a photomultiplier) is fixed on the downstream fast scintillator 2 with an optical interface layer 6. It is suitable for collecting the radioluminescent radiation resulting from the contact of an ionizing particle or ionizing radiation with scintillators 1 and 2.

[0267] The face of the upstream hybrid scintillator 1 that first receives the incident radiation along the propagation direction R to be detected is covered with a thin metallic layer 4. This metallic layer 4 forms an entrance window with which the incident radiation (or the incident particle) comes into contact, while simultaneously preventing ambient light from also contacting the upstream scintillator by isolating it from the light. The lateral faces of the upstream and downstream scintillators are covered with a reflector or light diffuser 7 made of a reflective material, such as aluminum (aluminized Mylar, aluminum foil, etc.), or of a diffusing material, such as Teflon, titanium dioxide (TiO₂) paint, magnesium oxide (MgO) paint, or Millipore filter paper. 4.2. Device without a bonding layer.

[0268] According to a second embodiment illustrated by the Figure 6The plastic scintillation detection device D has a structure as described in document WO 2013076279 [reference 11]. It therefore does not include a bonding layer such as the optical interface layer 5 described in the Figure 5 The device for detection by plastic scintillation without a bonding layer differs, however, from that described in reference [8] in that it includes a first hybrid plastic scintillator element made up entirely or partly of the aforementioned hybrid material.

[0269] The D-type plastic scintillation detection device without a bonding layer, illustrated by the Figure 6comprises a first hybrid plastic scintillator element 1 made entirely or partially of the aforementioned hybrid material, and a second fast plastic scintillator element 2. These elements are respectively located upstream and downstream with respect to the direction R of propagation of the incident radiation (or incident particle) on the phoswich scintillator. In the configuration illustrated by the Figure 5 The upstream hybrid scintillator 1 is described as "thin" because it has a smaller longitudinal thickness than the downstream fast scintillator 2, described as "thick." The plastic scintillation detection device, exhibiting all these characteristics, demonstrates improved discrimination between gamma rays and beta particles.

[0270] The upstream hybrid scintillator 1 and the downstream fast scintillator 2 are in direct contact and fixed to each other by an autogenous coupling process. In this coupling process, a first cross-linked plastic scintillator is prepared and then polymerized. After this first solid formulation, the monomer solution containing the fluorescent mixture to make the second scintillator is poured onto the first scintillator, and the assembly is then heated.

[0271] Scintillators 1 and 2 are optionally contained in an envelope 8 which may constitute the housing or the frame of the device.

[0272] A photodetector 3 (such as, for example, a photomultiplier) is fixed on the downstream fast scintillator 2 with an optical interface layer 6. It is suitable for collecting the radioluminescent radiation resulting from the contact of an ionizing particle or ionizing radiation with scintillators 1 and 2.

[0273] The face of the upstream hybrid scintillator 1 which first receives the incident radiation (or the incident particle) according to the direction of propagation R to be detected is covered with a layer opaque to light 9. This opaque layer 9 constitutes an entrance window with which the incident radiation comes into contact, while limiting the contact of ambient light with the upstream scintillator.

[0274] The lateral faces of the upstream and downstream scintillators are covered with a light reflector or diffuser 7. The light-opaque layer 9 is permeable to the passage of beta and gamma radiation. It is composed of an opaque material such as Mylar.

[0275] As previously mentioned, the upstream hybrid scintillator 1 can have a thinner profile than the downstream fast scintillator 2. Such a configuration is shown on the Figure 7 . 4.3. Sparkling optical fiber.

[0276] There Figure 8represents a scintillating optical fiber 10 with a cylindrical cross-section. It comprises a polymer fiber 11 composed in whole or in part of the aforementioned hybrid material. The polymer fiber 11, constituting the inner core of the fiber, is covered by a cladding 12 covering the polymer fiber and composed in whole or in part of a sheathing material.

[0277] The invention is applicable to fields where scintillators are used, in particular: In the industrial sector, for example, for measuring the physical parameters of parts during manufacturing, for non-destructive testing of materials, for monitoring radioactivity at site entry and exit points, and for monitoring radioactive waste. In the geophysical sector, for example, for assessing the natural radioactivity of soils. In the field of fundamental physics, and in particular, nuclear physics. In the field of property and personnel security, for example, for the security of critical infrastructure, the screening of goods in transit (luggage, containers, vehicles, etc.), and for radiation protection of workers in the industrial, nuclear, and medical sectors. In the field of medical imaging. REFERENCES CITED

[0278] [1] Moser, S. W.; Harder, W. F.; Hurlbut, C. R.; Kusner, M. R. "Principles and practice of plastic scintillator design", Radiat. Phys. Chem., 1993, Vol. 41, No. l / 2, 31-36. [2] Bertrand, G. H. V.; Hamel, M.; Sguerra, F. "Current status on plastic scintillators modifications", Chem. Eur. J., 2014, 20, 15660-15685. [3] Wilkinson, D. H. "The Phoswich - A Multiple Phosphor", Rev. Sci. Instrum. 1952, 23, 414-417. [4] M. Wahl, "Time-Correlated Single Photon Counting", note technique de la société PicoQuant, 2014. [5] D. V. O'Connor, D. Phillips, Time Correlated Single Photon Counting, Academic Press, New York, 1984, pages 25 à 34. [6] Rohwer, L. S., Martin, J. E.; "Measuring the absolute quantum efficiency of luminescent materials", J. Lumin. 2005, 115, pages 77-90. [7] Velapoli, R. A.; Mielenz, K. D. "A Fluorescence Standard Référence Material: Quinine Sulfate Dihydrate", Appl. Opt., 1981, 20, 1718. [8] WO 2013076281.[9] Techniques de l'ingénieur, Extrusion - single-screw extrusion (part 1), Reference AM3650, 2002 publication.

[10] Techniques de l'ingénieur, Radioactivity measurements by liquid scintillation, Reference p2552, 10 / 03 / 2004 publication.

[11] WO 2013076279.

Claims

1. Polymerization composition for manufacturing a hybrid material for plastic scintillation detection comprising: - monomers, oligomers or their mixtures intended to form at least one constituent polymer of a polymeric matrix; - a liquid fluorescent mixture comprising, in a molar concentration with respect to the total number of moles of primary fluorophore in the liquid fluorescent mixture; i) from 95.6 molar% to 99.1 molar% of a main primary fluorophore consisting of naphthalene; and ii) from 0.9 molar% to 4.4 molar% of an additional primary fluorophore, the centroid of the light absorption spectrum and of the fluorescence emission spectrum of which respectively have a wavelength comprised between 250 nm and 340 nm and comprised between 330 nm and 380 nm, the fluorescence decay constant of which is comprised between 1 ns and 10 ns and the fluorescence quantum yield in a nonpolar solvent of which is comprised between 0.2 and 1.

2. Polymerization composition according to claim 1, wherein the liquid fluorescent mixture comprises from 96 molar% to 99.1 molar% of the main primary fluorophore.

3. Polymerization composition according to claim 1 or 2, wherein the liquid fluorescent mixture comprises a secondary fluorophore.

4. Polymerization composition according to claim 3, wherein the secondary fluorophore is at a concentration by weight, with respect to the weight of the polymerization composition, which is comprised between 0.002% and 0.5% by weight.

5. Polymerization composition according to any one of the preceding claims, further comprising a polymerization solvent.

6. Ready-for-use kit with mixed fluorophores for the manufacture of a polymerization composition as defined according to any one of claims 1 to 5 comprising, separately for the purpose of the assembling thereof, the following components of the kit: i) monomers, oligomers or their mixtures intended to form at least one constituent polymer of a polymeric matrix, as defined in claim 1; ii) a fluorescent mixture for a polymerization kit comprising, as a molar concentration with respect to the total number of moles of primary fluorophore in the fluorescent mixture for a polymerization kit: i) from 95.6 molar% to 99.1 molar% of a main primary fluorophore consisting of naphthalene; and ii) from 0.9 molar% to 4.4 molar% of an additional primary fluorophore, the centroid of the light absorption spectrum and of the fluorescence emission spectrum of which respectively have a wavelength comprised between 250 nm and 340 nm and comprised between 330 nm and 380 nm, the fluorescence decay constant of which is comprised between 1 ns and 10 ns and the fluorescence quantum yield in a nonpolar solvent of which is comprised between 0.2 and 1.

7. Ready-for-use kit with mixed fluorophores according to claim 6, comprising - a first compartment I) containing the monomers, the oligomers or their mixtures; - a second compartment II) containing the fluorescent mixture for a polymerization kit.

8. Ready-for-use kit with mixed fluorophores according to claim 6 or 7, wherein a secondary fluorophore as defined according to claim 3 or 4, a polymerization solvent or their mixture is mixed with the i) monomers, oligomers or their mixtures and / or ii) the fluorescent mixture for a polymerization kit.

9. Ready-for-use kit with separate fluorophores for the manufacture of a polymerization composition for manufacturing an hybrid material for plastic scintillation detection, comprising: - monomers, oligomers or their mixtures intended to form at least one constituent polymer of a polymeric matrix; - a liquid fluorescent mixture comprising, in a molar concentration with respect to the total number of moles of primary fluorophore in the liquid fluorescent mixture; i) from 95.6 molar% to 99.1 molar% of a main primary fluorophore consisting of naphthalene; and ii) from 0.9 molar% to 4.4 molar% of an additional primary fluorophore, the centroid of the light absorption spectrum and of the fluorescence emission spectrum of which respectively have a wavelength comprised between 250 nm and 340 nm and comprised between 330 nm and 380 nm, the fluorescence decay constant of which is comprised between 1 ns and 10 ns and the fluorescence quantum yield in a nonpolar solvent of which is comprised between 0.2 and 1 ; the ready-for-use kit with separate fluorophores comprising, separately for the purpose of the assembling thereof, the following components of the kit: i') a first polymerization mixture comprising monomers, oligomers or their mixtures intended to form at least one constituent polymer of the polymeric matrix; and, in a molar concentration with respect to the total number of moles of primary fluorophore in the kit, from 95.6 molar% to 99.1 molar% of a main primary fluorophore consisting of naphthalene; ii') a second polymerization mixture comprising monomers, oligomers or their mixtures intended to form at least one constituent polymer of the polymeric matrix; and, at a molar concentration with respect to the total number of moles of primary fluorophore in the kit, from 0.9 molar% to 4.4 molar% of an additional primary fluorophore, the centroid of the light absorption spectrum and of the fluorescence emission spectrum of which respectively have a wavelength comprised between 250 nm and 340 nm and comprised between 330 nm and 380 nm, the fluorescence decay constant of which is comprised between 1 ns and 10 ns and the fluorescence quantum yield in a nonpolar solvent of which is comprised between 0.2 and 1.

10. Ready-for-use kit with separate fluorophores according to claim 9, comprising: - a first compartment I') containing the first polymerization mixture; - a second compartment II') containing the second polymerization mixture.

11. Ready-for-use kit with separate fluorophores according to claim 9 or 10, wherein the first polymerization mixture and / or the second polymerization mixture comprise a secondary fluorophore as defined in claim 3 or 4, a polymerization solvent or their mixture.

12. Ready-for-use kit with polymers for the manufacture of an extrusion mixture comprising, separately for the purpose of the assembling thereof, the following components of the kit: i") polymerized ingredients intended to form a polymeric matrix which comprises at least one constituent polymer formed from monomers, oligomers or their mixtures; ii') a fluorescent mixture for an extrusion kit comprising, at a molar concentration with respect to the total number of moles of primary fluorophore in the fluorescent mixture for an extrusion kit: i) from 95.6 molar% to 99.1 molar% of a main primary fluorophore consisting of naphthalene; and ii) from 0.9 molar% to 4.4 molar% of an additional primary fluorophore, the centroid of the light absorption spectrum and of the fluorescence emission spectrum of which respectively have a wavelength comprised between 250 nm and 340 nm and comprised between 330 nm and 380 nm, the fluorescence decay constant of which is comprised between 1 ns and 10 ns, and the fluorescence quantum yield in a nonpolar solvent of which is comprised between 0.2 and 1.

13. Ready-for-use kit with polymers according to claim 12, comprising: - a first compartment I") containing the polymerized ingredients; - a second compartment II") containing the liquid fluorescent mixture for an extrusion kit.

14. Ready-for-use kit with polymers according to claim 12 or 13, wherein a secondary fluorophore as defined according to claim 3 or 4, a polymerization solvent or their mixture is mixed with i) the polymerized ingredients and / or ii) the fluorescent mixture for an extrusion kit.

15. Ready-for-use kit with polymers according to any one of claims 12 to 14, further comprising: - a secondary compartment containing a secondary fluorophore as defined in claim 3 or 4 and / or a polymerization solvent.