Abstract: A PET and Compton imaging method implemented by a device including at least two facing PET modules. The device includes a Compton camera arranged outside a plane containing the PET modules for forming a trihedron with the PET modules and producing a Compton view. The acquisition fields of the PET and Compton views having an overlap area covering the object to be imaged. The device allowing the following steps to be carried out: acquisition of a Compton view; location of a dense area and its contour on the Compton view; Computation of the 2D map of the probability of detection of the presence of a source from the Compton view of the Compton camera; Coincidence detection by the PET cameras and association of a response line (LOR); and Segmentation of LORs crossing the dense area by using the detection probability determined by the Compton view.

Abstract: A system and method for imaging by gamma radiation detection having at least one processing unit analyzing at least one signal provided by at least one set of detection modules mounted on a frame and including, on the one hand, at least one module of Compton camera type having a field of view directed towards a volume delimited by the frame and, on the other hand, at least one pair of coincidence detection PET modules, diametrically opposite to each other on the frame and defining an imaging axis, the processing unit analyzing the signal derived from the Compton-type module to determine the intersection of the imaging axis with the field of view and to determine the optimal orientations and/or locations of the various detection modules on the frame so that the imaging axis passes through the source of the gamma radiation in the object to be imaged.

Abstract: A Compton camera system and method for detecting gamma radiation, comprising a gamma radiation source, at least one fast scintillator plate P1 of which the rise time to peak light is less than 1 ns, having a thickness greater than or equal to 5 mm, equipped with an array of segmented photodetectors (5) and a dedicated fast-reading microelectronic means. The system is characterised in that it is capable of measuring the spatial and temporal coordinates (X, Y, Z, T) and energy E at at least two successive positions of a gamma photon when said photon undergoes Compton scattering at a first point A before being absorbed at a second point B, by recognising circles of non-scattered photons corresponding to each scintillation interaction. The system has a module for estimating a valid Compton event. The detection system has two scintillator plates P1 and P2.

Abstract: The invention concerns a method for improving the energy resolution of a gamma ray detector comprising a monolithic scintillator and a photodetector segmented during a scintillation event characterized by the following steps:—detecting the time of arrival of the first photons on said photodetector;—counting, during a period T, which is between 2 and 6 times a transfer time (Te), the number and location of the first detected non-scattered photons;—determining the diameter and the position of a disk defined by a set of first non-scattered photons;—determining the position (X, Y) of a scintillation event from the location of said first detected non-scattered photons;—counting the number of the first detected non-scattered photons inside said disk during a period Td greater than a decay time (T) of the scintillator;—defining the energy of a gamma photon, said energy being proportional to the number of non-scattered photons counted inside the disc.

Abstract: The invention concerns a method for determining the depth of an interaction in a pixellated gamma radiation detector characterized in that it comprises the following steps: —detecting first photons on the detector (10); —measuring the arrival time (Tpc) of said first photons on the detector (10) for a central pixel; —measuring the arrival time (Tpa) of the first photons in a pixel adjacent to said central pixel; —comparing the time (Tpa) with the time (Tpc) in order to estimate the depth of interaction (Z) owing to the different light propagation speeds in adjacent pixels; —integrating the radiation emitted over the whole of the emission of a crystal of the detector in order to determine the energy of the interaction; and —recording the integral of the energy emitted by this detection. The invention further concerns a pixellated gamma radiation detector for implementing the above method.

Abstract: The invention relates to a system for detecting gamma radiation, such as a gamma camera, including a source of gamma rays, at least one plate P1 of a fast scintillator, the time thereof for rising to the light peak being less than 1 ns, said plate comprising a diffusing entry surface and a polished exit surface, having a thickness of no less than 10 mm, being provided with photodetectors and microelectronics for dedicated reading, characterized in that the microelectronics are of the ASIC type, in that the detector is segmented, and in that on said plate P1, each segment of said detector is capable of measuring a first trigger T1 such that a time resolution is lower than 100 ps; the detector can measure a space and time distribution of the first adjacent photons emitted by an event on the detectors for a time of more than 100 ps and no longer than the time for rising to the light peak of the scintillator.

Abstract: The invention relates to a process for manufacturing a single crystal comprising a rare-earth halide, having improved machining or cleavage behaviour, comprising heat treatment in a furnace, the atmosphere of which is brought, for at least 1 hour, to between 0.70 times Tm and 0.995 times Tm of a single crystal comprising a rare-earth halide, Tm representing the melting point of said single crystal, the temperature gradient at any point in the atmosphere of the furnace being less than 15 K/cm for said heat treatment. After carrying out the treatment according to the invention, the single crystals may be machined or cleaved without uncontrolled fracture. The single crystals may be used in a medical imaging device, especially a positron emission tomography system or a gamma camera or a CT scanner, for crude oil exploration, for detection and identification of fissile or radioactive materials, for nuclear and high-energy physics, for astrophysics or for industrial control.

Abstract: The invention relates to a process for manufacturing a single crystal comprising a rare-earth halide, having improved machining or cleavage behavior, comprising heat treatment in a furnace, the atmosphere of which is brought, for at least 1 hour, to between 0.70 times Tm and 0.995 times Tm of a single crystal comprising a rare-earth halide, Tm representing the melting point of said single crystal, the temperature gradient at any point in the atmosphere of the furnace being less than 15 K/cm for said heat treatment. After carrying out the treatment according to the invention, the single crystals may be machined or cleaved without uncontrolled fracture. The single crystals may be used in a medical imaging device, especially a positron emission tomography system or a gamma camera or a CT scanner, for crude oil exploration, for detection and identification of fissile or radioactive materials, for nuclear and high-energy physics, for astrophysics or for industrial control.

Abstract: The invention relates to a method of preparing a polycrystalline block of a halide of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3f, and f being greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln—X bond and, on the other hand, a sufficient amount of NH4X in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300° C., never going below 200° C. before the molten mass has been obtained.

Abstract: The invention relates to a method of preparing a polycrystalline block of a halide of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3f, and f being greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln—X bond and, on the other hand, a sufficient amount of NH4X in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300° C., never going below 200° C. before the molten mass has been obtained.

Abstract: The invention relates to a method of preparing a polycrystalline block of a halide of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3f, and f being greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln-X bond and, on the other hand, a sufficient amount of NH4X in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300° C., never going below 200° C. before the molten mass has been obtained.

Abstract: The invention relates to a method of preparing a polycrystalline block of a halide of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3f, and f being greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln—X bond and, on the other hand, a sufficient amount of NH4X in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300° C., never going below 200° C. before the molten mass has been obtained.

Abstract: Inorganic scintillator material of formula AnLnpX(3p+n) in which has a very low nuclear background noise and is particularly suitable as a detector scintillator for coating weight or thickness measurements, in the fields of nuclear medicine, physics, chemistry and oil exploration, and for the detection of dangerous or illicit materials.

Abstract: The invention relates to a process for manufacturing a single crystal comprising a rare-earth halide, having improved machining or cleavage behaviour, comprising heat treatment in a furnace, the atmosphere of which is brought, for at least 1 hour, to between 0.70 times Tm and 0.995 times Tm of a single crystal comprising a rare-earth halide, Tm representing the melting point of said single crystal, the temperature gradient at any point in the atmosphere of the furnace being less than 15 K/cm for said heat treatment. After carrying out the treatment according to the invention, the single crystals may be machined or cleaved without uncontrolled fracture. The single crystals may be used in a medical imaging device, especially a positron emission tomography system or a gamma camera or a CT scanner, for crude oil exploration, for detection and identification of fissile or radioactive materials, for nuclear and high-energy physics, for astrophysics or for industrial control.

Abstract: The invention relates to the handling of a composition comprising a rare-earth halide, especially within the context of the growth of crystals from said composition, said crystals generally being of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms chosen from Cl, Br or I, and A represents one or more alkaline metals such as K, Li, Na, Rb or Cs, e and f representing values such that e, which may be zero, is less than or equal to 2f and f is greater than or equal to 1. It is possible in this way to grow single crystals exhibiting remarkable scintillation properties.

Abstract: The invention relates to an inorganic scintillator material of formula AnLnpX(3p+n) in which Ln represents one or more rare earths, X represents one or more halogen atoms, chosen from F, Cl, Br or I, and A represents one or more alkali metals, such as K, Li, Na, Rb or Cs, n and p representing values such that n, which may be zero, is less than or equal to 2p, and that p is greater than or equal to 1, its content of daughter elements of uranium and thorium being low enough for the activity resulting from the alpha radiation from these elements to be less than 0.7 Bq/cc. This material has a very low nuclear background noise and is particularly suitable as a detector scintillator for coating weight or thickness measurements, in the fields of nuclear medicine, physics, chemistry and oil exploration, and for the detection of dangerous or illicit materials.

Abstract: The invention relates to a method of preparing a polycrystalline block of a halide of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms selected from the group consisting of Cl, Br and I, and A represents one or more alkali metals selected from the group consisting of K, Li, Na, Rb and Cs, e, which may be zero, being less than or equal to 3f, and f being greater than or equal to 1, having a low water and oxyhalide content, in which the method comprises heating a mixture of, on the one hand, at least one compound having at least one Ln—X bond and, on the other hand, a sufficient amount of NH4X in order to obtain the oxyhalide content, resulting in a molten mass comprising the rare-earth halide, the heating being followed by cooling, and the heating, after having reached 300° C., never going below 200° C. before the molten mass has been obtained.

Abstract: The invention relates to the handling of a composition comprising a rare-earth halide, especially within the context of the growth of crystals from said composition, said crystals generally being of formula AeLnfX(3f+e) in which Ln represents one or more rare earths, X represents one or more halogen atoms chosen from Cl, Br or I, and A represents one or more alkaline metals such as K, Li, Na, Rb or Cs, e and f representing values such that e, which may be zero, is less than or equal to 2f and f is greater than or equal to 1. It is possible in this way to grow single crystals exhibiting remarkable scintillation properties.

Abstract: The rare earth borides, e.g., the tetraborides and hexaborides of lanthanum, cerium and praseodymium, are directly prepared by heating/reacting a mixture of at least one rare earth chloride and elemental boron at an elevated temperature, e.g., a temperature ranging from 1,200.degree. to 1,500.degree. C.

Abstract: The rare earth borides are prepared at relatively low temperatures by reacting a rare earth halide with elemental boron in the presence of a reducing amount of aluminum metal.