A mask for use in compressed sensing of incoming radiation includes a material that modulates an intensity of incoming radiation, a plurality of mask aperture regions, and one or more axes of rotational symmetry with respect to the mask aperture regions. Each mask aperture region includes at least one mask aperture that allows a higher transmission of the incoming radiation relative to other portions of the mask aperture region. The relative transmission sufficient to allow a reconstruction of compressed sensing measurements and has a shape that provides a symmetry under rotation about the one or more axes of rotational symmetry. A mutual coherence of a sensing matrix generated by a rotation of the plurality of mask aperture regions is less than one. An imaging system for compressed sensing of incoming radiation including such a mask is also provided.

A system for directional detection of radiation, comprises a plurality of scintillating crystals, responsive to the radiation and being arranged three-dimensionally, with voids between adjacent crystals, such that there are crystals that are inner and crystals that are outer within the arrangement. The system also comprises a plurality of light sensors coupled to the crystals for receiving optical signals from the crystals and responsively generating electrical signals, and a data processor receiving an electrical signal separately from each light sensor and calculating a direction of the radiation based on relative intensities of the signals and mutual occultation among different crystals.

The present invention provides a rare-earth halide scintillating material and application thereof. The rare-earth halide scintillating material has a chemical formula of RE.sub.aCe.sub.bX.sub.3, wherein RE is a rare-earth element La, Gd, Lu or Y, X is one or two of halogens Cl, Br and I, 0≤a≤1.1, 0.01≤b≤1.1, and 1.0001≤a+b≤1.2. By taking a +2 valent rare-earth halide having the same composition as a dopant to replace a heterogeneous alkaline earth metal halide in the prior art for doping, the rare-earth halide scintillating material is relatively short of a halogen ion. The apparent valence state of a rare-earth ion is between +2 and +3. The rare-earth halide scintillating material belongs to non-stoichiometric compounds, but still retains a crystal structure of an original stoichiometric compound, and has more excellent energy resolution and energy response linearity than the stoichiometric compound.

The present invention relates to a rare earth halide scintillating material. The material has a general chemical formula La.sub.1-xCe.sub.xBr.sub.3+y, wherein 0.001x1, and 0.0001y0.1. The rare earth halide scintillating material involved in the present invention has excellent scintillation properties of high light output, high energy resolution, and fast decay.

A gamma-ray spectrum classification apparatus, comprising circuitry configured: to provide a denoising autoencoder to receive gamma-ray spectrum data representing a gamma-ray spectrum of a material to be classified and to determine feature data indicative of one or more features representative of the gamma-ray spectrum data; and to provide a classification neural network to receive the feature data and to classify the material to be classified as one of a plurality of predetermined classifications using the feature data.

A method for generating a response function of a scintillator to incident gamma rays of energy within a range of energies of interest, the method including: obtaining the responses {S.sub.i} of the scintillator to a plurality of known radionuclides i (i=1, . . . N), each radionuclide i emitting gamma rays with known energetic properties (E.sub.ij, Y.sub.ij), decomposing, for each radionuclide i, response S.sub.i into primary responses of the scintillator S.sub.ij=ƒ(λ.sub.ij, Y.sub.ij, X.sub.ij), each primary response corresponding to the response of the scintillator to a received gamma ray of a known energy E.sub.ij for this radionuclide i, deriving from the primary responses {S.sub.ij} the response function ƒ(λ, X) of the scintillator to an incident gamma ray of any energy E within the range of energies of interest.

Systems and methods to estimated mean randoms include acquisition of list mode data describing true coincidences and delay coincidences detected by a positron emission tomography scanner during a scan of an object, determination, for each crystal of the positron emission tomography scanner and for each of a plurality of time periods of the scan, of delay coincidences including the crystal based on the list mode data, determination, each crystal, of determine a singles rate associated with each time period based on the delay coincidences determined for the crystal over the time period, determination, for each time period, of determine estimated mean randoms for each of a plurality of pairs of the crystals based on the singles rate associated with the time period for each crystal of the crystal pair, and reconstruction of an image of the object based on the estimated mean randoms for each time period and the detected true coincidences.

A sensor for spectroscopic measurement of alpha and beta particles includes first and second layers, a photomultiplier, and an analyzer. A first material of the first layer scintillates a first stream of photons for each of the alpha particles. However, the beta particles pass through the first layer. A second material of the second layer scintillates a second stream of photons for each of the beta particles, but passes the first stream of photons for each alpha particle. The photomultiplier amplifies the first and second streams of photons for the alpha and beta particles into an electrical signal. The electrical signal includes a respective pulse for each of the alpha and beta particles. From the electrical signal, the analyzer determines a respective energy of each of the alpha and/or beta particles from a shape of the respective pulse for each of the alpha and beta particles.

A rare earth halide scintillation material the chemical formula of the material being CeBr.sub.3+x, wherein 0.0001x0.1. The rare earth halide scintillation material has excellent scintillation properties including high light output, high energy resolution, and fast decay.

A spectroscopic gamma and neutron detecting device includes a scintillation detector that detects gamma and thermal neutron radiation, the scintillation detector including signal detection and amplification electronics, and a stabilization module configured to measure a pulse height spectrum of neutron radiation, determine a thermal neutron peak position in the neutron pulse height spectrum originating from cosmic ray background radiation, monitor the thermal neutron peak position in the neutron pulse height spectrum during operation of the spectroscopic gamma and neutron detecting device, and adjust the signal detection and amplification electronics based on the thermal neutron peak position in the neutron pulse height spectrum, thereby stabilizing the spectroscopic gamma and neutron detecting device.