Method for reducing optical crosstalk in sipm radiation detectors
AssigneeCintilight, LLC
InventorsPhilipp Braeuninger-Weimer, Chad E. Seaver
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Abstract
Radiation detection systems and modules include scintillation crystals with silicon photomultiplier (SiPM) arrays on at least one face. The SiPM or SiPMs are operated in an overvoltage state to enhance detection sensitivity, which increases unwanted optical crosstalk. Various examples of spectrally selective crosstalk rejectors, such as layers, materials, films, and the like, are configured to transmissively pass higher wavelength scintillation photons while rejecting or absorbing lower-wavelength external crosstalk photons generated by neighboring SiPMs.
Claims45
A gamma radiation scintillator detector, comprising:
- a scintillation crystal to receive gamma radiation and produce scintillation photons;
- a first silicon photomultiplier (SiPM) optically coupled to a first face of the scintillation crystal to generate an electric signal in response to detected photons;
- and
- a spectrally selective crosstalk rejector positioned within an optical detection path of the first SiPM, the spectrally selective crosstalk rejector being substantially transparent to the scintillation photons and configured to absorb external crosstalk photons emitted by an avalanching single-photon avalanche diode (SPAD) that is external to the first SiPM.
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A gamma radiation detector module, comprising a plurality of scintillator detectors, where each scintillator detector comprises:
- a scintillation crystal to receive gamma radiation and produce scintillation photons;
- silicon photomultiplier (SiPM) arrays disposed on at least two different faces of the scintillation crystal;
- and
- a spectrally selective crosstalk rejection layer positioned between each SiPM and the scintillation crystal, wherein scintillation photons generated within the scintillation crystal are detected by a SiPM after a single pass through a crosstalk-rejection layer, wherein external crosstalk photons emitted by an avalanching single-photon avalanche diode (SPAD) of one of the SIPMs on a first face of the scintillation crystal and detected by another of the SiPMs on a second face of the scintillation crystal undergo at least two passes through crosstalk-rejection layers.
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A radiation detector module, comprising:
- a scintillation crystal with a refractive index, ns;
- and
- at least one silicon photomultiplier (SiPM) array having a pixel pitch, P, that is optically coupled to a face of the scintillation crystal via an interposed optical stack having a total thickness, d, wherein the optical stack includes a spectrally selective crosstalk rejection layer;
- wherein the thickness, d, of the interposed optical stack satisfies 2d*tan θs,max≤αP, where
- θ
- s
- ,
- max
- =
- arcsin
-
- (
- η
- i
- n
- s
- )
- ,
- where ηi is a smallest refractive index of a material in the interposed optical stack between the face of the scintillation crystal and the SiPM, and where 0<α≤0.5, such that interface-induced broadening is constrained to no more than a fraction α of the pixel pitch, P.
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Dependencies are inferred from the claim text.