# US 2010/0168947 A1 · Apparatus and method for detection, location, and identification of gamma sources > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0168947 A1 - Document ID: US20100168947A1 - Status: Published application - Kind: A1 - Application number: 11/808,648 - Filed: 2007-06-12 - Published: 2010-07-01 - Earliest claimed: 2006-06-13 - Assignees: Space Micro Inc. - Inventors: James H. Winso; Michael D. Fennell - Web page: https://patentgrep.com/patent/US20100168947A1 ## CPC - G01V 5/26: Passive interrogation, i.e. by measuring radiation emitted by objects or goods - G01T 1/20: with scintillation detectors - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00) ## Abstract An apparatus for detecting and determining a source azimuth for gamma radiation includes at least two scintillation crystals at angular offsets and directed toward a common plane of detection, photodetectors adjacent to each of the scintillation crystals for converting the light response of the scintillation crystals into distinct electrical signals, and a digital processing system configured to analyze spectral data from each electrical signal produced for each crystal. The digital processing system monitors a finite number of spectral windows corresponding to a selected set of radioisotopes, and uses one or more of the electrical signals to determine a signal intensity and a likely source azimuth for a detected radioisotope in the plane of detection. Another scintillation crystal directed outside of the common plane of detection may be used for three-dimensional detection. Related methods for detection and location of gamma ray sources are discussed. ## Claims ### Claim 1 An apparatus for detecting and determining a source azimuth for gamma radiation from a radiation source comprising a set of one or more radioisotopes, the apparatus comprising: a first scintillator detector ensemble comprising at least two scintillation detectors each a producing a distinct electrical signal and each comprising a scintillator crystal having a response varying with angular disposition with respect to a source, said crystals being disposed at angular offsets with respect to a reference axis and having an output and a processing and control circuit including a digital processing system configured to analyze spectral data from each electrical signal produced for each crystal, and a processing circuit to evaluate the electrical signals to determine a signal intensity and a likely source azimuth for at least one detected radioisotope in the plane of detection. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the processing circuit is further configured to monitor a finite number of spectral windows corresponding to said selected set of radioisotopes and compare detected energy spectra to stored signatures. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein each of the scintillation crystals has a length to diameter ratio equal to or greater than about 2:1. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein said scintillation crystal detectors are equiangularly spaced. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the scintillation crystals comprise cerium-doped lanthanum bromide. ### Claim 6 (depends on 1) The apparatus of claim 1, the apparatus further comprising: a transmitter for transmitting to a remote device a representation of said detected signal intensity and said likely source azimuth. ### Claim 7 (depends on 1) The apparatus of claim 1, the apparatus further comprising: a robotic vehicle and wherein processing and control system comprises a global positioning system interacting with said transmitter and said robotic vehicle. ### Claim 8 (depends on 1) The apparatus of claim 1, the apparatus further comprising: a second scintillator detector ensemble including at least one further scintillation detector at angular offset with respect to a second axis; wherein the digital processing system is further configured to use the further electrical signal and one or more of the electrical signals to determine a signal intensity and likely three-dimensional source azimuth for at least one detected radioisotope. ### Claim 9 (depends on 8) The apparatus of claim 8, the apparatus further comprising: global positioning system and compass sensors to enable tracking of the position and orientation of the apparatus; wherein the signal intensity and three-dimensional source azimuth are used with the global positioning system data and compass sensor data to calculate specific source coordinates and strength in a known environment. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein each scintillation crystal has a full width half magnitude energy resolution of less than 4% at 660 KeV. ### Claim 10 (depends on 8) The apparatus of claim 8, wherein the remote device is a hand-held remote readout, wherein the hand-held remote readout comprises GPS and compass sensors, wherein the hand-held remote readout indicates source position relative to the readout and calculated gamma field intensity at the remote readout location, and wherein the hand-held remote readout storing a time stamp to estimate the timing of radiation detection and cumulative exposure of the remote readout operator. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein each scintillation crystal detector comprises at least one end cap and at least one trim shield mounted parallel to the end cap. ### Claim 11 A method of detecting and determining a source azimuth for gamma radiation from a selected set of one or more radioisotopes, the method comprising: providing at least two scintillation detectors each comprising a scintillator crystal having a response varying with angular disposition with respect to a source, placing the at least two scintillation detectors at angular offsets to each other with respect to a common axis; producing at least one electrical signal for each scintillation detector in response to detected radiation; analyzing spectral data from each electrical signal produced for each crystal at a finite number of spectral windows corresponding to said selected set of radioisotopes; and calculating from one or more of the electrical signals a signal intensity and a likely source azimuth with respect to the reference axis for at least one detected. ### Claim 12 (depends on 11) The method of claim 11, the method further comprising: suppressing the calculation of the likely source azimuth for a given radioisotope unless an electrical signal within a spectral window corresponding to the given radioisotope exceeds a threshold. ### Claim 13 (depends on 11) The method of claim 11, wherein the calculating step comprises: determining a reference isotropic polar response from a combination of the electrical signals; and comparing each electrical signal to the reference isotropic polar response to determine the signal intensity and the likely source azimuth. ### Claim 14 (depends on 11) The method of claim 11, the method further comprising: cyclically monitoring each spectral window, wherein each cyclical iteration comprises first measuring the intensity of the spectral window having the highest intensity, and then adjusting the detection threshold in each subsequent lower spectral window by an amount associated with the intensity measured in higher windows. ### Claim 15 (depends on 11) The method of claim 11, the method further comprising: determining a normalization value based on the expected effect of scatter from high energy sources; and subtracting the normalization value from each signal intensity calculation. ### Claim 16 (depends on 11) The method of claim 11, wherein the calculating step comprises: comparing, for each photodetector, the electrical signal in a given spectral window to a stored history of signal measurements in the given spectral window to determine a signal intensity and a likely source azimuth. ### Claim 17 (depends on 11) The method of claim 11, the method further comprising: placing a further scintillation crystal detector at an angular offset to the other scintillation crystals; directing the further scintillation crystal outside of the common plane of detection; and producing a further electrical signal for the further scintillation crystal at a further corresponding photodetector adjacent to the further scintillation crystal; wherein the calculating step comprises calculating from the further electrical signal and one or more of the electrical signals a signal intensity and likely three-dimensional source azimuth for at least one detected radioisotope. ### Claim 18 (depends on 17) The method of claim 17, the method further comprising: converting the signal intensity and likely three-dimensional source azimuth into likely three-dimensional source position data; transmitting the three-dimensional source position data to a video system; and overlaying, at the video system, the three-dimensional source position data wherein the video system overlays the three-dimensional source on a video image of an environment in which the method is performed. ### Claim 19 (depends on 11) The method of claim 11, wherein the analyzing step includes: calibrating at least one of the scintillation crystals and corresponding photodetectors based on a temperature sensor reading from a temperature sensor monitoring the scintillation crystal. ### Claim 20 (depends on 11) The method of claim 11, the method further comprising: identifying the detected radioisotope by its spectral distribution.