Shieldless Detector With One-Dimensional Directionality

Abstract

A system of particle detectors can determine the location of a source without rotations or iterations. Embodiments of the system may include a middle detector flanked by two side detector panels, without shields or collimators. The middle detector may be positioned toward the front and orthogonal to the side detectors. By comparing a ratio of the detector data to a predetermined angular correlation function, the system can determine both the sign and magnitude of the source angle in real-time. Embodiments of the system can rapidly and automatically localize sources including industrial, medical, and other benign sources as well as nuclear and radiological weapons materials, whether in vehicles or cargo containers, and can provide improved sensitivity in walk-through personnel portal applications, enable enhanced detection of hidden weapons by a mobile area scanner, and enable a hand-held survey meter that indicates the radiation level as well as the location of the source of radiation.

What is claimed is: 
     
         1 . A system for detection and localization of a radioactive source, comprising:
 two side detectors oriented parallel to a centrally positioned aiming plane, each side detector being configured to emit signals upon detecting particles from the source;   a middle detector positioned at least partially between the side detectors and configured to emit signals upon detecting particles from the source; and   a processor configured to calculate, based at least in part upon the signals, the angle of the source location relative to the aiming plane.   
     
     
         2 . The system of  claim 1 , wherein the side detectors are configured to block at least 40% of the particles orthogonally incident thereon. 
     
     
         3 . The system of  claim 1 , wherein the middle detector is positioned closer to the front of the system than the back of the system. 
     
     
         3 . The system of  claim 1 , wherein the system includes no passive shields or collimators. 
     
     
         4 . The system of  claim 1 , wherein the width of the middle detector is at least two times the thickness of the middle detector, and the middle detector is oriented perpendicular to the aiming plane. 
     
     
         5 . The system of  claim 1 , wherein the width of the middle detector is greater than the average interaction distance of the particles therein, and the thickness of the middle detector is less than the average interaction distance of the particles therein. 
     
     
         6 . The system of  claim 1 , further comprising a shield slug configured to block particles incident orthogonally thereon and positioned between the side detectors and behind the middle detector. 
     
     
         7 . The system of  claim 1 , wherein one of the side detectors is configured to emit a first signal, the other side detector is configured to emit a second signal different from the first signal, and the processor is configured to determine, based at least in part on the signals, which of the side detectors emitted each signal. 
     
     
         8 . The system of  claim 1 , further comprising a rear-facing detector positioned closer to the back than the front of the system and configured to emit signals upon detecting particles from the radioactive source. 
     
     
         9 . The system of  claim 1 , further comprising a fourth detector positioned between the side detectors and configured to measure the energies of the particles. 
     
     
         10 . The system of  claim 1 , further comprising a fourth detector positioned between the side detectors and configured to emit a first signal upon detecting an energetic electron, and a second signal different from the first signal upon detecting an energetic ion. 
     
     
         11 . The system of  claim 1 , further including a fourth detector positioned between the side detectors, wherein the side detectors are configured to detect particles in a first energy range, and the fourth detector is configured to detect particles in a second energy range different from the first energy range. 
     
     
         12 . The system of  claim 1 , further comprising an upper detector and a lower detector that abut a centrally positioned midplane that is orthogonal to the side detectors and orthogonal to the front of the system, wherein the upper detector and the lower detector are configured to emit respective signals upon detecting particles from the radioactive source, and wherein the processor is further configured to determine whether the source is above the midplane, below the midplane, or substantially on the midplane. 
     
     
         13 . The system of  claim 1 , wherein each side detector comprises an upper side portion and a lower side portion, wherein each respective upper side portion and lower side portion abut a centrally positioned midplane that is orthogonal to the side detectors and orthogonal to the front of the system, and wherein the processor is further configured to determine whether the source is above the midplane, below the midplane, or substantially on the midplane. 
     
     
         14 . The system of  claim 1 , further comprising a wearable monitor configured to determine when a person wearing the wearable monitor has experienced a health or safety emergency, and to responsively emit an alarm. 
     
     
         15 . A method for determining a direction toward a radioactive source comprising:
 providing a system comprising two side detectors positioned on opposite sides of an aiming plane respectively, and a middle detector positioned between the side detectors, each of the side and middle detectors being configured to detect particles from the radioactive source;   acquiring respective detection data from each of the side and middle detectors; and   determining, at least in part based on the detection data, the sign and magnitude of an angle between the aiming plane and the radioactive source.   
     
     
         16 . The method of  claim 15 , further comprising:
 obtaining a difference by subtracting detection data of one of the side detectors from detection data of the other side detector; and   obtaining a ratio by dividing the difference by detection data of the middle detector, or by dividing detection data of the middle detector by the difference.   
     
     
         17 . The method of  claim 16 , further comprising:
 comparing the ratio to a predetermined angular correlation function configured to indicate, according to the sign and magnitude of the ratio, the sign and magnitude of the angle between the aiming plane and the radioactive source.   
     
     
         18 . A system for locating a radioactive source, comprising:
 two side detectors configured to detect particles from the source respectively, and positioned on opposite sides of an aiming plane;   a middle detector configured to detect the particles and positioned between the side detectors; and   a processor configured to receive detection data from the side and middle detectors respectively, and to calculate the sign and magnitude of an angle indicating the source location.   
     
     
         19 . The system of  claim 18 , further including computer-readable media containing a predetermined angular correlation function that relates the angle to the detection data. 
     
     
         20 . The system of  claim 18 , wherein the processor is configured to determine the source location based on detection data acquired at a single orientation of the system.