An apparatus and method non-invasively interrogates an object to detect contraband. The apparatus irradiates the object with fast neutrons of energy greater than 6.7 MeV, and measures the ensuing gamma-ray spectra. Irradiation of the object is accomplished by producing a neutron beam and moving the interrogated object stepwise or continuously relative to the beam. The nuclear interactions of highly penetrating neutrons within the irradiated volume of the object give rise to energetic nuclear-species characteristic gamma-rays. The energy and intensity of the emitted gamma-rays provide information relative to the spatial and density distributions of the gamma-ray sources, i.e., the specific atomic nuclei within the object. From this information, three-dimensional images of the atomic nuclei spatial and density distributions are inferred. Such three-dimensional images allow a decision to be made as to the presence of contraband. Measurements are made using arrays of gamma-ray scintillator detectors. A decision analysis based on statistical methods (e.g., discriminant analysis) or an artificial neural system, or other expert system, facilitates a low false alarm rate. One embodiment of the apparatus includes neutron beam collimator means to define and limit the irradiation volume of the object, and auxiliary neutron shielding means to attenuate the neutrons in other than desired neutron beam direction(s). Another embodiment includes an X-ray system and combines electron density information obtained from an X-ray image of the object with the spatial and density distribution information of the gamma-ray sources in order to further enhance the decision analysis.

Apparatus and method for detecting contraband using fast neutron activation

A baggage system which employs a fan-shaped x-ray beam which scans baggage on a conveyor belt and produces images of the contents of the baggage on a video monitor. The output of an x-ray source is collimated into a narrow linear beam. Objects to be scanned are exposed to this beam with successive slices of the object being so exposed as the conveyor moves the object past the beam. A light emitting screen receives the beam after it has passed through the object and emits a light pattern in accordance with the characteristics of the object being scanned. The light output of the screen is received by an array of photodetectors which generate electrical signals in accordance with the intensity of the light received thereby. The outputs of the photo-detectors are sequentially sampled to provide a series of signals in accordance with the photo-detector outputs. These signals are converted to digital form and stored in a memory. The output of the memory is fed through appropriate video output circuits to a video monitor where an image of the object being scanned is displayed.

X-Ray line scan system for use in baggage inspection

A system for detecting and graphically displaying a contents of a fast-moving target object comprises: a radiation source, having a position such that at least a portion of radiation emitted from the radiation source passes through the fast-moving target object, the fast-moving target object having a variable velocity and acceleration while maintaining a substantially constant distance from the radiation source and being selected from the group consisting of: a vehicle, a cargo container and a railroad car; a velocity measuring device configured to measure the variable velocity of the fast-moving target object; a detector array comprising a plurality of photon detectors, having a position such that at least some of the at least a portion of the radiation passing through the target object is received thereby, the detector array having a variable count time according to the variable velocity and a grid unit size; a counter circuit coupled to the detector array for discretely counting a number of photons entering individual photon detectors, the counter circuit measuring a count rate according to a contents within the fast-moving target object; a high baud-rate interface coupled to the counter circuit for sending count information from the counter circuit at a rate fast enough to support real-time data transfer therethrough; and a processor coupled to the velocity measuring device and to the high-baud-rate interface, receiving count information from the high baud-rate interface and generating distortion-free image data in real time as a function of the count information and the variable velocity. A method for using the system is also disclosed.

Density detection using real time discrete photon counting for fast moving targets

A package inspection system is used for automatic inspection of a different content or identification of a content in a package such as a container especially a large container in unloading from a ship without opening or unpacking the container and comprises an X-ray transmitter, an X-ray receiver, and a processing unit for image processing.

Container inspection system

An x-ray scanner for detecting plastic articles has an x-ray source which generates a fan-shaped x-ray beam through which an article to be examined is moved. A primary radiation detector array is disposed at a side of the article opposite to the x-ray source and functions to provide a normal x-ray image identifying metal articles. Additional detectors, which detect scatter radiation are disposed around the examination space at a distance from the primary radiation detector. The scatter radiation detectors detect scattered radiation characteristic of that produced by plastic articles. Signals from the scatter radiation detectors are processed, by which the presence of a plastic article can be identified.

X-ray scanner for detecting plastic articles

The invention relates to a technique for monitoring objects such as parcels or luggage for the presence of a predetermined class of objects, such as guns and bullets, on the basis of contrast detection of transmitted high energy X-rays. An object to be analyzed is subjected to high energy x-ray in a range of 200-400KeV and a plurality of detectors are utilized to monitor the variation of transmission of various portions of the object. Signals developed by the detectors indicative of the x-ray transmission characteristics of the various portions of the object are applied to signal processing circuitry which is adjusted to generate an output signal if any of the detectors produce a signal of a value indicative of a gun or bullet. In the absence of a gun or bullet substantially all high energy x-ray is transmitted through the object and detected by the detectors thus resulting in relatively high signal output from the respective detectors. If, however, a gun or bullet is present within the object, a substantial portion of the high energy x-ray radiation will be absorbed by the gun or bullet thus resulting in a relatively low level signal output from the detectors monitoring that portion of the object within which the gun is located.

X-ray contrast detection system

Display storage tube

An electrode includes an electron or irradiation transmissive conducting layer and an electron-emissive layer of insulating material in spongy form. This layer may be of BaF2, LiF2, MgF2, MgO, Al2O2, CsI, KCl or NaCl and preferably has a density of only about 1% of the same material in bulk form, e.g. 0.01 to 0.1 gms. per cc. with a thickness of 10 to 100 m . The layer may be formed by deposition in a gaseous atmosphere, e.g. argon at 1 to 2 mm. of Hg pressure, with a spacing of about 3 inches between the evaporator and the receiver, which may be rotating. Alternatively magnesium may be burnt in air at atmospheric pressure about 14 inches from the receiver. The receiver may be an aluminium film supported by a metal ring and formed by vacuum deposition of aluminium on to a film of thermally removable cellulose nitrate to a thickness of 140 to 1000 . Specifications 792,507, 862,211 and 898,433 are referred to.

Transmissive spongy secondary emitter

Radiation sensitive device

A camera tube in which input radiation information is directed onto a radiation-sensitive target or the input radiation is converted to electrons directed onto an electron-sensitive target and the information is read out from the opposite side of the target by means of a high-energy electron beam.

Robert J Schneeberger

Papers

X-ray contrast detection system

Display storage tube

Transmissive spongy secondary emitter

Radiation sensitive device

A camera tube with porous switching layer