JP2003517602A - Apparatus for high-speed detection of X-rays - Google Patents

Abstract

The present invention relates to the field of X-ray inspection systems, and more particularly, to the field of systems that use X-ray diffraction to analyze an object under inspection. X-ray diffraction has long been used as an aid in structural analysis, and information about the material being diffracted is typically derived by one of two methods: energy dispersion or angular dispersion. . Essential to conventional diffraction systems employing angular dispersion is the provision of a monochromatic incident X-ray beam. Conventionally, this is provided by filtering the desired spectral peaks from a polychromatic or quasi-monochromatic X-ray beam by balanced filtering techniques. This technique is ineffective in that it requires two diffraction images to be subtracted from each other to obtain the desired spectral peak. This results in beam attenuation and statistically inferior quality data. The present invention proposes the use of an array of semiconductor detector elements and associated electronics that can derive an essentially light-colored diffraction pattern from scattered polychromatic or quasi-monochromatic X-rays.

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to the field of X-ray inspection systems, and more particularly to the field of X-ray inspection systems that use X-ray diffraction to analyze an object under inspection.

BACKGROUND ART X-ray diffraction has long been used as an aid to structural analysis. The technique derives from the prominent attributes of crystals: they derive the diffraction of incident X-rays according to the Bragg equation: nλ = 2d sin θ 2θ is the axis passing through the X-ray source and the center of scattering in the crystal. Is the angle measured relative to which incident X-rays of wavelength λ are coherently dispersed; d is
Crystal lattice spacing (d spacing), and n is an integer. For example, Hardin
g and Kosanetzky J .; Opt. Soc. Am. A 4 (5) 933
As can be seen from -944,1987, information can also be derived from X-ray diffraction patterns extracted from amorphous or poorly ordered materials.

Crystal lattices have a large characteristic set of d-spacings. The range of d-spacings present in a material can be derived from the measurements taken while either λ or θ changes. The diffracted beam is formed when it hits the form of an X-ray detector,
The position of each spot (or peak) in the diffraction pattern is the value {d, λ, θ}
Results from the characteristic set of The spot intensity is the molecular content (mole) of the substance.
cular content). Information about diffractive materials is generally available in two ways: detecting the range of wavelengths diffracted through a certain scattering angle (energy dispersion), or looking at monochromatic X-rays dispersed through a range of angles. Any of that (angular dispersion) derives from the position and intensity of the peak in the diffraction pattern.

Essential to conventional diffractive systems that employ angular dispersion is the provision of a monochromatic incident x-ray beam. The terms monochromatic and polychromatic mean here a narrow δλ and a wide Δλ finite spectral range, δλ << Δλ, respectively. Narrow spectral range δλ
The midpoint λ ₀ is taken to be the wavelength of the monochromatic X-ray.

In conventional x-ray sources, polychromatic x-rays are produced by bombarding the anode material of interest, such as copper and tungsten with high energy electrons. The X-ray spectrum so produced comprises a continuous spectrum ("continuum") with added peaks at characteristic energies (to the anode material).
Continuum emission in conventional x-ray sources tends to dominate said emission. Monochromation is achieved by filtering the spectral region around the peak.

Quasi-monochromatic refers to any source that provides a narrow spectral output compared to conventional sources. In conventional sources, the continuum emission will dominate the line emission (peak), and in quasi-monochromatic sources the continuum will be the background and line emission will predominate. An example of a quasi-monochromatic source is a fluorescent X-ray source, where a high energy X-ray source is used to excite X-ray fluorescence in a material.

A quasi-monochromatic source produces a much narrower spectral range than a conventional polychromatic source, but it is not truly monochromatic and full monotonization is achieved by filtering outside the spectral region around the peak. Will

It is necessary to avoid contamination of the diffraction pattern by diffracted X-rays from other spectral regions in order to achieve a degree of monochromation suitable for applications where the X-ray scattering power of the material under examination is weak. Is. Thus, for some applications, a single filter is sufficient, while peak wavelength dominates in the diffraction pattern, but for more discriminating applications, balanced filter technology is used. Ask.

A balanced filter technique uses two high-pass filters with cut-off edges on either side of the desired spectral peak to filter two peaks in the same spectral region. It involves taking one diffraction image. One image is subtracted from the other, and the result is a filtered monochromatic diffraction pattern (occupying the spectral region between the absorption edges of the two filters). This technique has many disadvantages. In fact, it is inevitable that every filter will attenuate the beam to some extent within the spectral range of interest: this is compromised by the need to provide two filters. Providing a close match of the attenuation attributes of the filter is very difficult, which requires ensuring that a narrow energy band is sampled. With the result that the object under examination must be stationary or two detector systems are required during data capture to ensure that successive images are taken (one per filter). Two) Two images are required for the same scattering object. Subtracting two more images yields statistically inferior data.

Therefore, angular dispersive X-ray diffraction from weakly diffracting or otherwise noisy materials is used to provide an alternative technique for improving the extraction of structural information. The need has been noticed.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an angular dispersion X without the intensity loss inherent in conventional filter technology.
The purpose is to provide an apparatus suitable for structural inspection by line diffraction.

[0012]   Therefore, the present invention uses the angular range φ₀-Φ_dScattered by the substance of interest over
Providing a detection system for detecting quasi-monochromatic or polychromatic X-rays
The system has an angular range φ connected to each corresponding array of read channels. ₀ -Φ_dComprising an array of semiconducting detector elements, the detector comprising:
The device consists of a semiconducting material with band-gap transmission in response to irradiation by X-rays.
Manufactured such that each detector element has a size that depends on the incident X-ray energy.
To produce an electrical reaction, and each read channel has a semiconductor electrical response
To be converted into an electric pulse having a parameter representing the magnitude of the reaction.
Front end electronics; the pulse parameters are
Two preselected discriminator values and a digital output from the discriminating electronics
If it is between a counter arranged to count the number of signals
And a discrimination electronic device arranged so as to output.

The present invention provides the advantage that information about the substance of interest can be retrieved with a shorter question time of the substance of interest compared to the prior art. Scattering is detected over the spectrum of quasi-monochromatic or polychromatic x-rays, in all angles made by the detector array. Each parameter can be separated. The scattering angle is X
It can be determined from the position of the detector element at which the line beam is intercepted. A relatively simple electronic circuit is used in which the analog detector element response is converted to a digital output to provide a quick estimate of the X-ray energy-said output being an X-ray within a certain narrow energy range. It has one of two logical states to indicate the presence or absence of incidence only.

The detector system is particularly suitable for use in an X-ray diffraction system. In such systems, it is desirable to know both the energy (or wavelength equivalent) and angular deflection of the x-ray beam in order to estimate the grating spacing d that is characteristic of the material under examination. Detector arrays have been used in the prior art to determine scattering angles, but detector elements generally ensure that energy resolution is provided within a reasonable exposure timescale. Was unsuitable. This required the use of X-ray monochromation techniques prior to diffraction pattern detection. The monochromation process itself inevitably leads to a decrease in the intensity of the detected probe beam, which in turn leads to an increase in the target question time. In contrast, the present invention provides an inspection system capable of measuring both the scattering angle and energy of diffracted x-rays, and reduces the need for beam monochromation prior to detection. All X-rays scattered within the accepted angular range are detected by the semiconducting detector element. It is only after detection that the electronics provide a rapid means for recording an essentially monochromatic diffraction pattern, with no apparent discard of detection events within the desired energy band. In this way, two of the characteristic set values {d, ε (λ), θ} linked by the Bragg equation can be measured, and the characteristic d-interval is for extracting information about the target substance. Can be calculated as

The system may include at least two arrays of read channels, each semiconductor detector element being connected to a separate read channel, one from each array, and read channels in the same array , Having the discrimination electronics set to a value of the first and second discriminator which are substantially the same, they likewise
Different from the discriminator values suitable for read channels in other arrays.

This embodiment of the inspection system of the invention provides a means by which information can be retrieved simultaneously with the monochromatic diffraction pattern described above. The read channels of the different arrays are set to measure monochromatic diffraction patterns that occupy different parts of the quasi-monochromatic / polychromatic spectral range. In this way, more information can be extracted at the same interrogation time, further increasing the speed advantage this detection system has over the prior art.

The system is adapted to display, for each reading array, an X-ray scattering pattern derived from the position of each detector element in the array plotted against the number of counts registered in each connected reading channel. It may also include display means arranged in. This provides the effect of simplicity and the pattern is
It is displayed in a format commonly used for powder diffraction patterns. This facilitates rapid comparison with known diffraction patterns to aid in the identification of unknown materials.

The semiconducting element is preferably made from cadmium zinc telluride, gallium arsenide, lead iodide, or mercury iodide. These high atomic number semiconducting materials are
Presently, it meets the preferred criteria of detector element material for fabrication into commercially available arrays and for use in this aspect of the invention. These substances are
It can be used to provide a detector sensitive to the 60 KeV region of enhanced emission from a tungsten source. Such materials, due to their high extinction coefficient to Compton scattering ratio and high photoelectric absorption, cause the detector element to record virtually all incident photons. Moreover, they will be able to record the true energy of all relative incident X-ray photons,
It can be used to build detector elements with sufficient energy resolution (less than 10% full-width-half-maximum) in the 60 KeV energy range.

Preferably, the angular range φ _{0 to} φ _d is 2 to 8 degrees. This is 60 KeV
It corresponds to the angular range of interest in measuring the diffraction pattern from powdered material using the tungsten enhanced emission zone. Furthermore, the materials referenced in the previous paragraph provide sufficient spatial resolution for this angular range.

In an alternative feature, the present invention provides an x-ray source, a target material to be inspected, and a quasi-monochromatic or polychromatic x-ray beam produced by said source scattered from said target material to said detection system. There is provided an X-ray inspection system comprising a detection system arranged as described above, said detection system comprising the detection system described in detail in the preceding paragraph. This feature of the invention provides a system that allows for rapid data collection through the use of a detection system in which monochromation is effectively performed after diffracted x-rays within the angular range of interest are detected.

The quasi-monochromatic / polychromatic X-ray beam is preferably collimated into a fan beam to illuminate the coplanar two-dimensional array of voxels in the material of interest, and the system is illuminated. It includes focus collimating means arranged to pass only x-rays scattered from a single voxel at a certain depth and height in the array through the detection system.
The system may also include an array of focus collimating means and a separate array of detection systems, the collimating array members scattered from individual voxels at different heights within the illuminated voxel array. X-rays are stacked so that they pass through separate detection systems simultaneously. Further, the array of collimating means is preferably relative to the target material in the direction of the unscattered X-rays to allow detection of X-rays scattered from voxels at different heights within the target material. And can move.

These features are added to the implementation in a scanning x-ray inspection system that can be used to inspect the entire mass of a large number of objects in a realistic time of day. This reduces the total time taken to complete a complete inspection as compared to conventional inspection systems.
These embodiments, therefore, require high throughput in time that is within the traveller's tolerance, and are more likely to detect explosives, drugs, or other contraband scanning airport baggage. It is especially applicable to

The inspection system may include a plurality of detection systems that are symmetrically oriented to intercept a conical distribution of diffracted x-rays in symmetrically equivalent regions. This provides the effect of increased accuracy. Diffraction patterns detected by different detection systems can be averaged over the same monochromatic range to provide more accurate counting statistics and to improve the certainty that the substance of interest may be identified. it can.

BEST MODE FOR CARRYING OUT THE INVENTION For a more complete understanding of the present invention, an embodiment thereof will be described with reference to the accompanying drawings.

FIG. 1 illustrates an X-ray inspection system, generally designated 10. The system 10
A collimator arranged to pass X-rays 12 scattered from a volume element (voxel) 14 of the substance under examination towards an array of four linear detector arrays 16, 18, 20, 22. (Not shown). Each array, for example 16, includes a series of cadmium zinc telluride (CZT) detector device elements 16a, 16b, 16c ,. ． ． ． It is equipped with. Each detector device 16a,
16b, 16c ,. ． ． ． Is a separate read circuit, a separate array 24, 26 of read circuits for the two detector arrays 16, 20 shown in the drawing.
It is connected to the. Each array of read circuits 24, 26 is a detector array 16
, 18, 20, 22 and each of the detector elements 16a, 16b, 16c in the detector array 16, 18, 20, 22 for processing a signal received from the detector array.
,. ． ． Patterns 30 and 28 representing the intensity of X-ray irradiation 12 incident at the position
Is output.

FIG. 2a shows a single detection channel 40 of the X-ray system described in FIG.
Each such channel comprises one CZT detector element 16a connected to an associated read circuit 24a. The detection device 16a uses the incident X-ray photons 4
When 2a hits, an electrical reaction occurs. The magnitude of this reaction is proportional to the energy of the striking photon, and the reading circuit 24a.
This is what is processed by. The circuit 24a is a preamplifier.
A fier 44, a shaping amplifier 46, a low level discriminator 48, a high level discriminator 50 and a counter / buffer 52.

FIG. 2b shows an array 60 of detection channels 40 according to FIG. 2a. The array 60 comprises an array 24 of read circuits each connected to an array 16 of CZT detector elements.

FIG. 3 shows the principle of operation of the reading circuit in generating the pulse signal from the reaction of the detection device. The figure shows an array 1 of CZT detector elements 16a-h.
6 is shown. Each detector element 16a-h produces an electrical response to an incident X-ray photon 42a-h, the magnitude of which is proportional to the energy of the impinging photon. This reaction is amplified and shaped by the read array 24 of preamplifier 44 and shaping amplifier 46 to produce electrical pulses 72a-h. The discriminators 48, 50 in the read array 24 provide a digital output response (or count) when the magnitude of the electrical pulses 72a-h falls between a low level ε ₁ and a high level ε ₂ of the discriminator. 74a, c, e, g, h. Counter / buffer 52 is arranged to measure the number of counts in each channel 40 over a period of time.

Referring to FIG. 1, detection of an X-ray diffraction pattern according to the present invention is described. The target voxel 14 has a basic elemental volume (elemental) to be examined by X-ray diffraction.
volume). For the moment, voxels 14 and their associated diffraction patterns 12 are separated from adjacent voxels and their associated diffraction patterns,
That is, the voxels 14 include the entire object under examination, or some arrangement is used by which the separation can be effectively achieved. An arrangement of devices known to be able to effectively separate voxels in this way is described in PCT patent application, publication number WO 96/24863. However, the above 2
This feature is not central to the invention, even though the two systems can be combined very effectively. Therefore, a description of how the separation is achieved is given later. However, currently, X-rays diffracted from voxels 14 are not contaminated by adjacent voxel diffraction patterns.

A collimated beam of polychromatic X-rays (not shown) impinges on voxels 14. (Note: the skilled person will understand that quasi-monochromatic beams may also be used.) The voxel 14 diffracts X-rays according to the Bragg equation, a range of d's.
It has many crystals with spacing. In powdered material, the crystals are randomly oriented and each d-spacing is in many directions. Constant d
With respect to the spacing and the incident wavelength λ, the diffracted beam is therefore
mi-angle) Located along the surface of a cone of θ. Diffraction X with polychromatic incident beam
The line 12 forms a continuous series of cones in the range of half-vertical angle 0- [theta] _max . However, for each value of θ, there is a range of d and λ combinations that satisfy the Bragg equation, and x-rays of possible wavelengths that form the diffracted beam 12. The set 12 of diffracted beams can be foreseen to form the spatial overlap of many monochromatic (covering the wavelength region δλ) angular dispersion diffraction pattern.

The diffracted beam 12 comprises four linear arrays 16, 18, 20 of CZT detector elements.
, 22. Since the diffraction pattern 12 is conically symmetric, a single linear array is sufficient for its detection. However, four symmetrically oriented detector arrays 16, 18, 20, 22 provide better counting statistics when the detector results are averaged. One operation of such an array 16 is described, it being understood that the other three 18, 20, 22 operate in the same manner. The array 16, detector elements 16a which are arranged to extend relative angular range 0 to phi _d, 16b, 16c,. ． ． It is equipped with. The range φ _d is chosen to cover the higher intensity regions in the range of diffracted beams 0 to θ _max . For powdered compositions of interest at the airport, this range corresponds to a small angular dispersion. Each detector 16a, 16b, 16c ,. ． ． Therefore intercepts one angular region δθ of the diffraction pattern.

2a and 3, the function of the read channel 24 in providing energy discrimination (equivalent to resolving the added monochromatic diffraction pattern) is described. The CZT detector element 16a produces a charge pulse in response to irradiation of the X-ray 42a. The magnitude of this reaction is proportional to the energy of the X-rays incident on the element 16a during the reaction time interval. Preamplifier 44 and shaping amplifier 46 transfer the CZT detector response into an electrical pulse 72a having a height representative of the energy of incident x-ray 42a. If the height of this pulse falls between the low threshold ε ₁ set by the low level discriminator 48 and the high threshold ε ₂ set by the high level discriminator 50, it is registered as “hit”. Signal 74 a is transmitted to the counter 52. If the height of the peak pulse is outside the range δε = ε ₂ −ε ₁ set by the discriminators 48, 50, then hit is not registered. Counter 50 buffers the number of hits registered during the observation period, and these are
It is displayed as an intensity reading value at the position of the detector device element 16a in the diffraction pattern 28.

The diffraction pattern 28 displayed by the device 10 and described in FIG. 1,
30 is a monochromatic X-ray (energy within the range of ε ₁ −ε ₂ or equivalent wavelength)
A plot of the scattered intensity (number of counts) against the divergence angle (location of detector elements) of These patterns are equivalent to those detected with prior art angular dispersion diffractive systems, but without the inherent disadvantages of using filters in obtaining monochromaticity. All prior art devices that use filters to achieve monochromaticity, by their nature, result in a loss in intensity from the incident beam (due to the placement of the filter) or from the diffracted beam, followed by the There is a decline. In contrast, in this example, the present invention also discards potential information-carrying X-rays from outside the monochromatic range, but does not reduce the intensity of the X-rays in the detected monochromatic spectral region. .

A further advantage of the present invention over the prior art is achieved when a multi-channel read circuit is connected to each detector device element 16a, as described in FIG. In this figure, a single detector element 16a is shown connected to the first 24a, second 80a and third 82a read circuits. The multi-channel circuit comprises a common preamplifier 44 'as well as a shaping amplifier 46' and a plurality of discriminators 48,50 and a counter / buffer 52. Each read circuit 24a, 80a, 82a is identical to 24a described above, except that the discriminators 48, 50 in each are set to different threshold levels ε ₁ , ε ₂ . The first reading circuit 24a derives information related to the monochromatic range ε ₁ -ε ₂ while the second circuit 80a derives information from different monochromatic range ε ₃ -ε ₄ and the third 8th.
2a derives information from the third range ε ₅ −ε ₆ . Counts from the first 24a, second 80a, and third 82a read circuits are from read circuits set to the same individual thresholds from different detector elements to extract three diffraction patterns of the form 28. Combined with the counts, each plots the intensity against the scattering angle for different parts of the x-ray spectrum. Obviously this setting is not limited to only three reading circuits. A series of circuits may be provided that read information from a series of different monochromatic areas. In this way, information from other parts of the diffraction spectrum can be partially extracted from the detector element during a single, voxel irradiation period.

Due to the parallel processing capability of the read circuit, many monochromatic diffraction patterns can be extracted simultaneously from a typical polychromatic diffraction pattern. This reduces the information content to a large number of readily translatable conventional monochromatic displays, which can ultimately be used to improve the accuracy of the extracted structural details.

The present invention provides for situations where data collection needs to be completed as soon as possible.
Especially applicable. For example, baggage scanners at airports have a high throughput of traveler baggage and are reliable and reliable for detecting potentially small quantities of illegal substances such as drugs and explosives sealed in large containers. You need to have a system.
Similarly, the present invention can be used to quickly scan food, such as meat on conveyor belts, to detect bone, cartilage, or other inedible contaminants.

To facilitate this rapid scanning of large objects, it is necessary to be able to avoid interference between diffraction patterns generated from adjacent scatter centers. Each voxel must be able to work independently. As mentioned above, a method of achieving this is described in WO 96/24863, which explicitly cites its applicability to airport baggage scanning. The effect of linking the invention with it is readily apparent.

WO 96/24836 describes how irradiation of a large object by an incident fan beam, coupled with a particular form of collimation of the diffracted beam, results in scattering from the target voxel and that from adjacent materials. Explain how to enable enhanced discrimination between. The effect provided by the invention, namely a faster three-dimensional scanning of large objects, is further achieved by the application of the invention.

Consider a three-dimensional array of voxels illuminated by an x-ray fan beam.
Similar to 12, in the dimension of depth defined by the stacking in the direction of propagation of the incident X-ray beam, a conical diffraction pattern is produced from successive voxels. A focusing collimato that reflects the conical symmetry of the diffraction pattern.
r) can be used to focus on one particular depth.

FIG. 5 shows X-ray diffraction from the plane of a voxel element at one particular depth in a large three-dimensional object. This description is parallel to the voxel plane,
It is of a plane that is displaced in the direction of propagation of the incident X-ray beam. The diffracted beams from adjacent voxels have circular profiles 90a, 90b, 90c, ... Centered at the position of the voxel projected in this plane. ． ． Intersect this plane at. Incident X
The line fan beam is collimated to intersect only one line of voxels at each depth, defining a linear intersection 92 with the plane described in FIG. The focal collimator section 94 also intersects this plane. The section 94 comprises horizontal 94a and vertical 94b parallelizing sheets that provide vertical and depth specificity, respectively.

At any point in time, the interference resulting from scattering from adjacent horizontal voxels 90a, 90b, 90c, ie, perpendicular to the plane of the fan beam, is:
Only one "line" of the voxels 90e, 90a, 90d is
As illuminated by the effective X-ray line 92 formed by the beam,
It is easily avoided by collimating the beam. Voxels 90a, 9
0b, 90c can be moved relative to the fan beam so that the diffraction patterns from adjacent voxels are separated in time. Vertical, that is, fan
Only a section of each diffraction pattern of finite height is accepted by the focus collimator in order to avoid interference from voxels stacked in a direction in the plane of the beam direction. This is facilitated by the horizontal collimating sheet 94a.

The invention of WO 96/24863 is very effectively combined with the present invention to provide a high speed X-ray scanning device for the detection of explosives and / or drugs carried in airport baggage. Each elementary part of a piece of baggage behaves as a center of scattering (voxels) when illuminated with X-rays. The purpose of the airport scanning device is, firstly, to detect the presence of banned substances, and secondly, if something is detected, what it is and where in the baggage. To quickly scan the contents of baggage to detect if it is contained. Each basic diffraction pattern is
Analyzed for evidence of constant diffraction peaks, characteristic of expected banned substances. Identification can be achieved most quickly by comparison with a look-up table of diffraction patterns of known prohibited substances.

A focus collimator, as described in WO 96/24863, is described in FIG. 5 to provide simultaneous collimation of the diffraction pattern from all voxels at a particular depth, illuminated by the fan beam. Stacked vertically. One of the linear detector arrays 16 described in FIG. 1 and its associated array of read circuits 24 are used in this combined system, also stacked in the same direction. Each detector system (comprising detector array 16 and read circuit 24) is diffracted by each voxel element separated by a combination of fan beam irradiation 92 of WO 96/24863 and collimating system 94. One or many spectral series of patterns can be used for rapid detection.

To scan the entire baggage, the fan beam is arranged to illuminate one dimension (ie height). Baggage is generally a fan along its length.
It is moved by a conveyor belt in preparation for irradiation by the beam. The collimation 94 and detection 16,24 system is moved relative to the baggage to scan its depth. At each scan point, sufficient information must be gathered to identify the scattered voxel composition (as to whether it is contained in a prohibited material in the look-up table). This voxel point is identified by the structure of the conveyor belt / depth scanning system and which detection system registers the pattern. The ability to do this is known in the art. In order to allow the scan time of each voxel to be reduced to a value short enough that the overall baggage handling capacity of the airport can be scanned within an acceptable traveler delay. It is essential to have a detection device that can collect sufficient information quickly. This is accomplished in the present invention by the need for monochromatic filters and the use of energy sensitive detectors that prevent their inherent reduction in the X-ray intensity present in the diffraction pattern. The time required to collect data from each diffractive element is then reduced.

[Brief description of drawings]

[Figure 1]   FIG. 1 diagrammatically shows an embodiment of the X-ray inspection system according to the invention.

Figure 2a   2a diagrammatically shows the reading electronics of the inspection system according to FIG.

Figure 2b   2b diagrammatically shows the reading electronics of the inspection system according to FIG.

3 graphically illustrates the pulse processing performed by the reading electronics described in FIG.

FIG. 4 is a diagram of a multi-channel read circuit for use with the inspection system described in FIG.

[Figure 5]   FIG. 5 is an X-ray diffraction diagram in a conventional system for baggage scanning.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Darmody Gelend Spencer             UK Kent TNT 14 7 Bee             Peaven Oaks Fort Hals             Ted DRR (72) Inventor Boyd Andrew James             UK Kent TNT 14 7 Bee             Peaven Oaks Fort Hals             Ted DRR (72) Inventor Burroughs John David             UK Kent TNT 14 7 Bee             Peaven Oaks Fort Hals             Ted DRR F-term (reference) 2G001 AA01 BA18 CA01 DA01 DA08                       DA10 EA03 GA13

Claims (10)

[Claims] Over 1. A corner range phi ₀ -.phi _d, a detection system 60 for detecting the quasi-monochromatic or polychromatic X-rays 12 are scattered by the target material 14, the angle range phi ₀ -.phi _d Corresponding to each of the semi-conductive detector elements 16a, b ,. ． ． The detector device element 16a comprises an array 16 of band gap transmissions responsive to X-ray irradiation (
made of a semiconducting material with a band gap transport, whereby each detector element 16a produces an electrical reaction with a magnitude dependent on the incident X-ray energy, and each read channel 24a is Front end electronics 44, 46 arranged to convert a semiconductor electrical response into electrical pulses 72a-h with a parameter indicative of the magnitude of the response; said pulse parameters being first ε ₁ and second digital signals 74a, c when they are between the preselected discriminator values of ε _2.
, E, g, h arranged to output discrimination electronics 48, 50, and a counter 52 arranged to count the number of digital signals output from the discrimination electronics 48, 50. The detection system, comprising: 2. The detector system 60 of claim 1, at least
Also includes two arrays of read channels, each semiconducting detector element 16a, b ,. ．
． Are connected to a separate read channel, one from each array, and
The read channel 24a in FIG.₁And the second ε₂ With the discrimination electronics 48, 50 set to the value of the discriminator, which is similar
And the appropriate discriminator value ε for the read channels 80a, 82a in the other array. ₃ , Ε_FourThe system as described above, characterized in that 3. The detection device system 60 according to claim 1, wherein:
Each detector element 16a, b, c, .. in array 16 plotted against the number of counts 74a registered in each connected read channel 24a. ．
． System, also comprising display means arranged to display the X-ray scattering patterns 28, 30 for each reading array 24 extracted from the position. 4. The detection device system 60 according to claim 1, 2, or 3, wherein the semiconducting elements 16a, 16b, 16c are cadmium zinc telluride, gallium arsenide, lead iodide, or Said system, characterized in that it is manufactured from mercury iodide. 5. The detection system according to the preceding paragraphs, wherein the angular range φ _{0 to} φ _d is 2 degrees to 8 degrees. 6. An x-ray source, a target substance to be investigated 14, and a quasi-monochromatic or polychromatic x-ray beam produced by said source arranged to be scattered from said target substance into said detection system. An X-ray inspection system 10 having a detection system, comprising the detection system 60 according to any one of claims 1 to 5. 7. The X-ray inspection system 10 of claim 6, wherein the quasi-monochromatic or polychromatic X-ray beam illuminates a coplanar two-dimensional array of voxels within the material of interest. , And is collimated into a fan beam, and the system 10 only collects X-rays scattered from a single voxel 14 at a depth and height in the illuminated array. Said system, characterized in that it comprises focus collimating means arranged to pass to a detection system 60. 8. The X-ray inspection system 10 of claim 7, wherein the system 10 includes an array of focus collimating means and a separate array of detection systems, wherein the collimating array members are , The X-rays scattered from the individual voxels 14 at different heights in the illuminated voxel array are stacked for simultaneous transmission to individual detection systems 60. 9. The X-ray inspection system 10 of claim 8, wherein the array of collimating means enables detection of X-rays scattered from voxels 14 at different depths in the substance of interest. The system is characterized in that it is able to move relative to the substance of interest in the direction of unscattered X-rays. 10. The X-ray inspection system 10 of claim 6, wherein the X-ray inspection system is oriented symmetrically to intercept the cone-shaped distribution of diffracted X-rays in symmetrically equivalent regions. The system comprising a plurality of 16, 18, 20, 22 detection systems 60.