Identification of charge sharing in X-ray diffraction

Abstract

An X-ray diffraction device and a method for processing signals from the X-ray diffraction device are disclosed that can identify charge-sharing events and photon coincidence events by analyzing the time delay between first and second pulses generated by a first and second detector cell, respectively, and by analyzing the energies of the first and second pulses, respectively.

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for X-ray diffraction. [Background technology]

[0002] X-ray diffraction (XRD) analysis is performed by measuring the pattern of X-rays diffracted from a sample, most often in one dimension over a range of diffraction angles. One-dimensional (strip) or two-dimensional solid-state detectors allow measurements at several angles simultaneously, which speeds up the overall measurement process. Furthermore, the use of solid-state sensor materials and application-specific integrated circuits (ASICs) for sensor readout results in significantly lower noise levels, thus improving the resolution of the detected X-ray photon energy compared to older systems based on gas-filled detectors.

[0003] However, solid-state detectors such as 1D strip detectors can suffer from a problem called charge sharing, where a single X-ray photon triggers a response in two (usually adjacent) detector cells. When this occurs, the photon's energy can be split between the two cells, resulting in two lower-energy photons. This reduces the energy resolution of the XRD measurement.

[0004] It is known to try to address this problem by filtering out signals that occur at approximately the same time in two adjacent detector cells. In other words, if two detector cells respond at the same time, the system infers that charge sharing has occurred and both responses are ignored or not taken into account, i.e. the photon is not counted as arriving at either of the two cells.

[0005] The above-mentioned known techniques for rejecting coincident detector responses in adjacent detector cells introduce an additional problem: the possibility that two actual photons may arrive at adjacent detector cells simultaneously. This possibility increases at higher X-ray intensities (where the overall photon incidence rate is higher). The above-mentioned known rejection techniques result in poor count-rate linearity, especially at these higher intensities, because purely coincident photons are erroneously rejected as charge-sharing events. Summary of the Invention [Means for solving the problem]

[0006] According to an aspect of the present invention, there is provided an X-ray diffraction apparatus as set forth in claim 1.

[0007] Check the energy of each pulse and ensure both pulses have the correct energy (V L Exceeding V H By counting only events where the charge-sharing frequency is less than 100 kHz, the device can count coincident photons of the desired type of X-ray radiation while excluding charge-shared photons and excluding photons of other energies that are undesirably counted as part of the X-ray diffraction measurement.

[0008] The inventors have recognized that examining the energy of photons, rather than just their timing relationships, can help improve the linearity of the count rate. By distinguishing between charge-shared and exactly coincident photons based on energy, the device can reduce the number of exactly coincident photons that are erroneously not counted.

[0009] The inventors also recognized that examining the energy of each of the two pulses separately may enable better discrimination between coincident photons and charge-shared photons (and other unwanted photons). For example, the inventors recognized that examining the total energy detected in the two cells is not sufficient because the total energy may be susceptible to charge sharing caused by photons with higher energies than the X-ray photons of interest for diffraction measurements. Embodiments of the present invention seek to address this. By examining the energy of each pulse separately and setting upper and lower energy limits, the apparatus can filter out photons of (undesired) K-beta X-ray radiation, even when charge sharing occurs or when photons of (desired) K-alpha X-ray radiation arrive simultaneously at adjacent detector cells.

[0010] Examination of the individual pulse energies can improve robustness to noise compared to analysis of the total energy, because the noise in each signal can be additively combined when examining the total measurement (e.g., the sum of the two pulse energies). This also allows for a relatively simple approach and avoids unnecessary increases in circuit complexity.

[0011] The detector may be a solid state detector comprising a semiconductor material.

[0012] The first and second detector cells may be positioned adjacent to each other, i.e., at least with no other detector cells between them. (In some implementations, electrical components other than the detector cells may be positioned between the detector cells, but it is desirable to minimize the space between the detector cells.)

[0013] The detection processor may be provided as a separate component from the one or more readout circuits. The one or more readout circuits may be provided as one or more application specific integrated circuits (ASICs). The detection processor may be provided as a programmable processor such as a digital signal processor (DSP) or a reconfigurable processor such as a field programmable gate array (FPGA).

[0014] Not counting a charge-sharing event can mean that when the detection processor determines that a charge-sharing event has occurred, the detection processor does not count any of the pulses as arriving photons.

[0015] The first threshold may be selected to correspond to a photon energy less than the K-alpha emission line of the X-ray source. The second threshold may be selected to correspond to a photon energy greater than the K-alpha emission line of the X-ray source. Optionally, the second threshold may be selected to correspond to a photon energy less than the K-beta emission line of the X-ray source.

[0016] The detection processor, or one or more readout circuits, or both, detect the presence of the first and second pulses by detecting a detection threshold (V D ), in which case a pulse is detected only if its energy exceeds the detection threshold. The timing of each pulse (and thus the time delay between pulses) may be determined by reference to the detection threshold. For example, to determine the time delay between two pulses, the detection processor may compare the time at which a first pulse crosses the detection threshold with the time at which a second pulse crosses the detection threshold. (In this regard, either the rising or falling edge of each pulse may be considered.)

[0017] The inventors have discovered that it is desirable to set the first and second thresholds to define a relatively narrow energy "window" of characteristic X-ray energies of interest (e.g., K-alpha emission lines). This allows for the exclusion of unwanted X-ray energies. On the other hand, the inventors have found that it is advantageous to set the detection threshold at a relatively low level (near the noise floor) to detect and exclude charge sharing. By using detection thresholds that are different from the first and second thresholds, both of these benefits can be achieved simultaneously.

[0018] The energy of the pulse may be determined by measuring its amplitude, and therefore the first threshold, second threshold and detection threshold may each effectively be implemented as an amplitude threshold.

[0019] The readout signal or signals may be digital signals.

[0020] The one or more readout signals are generated for each detector cell to determine whether the pulse generated at that cell exceeds (i) a detection threshold (V D ) or (ii) the first threshold (V L ) or (iii) the second threshold (V H ) where the detection threshold is less than the first threshold, which is less than the second threshold.

[0021] For example, the readout signal may have two bits per detector cell, which encode the values ​​[0,1,2,3]. The value 0 (binary "00") may represent the absence of any detected pulse. The value 1 (binary "01") may represent a pulse that exceeds the detection threshold but does not reach the first threshold. The value 2 (binary "10") may represent a pulse that exceeds the first threshold but does not reach the second threshold, and the value 3 (binary "11") may represent a pulse that exceeds the second threshold. Of course, other encodings may also be used.

[0022] One or more readout circuits may periodically sample the output signals of each of the detector cells to generate one or more readout signals.

[0023] For each detector cell, the time period between successive samplings of that detector cell may be less than 600 ns, preferably less than 400 ns, and most preferably less than 200 ns. Frequent sampling is desirable to enable precise detection of multiple photon coincidences.

[0024] The time period between successive samples may be at least 10 ns, alternatively at least 20 ns, 50 ns, 100 ns or 150 ns. Excessively frequent sampling may have the drawback that a large amount of redundant data is collected.

[0025] The detector may include a third detector cell and a fourth detector cell configured to convert incoming X-ray photons into electrical pulses, respectively. The one or more readout circuits include a first readout circuit and a second readout circuit each coupled to the detector. The first readout circuit is configured to receive the electrical pulses from the first and third detector cells and generate a first readout signal for the detection processor. The second readout circuit is configured to receive the electrical pulses from the second and fourth detector cells and generate a second readout signal for the detection processor.

[0026] In this way, the detection processor does not count charge-sharing events that occur between cells that are read by different readout circuits, which is an advantage of performing the coincidence detection process separately from the readout circuits.

[0027] The detection processor may be configured to analyze a third pulse generated by the third detector cell and a fourth pulse generated by the fourth detector cell based on the first readout signal and the second readout signal. determining that one of a charge sharing event and a photon coincidence event has occurred if the time delay between the third pulse and the fourth pulse is less than a predetermined time threshold; and The energy of each of the third and fourth pulses is equal to or exceeds the first threshold (V L ) and the second threshold (V H ), it is determined that a photon coincidence event has occurred, otherwise it is determined that a charge sharing event has occurred. Including, Furthermore, the detection processor is configured to count photon coincidence events as X-ray photon arrivals at the third and fourth detector cells, respectively, and not count charge-sharing events.

[0028] The third detector cell may be positioned adjacent to the fourth detector cell in the detector, and the second detector cell may be positioned between the first detector cell and the third detector cell in the detector.

[0029] The detector may be a one-dimensional strip detector.

[0030] A method for processing signals from an X-ray diffraction instrument as claimed in claim 8 is also disclosed.

[0031] There is also provided a computer program comprising computer program code, the computer program code being configured, when the program is run on one or more physical computing devices, to cause the one or more physical computing devices to perform all of the steps of a method according to an embodiment.

[0032] The computer program may be embodied on a computer-readable medium, which may be a non-transitory computer-readable medium. The invention will now be described, by way of example only, with reference to the accompanying drawings in which: [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a schematic diagram of an X-ray diffraction apparatus according to an embodiment. [Figure 2] FIG. 2 is a block diagram illustrating the readout circuitry and detection processor of the device of FIG. 1; [Figure 3] FIG. 1 is a schematic diagram of charge sharing and photon coincidence events. [Figure 4] FIG. 3 is a block diagram illustrating the readout of a single detector cell in the detector of FIGS. 1 and 2; [Figure 5] 1 illustrates how pulses generated by a detector cell can be distinguished by their amplitude. [Figure 6] FIG. 10 is a block diagram illustrating a readout circuit and detection processor in another embodiment. [Figure 7] 1 is a flowchart illustrating a method according to an embodiment. [Figure 8] 10 is a flowchart illustrating a further method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] It should be noted that these figures are schematic and are not drawn to scale: the relative dimensions and proportions of some of the figures have been exaggerated or reduced in size for clarity and convenience in the drawings.

[0035] It should be noted that the word "sample" is used in two specific and different contexts in this document. On the one hand, it is used as a noun to refer to the physical "sample" (or specimen) under investigation in an X-ray diffraction measurement. On the other hand, it is used as a verb to refer to the step of "sampling" an analog signal, performed, for example, during an analog-to-digital conversion process. It is believed that the meaning of the word in each case will be clear in light of the context of its use.

[0036] FIG. 1 illustrates an X-ray diffraction instrument 100 according to one embodiment. The instrument includes an X-ray source 110, which in this embodiment is an X-ray tube. The instrument further includes a sample stage 120, which supports a sample holder 122, which holds a sample 130. X-ray source 110 emits X-rays in an incident beam 112 that irradiates sample 130. Sample 130 diffracts the X-rays, producing a diffracted beam 114. A detector 140 is provided that is configured to receive and detect the X-rays diffracted from the sample in diffracted beam 114.

[0037] 2 is a block diagram of an apparatus configured to process the output of the detector 140. A first readout circuit 210a and a second readout circuit 210b are coupled to the detector 140. The two readout circuits 210a, 210b communicate with a detection processor 230 configured to process the signals generated by the readout circuits. In this embodiment, the detection processor 230 is implemented as a programmable microprocessor, which allows the detection process to be defined at least in part in software or firmware. This allows for increased adaptability by making the process reconfigurable for a variety of different applications and measurements.

[0038] Before describing the operation of the device in more detail, we will first explain the problem of charge sharing and coincident photons with reference to Figure 3. Figure 3 shows five X-ray photons 114a-114e of diffracted beam 114 incident on detector 140. The detector has N detector cells 1421-1422. N Each of the detector cells 1421 to 142 N are the respective detection elements 1441 to 1444 N In this embodiment, detector 140 is a microstrip detector, with each detector element being a strip electrode. As each photon 114a-114e arrives, a charge cloud (represented by the shaded gray triangles 116a-116e) is generated. The charge cloud is sensed by detector elements 144, which convert the incoming X-ray photons into electrical pulses.

[0039] For the first photon 114a, there is essentially no problem, since all of the converted charges 116a are collected by a single strip of a single detector cell 1422. The resulting charges will be transferred to a single preamplifier, and the corresponding signal can be interpreted as the signal for just one photon, and therefore represents the energy of that photon (see below, see FIG. 4).

[0040] The charge 116b generated by the second photon 114b is shared between detector cells 1424 and 1425 and will be sensed by their respective strips (i.e., detection elements). The charge collected by each strip represents a fraction of the energy of the incoming photon. This makes it impossible to estimate the photon's energy when considering a single channel, which leads to a loss of energy resolution and a bias towards lower energies. The same phenomenon occurs for the charge 116c generated by the third photon 114c. This charge is shared between detector cells 1427 and 1428.

[0041] The challenge posed can be illustrated by considering an example in which the x-ray source 110 is a tube using a copper (Cu) anode. This tube delivers characteristic energies of 8 keV (K-alpha) and 8.9 keV (K-beta). If the strip detector had good intrinsic energy resolution (full width at half maximum < 400 eV @ 8 keV), it should be possible to measure only 8 keV photons by recording only events between 7.6 and 8.4 keV (for example). However, if an 8.9 keV photon were charge-shared between two channels, one channel could receive a charge equivalent to an 8 keV signal and the adjacent channel could receive a charge equivalent to a 0.9 keV signal. If the system could determine that both of these events occurred simultaneously, it could infer that this photon must have had an energy different from the desired 8 keV energy and could therefore be discarded.

[0042] On the other hand, as already mentioned above, examining only the timing of incidence to rule out charge sharing becomes a disadvantage, especially at higher intensities. Although the probability of two 8 keV photons arriving at two adjacent strips at the same time increases, these valid events would be discarded due to coincidence, according to the logic mentioned above. This means that the count rate linearity is significantly reduced at high count rates. The example described below attempts to mitigate this phenomenon. Figure 3 shows the timing of two adjacent detector cells 142. N-1 and 142 N Also shown are two coincident photons 114d and 114e arriving at approximately the same time at the same time. It would be desirable to detect and count these photons rather than (incorrectly) disregarding them as charge-sharing events.

[0043] 4 is a schematic diagram of a single channel of one of the readout circuits 210 in one embodiment. In this embodiment, the readout circuit 210 is implemented as an ASIC coupled to the detector 140. The detector element 144 of the detector cell i of interest iis depicted as a diode. Corresponding channel i of the ASIC readout circuit 210 includes a charge-sensing preamplifier 212 with a fixed gain and a shaping filter 214. The preamplifier 212 and shaping filter 214 make up the analog front end. The shaping filter 214 has a time constant that affects the duration of the pulse output by the analog front end. In some embodiments, there may be several selectable time constants (or selectable shaping filters with different time constants), which can be selected depending on the required energy resolution and the required count rate of the detected photons. The shorter output pulses required for higher count rates typically contain more electronic noise, resulting in poorer energy resolution. After the analog front end, the energy of the detected photon is evaluated by passing the voltage pulse generated by the detected photon through three comparators 216, 217, and 218. The comparators detect whether the pulse height crosses a threshold level, thereby digitizing the pulse amplitude (which correlates to the photon energy). The first comparator 216 compares the pulse amplitude with a first threshold V L The second comparator 217 compares the pulse amplitude with a second threshold V H The third comparator 218 compares the pulse amplitude with a third threshold, a detection threshold V D As shown in Figure 5, the detection threshold V D is the first threshold V L is lower than the first threshold V L is the second threshold V H Each of the thresholds may be configurable. Alternatively, some or all of the thresholds may be fixed and may be hardwired into an ASIC design, for example. The information digitized by the comparators is transferred by the digital section 220 from the readout circuit 210 to the detection processor 230.

[0044] FIG. 5 illustrates detecting different pulse amplitudes using the circuit of FIG. 4. Pulse 1 is detected above a first threshold V L , but the second threshold V HThis is the energy range of interest (e.g., the K-alpha energy of an X-ray source). Pulse 2 does not exceed the second threshold V H This would be the case for example with unwanted K-beta radiation. Pulse 3 is above the detection threshold V D , and is therefore detected as a pulse. However, the first threshold V L In this example, pulse 1 will be counted, but pulses 2 and 3 will not be counted (i.e., will be ignored and not counted).

[0045] Note that the above example does not describe the exact connections between the individual detector cells 142 and the two readout circuits 210a and 210b. This is because the device is generally not limited to any particular connection arrangement. Using two readout circuits increases the bandwidth for reading data from the detector 140. This highlights the advantage of performing detection processing in a detection processor 230 separate from one or more readout circuits 210. The detection processor 230 has access to data from all of the detector cells because it is connected to both of these readout circuits 210. In contrast, each individual readout circuit 210a, 210b processes signals from only a subset of the detector cells. Therefore, each readout circuit 210a, 210b can only detect charge sharing between its assigned detector cells.

[0046] 6 shows an embodiment in which the detection processor 230 is configured to detect charge sharing between adjacent detector cells, where the signals of the adjacent detector cells are handled by different readout circuits 210. In this embodiment, a first detector cell 3421 and a third detector cell 3423 are connected to a first readout circuit 210a. A second detector cell 3422 and a fourth detector cell 3424 are connected to a second readout circuit 210b. The second detector cell is positioned adjacent to and between the first and third detector cells. The third detector cell is positioned adjacent to and between the second and fourth detector cells.

[0047] A method performed by XRD apparatus 100 will now be described with reference to the flow chart of Figure 7. The method of this example applies to the readout arrangement illustrated in Figure 6, but more generally to any readout arrangement, such as that shown generally in Figure 2.

[0048] In step 610, the detection processor 230 receives the read signal from the read circuit 210. In this embodiment, the read circuits 210a, 210b are each implemented as an ASIC, and the detection processor 230 is implemented as a programmable microprocessor. Referring to Figure 4, the read signal is a digital signal, as described above. In particular, the read circuits 210 each generate a two-bit output for each channel. The two bits can encode four levels, and below we show each case separately for the pulse amplitude. (i) When there is no pulse, i.e., the amplitude is not above the detection threshold (ii) if there is a pulse and its amplitude is above the detection threshold but below the first threshold; (iii) a pulse is present and its amplitude is above the first threshold but below the second threshold; or (iv) If there is a pulse and its amplitude exceeds the second threshold

[0049] There are a total of 128 channels per readout circuit. Therefore, the number of detector cells is 256 (128 x 2). Each readout circuit 210 provides a 16-bit output at a clock rate of 100 MHz. Each channel is multiplexed into 16 groups of 8, meaning that each 16-bit output consists of 8 x 2-bit digital values. For each readout circuit 210, 16 groups of channels are output over 16 clock cycles. Two additional clock cycles are used for synchronization / handshaking with the detection processor 230, giving a total period of 18 cycles (180 ns) between successive samples from the same detector cell appearing in the readout signal. A high sampling rate is desirable to ensure accuracy in determining whether two pulses from adjacent cells occur at approximately the same time.

[0050] Assume that a first detector cell 1427 generates a first pulse of amplitude V1 and a second detector cell 1428 generates a second pulse of amplitude V2.

[0051] In step 620, the detection processor 230 determines whether the amplitudes V1 and V2 of the first and second pulses, respectively, are greater than or equal to the detection threshold V D If both amplitudes are above the detection threshold, the detection processor 210 detects the presence of the first and second pulses (step 630). Once it is certain that there are two pulses to consider, the detection processor 230 next evaluates (in step 640) whether the time delay Δt between the two pulses is less than a predetermined time threshold T. If so, the detection processor treats the two pulses as occurring approximately simultaneously. In this embodiment, pulses are treated as occurring approximately simultaneously if they are detected in the read signal within 640 ns of each other.

[0052] Note that charge sharing causes the pulses to occur simultaneously in the two detector cells, but slight timing differences occur due to digitization in the readout circuitry 210. As noted above, each group of channels is continuously sampled and readout over a 180 ns period. Furthermore, when pulses are measured by comparison to a threshold amplitude, the exact instant at which the pulse crosses the threshold is subject to jitter that depends on the amplitude of the pulse. As a result, in practice, to detect nearly simultaneous pulses, the detection processor 230 must consider a finite range of time differences.

[0053] The given time threshold T is related to the pulse duration. This pulse duration depends on the time constant of the shaping filter integrated after the preamplifier. In this embodiment, the device has four selectable time constants of the filter. The time threshold T should be approximately as long as the maximum possible time difference between two pulses generated by charge-shared photons. Furthermore, jitter due to digital readout should be added. Therefore, a fast digital readout is desirable. When changing the time constant of the shaping filter, the time threshold T should be adapted correspondingly (since the maximum possible time difference between charge-shared pulses is correlated with the time constant of the shaping filter). In this embodiment, good results were obtained with a time threshold T = 640 ns and a time constant of 1.1 μs for the pulse-shaping filter. This constant is the rise time for the pulse to reach its peak value (and the pulse needs approximately the same time to settle down again). In practice, the detection threshold V D is not at zero level, the time threshold T is set to be smaller than this time constant. The time threshold T can be easily modified and adjusted accordingly depending on the level of the detection threshold.

[0054] For completeness, it should be noted that in this embodiment, readout circuitry 210 detects each pulse on its falling (trailing) edge, rather than its rising (leading) edge. That is, comparators 216-218 are triggered when the pulse exceeds its respective threshold and then drops below it again in amplitude. The time delay between pulses is determined based on when the falling edge of each pulse crosses below the detection threshold again.

[0055] If, in step 640, it is determined that the time delay Δt is less than the threshold time T, then (in step 650) detection processor 230 determines that either a charge-sharing event or a photon coincidence event has occurred. To distinguish between these two possibilities, detection processor 230 evaluates the pulse amplitudes against first and second thresholds. Specifically, in step 660, detection processor 230 evaluates whether the amplitudes of both the first and second pulses are greater than the first threshold and less than the second threshold. If this is found to be the case, detection processor 230 determines that a photon coincidence event has occurred (step 670). That is, two photons arrived at adjacent detector cells at approximately the same instant. On the other hand, if, in step 660, it is determined that the amplitudes of the first and second pulses are not both between the first and second thresholds, then detection processor 230 determines that a charge-sharing event has occurred (step 680). That is, charge generated by at least one photon has been collected by two adjacent detector cells.

[0056] If detection processor 230 determines that a photon coincidence event occurred, then both pulses are counted as photons (step 675). If detection processor 230 determines that a charge-sharing event occurred, then neither pulse is counted as a photon (step 685).

[0057] The first and second thresholds may be selected to accept as coincident X-ray photons only those with the desired K-alpha characteristic transition energy, thereby maximizing the rejection of charge-sharing events and the rejection of unwanted X-ray energy at high intensities while minimizing loss of count rate linearity.

[0058] If Δt>T, then if the pulse is inside the energy window (V L Larger and V H Note that if T is less than T, the pulses are considered to be caused by separate events and are counted. The coincidence check is performed around each pulse, during a time T before the pulse and during a time T after the pulse. In this example, the check considers events only in adjacent cells.

[0059] A specific embodiment of the method will now be described with reference to the apparatus of Figure 6. As discussed above, in Figure 6, the first readout circuit 210a reads out the first and third pulses from the first and third detector cells 3421 and 3423 and provides a first readout signal to the detection processor 230. The second readout circuit 210b reads out the second and fourth pulses from the second and fourth detector cells 3422 and 3424 and provides a second readout signal to the detection processor 230. The detection processor 230 analyzes each pulse based on the first and second readout signals.

[0060] The first and second pulses are analyzed as described above with reference to Figure 7. The third and fourth pulses are analyzed as illustrated in Figure 8. Steps 620'-685' are similar to steps 620-685, respectively, in Figure 7, except that the third and fourth pulses are evaluated instead of the first and second pulses. A similar analysis may be performed to compare and evaluate the second pulse from the second detector cell and the third pulse from the third detector cell.

[0061] The above examples illustrate some of the benefits of using a detection processor provided separately from one or more readout circuits. This allows the detection processor 230 to be easily programmed or reconfigured. Furthermore, this allows the detection processor 230 to evaluate possible charge sharing in all associated sets of detector cell pairs, regardless of whether each cell is read out by the first readout circuit 210 a or the second readout circuit 210 b.

[0062] Variations can be made to the above-described embodiments without departing from the scope of the present disclosure. Below are some non-exhaustive examples of possible variations:

[0063] The time of a pulse may be determined by its rising edge or its falling edge. In the above example, the readout circuit detected a pulse when the signal amplitude was at least above the detection threshold and then below this threshold again. In other words, each pulse was detected by its falling edge. Alternatively, a pulse can be detected by its rising edge.

[0064] The above description has focused on examples of charge sharing between adjacent detector cells, but the invention is not necessarily limited in this respect. Depending on the size and placement of the detector cells, it is possible that charge sharing can occur between detector cells that are not immediately adjacent.

[0065] In the above embodiment, there were two readout circuits 210a and 210b. However, it will be understood that this is not required. In other embodiments, there may be more than two readout circuits 210, or there may be only a single readout circuit 210.

[0066] In the above examples, the detector was a one-dimensional strip detector, however the same principles can be applied to the detection and exclusion of charge sharing in XRD measurements using two-dimensional solid-state detectors.

[0067] It is not necessary that the X-ray source be a copper source. Other sources will be known to those skilled in the art of XRD. Similar considerations and analysis apply to these other sources.

[0068] It should be noted that the above-mentioned embodiments illustrate rather than limit the present invention, and that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The embodiments may also be implemented by means of hardware comprising several distinct elements. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that several means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. Furthermore, in the appended claims, a list containing "at least one of A, B, C" should be interpreted as meaning (A or B or C) or any combination thereof.

[0069] Moreover, in general, various embodiments may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing element. These are not limiting examples. While various aspects described herein may be illustrated and described using block diagrams, flowcharts, or other graphical representations, it will be appreciated that these blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controllers or other computing elements, or any combination thereof, as non-limiting examples.

[0070] The embodiments described herein may be implemented by computer software executable by a data processor of the apparatus, such as in a detection processor entity, or by hardware, or by a combination of software and hardware. Furthermore, in this regard, it should be noted that any of the blocks of logic flow as depicted in the figures may represent program steps, interconnected logic circuits, blocks and functions, or combinations of program steps, logic circuits, blocks and functions. Software may be stored on physical media, such as, for example, a memory chip, a memory block embodied within a processor, a magnetic medium such as a hard disk or floppy disk, a CD-ROM or DVD. D Optical media such as the above are also included.

[0071] The memory may be of any type appropriate to the local technology environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, removable memory, etc. The data processor may be of any type appropriate to the local technology environment and may comprise, by way of non-limiting example, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), gate-level circuits and processors based on multi-core processor architectures, etc.

[0072] Embodiments as discussed herein may be implemented in a variety of components, such as integrated circuit modules. The design of integrated circuits is generally a highly automated process. Complex and powerful software tools are available to convert logic-level designs into semiconductor circuit designs that can be etched onto semiconductor substrates.

Claims

1. An X-ray diffraction apparatus (100), an X-ray source (110); a sample stage (120) for receiving a sample to be irradiated by X-rays from the X-ray source; a detector (140) positioned to receive X-rays diffracted from the sample; one or more readout circuits (210) coupled to the detector; a detection processor (230) configured to process signals generated by the one or more readout circuits to count the number of photons arriving at the detector; Equipped with The detector (140) includes a first detector cell (142 ７ ;342 １ ) and a second detector cell (142 ８ ;342 ２ ) and each said detector cell is configured to convert each incoming X-ray photon into an electrical pulse; the first detector cell and the second detector cell are arranged such that no other detector cell is arranged between the first detector cell and the second detector cell; the one or more readout circuits (210) are configured to receive the electrical pulses from the first and second detector cells and generate one or more readout signals for the detection processor; the detection processor (230) is configured to analyze a first pulse generated by the first detector cell and a second pulse generated by the second detector cell based on the one or more readout signals; The detection processor: determining (650) that one of a charge-sharing event and a photon coincidence event has occurred if the time delay between the first pulse and the second pulse is less than a predetermined time threshold; and The energy of each of the first pulse and the second pulse is equal to or greater than a first threshold (V Ｌ ) and the second threshold (V Ｈ ), determine that a photon coincidence event has occurred (670); otherwise, determine that a charge sharing event has occurred (680). Including, Furthermore, the detection processor counting (675) the photon coincidence events as arrival of X-ray photons at each of the first and second detector cells; Do not count the charge sharing event (685) It is configured as follows: Device.

2. 10. The apparatus of claim 1, the one or more readout signals are digital signals; Device.

3. 3. The device according to claim 1 or 2, The one or more readout signals may be, for each detector cell, a pulse generated at that cell being: (i) Detection threshold (V Ｄ ) or (ii) the first threshold (V Ｌ ) or (iii) the second threshold (V Ｈ ) exceeded? This indicates that the detection threshold is less than the first threshold; The first threshold is smaller than the second threshold. Device.

4. The device according to any one of claims 1 to 3, the one or more readout circuits (210) periodically sample the output signals of each of the detector cells (142) to generate the one or more readout signals; Device.

5. The device according to any one of claims 1 to 4, The detector (140) includes a third detector cell (342 ３ ) and the fourth detector cell (342 ４ ) and The third detector cell (342 ３ ) and the fourth detector cell (342 ４ ) configured to convert each incoming X-ray photon into an electrical pulse; the one or more readout circuits include a first readout circuit (210a) and a second readout circuit (210b); a first readout circuit (210a) and a second readout circuit (210b) each coupled to the detector (140); The first readout circuit (210a) reads the first and third detector cells (342 １ , 342 ３ ) configured to receive electrical pulses from the detector (230) and generate a first readout signal for the detection processor (230); The second readout circuit is connected to the second and fourth detector cells (342 ２ , 342 ４ ) to generate a second readout signal for the detection processor (230). Device.

6. 6. The apparatus of claim 5, The third detector cell (342 ３ ) in the detector, the fourth detector cell (342 ４ ) positioned adjacent to Device.

7. The device according to any one of claims 1 to 6, the detector (140) is a one-dimensional strip detector; Device.

8. 1. A method for processing a signal from an X-ray diffraction apparatus (100), comprising: the apparatus comprising a detector (140) positioned to receive X-rays diffracted from the sample; The detector includes a first detector cell (142 ７ ;342 １ ) and a second detector cell (142 ８ ;342 ２ ) and each said detector cell is configured to convert each incoming X-ray photon into an electrical pulse; the first detector cell and the second detector cell are arranged such that no other detector cell is arranged between the first detector cell and the second detector cell; The method comprises: acquiring (610) one or more readout signals depicting a first pulse generated by the first detector cell and a second pulse generated by the second detector cell; analyzing the first pulse and the second pulse based on the one or more readout signals, determining (650) that one of a charge sharing event and a photon coincidence event has occurred if the time delay between the first pulse and the second pulse is less than a predetermined time threshold; The energy of each of the first pulse and the second pulse is equal to or greater than a first threshold (V Ｌ ) and the second threshold (V Ｈ ), determining that a photon coincidence event has occurred (670); otherwise, determining that a charge sharing event has occurred (680); and Including, The method counting the photon coincidence events as arrival of X-ray photons at each of the first and second detector cells (675); Not counting the charge sharing events (685). further comprising: method.

9. 9. The method of claim 8, the one or more readout signals are digital signals; method.

10. 10. The method of claim 8 or 9, The one or more readout signals may be, for each detector cell, a pulse generated at that cell being: (i) Detection threshold (V Ｄ ) or (ii) the first threshold (V Ｌ ) or (iii) the second threshold (V Ｈ ) exceeded? This indicates that the detection threshold is less than the first threshold; The first threshold is smaller than the second threshold. method.

11. 1. A computer program comprising computer program code, When the program is executed on one or more physical computing devices, The computer program code is configured to cause the one or more physical computing devices to perform all of the steps of any one of claims 8 to 10. Computer program.

12. 12. A computer program according to claim 11, comprising: A computer program embodied on a computer-readable medium.

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