JP7828238B2 - Radiation detection device, information processing method, and computer program - Google Patents

Description

The present invention relates to a radiation detection device, an information processing method, and a computer program for detecting radiation.

Some radiation detectors that detect radiation such as X-rays are equipped with a radiation detection element that uses a semiconductor. When radiation is incident on the radiation detection element, an amount of charge corresponding to the energy of the radiation is generated within the semiconductor, generating a signal corresponding to the amount of charge, and producing a radiation spectrum that shows the relationship between the number of generated signals and the energy of the radiation. In addition to peaks caused by the radiation to be detected, the radiation spectrum also contains so-called system peaks caused by characteristic X-rays generated within the radiation detector. In order to improve the accuracy of radiation detection, it is necessary to reduce the system peaks. Patent Document 1 discloses a technique for subtracting the background caused by the system peaks from the radiation spectrum.

JP 2011-99749 A

In Patent Document 1, a constant is subtracted from the spectrum to represent the background caused by the system peak. However, it is difficult to appropriately reduce the system peak using the method of subtracting a constant. Another method for reducing the system peak is to shield the characteristic X-rays generated within the radiation detector. However, it is not possible to shield the characteristic X-rays generated from parts near the surface of the radiation detection element, such as the protective film, and a system peak is generated due to these characteristic X-rays.

The present invention was made in consideration of these circumstances, and its purpose is to provide a radiation detection device, information processing method, and computer program that can appropriately reduce system peaks.

One aspect of the present invention provides a radiation detection device comprising a radiation detection element having a semiconductor portion and an information processing unit. The information processing unit calculates the spectrum of radiation incident on the object in a specific band in which radiation that generates characteristic X-rays is absorbed by the object based on the spectrum of radiation incident on the semiconductor portion, the radiation absorption characteristics of the object depending on the components of the object through which the radiation passes before entering the semiconductor portion, and the amount of material through which the radiation passes in the object; calculates a system peak by calculating the spectrum of the characteristic X-rays generated from the object and incident on the semiconductor portion based on the calculated spectrum, the characteristic X-ray generation characteristics of the object depending on the components of the object, and the amount of material; and subtracts the calculated system peak from the spectrum of radiation incident on the semiconductor portion.

In one aspect of the present invention, the radiation detection device calculates the spectrum of radiation incident on an object based on the spectrum of radiation incident on a semiconductor portion included in a radiation detection element, the components of the object through which the radiation passes before entering the semiconductor portion, and the amount of material in the object through which the radiation passes. The radiation detection device also calculates a system peak based on the spectrum of radiation incident on the object, the components of the object, and the amount of material in the object through which the radiation passes, and subtracts the system peak from the radiation spectrum. In this way, the radiation detection device corrects the radiation spectrum by subtracting the system peak from the radiation spectrum. The radiation detection device can obtain a system peak of appropriate intensity by calculating a system peak according to the components of the object through which the radiation passes before entering the semiconductor portion and the amount of material in the object through which the radiation passes.

In one aspect of the radiation detection device of the present invention, the radiation detection element further has a surface layer that exists between the incident surface onto which radiation is incident and the semiconductor portion, and the information processing unit calculates the spectrum of the radiation incident on the surface layer in a specific band in which radiation that generates characteristic X-rays is absorbed by the surface layer based on the spectrum of the radiation incident on the semiconductor portion, the radiation absorption characteristics of the surface layer depending on the components of the surface layer, and the thickness of the surface layer, calculates the spectrum of the characteristic X-rays emitted from the surface layer based on the calculated spectrum, the characteristic X-ray generation characteristics of the surface layer depending on the components of the surface layer, and the amount of material in the surface layer through which radiation passes, and calculates the spectrum of the characteristic X-rays incident on the semiconductor portion based on the spectrum of the characteristic X-rays emitted from the surface layer, thereby calculating the system peak.

In one aspect of the present invention, radiation passes through a surface layer included in the radiation detection element before entering the semiconductor portion. The radiation detection device calculates the spectrum of radiation incident on the surface layer based on the spectrum of radiation incident on the semiconductor portion and the components and thickness of the surface layer. The attenuation of radiation in the surface layer can be calculated according to the components and thickness of the surface layer, and the spectrum of radiation incident on the surface layer can be calculated from the spectrum of radiation incident on the semiconductor portion. The radiation detection device calculates characteristic X-rays emitted from the surface layer based on the spectrum of radiation incident on the surface layer, the components of the surface layer, and the amount of material in the surface layer through which the radiation passes, and calculates the spectrum of the characteristic X-rays incident on the semiconductor portion, thereby calculating the system peak. The thickness of the surface layer can be used as the amount of material in the surface layer through which the radiation passes. The spectrum of characteristic X-rays generated in the surface layer by the radiation can be calculated from the spectrum of radiation incident on the surface layer and the components and thickness of the surface layer, and the system peak can be obtained.

In one aspect of the radiation detection device of the present invention, the surface layer is composed of multiple layers, and the information processing unit calculates the spectrum of radiation incident on each layer based on the order of the multiple layers, the radiation absorption characteristics of each layer depending on the composition of each layer, and the amount of material in each layer through which radiation passes; calculates the spectrum of characteristic X-rays generated from each layer based on the spectrum of radiation incident on each layer, the characteristic X-ray generation characteristics of each layer depending on the composition of each layer, and the amount of material in each layer through which radiation passes; and calculates the spectrum of characteristic X-rays from each layer incident on the semiconductor portion based on the spectrum of characteristic X-rays generated from each layer, the order of the multiple layers, the radiation absorption characteristics of each layer depending on the composition of each layer, and the amount of material in each layer through which characteristic X-rays from other layers pass.

In one embodiment of the present invention, the surface layer is made up of multiple layers. The spectrum of the radiation incident on each layer and the spectrum of the characteristic X-rays generated in each layer are determined depending on the order of the multiple layers, the components of each layer, and the amount of material through which radiation penetrates in each layer. The radiation detection device can calculate the system peak caused by the characteristic X-rays by calculating the characteristic X-rays generated in each layer and incident on the semiconductor portion.

A radiation detection device according to one aspect of the present invention further includes a housing that houses the radiation detection element, the housing having an unblocked opening, the radiation detection element being disposed with the incident surface facing the opening, and the surface layer including a light-shielding film.

In one embodiment of the present invention, the radiation detection element is housed in a housing, which has an opening that is not blocked by a window material, and radiation that passes through the opening enters the radiation detection element and is detected. The radiation detection device can detect radiation that is too low in energy to pass through the window material. The surface layer includes a light-shielding film, which prevents light from entering the interior of the radiation detection element. The radiation detection device can obtain a radiation spectrum with reduced system peaks caused by the light-shielding film through information processing.

In one aspect of the radiation detection device of the present invention, the light-shielding film is made of aluminum, carbon, gold, beryllium, magnesium, or an alloy thereof.

In one embodiment of the present invention, the light-shielding film is made of aluminum, carbon, gold, beryllium, magnesium, or an alloy thereof. Such a light-shielding film effectively prevents light from entering the interior of the radiation detection element. This prevents noise caused by light.

A radiation detection device according to one aspect of the present invention further includes a radiation detector including the radiation detection element, and the information processing unit calculates the spectrum of the characteristic X-rays incident on the semiconductor portion using a correction coefficient specific to the radiation detector.

In one aspect of the present invention, the radiation detection device calculates the spectrum of characteristic X-rays incident on the semiconductor portion using a correction coefficient specific to the radiation detector. The correction coefficient is a coefficient for correcting the intensity of characteristic X-rays incident on the semiconductor portion according to the configuration of the radiation detector. By using the correction coefficient, it is possible to accurately calculate the system peak caused by characteristic X-rays.

A radiation detection device according to one aspect of the present invention further comprises an irradiation unit that irradiates a sample with radiation, and a display unit that displays the spectrum of the radiation after the system peak has been subtracted.

In one aspect of the present invention, a radiation detection device includes an irradiation unit and detects radiation, such as fluorescent X-rays, generated from a sample irradiated with radiation. Based on the spectrum of radiation with reduced system peaks, analysis of elements contained in the sample can be performed with high precision. The radiation detection device displays the spectrum of radiation with reduced system peaks on a display unit. The user can confirm the spectrum of radiation with reduced system peaks.

An information processing method according to one aspect of the present invention includes calculating the spectrum of radiation incident on an object in a specific band in which radiation that generates characteristic X-rays is absorbed by the object based on the spectrum of radiation incident on a semiconductor portion of a radiation detection element, the radiation absorption characteristics of the object that depend on the components of the object through which the radiation passes before entering the semiconductor portion, and the amount of material through which the radiation passes in the object; calculating the spectrum of the characteristic X-rays generated from the object and incident on the semiconductor portion based on the calculated spectrum, the characteristic X-ray generation characteristics of the object that depend on the components of the object, and the amount of material; and calculating a system peak by subtracting the calculated system peak from the spectrum of radiation incident on the semiconductor portion.

A computer program according to one embodiment of the present invention causes a computer to perform the following processing: calculate the spectrum of radiation incident on an object in a specific band in which radiation that generates characteristic X-rays is absorbed by the object, based on the spectrum of radiation incident on a semiconductor portion of a radiation detection element, the radiation absorption characteristics of the object that depend on the components of the object through which the radiation passes before entering the semiconductor portion, and the amount of material through which the radiation passes in the object; calculate the spectrum of the characteristic X-rays generated from the object and incident on the semiconductor portion based on the calculated spectrum, the characteristic X-ray generation characteristics of the object that depend on the components of the object, and the amount of material; and calculate a system peak by subtracting the calculated system peak from the spectrum of radiation incident on the semiconductor portion.

In one aspect of the present invention, the spectrum of radiation incident on an object is obtained based on the spectrum of radiation incident on a semiconductor portion included in a radiation detection element, the components of the object through which the radiation passes before entering the semiconductor portion, and the amount of material in the object through which the radiation passes. A system peak is calculated based on the spectrum of radiation incident on the object, the components of the object, and the amount of material in the object through which the radiation passes, and the system peak is subtracted from the radiation spectrum. An appropriate system peak is obtained depending on the components of the object through which the radiation passes before entering the semiconductor portion and the amount of material in the object through which the radiation passes. By subtracting the obtained system peak from the radiation spectrum, a radiation spectrum with an appropriately reduced system peak is obtained.

The present invention provides excellent effects, such as the ability to appropriately reduce system peaks from the spectrum of radiation detected using a radiation detection element.

FIG. 2 is a block diagram illustrating an example of the functional configuration of the radiation detection apparatus. 1 is a schematic cross-sectional view showing a first example of the configuration of a radiation detector. FIG. 10 is a schematic cross-sectional view showing a second example of the configuration of the radiation detector. 1 is a schematic cross-sectional view showing an example of a radiation detection element and a collimator. FIG. 2 is a block diagram showing an example of the internal configuration of an analysis device. 10 is a graph showing an example of the spectrum of radiation incident on a semiconductor portion. FIG. 4 is a conceptual diagram showing an example of the contents of characteristic data. 1 is a graph showing the relationship between absorption coefficient and radiation energy. 10 is a flowchart illustrating a first example of an information processing procedure for correcting a spectrum of radiation, which is executed by the analysis device. 10 is a graph showing an example of a spectrum of characteristic X-rays incident on a semiconductor portion. 10 is a graph showing the spectrum of corrected radiation. 10 is a flowchart illustrating a second example of an information processing procedure for correcting a spectrum of radiation, which is executed by the analysis device.

The present invention will now be described in detail with reference to the drawings showing embodiments thereof.
FIG. 1 is a block diagram showing an example of the functional configuration of a radiation detection apparatus 10. The radiation detection apparatus 10 is, for example, an X-ray fluorescence analysis apparatus. The radiation detection apparatus 10 includes an irradiation unit 35 that irradiates a sample 52 with radiation such as an electron beam or X-rays, a sample stage 51 on which the sample 52 is placed, and a radiation detector 2. Radiation is irradiated from the irradiation unit 35 to the sample 52, causing radiation such as fluorescent X-rays to be generated in the sample 52, and the radiation detector 2 detects the radiation generated from the sample 52. In the figure, the radiation is indicated by arrows. Note that the radiation detection apparatus 10 may also be configured to hold the sample 52 by a method other than placing it on the sample stage 51.

The radiation detector 2 includes a radiation detection element 1 and a preamplifier 21. A portion of the preamplifier 21 may be located inside the radiation detector 2, with the other portion located outside the radiation detector 2. The radiation detector 2 is connected to a signal processing unit 32 and a voltage application unit 31 that applies the voltage required for radiation detection to the radiation detection element 1. The signal processing unit 32 is connected to an analysis device 4. The voltage application unit 31, signal processing unit 32, irradiation unit 35, and analysis device 4 are connected to a control unit 33. The control unit 33 controls the operation of the voltage application unit 31, signal processing unit 32, irradiation unit 35, and analysis device 4. The analysis device 4 is connected to a display unit 34, such as a liquid crystal display or an electroluminescent display (EL display). The control unit 33 may be configured to receive user operations and control each component of the radiation detection device 10 in accordance with the received operations.

Figure 2 is a schematic cross-sectional view showing a first example of the configuration of a radiation detector 2. The radiation detector 2 is an SDD (Silicon Drift Detector). The radiation detector 2 includes a housing 25 shaped like a cylinder with a truncated cone connected to one end. The housing 25 is configured with a plate-like bottom plate covered with a cap-like cover. An opening 251 is formed at the tip of the housing 25. No window with a window material is provided in the opening 251, and the opening 251 is not blocked. The radiation detection element 1, collimator 22, circuit board 23, cooling unit 24, and cold finger 26 are arranged inside the housing 25. The housing 25 houses the radiation detection element 1, collimator 22, circuit board 23, and cooling unit 24. The cooling unit 24 is, for example, a Peltier element.

The radiation detection element 1 is mounted on the surface of the circuit board 23 and is positioned opposite the opening 251. The collimator 22 is cylindrical with open ends and is made of a radiation-shielding material. The collimator 22 is positioned between the radiation detection element 1 and the opening 251. One end of the collimator 22 faces the opening 251, and the other end faces the surface of the radiation detection element 1. Radiation mainly passes through the opening 251 and enters the inside of the housing 25, and the collimator 22 blocks some of the radiation. The radiation detection element 1 detects incident radiation that is not blocked by the collimator 22.

A circuit is formed on the circuit board 23, and the preamplifier 21 is mounted on it. The preamplifier 21 is omitted from Figure 2. The back surface of the circuit board 23 is in thermal contact with the heat absorption portion of the cooling section 24, either directly or via an intervening object. The heat dissipation portion of the cooling section 24 is in thermal contact with the cold finger 26. The cold finger 26 has a flat portion with which the heat dissipation portion of the cooling section 24 is in thermal contact, and a portion that penetrates the bottom plate of the housing 25. Heat from the radiation detection element 1 is absorbed by the cooling section 24 through the circuit board 23, conducted from the cooling section 24 to the cold finger 26, and dissipated to the outside of the radiation detector 2 through the cold finger 26.

The radiation detector 2 has multiple lead pins 27 that penetrate the bottom plate of the housing 25. The lead pins 27 are connected to the circuit board 23 by a method such as wire bonding. The voltage application unit 31 applies voltage to the radiation detection element 1, and the preamplifier 21 outputs a signal via the lead pins 27. The radiation detector 2 may further include other components.

Figure 3 is a schematic cross-sectional view showing a second example of the configuration of the radiation detector 2. In this second example, the radiation detector 2 does not include a cooling unit 24 or a cold finger 26. The back surface of the circuit board 23 is in thermal contact with the bottom plate of the housing 25, either directly or via an intervening object. Heat from the radiation detection element 1 is conducted to the bottom plate of the housing 25 through the circuit board 23 and is released from the bottom plate to the outside of the radiation detector 2. In this second example, radiation also mainly passes through the opening 251 to enter the inside of the housing 25 and then enters the radiation detection element 1.

Figure 4 is a schematic cross-sectional view showing an example of a radiation detection element 1 and a collimator 22. The radiation detection element 1 is a silicon drift type radiation detection element. The radiation detection element 1 is generally flat. The radiation detection element 1 includes a plate-shaped semiconductor portion 11 made of Si (silicon). The semiconductor portion 11 is composed of n-type Si. The radiation detection element 1 has an incident surface 151 located on the incident side where the radiation to be detected is incident, and an electrode surface 152 located on the back side of the incident surface 151. A portion of the incident surface 151 is covered by the collimator 22. The radiation detection element 1 is arranged so that the electrode surface 152 faces the circuit board 23 and the incident surface 151 faces the opening 251.

A surface layer 12 is provided in the portion of the radiation detection element 1 between the incident surface 151 and the semiconductor portion 11. The surface layer 12 is composed of multiple layers: a light-shielding film 121, an oxide film 122, and an electrode layer 123. The electrode layer 123 is provided in the portion of the semiconductor portion 11 on the incident surface 151 side. The electrode layer 123 is doped with a dopant that makes Si a different type of semiconductor from the components of the semiconductor portion 11. The component of the electrode layer 123 is p-type Si doped with a specific dopant such as boron, e.g., p+Si. The electrode layer 123 functions as an electrode. The electrode layer 123 is formed over most of the area along the incident surface 151, including the portion corresponding to the center of the incident surface 151 in a planar view. For example, the electrode layer 123 has a circular shape in a planar view. The electrode layer 123 is formed in all areas of the incident surface 151 that correspond to portions not covered by the collimator 22. There are areas along the periphery of the area along the incident surface 151 where the electrode layer 123 is not formed.

A ring-shaped guard ring electrode 161 is provided on the outside of the electrode layer 123. The guard ring electrode 161 is arranged in a position that surrounds the periphery of the electrode layer 123. The potential of the guard ring electrode 161 is a floating potential. Although a single guard ring electrode 161 is shown in FIG. 4, in reality, multiple ring-shaped guard ring electrodes 161 are provided. The guard ring electrode 161 prevents dielectric breakdown between the edge of the semiconductor portion 11 and the electrode layer 123. A ground electrode connected to a ground potential may be provided outside the guard ring electrode 161. If a ground electrode is provided, the guard ring electrode 161 prevents dielectric breakdown between the electrode layer 123 and the ground electrode.

The electrode layer 123 and the portion of the semiconductor portion 11 on the incident surface 151 side are covered with an oxide film 122. The oxide film 122 is composed of an oxide of Si. The electrode layer 123 is connected to the outside of the radiation detection element 1. For example, a metal electrode (not shown) that penetrates the oxide film 122 is connected to the electrode layer 123, and the guard ring electrode 161 is connected to the outside of the radiation detection element 1 via the metal electrode.

At least a portion of the oxide film 122 is covered with the light-shielding film 121. At least the portion of the oxide film 122 that is not overlapped by the collimator 22 in a planar view is covered with the light-shielding film 121. The light-shielding film 121 is made of a material with light-shielding properties. For example, the light-shielding film 121 is made of aluminum or carbon. The light-shielding film 121 may also be made of gold, beryllium, or magnesium. Alternatively, the light-shielding film 121 may be made of an alloy containing aluminum, carbon, gold, beryllium, or magnesium. The light-shielding film 121 effectively prevents light from entering the interior of the radiation detection element 1, preventing noise from being generated by light. For example, the surface of the light-shielding film 121 forms the incident surface 151. The light-shielding film 121 may be further covered with a protective film.

A signal output electrode 13, which outputs a signal when radiation is detected, is provided on the portion of the semiconductor portion 11 facing the electrode surface 152. The signal output electrode 13 is made of the same type of Si as the semiconductor portion 11. For example, the signal output electrode 13 is made of n+Si, which is Si doped with a specific dopant such as phosphorus. Furthermore, a plurality of curved electrodes 14, which form multiple rings in a planar view, are provided on the portion of the semiconductor portion 11 facing the electrode surface 152. The curved electrode 14 is made of a semiconductor of a different type from the semiconductor portion 11, and is made of p-type Si, which is Si doped with a specific dopant such as boron. For example, the curved electrode 14 is made of p+Si. The curved electrodes 14 are approximately concentric, with the signal output electrode 13 located approximately in the center of the curved electrodes 14. In other words, the curved electrodes 14 surround the signal output electrode 13, and the distances between the signal output electrode 13 and each curved electrode 14 are different.

Although four curved electrodes 14 are shown in Figure 4, more curved electrodes 14 are actually provided. The shape of the curved electrodes 14 may be a ring other than a circular ring, and the multiple curved electrodes 14 do not have to be concentric. The shape of the curved electrodes 14 may be a ring with a portion missing. The signal output electrode 13 may be located at a position other than the center of the multiple curved electrodes 14. The radiation detection element 1 may have a configuration having multiple sets of a signal output electrode 13, multiple curved electrodes 14, and electrode layer 123.

A ring-shaped guard ring electrode 162 is provided on the outside of the multiple curved electrodes 14, and a ring-shaped ground electrode 163 is provided on the outside of the guard ring electrode 162. The ground electrode 163 is connected to ground potential. The potential of the guard ring electrode 162 is floating potential. The guard ring electrode 162 prevents dielectric breakdown between the curved electrode 14 and the ground electrode 163. While a single guard ring electrode 162 is shown in FIG. 4, in reality, multiple guard ring electrodes 162 are provided in multiple ring shapes. Note that the ground electrode 163 may not be provided, and a ground electrode may be provided on the incident surface 151 side. When the ground electrode 163 is not provided, the guard ring electrode 162 prevents dielectric breakdown between the edge of the semiconductor portion 11 and the curved electrode 14. A ground electrode must be provided on at least one of the incident surface 151 or electrode surface 152 side.

Guard ring electrodes 161 and 162 are made of a different type of semiconductor than semiconductor portion 11, i.e., p-type Si. For example, the components of guard ring electrodes 161 and 162 are p+Si. Guard ring electrodes 161 and 162 have the same polarity. Note that the potential of guard ring electrodes 161 and 162 may be a fixed potential.

The portion of the semiconductor portion 11 facing the electrode surface 152 is covered with an oxide film 124. The oxide film 124 is composed of an oxide of silicon. A silicon nitride film may be provided instead of the oxide film 124. The oxide film 124 may be further covered with a protective film. The signal output electrode 13, the curved electrode 14, and the ground electrode 163 are connected to the outside of the radiation detection element 1. For example, metal electrodes (not shown) that penetrate the oxide film 124 are connected to the signal output electrode 13, the curved electrode 14, and the ground electrode 163, respectively. The signal output electrode 13, the curved electrode 14, and the ground electrode 163 are connected to the outside of the radiation detection element 1 via the metal electrodes.

The innermost curved electrode 14 and the outermost curved electrode 14 are connected to a voltage application unit 31. A voltage is applied from the voltage application unit 31 to the multiple curved electrodes 14 so that the innermost curved electrode 14 has the highest potential and the outermost curved electrode 14 has the lowest potential. The radiation detection element 1 is also configured so that a predetermined electrical resistance is generated between adjacent curved electrodes 14 that are at different distances from the signal output electrode 13. For example, by adjusting the components of the portion located between adjacent curved electrodes 14, an electrical resistance channel connecting the two curved electrodes 14 is formed. In other words, the multiple curved electrodes 14 are connected in a daisy chain via electrical resistance. When a voltage is applied, each curved electrode 14 has a potential that monotonically increases in order from the outer curved electrode 14 to the inner curved electrode 14. That is, the potential of the curved electrodes 14 increases sequentially from the curved electrodes 14 farthest from the signal output electrode 13 to the curved electrodes 14 closest to the signal output electrode 13. Note that the multiple curved electrodes 14 may include a pair of adjacent curved electrodes 14 with the same potential.

The potentials of the multiple curved electrodes 14 generate an electric field (potential gradient) within the semiconductor portion 11, where the potential increases gradually closer to the signal output electrode 13 and decreases gradually farther from the signal output electrode 13. The electrode layer 123 is also connected to the voltage application unit 31. A voltage is applied to the electrode layer 123 from the signal output electrode 13 so that the potential of the electrode layer 123 is equal to the potential between the innermost curved electrode 14 and the outermost curved electrode 14. In this way, an electric field is generated within the semiconductor portion 11, where the potential increases the closer to the signal output electrode 13.

Radiation is irradiated from the irradiation unit 35 onto the sample 52, and radiation such as fluorescent X-rays is generated in the sample 52, which then enters the radiation detector 2. The radiation mainly passes through the opening 251 and enters the interior of the radiation detector 2. Some of the radiation that enters the interior of the radiation detector 2 is blocked by the collimator 22. Radiation that is not blocked by the collimator 22 enters the radiation detection element 1 from the incident surface 151. The radiation that enters the radiation detection element 1 passes through the surface layer 12 and enters the semiconductor portion 11. The surface layer 12 is an object through which the radiation passes before entering the semiconductor portion 11, and the thickness of the surface layer 12 corresponds to the amount of material in the surface layer 12 through which the radiation passes.

Radiation incident on the semiconductor portion 11 is absorbed within the semiconductor portion 11, and an amount of charge corresponding to the energy of the absorbed radiation is generated within the semiconductor portion 11. The generated charges are electrons and holes. The generated charges move due to the electric field inside the semiconductor portion 11, and one type of charge concentrates and flows into the signal output electrode 13. In this embodiment, electrons generated by the incidence of radiation move and flow into the signal output electrode 13. The charge that flows into the signal output electrode 13 is output as a current signal.

The signal output electrode 13 is connected to the preamplifier 21. The signal output by the signal output electrode 13 is input to the preamplifier 21. The preamplifier 21 converts the current signal into a voltage signal. The preamplifier 21 outputs a signal with an intensity corresponding to the radiation energy. The preamplifier 21 is connected to the signal processing unit 32. When the preamplifier 21 outputs a signal, the radiation detector 2 outputs a signal with an intensity corresponding to the radiation energy. The signal processing unit 32 receives the signal output by the radiation detector 2 and detects the signal intensity, thereby detecting a signal value corresponding to the radiation energy detected by the radiation detector 2. The signal processing unit 32 counts the signals for each signal value and outputs data indicating the relationship between the signal value and the count number to the analysis device 4.

Figure 5 is a block diagram showing an example of the internal configuration of the analysis device 4. The analysis device 4 is a computer such as a personal computer. The analysis device 4 includes a calculation unit 41, a memory 42, a reading unit 43, a storage unit 44, and an operation unit 45. The analysis device 4 is also connected to the signal processing unit 32, the control unit 33, and the display unit 34. The calculation unit 41 is configured using, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or a multi-core CPU. The calculation unit 41 may also be configured using a quantum computer. The memory 42 stores temporary data generated during calculations. The memory 42 is, for example, a RAM (Random Access Memory). The reading unit 43 reads information from a recording medium 40 such as an optical disc or portable memory.

The storage unit 44 is non-volatile, and is, for example, a hard disk or non-volatile semiconductor memory. The operation unit 45 accepts input of information such as text by accepting operations from the user. The operation unit 45 is, for example, a touch panel, keyboard, or pointing device.

The calculation unit 41 causes the reading unit 43 to read the computer program 441 recorded on the recording medium 40, and stores the read computer program 441 in the memory unit 44. The calculation unit 41 executes the processing required for the analysis device 4 in accordance with the computer program 441. The computer program 441 may be downloaded from outside the analysis device 4. Alternatively, the computer program 441 may be pre-stored in the memory unit 44. In these cases, the analysis device 4 does not need to include the reading unit 43. The analysis device 4 may be composed of multiple computers. Alternatively, the control unit 33 and the analysis device 4 may be composed of the same computer.

The analysis device 4 receives data indicating the relationship between the signal value output by the signal processing unit 32 and the count number. Based on the data from the signal processing unit 32, the analysis device 4 generates a spectrum of the radiation incident on the semiconductor unit 11. Since the signal value corresponds to the radiation energy and the count number corresponds to the number of times the radiation is detected, the radiation spectrum can be obtained from the relationship between the signal value and the count number. The spectrum indicates the relationship between the radiation energy and intensity. The process of counting the signals output by the radiation detector 2 by signal value may be performed by the analysis device 4 instead of the signal processing unit 32. The radiation spectrum may be generated by the signal processing unit 32. The analysis device 4 stores spectral data representing the radiation spectrum in the memory unit 44.

Figure 6 is a graph showing an example of the spectrum of radiation incident on the semiconductor portion 11. The horizontal axis in the graph represents the radiation energy, and the vertical axis represents the radiation intensity. The radiation spectrum includes multiple peaks. More specifically, radiation having an energy corresponding to the components is generated from the sample 52, and the radiation spectrum includes peaks corresponding to the components of the sample 52. The radiation spectrum includes a system peak resulting from characteristic X-rays generated within the radiation detector 2. The position of the system peak is indicated by an arrow in Figure 6. The analysis device 4 executes an information processing method for correcting the radiation spectrum. More specifically, the analysis device 4 executes a process for correcting the radiation spectrum by subtracting the system peak from the generated radiation spectrum. The analysis device 4 corresponds to the information processing unit.

As described above, radiation from the sample 52 passes through the opening 251, penetrates the surface layer 12, and enters the semiconductor portion 11. Because the opening 251 is not blocked, it does not affect the radiation passing through it. Some of the radiation is absorbed by the surface layer 12 as it passes through it. This causes the radiation to attenuate. Furthermore, characteristic X-rays, such as fluorescent X-rays, are generated from the surface layer 12 that has absorbed the radiation. The characteristic X-rays enter the semiconductor portion 11 and are detected. In this way, the detected radiation contains characteristic X-rays from the surface layer 12, and the spectrum of the radiation is mixed with the spectrum of the characteristic X-rays. The spectrum of the characteristic X-rays from the surface layer 12 forms the system peak.

The memory unit 44 stores characteristic data 442, which records numerical values representing the radiation-related characteristics of the radiation detector 2. The numerical values recorded in the characteristic data 442 are used in the information processing executed by the analysis device 4. FIG. 7 is a conceptual diagram showing an example of the content of the characteristic data 442. The characteristic data 442 records absorption coefficients representing the radiation absorption characteristics of the light-shielding film 121, the oxide film 122, and the electrode layer 123. If the intensity of the radiation incident on an object is I ₀ , the intensity of the radiation that has passed through the object is I, the absorption coefficient of the object is μ, and the thickness of the object through which the radiation has passed is d, the following equation (1) holds:
I=I ₀ exp(-μd)...(1)

The absorption coefficient varies depending on the radiation energy. Figure 8 is a graph showing the relationship between the absorption coefficient and the radiation energy. The horizontal axis in the graph represents the radiation energy, and the vertical axis represents the absorption coefficient for radiation of each energy. Generally, the higher the energy of radiation, the easier it is for it to penetrate an object, and the absorption coefficient tends to decrease as the radiation energy increases. However, the absorption coefficient increases sharply at a specific energy called the absorption edge. The energy of the absorption edge is the energy that causes an electron transition in an object. When radiation with an energy higher than the absorption edge is absorbed by an object, atoms in the object are excited and characteristic X-rays with an energy lower than the absorption edge are emitted. The specific band in which radiation that generates characteristic X-rays is absorbed by an object is called the absorption band. The absorption band is a band that includes energies higher than the absorption edge. When radiation included in the absorption band is absorbed by an object, characteristic X-rays with energies lower than the absorption band are emitted from the object. In other words, the system peak caused by the characteristic X-rays from the object occurs in a band of energy lower than the absorption band.

The absorption coefficient varies depending on the components of the object. The characteristic data 442 records the absorption coefficients for each of the light-shielding film 121, oxide film 122, and electrode layer 123. The characteristic data 442 also records the absorption coefficient values for each radiation energy for each of the light-shielding film 121, oxide film 122, and electrode layer 123, as shown in FIG. 8. The characteristic data 442 records the absorption bands for each of the light-shielding film 121, oxide film 122, and electrode layer 123. The characteristic data 442 may also record the absorption edge. The characteristic data 442 may also record information other than the absorption coefficient as information representing the radiation absorption characteristics.

The characteristic data 442 records the characteristic X-ray generation characteristics of each of the light-shielding film 121, the oxide film 122, and the electrode layer 123. The characteristic X-ray generation characteristics indicate the energy of the characteristic X-rays generated when radiation included in the absorption band is absorbed by an object. The characteristic X-ray generation characteristics also consist of characteristic values that indicate the intensity of the characteristic X-rays generated when the intensity of the radiation absorbed is high. For example, the characteristic X-ray generation characteristics include the fluorescence yield or branching ratio.

Characteristic data 442 records the thickness of each of the light-shielding film 121, oxide film 122, and electrode layer 123. The thicker each of the light-shielding film 121, oxide film 122, and electrode layer 123 is, the greater the amount of material through which radiation passing through each layer passes. Therefore, the thickness of each layer corresponds to the amount of material through which radiation passes. The thickness of each layer affects the intensity of radiation absorbed by each layer. The thickness of each layer also affects the intensity of characteristic X-rays generated in each layer. The order of the light-shielding film 121, oxide film 122, and electrode layer 123 is also recorded. For example, the order from closest to the semiconductor portion 11 is recorded.

The characteristic data 442 records a correction coefficient for correcting the intensity of the system peak. The characteristic X-rays generated in the surface layer 12 include those that do not enter the semiconductor portion 11. For example, in the radiation detection element 1 shown in FIG. 4 , among the characteristic X-rays generated in the surface layer 12, those emitted toward the upper side of the figure, i.e., away from the semiconductor portion 11, do not enter the semiconductor portion 11. For example, if a component that reflects characteristic X-rays is disposed within the radiation detector 2, some of the characteristic X-rays emitted away from the semiconductor portion 11 may be reflected by this component and enter the semiconductor portion 11. In this way, the proportion of the characteristic X-rays generated by the light-shielding film 121 that enter the semiconductor portion 11 varies depending on the configuration of the radiation detector 2. Therefore, the intensity of the system peak also varies depending on the configuration of the radiation detector 2. The correction coefficient is a coefficient for correcting the intensity of the characteristic X-rays that enter the semiconductor portion 11 depending on the configuration of the radiation detector 2, and is a value specific to the radiation detector 2. The value of the correction coefficient is less than 1.

The various numerical values recorded in the characteristic data 442 are obtained and recorded through theoretical calculations or experiments. The calculation unit 41 reads out the numerical values recorded in the characteristic data 442 as necessary and performs the information processing described below using the read out numerical values. Note that some or all of the numerical values representing the radiation-related characteristics of the radiation detector 2 may be stored outside the analysis device 4, and the calculation unit 41 may acquire the numerical values stored outside the analysis device 4 and perform information processing. For example, the numerical values representing the radiation-related characteristics of the radiation detector 2 are stored in a database connected to the analysis device 4 via a communications network, and the characteristic data 442 records links for referencing each numerical value. The calculation unit 41 may use the link to acquire the numerical values required for information processing from the database.

The information processing performed by the analysis device 4 will be described below. Figure 9 is a flowchart showing a first example of the procedure for information processing to correct the radiation spectrum performed by the analysis device 4. In the first example, only the characteristic X-rays from the light-shielding film 121 are treated as the cause of the system peak. The characteristic X-rays generated from the oxide film 122 and electrode layer 123 are assumed to have low intensity and are not taken into consideration. Hereinafter, step will be abbreviated as S. The analysis device 4 performs the following processing by the calculation unit 41 performing information processing in accordance with the computer program 441.

The analysis device 4 calculates the spectrum of the radiation incident on the electrode layer 123 based on the spectrum of the radiation incident on the semiconductor portion 11 (S11). In S11, for example, the calculation unit 41 calculates I0 in equation ( ₁ ) by assuming that I is the intensity based on the generated spectrum of the radiation, _I0 is the intensity of the radiation incident on the electrode layer 123, μ is the absorption coefficient of the electrode layer 123, and d is the thickness of the electrode layer 123. The calculation unit 41 calculates _I0 for each energy to calculate the spectrum of the radiation incident on the electrode layer 123.

The analysis device 4 calculates the spectrum of the radiation incident on the oxide film 122 (S12). In S12, the calculation unit 41 calculates the spectrum of the radiation incident on the oxide film 122 based on the spectrum of the radiation incident on the electrode layer 123. For example, the calculation unit 41 calculates I0 in equation (1) by assuming that I is the intensity based on the spectrum of the radiation incident on the electrode layer 123, _I0 is the intensity of the radiation incident on the oxide film 122, μ is the absorption coefficient of the oxide film 122, and _d is the thickness of the oxide film 122. The calculation unit 41 calculates _I0 for each energy to calculate the spectrum of the radiation incident on the oxide film 122.

The analysis device 4 calculates the spectrum of the radiation incident on the light-shielding film 121 (S13). In S13, the calculation unit 41 calculates the spectrum of the radiation incident on the light-shielding film 121 based on the spectrum of the radiation incident on the oxide film 122. For example, the calculation unit 41 calculates I0 in equation (1) by defining I as the intensity based on the spectrum of the radiation incident on the oxide film 122, _I0 as the intensity of the radiation incident on the light-shielding film 121, μ as the absorption coefficient of the light-shielding film 121, and d as the thickness of the light-shielding film 121. The calculation unit 41 calculates _I0 for each energy to calculate the spectrum of the radiation incident on _the light-shielding film 121. The calculation of the spectrum of the radiation incident on each layer of the surface layer 12 in S11 to S13 is performed for each layer in order from the layer closest to the semiconductor portion 11.

When irradiated with radiation, the light-shielding film 121 generates characteristic X-rays. Therefore, the radiation incident on the oxide film 122 includes characteristic X-rays generated by the light-shielding film 121. The radiation spectrum calculated in S13 is calculated based on the spectrum of radiation, including characteristic X-rays, incident on the oxide film 122. Therefore, it differs from the spectrum of radiation actually incident on the light-shielding film 121 and includes peaks due to the characteristic X-rays. As described above, when radiation with energy higher than the absorption edge is absorbed by an object, characteristic X-rays with energy lower than the absorption edge are generated. Therefore, the energy of the characteristic X-rays is lower than the absorption band in which the radiation that generates the characteristic X-rays is absorbed. The peaks due to the characteristic X-rays are not included in the absorption band. Therefore, the spectrum in the absorption band of the radiation spectrum calculated in S13 corresponds to the spectrum of radiation actually incident on the light-shielding film 121. In S13, the analyzer 4 may calculate only the spectrum in the absorption band.

The analysis device 4 calculates the spectrum of the characteristic X-rays generated by the light-shielding film 121 (S14). In S14, the calculation unit 41 calculates the spectrum of the characteristic X-rays generated by the light-shielding film 121 based on the spectrum in the absorption band of the radiation incident on the light-shielding film 121, the generation characteristics of the characteristic X-rays in the light-shielding film 121, and the thickness of the light-shielding film 121. The generation characteristics of the characteristic X-rays indicate the energy of the characteristic X-rays and the intensity of the characteristic X-rays corresponding to the intensity in the absorption band of the radiation incident on the light-shielding film 121. Furthermore, the thicker the light-shielding film 121, the greater the amount of material in the light-shielding film 121 through which radiation passes, and the greater the intensity of the generated characteristic X-rays. The thickness of the light-shielding film 121 corresponds to the amount of material in the light-shielding film 121 through which radiation passes. The calculation unit 41 identifies the energy of the characteristic X-rays and calculates the intensity of the characteristic X-rays to calculate the spectrum of the characteristic X-rays.

The analyzer 4 calculates the spectrum of the characteristic X-rays incident on the semiconductor portion 11 (S15). In S15, the calculation unit 41 calculates the spectrum of the characteristic X-rays incident on the semiconductor portion 11 based on the spectrum of the characteristic X-rays generated in the light-shielding film 121, the absorption coefficients and thicknesses of the oxide film 122 and the electrode layer 123, and the correction coefficient. For example, the calculation unit 41 defines the intensity of the characteristic X-rays generated in the light-shielding film 121 as I ₀ and the intensity of the characteristic X-rays that have passed through the oxide film 122 and entered the electrode layer 123 as I, and calculates the intensity of the characteristic X-rays that have passed through the electrode layer 123 and entered the semiconductor portion 11 using the absorption coefficient and thickness of the oxide film 122. The calculation unit 41 also defines the intensity of the characteristic X-rays that have passed through the electrode layer 123 as I ₀ and the intensity of the characteristic X-rays that have passed through the electrode layer 123 and entered the semiconductor portion 11 as I, and calculates the intensity of the characteristic X-rays that have entered the semiconductor portion 11 using the absorption coefficient and thickness of the electrode layer 123. The thicker the oxide film 122 and the electrode layer 123, the greater the amount of material in the oxide film 122 and the electrode layer 123 through which the characteristic X-rays pass, and the lower the intensity of the characteristic X-rays incident on the semiconductor portion 11. The thickness of the oxide film 122 and the electrode layer 123 corresponds to the amount of material in the oxide film 122 and the electrode layer 123 through which the characteristic X-rays pass.

Furthermore, the calculation unit 41 corrects the intensity of the characteristic X-rays incident on the semiconductor portion 11 by multiplying the calculated intensity of the characteristic X-rays by a correction coefficient. By using the correction coefficient, the intensity of the characteristic X-rays incident on the semiconductor portion 11 is corrected according to the configuration of the radiation detector 2. By using the correction coefficient, the intensity of the characteristic X-rays incident on the semiconductor portion 11 can be accurately calculated. Furthermore, by using the correction coefficient, it is possible to separate the absorption of the characteristic X-rays in the oxide film 122 and electrode layer 123 from the influence on the characteristic X-rays by the configuration of the radiation detector 2. For example, even in radiation detection devices 10 that have the same radiation detection element 1 but different parts of the radiation detector 2 other than the radiation detection element 1, the intensity of the characteristic X-rays incident on the semiconductor portion 11 can be calculated using the same transmission ratio and a correction coefficient according to the configuration of the radiation detector 2.

By correcting the intensities of the characteristic X-rays corresponding to each energy, the calculation unit 41 calculates the spectrum of the characteristic X-rays incident on the semiconductor unit 11. The spectrum of the characteristic X-rays incident on the semiconductor unit 11 corresponds to the system peak caused by the characteristic X-rays. Therefore, the analysis device 4 calculates the system peak by calculating the spectrum of the characteristic X-rays incident on the semiconductor unit 11. Figure 10 is a graph showing an example of the spectrum of the characteristic X-rays incident on the semiconductor unit 11. The horizontal axis in the graph represents the energy of the characteristic X-rays, and the vertical axis represents the intensity of the characteristic X-rays. The spectrum of the characteristic X-rays shown in Figure 10 corresponds to the system peak caused by the characteristic X-rays.

In S14, the analysis device 4 may perform a process to correct the intensity of the characteristic X-rays generated by the light-shielding film 121 by multiplying the intensity of the characteristic X-rays by a correction coefficient. In S15, the analysis device 4 may use the correction coefficient to correct the intensity of the characteristic X-rays generated by the light-shielding film 121 or the intensity of the characteristic X-rays incident on the electrode layer 123. Alternatively, in S15, the analysis device 4 may calculate the intensity of the characteristic X-rays incident on the semiconductor portion 11 by a calculation that does not use the correction coefficient. For example, the generation characteristics of the characteristic X-rays may be set in advance to values that incorporate the influence of the configuration of the radiation detector 2, and the calculation unit 41 may calculate the intensity of the characteristic X-rays incident on the semiconductor portion 11 by a calculation using these generation characteristics.

The analysis device 4 corrects the spectrum of the radiation incident on the semiconductor unit 11 using the calculated system peak (S16). In S16, the calculation unit 41 corrects the spectrum of the radiation incident on the semiconductor unit 11 by subtracting the system peak from the spectrum of the radiation incident on the semiconductor unit 11. The calculation unit 41 stores data representing the corrected spectrum of the radiation in the memory unit 44.

Figure 11 is a graph showing the corrected radiation spectrum. The horizontal axis in the graph represents radiation energy, and the vertical axis represents radiation intensity. Compared to the radiation spectrum before correction as shown in Figure 6, the system peak corresponding to the characteristic X-ray spectrum as shown in Figure 10 has been reduced. Because the system peak has been reduced, the corrected spectrum corresponds to the spectrum of radiation incident on the radiation detector 2.

The analysis device 4 displays the corrected radiation spectrum (S17). In S17, the calculation unit 41 displays an image including the corrected radiation spectrum on the display unit 34. The user can confirm the radiation spectrum with the reduced system peak. The analysis device 4 may also display the spectrum before correction. For example, the calculation unit 41 may display an image showing the spectrum before correction and the corrected spectrum side by side on the display unit 34. For example, the calculation unit 41 may perform a process of alternately switching between displaying the spectrum before correction and the corrected spectrum in accordance with instructions received by the user operating the operation unit 45. After S17 is completed, the analysis device 4 ends the information processing for correcting the radiation spectrum.

Figure 12 is a flowchart showing a second example of the information processing procedure for correcting the radiation spectrum executed by the analysis device 4. In the second example, characteristic X-rays from the light-shielding film 121 and characteristic X-rays from the oxide film 122 are treated as causes of the system peak. The calculation unit 41 executes information processing in accordance with the computer program 441, causing the analysis device 4 to perform the following processing. The analysis device 4 calculates the spectrum of radiation incident on the electrode layer 123 based on the spectrum of radiation incident on the semiconductor portion 11 (S201). In S201, the calculation unit 41 performs processing similar to S11. The analysis device 4 calculates the spectrum of radiation incident on the oxide film 122 (S202). In S202, the calculation unit 41 performs processing similar to S12. In S202, the analysis device 4 may calculate only the spectrum in the absorption band.

The analysis device 4 calculates the spectrum of the characteristic X-rays generated in the oxide film 122 (S203). In S203, the calculation unit 41 calculates the spectrum of the characteristic X-rays generated in the oxide film 122 based on the spectrum in the absorption band of the radiation incident on the oxide film 122, the generation characteristics of the characteristic X-rays in the oxide film 122, and the thickness of the oxide film 122. The calculation unit 41 calculates the spectrum of the characteristic X-rays by identifying the energy of the characteristic X-rays and calculating the intensity of the characteristic X-rays.

The analyzer 4 calculates the spectrum of the characteristic X-rays generated in the oxide film 122 and incident on the semiconductor portion 11 (S204). In S204, the calculation unit 41 calculates the spectrum of the characteristic X-rays incident on the semiconductor portion 11 based on the spectrum of the characteristic X-rays generated in the oxide film 122, the absorption coefficient and thickness of the electrode layer 123, and the correction coefficient. For example, the calculation unit 41 defines the intensity of the characteristic X-rays generated in the oxide film 122 as I ₀ and the intensity of the characteristic X-rays that have passed through the electrode layer 123 and incident on the semiconductor portion 11 as I, and calculates the intensity of the characteristic X-rays incident on the semiconductor portion 11 using the absorption coefficient and thickness of the electrode layer 123. Furthermore, the calculation unit 41 corrects the intensity of the characteristic X-rays incident on the semiconductor portion 11 by multiplying the calculated intensity of the characteristic X-rays by the correction coefficient. By correcting the intensities of the characteristic X-rays corresponding to each energy, the calculation unit 41 calculates the spectrum of the characteristic X-rays generated in the oxide film 122 and incident on the semiconductor portion 11.

The analysis device 4 calculates the spectrum of the radiation incident on the light-shielding film 121 (S205). In S205, the calculation unit 41 performs processing similar to S13. In S205, the analysis device 4 may calculate only the spectrum in the absorption band. The analysis device 4 calculates the spectrum of the characteristic X-rays generated in the light-shielding film 121 (S206). In S206, the calculation unit 41 performs processing similar to S14. The analysis device 4 calculates the spectrum of the characteristic X-rays generated in the light-shielding film 121 and incident on the semiconductor portion 11 (S207). In S207, the calculation unit 41 performs processing similar to S13.

The analysis device 4 calculates the system peak (S208). In S208, the calculation unit 41 calculates the system peak by adding together the spectrum of the characteristic X-rays generated in the oxide film 122 and incident on the semiconductor portion 11 and the spectrum of the characteristic X-rays generated in the light-shielding film 121 and incident on the semiconductor portion 11.

The analysis device 4 corrects the spectrum of the radiation incident on the semiconductor portion 11 using the calculated system peak (S209). In S209, the calculation unit 41 corrects the spectrum of the radiation incident on the semiconductor portion 11 by subtracting the system peak from the spectrum of the radiation incident on the semiconductor portion 11. In S208 and S209, the analysis device 4 may correct the spectrum without adding the spectrum of the characteristic X-rays from the oxide film 122 and the spectrum of the characteristic X-rays from the light-shielding film 121 together. In this process, the calculation unit 41 corrects the spectrum of the radiation incident on the semiconductor portion 11 by subtracting the spectrum of the characteristic X-rays from the oxide film 122 and the spectrum of the characteristic X-rays from the light-shielding film 121 from the spectrum of the radiation incident on the semiconductor portion 11. The calculation unit 41 stores data representing the corrected radiation spectrum in the memory unit 44.

The analysis device 4 displays the corrected radiation spectrum (S210). In S210, the calculation unit 41 performs processing similar to S17. After S210 is completed, the analysis device 4 ends the information processing for correcting the radiation spectrum.

The processes of S11 to S17 or S201 to S210 are executed as needed. For example, the analysis device 4 executes the processes of S11 to S17 or S201 to S210 each time a radiation spectrum is generated. The analysis device 4 may also execute the processes of S11 to S17 or S201 to S210 when a correction instruction is received by the user operating the operation unit 45. The analysis device 4 may perform information processing to correct the radiation spectrum, treating characteristic X-rays from the light-shielding film 121, oxide film 122, and electrode layer 123 as causes of the system peak. The analysis device 4 may further perform information processing based on the corrected radiation spectrum. For example, the analysis device 4 may perform qualitative or quantitative analysis of elements contained in the sample 52 based on the corrected radiation spectrum.

As described above in detail, in this embodiment, the radiation detector 2 detects radiation emitted from the sample 52, and the analysis device 4 generates and corrects the radiation spectrum. More specifically, the analysis device 4 calculates the intensity of the radiation incident on the semiconductor portion 11, calculates a system peak according to the components and thickness of the surface layer 12, and subtracts the system peak from the radiation spectrum. By subtracting the system peak from the radiation spectrum, a spectrum with a reduced system peak is obtained. By calculating the system peak according to the components and thickness of the surface layer 12, a system peak of appropriate intensity is obtained. Therefore, the system peak can be appropriately reduced from the radiation spectrum.

By reducing the system peak, the spectrum of the radiation incident on the radiation detector 2 is obtained. The user can check the spectrum of the radiation incident on the radiation detector 2. Based on the spectrum with the reduced system peak, it becomes possible to perform analysis with higher accuracy than before. For example, the analysis device 4 can perform qualitative or quantitative analysis of elements contained in the sample 52 with high accuracy.

In this embodiment, an example has been shown in which the thickness of each layer is used as a value corresponding to the amount of material through which radiation or characteristic X-rays pass through each of the light-shielding film 121, oxide film 122, and electrode layer 123. When performing the processes of S11 to S17 or S201 to S210, the radiation detection device 10 may use a value other than thickness as a value corresponding to the amount of material through which radiation or characteristic X-rays pass. For example, the radiation detection device 10 may perform the processes of S11 to S17 or S201 to S210 using the amount of material along the path of the radiation or characteristic X-rays in each layer, or the density or mass fraction of each layer, as a value corresponding to the amount of material through which radiation or characteristic X-rays pass.

In this embodiment, the housing 25 has an opening 251 that is not blocked by a window material, and radiation that passes through the opening 251 is detected. Because the detected radiation does not need to pass through a window material, the radiation detection device 10 can detect radiation that is too low in energy to pass through a window material. On the other hand, light is more likely to pass through the opening 251 and enter the interior of the radiation detector 2. The light-shielding film 121 is required to prevent light from entering the interior of the radiation detection element 1 and generating noise, and a system peak occurs due to the light-shielding film 121. In this embodiment, it is possible to prevent the generation of noise due to light, while obtaining a radiation spectrum with a reduced system peak through information processing.

While the present embodiment illustrates a configuration in which the surface layer 12 is composed of the light-shielding film 121, the oxide film 122, and the electrode layer 123, the surface layer 12 may also be composed of more layers. The radiation detector 2 may not have an opening 251, but may include a window with a window material, and detect radiation that has passed through the window. The radiation detection device 10 may also be configured to treat objects other than the surface layer 12 as objects through which radiation passes before entering the semiconductor portion 11. That is, the radiation detection device 10 may also be configured to subtract from the radiation spectrum system peaks resulting from characteristic X-rays emitted from objects other than the surface layer 12. For example, the radiation detection device 10 subtracts from the radiation spectrum system peaks resulting from characteristic X-rays emitted from the window or collimator 22 included in the radiation detector 2. In this configuration, the analysis device 4 can subtract from the radiation spectrum system peaks resulting from characteristic X-rays from the window or collimator 22 by performing processing similar to that for the surface layer 12.

In this embodiment, the semiconductor constituting the radiation detection element 1 is Si, but the radiation detection element 1 may be made of a semiconductor other than Si. In this embodiment, the semiconductor portion 11 is made of an n-type semiconductor, and the electrode layer 123 and the curved electrode 14 are made of a p-type semiconductor, but the radiation detection element 1 may be made of a p-type semiconductor, and the electrode layer 123 and the curved electrode 14 are made of an n-type semiconductor. In this embodiment, the radiation detection element 1 is a silicon drift type radiation detection element, but the radiation detection element 1 may be an element other than a silicon drift type radiation detection element as long as it is made of a semiconductor. Therefore, the radiation detector 2 may be a radiation detector other than an SDD.

In this embodiment, the radiation detector 2 is shown to include a collimator 22, but the radiation detector 2 may not include a collimator 22. In this embodiment, the radiation detection element 1 is shown to be housed in a housing 25, but the radiation detector 2 may not include a housing 25. In this embodiment, the radiation detection device 10 is shown to include an irradiation unit 35 and a sample stage 51, but the radiation detection device 10 may not include an irradiation unit 35 or a sample stage 51. In this embodiment, the horizontal axis of the radiation spectrum is energy, but the radiation detection device 10 may also be configured to handle spectra in which the horizontal axis represents a value other than energy, such as wavelength or wave number.

The present invention is not limited to the content of the above-described embodiment, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means that are appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

The matters described in each embodiment can be combined with each other. Furthermore, the independent claims and dependent claims described in the claims can be combined with each other in any and all combinations, regardless of the citation format. Furthermore, although the claims use a format in which a claim cites two or more other claims (multiple claim format), this is not limited to this. A multiple claim citing at least one other multiple claim (multi-multi claim) can also be used.

REFERENCE SIGNS LIST 10 Radiation detection device 1 Radiation detection element 11 Semiconductor part 12 Surface layer 121 Light-shielding film 122 Oxide film 123 Electrode layer 2 Radiation detector 25 Housing 251 Opening 34 Display part 35 Irradiation part 4 Analysis device 40 Recording medium 441 Computer program 52 Sample

Claims (8)

A radiation detection device including a radiation detection element having a semiconductor portion and an information processing unit,
the radiation detection element further includes a surface layer located between an incident surface onto which radiation is incident and the semiconductor portion,
The information processing unit
calculating a spectrum of radiation incident on the surface layer in a specific band in which radiation that generates characteristic X-rays is absorbed by the surface layer based on the spectrum of radiation incident on the semiconductor portion, the radiation absorption characteristics of the surface layer depending on the components of the surface layer, and the thickness of the surface layer ;
calculating a spectrum of the characteristic X-rays generated from the surface layer based on the calculated spectrum, the generation characteristics of the characteristic X-rays in the surface layer according to the components of the surface layer , and the amount of material in the surface layer through which radiation penetrates;
calculating a system peak by calculating a spectrum of the characteristic X-rays incident on the semiconductor portion based on the spectrum of the characteristic X-rays generated from the surface layer ;
a radiation detection device, characterized in that the calculated system peak is subtracted from the spectrum of the radiation incident on the semiconductor portion. the surface layer is composed of a plurality of layers,
The information processing unit
calculating a spectrum of radiation incident on each layer based on the order of the plurality of layers, the radiation absorption characteristics of each layer according to the components of each layer, and the amount of material in each layer through which the radiation passes;
calculating a spectrum of characteristic X-rays generated from each layer based on the spectrum of radiation incident on each layer, the generation characteristics of characteristic X-rays in each layer according to the components of each layer, and the amount of material through which radiation passes in each layer;
2. The radiation detection device according to claim 1, wherein the spectrum of characteristic X-rays from each layer incident on the semiconductor portion is calculated based on the spectrum of characteristic X-rays generated from each layer, the order of the plurality of layers, the radiation absorption characteristics of each layer depending on the components of each layer, and the amount of material in each layer through which characteristic X-rays from other layers pass. Further comprising a housing that accommodates the radiation detection element,
the housing has an unobstructed opening;
the radiation detection element is disposed with the incident surface facing the opening,
The radiation detection device according to claim 1 or 2 , wherein the surface layer includes a light-shielding film. 4. The radiation detection device according to claim 3 , wherein the light-shielding film is made of aluminum, carbon, gold, beryllium, magnesium, or an alloy thereof. Further comprising a radiation detector including the radiation detection element,
The information processing unit
3. The radiation detection device according to claim 1 , wherein a spectrum of the characteristic X-rays incident on the semiconductor portion is calculated using a correction coefficient specific to the radiation detector. an irradiation unit that irradiates radiation onto the sample;
The radiation detection device according to claim 1 or 2, further comprising: a display unit that displays the spectrum of the radiation after the system peak has been subtracted. calculating a spectrum of radiation incident on the surface layer in a specific band in which radiation that generates characteristic X-rays is absorbed by the surface layer based on the spectrum of radiation incident on the semiconductor part of the radiation detection element , the radiation absorption characteristics of the surface layer that are in accordance with the components of the surface layer that exists between the incident surface of the radiation detection element on which the radiation is incident and the semiconductor part , and the thickness of the surface layer ;
calculating a spectrum of the characteristic X-rays generated from the surface layer based on the calculated spectrum, the generation characteristics of the characteristic X-rays in the surface layer according to the components of the surface layer , and the amount of material in the surface layer through which radiation penetrates;
calculating a system peak by calculating a spectrum of the characteristic X-rays incident on the semiconductor portion based on the spectrum of the characteristic X-rays generated from the surface layer ;
an information processing method comprising: subtracting the calculated system peak from the spectrum of radiation incident on the semiconductor portion. calculating a spectrum of radiation incident on the surface layer in a specific band in which radiation that generates characteristic X-rays is absorbed by the surface layer based on the spectrum of radiation incident on the semiconductor part of the radiation detection element , the radiation absorption characteristics of the surface layer that are in accordance with the components of the surface layer that exists between the incident surface of the radiation detection element on which the radiation is incident and the semiconductor part , and the thickness of the surface layer ;
calculating a spectrum of the characteristic X-rays generated from the surface layer based on the calculated spectrum, the generation characteristics of the characteristic X-rays in the surface layer according to the components of the surface layer , and the amount of material in the surface layer through which radiation penetrates;
calculating a system peak by calculating a spectrum of the characteristic X-rays incident on the semiconductor portion based on the spectrum of the characteristic X-rays generated from the surface layer ;
A computer program causing a computer to execute a process of subtracting the calculated system peak from the spectrum of radiation incident on the semiconductor portion.