Radiation detection device and radiation detector

Abstract

Provided are a radiation detection device and a radiation detector that keep photoelectrons and illumination light from entering a radiation detection element therein.　This radiation detection device comprises an illumination unit that illuminates a sample, an irradiation unit that irradiates the sample with an X-ray, and a radiation detection element that detects an X-ray generated from the sample. The radiation detection device also comprises a magnetic field generation unit that generates a magnetic field in a portion of a space from the sample to the radiation detection element and a block that holds the magnetic field generation unit. The block is disposed in a position that blocks light from the illumination unit to the radiation detection element.

Description

Radiation detection device and radiation detector

[0001] The present invention relates to a radiation detection apparatus and a radiation detector for detecting fluorescent X-rays.

[0002] X-ray fluorescence analysis is a technique in which a sample is irradiated with X-rays, fluorescent X-rays emitted from the sample are detected, and the sample is analyzed from the spectrum of the fluorescent X-rays. The radiation detection element for detecting the fluorescent X-rays is, for example, an element using a semiconductor. In addition to fluorescent X-rays, photoelectrons are generated from the sample irradiated with X-rays. If photoelectrons enter the radiation detection element, the sensitivity of the fluorescent X-ray detection deteriorates. Therefore, measures against photoelectrons are required. Patent Document 1 discloses a technology for preventing secondary electrons from entering a radiation detection element for detecting X-rays in an electron microscope.

[0003] JP 2019-33080 A

[0004] In X-ray fluorescence analysis, a sample is illuminated and observed. When the illumination light for illuminating the sample is incident on a radiation detection element, a current is generated in the radiation detection element, which may cause a malfunction in a radiation detection device equipped with the radiation detection element.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a radiation detection device and a radiation detector that suppress the incidence of photoelectrons and illumination light on the radiation detection element.

[0006] A radiation detection device according to one aspect of the present invention includes an illumination unit that illuminates a sample, an irradiation unit that irradiates the sample with X-rays, and a radiation detection element that detects X-rays generated from the sample, and further includes a magnetic field generation unit that generates a magnetic field in a part of a space from the sample to the radiation detection element, and a block that holds the magnetic field generation unit, the block being positioned to block light from the illumination unit to the radiation detection element.

[0007] In one aspect of the present invention, a radiation detection device that detects fluorescent X-rays includes a magnetic field generating unit that generates a magnetic field in a portion of the space from a sample to a radiation detection element. The magnetic field bends the movement direction of photoelectrons generated from the sample, making it difficult for the photoelectrons to enter the radiation detection element. Therefore, the photoelectrons are prevented from entering the radiation detection element. The radiation detection device also includes a block that holds the magnetic field generating unit. The block blocks light from the illumination unit to the radiation detection element, making it difficult for the light to enter the radiation detection element. Therefore, the illumination light that illuminates the sample is prevented from entering the radiation detection element.

[0008] In the radiation detection device according to one aspect of the present invention, the magnetic field generating unit and the block are subjected to anti-reflection processing.

[0009] In one aspect of the present invention, the block and the magnetic field generating unit are subjected to an anti-reflection treatment, so that light is less likely to be reflected by the block and the magnetic field generating unit and less likely to reach the radiation detection element, thereby further suppressing light from entering the radiation detection element.

[0010] In a radiation detection device according to one aspect of the present invention, the magnetic field generating unit includes a magnet, and the magnet is coated with a substance made of an element having an atomic number smaller than that of the element contained in the magnet.

[0011] In one aspect of the present invention, the magnetic field generating unit includes a magnet, and the magnet is coated with a material having an atomic number smaller than that of the material constituting the magnet. X-rays generated from the magnet due to incidence of X-rays or collision of photoelectrons are absorbed by the material coating the magnet and are less likely to enter the radiation detection element. Fluorescent X-rays generated from the material coating the magnet have lower energy and intensity. This reduces the system peak caused by fluorescent X-rays from the magnet.

[0012] In one form of the radiation detection device of the present invention, the magnetic field generating unit includes a plurality of magnets facing each other across a portion of the space from the sample to the radiation detection element, and the spacing between the plurality of magnets varies along the direction from the sample to the radiation detection element, becoming wider as the magnets get closer to the radiation detection element.

[0013] In one aspect of the present invention, the magnetic field generating unit includes a plurality of magnets facing each other, and the intervals between the magnets increase from the sample toward the radiation detection element. Fluorescent X-rays generated from the sample increase in width as they approach the radiation detection element. By increasing the intervals between the magnets as they approach the radiation detection element, the probability that the fluorescent X-rays will be incident on the radiation detection element without being incident on the magnets increases, thereby increasing the probability that the fluorescent X-rays will be detected.

[0014] In one form of the radiation detection device of the present invention, the block has a space inside, the magnetic field generating unit is arranged inside the block, and the material of the block is a ferromagnetic material.

[0015] In one embodiment of the present invention, the magnetic field generating unit is disposed inside a block, and the block is made of a magnetic material. The magnetic field generated by the magnetic field generating unit is shielded by the block. Since the magnetic field does not leak outside the block, the magnetic field does not adversely affect the outside of the block.

[0016] In one aspect of the present invention, the radiation detection device is characterized in that a straight line path from the sample to the radiation detection element is not blocked.

[0017] In one aspect of the present invention, the linear path from the sample to the radiation detection element is not blocked by an object such as a window having a window material. The fluorescent X-rays are incident on the radiation detection element and detected without passing through the window material. The radiation detection device can detect radiation that cannot pass through a window material due to its low energy.

[0018] A radiation detection device according to one aspect of the present invention is characterized in that it further includes a spectrum generation unit that generates a spectrum of radiation detected using the radiation detection element, and a display unit that displays the spectrum generated by the spectrum generation unit.

[0019] In one aspect of the present invention, a spectrum of fluorescent X-rays emitted from a sample is generated and the generated spectrum is displayed on a display unit, allowing a user to check the spectrum of fluorescent X-rays emitted from the sample.

[0020] A radiation detector according to one aspect of the present invention is a radiation detector for detecting fluorescent X-rays, comprising: a block having a space therein; an entrance formed in the block through which the fluorescent X-rays are incident; a radiation detection element facing the entrance; and a magnetic field generation unit disposed inside the block and generating a magnetic field in a space from the entrance to the radiation detection element, wherein the entrance is not blocked and a straight line path from the entrance to the radiation detection element is not blocked.

[0021] In one aspect of the present invention, a radiation detector that detects fluorescent X-rays includes a block and a magnetic field generator that generates a magnetic field in a part of the space from the entrance to the radiation detection element. The magnetic field bends the direction of movement of photoelectrons that enter the radiation detector from the entrance, thereby preventing the photoelectrons from entering the radiation detection element. The block also blocks light from outside the radiation detector, making it difficult for the light to enter the radiation detection element. This prevents illumination light that illuminates a sample from entering the radiation detection element.

[0022] In the present invention, the incidence of photoelectrons and illumination light on the radiation detection element is suppressed, thereby suppressing deterioration in radiation detection sensitivity and suppressing malfunctions of the radiation detection device, thereby achieving excellent effects.

[0023] It is a block diagram showing an example of the functional configuration of a radiation detection device.It is a schematic cross-sectional view showing an example of the internal configuration of a radiation detector.It is a schematic cross-sectional view showing a radiation detection element and a collimator.

[0024] The present invention will be described in detail below with reference to the drawings illustrating 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 analyzer. It includes a sample stage 61 on which a sample 6 is placed, an irradiation unit 41 that irradiates X-rays onto the sample 6, an X-ray optical element 42 that focuses the X-rays, and a radiation detector 2. The sample 6 may be held by a method other than placing it on the stage. The irradiation unit 41 is, for example, an X-ray tube. The X-ray optical element 42 is, for example, a monocapillary lens using an X-ray guide that internally reflects and guides incident X-rays, or a polycapillary lens using multiple X-ray guides. The irradiation unit 41 emits X-rays, and the X-ray optical element 42 receives the X-rays emitted by the irradiation unit 41, converges the X-rays, and irradiates the focused X-rays onto the sample 6 placed on the sample stage 61. Fluorescent X-rays are generated in the sample 6 irradiated with X-rays, and the radiation detector 2 detects the fluorescent X-rays generated from the sample 6. In the figure, X-rays and fluorescent X-rays are indicated by arrows. Note that the radiation detection device 10 may be configured to hold the sample 6 by a method other than placing it on the sample stage 61.

[0025] The radiation detection device 10 includes an illumination unit 51 that illuminates the sample 6, a mirror 44, an imaging unit 52, and a switching stage 43 that switches the positions of the X-ray optical element 42 and the mirror 44. The illumination unit 51 has a light source such as an LED (light-emitting diode) and can be turned on and off. When the light source is turned on, illumination light for illuminating the sample 6 is generated. The illumination unit 51 illuminates the sample 6 placed on a sample stage 61. The imaging unit 52 images the sample 6 illuminated by the illumination unit 51. For example, the imaging unit 52 includes an optical system and an image sensor.

[0026] The switching stage 43 has an X-ray optical element 42 and a mirror 44 attached thereto, and can change the positions of the X-ray optical element 42 and the mirror 44 by moving it. A driver 32 that moves the switching stage 43 is connected to the switching stage 43. The driver 32 is configured using, for example, a motor. The operation of the driver 32 moves the switching stage 43, and the positions of the X-ray optical element 42 and the mirror 44 are changed. As shown in FIG. 1 , the switching stage 43 can position the X-ray optical element 42 at an irradiation position. The irradiation position is a position where X-rays from the irradiation unit 41 are incident on the X-ray optical element 42 and where X-rays emitted from the X-ray optical element 42 are irradiated onto the sample 6.

[0027] The switching stage 43 can change the positions of the X-ray optical element 42 and the mirror 44, and position the mirror 44 at the imaging position. The imaging position is a position where the optical axis of the mirror 44 when in the imaging position and the optical axis of the X-ray optical element 42 when in the irradiation position are approximately coaxial. When in the imaging position, the mirror 44 is located on the irradiation axis of the X-rays. Light from the illumination unit 51 is reflected by the sample 6. The mirror 44 in the imaging position reflects light from the sample 6 and makes it incident on the imaging unit 52. The imaging unit 52 uses the incident light to image the sample 6.

[0028] The radiation detector 2 includes a radiation detection element 1 and a preamplifier 21. A portion of the preamplifier 21 may be included inside the radiation detector 2, with the other portion being located outside the radiation detector 2. A signal processing unit 34 and a voltage application unit 33 that applies a voltage required for radiation detection to the radiation detection element 1 are connected to the radiation detector 2. An analysis unit 35 is connected to the signal processing unit 34. The analysis unit 35 is configured using a computer. A display unit 36 ​​such as a liquid crystal display or an EL display (Electroluminescent Display) is connected to the analysis unit 35.

[0029] The drive unit 32, the voltage application unit 33, the signal processing unit 34, the analysis unit 35, the display unit 36, the irradiation unit 41, the illumination unit 51, and the imaging unit 52 are connected to the control unit 31. The control unit 31 controls the operations of the drive unit 32, the voltage application unit 33, the signal processing unit 34, the analysis unit 35, the display unit 36, the irradiation unit 41, the illumination unit 51, and the imaging unit 52. The control unit 31 is configured using a computer including a calculation unit that executes calculations to control each unit. The control unit 31 may be configured to accept operations from a user and control each unit of the radiation detection device 10 in accordance with the accepted operation. The control unit 31 and the analysis unit 35 may be configured integrally.

[0030] The control unit 31 controls the drive unit 32 to move the switching stage 43 and position the mirror 44 at the imaging position. With the mirror 44 at the imaging position, the control unit 31 turns on the illumination unit 51. The sample 6 is illuminated with light from the illumination unit 51, and the imaging unit 52 images the sample 6. The imaging unit 52 generates an image of the sample 6 and transmits it to the control unit 31. The control unit 31 displays the image on the display unit 36. The user observes the sample 6 by visually viewing the image. The control unit 31 also controls the drive unit 32 to move the switching stage 43 and position the X-ray optical element 42 at the irradiation position. With the X-ray optical element 42 at the irradiation position, the control unit 31 causes the irradiation unit 41 to generate X-rays. The X-rays from the irradiation unit 41 pass through the X-ray optical element 42 and are irradiated onto the sample 6.

[0031] FIG. 2 is a schematic cross-sectional view showing an example of the internal configuration of the radiation detector 2. The radiation detector 2 is an SDD (Silicon Drift Detector). The radiation detector 2 includes a cylindrical portion 291, a block 22 that covers and connects to one end of the cylindrical portion 291, and a bottom plate portion 292 that closes the other end of the cylindrical portion 291. The block 22, the cylindrical portion 291, and the bottom plate portion 292 form a housing for the radiation detector 2. The other components of the radiation detector 2 are disposed inside the housing. The block 22 is integrally formed from a ferromagnetic material such as iron. The block 22 has a cone-shaped tip. An entrance 221 is formed at the tip of the block 22, through which fluorescent X-rays are incident to be detected by the radiation detector 2. The entrance 221 is an opening that connects from the outer surface of the block 22 to the internal space of the block 22. The entrance 221 does not have a window material and is not closed. The block 22 is formed as a single unit. The block 22 does not have any gaps connecting to the internal space except for the entrance 221.

[0032] The housing, which is composed of the block 22, cylindrical portion 291, and bottom plate portion 292, contains the radiation detection element 1, magnetic field generation unit 23, collimator 24, circuit board 25, cooling unit 26, heat transfer unit 27, and lead pins 28. The cooling unit 26 is, for example, a Peltier element. The radiation detection element 1 is mounted on the surface of the circuit board 25 and is positioned opposite the incident port 221. The collimator 24 is cylindrical with both ends open and made of an X-ray blocking material. The collimator 24 is positioned between the radiation detection element 1 and the incident port 221. One end of the collimator 24 faces the incident port 221, and the other end faces the surface of the radiation detection element 1. Fluorescent X-rays pass through the incident port 221 and enter the block 22, and the collimator 24 blocks a portion of the fluorescent X-rays. The radiation detection element 1 detects the fluorescent X-rays that enter without being blocked by the collimator 24. The straight line path of the fluorescent X-rays from the entrance 221 to the radiation detection element 1 is not blocked. Furthermore, the straight line path of the fluorescent X-rays from the sample 6 to the radiation detector 2 is not blocked. Therefore, the straight line path of the fluorescent X-rays from the sample 6 to the radiation detection element 1 via the entrance 221 is not blocked by an object such as a window having a window material.

[0033] A magnetic field generator 23 is disposed between the entrance 221 and the collimator 24. The magnetic field generator 23 is disposed in the internal space of the block 22. The magnetic field generator 23 is attached to the block 22. By attaching the magnetic field generator 23 to the block 22, the block 22 holds the magnetic field generator 23. The magnetic field generator 23 is configured by arranging multiple magnets facing each other in the internal space of the block 22. The magnetic field generator 23 generates a magnetic field in a portion of the internal space of the block 22 using the magnets. The magnets used in the magnetic field generator 23 may be permanent magnets or electromagnets. For example, the magnetic field generator 23 is attached to the block 22 by being magnetically attached or glued to the block 22. The magnetic field generator 23 is disposed so that an electric field is generated in at least a portion of the space from the entrance 221 to the radiation detection element 1. Specifically, the multiple magnets included in the magnetic field generator 23 face each other across the space from the entrance 221 to the radiation detection element 1. The magnetic field generating unit 23 generates a magnetic field in at least a part of the space from the entrance 221 to the radiation detection element 1. Therefore, a magnetic field is generated in a part of the space from the sample 6 to the radiation detection element 1.

[0034] A circuit is formed on the circuit board 25, and the preamplifier 21 is mounted on the circuit board 25. The preamplifier 21 is omitted from Fig. 2. The circuit formed on the circuit board 25 is connected to the outside of the radiation detector 2. The application of a voltage to the radiation detection element 1 by the voltage application unit 33 and the output of a signal from the preamplifier 21 are performed via the circuit.

[0035] The back surface of the circuit board 25 is in thermal contact with the heat absorption portion of the cooling unit 26, either directly or via an intervening object. The heat dissipation portion of the cooling unit 26 is in thermal contact with the heat transfer unit 27. The heat transfer unit 27 has a flat portion with which the heat dissipation portion of the cooling unit 26 is in thermal contact, and a portion that penetrates the bottom plate portion 292. Heat from the radiation detection element 1 is absorbed by the cooling unit 26 through the circuit board 25, transferred from the cooling unit 26 to the heat transfer unit 27, and dissipated to the outside of the radiation detector 2 through the heat transfer unit 27. In this manner, the radiation detection element 1 is cooled. The heat transfer unit 27 may be connected to a heat dissipation mechanism such as a heat sink located outside the radiation detector 2. The heat transfer unit 27 may have a heat dissipation structure such as a protrusion for connection to the heat dissipation mechanism. The heat transfer unit 27 may be integrated with the bottom plate portion 292. The radiation detector 2 may not be provided with the heat transfer section 27, and the bottom plate section 292 may also serve as the heat transfer section 27. The radiation detector 2 may further include other components.

[0036] FIG. 3 is a schematic cross-sectional view showing the radiation detection element 1 and the collimator 24. The radiation detection element 1 is a silicon drift type radiation detection element. The radiation detection element 1 is generally flat. For example, the radiation detection element 1 is circular in plan view. The radiation detection element 1 includes a plate-shaped semiconductor portion 12 made of Si (silicon). The semiconductor portion 12 is composed of n-type Si. The radiation detection element 1 has an incident surface 11 located on the incident side where radiation to be detected is incident, and an electrode surface 16 located on the back side of the incident surface 11. A portion of the incident surface 11 is covered with the collimator 24. The radiation detection element 1 is arranged so that the electrode surface 16 faces the circuit board 25 and the incident surface 11 faces the incident opening 221.

[0037] An electrode layer 13 is provided on a portion of the semiconductor portion 12 on the side of the incident surface 11. The electrode layer 13 is doped with a dopant that makes Si a different type of semiconductor from the components of the semiconductor portion 12. The component of the electrode layer 13 is p-type Si, for example, p+Si, in which Si is doped with a specific dopant such as boron. The electrode layer 13 is formed on most of the area along the incident surface 11, including the portion corresponding to the center of the incident surface 11 in a planar view. For example, the electrode layer 13 has a circular shape in a planar view. The electrode layer 13 is formed on all areas of the incident surface 11 corresponding to the portions not covered by the collimator 24. There are portions on the periphery of the area along the incident surface 11 where the electrode layer 13 is not formed.

[0038] A signal output electrode 15, which is an electrode that outputs a signal when radiation is detected, is provided on the portion of the semiconductor portion 12 facing the electrode surface 16. The signal output electrode 15 is made of the same type of Si as the semiconductor portion 12. For example, the signal output electrode 15 is made of n+Si, which is Si doped with a specific dopant such as phosphorus. Furthermore, a plurality of curved electrodes 14, which are arranged in multiple rings in a planar view, are provided on the portion of the semiconductor portion 12 facing the electrode surface 16. The curved electrode 14 is made of a semiconductor of a different type from the semiconductor portion 12, 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, and the signal output electrode 15 is located approximately at the center of the curved electrodes 14. In other words, the curved electrodes 14 surround the signal output electrode 15, and the distances between the signal output electrode 15 and each curved electrode 14 are different.

[0039] Although four curved electrodes 14 are shown in Fig. 3, 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 15 may be disposed at a position other than the center of the multiple curved electrodes 14. The radiation detection element 1 may have a configuration including multiple sets of a signal output electrode 15, multiple curved electrodes 14, and electrode layers 13.

[0040] The innermost curved electrode 14 and the outermost curved electrode 14 are connected to a voltage application unit 33. A voltage is applied from the voltage application unit 33 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 15. For example, an electrical resistance channel connecting two curved electrodes 14 is formed by adjusting the components of the portion located between adjacent curved electrodes 14. 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 outermost curved electrode 14 to the innermost curved electrode 14. That is, the potential of the curved electrodes 14 increases in order from the curved electrodes 14 farthest from the signal output electrode 15 to the curved electrodes 14 closest to the signal output electrode 15. Note that the plurality of curved electrodes 14 may include a pair of adjacent curved electrodes 14 having the same potential.

[0041] The potentials of the multiple curved electrodes 14 generate an electric field (potential gradient) within the semiconductor portion 12 such that the potential is higher the closer to the signal output electrode 15 and lower the farther from the signal output electrode 15. The electrode layer 13 is also connected to a voltage application unit 33. A voltage is applied to the electrode layer 13 from the voltage application unit 33 so that the potential of the electrode layer 13 becomes 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 12 such that the potential is higher the closer to the signal output electrode 15.

[0042] X-rays are irradiated from the irradiation unit 41 onto the sample 6, and fluorescent X-rays are generated in the sample 6 and enter the radiation detector 2. The radiation consisting of fluorescent X-rays mainly passes through the entrance port 221 and enters the inside of the radiation detector 2. A portion of the radiation that enters the inside of the radiation detector 2 is blocked by the collimator 24. The radiation that is not blocked by the collimator 24 enters the radiation detection element 1. The radiation that enters the radiation detection element 1 enters the semiconductor portion 12.

[0043] Radiation incident on the semiconductor portion 12 is absorbed within the semiconductor portion 12, and an amount of charge corresponding to the energy of the absorbed radiation is generated within the semiconductor portion 12. The generated charges are electrons and holes. The generated charges move due to the electric field inside the semiconductor portion 12, and one type of charge flows into the signal output electrode 15 in a concentrated manner. In this embodiment, electrons generated by the incidence of radiation move and flow into the signal output electrode 15. The charge that flows into the signal output electrode 15 is output as a current signal.

[0044] The signal output electrode 15 is connected to a preamplifier 21. The signal output by the signal output electrode 15 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 energy of the radiation. The preamplifier 21 is connected to a signal processing unit 34. When the preamplifier 21 outputs a signal, the radiation detector 2 outputs a signal with an intensity corresponding to the energy of the radiation. The signal processing unit 34 receives the signal output by the radiation detector 2 and detects the signal intensity, thereby detecting a signal value corresponding to the energy of the radiation detected by the radiation detector 2. The signal processing unit 34 counts the signals for each signal value and outputs data indicating the relationship between the signal value and the count number to an analysis unit 35.

[0045] The analysis unit 35 receives data indicating the relationship between the signal value output by the signal processing unit 34 and the count number. The analysis unit 35 generates a spectrum of the radiation incident on the radiation detector 2 based on the data from the signal processing unit 34. The signal value corresponds to the energy of the radiation, and the count number corresponds to the number of times the radiation is detected, so the spectrum of the radiation can be obtained from the relationship between the signal value and the count number. The spectrum indicates the relationship between the energy and intensity of the radiation. Since the radiation incident on the radiation detector 2 is fluorescent X-rays emitted from the sample 6, the spectrum of the fluorescent X-rays emitted from the sample 6 can be obtained.

[0046] The process of counting the signals output by the radiation detector 2 for each signal value may be performed by the analysis unit 35 instead of the signal processing unit 34. The generation of the radiation spectrum may be performed by the signal processing unit 34. The analysis unit 35 stores spectrum data representing the fluorescent X-ray spectrum. The signal processing unit 34 and the analysis unit 35 correspond to the spectrum generation unit. The display unit 36 ​​displays the fluorescent X-ray spectrum. The user can check the fluorescent X-ray spectrum from the sample 6. The analysis unit 35 may further perform information processing based on the fluorescent X-ray spectrum. For example, the analysis unit 35 performs qualitative analysis or quantitative analysis of the elements contained in the sample 6 based on the fluorescent X-ray spectrum from the sample 6.

[0047] In the sample 6 irradiated with X-rays from the irradiation unit 41, photoelectrons are generated in addition to fluorescent X-rays. When the photoelectrons are incident on the radiation detection element 1, a signal caused by the photoelectrons is generated, and the sensitivity for detecting fluorescent X-rays deteriorates. In conventional radiation detectors in which the entrance port is blocked by a window material, the photoelectrons are blocked by the window material, making it difficult for them to enter the radiation detection element.

[0048] In this embodiment, fluorescent X-rays that pass through the entrance 221, which is not blocked by a window material, are detected by the radiation detection element 1. The straight-line path of the fluorescent X-rays from the sample 6 via the entrance 221 to the radiation detection element 1 is not blocked by an object such as a window material. Because the detected fluorescent X-rays do not need to pass through a window material, the radiation detection device 10 can detect fluorescent X-rays that are too low in energy to pass through a window material. This allows the radiation detection device 10 to detect low-energy fluorescent X-rays emitted from the sample 6 and analyze the sample 6 based on the low-energy fluorescent X-rays. For example, qualitative or quantitative analysis of light elements contained in the sample 6 is possible. On the other hand, photoelectrons can easily enter the radiation detector 2 through the entrance 221.

[0049] As shown in FIG. 2 , the radiation detector 2 includes a magnetic field generator 23. The magnetic field generator 23 generates a magnetic field in at least a part of the space from the entrance 221 to the radiation detection element 1. Photoelectrons generated from the sample 6 enter the radiation detector 2 through the entrance 221 and move through the space from the entrance 221 to the radiation detection element 1. A Lorentz force is generated on charged particles moving through the magnetic field. The movement direction of the photoelectrons moving through the space from the entrance 221 to the radiation detection element 1 is bent by the Lorentz force. The photoelectrons, whose movement direction is bent, collide with the magnetic field generator 23 or the collimator 24. In this way, the movement direction of the photoelectrons is bent on the way to the radiation detection element 1, making it difficult for them to enter the radiation detection element 1. Therefore, the incidence of photoelectrons on the radiation detection element 1 is suppressed, the signal caused by the photoelectrons is reduced, and a deterioration in sensitivity for detecting fluorescent X-rays is suppressed.

[0050] The magnets included in the magnetic field generating unit 23 are coated with a substance made of an element with an atomic number smaller than that of the elements constituting the magnets. At least the surfaces facing each other of the multiple magnets that face each other across the space from the entrance 221 to the radiation detection element 1 are coated. For example, the magnets are neodymium magnets, and the surface of the neodymium magnet is coated with nickel, the nickel is coated with aluminum, and the aluminum is coated with carbon.

[0051] When fluorescent X-rays from the sample 6 are incident on the magnet, other fluorescent X-rays are generated from the magnet. Furthermore, photoelectrons whose direction of movement is bent collide with the magnet included in the magnetic field generating unit 23. Characteristic X-rays are generated from the magnet upon collision with the photoelectrons. When X-rays generated from the magnet are incident on the radiation detection element 1, the spectrum of the fluorescent X-rays from the sample 6 includes a system peak resulting from the X-rays generated from the magnet. Because the surface of the magnet is coated, the X-rays generated from the magnet are absorbed by the material coating the magnet and are less likely to be incident on the radiation detection element 1. The material coating the magnet also generates fluorescent X-rays by absorbing the X-rays from the magnet. However, because the material coating the magnet has a smaller atomic number, the fluorescent X-rays generated have lower energy, are weaker in intensity, and have a smaller system peak. Therefore, the coating reduces the system peak resulting from the fluorescent X-rays from the magnet.

[0052] In the magnetic field generating unit 23, the interval between the multiple magnets that face each other across the space from the entrance 221 to the radiation detection element 1 changes along the direction from the entrance 221 toward the radiation detection element 1. The interval between the multiple magnets becomes narrower as they approach the entrance 221 and wider as they approach the radiation detection element 1. For example, the multiple magnets are arranged at an angle to each other so that the interval becomes wider as they approach the radiation detection element 1.

[0053] When fluorescent X-rays are incident on the magnet, they do not enter the radiation detection element 1 and are not detected. Fluorescent X-rays generated in the sample 6 are emitted radially. That is, the fluorescent X-rays spread out the farther they are from the sample 6 and the closer they are to the radiation detection element 1. Because the spacing between the multiple magnets becomes wider the closer they are to the radiation detection element 1, even if the fluorescent X-rays spread out the closer they are to the radiation detection element 1, the probability that they will enter the radiation detection element 1 without entering the magnet increases. This increases the probability that the fluorescent X-rays will be detected. Therefore, the radiation detection device 10 can detect fluorescent X-rays from the sample 6 with high efficiency. The angle at which the multiple magnets are inclined relative to each other may be determined according to the distance from the sample 6 placed on the sample stage 61 to the radiation detection element 1, so that as much fluorescent X-ray as possible can be incident on the radiation detection element 1.

[0054] As described above, the material of the block 22 is a ferromagnetic material. If the material of the block 22 were not a ferromagnetic material, the magnetic field generated by the magnetic field generation unit 23 would leak outside the block 22 and adversely affect the outside of the block 22. For example, if the sample 6 were a magnetic material, the magnetic field would attract the sample 6 to the magnetic field generation unit 23. In this embodiment, since the material of the block 22 is a ferromagnetic material, the magnetic field is shielded by the block 22 and does not leak outside the block 22, so the magnetic field does not adversely affect the outside of the block 22. For example, the sample 6 would not be attracted to the block 22, and a magnetic material could be used as the sample 6.

[0055] The block 22 has a shape that blocks light from the illumination unit 51 so that the light from the illumination unit 51 is less likely to be directly incident on the radiation detection element 1. More specifically, the shape and position of the block 22 are determined so that part of the block 22 is located on a line connecting the incident surface 11 of the radiation detection element 1 and the illumination unit 51 inside the radiation detection device 10. The block 22 is disposed on a linear path of light from the illumination unit 51 to the radiation detection element 1, and blocks light that is linearly irradiated from the illumination unit 51 to the radiation detection element 1. This prevents light from the illumination unit 51 from being incident on the radiation detection element 1.

[0056] When light from the illumination unit 51 is incident on the radiation detection element 1, a current is generated in the radiation detection element 1 in accordance with the incident light, and the current signal output by the radiation detection element 1 increases. The increase in the current signal may cause problems in the radiation detection device 10, such as a malfunction of the preamplifier 21 or a deterioration in the accuracy of radiation detection. In this embodiment, the block 22 prevents light from the illumination unit 51 from being incident on the radiation detection element 1. Therefore, the current generated in the radiation detection element 1 due to the light from the illumination unit 51 is small, and problems caused by an increase in the current signal are prevented. Therefore, problems in the radiation detection device 10 are prevented.

[0057] Because the block 22 is formed as a single unit, there are fewer gaps in the housing of the radiation detector 2 compared to conventional radiation detectors. This makes it difficult for light to enter the interior of the radiation detector 2 from areas other than the entrance 221. Because it is difficult for light to enter the interior of the radiation detector 2, light is further prevented from entering the radiation detection element 1.

[0058] Furthermore, the block 22 and the magnetic field generator 23 are anti-reflection treated to prevent reflection of illumination light for illuminating the sample 6. For example, the surfaces of the block 22 and the magnetic field generator 23 are black. For example, the surface of the block 22 is black because the ferromagnetic material is coated with nickel, the nickel is coated with aluminum, and the aluminum is coated with carbon. The surface of the magnetic field generator 23 is also blackened with carbon. The aluminum surface may be anodized for anti-reflection treatment. For example, the surfaces of the block 22 and the magnetic field generator 23 are roughened to scatter light. Even if illumination light from the illumination unit 51 reflects off the surface of the sample 6 and enters the radiation detector 2, the anti-reflection treatment of the block 22 and the magnetic field generator 23 makes it difficult for the illumination light to be reflected and to reach the radiation detection element 1. This further reduces the incidence of light on the radiation detection element 1.

[0059] As described above, in this embodiment, the incidence of photoelectrons and illumination light on the radiation detection element 1 is suppressed. By suppressing the incidence of photoelectrons on the radiation detection element 1, deterioration of the sensitivity with which the radiation detection device 10 detects fluorescent X-rays from the sample 6 is suppressed. Furthermore, by suppressing the incidence of illumination light on the radiation detection element 1, malfunctions of the radiation detection device 10 are suppressed. Therefore, the radiation detection device 10 can stably detect fluorescent X-rays.

[0060] The radiation detection element 1 may be polygonal in plan view. For example, the radiation detection element 1 may be rectangular in plan view, and the magnetic field generating unit 23 may have two flat magnets arranged facing each other. The two magnets are arranged approximately parallel to the long sides of the radiation detection element 1, with a space from the entrance 221 to the radiation detection element 1 sandwiched between them. By arranging the two magnets approximately parallel to the long sides of the radiation detection element 1, the distance between the two magnets can be reduced without changing the area of ​​radiation incident on the radiation detection element 1, compared to other arrangements, such as an arrangement in which the two magnets are approximately parallel to the short sides of the radiation detection element 1. Reducing the distance between the two magnets strengthens the magnetic field. Photoelectrons change their direction of movement more significantly, making them less likely to be incident on the radiation detection element 1. This more reliably suppresses the incidence of photoelectrons on the radiation detection element 1.

[0061] In this embodiment, the block 22 and the magnetic field generation unit 23 are included in the radiation detector 2, but the block 22 and the magnetic field generation unit 23 may be arranged outside the radiation detector 2. For example, the radiation detector 2 may include a housing that does not include the block 22, and the housing may have an opening that is not covered by a window material, and fluorescent X-rays that pass through the opening are detected by the radiation detection element 1. The magnetic field generation unit 23 is arranged at a position between the sample 6 and the radiation detector 2, and the block 22 is arranged at a position that blocks light that is linearly irradiated from the illumination unit 51 to the radiation detection element 1. Even in this embodiment, the incidence of photoelectrons and illumination light on the radiation detection element 1 is suppressed.

[0062] In this embodiment, the radiation detection element 1 is configured such that the semiconductor is Si, but the radiation detection element 1 may be configured such that it is made of a semiconductor other than Si. In this embodiment, the semiconductor portion 12 is configured such that it is an n-type semiconductor, and the electrode layer 13 and the curved electrode 14 are configured such that it is a p-type semiconductor, but the radiation detection element 1 may be configured such that the semiconductor portion 12 is configured such that it is a p-type semiconductor, and the electrode layer 13 and the curved electrode 14 are configured such that it is an n-type semiconductor. In this embodiment, the radiation detection element 1 is configured such that it is a silicon drift type radiation detection element, but the radiation detection element 1 may be an element made of a semiconductor other than a silicon drift type radiation detection element. Therefore, the radiation detector 2 may be a radiation detector other than an SDD.

[0063] In this embodiment, the radiation detector 2 includes the collimator 24, but the radiation detector 2 may not include the collimator 24. In this embodiment, the radiation detection device 10 includes the X-ray optical element 42, but the radiation detection device 10 may not include the X-ray optical element 42. Alternatively, the radiation detection device 10 may use a radiation detection element 1 other than a semiconductor element.

[0064] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. In other words, embodiments obtained by combining technical means modified appropriately within the scope of the claims are also included in the technical scope of the present invention.

[0065] 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 reference format. Furthermore, the claims use a format in which a claim references two or more other claims (multiple claim format), but this is not limited to this. A multiple claim (multi-multi claim) that references at least one other multiple claim may also be used.

[0066] REFERENCE SIGNS LIST 10 Radiation detection device 1 Radiation detection element 12 Semiconductor section 2 Radiation detector 22 Block 221 Incident port 23 Magnetic field generation section 41 Irradiation section 51 Illumination section 6 Sample

Claims

1. A radiation detection device including an illumination unit that illuminates a sample, an irradiation unit that irradiates the sample with X-rays, and a radiation detection element that detects X-rays generated from the sample, a magnetic field generating unit that generates a magnetic field in a part of a space from the sample to the radiation detection element; a block for holding the magnetic field generating unit, The block is disposed so as to block light from the illumination unit to the radiation detection element. A radiation detection device comprising:

2. The magnetic field generating unit and the block are anti-reflective.

2. The radiation detection device according to claim 1 .

3. The magnetic field generating unit includes a magnet, The magnet is coated with a material made of an element having an atomic number smaller than that of the element contained in the magnet.

2. The radiation detection device according to claim 1 .

4. the magnetic field generating unit includes a plurality of magnets facing each other across a portion of a space from the sample to the radiation detection element, The intervals between the magnets vary along a direction from the sample to the radiation detection element, and become wider as they approach the radiation detection element.

2. The radiation detection device according to claim 1 .

5. The block has an internal space, the magnetic field generating unit is disposed inside the block, The material of the block is ferromagnetic.

2. The radiation detection device according to claim 1 .

6. A straight line path from the sample to the radiation detection element is not blocked.

2. The radiation detection device according to claim 1 .

7. a spectrum generating unit that generates a spectrum of radiation detected by the radiation detection element; a display unit that displays the spectrum generated by the spectrum generation unit; 7. The radiation detection device according to claim 1, further comprising:

8. 1. A radiation detector for detecting fluorescent X-rays, comprising: A block having an internal space; an entrance formed in the block through which the fluorescent X-rays are incident; a radiation detection element facing the entrance; a magnetic field generating unit that is disposed inside the block and generates a magnetic field in a space from the entrance to the radiation detection element, The entrance is unobstructed, and a straight line path from the entrance to the radiation detection element is unobstructed. A radiation detector comprising: