JP6475556B2 - Radiation detector and radiation detection apparatus - Google Patents

Description

  The present invention relates to a radiation detector and a radiation detection apparatus using a semiconductor radiation detection element.

  Some radiation detectors that detect radiation such as X-rays detect radiation using a semiconductor radiation detection element. The radiation detection element is disposed in a hermetically sealed housing. A radiation detector having such a configuration is described in Patent Document 1.

  Some radiation detection devices using a radiation detector irradiate a sample with radiation such as an electron beam or X-ray, and detect radiation generated from the sample irradiated with the radiation with a radiation detector. Such a radiation detection apparatus is, for example, a fluorescent X-ray analysis apparatus. In order to detect radiation from a sample with high efficiency, a radiation detection apparatus that detects radiation using a plurality of radiation detectors has also been developed.

JP 2007-147595 A

  In order to further increase the detection efficiency of radiation from the sample with the radiation detection apparatus, it is conceivable to bring the radiation detector closer to the sample. The closer the radiation detector is to the sample, the more efficiently the radiation from the sample is detected by the radiation detector. However, if the radiation detector is too close to the sample, the housing will interfere with other parts in the radiation detector. Even in the case of a radiation detection apparatus using a plurality of radiation detectors, the housings of the radiation detectors interfere with each other. Therefore, there is a limit to increasing the efficiency of radiation detection by bringing the radiation detector closer to the sample.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a radiation detector that can bring a radiation detector closer to a sample than before and improve the efficiency of radiation detection. And providing a radiation detector.

A radiation detector according to the present invention has a housing having a window through which radiation passes, and a cylindrical shape having both ends open, and is arranged so that one end faces the window, and a part of the radiation that has passed through the window In a radiation detector comprising a shielding body for shielding and a radiation detection element for detecting radiation not shielded by the shielding body, the shielding body has an inner diameter at the other end smaller than the size of the surface of the radiation detection element, and one end smaller outer diameter than the outer diameter of the other end of said housing, wherein a portion of the shape is tapered in which the said window at the distal end.

  In the radiation detector according to the present invention, the outer diameter of the shielding body is continuously changed, and the housing has a shape in which a part of the shape follows the outer diameter of the shielding body. Features.

  The radiation detector according to the present invention is characterized in that an outer surface of the shield is tapered.

  The radiation detector according to the present invention is characterized in that the shield has an inner diameter continuously decreasing from the other end to the one end.

  A radiation detection apparatus according to the present invention includes an irradiation unit that irradiates a sample with radiation, and a radiation detector according to the present invention that detects radiation generated from the sample.

  The radiation detection apparatus according to the present invention includes a plurality of the radiation detectors, and a plurality of the radiation detections in which a window is opposed to the radiation irradiation position around an irradiation axis of the radiation irradiated to the sample by the irradiation unit. A vessel is arranged.

  In the present invention, the radiation detector has a cylindrical shield that shields part of the radiation between the window and the radiation detection element. The shield has an outer diameter at one end facing the window that is smaller than the outer diameter at the other end, and the housing has a tapered shape with a portion of the window as a tip. The tapered portion of the housing can be shaped close to the shield. The size of the housing near the window is reduced, and it is difficult to interfere with other components in the radiation detection apparatus.

  In the present invention, the outer diameter of the shield changes continuously. The housing can have a shape close to the shielding body by forming a part of the shape along the outer diameter of the shielding body.

  In the present invention, the outer surface of the shield is tapered. The housing can have a shape close to the shielding body by forming a part of the shape along the outer diameter of the shielding body.

  In the present invention, a plurality of radiation detectors for detecting radiation generated from the sample are arranged around the irradiation axis of radiation applied to the sample. Since the size of the housing near the window is small, the housings of the plurality of radiation detectors are unlikely to interfere with each other.

  In the present invention, the inner diameter of the shield continuously decreases from the other end to one end. It is possible to prevent the shield from shielding a part of the radiation that enters radially through the window where one end of the shield is opposed to the shield.

  In the present invention, the radiation detector is arranged so as to be closer to the sample than before, and can detect the radiation from the sample with high efficiency. Therefore, the present invention has an excellent effect that the radiation detection apparatus can detect radiation with high sensitivity.

It is a block diagram which shows the structure of the radiation detection apparatus which concerns on Embodiment 1. FIG. It is a typical sectional view of a radiation detector. It is a block diagram which shows the structure of the radiation detection apparatus which concerns on Embodiment 2. FIG. It is a typical top view showing an example of arrangement of a plurality of radiation detectors.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram illustrating a configuration of the radiation detection apparatus according to the first embodiment. The radiation detection apparatus is, for example, a fluorescent X-ray analysis apparatus. The radiation detection apparatus includes an irradiation unit 4 that irradiates a sample 6 with radiation such as an electron beam or X-ray, a sample stage 5 on which a flat sample 6 is held, and a radiation detector 1. Radiation is irradiated from the irradiation unit 4 to the sample 6, radiation such as fluorescent X-rays is generated in the sample 6, and the radiation detector 1 detects the radiation generated from the sample 6. In the figure, the radiation is indicated by arrows. The radiation detector 1 outputs a signal proportional to the detected radiation energy. The radiation detector 1 is connected to a signal processing unit 2 that processes the output signal. The signal processing unit 2 counts each value signal output from the radiation detector 1 and performs a process of generating a relationship between the radiation energy and the count number, that is, a radiation spectrum. The signal processing unit 2 and the irradiation unit 4 are connected to a control unit 3 that controls the entire radiation detection apparatus. The control unit 3 controls operations of the signal processing unit 2 and the irradiation unit 4.

  FIG. 2 is a schematic cross-sectional view of the radiation detector 1. The radiation detector 1 includes a plate-like base 16. A cap-like cover 17 is covered on one surface side of the base 16. The cover 17 has a shape in which a truncated cone is connected to one end of a cylinder, and the other end of the cylinder is joined to the base 16. The base 16 and the cover 17 are made of metal such as iron and are welded. A flat window 18 made of a material that allows radiation to pass through, such as beryllium, is provided at the truncated portion of the cover 17. The inside of the cover 17 is hermetically sealed and decompressed or filled with an inert gas. The base 16, the cover 17, and the window 18 correspond to the housing in the present invention.

  Inside the cover 17, a cylindrical collimator (shielding body) 11, a semiconductor radiation detection element 12, a wiring board 13, and a Peltier element 14 are arranged. The radiation detection element 12 is, for example, an SDD (Silicon Drift Detector). The radiation detection element 12 is mounted on the surface of the wiring board 13 and is disposed at a position facing the window 18. The collimator 11 is formed in a cylindrical shape whose both ends are opened by a material that shields radiation, and is disposed between the radiation detection element 12 and the window 18. One end of the collimator 11 faces the window 18, and the other end is in contact with the surface of the radiation detection element 12. The collimator 11 shields part of the radiation that has passed through the window 18, and the radiation detection element 12 detects radiation that has not been shielded by the collimator 11. Since the collimator 11 shields a part of the radiation, the radiation is prevented from entering the radiation insensitive region of the radiation detection element 12, and the accuracy of radiation detection is maintained.

  The heat absorbing portion of the Peltier element 14 is in thermal contact with the back surface of the wiring board 13. The heat dissipation part of the Peltier element 14 faces the inner surface of the base 16. The radiation detector 1 also includes a cold finger 15 that is in thermal contact with the heat dissipation portion of the Peltier element 14. The cold finger 15 is made of a material having high thermal conductivity. The cold finger 15 includes a plate-like portion that is in thermal contact with the heat dissipation portion of the Peltier element 14 and a bolt-like portion that protrudes from the plate-like portion toward the base 16. The bolt-like portion of the cold finger 15 passes through the base 16 and protrudes from the outer surface of the base 16. The wiring board 13 and the Peltier element 14, and the Peltier element 14 and the cold finger 15 may be in direct contact with each other, or a heat conductive material may be interposed therebetween. A bolt-like portion of the cold finger 15 protruding from the outer surface of the base 16 is connected to a heat radiating portion outside the radiation detector 11. The heat radiating portion is, for example, a heat radiating plate. The radiation detection element 12 is cooled by the Peltier element 14 through the wiring board 13, and the heat of the radiation detection element 12 is conducted from the Peltier element 14 to the cold finger 15 and is radiated from the heat radiation portion. Furthermore, a plurality of lead pins 19 for supplying power and inputting / outputting signals are provided through the base 16.

  The shape of the collimator 11 is such that the outer diameter continuously decreases from the end in contact with the surface of the radiation detection element 12 to the end facing the window 18. For this reason, the outer surface of the collimator 11 is tapered toward the window 18, and the outer diameter of the end facing the window 18 is smaller than the outer diameter of the end in contact with the surface of the radiation detection element 12. . A portion of the cover 17 in the shape of a truncated cone is along the outer diameter of the collimator 11 and is tapered with the window 18 as a tip. Since the cover 17 has a tapered shape, as shown in FIG. 1, the radiation detector 1 can bring the tip closer to the sample 6 as compared with the case where the cover 17 is not tapered. ing.

  By making the outer diameter of the end of the collimator 11 facing the window 18 smaller than the outer diameter of the end in contact with the surface of the radiation detection element 12, the tapered cover 17 with the window 18 as the tip is provided. The shape can be closer to the collimator 11 than before. In particular, since the outer surface of the collimator 11 is tapered toward the window 18, the shape of the cover 17 is made to be a shape along the outer diameter of the collimator 11, so that the cover 17 is made more than the conventional collimator 11. Can be approached. For example, the cover 17 can be brought closer to the collimator 11 than when a collimator having a uniform outer diameter is used. For this reason, the size of the cover 17 in the vicinity of the window 18 can be made smaller than before. For example, the diameter of the cover 17 near the window 18 is smaller than the conventional one.

  The radiation detector 1 is disposed in the radiation detection apparatus so that the outer surface of the window 18 faces the sample 6. The smaller the size of the cover 17 near the window 18, the more difficult the cover 17 interferes with components other than the radiation detector 1 when the window 18 is brought closer to the sample 6. Further, the smaller the size of the cover 17 near the window 18, the more difficult the cover 17 blocks the radiation path of the irradiation unit 4 when the window 18 is brought closer to the sample 6. For this reason, the radiation detector 1 which concerns on this embodiment can be arrange | positioned so that it may approach the sample 6 rather than before. The closer the radiation detector 1 is to the sample 6, the more efficiently the radiation detector 1 detects the radiation from the sample 6. Therefore, the radiation detector 1 according to the present embodiment has a higher efficiency than the conventional one from the sample 6. It is possible to detect radiation. Therefore, the radiation detection apparatus can detect radiation with high sensitivity, and can analyze the sample 6 with higher accuracy than before.

  As shown in FIG. 2, the collimator 11 has a shape in which the inner diameter continuously decreases from the end in contact with the surface of the radiation detection element 12 to the end facing the window 18, similarly to the outer diameter. desirable. When the radiation detector 1 is brought close to the sample 6, the radiation generated from one point of the sample 6 enters the radiation detection element 12 while spreading radially. When the inner diameter is constant from the end of the collimator 1 facing the window 18, a part of the radially incident radiation is shielded by the collimator 1 and is not detected by the radiation detection element 12. In addition, when the difference between the outer diameter and the inner diameter of the collimator 11 is partially reduced, the ability of the collimator 11 to shield the radiation that enters the radiation insensitive region of the radiation detection element 12 is reduced. Accordingly, the collimator 11 is configured such that the inner diameter continuously decreases from the end in contact with the surface of the radiation detection element 12 to the end facing the window 18, so that radiation is emitted to the radiation insensitive region of the radiation detection element 12. While preventing the incident, a part of the radially incident radiation is prevented from being shielded. In the present embodiment, an example in which the outer surface of the collimator 11 is tapered has been shown. However, the shape of the collimator 11 may be a shape in which the outer diameter changes intermittently. The shape may be changed stepwise.

(Embodiment 2)
FIG. 3 is a block diagram illustrating a configuration of the radiation detection apparatus according to the second embodiment. The radiation detection apparatus includes a plurality of radiation detectors 1. The plurality of radiation detectors 1 are connected to a signal processing unit 2. Although two radiation detectors 1 are shown in FIG. 3, the radiation detection apparatus may include three or more radiation detectors 1. The internal configuration of the radiation detector 1 is the same as that in the first embodiment shown in FIG. Other configurations of the radiation detection apparatus are the same as those in the first embodiment. The sample 6 is irradiated with radiation from the irradiating unit 4, and the sample 6 generates radiation such as fluorescent X-rays. In the figure, the radiation is indicated by arrows. Each radiation detector 1 outputs a signal proportional to the energy of the detected radiation, and the signal processing unit 2 counts the signal output from each radiation detector 1 and performs processing for generating a radiation spectrum. The signal processing unit 2 may generate a spectrum obtained by adding the detection results obtained by the plurality of radiation detectors 1 or may generate a spectrum obtained by averaging the detection results obtained by the plurality of radiation detectors 1. The control unit 3 controls operations of the signal processing unit 2 and the irradiation unit 4.

  FIG. 4 is a schematic plan view showing an arrangement example of the plurality of radiation detectors 1. FIG. 4 shows an example in which the radiation detection apparatus includes four radiation detectors 1. The irradiation axis of the radiation applied to the sample 6 by the irradiation unit 4 is orthogonal to FIG. An irradiation point irradiated with radiation on the sample 6 is indicated by 61. In FIG. 4, the cold finger 15 and the lead pin 19 included in the radiation detector 1 are omitted. A plurality of radiation detectors 1 are arranged around the radiation axis around the radiation axis. Each radiation detector 1 is arranged so that the window 18 faces the sample 6. Since radiation generated from the sample 6 by radiation irradiation is emitted in a plurality of directions, by arranging a plurality of radiation detectors 1 around the irradiation axis, the generated radiation is one of the radiation detectors 1. The ratio of incident light becomes higher, and the efficiency of detecting radiation with the radiation detection device becomes higher.

  Also in this embodiment, as in the first embodiment, the outer diameter of the end of the collimator 11 facing the window 18 is smaller than the outer diameter of the end in contact with the surface of the radiation detection element 12. The size of the cover 17 near the window 18 can be made smaller than before. The smaller the size of the cover 17 near the window 18, the more difficult the cover 17 interferes with parts other than the radiation detector 1 when the window 18 is brought closer to the sample 6, and the covers 17 of the plurality of radiation detectors 1. It is hard to interfere with each other. For this reason, in the radiation detector 1 according to the present embodiment, each radiation detector 1 can be arranged closer to the sample 6 than in the past. The rate at which the radiation from the sample 6 enters one of the radiation detectors 1 becomes higher, and the efficiency of detecting the radiation with the radiation detection device increases. Therefore, the radiation detection apparatus can detect radiation with higher sensitivity, and can analyze the sample 6 with higher accuracy.

  The radiation detection apparatus of the present invention may be configured to scan the surface of the sample 6 with the radiation from the irradiation unit 4 and obtain a distribution of the radiation spectrum on the sample 6. In addition, the radiation detector is a radiation detector 1 disposed on the back side of the sample stage 5 by placing the sample 6 on the sample stage 5 in which holes are formed, irradiating the sample 6 with radiation from the back side of the sample stage 5. The form which detects the radiation from the sample 6 may be sufficient.

1 Radiation detector 11 Collimator (shielding body)
DESCRIPTION OF SYMBOLS 12 Radiation detection element 16 Base 17 Cover 18 Window 2 Signal processing part 3 Control part 4 Irradiation part 5 Sample stand 6 Sample

Claims (6)

A housing having a window through which radiation passes, a cylindrical shape having both ends opened, a shield arranged at one end to face the window, and shielding a part of the radiation that has passed through the window, and the shield In a radiation detector comprising a radiation detection element for detecting radiation not shielded by
The shield is smaller than the inner diameter of the other end surface of the radiation detecting element, and the outer diameter of the one end is smaller than the outer diameter of the other end,
The radiation detector according to claim 1, wherein a part of the housing is tapered with the window as a tip. The shield has a continuously changing outer diameter,
The radiation detector according to claim 1, wherein a part of the housing has a shape along the outer diameter of the shield. The radiation detector according to claim 2, wherein the shield has a tapered outer surface. The radiation detector according to any one of claims 1 to 3, wherein the shield has an inner diameter that continuously decreases from the other end to the one end. An irradiation unit for irradiating the sample with radiation; and
A radiation detection apparatus comprising: the radiation detector according to claim 1 that detects radiation generated from a sample. A plurality of the radiation detectors;
The radiation detector according to claim 5, wherein a plurality of the radiation detectors are arranged such that a window is opposed to the radiation irradiation position, with the irradiation unit irradiating the sample with the irradiation axis as a center. Radiation detection device.

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