JP2018151233A - Radiation measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation measuring device in which a radiation detector can be brought into a desirable contact with the surface of a measurement target surface.SOLUTION: A radiation measuring device 1 includes a radiation detector 10, which substantially forms a sheet and is flexible. The radiation detector 10 has an organic semiconductor 20 between a positive electrode 16 and a negative electrode 14, and detects radiation which enters the organic semiconductor 20.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a radiation measurement apparatus that measures radiation.

  The radiation measuring apparatus usually has a radiation detector that detects radiation such as α rays, β rays, gamma rays, and neutron rays. A radiation detector generally converts the number and energy of incident radiation into an electrical signal suitable for display and measurement.

  As the radiation detector, there is a so-called semiconductor detector in which electron-hole pairs are generated and moved in a semiconductor by incident radiation. Examples of such a detector include a so-called Ge detector using a germanium single crystal as a semiconductor and a so-called Si detector using a silicon (silicon) single crystal as a semiconductor. As a device similar to such a semiconductor detector, an element that generates electron-hole pairs in an organic semiconductor by incident radiation and outputs an electrical signal corresponding to the radiation dose has been proposed.

Japanese Patent No. 5233348

  In the radiation measuring apparatus described above, it is required to measure radiation from a measurement target with high accuracy. For example, when measuring β-rays with high accuracy, it is required to measure radiation with the radiation detector in contact with the measurement object. There are various surface shapes of the measurement object, and it is necessary to bend the radiation detector according to the surface shape and bring it into contact with the measurement object. For example, when the measurement target is a tube, it is necessary to bend the radiation detector along its surface.

  Embodiments of the present invention have been made in view of the above circumstances, and an object of the present invention is to provide a radiation measuring apparatus capable of satisfactorily bringing a radiation detector into contact with the surface of a measurement target.

  In order to achieve the above-described object, the radiation measuring apparatus according to the embodiment of the present invention has a substantially sheet shape and is flexible, and detects radiation incident on an organic semiconductor disposed between an anode and a cathode. A radiation detector is provided.

  According to the embodiment of the present invention, the radiation detector can be bent along the surface of the measurement target, and the radiation detector can be brought into contact with the measurement target as much as possible.

It is sectional drawing of the radiation measuring device of 1st Embodiment, and is sectional drawing of the direction orthogonal to the width direction of a radiation detector. It is a top view of the radiation measuring apparatus of 1st Embodiment, and is the figure seen from the measuring object side. It is sectional drawing of the radiation detector of 1st Embodiment, and is sectional drawing which shows the structure of an organic semiconductor and its periphery. It is a block diagram showing typically the system configuration of the radiation measuring device of a 1st embodiment. It is an external view of the radiation measuring apparatus of 1st Embodiment, and is a figure which shows the aspect which curved the radiation detector along the surface of a measuring object. It is a perspective view which shows an example of the display image which a display displays among the radiation measuring devices of 1st Embodiment. It is a perspective view which shows the modification of the display image which a display displays among the radiation measuring devices of 1st Embodiment. It is sectional drawing of the radiation detector of 2nd Embodiment, and is sectional drawing which shows the structure of the organic semiconductor between a cathode and an anode. It is the external view which looked at the anode and the guard ring from the measurement object side among the radiation detectors of 2nd Embodiment. It is sectional drawing of the radiation detector of 3rd Embodiment, and is sectional drawing which shows the structure of the organic semiconductor between a cathode and an anode. It is sectional drawing of the radiation detector of the modification of 3rd Embodiment, and is sectional drawing which shows the structure of the organic semiconductor between a cathode and an anode.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the scope of the invention.

[First Embodiment]
The configuration of the radiation measuring apparatus according to the first embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the radiation measuring apparatus of the present embodiment, and is a cross-sectional view in a direction orthogonal to the width direction of the substantially sheet-shaped radiation detector. In FIG. 1, for ease of understanding, the thickness direction dimension of the radiation detector is shown larger than the width direction and the longitudinal direction, and the display of the cross section of the display is omitted. Yes. FIG. 2 is a top view of the radiation measuring apparatus according to the present embodiment, as viewed from the measurement target side. In FIG. 2, the display of the shield of the radiation detector is omitted for easy understanding. FIG. 3 is a cross-sectional view of the radiation detector of the present embodiment, and is a cross-sectional view showing the configuration of the organic semiconductor and its periphery.

  FIG. 4 is a block diagram schematically showing the system configuration of the radiation measuring apparatus according to the present embodiment. FIG. 5 is an external view of the radiation measuring apparatus according to the present embodiment, and is a view showing an aspect in which the radiation detector is curved along the surface of the measurement target. FIG. 6 is a perspective view showing an example of a display image displayed by the display unit in the radiation measurement apparatus of the present embodiment. FIG. 7 is a perspective view showing a modification of the display image displayed by the display unit in the radiation measurement apparatus of the present embodiment.

  As shown in FIG. 1, the radiation measuring apparatus 1 according to the present embodiment includes a radiation detector 10 that detects radiation from a measurement target, and a display 40 that can display information related to radiation detected by the radiation detector 10. And have. Further, the radiation measuring apparatus 1 is a device that can control the display of the display 40 by processing an electrical signal output from the radiation detector 10 in response to the incidence of radiation from a measurement target (hereinafter referred to as a processing device). 30.

  The display 40 of this embodiment is overlapped with the radiation detector 10 and coupled to the substrate 12. Further, the display device 40 is configured to bend together with the radiation detector 10 described above. As shown in FIGS. 1 and 2, the processing device 30 is integrally coupled to the radiation detector 10. Specifically, the processing device 30 is coupled to an edge 12 a extending in the width direction W of the substrate 12 of the radiation detector 10. Has been. The processing device 30 of the present embodiment has a substantially rectangular parallelepiped shape and extends along the edge 12a.

  The radiation measurement apparatus 1 is for measuring radiation emitted from a measurement target, and specifically detects β rays, γ rays, neutrons, and the like. The radiation measurement apparatus 1 measures radiation from the measurement target in a state where the radiation detector 10 is in contact with the surface 5 of the measurement target, preferably in a close contact state.

(Configuration example of radiation detector)
As shown in FIGS. 1 and 2, the radiation detector 10 has a substantially sheet shape and is flexible. As shown in FIG. 5, it is comprised so that it may bend according to the shape of the surface 5 of a measuring object. The thickness direction of the radiation detector 10 is indicated by an arrow T in FIG. Further, as shown in FIGS. 1 and 2, the radiation detector 10 of the present embodiment has a substantially rectangular shape extending in the width direction W and the longitudinal direction L perpendicular to the thickness direction T, and more specifically. Has a rectangular shape. The width direction of the radiation detector 10 is indicated by an arrow W in FIG. 2, and the longitudinal direction is indicated by an arrow L in FIG.

  As shown in FIG. 1, the radiation detector 10 includes a substrate 12, and the substrate 12 is a substantially sheet-like and flexible electrical insulator. The substrate 12 can be made of a material such as synthetic resin. For the substrate 12, a substrate having a thickness of, for example, several tens of μm is used.

  The radiation detector 10 has a cathode 14 and an anode 16, and an organic semiconductor 20 disposed between the two electrodes 14 and 16. More specifically, the radiation detector 10 includes a single cathode 14, a single organic semiconductor 20, and a plurality of anodes 16. In the present embodiment, the plurality of anodes 16 are electrode arrays that are arranged along the same surface 20 a of the organic semiconductor 20 at intervals in the width direction W and the longitudinal direction L.

  In the thickness direction T of the radiation detector 10, the substrate 12, a single cathode 14, an organic semiconductor 20, and a plurality of anodes 16 are stacked in this order. In the present embodiment, the plurality of anodes 16 are arranged in a matrix on the organic semiconductor 20. A predetermined voltage, a so-called reverse bias voltage, is applied between each anode 16 and the cathode 14 constituting the electrode array, and an electric field is generated in the organic semiconductor 20 between each anode 16 and the cathode 14.

  The organic semiconductor 20 is an organic substance exhibiting properties as a semiconductor, and is composed of, for example, a high molecular organic compound. The organic semiconductor 20 has a substantially sheet shape and is flexible. The organic semiconductor 20 can be made of a material such as a quinacridone organic compound or a phthalocyanine organic compound.

  As shown in FIGS. 1 and 3, the organic semiconductor 20 of this embodiment is sandwiched between a plurality of anodes 16, that is, an electrode array, and a single cathode 14. An anode 16 is disposed on the measurement target side, that is, the side on which radiation is incident, and a cathode 14 is disposed on the side opposite to the side on which radiation is incident, that is, on the substrate 12 side.

  The cathode 14 and the anode 16 are substantially sheet-like and flexible conductors. In the present embodiment, the cathode 14 is formed in a thin film shape between the substrate 12 and the organic semiconductor 20. Similarly, each anode 16 constituting the electrode array is also formed in a thin film shape on the surface 20 a of the organic semiconductor 20.

  The cathode 14 and the anode 16 can be made of, for example, indium tin oxide (ITO), gold, or silver. The cathode 14 can be formed on the substrate 12 by vapor deposition or the like. Similarly, the plurality of anodes 16 can be formed on the organic semiconductor 20 by vapor deposition or the like.

  As shown in FIG. 3, the thickness of the cathode 14 (indicated by the dimension t1) and the thickness of the anode 16 (indicated by the dimension t3) are about several tens of nm. The thickness (indicated by dimension t2) of the organic semiconductor 20 is about several tens of μm.

  As shown in FIG. 2, the cathode 14 extends in the width direction W and the longitudinal direction L of the radiation detector 10 along the substrate 12. In the present embodiment, the cathode 14 has a rectangular shape. The organic semiconductor 20 extends in the width direction W and the longitudinal direction L along the cathode 14, and has a rectangular shape with substantially the same dimensions as the cathode 14.

  On the other hand, the plurality of anodes 16 are arranged in a matrix along the organic semiconductor 20 at predetermined intervals in the width direction W and the longitudinal direction L. Each anode 16 constituting the electrode array has a square shape, and the size thereof is 1 cm × 1 cm. Each anode 16 is arranged so as to oppose the cathode 14 and the thickness direction T of the radiation detector 10 with the organic semiconductor 20 interposed therebetween (see FIG. 3).

  Each anode 16 is electrically connected to a processing device 30 via a corresponding conductor 15 as shown in FIG. Similarly, the cathode 14 is electrically connected to the processing device 30 via the conductor 13. The conductors 13 and 15 can be made of a material such as gold, for example. A predetermined voltage (reverse bias voltage) is applied between the two electrodes 14 and 16 via the conductors 13 and 15 in the thickness direction T of the radiation detector 10.

  In addition, the radiation detector 10 of the present embodiment includes a conductor (hereinafter referred to as a shield) 18 that can shield electromagnetic waves or light traveling toward the organic semiconductor 20 on the measurement target side from the anode 16 and the cathode 14. The shield 18 is electrically insulated from the above-described cathode 14 and anode 16 and is electrically connected to a ground (not shown). The shield 18 can be made of a metal material such as aluminum or copper.

  The shield 18 has a shallow dish shape made of a metal material, and extends in the width direction W and the longitudinal direction L with a predetermined interval from the anode 16 in the thickness direction T of the radiation detector 10. The shield 18 covers the anode 16, the organic semiconductor 20, and the cathode 14 on the measurement target side from the substrate 12, and electrical insulation with these is ensured. The edge of the shield 18 is coupled to the substrate 12 which is an electrical insulator.

  It is also preferable that the shield 18 can shield a part of the radiation emitted from the measurement target, for example, α rays and β rays. For example, it is possible to detect β rays with high accuracy by limiting the incidence of α rays to the organic semiconductor 20 and by using a material and thickness that allow β rays to pass through. The shield 18 is also preferably configured to shield α rays and β rays in order to detect γ rays with high accuracy.

In the radiation detector 10 configured as described above, a predetermined voltage (reverse bias voltage) is applied between each anode 16 and the cathode 14. Due to the voltage, an electric field is generated in the organic semiconductor 20 between each anode 16 and the cathode 14. In this state, as shown by an arrow R1 in FIG. 3, when radiation (for example, β-rays) from a measurement object is incident, a pair of electrons e ⁻ and holes h ⁺ , so-called electrons, is entered in the organic semiconductor 20. Electron-hole pairs are generated. Furthermore, the electron e ⁻ of the electron hole pair moves to the anode 16 in the organic semiconductor 20, and the hole h ⁺ moves to the cathode 14.

  During the movement, a charge of several picocoulombs [pC] is induced in the anode 16. This amount of charge is ideally proportional to the energy imparted to the organic semiconductor between the anode 16 and the cathode 14 by the incidence of radiation. Due to the induced charges, a weak current that changes in a pulsed manner flows between the anode 16 and the cathode 14.

  In this way, in the radiation detector 10, a pulsed electric signal (hereinafter simply referred to as “pulse signal”) indicating the incidence of the radiation is generated in response to the incidence of the radiation on the organic semiconductor 20, and the radiation is generated. Output from the detector 10. The pulse signals are received by the processing device 30 and the number and energy thereof are measured. By counting (counting) the number of the pulse signals per unit time, the radiation intensity incident on the organic semiconductor 20 can be calculated.

(Configuration example of display unit)
As shown in FIG. 1, the display device 40 is arranged on the opposite side to the measurement target side (the side on which radiation is incident) in the thickness direction T of the radiation detector 10. In other words, the display device 40 is disposed on the opposite side of the substrate 12 in the thickness direction T from the side on which the organic semiconductor 20 is disposed (the side on which radiation is incident). The display 40 is controlled by the processing device 30 and displays information related to the radiation detected by the radiation detector 10.

  In the present embodiment, the display device 40 is an organic EL panel having a substantially sheet shape and having flexibility, a so-called flexible organic EL panel. The display 40 has a screen 41 on the outer side, that is, the side opposite to the side on which the radiation is incident. The display 40 can display various types of information including information related to the radiation detected by the radiation detector 10 on the screen 41. An example of “information about radiation” displayed on the screen 41 will be described later.

  As shown in FIGS. 6 and 7, the screen 41 of the display 40 has a plurality of display areas 44. The plurality of display areas 44 correspond one-to-one to the plurality of anodes 16 (see FIG. 2) which are electrode arrays. In the present embodiment, each display region 44 is disposed at a position facing the corresponding anode 16 and the thickness direction T of the radiation detector 10 (see FIG. 1).

  Each display area 44 constituting the screen 41 includes a plurality of light emitting elements (not shown) arranged at intervals. In the present embodiment, each display region 44 includes a light emitting element that emits red, a light emitting element that emits green, and a light emitting element that emits blue. These light emitting elements are arranged at intervals. Each display region 44 preferably corresponds to one of the plurality of anodes 16.

  The display 40 configured as described above can display various colors, characters, and the like in the display areas 44 of the screen 41, and information on radiation detected by the radiation detector 10 from the measurement target. Information indicating the intensity of radiation, so-called “radiation intensity”, can be displayed in the form of color (see FIG. 6), characters (see FIG. 7), light emission pattern, and the like. The display mode of each display area 44 of the display device 40 is controlled by the processing device 30.

(Example of processing device configuration)
As shown in FIG. 4, the processing device 30 is a functional unit (hereinafter referred to as a signal measuring unit) that measures an electrical signal (pulse signal) output from the radiation detector 10 in response to radiation incident on the organic semiconductor 20. ) 32. Further, a functional unit (hereinafter referred to as a radiation intensity calculation unit) 34 that calculates radiation intensity based on the pulse signal measured by the signal measurement unit 32 and various constants for calculating the radiation intensity are stored in advance. And a memory 35.

  The processing device 30 includes a functional unit (hereinafter referred to as a display control unit) 36 that causes the display 40 to display information related to radiation detected by the radiation detector 10. The information regarding the radiation includes information indicating the radiation intensity calculated by the radiation intensity calculation unit 34. The display control unit 36 of the present embodiment controls each display area 44 constituting the screen 41 of the display device 40 to display information representing the radiation intensity in each display area 44.

  Moreover, the processing device 30 of this embodiment has the secondary battery 38 as a power supply. The secondary battery 38 can supply power to the radiation detector 10 and the display 40. The electric power supplied to the radiation detector 10 is used for applying a reverse bias voltage.

  The signal measuring unit 32 is an electrical signal output from the radiation detector 10 in response to the incidence of radiation on the organic semiconductor 20, more specifically, between the cathode 14 and the anode 16 due to the incidence of radiation on the organic semiconductor 20. The change of the pulsed current that occurred in the meantime is measured.

  The signal measuring unit 32 can be realized using an amplifier that amplifies the pulse signal, a counter that counts the number of amplified pulse signals, an A / D converter, and the like. As the amplifier, for example, a charge amplifier that outputs a signal proportional to the total amount of charges (that is, an integrated value of current) is used. The counter counts the number of pulse signals amplified by the amplifier per unit time. The number of pulse signals per unit time is proportional to the radiation intensity.

  The radiation intensity calculator 34 calculates the radiation intensity based on the number of pulse signals per unit time and a predetermined conversion factor. The radiation intensity includes, for example, physical quantities such as a dose rate [μSv / h] of radiation from the measurement target and radioactivity [Bq] of the measurement target. The radiation intensity calculation unit 34 can be realized using an IC or a processor.

  In the memory 35, a proportionality constant (hereinafter referred to as a dose rate conversion coefficient) indicating the relationship between the number of pulse signals per unit time and the dose rate of radiation from the measurement object is stored in advance. The memory 35 may store in advance a proportionality constant (hereinafter referred to as a radioactivity conversion coefficient) indicating the relationship between the number of pulse signals per unit time and the radioactivity to be measured. The dose rate conversion factor and the radioactivity conversion factor can be obtained in advance by performing a fitting experiment or simulation.

  The radiation intensity calculation unit 34 calculates the dose rate of radiation from the measurement target based on the number of pulse signals per unit time measured by the signal measurement unit 32 and the dose rate conversion coefficient stored in the memory 35 in advance. To do. The radiation intensity calculation unit 34 may calculate the radioactivity of the measurement target based on the number of pulse signals per unit time and the radioactivity conversion coefficient stored in the memory 35 in advance.

  The signal measuring unit 32 includes a functional unit that measures the height of each pulse signal, that is, the energy of each pulse signal, and weights the number of pulse signals per unit time based on the energy. Is preferred. It is also preferable that the radiation intensity calculation unit 34 corrects the value of the radiation intensity, for example, the dose rate [μSv / h] and the radioactivity [Bq] based on the energy.

  The processing device 30 performs the pulse signal measurement and the radiation intensity calculation described above for each of the plurality of anodes 16. The signal measuring unit 32 measures a pulse signal corresponding to each anode 16 constituting the electrode array. The radiation intensity calculator 34 calculates the radiation intensity corresponding to the electrode 16 based on the measured pulse signal. The calculated radiation intensity is stored in the memory 35. From these radiation intensities, a two-dimensional distribution of radiation intensities can be obtained.

  In the processing device 30, the display control unit 36 displays the radiation intensity calculated corresponding to each electrode 16 constituting the electrode array in the display area 44 corresponding to the electrode 16. In the present embodiment, as shown in FIG. 6, a color representing the corresponding radiation intensity is displayed in color in each display area 44. For example, by displaying red, green, and blue in each display area 44 in accordance with the dose rate [μSv / h] and the radioactivity [Bq], a two-dimensional distribution of radiation intensity is displayed on the screen 41 in a so-called color contour display. Can be displayed.

  As in the modification shown in FIG. 7, it is also preferable to display characters, more specifically numerical values, in each display area 44 as information representing the radiation intensity. It is preferable to display a numerical value approximately proportional to the dose rate and radioactivity.

  As described above, the radiation measuring apparatus 1 according to the present embodiment has a substantially sheet shape and is flexible and includes the organic semiconductor 20 disposed between the anode 16 and the cathode 14. A radiation detector 10 for detecting radiation incident on the semiconductor 20 is included. In addition, the radiation measuring apparatus 1 is disposed on the side opposite to the measurement target side in the thickness direction T of the radiation detector 10, and is a display 40 that can display information on the radiation detected by the radiation detector 10. It was supposed to have.

  According to this embodiment, even when a structure with a curved surface such as a pipe is a measurement target, radiation such as β rays is detected in a state where the radiation detector is in contact with the surface of the measurement target. Information regarding the detected radiation can be displayed in real time on the spot. An operator who measures the radiation to be measured using the radiation measuring apparatus 1 can easily obtain information such as radiation intensity. Further, when the radiation is not measured, the radiation measuring apparatus 1 can be carried in a bent state, and the portability of the radiation measuring apparatus is improved.

  In the present embodiment, the processing device 30 calculates the radiation intensity by counting the number of pulse signals output from the radiation detector per unit time or measuring the energy of each pulse signal. However, the method by which the processing device according to the present invention calculates the radiation intensity is not limited to this mode. For example, it is possible to calculate the radiation intensity by performing a so-called “current readout” in which the amount of charge induced in the anode per unit time, that is, the anode 16 is read as an average value of a certain time. . In this case, the signal measuring unit 32 described above can be realized by using a current amplifier instead of the charge amplifier.

[Second Embodiment]
The radiation detector of 2nd Embodiment is demonstrated with reference to FIG.8 and FIG.9. FIG. 8 is a cross-sectional view of the radiation detector of the present embodiment, and is a cross-sectional view showing the configuration of the organic semiconductor between the cathode and the anode. FIG. 9 is an external view of the anode and the guard ring in the radiation detector of the present embodiment as viewed from the measurement target side. In FIG. 9, the shield display of the radiation detector is omitted for easy understanding. This embodiment is different from the first embodiment only in the configuration of the radiation detector. About the structure substantially common to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 8, in the radiation detector of the present embodiment, a guard ring 17 is disposed on the same surface 20a of the organic semiconductor 20 so as to correspond to each anode 16B constituting the electrode array. The guard ring 17 surrounds the corresponding anode 16B with an interval in a direction perpendicular to the thickness direction T of the radiation detector. The guard ring 17 is a conductor and is electrically grounded.

  In the present embodiment, as shown in FIG. 9, the plurality of guard rings 17 are arranged at predetermined intervals in the width direction W and the longitudinal direction L of the radiation detector. The plurality of guard rings 17 surround the corresponding anodes 16B over the entire circumference. Each guard ring 17 has a quadrangular shape and surrounds a corresponding square-shaped anode 16B.

  According to this embodiment, when a reverse bias voltage is applied between the anode 16B and the cathode 14, an electric field is generated in the organic semiconductor 20, and when no radiation is incident on the organic semiconductor 20, the anode 16B and It is possible to suppress a weak current, that is, a so-called leak current, from flowing between the cathode 14. The radiation detector according to the present embodiment can cause a current corresponding to the leakage current to flow between the anode 16 </ b> B and the guard ring 17 along the surface 20 a of the organic semiconductor 20. Noise contained in the electrical signal output from the radiation detector 10 in response to the incidence of radiation on the organic semiconductor 20 can be reduced.

  In the present embodiment, the guard ring 17 has a quadrangular shape and surrounds the corresponding anode 16B over the entire circumference. However, the guard ring according to the present invention is limited to this form. It is not something. The guard ring according to the present invention may at least partially surround the corresponding anode. For example, the guard ring may be C-shaped.

[Third Embodiment]
The radiation detector of 3rd Embodiment is demonstrated with reference to FIG.10 and FIG.11. FIG. 10 is a cross-sectional view of the radiation detector of the present embodiment, and is a cross-sectional view showing the configuration of the organic semiconductor between the cathode and the anode. FIG. 11 is a cross-sectional view of a radiation detector according to a modification of the present embodiment, and is a cross-sectional view showing a configuration of an organic semiconductor between a cathode and an anode. This embodiment is different from the first embodiment only in the configuration of the organic semiconductor in the radiation detector. About the structure substantially common to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 10, in the radiation detector of the present embodiment, the organic semiconductor 20 </ b> C includes a plurality (two) layers 24 and 26 stacked between the cathode 14 and the anode 16. Of these two layers 24 and 26, a layer (hereinafter referred to as a high-sensitivity layer) 24 having higher sensitivity to radiation than the other is disposed on the side opposite to the measurement target side, that is, the cathode 14 side. .

  On the other hand, a layer (hereinafter referred to as a low sensitivity layer) 26 having a relatively low sensitivity to radiation is disposed on the measurement target side, that is, the anode 16 side. In the radiation detector of this embodiment, a substrate 12, a single cathode 14, a high sensitivity layer 24, a low sensitivity layer 26, and a plurality of anodes 16 (electrode array) are laminated in this order.

  The low sensitivity layer 26 is made of the same material as the organic semiconductor 20 (see FIG. 3) described above. The low sensitivity layer 26 can be composed of, for example, a polymer organic compound.

  The high-sensitivity layer 24 uses the same material as the low-sensitivity layer 26, that is, an organic compound as a base material. In this embodiment, a substance 27 that emits light upon receiving radiation (hereinafter referred to as a luminescent substance) is mixed with the organic compound. Has been. The luminescent material 27 is contained in the highly sensitive layer 24 in a substantially uniform manner. Note that the thickness of the high-sensitivity layer 24 in the thickness direction T of the radiation detector 10 may be about 100 nm or more. This is because the light emitted from the luminescent material 27 can be photoelectrically converted at a distance of about 100 nm in the base material.

  The luminescent material 27 is a so-called scintillator that can emit light upon receiving radiation such as β rays or γ rays. As the luminescent material 27, for example, a single crystal of bismuth germanate (BGO) is used. Note that various substances can be used as the light-emitting substance according to the present invention as long as the substance emits light upon receiving radiation. Note that, as the base material of the high-sensitivity layer 24, a material capable of photoelectric conversion with respect to light having substantially the same wavelength as the light emitted from the light emitting material 27 is used.

As indicated by an arrow R2 in FIG. 10, when the radiation from the measurement object enters the high-sensitivity layer 24, it hits the luminescent material 27 with a relatively high probability. The luminescent material 27 receives radiation and emits light (so-called scintillation light). The light emitted from the luminescent material 27 generates electron-hole pairs in the base material of the high-sensitivity layer 24. The electrons e ⁻ move toward the anode 16 in the high sensitivity layer 24 and the low sensitivity layer 26. On the other hand, the holes h ⁺ move toward the cathode 14 through the high sensitivity layer 24.

(Modification)
In the above description, the high-sensitivity layer 24 is assumed that the light-emitting substance 27 that emits light upon receiving radiation is mixed with the base material (organic compound). The substance to be mixed is not limited to the light emitting substance.

  For example, as in the modification shown in FIG. 11, the high-sensitivity layer 24B has the same substance as the low-sensitivity layer 26, that is, an organic compound as a base material, It may be mixed. In the modification, the anode 16B and the guard ring 17 surrounding the anode 16B are disposed on the surface 20a on the measurement target side of the organic semiconductor 20C.

For example, boron carbide (B ₄ C), lithium fluoride (L _i F), or lithium nitride (Li ₃ N) is used as the nuclear reactant 28. Note that various materials can be used as the nuclear reactant according to the present invention as long as the material reacts with neutrons. The nuclear reactant 28 is contained in an evenly dispersed manner in the high sensitivity layer 24B.

As indicated by an arrow R3 in FIG. 11, when the neutron out of the radiation from the measurement object enters the high sensitivity layer 24B, it hits the nuclear reactant with a relatively high probability. Nuclear reactant reacts with neutrons and emits γ rays. The γ rays and the like emitted from the nuclear reactant generate electron-hole pairs in the base material of the high sensitivity layer 24B. The holes h ⁺ move toward the cathode 14 through the high sensitivity layer 24B.

(Technical significance of high sensitivity layer and low sensitivity layer)
The number of electrons and holes generated by radiation incident on the organic semiconductor depends on the energy of the radiation. However, not all of the electrons / holes generated in the organic semiconductor contribute to the electrical signal, and some of the electrons / holes generated in the organic semiconductor move into the organic semiconductor while moving to the electrode. May be trapped (absorbed). That is, the number of electrons reaching the anode and the number of holes reaching the cathode may be reduced as compared to electron-hole pairs generated by radiation incidence.

  The degree Q at which such a phenomenon occurs can be expressed using the following mathematical formula.

上記の数式において、
Ｅ：有機半導体の電極間の電場
Ｚ：有機半導体の厚さ（図１０及び図１１参照）
ｚ：電子／正孔が生じた位置であり、電極（陰極１４）からの距離
τ：電子／正孔の移動度（τ_ｅ／τ_ｈ）
μ：電子／正孔の寿命（μ_ｅ／μ_ｈ）
ｎ：生じた電子（電荷）／正孔の数
ｅ₀：電気素量（素電荷）
正孔、電子ともに十分τμが大きい場合、有機半導体内のどの場所で電子正孔対が生じても得られる電気信号は一定になる。しかし、正孔のτ_ｈμ_ｈは、一般的に電子のτ_ｅμ_ｅに比べて１桁程度小さいため、正孔が、移動先の電極である陰極１４から離れた位置で発生した場合、十分な信号を得ることができない。

In the above formula,
E: Electric field between electrodes of organic semiconductor Z: Thickness of organic semiconductor (see FIGS. 10 and 11)
z: position where electron / hole is generated, distance from electrode (cathode 14) τ: mobility of electron / hole (τ _e / τ _h )
μ: Life of electron / hole (μ _e / μ _h )
n: number of generated electrons (charge) / number of holes e ₀ : elementary electric charge (elementary charge)
When both .tau..mu..mu. Are sufficiently large for both holes and electrons, the electric signal obtained is constant regardless of where the electron-hole pair occurs in the organic semiconductor. However, since τ _h μ _{h of} holes is generally about an order of magnitude smaller than τ _e μ _{e of} electrons, when holes are generated at a position away from the cathode 14 that is the destination electrode, A sufficient signal cannot be obtained.

  In the above-described example, the high-sensitivity layers 24 and 24B are disposed in the vicinity of the cathode 14 that is a hole transfer destination. As a result, the radiation incident on the organic semiconductor 20C has a probability of generating electron-hole pairs in the high-sensitivity layers 24, 24B near the cathode 14, and a probability of generating electron-hole pairs in the low-sensitivity layer 26. Higher than By generating electron-hole pairs in the vicinity of the cathode 14, it is possible to reduce the number of holes trapped during the movement to the cathode 14, although generated in the organic semiconductor 20 </ b> C. Thereby, the radiation detector 10 can output the electrical signal according to the incidence of the radiation on the organic semiconductor 20C with higher accuracy.

  In the present embodiment, the portion other than the high sensitivity layers 24 and 24B in the organic semiconductor 20C is the low sensitivity layer 26. This is because the stray capacity is increased when the organic semiconductor is made of only the high-sensitivity layers 24 and 24B and the thickness of the organic semiconductor is reduced as compared with the above-described example. When the stray capacitance is relatively large, noise included in the electric signal output from the radiation detector due to the stray capacitance is also relatively large.

  In order to suppress the noise, it is necessary to secure the thickness of the organic semiconductor 20 (indicated by the dimension Z in FIGS. 10 and 11) to some extent. When the dimension of each electrode (anode) 16 and 16B constituting the electrode array is, for example, 1 cm × 1 cm, it is necessary to secure the thickness of the organic semiconductor 20C to about 10 μm.

  Therefore, in the present embodiment, the organic semiconductor 20C is provided by disposing the low-sensitivity layer 26 in addition to the high-sensitivity layers 24 and 24B between the anodes 16 and 16B and the cathode 14 constituting the electrode array. The thickness is secured. Thereby, noise resulting from stray capacitance can be suppressed.

  In the radiation detector of the present embodiment, the substance mixed in the base material of the high-sensitivity layer is a luminescent substance that emits light upon receiving radiation, or a nuclear reaction that emits gamma rays or the like through a nuclear reaction with neutrons. Although it is a substance, the substance mixed with the base material (organic compound) in the high-sensitivity layer according to the present invention is not limited to these. The high-sensitivity layer may be, for example, a material in which a metal such as lead having a higher density than the base material is mixed. For example, it is also preferable to form a high-sensitivity layer by mixing lead powder, which is a γ-ray scatterer, with a base material (organic compound). Compton scattering occurs when radiation enters the high-sensitivity layer and γ rays of the radiation hit lead. It is also possible for gamma rays whose direction has been changed by Compton scattering to generate electron-hole pairs in the base material.

[Other Embodiments]
In each of the embodiments described above, the radiation detector 10 is an electrode array in which the anodes 16 are arranged at intervals on the same surface 20a of the organic semiconductors 20 and 20C, and the thickness direction T of the radiation detector 10 is the same. However, the cathode 14 facing the electrode array is singular, but the radiation detector according to the present invention is not limited to this embodiment. In the radiation detector according to the present invention, at least one of the anode and the cathode may be an electrode array.

  In the radiation detector according to the present invention, for example, the cathode may be an electrode array, and the anode facing the electrode array in the thickness direction may be single. Further, both the cathode and the anode may be an electrode array, and the plurality of anodes and the plurality of cathodes may be arranged to face each other in the thickness direction of the radiation detector.

  Moreover, although the radiation detector 10 of each embodiment mentioned above shall have the single organic semiconductor 20 and 20C, the radiation detector which concerns on this invention is not limited to this aspect. In the radiation detector according to the present invention, an organic semiconductor may be disposed between the cathode and the anode. For example, a plurality of organic semiconductors may be arranged corresponding to each other between a plurality of anodes and a plurality of cathodes facing each other in the thickness direction of the radiation detector.

  Further, in each of the above-described embodiments, the radiation detector 10 causes the radiation emitted from the measurement target to pass through the shield 18 and the electrodes (the anode 16 or the cathode 14) and enter the organic semiconductors 20 and 20C. Although electron-hole pairs are generated in the semiconductors 20 and 20C, the radiation detector according to the present invention is not limited to this mode. For example, a scintillator that emits light upon receiving ionizing radiation is disposed between the two electrodes 14 and 16 and the measurement target, and the light emitted from the scintillator is incident on the organic semiconductors 20 and 20C. May be.

  Further, in each of the embodiments described above, the display 40 is a flexible organic EL panel having a substantially sheet shape and flexibility. However, the display according to the present invention is limited to this mode. Is not to be done. The display device according to the present invention only needs to include at least one light emitting element and display information on radiation such as radiation intensity by the light emitting element.

  In the display device 40 according to the present invention, for example, a plurality of light emitting diodes (LEDs) may be dispersed and arranged as light emitting elements at intervals. By controlling lighting and extinguishing of each of the light emitting diodes of a plurality of light emitting colors (colors), it becomes possible to display information on the radiation detected by the radiation detector, such as radiation intensity, in color. In this case, it is preferable that the light emitting diodes are arranged corresponding to the respective anodes constituting the electrode array in the radiation detector.

  Further, the display device according to the present invention can be constituted by a single light emitting diode (light emitting element). The light emission pattern of the light emitting diode, more specifically, a lighting or blinking pattern or the like may be changed according to the radiation intensity or the like.

  Moreover, in each embodiment mentioned above, the processing device 30 shall be couple | bonded with the edge 12a of the board | substrate 12 extended in the width direction of the radiation detector 10, and shall extend along the said edge 12a. However, the processing device according to the present invention is not limited to this mode. The processing device may not be coupled to the radiation detector or the display but may be electrically connected to the radiation detector and the display via a cable or the like. In this case, the processing device can also be configured using a general PC or amplifier.

  Moreover, the processing device 30 of this embodiment measures the electrical signal output from the radiation detector 10 in response to the incidence of radiation on the organic semiconductors 20 and 20C, and determines the dose rate based on the measured electrical signal [ The radiation intensity such as μSv / h] and radioactivity [Bq] is calculated, and the radiation intensity is displayed on the display 40 as information representing the radiation intensity. The function of the processing device according to the present invention is as follows: It is not limited to this aspect. The processing device according to the present invention may be any device that can process the electrical signal generated in the radiation detector by the incidence of radiation and control the display of the display based on the electrical signal. For example, an electric signal (pulse signal) from the radiation detector may be amplified, and a light emitting element provided in the display may blink according to the pulse signal.

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1: radiation measuring device, 5: surface of measurement object, 10: radiation detector, 12: substrate, 12a: edge (radiation detector, substrate), 14: cathode (electrode, electrode array), 16: anode (electrode) , Electrode array), 18: electromagnetic shield, 20, 20C: organic semiconductor, 20a: surface (organic semiconductor), 24, 24B: high sensitivity layer (organic semiconductor), 26: low sensitivity layer, 27: luminescent material, 28: Nuclear reaction material, 30: processing device, 32: signal measurement unit (processing device), 34: radiation intensity calculation unit (processing device), 36: display control unit (processing device), 40: display (organic EL panel), 41: Screen, 44: Display area

Claims (15)

A radiation detector that is substantially sheet-like and flexible, and detects radiation incident on an organic semiconductor disposed between an anode and a cathode,
A radiation measurement apparatus comprising: A display that is disposed on the opposite side of the measurement object in the thickness direction of the radiation detector, and that can display information on the radiation detected by the radiation detector;
Measure the electrical signal output from the radiation detector according to the radiation incident on the organic semiconductor, calculate the radiation intensity, which is the intensity of radiation from the measurement object, based on the measured electrical signal, and calculate A processing device for causing the display to display information representing the emitted radiation intensity,
The radiation measuring apparatus according to claim 1, further comprising: The radiation intensity is a dose rate of radiation from a measurement object,
The processing device is
A dose rate conversion coefficient indicating a relationship between an electrical signal from the radiation detector and a dose rate of radiation from the measurement target, a memory in which the dose rate conversion coefficient is stored in advance,
Based on the electrical signal from the radiation detector and the dose rate conversion factor, calculate the dose rate of radiation from the measurement target,
The radiation measurement apparatus according to claim 2, wherein information indicating the calculated dose rate of radiation from the measurement target is displayed on the display. The radiation intensity is the radioactivity to be measured,
The processing device is
A radioactivity conversion coefficient indicating the relationship between the electrical signal from the radiation detector and the radioactivity of the measurement object, and a memory in which is stored in advance;
Based on the electrical signal from the radiation detector and the radioactivity conversion coefficient, calculate the radioactivity of the measurement target,
The radiation measurement apparatus according to claim 2, wherein information indicating the calculated radioactivity of the measurement target is displayed on the display. At least one of the anode and the cathode is an electrode array in which a plurality of electrodes are arranged at intervals along the same surface of the organic semiconductor,
The indicator has a plurality of display areas,
The said processing device displays the radiation intensity calculated corresponding to each electrode which comprises the said electrode array on the display area corresponding to the said electrode, The any one of Claim 2 thru | or 4 characterized by the above-mentioned. The radiation measuring apparatus according to item. The radiation measuring apparatus according to claim 5, wherein each display region is arranged at a position facing the corresponding electrode in the thickness direction of the radiation detector. The indicator includes a plurality of light emitting elements arranged along the radiation detector,
The radiation measuring apparatus according to claim 5, wherein each display region includes at least one of the light emitting elements. The indicator is
An organic EL panel that is substantially sheet-like and flexible and includes the plurality of display areas;
The radiation measuring apparatus according to claim 5, wherein the organic EL panel is overlapped with and coupled to the radiation detector. The radiation detector has a substantially rectangular shape, is wide in the width direction and the longitudinal direction perpendicular to the thickness direction,
The radiation measuring apparatus according to claim 2, wherein the processing device is coupled to an edge of the radiation detector that extends in the width direction. The radiation detector is
A shield that is a conductor capable of shielding electromagnetic waves or light directed to the organic semiconductor on the measurement target side from the anode and the cathode,
The radiation measuring apparatus according to claim 1, further comprising: The radiation detector is
A substantially sheet-like substrate that is flexible and includes an electrical insulator;
11. The substrate, the single cathode, the single organic semiconductor, and the plurality of anodes are stacked in that order in the thickness direction of the radiation detector. The radiation measuring device according to any one of the above. The radiation detector is
A guard ring which is disposed on the organic semiconductor and which surrounds the anode with a space in a direction perpendicular to the thickness direction of the radiation detector and is electrically insulated from the anode and the cathode The
The radiation measuring apparatus according to claim 1, further comprising: The organic semiconductor includes a plurality of layers stacked between the anode and the cathode,
The radiation measuring apparatus according to claim 1, wherein at least one of the plurality of layers is a high-sensitivity layer having higher sensitivity to radiation than the others. The radiation measuring apparatus according to claim 13, wherein the high-sensitivity layer includes a base material mixed with a luminescent material that emits light upon receiving radiation. The radiation measuring apparatus according to claim 13, wherein the high-sensitivity layer includes a base material mixed with a nuclear reactant that reacts with neutrons.

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