JP6483530B2 - Installation material for scintillation counter - Google Patents

Description

  The present invention relates to an installation member for a scintillation counter, and more particularly to an installation member for a scintillation counter for installing a radioactive sample and a scintillator in a vial.

  The scintillation counter is a device that measures radiation (for example, β rays) emitted from a sample containing a radioactive substance. In the scintillation counter, a scintillator that emits light by the incidence of radiation is used, and the radiation emitted from the sample is measured by converting the light generated in the scintillator into an electrical signal.

  Conventionally, a liquid scintillation counter using a liquid scintillator is used as the scintillator. A liquid scintillation counter is a container transport unit that transports a sample container (vial) containing a sample and a liquid scintillator, a pair of photomultiplier tubes that convert light emitted from the liquid scintillator into an electrical signal, and a photomultiplier tube A measurement unit for measuring the converted electrical signal is included.

  However, in recent years, it has been proposed to use a plastic scintillator instead of the liquid scintillator because, for example, a radioactive waste liquid is generated after radiation measurement when the liquid scintillator is used. For example, in Patent Document 1, a sample (radioactive sample) is sandwiched between two plate-shaped plastic scintillators, and the sample is placed on a sample body installation portion provided between a pair of photomultiplier tubes to emit radiation. A scintillation counter for measuring is disclosed.

International Publication No. 2014/088046

  When measuring radiation emitted from a sample, a sandwich structure including a sample and a pair of plate-like plastic scintillators sandwiching the sample may be contained in a vial. For example, from the viewpoint of diverting existing equipment, in a conventional liquid scintillation counter, instead of a sample and a liquid scintillator, the sandwich structure may be housed in a vial and radiation may be measured.

  When the sandwich structure is accommodated in the vial, the detection efficiency of light in the photomultiplier tube differs depending on the position of the sandwich structure in the vial, so the position of the sandwich structure in the vial becomes a problem. When detecting light emitted from the scintillator, the vial is disposed between a pair of photomultiplier tubes, and a pair of photomultiplier tubes are located on both side surfaces of the vial. Therefore, a preferable detection efficiency can be obtained when the sandwich structure is in a vertical posture in the vial. On the other hand, when the sandwich structure changes its posture in the vial and is largely inclined from the vertical posture, the light detection efficiency in the photomultiplier tube is lowered. As the light detection efficiency decreases, there is a problem that accurate measurement cannot be performed, for example, the measurement value becomes smaller than the radiation dose emitted by the sample.

  In addition, when performing radiation measurements on multiple sandwich structures in multiple vials, light detection is performed for each sandwich structure if the position of each sandwich structure varies within each vial. Efficiency will be different. That is, there arises a problem that radiation measurement cannot be performed under the same conditions for each sandwich structure.

  An object of the present invention is to hold a sandwich structure composed of a radioactive sample and a pair of plate scintillators sandwiching the radioactive sample in a vertical position in a vial. Alternatively, an object of the present invention is to suppress changes in the posture of the sandwich structure in the vial.

  The present invention is a scintillation counter installation member for installing a sandwich structure consisting of a radioactive sample and a pair of plate scintillators sandwiching the radioactive sample in a vial set in the scintillation counter, A holder for holding and maintaining the sandwiched state of the radioactive sample by the pair of plate scintillators, and the sandwich structure mounted on the inner bottom surface of the vial in the installed state in which the sandwich structure is installed. A pedestal that holds the holder so that the body stands vertically, and in the installed state, the upper end of the holder is located inside the neck of the vial, and the sandwich structure is inclined from the vertical state. When the posture changes to Regulating the posture change by contact to the surface, characterized in that.

  According to the above configuration, the sandwich structure is held by the holder, and the pedestal holding the holder is placed on the inner bottom surface of the vial (that is, the pedestal (and the holder and the sandwich structure) are dropped into the vial). ) So that the sandwich structure is held in a vertical position in the vial. The vertical posture of the sandwich structure is a posture in which the contact surfaces of the pair of plate scintillators with the radioactive sample are parallel to the vertical direction. Since the pedestal (and the holder and the sandwich structure) is dropped into the vial, the size of the pedestal or the like is set to a size that can pass through the neck portion. On the other hand, the neck of the vial is narrowed with respect to the body, that is, the horizontal sectional area of the body is larger than that of the neck. Therefore, a gap is inevitably generated between the pedestal dropped into the vial and the inner surface of the body part. As a result, the pedestal dropped into the vial may be moved or inclined in the vial due to the influence of vibration transmitted from the bottom surface of the vial. Therefore, in the above configuration, the upper end of the holder is positioned inside the neck portion of the vial in the installed state, so that even if the pedestal moves or tilts in the vial, the upper end of the holder that moves or tilts accordingly. By abutting on the inner surface of the neck portion, movement or inclination of the holder and the pedestal is suppressed. Thereby, the posture change in the vial of the sandwich structure is suppressed.

  Preferably, the pedestal is formed of an elastic material that exhibits an elastic holding action of the holder and an absorption action of vibration transmitted from the inner bottom surface. This makes it difficult for the pedestal and the holder in the vial to be moved or inclined by vibration from the bottom surface of the vial.

  Preferably, the pedestal has a size passing through the neck portion of the vial, and the pedestal has a top surface having an upper opening of a vertical groove into which a lower end portion of the holder is inserted, and a horizontal surface in contact with the inner bottom surface. It has a lower surface.

  Since the lower surface of the pedestal is horizontal, the pedestal is placed horizontally on the bottom surface of the vial that is a horizontal surface. Further, since the vertical groove is formed on the upper surface of the pedestal, the holder inserted into the vertical groove is erected in the vertical direction. As a result, the sandwich structure held by the holder is also erected vertically.

  Preferably, the holder has a flat plate shape, and has a vertical slit extending downward from the upper surface of the holder in the installed state, and the sandwich structure is inserted into the vertical slit. Alternatively, preferably, the holder has a flat plate shape and has a horizontal slit extending in a horizontal direction from a side surface of the holder in the installed state, and the sandwich structure is inserted into the horizontal slit.

  By providing a slit for inserting the sandwich structure in the holder, the sandwich structure can be easily held in the holder. In particular, by providing the vertical slit, the sandwich structure can be taken in and out of the vertical slit while the base and the holder are installed in the vial.

  Further, the present invention is a scintillation counter installation member for installing a sandwich structure comprising a radioactive sample and a pair of plate scintillators sandwiching the radioactive sample in a vial set in the scintillation counter, the sandwich structure A suspension holding part that holds the upper end of the body and holds the sandwich structure in a suspended state in the vial is provided.

  When the sandwich structure is suspended and held in the vial by the suspension holding portion, the vertical posture of the sandwich structure is maintained by the action of gravity. Further, since the sandwich structure is not in contact with the inner bottom surface or the inner side surface of the vial by being suspended, it is not affected by vibrations transmitted from at least these surfaces. Therefore, the sandwich structure is more difficult to move or tilt by being held suspended.

  Desirably, the suspension holding part has a flange projecting in the horizontal direction, and the flange is sandwiched between an upper edge of the vial body and a ceiling surface of the cap of the vial.

  A flange is provided in the suspension holding portion so as to be hooked on the upper edge of the vial body, thereby preventing the suspension holding portion and the sandwich structure held by the suspension holding portion from falling into the vial body. Furthermore, the hanging holding part is fixed to the vial by the flange being sandwiched between the upper edge of the vial body and the ceiling surface of the cap of the vial. Thereby, since the movement of the suspension holding part in the vial is suppressed, a change in the posture of the sandwich structure is suppressed. Moreover, since the suspension holding part is fixed with the tightening operation of the cap, an increase in work amount for fixing the suspension holding part is suppressed.

  Preferably, the suspension holding part is formed integrally with the cap of the vial. Thereby, the sandwich structure is suspended and held in the vial in accordance with the operation of attaching the cap to the vial body. Moreover, since the suspension holding part is integrated with the cap and the suspension holding part does not move or tilt in the vial, a change in the posture of the sandwich structure is suppressed.

  Preferably, the sandwich structure further includes a lower end holding member that holds the lower end of the sandwich structure. By sandwiching not only the upper end portion but also the lower end portion of the sandwich structure, the pair of plate scintillators of the sandwich structure are prevented from opening at the lower end portion. Furthermore, it functions as a weight of the sandwich structure in which the lower end portion clamping member is suspended and held, and thereby the posture change of the sandwich structure can be further suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the sandwich structure which consists of a radioactive sample and a pair of plate scintillator which pinches | interposes it in a vial can be hold | maintained to a perpendicular | vertical attitude | position. Or according to this invention, the attitude | position change of the sandwich structure in a vial can be suppressed.

It is a figure which shows the outline | summary of the scintillation counter which concerns on this embodiment. It is a top view of the scintillation counter which concerns on this embodiment. It is the perspective view and side view of a sandwich structure. It is a perspective view of the sample unit in a 1st embodiment. It is the front view and side view of the installation state of the sample unit in 1st Embodiment. It is the front view and side view of the inclination state of the sample unit in a vial. It is a perspective view of the sample unit in 2nd Embodiment. It is the front view and side view of the installation state of the sample unit in 2nd Embodiment. It is a perspective view of the sample unit in 3rd Embodiment. It is the front view and side view of the installation state of the sample unit in 3rd Embodiment. It is a perspective view of the sample unit in 4th Embodiment. It is the front view and side view of the installation state of the sample unit in 4th Embodiment.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

<Outline of scintillation counter>
FIG. 1 is a schematic diagram showing the overall configuration of a scintillation counter 10 according to the present embodiment. The scintillation counter 10 measures a radioactive substance contained in a sample using a plastic scintillator. In FIG. 1, the X direction is the first horizontal direction, the Y direction is the second horizontal direction, and the Z direction is the vertical direction.

  The scintillation counter 10 includes a transport table 12 having a transport surface that extends in the X direction and the Y direction. A plurality of racks 14 are transported on the transport table 12. In the present embodiment, a Y transport path 16, an X transport path 20, a Y transport path 18, and another X transport path are provided on the transport table 12. The transport mechanism 16 </ b> A is a mechanism for transporting the rack 14 in the forward direction in the Y direction on the Y transport path 16. The transport mechanism 18A is a mechanism for transporting the rack 14 in the reverse direction in the Y direction on the Y transport path 18. A mechanism for transporting the rack 14 forward in the X direction on the X transport path 20 is not shown in FIG. Similarly, a mechanism for transporting the rack 14 in the opposite direction in the X direction on another X transport path is not shown in FIG.

  The rack 14 has a longitudinal direction and a short direction. The longitudinal direction is the direction in which the plurality of accommodating portions 27 are arranged. The short direction is a direction orthogonal to the long direction. In each accommodating part 27, the vial 22 which is a sample container is held. The vial 22 includes a vial body 24 and a cap 26. The vial 22 contains a sample containing a radioactive substance and a plastic scintillator for measuring radiation from the sample. Generally, a plastic scintillator is a substance that emits light upon receiving radiation (β rays in the present embodiment).

  In the present embodiment, an adapter is attached to each rack 27 with respect to the rack body. An opening / closing mechanism 28 is realized as a function of the adapter. That is, the rack 14 has a plurality of opening / closing mechanisms 28 corresponding to the plurality of accommodating portions 27. Each open / close mechanism 28 takes a closed state and an open state, holds the vial 22 in the closed state, and releases the vial 22 by releasing the holding of the vial 22 in the open state. In the present embodiment, the vial 22 to be measured is pulled out from the rack 14 downward.

  On the X transport path 20 in the transport table 12, a guide block 30 is fixedly installed at a place where the target container is taken in and out. The guide block 30 is a member that enters the lower portion of the rack 14, and specifically, a member that enters between a pair of legs of the rack 14 and applies an opening force to each opening / closing mechanism 28. . Moreover, it is a member for optimizing the position and posture of the rack in cooperation with the pressing unit 32 described later. The guide block 30 has an opening penetrating in the vertical direction at the center thereof, and the opening corresponds to the upper end portion of the hoistway 29. The hoistway 29 is a passage through which the sample container to be measured moves up and down between the rack 14 and the sample measurement chamber 34. In the present embodiment, the guide block 30 is positioned with high accuracy with respect to such a hoistway 29. In other words, the guide block 30 is physically integrated with the structure constituting the hoistway 29.

  In the present embodiment, a pressing unit 32 is provided in order to optimize the position and posture of the rack 14 when each sample container is taken in and out. The pressing unit 32 exerts a pressing force on the outer surface of one of the pair of legs of the rack 14, and thereby, the one of the legs is against the reference surface of the guide block 30. The inner surface is closely attached. By forming such a close contact state, the position and posture of the rack 14 are optimized.

  When measuring the radiation emitted from the sample, a sample container 36 to be measured is accommodated in the sample measurement chamber 34. An elevating mechanism 40 is provided to elevate and lower the sample container 36. The sample container 36 can be moved up and down in the hoistway 29 by the elevating mechanism 40.

  In the present embodiment, the elevating mechanism 40 includes a shaft 43, a head 44 provided at the upper end portion thereof, a slide mechanism 46 that drives the shaft 43, and the like. When the sample container is transferred between the rack 14 and the head 44, the head 44 is inserted into the opening of the guide block 30. In such a state, the opening / closing mechanism 28 provided in the accommodating portion 27 positioned immediately above the opening is in an open state. Specifically, in the process of transporting the rack 14, the open / close mechanism 28 comes into contact with the guide block 30, and the open / close mechanism 28 receives a horizontal opening force from the guide block 30, thereby forming the open state of the open / close mechanism 28.

  The sample measurement chamber 34 is mounted on the base 48. When light emission occurs in the sample container 36 accommodated in the sample measurement chamber 34, the light is detected by a pair of photomultiplier tubes 38. A pair of photomultiplier tubes 38 are provided to execute a so-called coincidence process. In the present embodiment, a special light shielding structure 50 is provided below the sample measurement chamber 34. The light blocking structure 50 prevents extraneous light from entering the sample measurement chamber 34 through the surface of the shaft 43. The light shielding structure 50 is provided across the lower surface of the head 44 and the upper surface of the base 48 with which the lower surface contacts. A predetermined light shielding structure is also provided in the head 44. A shutter mechanism 42 is provided on the hoistway 29 so as to cross it. The shutter mechanism 42 in the present embodiment includes an upper shutter mechanism and a lower shutter mechanism, that is, a double shutter mechanism is realized. The upper shutter mechanism is a mechanism for inserting a radiation shielding member on the upper side of the sample measurement chamber 34 in order to shield extraneous radiation, and the lower shutter mechanism is a hoistway to prevent entry of extraneous light from above. 29 is a mechanism for inserting a light shielding plate so as to cross 29.

  In the scintillation counter 10 according to the present embodiment, the rack 14 is intermittently sent in the X direction on the X transport path 20 with a posture in which the longitudinal direction is aligned with the X direction. In that case, the guide block 30 enters the lower part of the rack 14, and the opening / closing mechanisms 28 provided in the respective accommodating portions 27 are operated in order. The rack 14 is stopped in a state where the center line of each accommodating portion 27 and the center line of the hoistway 29 coincide. In this state, the sample container before measurement is sent from the rack 14 into the sample measurement chamber 34. After the measurement is completed, the sample container 36 after the measurement is returned to the original sample container accommodating portion. Thereafter, as the rack 14 is transported, the opening / closing mechanism 28 returns from the open state to the closed state in the accommodating portion 27 that has received the sample container. Such a series of processes is repeatedly executed for each storage unit 27.

  FIG. 2 is a top view of the sample measuring apparatus shown in FIG. As already described, the rack 14 is transported in the horizontal direction on the transport table 12. In this embodiment, a Y transport path 16, an X transport path 20, a Y transport path 18, and an X transport path 51 are provided as transport paths for the rack 14. A large number of racks 14 are usually arranged on the transport table 12, and each rack 14 is transported in order on each transport path.

  The center position in the X transport path 20 is a reference position for taking in and out the sample container. The guide block 30 is provided so that the center of the guide block 30 coincides with the reference position. In the vicinity of the guide block 30, a pressing unit 32 that exerts a pressing action on the rack 14 is provided. On the X transport path 20, the rack 14 is transported in the X direction by the transport mechanism 52 so that the longitudinal direction of the rack 14 is parallel to the X direction. The transport mechanism 52 has a claw member 54. The claw member 54 is moved in the X direction while hooking the tip of the claw member 54 against the protruding portion of the rack 14. Thereby, the rack 14 is conveyed in the X direction. The claw member 54 is configured so as not to hinder the operation of each opening / closing mechanism even in a state where the tip end portion is engaged with the rack 14.

  A transport mechanism 56 is also provided in the opposite X transport path 51 to transport the rack 14 in the X direction. The transport mechanism 56 has basically the same configuration as the transport mechanism 52. A member corresponding to the guide block 30 is not provided on the X transport path 51, but a pressing unit having the same configuration as the pressing unit 32 is disposed.

<First Embodiment>
Hereinafter, a first installation mode (first embodiment) of the sample and the plastic scintillator in the vial 22 will be described with reference to FIGS.

  FIG. 3 is a diagram showing a positional relationship between the sample and the plastic scintillator accommodated in the vial 22. As shown in FIG. 3A, the plate-like plastic scintillators 60A and 60B are brought into close contact with a sample 62 containing a radioactive substance interposed therebetween. As a result, a sandwich structure 64 in which the sample 62 is sandwiched between a pair of plastic scintillators 60A and 60B as shown in FIG. 3B is formed. The plastic scintillators 60A and 60B are transparent or milky white so as not to affect the generated light as much as possible. In the present specification, for convenience, one wide surface 64A of the sandwich structure 64 is referred to as “front surface” and the other wide surface 64B as “back surface”. Further, since the thickness of the sample 62 is extremely small, the sandwich structure 64 can be regarded as a rectangular parallelepiped. Therefore, the surface other than the front surface and the back surface (for example, the surface 64C) is described as “side surface” for convenience.

  FIG. 4A is a perspective view of the sample unit 66 accommodated in the vial 22 in the present embodiment. In the present embodiment, the sample unit 66 is formed by combining the sandwich structure 64, the holder 68, and the pedestal 70. Hereinafter, each member constituting the sample unit 66 will be described.

  The holder 68 holds the sandwich structure 64 so that the pair of plastic scintillators 60A and 60B (see FIG. 3) are not separated or displaced. Thereby, the sandwiched state 64 maintains the sandwiched state of the sample 62 by the pair of plastic scintillators 60A and 60B. Specifically, the holder 68 holds the front and back surfaces of the sandwich structure 64 so that the pair of plastic scintillators 60A and 60B are not separated. In order to prevent the plastic scintillators 60A and 60B from slipping, the holder 68 holds the side surfaces of the sandwich structure 64 so as to straddle the plastic scintillators 60A and 60B.

  The holder 68 is made of resin. The color of the holder 68 is transparent or milky white so as not to affect the light generated in the plastic scintillators 60A and 60B as much as possible.

  In the present embodiment, the outer shape of the holder 68 is a plate shape (cuboid shape). The holder 68 has a shape that extends vertically when the sample unit is housed in the vial 22 (installed state). In the holder 68, an opening is provided in the upper surface 68A in the installed state, and a slit 68B is formed extending vertically downward therefrom. The sandwich structure 64 is held by the holder 68 by being inserted into the slit 68B. The depth of the slit 68B is set to a depth at which the upper end of the sandwich structure 64 slightly protrudes from the upper surface 68A in a state where the sandwich structure 64 is inserted to the innermost part of the slit 68B. Thereby, as will be described later, the user can easily take out the sandwich structure 64 from the slit 68B.

  The pedestal 70 is a member for holding the holder 68. By holding the holder 68 on the base 70, the sandwich structure 64 is erected vertically in the vial 22. In the present embodiment, the pedestal 70 has a cylindrical shape. Of course, the pedestal 70 is not limited to a cylindrical shape, and may be a rectangular parallelepiped shape. Both the upper surface 70A and the lower surface 70B of the pedestal 70 are parallel to the horizontal plane in the installed state. The pedestal 70 is provided with an opening on the upper surface 70A and a vertical groove 70C extending vertically downward therefrom. And the base 70 hold | maintains the holder 68 by the lower end part of the holder 68 being inserted in the said vertical groove | channel 70C. The pedestal 70 is made of an elastic material such as rubber. Thereby, the holder 68 inserted into the vertical groove 70C can be suitably held. Further, since the pedestal 70 is formed of an elastic material, as described later, when the sample unit 66 is accommodated in the vial 22, there is also an effect that vibration from the inner bottom surface of the vial 22 is absorbed.

  When the sample unit 66 is formed, the sample unit 66 is accommodated in the vial 22 as shown in FIG. Specifically, the sample unit 66 is dropped into the vial body 24 from the vial opening 24A with the pedestal 70 facing downward, and the cap 26 is put on. In the present embodiment, the vial 22 has a cylindrical shape, but may have other shapes as long as it has a cylindrical shape.

  FIG. 5 shows the sandwich structure 64 installed in the vial 22. FIG. 5A shows a cross section of the vial 22 and a front view of the sample unit 66, and FIG. 5B shows a cross section of the vial 22 and a side view of the sample unit 66.

  As shown in FIGS. 5A and 5B, the vial body 24 has a neck portion 24B that is a tapered portion near the vial opening 24A, and a body portion 24C that has a larger horizontal cross-sectional area than the neck portion 24B. . Since the sample unit 66 is dropped into the vial body 24 through the neck portion 24B, the sample unit 66 is set to a size (width) that can pass through the neck portion 24B. In the installed state, the upper end portion of the sandwich structure 64 reaches the vicinity of the vial opening 24A, and the upper end portion of the holder 68 also reaches the inside of the neck portion 24B. As described above, since the opening of the slit 68B is provided on the upper surface 68A of the holder 68 (see FIG. 4A), the sandwich structure 64 is mounted while the pedestal 70 and the holder 68 are installed in the vial body 24. The holder 68 can be easily inserted and removed.

  When the sample unit 66 is dropped into the vial body 24, the horizontal lower surface 70B of the base 70 and the horizontal inner bottom surface 24D of the vial body 24 come into contact with each other. In this state, since the plate-shaped holder 68 is inserted into the vertical groove 70 </ b> C provided in the pedestal 70, the holder 68 is erected in the vertical direction. Since the sandwich structure 64 is inserted into the slit 68B provided vertically in the holder 68, the sandwich structure 64 is also erected vertically.

  As described above, since the horizontal sectional area of the body portion 24C is larger than that of the neck portion 24B, the sample unit 66 is dropped into the vial body 24 as shown in FIGS. 5 (a) and 5 (b). In such a state, a gap is inevitably generated between the side surface 70D of the base 70 and the inner side surface 24E of the vial body 24. For this purpose, the sample unit 66 can move or tilt in the vial body 24 by, for example, vibration transmitted from the inner bottom surface 24D.

  In this respect, since the pedestal 70 is formed of an elastic member as described above, vibrations from the inner bottom surface 24D are absorbed there. Thereby, the amount of vibration of the sample unit 66 due to vibration from the inner bottom surface 24D is reduced, and the movement or inclination of the sample unit 66 is suppressed. In order to further reduce the amount of vibration of the sample unit 66 due to vibration from the inner bottom surface 24D, the lower surface 70B of the pedestal 70 may be subjected to processing (roughening or the like) for improving the friction coefficient. Further, the area of the lower surface 70B (that is, the contact area with the inner bottom surface 24D) is preferably as large as possible as long as it can pass through the neck portion 24B.

  FIG. 6 shows the sample unit 66 in an inclined state in the vial 22. 6A is a front view of the sample unit 66 when tilted in the lateral direction (short direction of the holder 68), and FIG. 6B is when tilted in the front-rear direction (thickness direction of the holder 68). A side view of the sample unit 66 is shown.

  Although the amount of vibration of the sample unit 66 due to vibration from the inner bottom surface 24 </ b> D is reduced by the pedestal 70, the sample unit 66 may move or tilt in the vial body 24 due to receiving stronger vibration. In such a case, the movement or inclination of the sample unit 66 is suppressed by the holder 68 coming into contact with the inner surface of the vial. Specifically, in the installed state, since the upper end portion of the holder 68 is positioned inside the neck portion 24B, when the sample unit 66 is inclined in the lateral direction, as shown in FIG. The upper end of the sample unit 66 abuts against the inner side surface 24F of the neck portion 24B, so that further inclination of the sample unit 66 is prevented. Similarly, when the sample unit 66 is inclined in the front-rear direction, as shown in FIG. 6B, the upper end portion of the holder 68 abuts on the inner side surface 24F of the neck portion 24B. Tilt is prevented. FIG. 6 shows the inclination in the lateral direction and the front-rear direction. Similarly, even when the sample unit 66 is inclined in the other direction, the upper end of the holder 68 similarly contacts the inner surface 24F of the neck portion 24B. By contacting, the inclination of the sample unit 66 is suppressed. The same applies when the sample unit 66 moves.

Second Embodiment
Hereinafter, the 2nd installation form (2nd Embodiment) of the sample in the vial 22 and a plastic scintillator is demonstrated using FIGS. In the description of the second embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Also in the second embodiment, the sandwich structure 64 shown in FIG. 3 is installed in the vial 22.

  Fig.7 (a) is a perspective view of the sample unit 72 accommodated in the vial 22 in this embodiment. In the second embodiment, the shape of the holder is different from that of the first embodiment. In the present embodiment, a sample unit 72 is formed by combining the sandwich structure 64, the holder 74, and the pedestal 70, and the sample unit 72 is accommodated in the vial 22 as shown in FIG. 7B. The cap 26 is put on.

  The basic function or material of the holder 74 is the same as that of the holder 68 in the first embodiment. The holder 74 is also plate-shaped (cuboid), and has a shape extending in the vertical direction in the installed state. In the holder 74, an opening is provided in the side surface 74A in the installed state, and a slit 74B extending in the horizontal direction therefrom is formed. The holder 74 holds the sandwich structure 64 by inserting the sandwich structure 64 into the slit 74B. Notches 74 </ b> C are provided on the two wide surfaces of the holder 74. Thereby, a part of the sandwich structure 64 is exposed in the holding state by the holder 74, and the generated light in the plastic scintillator is more preferably detected by the photomultiplier tube.

  FIG. 8 shows a state in which the sandwich structure 64 is installed in the vial 22. 8A shows a cross section of the vial 22 and a front view of the sample unit 72, and FIG. 8B shows a cross section of the vial 22 and a side view of the sample unit 72.

  Also in the second embodiment, as in the first embodiment, when the holder 74 is erected vertically, the sandwich structure 64 is also erected vertically. In the installed state, the holder 74 inserted into the vertical groove 70 </ b> C of the pedestal 70 extends or extends to the inner portion of the neck portion 24 </ b> B of the vial body 24, so that the sample unit 72 moves or tilts. At the same time, the movement or inclination of the sample unit 72 is suppressed by the upper end portion of the holder 74 coming into contact with the inner side surface 24F of the neck portion 24B, as in the first embodiment.

<Third Embodiment>
Hereinafter, a third installation mode (third embodiment) of the sample and the plastic scintillator in the vial 22 will be described with reference to FIGS. In the description of the third embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Also in the third embodiment, the sandwich structure 64 shown in FIG. 3 is installed in the vial 22.

  FIG. 9A is a perspective view of a sample unit 80 for installing the sandwich structure 64 in the vial 22 in the present embodiment. In this embodiment, the sandwich structure 64, the clips 82 and 84, and the suspender 86 are combined to form the sample unit 80, and the sample unit 80 is set in the vial body 24, so that the sandwich structure 64 is formed. It is installed in the vial 22. Hereinafter, each member constituting the sample unit 80 will be described.

  Similar to the holder 68 in the first embodiment, the clips 82 and 84 hold the sandwich structure 64 so that the pair of plastic scintillators 60A and 60B (see FIG. 3) are not separated or displaced. Thereby, the sandwiched state 64 maintains the sandwiched state of the sample 62 by the pair of plastic scintillators 60A and 60B. Specifically, the clip 82 is provided with an opening on the lower surface thereof and a vertical groove 82A extending vertically upward therefrom, and the upper end portion of the sandwich structure 64 is inserted into the vertical groove 82A. Similarly, the clip 84 is provided with an opening on the upper surface and a vertical groove 84A extending vertically downward therefrom, and the lower end portion of the sandwich structure 64 is inserted into the vertical groove 84A. Thereby, the front surface and the back surface of the sandwich structure 64 are held at the upper and lower ends, and the upper and lower two side surfaces of the sandwich structure 64 are held. In this embodiment, two clips are provided. In the sandwich structure 64, when the pair of plastic scintillators 60A and 60B are connected on the lower side surface, the end of the sandwich structure 64 is used. Only one clip that holds the part may be provided.

  The clips 82 and 84 are formed of an elastic resin such as silicone rubber so that the sandwich structure 64 can be suitably held. The colors of the clips 82 and 84 are transparent or milky white so as not to affect the light generated in the plastic scintillators 60A and 60B as much as possible. In the present embodiment, the clips 82 and 84 have a rectangular parallelepiped shape, but may have other shapes.

  The suspender 86 is a member for suspending and holding the sandwich structure 64 in the vial 22 by further holding a clip 82 that holds the upper end of the sandwich structure 64. That is, the clip 82 and the suspender 86 constitute a suspension holding unit that holds the sandwich structure 64 in a suspended manner.

  The suspender 86 has a cylindrical base 86A. The horizontal cross-sectional shape of the base 86A is a shape corresponding to the shape of the neck 24B (see FIG. 10) of the vial, and is just large enough to fit inside the neck 24B of the vial body 24. In the present embodiment, the base portion 86A has a cylindrical shape, but may have other shapes according to the shape of the neck portion 24B. A vertical through hole 86B penetrating in the vertical direction is formed in the base portion 86A. By inserting the clip 82 into the vertical through hole 86 </ b> B, the clip 82 is held by the suspender 86. Therefore, the horizontal cross-sectional shape of the vertical through-hole 86 </ b> B is a shape corresponding to the horizontal cross-sectional shape of the clip 82. The suspender 86 has a flange portion 86C that protrudes to the side of the base portion 86A, that is, in the horizontal direction.

  When the sandwich structure 64, the clips 82 and 84, and the suspender 86 are combined to form the sample unit 80, the sample unit 80 is moved from the vial opening 24A into the vial body 24 as shown in FIG. Inserted. In the present embodiment, the sample unit 80 is not completely inserted into the vial body 24, the flange portion 86 </ b> C of the suspender 86 is hooked on the upper edge 24 </ b> G of the vial body 24, and the sample unit 80 is no longer in the vial body 24. It is not inserted into. In this state, the cap 26 is put on.

  FIG. 10 shows a state in which the sandwich structure 64 is installed in the vial 22. 10A shows a cross section of the vial 22 and a front view of the sample unit 80, and FIG. 10B shows a cross section of the vial 22 and a side view of the sample unit 80.

  As shown in FIGS. 10A and 10B, the flange portion 86C of the suspender 86 is hooked on the upper edge 24G of the vial body 24, so that the suspender 86 is hooked and held on the vial body 24. . The suspender 86 holds the clip 82 inserted into the vertical through-hole 86B, and the clip 82 holds the sandwich structure 64 inserted into the vertical groove 82A, so that the suspender 86 is hooked and held by the vial body 24. Accordingly, the sandwich structure 64 is suspended and held in the vial body 24 in a vertical posture.

  In such an installation state, since the flange portion 86 </ b> C of the suspender 86 is hooked on the upper edge 24 </ b> G of the vial body 24, the sample unit 80 does not fall on the vial body 24. Also, the base 86A of the suspender 86 is just inside the neck portion 24B, that is, the side surface of the base portion 86A and the inner side surface 24F of the neck portion 24B are in contact, so that the sample unit 80 moves in the horizontal direction. Or tilted. Further, the cap 26 is put on the suspender 86, and the flange portion 86C is sandwiched between the ceiling surface 26A of the cap 26 and the upper edge 24G of the vial body 24, whereby the sample unit 80 is fixed and moved. Or inclination is further suppressed. In particular, the vertical movement or inclination of the sample unit 80 is suppressed. Further, since the clip 84 is attached to the lower end portion of the sample unit 80, the clip 84 serves as a weight in the suspended holding state, and this acts to maintain the vertical posture of the sandwich structure 64. Furthermore, in the installed state, the lower end of the sample unit 80, that is, the lower end of the clip 84 is not in contact with the inner bottom surface 24D of the vial body 24, and therefore is not affected by vibration from the inner bottom surface 24D. Therefore, the sandwich structure 64 is stably maintained in the vertical posture in the vial 22.

<Fourth embodiment>
Hereinafter, a fourth installation mode (fourth embodiment) of the sample and the plastic scintillator in the vial 22 will be described with reference to FIGS. In the description of the fourth embodiment, the same members as those in the first and third embodiments are denoted by the same reference numerals, and the description thereof is omitted. Also in the fourth embodiment, the sandwich structure 64 shown in FIG. 3 is installed in the vial 22.

  FIG. 11A is a perspective view of a sample unit 90 for installing the sandwich structure 64 in the vial 22 in the present embodiment. In the present embodiment, the sample unit 90 is formed by combining the sandwich structure 64, the perforated clip 92, the clip 84, and the cap 94 of the vial 22, and the sample unit 90 is set in the vial body 24. The sandwich structure 64 is then installed in the vial 22.

  Like the clip 82 in the third embodiment, the perforated clip 92 is provided with an opening on its lower surface and a vertical groove 92A extending vertically upward therefrom, and the upper end of the sandwich structure 64 is provided in the vertical groove 92A. Part is inserted. Further, as in the third embodiment, the lower end portion of the sandwich structure 64 is inserted into the vertical groove 84 </ b> A of the clip 84. Thereby, the front surface and the back surface of the sandwich structure 64 are held at the upper and lower ends, and the upper and lower two sides of the sandwich structure 64 are held.

  The perforated clip 92 has an opening on its upper surface, and has a vertical hole 92B that extends vertically downward therefrom. This is a hole into which a convex portion provided on the ceiling surface of the cap 94 described later is inserted. The perforated clip 92 is also formed of an elastic resin such as silicon rubber, and the color thereof is transparent or milky white. In this embodiment, the perforated clip 92 has a cylindrical shape, but may have another shape such as a rectangular parallelepiped.

  The cap 94 is a lid of the vial 96. In the present embodiment, the cap 94 constitutes a part of the sample unit 90. FIG. 9B shows a cross-sectional view of the cap 94. As shown in FIG. 9B, the cap 94 has a top surface 94A and a wall portion 94B standing vertically downward from the outer edge of the top surface 94A, and has an inverted U-shaped cross section. In the present embodiment, the top surface 94A is circular in plan view, and the wall portion 94B is cylindrical along with it, but other shapes can also be adopted. The ceiling surface 94C of the cap 94 is provided with a protruding portion 94D that protrudes downward. The horizontal cross-sectional shape of the projecting portion 94D is a shape corresponding to the horizontal cross-sectional shape of the vertical hole 92B (see FIG. 9A) of the perforated clip 92. The protrusion 94D of the cap 94 is inserted into the vertical hole 92B of the hole clip 92, whereby the cap 94 and the hole clip 92 are integrated. In the present embodiment, the perforated clip 92 and the cap 94 constitute a suspension holding portion that holds the sandwich structure 64 in a suspended manner.

  When the sandwich structure 64, the perforated clip 92, the clip 84, and the cap 94 are combined to form the sample unit 90, as shown in FIG. 9B, the sample unit 90 is moved from the vial opening 24A to the vial body 24. The cap 94 is put on the vial body 24. The cap 94 is covered so that the inner side surface of the wall portion 94B faces the outer side surface of the neck portion 24B of the vial body 24.

  FIG. 12 shows a state where the sandwich structure 64 is installed in the vial 22. 12A shows a cross section of the vial 96 and a front view of the sample unit 90, and FIG. 12B shows a cross section of the vial 96 and a side view of the sample unit 90.

  12 (a) and 12 (b), the cap 94 and the perforated clip 92 are integrated, and the perforated clip 92 holds the sandwich structure 64 inserted into the vertical groove 92A. Therefore, when the cap 94 is put on the vial body 24, the sandwich structure 64 is suspended and held in the vial body 24 in a vertical posture.

  In such an installation state, the sample unit 90 is configured to include the cap 94, and the cap 94 is put on the vial body 24, so that the sample unit 90 does not fall onto the vial body 24. Further, if the cap 94 is fixed to the vial body 24, the sample unit 90 is fixed to the vial body 24, so that the vertical posture of the sandwich structure 64 is more suitably maintained. As in the third embodiment, the clip 84 attached at the lower end of the sample unit 90 acts to maintain the vertical posture of the sandwich structure 64. Further, as in the third embodiment, in the installed state, the lower end of the sample unit 90, that is, the lower end of the clip 84 is not in contact with the inner bottom surface 24D of the vial main body 24, and thus may be affected by vibration from the inner bottom surface 24D. Absent. Therefore, the sandwich structure 64 is stably maintained in the vertical posture in the vial 22.

  As mentioned above, although several embodiment which installs the sandwich structure 64 in the vial 22 or 96 was described, in any embodiment, the sandwich structure 64 is installed in the vertical position in the vial 22 or 96. In any of the embodiments, the posture change of the sandwich structure in the vial 22 or 96 is suppressed. Thereby, in the scintillation counter 10, the fall of the light detection efficiency in the photomultiplier tube 38 can be prevented. In addition, when performing radiation measurement on a plurality of sandwich structures, it is possible to reduce variations in measurement conditions for each sandwich structure. Of course, the above embodiment is merely an example, and various modifications can be made without departing from the spirit of the present invention.

  10 scintillation counters, 22, 96 vials, 24 vial bodies, 26, 94 caps, 60A, 60B plastic scintillators, 62 samples, 64 sandwich structures, 66, 72, 80, 90 sample units, 68, 74 holders, 70 pedestals, 82,84 clips, 86 suspenders, 92 perforated clips.

Claims (9)

A scintillation counter installation member for installing a sandwich structure comprising a radioactive sample and a pair of plate scintillators sandwiching the radioactive sample in a vial set in the scintillation counter,
A holder for holding the sandwich structure and maintaining the sandwiched state of the radioactive sample by the pair of plate scintillators;
A pedestal mounted on the inner bottom surface of the vial in an installed state in which the sandwich structure is installed in the vial, and holding the holder so that the sandwich structure stands vertically;
With
In the installed state, the upper end portion of the holder is positioned inside the neck portion of the vial, and the holder abuts on the inner surface of the neck portion when the sandwich structure changes its posture from the vertical state to the inclined state. To regulate the posture change,
A scintillation counter installation member. The pedestal is formed of an elastic material that exhibits an elastic holding action of the holder and an absorption action of vibration transmitted from the inner bottom surface.
The scintillation counter installation member according to claim 1, wherein the scintillation counter installation member is provided. The pedestal has a size that passes through the neck of the vial;
The pedestal has an upper surface having an upper opening of a vertical groove into which a lower end portion of the holder is inserted, and a horizontal lower surface in contact with the inner bottom surface,
The scintillation counter installation member according to claim 1, wherein the scintillation counter installation member is provided. The holder has a flat plate shape, and has a vertical slit extending downward from the holder upper surface in the installation state,
The sandwich structure is inserted into the longitudinal slit;
The installation member for a scintillation counter according to any one of claims 1 to 3, wherein the installation member is for a scintillation counter. The holder has a flat plate shape and has a horizontal slit extending in a horizontal direction from a side surface of the holder in the installation state,
The sandwich structure is inserted into the transverse slit;
The installation member for a scintillation counter according to any one of claims 1 to 3, wherein the installation member is for a scintillation counter. A scintillation counter installation member for installing a sandwich structure comprising a radioactive sample and a pair of plate scintillators sandwiching the radioactive sample in a vial set in the scintillation counter,
A suspension holding unit for holding the sandwich structure in a suspended state in the vial with the upper end of the sandwich structure sandwiched therebetween,
An installation member for a scintillation counter, comprising: The suspension holding part has a flange protruding in the horizontal direction,
The flange is sandwiched between the upper edge of the vial body and the ceiling surface of the vial cap,
The installation member for a scintillation counter according to claim 6, wherein: The hanging holding part is formed integrally with the cap of the vial,
The installation member for a scintillation counter according to claim 6, wherein: A lower end clamping member having a lower end of the sandwich structure;
The scintillation counter installation member according to any one of claims 6 to 8, further comprising: