JP2014145783A - Scintillator member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scintillator member capable of improving strength or adhesiveness of a light shield membrane and suppressing absorption of radioactive rays (α rays and β rays).SOLUTION: A scintillator member includes a scintillator 1 with a radioactive ray incident surface thereof being flattened, a light shield layer 7 directly formed on the radioactive ray incident surface of the scintillator 1, and a protective layer 9 formed on the light shield layer 7.

Description

  The present embodiment relates to a scintillator member using a scintillator.

  A plastic scintillator is a solid scintillator in which a phosphor (anthracene, stilbenebenzene, etc.) is dissolved in an organic solvent such as styrene or toluene to be polymerized (polystyrene, polyvinyltoluene, etc.).

  This plastic scintillator is easy to form into a thin film, long shape, etc., lightweight and flexible, so it has excellent impact resistance, low cost and high availability. Applied to various radiation detectors. In addition, since the specific gravity of the material is small and the γ-ray sensitivity is low, it is applied to a highly sensitive radiation detector for measuring β-rays.

  In a plastic scintillator, since the emitted fluorescence is weak, a photomultiplier tube is required for detection. For this reason, the case of the radiation detector has a structure in which outside light is blocked, and a plastic scintillator and a photomultiplier tube are housed therein, and the photomultiplier tube collects the fluorescence emitted by the plastic scintillator. It is arranged so that it can be detected.

  Further, the case is provided with a radiation incident window, and is arranged so that the surface of the plastic scintillator is in close contact with the surface of the radiation incident window. For the purpose of blocking external light while transmitting β-rays, a thin film window material, in which aluminum as a light-shielding material is vapor-deposited on one or both sides of a resin film such as polyester, is usually formed in a state where several sheets are stacked on the radiation incident window. The

  Further, in order to protect the window material when there is a possibility that the measurement target comes into contact with the window material, a lattice-shaped protection member having a high aperture ratio is provided on the upper surface of the radiation incident window.

  The window material is extremely fragile with respect to external force, and there is no constant damage accident including manufacturing and operation. In addition, pinholes, which are film-forming defects peculiar to vapor deposition, cannot be identified visually, and the presence of pinholes can only be found after receiving external light leaking into the case with a photomultiplier tube. Also, the production yield is bad. Moreover, although the window material which guaranteed the pinholelessness is also available, it is expensive and it is difficult to obtain a large-area window material.

  Therefore, in order to realize a physically strong light-shielding layer, a method of attaching a light-shielding film sheet in which an adhesive layer is interposed between the plastic scintillator surface and a light-shielding layer, a protective layer, etc. are laminated by thermal transfer or the like is considered ( Patent Document 1).

  By this method, the plastic scintillator and the light shielding film sheet are integrated by bonding, and a physically strong light shielding layer can be realized.

JP 2007-147581 A

  Fluorescence emitted in the plastic scintillator spreads uniformly at an isotropic angle. For example, in the case of a plate-shaped plastic scintillator, the fluorescence that totally propagates in the plastic scintillator at a critical angle caused by the refractive index difference from the air layer. There are components and fluorescent components emitted out of the plastic scintillator.

  The latter fluorescent component is reflected by the aluminum vapor deposition layer of the light shielding film, and most of the fluorescent component passes through the plastic scintillator and is emitted to the opposite side.

  However, as in Patent Document 1, when a light-shielding film sheet is attached to the surface of a plastic scintillator with an adhesive interposed, the adhesive layer absorbs fluorescence, which causes a reduction in the amount of collected light. In particular, it is considered that the adhesive layer needs to have a thickness of about several μm, and this is considered to be not negligible for inhibiting the transmission of radiation (α rays and β rays).

  In addition, titanium oxide powder is added to the adhesive layer in order to increase the reflectance, but the adhesive performance is degraded by the titanium oxide powder.

  Therefore, an object of the present embodiment is to provide a scintillator member that can improve the strength and adhesion of the light-shielding thin film and can suppress the absorption of radiation (α rays and β rays).

  In order to achieve the above-described object, the scintillator member of the present embodiment includes a scintillator in which a radiation incident surface is flattened, a light shielding layer directly formed on the radiation incident surface of the scintillator, and the light shielding layer. And a protective layer formed thereon.

  According to this Embodiment, while being able to improve the intensity | strength and adhesiveness of a light shielding thin film, the scintillator member which can suppress absorption of a radiation ((alpha) ray and (beta) ray) can be provided.

It is sectional drawing which shows one Embodiment of the surface planarization method of a scintillator, (a) is before grinding | polishing process, (b) is during grinding | polishing process, (c) shows the state after grinding | polishing process. The flowchart explaining the surface planarization method of the scintillator shown in FIG. Sectional drawing which shows one Embodiment of a scintillator member. The flowchart explaining the manufacturing method of the scintillator member of FIG. Sectional drawing which shows another embodiment of a scintillator member. Sectional drawing which shows another embodiment of a scintillator member. The flowchart explaining the manufacturing method of the scintillator member of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
(Scintillator surface flattening method)
FIG. 1 is a cross-sectional view showing an embodiment of a scintillator surface flattening method.

  FIG. 2 is a flowchart for explaining the surface flattening method of the scintillator shown in FIG.

  In the method of the present embodiment, first, as shown in FIG. 1A, a scintillator material obtained by bonding the scintillator 1 and the reinforcing material 2 is prepared (S1 in FIG. 2).

(Scintillator 1)
For example, a plastic base material scintillator 1 for β-ray detection is thinly processed to suppress the reaction probability of γ-rays, which are background line types, and has a thickness of approximately 0.1 mm to 0. 4 mm, desirably 0.2 mm. Since such a thinly processed plastic scintillator is fragile to external force, the strength of the scintillator 1 is ensured and flattened by joining and integrating the scintillator 1 and the reinforcing material 2.

(Reinforcing material 2)
The reinforcing material 2 is formed of, for example, a colorless and transparent acrylic resin so that the fluorescence emitted by the scintillator 1 can be transmitted, and the surface size is preferably the same as or slightly larger than that of the scintillator 1. When the surface size of the scintillator 1 is 600 mm × 300 mm, the reinforcing material 2 has a thickness of about 3 mm to 5 mm, and a necessary and sufficient strength can be obtained. If it is too thick, there is a possibility that the absorption of fluorescence increases and the sensitivity is lowered.

(Bonding of both)
For example, BC600 (Saint-Gobain Co., Ltd.), Aron Alpha (R) 201 (Toagosei Co., Ltd.), or the like can be applied as a bonding agent used for joining the scintillator 1 and the reinforcing material 2. The scintillator 1 is bonded to the reinforcing material 2 through this bonding agent. At this time, care should be taken not to mix excess adhesive, bubbles, or foreign matter into the adhesive layer. It is relatively easy to remove excess adhesive and air bubbles by placing a protective film such as polyethylene on the scintillator 1 and extruding it with a roller or the like.

(Protrusions 3 and scratches / holes 4)
Here, in the scintillator 1 as a product, as shown in FIG. 1A, a plurality of protrusions 3 that are considered to have adhered to the surface during the manufacturing process and that exceed several μm to 10 μm are formed. In some cases, a part of the surface is embedded.

  Even if a laminated thin film, which will be described later, is directly formed on the surface of the scintillator 1 in a state where such a projection 3 is still present, the projection 3 protrudes from the laminated thin film, and this becomes a pinhole, and light shielding cannot be established. Sometimes.

  Further, the scintillator 1 may have a plurality of pores 4 having a length of about several μm to several tens of μm and a depth of about several μm on the surface together with the protrusions 3. Even if the laminated thin film is directly formed on the surface of the scintillator 1 to be described later in the state where such scratches and holes 4 are still present, defects of the laminated thin film are generated, and this serves as a pinhole to maintain light shielding. There are things that cannot be done.

  Further, the protrusion 3 on the surface of the scintillator 1 cannot be removed by a simple cleaning process such as washing away the surface with pure water or a neutral detergent or blowing air. That is, even if a thin film can be directly formed on the surface of the scintillator 1 as it is, it is difficult to establish a light shielding film. For this reason, in this embodiment, as shown in FIG. 1B, the scintillator 1 is flattened.

(Flattening by polishing with abrasive)
As a method for flattening the scintillator 1, in this embodiment, the surface of the scintillator 1 is mechanically buffed (S2 in FIG. 2).

  When the scintillator 1 is a plastic scintillator, for example, as shown in FIG. 1B, the surface of the scintillator 1 is polished with a buff member 5 that hardly causes deep scratches on the surface of the scintillator 1, and a buff member 5. A rotating machine 6 for rotating and a polishing liquid (not shown) can be suitably used.

  The buff member 5 is preferably made of a sponge material that does not easily cause deep scratches on the surface of the scintillator 1, such as foam buffing pads 13258 and 13257 of Sumitomo 3M.

  In addition, it is desirable that the rotary machine 6 has a double action function for preventing continuous polishing of one part such as a buffing sander 9025 of Sumitomo 3M Co., because the surface of the scintillator 1 is not easily damaged. .

  In the polishing liquid, for example, 1 to 50 parts by weight of abrasive particles containing free abrasive grains having a particle diameter of 1 μm to 10 μm with respect to 100 parts by weight of water, such as polished extra fine of Sumitomo 3M Co., and non-silicon type A polishing liquid containing a lubricating liquid can be preferably used. The reason why the abrasive particle is 1 to 50 parts by weight is that if it is less than 1 part by weight, it takes too much time for polishing and the efficiency is deteriorated, and if it exceeds 50 parts by weight, the surface of the scintillator 1 may be scratched. .

  The abrasive particles are preferably soft particles such as plastic particles rather than hard particles such as alumina.

  Furthermore, the reason for using the non-silicon-based lubricating liquid is that when the silicon-based lubricating liquid is contained in the polishing liquid, the polishing liquid is repelled by the scintillator 1 and the polishing process cannot be performed well.

(Polishing process)
As a specific polishing processing procedure, first, the buff member 5 is attached to the rotating machine 6, and the abrasive is attached to the buff member 5 with about ² to 4 g per 100 cm ² , and the buff member 5 is attached to the surface of the scintillator 1. The surface of the scintillator 1 is polished by pressing lightly and operating the rotating machine 6.

  The standard for the buffing time is about 20 to 60 seconds per buff surface size. As a result, protrusions on the surface of the scintillator 1 can be efficiently removed, and deep scratches are unlikely to occur.

  Further, when it is difficult to remove the protrusions on the surface of the scintillator 1, for example, two types of buff members 5 having different hardnesses are prepared, and a hard buff (for example, a foam buffing pad 13258 of Sumitomo 3M Limited) is prepared first. It is preferable to perform polishing with a soft buff (for example, a foam buffing pad 13257 manufactured by Sumitomo 3M). This is more effective because scratches generated in the initial buffing process are not noticeable.

(Washing process)
After polishing, the abrasive grains contained in the polishing liquid may be in close contact with the surface of the scintillator 1, but if the abrasive grains remain, they become new projections. For this reason, in this Embodiment, the washing process using a neutral detergent is performed and an abrasive grain is removed (S3 of FIG. 2).

  The neutral detergent to be used preferably contains 0.5 to 1 wt% of a nonionic surfactant having no acid or alkalinity in consideration of physical properties on the scintillator 1. The reason why the content is 0.5 to 1 wt% is that if the amount is less than 0.5 wt%, the effect of using a nonionic surfactant hardly appears, and if it exceeds 1 wt%, the surface of the scintillator 1 is chemically changed. This is because there is a fear.

  As a specific cleaning procedure, first, the polishing liquid and the like are washed off while flowing pure water on the surface of the scintillator 1 after polishing.

  Next, by applying a neutral detergent to the surface of the scintillator 1 and allowing the entire surface to penetrate, the remaining abrasive grains are prevented from reattaching to the surface of the scintillator 1.

  Furthermore, while washing pure water again on the surface of the scintillator 1, washing is performed so that the components of the neutral detergent do not remain, and finally moisture is removed.

  By the above processing, a plurality of protrusions 3 existing on the surface of the plastic base material scintillator 1 can be removed safely and without deteriorating the characteristics of the scintillator 1, and scratches / holes 4 existing on the surface of the scintillator 1 can be removed. Can be less noticeable.

  Thereby, even if an aluminum layer having a thickness of, for example, about 0.25 μm is formed on the surface of the scintillator 1 by vapor deposition (sputtering or vacuum vapor deposition), the pinhole of the aluminum layer due to the protrusions is made zero or zero. Can be close.

  Further, for example, the plastic base material scintillator 1 may have a radiation layer (α ray or β ray) insensitive layer (several μm) in the surface layer depending on the manufacturing process. Since it can be removed, the detection efficiency of radiation (α rays and β rays) can be improved.

[Second Embodiment]
(First scintillator member using a flattened scintillator)
FIG. 3 is a cross-sectional view showing an embodiment of a scintillator member.

  The scintillator member 10 uses the scintillator material having a flattened surface described in the first embodiment, and is provided with a light shielding layer 7, an adhesive layer 8, and a protective layer 9 in this order.

  As the scintillator 1 and the reinforcing material 2 in the scintillator material, the same materials as those described in the first embodiment can be used.

(Light shielding layer 7)
The light shielding layer 7 can be formed of, for example, an aluminum layer formed by vapor deposition (such as sputtering or vacuum vapor deposition). The light shielding layer 7 must be made as low as possible (thin film thickness) from the need to suppress the absorption of radiation (α rays and β rays), but in the case of an aluminum layer, its thickness is 0.07 to 0. About 25 μm is preferable.

  Further, since the light shielding layer 7 is fragile to bumps and scratches, it is preferable to protect the light shielding layer 7 with a protective layer 9.

(Protective layer 9)
Since the protective layer 9 becomes a surface layer of the scintillator member and is usually exposed to the air, the dust in the air can be adsorbed by charging or the like, and the background can be increased due to the influence of the radon-based radioactive substance contained in the dust. There is concern about sex. Therefore, the protective layer 9 has a surface resistance value of 10 ¹⁰ Ω / sq. A conductive barrier film having the following is desirable. At this time, the protective layer 9 is preferably grounded.

  Furthermore, the protective layer 9 preferably enhances barrier properties against the transmission of moisture and the like in a high humidity environment in order to prevent deterioration of the light shielding layer 7 made of an aluminum layer or the like.

  From this point of view, the protective layer 9 is composed of a silicon-based silicon nitride film (SiNx), a silicon nitride oxide film (SiOxNx), a silicon oxide film (SiOx), a metal oxide-based magnesium oxide (MgOx), and aluminum oxide (AlOx). It is desirable to use a film mainly composed of an inorganic film such as

  On the other hand, the protective layer 9 may be affected by operations such as a person's crushing or scratching with a tip of a toe, a pencil, or a mechanical pencil apart from an accident during manufacture or operation. Conceivable.

  For example, when expressed in accordance with JIS K5600-5-4 (ISO / DIN 15184) scratch hardness (pencil method), the toe hardness of a person is generally said to be around 2H. It is used well. For this reason, destruction by the said factor can be suppressed by making the surface hardness of the protective layer 9 into 2H or more in pencil hardness.

(Manufacturing method of scintillator member 10)
FIG. 4 is a flowchart illustrating a method for manufacturing the scintillator member 10.

  As described in the first embodiment, the scintillator member 10 is obtained by flattening the surface of the scintillator 1 of the scintillator material in which the reinforcing material and the scintillator are bonded together by polishing and cleaning processes (S1 to S3). It can be manufactured by directly forming the light shielding layer 7 (S4) and further providing the protective layer 9 via the adhesive layer 8 (S5).

[Third Embodiment]
(Second scintillator member using flattened scintillator)
FIG. 5 is a cross-sectional view showing another embodiment of the scintillator member.

  The scintillator member 20 uses the scintillator material having a flattened surface described in the first embodiment, and is provided with a light shielding layer 7, an adhesive layer 8, and a protective layer 11 in this order.

  In the scintillator member 20, the thing similar to the scintillator member 10 of 2nd Embodiment can be used except the protective layer 11. FIG.

(Protective layer 11)
The protective layer 11 can be, for example, an aluminized mylar in which an aluminum thin film 13 is formed on the surface of the conductive resin film 12 as a barrier film and an antistatic film.

  In the aluminized mylar of the present embodiment, an example in which the aluminum thin film 13 is formed only on one side of the conductive resin film 12 and the aluminum thin film 13 side is bonded to the light shielding layer 7 is shown. Alternatively, an aluminum thin film 13 formed on both side surfaces of 12 may be used.

  Further, when a PET film having no conductivity is used instead of the conductive resin film 12, the aluminum thin film 13 formed on one surface thereof is not on the light shielding layer 7 side, but on the outside air side, contrary to FIG. What was formed in can be used.

  The scintillator member 20 can also be manufactured by the method shown in FIG.

[Fourth Embodiment]
(Third scintillator member using flattened scintillator)
FIG. 6 is a cross-sectional view showing still another embodiment of the scintillator member.

  In this scintillator member 30, a light shielding layer 7 is formed on the surface of the scintillator 1 whose surface has been flattened as described in the first embodiment, and further, a buffer layer 14, a barrier layer 15, and a conductive layer are further formed thereon. A protective layer 17 of a laminated thin film made of the resin layer 16 is formed.

  Although the buffer layer 14 is formed on the light shielding layer 7, it is preferable to contain a pigment | dye in order to improve light-shielding property.

  FIG. 7 is a flowchart illustrating a method for manufacturing the scintillator member 30.

  As described in the first embodiment, the scintillator member 30 flattens the surface of the scintillator 1 of the scintillator material in which the reinforcing material and the scintillator are bonded together by polishing and cleaning processes (S1 to S3), It can be manufactured by directly forming the light shielding layer 7 (S4) and further directly forming a protective layer comprising the buffer layer 14, the barrier layer 15, and the conductive resin layer 16 on the light shielding layer 7 (S6).

  Here, the buffer layer 14 is applied onto the light shielding layer 7 using, for example, a UV curable resin such as SUV-600 manufactured by Sanyu Rec Co., Ltd., dried, and then cured by irradiating with UV. Can be formed directly on top.

  Further, the conductive resin layer 16 as an antistatic film is also applied on the barrier layer 15 using a UV curable resin such as SUV-600 manufactured by Sanyu Rec Co., Ltd., dried, and then cured by irradiation with UV. Can be formed.

  As described above, in the second to fourth embodiments, by providing the protective layer 9, the protective layer 11, and the protective layer 17 on the light shielding layer 7, respectively, dust in the air is adsorbed by charging or the like. Therefore, the possibility that the background increases due to the influence of the radon-based radioactive substance contained in the dust can be reduced.

  Further, it is possible to improve the barrier property against the transmission of moisture or the like in a high humidity environment and prevent the light shielding layer 7 made of an aluminum layer or the like from being deteriorated.

  Furthermore, by securing the hardness of the protective layer 9, the protective layer 11 and the protective layer 17 to a pencil hardness of 2H or more, a toe, a pencil, and a mechanical pencil It is possible to prevent the light shielding layer 7 from being damaged by being pierced or scratched by the tip of the core.

DESCRIPTION OF SYMBOLS 1 ... Scintillator 2 ... Reinforcement material 3 ... Protrusion 4 ... Surface scratch / hole 5 ... Buff member 6 ... Rotating machine 7 ... Shading layer 8 ... Adhesive layer 9 ... Protective layer 10 ... Scintillator member 11 ... Protective layer 12 ... Conductivity Resin film 13 ... Aluminum thin film 14 ... Buffer layer 15 ... Barrier layer 16 ... Conductive resin layer 17 ... Protective layer 20 ... Scintillator member 30 ... Scintillator member

Claims (5)

A scintillator with a planarized incident surface of radiation;
A light shielding layer directly formed on the radiation incident surface of the scintillator;
A protective layer formed on the light shielding layer;
A scintillator member comprising: The protective layer has a surface resistance value of 10 ¹⁰ Ω / sq. The scintillator member according to claim 1, wherein the scintillator member is the following conductive film layer, which is formed on the light shielding layer via an adhesive.   The scintillator member according to claim 1, wherein the protective layer is formed by forming an aluminum thin film on one side or both sides of a resin film layer, and is formed on the light shielding layer via an adhesive. .   The scintillator member according to claim 1, wherein the protective layer is a laminated thin film including a buffer layer, a barrier layer, and a conductive resin layer in order from the light shielding layer side.   The scintillator member according to claim 4, wherein the buffer layer contains a dye, and the buffer layer and the conductive resin layer are made of UV curable resin.

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