JPS63215987A - Highly resolvable scintillation fiber plate - Google Patents

Abstract

PURPOSE:To prevent a luminous efficiency from being reduced by the deliquescence of a columnar crystal scintillator, improve its mechanical strength and facilitate handling by covering the scintillator by a film and fixedly supporting the scintillator. CONSTITUTION:A columnar crystal scintillator 1 formed on a fiber plate 3 is covered by an organic film 8 and fixedly supported. As the organic film 8, a xylene resin, for example, polyparaxylene, polymonochloroxylene or the like is used. A water vapor permeability is low due to the film formed by CVD (Chemical Vapor Deposition) method so that the scintillator 1 composed of columnar crystals is not brought into contact with are and an X-ray transmittance is high, being able to be used down to a low energy region. Further, in order to prevent a loss from being generated in the amount of emitted light by the phenomenon that the light emitted from the scintillator 1 returns to an input side and emitted outside therefrom, a reflecting mirror (or light absorbing film) 7 is coated on the outer or inner surface of the organic film 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a scintillation fiber plate for observing XM images with high resolution.

[Conventional technology]

Conventionally, a scintillation fiber plate for observing two-dimensional X-ray images (several KeV to 100 KeV) with high resolution has a columnar shape on a normal fiber plate with a diameter equal to the fiber diameter of the fiber plate, as shown in Figure 4. Crystals are arranged independently from each other with a slight distance between them.

In the figure, 1 is a scintillator, 2 is a Talarad glass, 3 is a fiber plate, 4 is a core glass, and 5 is an X-ray.

The fiber diameter of a normal fiber plate is 5 to 6 μm.
Therefore, the columnar crystal scintillator 1 is also of the same size. The material of the columnar crystals depends on the quality of the X-rays used, but
Usually Csr, NaI are used.

FIG. 5 is a diagram showing an example of use of the scintillation fiber plate shown in FIG. 4, and 6 is a sample.

For example, the X-ray image transmitted through the sample 6 and projected onto the plate is divided into segments consisting of the above-mentioned columnar crystals.
As shown in the figure, scintillation light is generated in each segment. A part of this scintillation light first propagates through the columnar crystal scintillator l while repeating reflection to the fiber plate 3 side, and then enters the fiber plate 3 while undergoing some reflection loss at the end of the fiber plate 3, and finally enters the fiber plate 3. Appears at the output end of plate 3. As shown in FIG. 4, this scintillation fiber plate exhibits extremely high spatial resolution because each columnar crystal and the corresponding fiber form segments independently.

[Problems to be solved by the invention]

Incidentally, scintillator materials used for the columnar crystal portions of scintillation fiber plates include Cs 1% Na I and the like as described above, but all of them have deliquescent properties. In the structure shown in the figure, each columnar crystal is very thin, less than 6 μm, and therefore,
The number of columnar crystals that make up the whole is enormous. For example, in the case of a diameter of 1 inch, the number of crystals is about 6 million.

As each crystal is independent and spatially separated, the surface area of the crystal is extremely large, approximately 40 times that of a 1-inch diameter single crystal. Therefore, when left in the air, deterioration of luminous efficiency due to deliquescence becomes a problem.

FIG. 6 is a diagram showing experimental results of changes in luminous efficiency over time in an inert gas and in the atmosphere.

In the figure, there is almost no change when stored in a nitrogen atmosphere as an inert gas, and 2% when stored in the atmosphere.
It can be seen that the temperature decreases to about 15% in 4 hours. This is because air enters between each columnar crystal, deliquifying the crystal and reducing luminous efficiency.

Therefore, the entire scintillator is completely covered with a film that is highly transparent to X-rays, completely blocking air, preventing not only deliquescent properties but also deterioration of luminous efficiency due to contact between air and the crystal surface, as well as improving handling. However, in the case of high-resolution scintillation fiber plates, each crystal is very thin, with a diameter of 6 μm or less and a length of several 100 μm to several 100 μm, and is therefore an aggregate of mechanically extremely weak crystals. Because of this, it is not possible to protect the columnar crystals by applying a coating with aluminum foil or by directly pressing the Be plate.Also, storage in a vacuum container has been proposed, but it is not possible to securely fix the tips of the columnar crystals. There was a problem with mechanical strength.

The present invention is intended to solve the above problems, and prevents a decrease in luminous efficiency due to the deliquescence of the scintillator, as well as
The purpose of the present invention is to provide a high-resolution scintillation fiber plate that has improved mechanical strength and can be easily handled.

[Means for solving problems]

To this end, the high-resolution scintillation fiber plate of the present invention has a three-fiber plate consisting of a fiber plate and a group of columnar crystal scintillators formed on one fiber plate, in which the columnar crystal scintillator is covered with a film and fixedly supported. It is characterized by

[Effect]

The high-resolution scintillation fiber plate of the present invention covers and fixes a columnar crystal scintillator group with a film, thereby shielding the scintillator from the air and preventing it from deliquescence, while applying stress toward the fiber plate substrate. The scintillator can be fixedly supported without any problems.

〔Example〕

An example will be described below with reference to FIG.

FIG. 1 is a diagram showing an embodiment of a high-resolution scintillation fiber plate according to the present invention, and the same numbers as in FIG. 3 indicate the same contents. In the figure, 7 is a reflective film coating, and 8 is an organic film.

In the figure, an organic film 8 is formed by CVD (Ch
e+wical Vapor Deposition
) method with high XSS permeability (,
It also consists of a coating that can block air.

In this case, film formation is performed in vacuum or in an inert gas to prevent air from entering the organic film 8. Note that the output surface of the plate is not coated with an organic film to obtain high resolution. By forming this film, it is possible to prevent deterioration of luminous efficiency due to deliquescence, which becomes a problem when the scintillation fiber plate is left in the air.

In addition, this organic film adheres to all scintillator tips that are not completely flush, so it can be fixed and supported without applying stress to the fiber plate substrate.
It also serves to improve the strength of extremely thin scintillators.

Note that as the organic film 8, for example, polyparaxylene,
Xylene-based resins such as polymonochloroxylene and polydichloroxylene are preferable, and a xylene-based resin film with a thickness of 10 μm has a very low water vapor permeability and
It has a high vA transmittance and can be used up to a low energy range of several hundred eV. However, in this case, since the organic film 8 is a transparent thin film, the light emitted by the scintillator 1 returns to the input side and is emitted from there to the outside, resulting in a loss in the amount of light emitted. Furthermore, light may be directly incident on the scintillation fiber plate. Therefore, it is desirable to coat the outer or inner surface of the organic film 8 with a reflective film 7 or the like to reflect the light back to the scintillator side, or to provide a light absorption film to block direct light from the outside.

Figure 2 is a diagram showing the CVD deposition method of xylene resin.
In the figure, 11 is a heating chamber, 12 is a decomposition furnace, 13 is a vapor deposition chamber, 1
4 is a cooling device.

In the figure, 150% of the xylene resin material is heated in the heating chamber 11.
The vapor is heated to about ~200°C to sublimate and evaporate, and then heated to about 550 to 700°C in the decomposition furnace 12 to be molecularized. The vapor in the molecularized state is vaporized by bringing the vapor deposition chamber 13 to room temperature. . Note that the cooling device 14 is provided to prevent molecules from going to the vacuum pump side.

FIG. 3 is a diagram showing a xylene-based resin film produced on a columnar crystal scintillator by the method shown in FIG. 2, and the same numbers as in FIG. 1 indicate the same contents.

The gaps between the scintillator columnar crystals are filled with an inert gas such as nitrogen or evacuated so that the refractive index is approximately 1. By doing this, Cs I, Na used as a scintillator
Since I has a refractive index of approximately 1.7, the scintillation light is reflected from the inner surface of the columnar crystal and reaches the fiber plate.

The xylene-based resin film deposited by the CVD method can withstand high vacuum, has an X-ray transmittance of almost 100%, and has extremely low permeability to air and vapor, so it prevents the deliquescence of the scintillator columnar crystals. In addition, since it has excellent flexibility and good dimensional stability, the tip of the scintillator columnar crystal can be stably fixed and supported.

Note that instead of directly vapor depositing xylene resin to form a film, the xylene resin film grown on a flat object such as a glass plate is peeled off, wrapped on a scintillation fiber plate, and the surrounding area is covered with adhesive. The same effect can be obtained even if the resin film is fixed with a similar method because the resin film has excellent flexibility.

In addition to xylene-based resin, aluminum or the like may also be vapor-deposited, but in this case, it is difficult to completely seal the gaps between columnar crystals compared to xylene-based resin, and air (moisture) is It is necessary to consider ease of passage.

〔Effect of the invention〕

As described above, according to the present invention, by covering and fixing the columnar crystal scintillator group with a film, the scintillator can be completely shielded from the air, and it is possible to prevent the luminous efficiency from decreasing due to deliquescence. In addition, all the scintillator columnar crystals can be fixedly supported without applying stress to the fiber plate, and as a result, the mechanical strength can be improved and handling becomes easier.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of a high-resolution scintillation fiber plate according to the present invention, Fig. 2 is a diagram showing a CVD deposition method of xylene-based resin, and Fig. 3 is a diagram showing a xylene-based resin produced on a columnar crystal scintillator. Figure 4 shows a resin film, Figure 4 is a cross-sectional view of a high-resolution scintillation fiber plate, Figure 5 shows an example of how a scintillation fiber plate is used, and Figure 6 shows luminous efficiency when stored in inert gas and in air. FIG. 1...Scintillator, 2...Tararad glass, 3.
...Fiber plate, 4...Core glass, 5...
・X&l. 6... Sample, 7... Reflective film coating, 8...
Organic film, 11... heating chamber, 12... decomposition furnace,
13... Vapor deposition chamber, 14... Cooling device. Applicant Hamamatsu Photonics Co., Ltd. Representative
Person Patent Attorney Masanobu Hirukawa Figure 1 Figure 2

Claims (3)

[Claims] (1) A high-resolution scintillation fiber plate comprising a fiber plate and a group of columnar crystal scintillators formed on the fiber plate, characterized in that the columnar crystal scintillator is covered with a film and fixedly supported. (2) The high-resolution scintillation fiber plate according to claim 1, wherein the film is made of xylene resin. (3) The high-resolution scintillation fiber plate according to claim 1, wherein the outer or inner surface of the film is coated with an absorbing film or a reflective film for blocking light.