JPH06181099A - Screen monitor of particle accelerator - Google Patents

Abstract

PURPOSE:To prevent the overheat and the melting of a screen monitor, by using a base and a thin film, both of which allow the permeation of X-ray and are excellent in heat radiating characteristic, and to prevent the same more effectively by arranging a filter on the upstream side of a screen so as to prevent the irradiation of long wavelength components to the screen. CONSTITUTION:A thin film 30b, made of ceramics such as alumina or the like, is formed on a base 30a, made of a metal plate of beryllium, aluminum, or the like, which allow the permeation of X-ray, so as to form a screen 30, which is to be provided in a beam line so as to be free in appearing and disappearing. It is desirable to arrange a filter 40 allowing the permeation of the X-ray in emitted light, and shading the light of longer wavelength than that of the same, on the upstream side of the screen 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen monitor which is installed in a beam line of a particle accelerator such as a synchrotron and monitors radiation emitted through the beam line.

[0002]

2. Description of the Related Art In recent years, a synchrotron is being developed as a relatively small particle accelerator having a diameter of 10 m or less,
By using synchrotron radiation (SOR light) which is radiation emitted from such synchrotron, for example, various fields such as manufacturing of VLSI circuits, diagnosis in the medical field, molecular analysis, structural analysis, etc. Expected to be applied.

FIG. 3 shows an outline of a small synchrotron. An electron beam generated by an electron generator 1 such as an electron gun is accelerated by a linear accelerator (linac) 2 to near the speed of light, and a deflecting electromagnet 3 is used. It is deflected and enters the storage ring 5 via the inflector 4. The electron beam incident on the storage ring 5 is converged by the converging electromagnet 7 while being given energy by the high-frequency accelerating cavity 6, is deflected by the deflection electromagnet 8, and continues to orbit the storage ring 5. Then, when the SOR light is deflected by the deflection electromagnet 8, the SOR light is emitted and emitted to the exposure device 10 through the beam line 9 which is a light extraction line for use.

In the particle accelerator as described above, SO
It is necessary to monitor whether or not the R light passes through a predetermined orbit in the beam line 9 at the beginning of operation or at an appropriate time to perform alignment, and a screen monitor for that purpose should be installed at a key point of the beam line 9. ing.

FIG. 4 to FIG. 6 show an example of a screen monitor which has been generally adopted conventionally. This is shown in Figure 4.
As shown in FIG. 3, a screen 15 that is inclined with respect to the beam line 9 in a plan view is configured to enter and leave the beam line 9. That is,
As shown in FIG. 5, a cylinder 16 is provided downward at the position above which the SOR light should be monitored.
Is moved up and down in the bellows 18, and a holder 19 shown in FIG. 6 is attached to the tip of the rod 18. The holder 19 is made of a metal plate such as stainless steel or copper, and its lower portion has a bottom portion 19a and side portions 19a.
It is formed in a frame shape by b and 19b, and the screen 15 is attached thereto. Then, by operating the cylinder 16 to move the screen 15 up and down, the screen 15 is projected and retracted in the beam line 9. As the material of the screen 15, a solid molding plate made of ceramics such as alumina is generally used, and a scale for measuring the irradiation position is drawn on the surface thereof.

When the SOR light is monitored by the screen monitor, as shown in FIG.
Is arranged in the beam line 9 in an inclined state, and then the surface of the screen 15 is irradiated with SOR light from the upstream side of the beam line 9. Then, since the position where the SOR light hits emits fluorescence and shines, the actual optical axis of the SOR light is confirmed by observing the position from the side of the beam line 9 through the viewport 20 with the camera 21, and based on that, Then, the optical axis is corrected and the alignment is performed if necessary. After completing such work, the screen 15
Is pulled up to withdraw above the beam line 9 to shift to normal operation.

[0007]

By the way, the conventional screen monitor as described above can be applied to a synchrotron of a small or medium scale without any trouble, but when it is applied to a synchrotron of a large scale and a large output, the SOR light is applied. Since the heat energy of the SO will be enormous, such high energy SO
Irradiation with R light may cause local melting of the screen 15, which is a ceramic molding plate.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a screen monitor applicable to a large-scale and high-energy particle accelerator.

[0009]

A screen monitor according to the present invention is a screen provided so as to be retractable in a beam line, and a thin metal film such as alumina is formed on the surface of a metal plate capable of transmitting X-rays as a base material. The one that has been adopted is adopted. And, especially when applied to a high-energy particle accelerator, the X-rays in the radiated light are provided upstream of the screen.
It is preferable to dispose a filter that transmits rays but blocks light having a longer wavelength.

[0010]

In the screen monitor of the present invention, when the screen is irradiated with radiant light, the ceramic thin film on the surface emits fluorescence, so that the irradiation position can be visually observed as in the conventional case. Since the metal plate as the base material and the ceramic thin film formed on the surface of the screen are both capable of transmitting X-rays and excellent in heat dissipation, the screen is not affected by irradiation with radiant light. It is effectively prevented from overheating or melting.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. The screen monitor of this embodiment is shown in FIG.
As shown in FIG. 5, the screen 30 is attached to the frame 31, and the frame 31 is attached to the cylinder 1 as shown in FIG.
Although the screen 30 is configured to be projected and retracted in the beam line 9 by moving up and down by 6, the screen 15 in the conventional screen monitor is made of a solid molded plate of ceramics. As shown in FIG. 1, the screen 30 in the embodiment has a metal plate as a base material 30a and a ceramic thin film 30b formed on the surface thereof.

As the metal plate which is the base material 30a, for example, a material having excellent X-ray transmission such as beryllium or aluminum is adopted, and its thickness is preferably about 1 mm. Further, the ceramic thin film 30b may be, for example, a vapor deposition film of alumina, and the thickness thereof may be about 0.1 to 1 μm.

Further, as shown in FIG. 2, the surface of the screen 30 is provided with a scale similar to the conventional one on the thin film 30b.
Form by scratching. Further, the holder 31 in this embodiment has the side portions 31b, 31 at the bottom thereof.
Only b is formed, and the bottom portion 19a of the conventional holder 19 shown in FIG. 6 is cut off.

The screen monitor of this embodiment is
Especially when applied to high energy synchrotron,
As shown in FIG. 1, a filter 40 is installed and used on the upstream side of the screen 30. The filter 40 is made of a metal plate such as beryllium or aluminum similar to the base material 30a of the screen 30, and transmits X-rays, which are short wavelength components in SOR light, but has a longer wavelength component, that is, visible light. It blocks light rays and infrared rays. The filter 40 may be provided in the beam line 9 together with the screen 30 so as to be retractable, but may be fixedly provided in the beam line 9.

As described above, the ceramic thin film 30 is formed on the surface of the base material 30a which is a metal plate having X-ray transparency.
The screen 30 having the structure in which b is formed has SO on its surface.
When the R light is irradiated, the thin film 30b emits fluorescence and shines, so that the SOR light can be monitored as in the conventional case. Then, in the screen monitor of this embodiment,
By adopting such a screen 30 and arranging and using the filter 40 on the upstream side thereof, the screen 30 is not melted even when irradiated with high-energy SOR light, and is therefore large-scale. It can be applied to a high output synchrotron.

That is, when the screen 30 and the filter 40 are arranged in the beam line 9, the SOR light to be monitored is applied to the filter 40, but the long wavelength component in the SOR light is cut by the filter 40 and the short wavelength component is cut. Only the component X-rays pass through the filter 40 and reach the screen 30. The X-rays that reach the screen 30 are absorbed by the ceramic thin film 30b and raise the temperature thereof. However, since the thin film 30b is sufficiently thin, the amount of X-rays absorbed is very small and the heat is released. Therefore, excessive temperature rise of the thin film 30b is naturally suppressed, and it is not melted. Further, most of the X-rays irradiated on the thin film 30b penetrate the thin film 30b and reach the base material 30a.
Since the X-rays are transmitted as they are because they are formed of a metal plate that transmits rays, the base material 30a is superior in heat dissipation to ceramics and the like.
It does not overheat a. Therefore, the screen 30 of this embodiment can be said to be substantially transparent thermally, and it is possible to reliably prevent the screen 30 from being overheated or melted by being irradiated with the SOR light.

In the conventional screen monitor, when the screen 15 is lowered into the beam line 9, the SOR is only temporarily displayed on the bottom portion 19a of the holder 19.
There is a concern that the bottom portion 19a of the holder 19 will be thermally damaged because of being irradiated with light. On the other hand, since the holder 31 in the screen monitor of the present embodiment has a shape in which the bottom portion is cut off, the holder 31 is not irradiated with SOR light and there is no risk of thermal damage. .

Further, the filter 40 in the above embodiment is not necessarily provided, and in the case of being applied to a synchrotron having a relatively small size and low energy, if the screen 30 receives a long wavelength component, there is no particular problem. It is also possible to omit the filter 40 and use the screen 30 alone.

[0019]

As described above, the screen monitor of the present invention is used as a screen that can be retracted into and out of the beam line. A metal plate that can transmit X-rays is used as a base material and a ceramic such as alumina is formed on the surface of the metal plate. Since a thin film is used, both the base material and the thin film transmit the irradiated X-rays and have excellent heat dissipation characteristics, so it seems that it will overheat or melt when receiving radiant light. What is effectively prevented. Further, in particular, if a filter that transmits X-rays in the emitted light but blocks long-wavelength light is arranged on the upstream side of the screen, it is possible to prevent irradiation of the screen with long-wavelength components, which is more effective. Yes, it is preferable to do so when applied to high energy particle accelerators.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view showing a screen and a filter in a screen monitor that is an embodiment of the present invention.

FIG. 2 is an assembly diagram of a screen and a holder in the screen monitor.

FIG. 3 is a diagram showing an outline of a synchrotron.

FIG. 4 is a plan sectional view showing an example of a conventional screen monitor.

FIG. 5 is a side view of the screen monitor.

FIG. 6 is an assembly diagram of a screen and a holder in the screen monitor.

[Explanation of symbols]

 9 beam line 30 screen 30a base material 30b thin film 31 holder 40 filter.

Claims (2)

[Claims] 1. A screen monitor installed on a beam line of a particle accelerator for monitoring radiant light extracted through the beam line, wherein a screen to be irradiated with the radiant light is provided so as to be retractable in the beam line. The screen monitor of a particle accelerator is characterized in that the screen is made of a metal plate that can transmit X-rays in radiated light as a base material, and a thin film of ceramics such as alumina is formed on the surface thereof. 2. The particle accelerator according to claim 1, further comprising a filter arranged on the upstream side of the screen for transmitting X-rays in the emitted light but blocking light having a longer wavelength. Screen monitor.