Self-shielded particle accelerator system

Abstract

To provide a self-shielded particle accelerator system that improves the maintainability of particle accelerators.SOLUTION: A self-shielded particle accelerator system includes a vacuum box 44 for accelerating particles, a rear wall 12 that shields radiation, and a front wall 14 that is movable with respect to the rear wall 12 and can shield radiation from the vacuum box 44 by surrounding the vacuum box 44 together with the rear wall 12. The rear wall 12 and the front wall 14 are joined to each other at a position where a person is accessible to the vacuum box 44 while the rear wall 12 and the front wall 14 are separated from each other.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a self-shielded particle accelerator system.

Background Art

[0002] In the production of a test agent labeled with a radioisotope used in positron emission tomography (PET) or in radiation therapy, a particle accelerator such as a cyclotron is used. In order to shield radiation such as neutron rays and gamma rays generated during the operation of the particle accelerator, a so-called self-shielded particle accelerator system including a radiation shielding wall surrounding the particle accelerator is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this type of self-shielded particle accelerator system, the radiation shielding wall is opened to perform maintenance of the particle accelerator inside the wall, and it is desirable to reduce the burden of maintenance work as much as possible. An object of the present invention is to provide a self-shielded particle accelerator system that improves the maintainability of a particle accelerator.

Means for Solving the Problems

[0005] The self-shielded particle accelerator system of the present invention comprises a vacuum box for accelerating particles, a first wall for shielding radiation, and a second wall that, together with the first wall, can shield radiation from the vacuum box by surrounding it and is movable relative to the first wall. The joining of the first wall and the second wall is performed at a position where a person can access the vacuum box while the first wall and the second wall are separated.

[0006] The joint between the first and second walls may be located on the side of the vacuum box. Furthermore, the end face of the first wall on the second wall side may be aligned with a plane intersecting the direction of movement of the second wall, and when viewed from a direction parallel to the plane, the end face may overlap the vacuum box.

[0007] The vacuum chamber may be equipped with an accelerating electrode, a beam detection device, a beam extraction device, and a target device, each accessible or removable from the side of the vacuum chamber.

[0008] The first wall has a first recess in its planar section, and the second wall has a second recess in its planar section that faces the first recess. The first wall and the second wall are joined together to form a radiation shield that houses a vacuum box in the internal space formed by the first recess and the second recess.

[0009] The self-shielded particle accelerator system of the present invention may further include a guide rail for guiding the movement of a second wall toward and away from a first wall. The second wall may also be supported by a slider portion that moves along the guide rail in the direction of extension of the guide rail, and the slider portion may allow the second wall to be displaced relative to the guide rail in a direction other than the direction of extension of the guide rail. The slider portion may also allow the second wall to be displaced relative to the guide rail in the width direction of the guide rail.

[0010] The guide rail is installed in a rail installation groove provided in the floor, and the rail installation groove may extend further longitudinally from the end of the guide rail and have a rail-free region where the guide rail is absent. [Effects of the Invention]

[0011] According to the present invention, a self-shielded particle accelerator system that improves the maintainability of particle accelerators can be provided. [Brief explanation of the drawing]

[0012] [Figure 1] This is an exploded perspective view showing the configuration of the radiation shield included in the cyclotron system according to the embodiment. [Figure 2] This is an exploded perspective view showing the configuration of the rear wall. [Figure 3] This diagram shows a connecting mechanism for linking adjacent blocks. [Figure 4] This is an exploded perspective view showing the configuration of the front wall. [Figure 5] This is an exploded perspective view showing the configuration of a cyclotron housed within a radiation shield. [Figure 6] This is a plan view showing how the cyclotron is housed within a radiation shield. [Figure 7] Figure 7(a) is a perspective view of the frame that makes up the FRU block, seen from above, and Figure 7(b) is a perspective view of this frame, seen from below. [Figure 8] Figure 8(a) is a perspective view of the frame that makes up the FLU block, seen from above, and Figure 8(b) is a perspective view of this frame, seen from below. [Figure 9] This is a perspective view showing the frame that makes up the FLS block. [Figure 10] This is a perspective view showing the frame that makes up the FRS block. [Figure 11] Figure 11(a) is a perspective view of the frame that makes up the RRU block, seen from above, and Figure 11(b) is a perspective view of this frame, seen from below. [Figure 12]FIG. 12(a) is a perspective view of the frame constituting the RLU block as seen from above, and FIG. 12(b) is a perspective view of this frame as seen from below. [Figure 13] It is a perspective view showing the frame constituting the RLS block. [Figure 14] It is a perspective view showing the frame constituting the RRS block. [Figure 15] It is a side view showing the state where the radiation shield is opened as seen from the X direction. [Figure 16] (a) to (c) are side views showing the state where the radiation shields of other examples are opened as seen from the X direction. [Figure 17] It is a plan view showing the guide rail. [Figure 18] (a) is a cross-sectional view around the guide rail showing the slider part included, and (b) is a plan view thereof. [Figure 19] (a) is a cross-sectional view around the guide rail showing another type of slider part included, and (b) is a cross-sectional view showing a modified example around the guide rail. [Figure 20] (a) is a cross-sectional view of the rail absent region, and (b) is a view showing the movement mechanism of the wall block according to the modified example.

Embodiments for Carrying Out the Invention

[0013] ] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0014] FIG. 1 is an exploded perspective view showing the configuration of the radiation shield 10 included in the cyclotron system 1 (self-shielding type particle accelerator system) (FIG. 6) according to the present embodiment. As shown in FIG. 6, the cyclotron system 1 includes a cyclotron 40 (particle accelerator) and a radiation shield 10 for surrounding the cyclotron 40 to shield radiation. The radiation shield 10 includes a rear wall body 12 and a front wall body 14 as shown in FIG. 1.

[0015] As shown in Figure 2, the rear wall 12 includes a rear right upper wall (RRU) block 16, a rear left upper wall (RLU) block 18, a rear right side wall (RRS) block 20, and a rear left side wall (RLS) block 22. The RRS block 20 and RLS block 22 are erected vertically and have a roughly L-shaped cross-section. The RRU block 16 and RLU block 18 extend horizontally and cover the upper parts of the RRS block 20 and RLS block 22. As shown in Figures 2 and 3, these RRU block 16, RLU block 18, RRS block 20, and RLS block 22 are connected at multiple points by fastening connecting parts C together with bolts 24 and nuts 26.

[0016] As shown in Figure 4, the front wall 14 has a front right upper wall (FRU) block 28, a front left upper wall (FLU) block 30, a front right side wall (FRS) block 32, and a front left side wall (FLS) block 34. The FRS block 32 and FLS block 34 are erected vertically and have a roughly L-shaped cross-section. The FRU block 28 and FLU block 30 extend horizontally and cover the upper parts of the FRS block 32 and FLS block 34. These FRU block 28, FLU block 30, FRS block 32, and FLS block 34 are connected at multiple points by fastening connecting parts C together with bolts 24 and nuts 26, similar to the rear wall 12.

[0017] By joining these rear wall 12 and front wall 14, a radiation shield 10 is formed. The cyclotron 40 is housed within the internal space R (see Figure 6) formed by this radiation shield 10, which is composed of the recess 12a of the rear wall 12 and the recess 14a of the front wall 14 in a planar cross-section, thus forming a self-shielded cyclotron system 1. Thus, "self-shielded" refers to a system in which the particle accelerator, such as a cyclotron, is shielded by a wall provided separately from the walls of the building in which the particle accelerator is installed, in order to shield the particle accelerator itself. In this sense, it differs from a particle accelerator system in which the wall that shields the particle accelerator constitutes part of the building.

[0018] As shown in Figure 5, the cyclotron 40 is a so-called vertical cyclotron and has a pair of magnetic poles 42, a vacuum chamber 44, and an annular yoke 46 surrounding the pair of magnetic poles 42 and the vacuum chamber 44. Parts of the pair of magnetic poles 42 are inserted into the vacuum chamber 44, and their upper surfaces face each other within the vacuum chamber 44 with a predetermined gap between them. Particles such as protons and deuterons are accelerated in multiple stages within the gap between these pair of magnetic poles 42.

[0019] Figure 6 is a plan view showing the cyclotron 40 housed within the radiation shield 10. For ease of explanation, Figure 6 shows the cyclotron with the RRU block 16, RLU block 18, FRU block 28, and FLU block 30 removed.

[0020] As shown in Figure 6, the cyclotron 40 is positioned approximately in the center of the radiation shield 10. With the rear wall 12 and the front wall 14 joined together, the wall surfaces that define the space housing the cyclotron 40 are referred to as the inner front surface 48, inner back surface 50, inner side surfaces 52, 54, and inner top surface (56 in Figure 1), respectively. At this time, the inner front surface 48 has lead (Pb) layers 58 and polyethylene (PE) layers 60 sequentially laminated on it, except for the portion facing the yoke 46. The inner side surfaces 52, 54 also have Pb layers 58 and PE layers 60 sequentially laminated on them. The inner back surface 50 has only a PE layer 60 laminated on it. Furthermore, as shown in Figures 1, 2, and 4, the inner top surface 56 also has Pb layers 58 and PE layers 60 sequentially laminated on it, except for the portion facing the yoke 46.

[0021] Next, with reference to Figures 7 to 10, the FRU block 28, FLU block 30, FRS block 32, and FLS block 34 that constitute the front wall 14 will be described in more detail. Furthermore, with reference to Figures 11 to 14, the RRU block 16, RLU block 18, RRS block 20, and RLS block 22 that constitute the rear wall 12 will be described in more detail.

[0022] Figure 7 is a perspective view showing the frame 70 that constitutes the FRU block 28. As shown in Figure 7, the frame 70 is configured as a box with an open top. The FRU block 28 is formed by filling this frame 70 with concrete. A concave step portion 72 is provided on the joint surface of the frame 70 that connects to the FLU block 30. A concave step portion 74 is also provided on the joint surface of the frame 70 that connects to the RRU block 16. A concave step portion 76 is also provided on the bottom wall surface of the frame 70. This step portion 76 is to avoid interference with the yoke 46. Ribs 78 are erected inside the frame 70 for reinforcement.

[0023] Furthermore, a hole 80 for inserting a bolt 24 is formed through the side wall of the frame that is joined to the FLU block 30. A space for fastening the bolt 24 and nut 26 is defined near this hole 80. In this way, a connecting part C is formed by the hole 80 and the space to connect with the FLU block 30. Furthermore, a hole 82 for inserting a bolt 24 is formed through the bottom wall of the frame 70 that is joined to the FRS block 32. A space for fastening the bolt 24 and nut 26 is defined near this hole 82. In this way, a connecting part C is formed by the hole 82 and the space to connect with the FRS block 32.

[0024] Next, Figure 8 is a perspective view showing the frame 90 that constitutes the FLU block 30. As shown in Figure 8, the frame 90 is configured as a box with an open top. The FLU block 30 is formed by filling this frame 90 with concrete. A convex step portion 92 is provided on the joint surface of the frame 90 that is joined to the FRU block 28. This step portion 92 fits into the concave step portion 72 of the FRU block 28. A concave step portion 94 is also provided on the joint surface of the frame 90 that is joined to the RLU block 18. A concave step portion 96 is also provided on the bottom wall surface of the frame 90. This step portion 96 is to avoid interference with the yoke 46. Ribs 98 are erected inside the frame 90 for reinforcement.

[0025] Furthermore, a hole 100 for inserting a bolt 24 is formed through the side wall of the frame 90 that is joined to the FRU block 28. A space for fastening the bolt 24 and nut 26 is defined near this hole 100. In this way, a connecting part C is formed by the hole 100 and the space to connect with the FRU block 28. Furthermore, a hole 102 for inserting a bolt 24 is formed through the bottom wall of the frame 90 that is joined to the FLS block 34. A space for fastening the bolt 24 and nut 26 is defined near this hole 102. In this way, a connecting part C is formed by the hole 102 and the space to connect with the FLS block 34.

[0026] Next, Figure 9 is a perspective view showing the frame 110 that constitutes the FLS block 34. As shown in Figure 9, the frame 110 is configured as a box with an open top. The FLS block 34 is formed by filling this frame 110 with concrete. A convex step portion 112 is provided on the joint surface of the frame 110 that is joined to the FRS block 32. Also, a hole 114 for inserting a bolt 24 is formed through the side wall of the frame 110 that is joined to the FRS block 32. Near this hole 114, a space (similar to that shown in Figure 3) is defined for fastening the bolt 24 and nut 26. In this way, a connecting portion C is formed by the hole 114 and the space to connect to the FRS block 32. Also, a concave step portion 116 is provided on the joint surface of the frame 110 that is joined to the RLS block 22. A concave step portion 118 is also provided on the inner surface of the frame 110. This stepped section 118 is designed to avoid interference with the yoke 46. Additionally, ribs 120 are erected within the frame 110 for reinforcement.

[0027] Furthermore, an auxiliary plate 124 is attached to the upper opening of the frame 110, which is joined to the FLU block 30, with a hole 122 formed through it for inserting a bolt 24. A space is defined near this hole 122 for inserting the bolt 24. In this way, the hole 122 and the space constitute a connecting part C for connecting to the FLU block 30.

[0028] Next, Figure 10 is a perspective view showing the frame 130 that constitutes the FRS block 32. As shown in Figure 10, the frame 130 is configured as a box with an open top. The FRS block 32 is formed by filling concrete into this frame 130. A concave step portion 132 is provided on the joint surface of the frame 130 that is joined to the FLS block 34. This step portion 132 fits into the convex step portion 112 of the FLS block 34. Also, a hole (not shown) for inserting a bolt 24 is formed through the side wall of the frame 130 that is joined to the FLS block 34. And a space (not shown) is defined near this hole for fastening the bolt 24 and nut 26. In this way, a connecting portion C is formed by the hole and the space to connect with the FLS block 34. Also, a concave step portion 136 is provided on the joint surface of the frame 130 that is joined to the RRS block 20. Furthermore, a concave step portion 138 is provided on the inner surface of the frame 130. This step portion 138 is intended to avoid interference with the yoke 46. In addition, ribs 140 are erected inside the frame 130 to provide reinforcement.

[0029] Furthermore, an auxiliary plate 144 is attached to the upper opening of the frame 130, which is joined to the FRU block 28, with a hole 142 formed through it for inserting a bolt 24. A space is defined near this hole 142 for inserting the bolt 24. In this way, the hole 142 and the space constitute a connecting part C for connecting to the FRU block 28.

[0030] The FRS block 32 and FLS block 34 described above are connected by tightening the connecting parts C with bolts 24 and nuts 26 while the stepped portions 112 and 132 provided on the joint surface are fitted together. Furthermore, the FRU block 28 and FLU block 30 described above are connected by tightening the connecting parts C with bolts 24 and nuts 26 while the stepped portions 72 and 92 provided on the joint surface are fitted together. Then, with the FRU block 28 and FLU block 30 placed on top of the FRS block 32 and FLS block 34, the front wall body 14 is constructed by tightening the connecting parts C with bolts 24 and nuts 26.

[0031] Furthermore, when placing the FRU block 28 and FLU block 30 on top of the FRS block 32 and FLS block 34, it is preferable to apply a fixing agent such as mortar to the joint surface beforehand. Doing so reduces the risk of gaps forming between the concrete exposed at the upper openings of the FRS block 32 and FLS block 34 and the lower surfaces of the FRU block 28 and FLU block 30.

[0032] Next, Figure 11 is a perspective view showing the configuration of the frame 150 that forms the RRU block 16. As shown in Figure 11, the frame 150 is configured as a box with an open top. The RRU block 16 is formed by filling this frame 150 with concrete. A concave step portion 152 is provided on the joint surface of the frame 150 that is joined to the RRU block 18. A convex step portion 154 is provided on the joint surface of the frame 150 that is joined to the FRU block 28. This step portion 154 fits into the concave step portion (74 in Figure 7) of the FRU block 28. A concave step portion 156 is also provided on the bottom wall surface of the frame 150. This step portion 156 is to avoid interference with the yoke 46. Ribs 158 are erected inside the frame 150 for reinforcement.

[0033] Furthermore, a hole 160 for inserting a bolt 24 is formed through the side wall of the frame 150 that is joined to the RLU block 18. A space for fastening the bolt 24 and nut 26 is defined near this hole 160. In this way, a connecting part C for connecting to the RLU block 18 is formed by the hole 160 and the space. Furthermore, a hole 162 for inserting a bolt 24 is formed through the bottom wall of the frame 150 that is joined to the RRS block 20. A space for fastening the bolt 24 and nut 26 is defined near this hole 162. In this way, a connecting part C for connecting to the RRS block 20 is formed by the hole 162 and the space. In addition, a through hole 164 is formed in the bottom wall of the frame 150. When concrete is filled, a pipe is inserted through this through hole 164 to form a passage T that penetrates vertically through the RRU block 16, as shown in Figure 1. This passage T is used to dissipate heat generated from the cyclotron 40 and to pass cables for supplying power to the cyclotron 40. Multiple such passages T may be formed as needed. Similar passages T may also be formed in the RLU block 18, FRU block 28, and FLU block 30 as needed.

[0034] Next, Figure 12 is a perspective view showing the frame 170 that constitutes the RLU block 18. As shown in Figure 12, the frame 170 is configured as a box with an open top. The RLU block 18 is formed by filling this frame 170 with concrete. A convex step portion 172 is provided on the joint surface of the frame 170 that is joined to the RRU block 16. This step portion 172 fits into the concave step portion 152 of the RRU block 16. A convex step portion 174 is also provided on the joint surface of the frame 170 that is joined to the FLU block 30. This step portion 174 fits into the concave step portion (94 in Figure 8) of the FLU block 30. A concave step portion 176 is also provided on the bottom wall surface of the frame 170. This step portion 176 is to avoid interference with the yoke 46. Ribs 178 are erected inside the frame 170 for reinforcement.

[0035] Furthermore, a hole 180 for inserting a bolt 24 is formed through the side wall of the frame 170 that is joined to the RRU block 16. A space for fastening the bolt 24 and nut 26 is defined near this hole 180. In this way, a connecting part C is formed by the hole 180 and the space to connect with the RRU block 16. Furthermore, a hole 182 for inserting a bolt 24 is formed through the bottom wall of the frame 170 that is joined to the RLS block 22. A space for fastening the bolt 24 and nut 26 is defined near this hole 182. In this way, a connecting part C is formed by the hole 182 and the space to connect with the RLS block 22.

[0036] Next, Figure 13 is a perspective view showing the frame 190 that constitutes the RLS block 22. As shown in Figure 13, the frame 190 is configured as a box with an open top. The RLS block 22 is formed by filling concrete into this frame 190. A concave step portion 192 is provided on the joint surface of the frame 190 that is joined to the RRS block 20. Also, a hole 194 for inserting a bolt 24 is formed through the side wall of the frame 190 that is joined to the RRS block 20. A space is defined near this hole 194 for fastening the bolt 24 and nut 26. In this way, a connecting portion C is formed by the hole 194 and the space to connect to the RRS block 20. Also, a convex step portion 196 is provided on the joint surface of the frame 190 that is joined to the FLS block 34. This step portion 196 fits into the concave step portion (116 in Figure 9) of the FLS block 34. Furthermore, ribs 198 are erected within the frame 190 to provide reinforcement.

[0037] Furthermore, an auxiliary plate 202 is attached to the upper opening of the frame 190, which is joined to the RLU block 18, with a hole 200 formed through it for inserting a bolt 24. A space is defined near this hole 200 for inserting the bolt 24. In this way, the hole 200 and the space constitute a connecting part C for connecting to the RLU block 18.

[0038] Next, Figure 14 is a perspective view showing the frame 210 that constitutes the RRS block 20. As shown in Figure 14, the frame 210 is configured as a box with an open top. The RRS block 20 is formed by filling concrete into this frame 210. A convex step portion 212 is provided on the joint surface of the frame 210 that is joined to the RLS block 22. This step portion 212 fits into the concave step portion 192 of the RLS block 22. Also, a hole 214 for inserting a bolt 24 is formed through the side wall of the frame 210 that is joined to the RLS block 22. A space for fastening the bolt 24 and nut 26 is defined near this hole 214. In this way, a connecting portion C is formed by the hole 214 and the space to connect with the RLS block 22. Also, a convex step portion 216 is provided on the joint surface of the frame 210 that is joined to the FRS block 32. This stepped portion 216 fits into the concave stepped portion (136 in Figure 10) of the FRS block 32. Furthermore, ribs 218 are erected within the frame 210 for reinforcement.

[0039] Furthermore, an auxiliary plate 222 is attached to the upper opening of the frame 210, which is joined to the RRU block 16, with a hole 220 formed through it for inserting a bolt 24. A space is defined near this hole 220 for inserting the bolt 24. In this way, the hole 220 and the space constitute a connecting part C for connecting to the RRU block 16.

[0040] The RRS block 20 and RLS block 22 described above are connected by tightening the connecting parts C with bolts 24 and nuts 26 while the stepped portions 192 and 212 provided on the joint surface are fitted together. Furthermore, the RRU block 16 and RLU block 18 described above are connected by tightening the connecting parts C with bolts 24 and nuts 26 while the stepped portions 152 and 172 provided on the joint surface are fitted together. Then, with the RRU block 16 and RLU block 18 placed on top of the RRS block 20 and RLS block 22, the rear wall body 12 is constructed by tightening the connecting parts C with bolts 24 and nuts 26.

[0041] Furthermore, when placing the RRU block 16 and RLU block 18 on top of the RRS block 20 and RLS block 22, it is preferable to apply a fixing agent such as mortar to the joint surface beforehand. Doing so reduces the risk of gaps forming between the concrete exposed at the upper openings of the RRS block 20 and RLS block 22 and the lower surfaces of the RRU block 16 and RLU block 18.

[0042] Then, as shown in Figure 1, the radiation shield 10 is formed by joining the front wall 14 and the rear wall 12. Note that there is no connecting means between the front wall 14 and the rear wall 12 as shown in Figure 3. This is because the rear wall 12 is the fixed side and the front wall 14 is the movable side, and maintenance of the cyclotron 40 housed inside is made possible by pulling the front wall 14 forward while being guided by the guide rail W. In addition to the guide rail W mentioned above, other guides that can guide the movement of the movable side block to move along a fixed line can be used. For example, if the movable side block moves in a double-door manner, hinges can be used.

[0043] As materials for forming the frames 70, 90, 110, 130, 170, 150, 190, and 210 that constitute each of the blocks described above, metal materials such as iron, FRP, etc., can be used. However, iron is preferred from the viewpoint of cost and strength.

[0044] Furthermore, when forming the frame sections 70, 90, 110, 130, 170, 150, 190, and 210 from iron, since iron has almost no radiation shielding ability, a thickness of approximately 1.0 mm to 10.0 mm is preferable from the viewpoint of weight reduction.

[0045] Furthermore, as the concrete filled into the frame sections of 70, 90, 110, 130, 170, 150, 190, and 210, it is preferable to use high-density shielding concrete with a high specific gravity, such as magnetite or other aggregates with a high specific gravity, as the concrete to be filled into the frame sections of 70, 90, 110, 130, 170, 150, 190, and 210, from the viewpoint of radiation shielding ability.

[0046] Furthermore, when filling the frame bodies 70, 90, 110, 130, 170, 150, 190, and 210 with concrete, it is preferable to suspend anchors G within the frame bodies 70, 90, 110, 130, 170, 150, 190, and 210 with wire or the like, so that a portion of the anchors G is fixed by the concrete, as shown in Figures 2 and 4. In this way, by attaching a detachable lifting device J to the anchors G, it becomes possible to transport the blocks.

[0047] As described in detail above, in the cyclotron system 1 according to this embodiment, the radiation shield 10 surrounding the cyclotron 40 is composed of a concrete-filled frame with concrete filled inside the frame bodies 70, 90, 110, 130, 170, 150, 190, and 210. Therefore, after filling the frame bodies 70, 90, 110, 130, 170, 150, 190, and 210 with concrete and allowing it to solidify, it can be used as is as a component of the radiation shield. In this way, the effort of removing the frame from the concrete is eliminated, making it easier to manufacture the radiation shield 10, and consequently easier to manufacture the cyclotron system 1. In addition, chips and cracks in the concrete are hidden by the frame bodies 70, 90, 110, 130, 170, 150, 190, and 210, eliminating the need to correct these defects and making manufacturing easier. Furthermore, mounting bases for peripheral devices can be freely attached to the frame sections 70, 90, 110, 130, 170, 150, 190, and 210, making it possible to change the mounting position of peripheral devices.

[0048] Furthermore, in the cyclotron system 1 according to this embodiment, since the radiation shield 10 is composed of multiple blocks 16, 18, 20, 22, 28, 30, 32, and 34, handling such as transportation and storage becomes easier compared to when the wall is constructed as a single piece.

[0049] Furthermore, in the cyclotron system 1 according to this embodiment, stepped portions (72 and 92, 112 and 132, 152 and 172, 192 and 212, 74 and 154, 94 and 174, 116 and 196, 136 and 216) are provided on the joint surfaces of adjacent blocks, and since these are joined in a fitted state, the risk of radiation leakage from between adjacent blocks can be reduced. In addition, since a fixing agent such as mortar is applied to the joint surface between the upper block and the lower block where it is difficult to provide such stepped portions, the risk of radiation leakage can be further reduced. Furthermore, if the frame bodies 70, 90, 110, 130, 170, 150, 190, and 210 are made of iron, deformation of each block can be suppressed and the accuracy of the joint surface can be improved, further reducing the risk of radiation leakage.

[0050] Furthermore, since a Pb layer 58, which is effective in shielding neutron rays, and a PE layer 60, which is effective in shielding gamma rays, are appropriately laminated on the inner surface of the radiation shield 10, the shielding of these radiations by concrete can be reinforced and the radiation shielding capacity can be improved. It is preferable to design the thickness of the concrete, Pb layer 58, and PE layer 60 taking into consideration the radiation attenuation characteristics and volume / weight ratio.

[0051] Furthermore, the RRU block 16 is provided with a passage T that connects the inside and outside of the wall, making it possible to pass cables for supplying power to the cyclotron 40 through it and to dissipate heat emitted from the cyclotron.

[0052] Furthermore, by providing a guide rail W to guide the movement of the movable front wall 14, the movement of the front wall 14 becomes easier, improving maintainability.

[0053] In the embodiment described above, the radiation shield 10 was composed of eight blocks 16, 18, 20, 22, 28, 30, 32, and 34, but it may be formed from a different number of blocks.

[0054] Referring again to Figure 5, the cyclotron 40 will be explained further. Figure 5 is an exploded perspective view of the cyclotron 40, showing the vacuum chamber 44 disassembled to reveal its interior. As mentioned above, the cyclotron 40 is a so-called vertical cyclotron, and the pair of magnetic poles 42, 42 face each other in the Y direction, with the particle beam acceleration trajectory in between. Viewed from the Z direction, the vacuum chamber 44 has a rectangle with a long side extending in the X direction. Particles generated in the vacuum chamber 44 are accelerated in a spiral trajectory in a plane perpendicular to the Y direction between the magnetic poles 42, 42. When the accelerated particle beam is irradiated onto a target, collisions between the particle beam and the target generate particle beams of other nuclides, and these particle beams of other nuclides are extracted from the outlet 261 on the side 45 of the vacuum chamber 44. The side 45 refers to the outer surface of the vacuum chamber 44 that is visible from the +X and -X directions. The inside of the vacuum chamber 44 is evacuated, and the particle generation space and acceleration space described above are in a vacuum.

[0055] As shown in Figure 5, the vacuum box 44 includes an ion source 251 for generating particles, an accelerating electrode 253 for accelerating the particle beam, a target device 255 having a target to which the particle beam is irradiated, a beam extraction device 257 for drawing the particle beam into the target, and a beam shutter 259 (beam detection device) for checking the beam current of the particle beam. Of these devices, the ion source 251, target device 255, beam extraction device 257, and beam shutter 259 are maintained relatively frequently, so they can be removed from the vacuum box 44 through the side 45. In addition, the particle beam exit port 261 from inside the vacuum box 44 is also provided on the side 45. Therefore, during maintenance work on the vacuum box 44, workers will mainly access the side 45 of the vacuum box 44.

[0056] Next, we will explain how to open and close the radiation shield 10. In the following, as shown in Figure 1, the direction of movement of the front wall 14 when opening the radiation shield 10 (the direction in which the guide rail W extends) will be defined as the Y direction, the width direction of the guide rail W will be defined as the X direction, and the vertically upward direction will be defined as the Z direction. Also, when using terms such as "front / rear," "front end / rear end," and "front / rear," the +Y direction will be defined as the front and the -Y direction as the rear.

[0057] Figure 15 is a side view showing the radiation shield 10 in an open state, viewed from the X direction. As mentioned above, the radiation shield 10 consists of a rear wall 12 (first wall) and a front wall 14 (second wall) installed on the building floor 301 and arranged in the front-to-back direction, joined to each other at a joint 303. During maintenance of the cyclotron 40, as shown in Figure 15, the front wall 14 moves forward parallel to the rear wall 12, guided by a guide rail W (Figure 1), while the rear wall 12 and the cyclotron 40 remain fixed to the building floor 301, separating from the rear wall 12. This opens the radiation shield 10 and exposes the cyclotron 40. From this state, the front wall 14 moves backward parallel to the rear wall 12, guided by the guide rail W (Figure 1), and joins to the rear wall 12, thereby closing the radiation shield 10.

[0058] As shown in Figure 4, the front wall 14 is composed of two blocks: a right wall block 305 and a left wall block 307. The right wall block 305 is composed of an FRU block 28 and an FRS block 32, and the left wall block 307 is composed of an FLU block 30 and an FLS block 34. The right wall block 305 and the left wall block 307 are bolted to each other at the aforementioned connecting section C, and move together as a single front wall 14 when the radiation shield 10 is opened or closed.

[0059] In this cyclotron system 1, the joint between the rear wall 12 and the front wall 14 is made in a position where a person (e.g., a maintenance worker) can access the vacuum chamber 44 while the rear wall 12 and the front wall 14 are separated. More specifically, the joint 303 (joint location) between the rear wall 12 and the front wall 14 is located on the side of the vacuum chamber 44. The joint 303 exists along a plane perpendicular to the Y direction and is located near the side surface 45 of the vacuum chamber. Even more specifically, as shown in Figure 15, when viewed from the X direction, the joint 303 is located near the vacuum chamber 44.

[0060] Considering the front end surface 12h of the rear wall 12 located at the joint 303, the front end surface 12h lies on a plane perpendicular to the Y direction. As shown in Figure 15, when the open radiation shield 10 is viewed from the X direction, the front end surface 12h may be positioned overlapping the vacuum box 44. Alternatively, as shown in Figure 16(a), it is even more preferable if the front end surface 12h is positioned behind the rear end 44b of the vacuum box 44. On the other hand, as shown in Figure 16(b), it is undesirable for the front end surface 12h to be positioned in front of the front end 44a of the vacuum box 44, and it is preferable that at least the front end surface 12h of the rear wall 12 is positioned behind the front end 44a of the vacuum box 44. In this embodiment, the front end 44a and rear end 44b of the vacuum box 44 are also the front end and rear end of the side surface 45 of the vacuum box 44.

[0061] The effects and benefits obtained from the positional relationship between the vacuum box 44 and the joint 303 as described above will now be explained. On the inner wall surfaces of the rear wall 12 and the front wall 14, a Pb layer 58 and a PE layer 60 are installed in the space between them and the cyclotron 40, and the distance in the X direction between the side surface 45 of the vacuum box 44 and the PE layer 60 is relatively small. Therefore, if the situation is as shown in Figure 16(b), it would be difficult to perform maintenance using the space between the side surface 45 of the vacuum box 44 and the PE layer 60. In contrast, if the situation is as shown in Figure 15 or Figure 16(a), when viewed from the X direction, at least a part of the side surface 45 of the vacuum box 44 is visible without being hidden by the rear wall 12. In this state, maintenance workers can access the side surface 45 of the vacuum box 44 relatively easily.

[0062] During maintenance of the cyclotron 40, access to the equipment contained in the vacuum chamber 44 is most often done from the side 45 of the vacuum chamber 44. However, with the above-described positional relationship, by simply moving the front wall 14, it is possible to easily access each piece of equipment through the side 45 of the vacuum chamber 44 without needing to move the rear wall 12 or the cyclotron 40. Therefore, the maintenance burden of the cyclotron 40 can be reduced, and the maintainability of the cyclotron 40 is improved.

[0063] Furthermore, as shown in Figure 16(c), for example, the RRU block 16 and RLU block 18 may be connected to the front wall 14, and when the radiation shield 10 is opened or closed, the front wall 14, RRU block 16, and RLU block 18 may move in the Y direction as a single movable side wall. In this case, the RRS block 20 and RLS block 22 function as the rear wall 12. In this case as well, the positional relationship between the vacuum box 44 and the front end surface 12h described above is set to be satisfied.

[0064] The front wall 14 is a heavy structure with a large wall thickness to shield against radiation. It is desirable that such a heavy front wall 14 be able to move stably and smoothly along the guide rail W. In particular, if the movement mechanism of the front wall 14 malfunctions due to an earthquake or the like, it will be difficult to move the heavy front wall 14 by other means, which could lead to the problem of being unable to open or close the radiation shield 10, making repair work on the cyclotron 40 impossible. Therefore, the cyclotron system 1 is equipped with the mechanism described below.

[0065] As shown in Figure 1, in the cyclotron system 1, there are four parallel guide rails W extending in the Y direction in order to move the front wall 14 as described above. When distinguishing between the guide rails W, they are called guide rails W1, W2, W3, and W4 in order of their arrangement in the X direction. Figure 17 is a plan view showing the guide rails W1 to W4 with the radiation shield 10 and cyclotron 40 removed. In Figure 17, the installation positions of the rear wall 12, front wall 14, and cyclotron 40 are indicated by dashed lines.

[0066] Each guide rail W1 to W4 is equipped with a slider section 311 that supports the front wall 14 and is slidable along the guide rail W in the Y direction. As described above, the front wall 14 can move in the Y direction as the slider section 311 slides along each guide rail W. Additionally, guide rails W2 and W3 are equipped with slider sections 313 that support the cyclotron 40 at its four corners and are slidable along the guide rail W in the Y direction. As the slider section 313 slides along each guide rail W, the cyclotron 40 can also move in the Y direction. Note that the slider section 313 has the same configuration as the slider section 311, so below we will describe the slider section 311 and omit a detailed description of the slider section 313.

[0067] The right wall block 305 of the front wall 14 is supported at three points by a total of three slider parts 311: two slider parts 311 installed on guide rail W1 and one slider part 311 installed on guide rail W2. In a plan view, the centroid of the triangle formed by these three slider parts 311 roughly coincides with the centroid of the right wall block 305. Similarly, the left wall block 307 of the front wall 14 is supported at three points by a total of three slider parts 311: two slider parts 311 installed on guide rail W4 and one slider part 311 installed on guide rail W3. In a plan view, the centroid of the triangle formed by these three slider parts 311 roughly coincides with the centroid of the left wall block 307. With this configuration, by releasing the bolt fastening of the connecting part C (Figure 14) and separating the right wall block 305 and the left wall block 307, the right wall block 305 and the left wall block 307 can be moved separately in the Y direction.

[0068] The following mainly describes the configuration of the guide rail W and slider section 311 related to the right wall block 305. However, since the left wall block 307 has a similar configuration that is symmetrical to the right wall block 305, redundant explanations will be omitted.

[0069] Of the three slider sections 311 that support the right wall block 305, the one installed on either guide rail W1 or W2 has an additional function described below. Hereafter, the slider section 311 of the type with this additional function will be denoted as "311A", and the other slider sections 311 will be denoted as "311B" to distinguish them. In this embodiment, the one slider section 311 installed on guide rail W2 corresponds to slider section 311A, and the two slider sections 311 installed on guide rail W1 correspond to slider sections 311B.

[0070] In addition to the functions of the slider section 311B, the slider section 311A ​​also has the function of allowing the right wall block 305 to be displaced relative to the guide rail W2 in directions other than the Y direction. Specifically, the slider section 311A ​​guides the movement of the right wall block 305 in the Y direction relative to the guide rail W2, and also allows the right wall block 305 to be displaced in the X direction relative to the guide rail W2. More specifically, relative displacement in the X direction between the slider section 311A ​​and the right wall block 305 is permitted.

[0071] Similarly to the right wall block 305, of the three slider sections 311 supporting the left wall block 307, one slider section 311 installed on the guide rail W3 corresponds to slider section 311A, and the two slider sections 311 installed on the guide rail W4 correspond to slider section 311B.

[0072] The structure around the guide rail W and the structure of the slider section 311 will be further explained with reference to Figures 17, 18, and 19. Figure 18(a) is a cross-sectional view of the area around the guide rail W including the slider section 311A, and Figure 18(b) is a plan view thereof. Figure 19(a) is a cross-sectional view of the area around the guide rail W including the slider section 311B, and Figure 19(b) is a cross-sectional view showing a modified example of the area around the guide rail W.

[0073] As shown in Figures 18(a) and (b), a rail installation groove 315 is constructed in the floor 301 by excavating, has a rectangular cross-section, and extends in the Y direction, at the position corresponding to the guide rail W. The guide rail W is laid on the bottom surface in the center of the rail installation groove 315. Note that detailed illustrations of the guide rail W and the rail installation groove 315 are omitted in Figure 1.

[0074] The slider section 311A ​​has a slider body section 317, which is fitted into the guide rail W with a U-shaped guide surface 319 that surrounds the upper and side surfaces of the guide rail W. A flat roller 321 (width direction displacement allowance section) is attached to the upper surface of the slider body section 317, and the right wall block 305 is placed on the upper surface of the flat roller 321. The flat roller 321 has a plurality of cylindrical rollers 323 arranged in the X direction, each rotating around its axis in the Y direction, and the rotation of these rollers 323 allows for relative displacement of the right wall block 305 in the X direction with respect to the slider body section 317. In other words, the aforementioned additional function of allowing displacement of the right wall block 305 in the X direction with respect to the guide rail W is realized by the flat roller 321.

[0075] The slider body 317 has rolling elements 325 (for example, spherical balls) interposed between the guide surface 319 and the upper and side surfaces of the guide rail W, which roll in the Y direction. The presence of such rolling elements 325 reduces the sliding resistance of the slider body 317 against the guide rail W, allowing the slider body 317 to move smoothly along the guide rail W in the Y direction, and consequently, the Y-direction movement of the right wall block 305 to be stable and smooth.

[0076] As shown in Figure 19(a), the slider section 311B is the same as the slider section 311A ​​but without the flat roller 321. In the slider section 311B, the right wall block 305 is placed directly on the upper surface of the slider body section 317. Therefore, the right wall block 305 and the slider body section 317 do not displace relative to each other, and the right wall block 305 is not allowed to displace in the X direction relative to the guide rail W. In other respects, the slider section 311B has the same configuration as the slider section 311A, so the same reference numerals are used in the drawings and redundant explanations are omitted.

[0077] The effects and benefits obtained by the moving mechanism including the guide rail W and slider section 311 described above will now be explained.

[0078] The movement mechanism for moving the front wall 14 includes a plurality of guide parts (slider parts 311 and guide rails W) that support wall blocks (right wall block 305 or left wall block 307) that constitute at least a part of the front wall 14 and guide the wall blocks in the direction of movement (Y direction) of the front wall 14, and in all but one of the plurality of guide parts, displacement of the wall block in a direction intersecting the above direction of movement is permitted. In a specific example of this embodiment, of the three slider parts 311 that support the right wall block 305, the slider part 311A ​​is installed on either guide rails W1 or W2 (in this embodiment, guide rail W2), and the slider part 311A ​​allows displacement of the right wall block 305 in the X direction.

[0079] With this configuration, even if there is some disturbance in the Y-direction movement of the right wall block 305, such as insufficient linearity or parallelism of the guide rails W1 and W2, or insufficient weight balance of the right wall block 305 supported by the guide rails W1 and W2, the disturbance is absorbed by the relative displacement of the right wall block 305 and the guide rail W2 in the rail width direction (X direction), so that the Y-direction movement of the right wall block 305 is stable and smooth. Similarly, the Y-direction movement of the left wall block 307 is also stable and smooth. Conversely, the accuracy of the parallelism of the guide rail W can be relaxed, so the burden of accuracy control during the construction of the guide rail W is reduced. Also, even if an external force such as an earthquake acts on the right wall block 305, the slider part 311A ​​releases the external force in the rail width direction on one of the guide rails W, so the possibility of damage to the front wall body 14 or the guide rail W is reduced.

[0080] Furthermore, of the four slider sections 313 supporting the cyclotron 40, the two slider sections 313 installed on either one of the guide rails W2 or W3 may also have the same function as slider section 311A. This allows the cyclotron 40 to move stably and smoothly in the Y direction, using the same principle as the right wall block 305.

[0081] Furthermore, with a structure in which a rail installation groove 315 is constructed in the floor 301 and a guide rail W is installed within this rail installation groove 315, the straightness of the guide rail W can be easily ensured without being affected by the undulations present on the floor surface of the floor 301. In other words, the smoothness of the bottom surface of the rail installation groove 315 and the straightness of the guide rail W are easier to manage and ensure than the smoothness of the floor 301. Therefore, the movement of the right wall block 305 in the Y direction can be performed stably and smoothly regardless of the undulations on the floor surface of the floor 301. Similarly, the movement of the left wall block 307 in the Y direction can also be performed stably and smoothly.

[0082] As described above, the guide rails W and slider section 311 enable stable and smooth movement of the right wall block 305 and the left wall block 307 in the Y direction. Therefore, even if the floor 301 becomes uneven or the parallelism of the guide rails W deteriorates due to a disaster such as an earthquake, the right wall block 305 and the left wall block 307 can be moved in the Y direction to open the radiation shield 10, allowing for repair work on the cyclotron 40 and other such operations.

[0083] Furthermore, with a structure in which a rail installation groove 315 is constructed in the floor 301 and a guide rail W is installed within the rail installation groove 315, the guide rail W can be installed at a lower position relative to the floor 301, and the position of the upper surface of the slider section 311 can be lowered. This makes it easier to reduce the clearance S (Figure 18(a)) between the bottom surface of the right wall block 305 and the upper surface of the floor 301. Similarly, it is easier to reduce the clearance S between the bottom surface of the left wall block 307 and the upper surface of the floor 301. By reducing the clearance S, radiation leakage from the cyclotron 40 to the outside through this clearance S is suppressed, enabling stable radiation leakage management. From this viewpoint, it is preferable to bring the height of the upper surface of the slider section 311 and the height of the upper surface of the floor 301 as close as possible to reduce the clearance S as much as possible.

[0084] If the height of the upper surface of the slider portion 311 becomes lower than the height of the upper surface of the floor 301, a step 326 may be formed on the bottom surface of the right wall block 305, as shown in Figure 19(b), so that the portion of the bottom surface of the right wall block 305 facing the floor 301 is higher than the upper surface of the floor 301. This avoids interference between the right wall block 305 and the floor 301 and ensures a clearance S between the bottom surface of the right wall block 305 and the floor 301.

[0085] Furthermore, since the guide rail W and slider section 311 are provided directly below the front wall 14, the footprint of the cyclotron system 1 can be kept smaller compared to, for example, a system in which wheels and rails are provided on the side of the front wall 14. As a result, the installation area required for the cyclotron system 1 can be kept small, and the required area of ​​the room in which it is installed can be reduced.

[0086] Furthermore, if the rail installation groove 315 is shallow, the floor thickness of the building floor where the rail installation groove 315 is installed can be reduced, and as a result, the weight of concrete used in the construction of the floor is reduced. Also, since a large floor thickness is not required for the installation floor, it becomes possible, for example, to install the cyclotron system 1 by simply remodeling the building floor.

[0087] As mentioned above, a structure is adopted in which a rail installation groove 315 is constructed in the floor 301 and the guide rail W is installed within this rail installation groove 315. Furthermore, since the slider part 311 engages with the guide rail W using the rolling elements 325 of the slider body part 317, it is not possible to lift the slider part 311 away from the guide rail W. Therefore, there is a concern that it will be difficult to remove the slider part 311 from the guide rail W when performing maintenance or replacement of the slider part 311.

[0088] As a countermeasure, as shown in Figure 17, a rail-free region 327 is provided at the front end of each rail installation groove 315 where no guide rail W is installed. Figure 20(a) is a cross-sectional view of the rail-free region 327. That is, the rail installation groove 315 extends further in the +Y direction than the front end surface of the guide rail W, and the guide rail W is not present in this extended portion. The Y-direction length of this rail-free region 327 is longer than the Y-direction length of the slider portion 311.

[0089] With this configuration, the slider section 311, which requires maintenance or replacement, can be easily removed from the guide rail W through the rail-free area 327. That is, the right wall block 305 (or left wall block 307) is jacked up to separate the slider section 311 from the bottom surface of the block, and then the slider section 311 is moved along the guide rail W to the rail-free area 327. Once the slider section 311 reaches the front end of the guide rail W, it can be pulled further forward from the front end surface of the guide rail W towards the rail-free area 327, thus easily removing the slider section 311 from the guide rail W. The slider section 311 can then be attached to the guide rail W by the reverse procedure.

[0090] The attachment and detachment of the slider section 311 to the guide rail W using the rail-free area 327 may be performed in the following procedure. First, a temporary rail slightly shorter in the Y direction than the rail-free area 327 is prepared and placed on the extension of the guide rail W within the rail-free area 327. Then, the slider section 311 to be removed is moved along the guide rail W to the rail-free area 327 and transferred onto the temporary rail. After that, the slider section 311 together with the temporary rail can be removed from the rail-free area 327. Alternatively, if the slider section 311 to be attached is prepared while placed on the temporary rail, it can be attached to the guide rail W by the reverse procedure described above. When the rail-free area 327 is not in use, the rail-free area 327 may be closed by inserting a groove-filling block 329 as shown in Figure 20(a).

[0091] The present invention can be implemented in various forms, including the embodiments described above, by making various changes and improvements based on the knowledge of those skilled in the art. Furthermore, it is possible to construct modified versions by utilizing the technical matters described in the embodiments described above. The configurations of each embodiment may be used in appropriate combinations.

[0092] Instead of the guide rail W and slider section 311 in the above-described embodiment, a wheeled moving mechanism as shown in Figure 20(b) may be employed. The mechanism in Figure 20(b) comprises two sets of trolleys 331 and 332 that support the wall block 330 (right wall block 305 or left wall block 307), and two sets of guide rails W11 and W12 that guide the trolleys 331 and 332 in the Y direction, respectively. The left and right wheels 333 of the trolley 331 run on each of the two rails included in the guide rail W11. Similarly, the left and right wheels 334 of the trolley 332 run on each of the two rails included in the guide rail W12. The aforementioned flat roller 321 is sandwiched between the top surface of the trolley 331 and the bottom surface of the wall block 330, and this structure allows displacement of the wall block 330 in the X direction relative to the guide rail W11. On the other hand, the bottom surface of the wall block 330 is in direct contact with the top surface of the trolley 332.

[0093] Furthermore, in the cyclotron system 1, it is not essential that there be a structure that allows displacement of the right wall block 305 (or left wall block 307) in the X direction relative to the guide rail W. That is, for example, all three slider sections 311 (Figure 17) supporting the right wall block 305 may be slider sections 311B that do not allow displacement of the right wall block 305 in the X direction. Similarly, all three slider sections 311 (Figure 17) supporting the left wall block 307 may be slider sections 311B.

[0094] Furthermore, in the mechanism shown in Figure 20(b), the flat roller 321 may be omitted, and the bottom surface of the wall block 330 may be in direct contact with the upper surface of the trolley 331. In the mechanism shown in Figure 20(b), the wheels 333 and 334 themselves, unlike the slider body 317 (Figure 19(a)), are slightly displaceable in the X direction relative to the guide rails W11 and W12. Therefore, in the mechanism shown in Figure 20(b), the wheels 333 and 334 themselves have the function of allowing the wall block 330 to be displaced in the X direction. Thus, even when the bottom surface of the wall block 330 is in direct contact with the upper surfaces of both trolleys 331 and 332, the effect of being able to move the wall block 330 stably and smoothly in the Y direction can be obtained.

[0095] Furthermore, in the above-described embodiment, the front end surface 12h of the rear wall 12 located at the joint 303 is aligned with a plane perpendicular to the Y direction, but this is not limited to this, and the front end surface 12h may be aligned with a plane intersecting the Y direction. In other words, the joint 303 between the rear wall 12 and the front wall 14 is not limited to being aligned with a plane perpendicular to the Y direction, but may be aligned with a plane intersecting the Y direction. [Explanation of Symbols]

[0096] 1...Cyclotron system (self-shielded particle accelerator system), 10...Radiation shield, 12...Rear wall (first wall), 12a...Recess (first recess), 12h...Front end face, 14...Front wall (second wall), 14a...Recess (second recess), 44...Vacuum box, 253...Accelerating electrode, 255...Target device, 257...Beam extraction device, 259...Beam shutter (beam detection device), 303...Joint (joint position), 311, 311A, 311B...Slider section, 315...Rail installation groove, 321...Flat roller (width direction displacement allowable section), 325...Rolling element, 327...Rail-free area, R...Internal space, W, W1, W2, W3, W4...Guide rails.

Claims

1. A vacuum box that accelerates particles, The first wall shields against radiation, The structure comprises a second wall that, together with the first wall, surrounds the vacuum box and is capable of shielding radiation from the vacuum box, and is movable relative to the first wall, The end face of the first wall on the side of the second wall is located along a plane that intersects the direction of movement of the second wall. When viewed from a direction parallel to the plane, the end face is positioned to overlap the vacuum box, The vacuum chamber contains components that are accessible or removable from a direction parallel to the plane. Self-shielded particle accelerator system.

2. The self-shielded particle accelerator system according to claim 1, wherein the joint between the first wall and the second wall is located on the side of the vacuum box.

3. The first wall has a first recess in its planar section, and the second wall has a second recess in its planar section that is opposite to the first recess. The self-shielded particle accelerator system according to claim 1, wherein the first wall and the second wall are joined together to form a radiation shield that houses the vacuum box in the internal space formed by the first recess and the second recess.

4. The self-shielded particle accelerator system according to claim 1, further comprising guide rails for guiding the movement of the second wall toward and away from the first wall.

5. A vacuum box that accelerates particles, The first wall shields against radiation, The structure comprises a second wall that, together with the first wall, surrounds the vacuum box and is capable of shielding radiation from the vacuum box, and is movable relative to the first wall, The joining of the first wall and the second wall is performed in a position where a person can access the vacuum box while the first wall and the second wall are separated. The system further includes guide rails for guiding the movement of the second wall so as to approach and move away from the first wall, The second wall is supported by a slider that moves along the guide rail in the direction of extension of the guide rail. The slider section allows the second wall to be displaced relative to the guide rail in a direction other than the direction of extension of the guide rail, in a self-shielding particle accelerator system.

6. The slider portion allows the second wall to be displaced relative to the guide rail in the width direction of the guide rail, as described in claim 5.

Images