JP2018136259A - Neutron deceleration body and neutron irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a neutron deceleration body and a neutron irradiation device that can increase an extraction number of low-speed neutrons.SOLUTION: A neutron deceleration body decelerates neutrons. The neutron deceleration body includes a body part formed from material to decelerate neutrons, and a groove part formed on a front edge in an extraction direction of the neutrons of the body part. In the body part, a sum of a superficial area of a face of which the normal is vertical to the extraction direction and a superficial area of a face of which the normal is parallel to the extraction direction of groove faces forming the groove part is equal to or less than 50% of a superficial area of the entire groove faces.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a neutron moderator and a neutron irradiation apparatus.

  The neutron irradiation device includes an acceleration device that accelerates and ejects charged particles, a target that generates fast neutrons by irradiation of charged particles emitted from the acceleration device, and slow neutrons that decelerate the fast neutrons generated by the target ( A neutron moderator that generates thermal neutrons, epithermal neutrons, or cold neutrons (see, for example, Patent Document 1). Low-speed neutrons generated by the neutron moderator are taken out in a predetermined direction, and are used, for example, for various examinations, medical treatment, and radioisotope generation.

Japanese Patent Laid-Open No. 2015-145882

  In the neutron irradiation apparatus described in Patent Document 1 and the like, it is required to increase the number of low-speed neutrons to be extracted.

  The present invention has been made in view of the above, and an object thereof is to provide a neutron moderator and a neutron irradiation apparatus capable of increasing the number of low-speed neutrons extracted.

  A neutron moderator according to the present invention is a neutron moderator that decelerates neutrons, and a main body formed using a material that decelerates the neutrons, and a front end surface of the main body in the neutron extraction direction. And the main body portion has a surface area of a surface whose normal is perpendicular to the take-out direction and a surface area of a surface whose normal is parallel to the take-out direction among the groove surfaces forming the groove. Is 50% or less of the surface area of the entire groove surface.

  The present inventor comprises a neutron moderator for decelerating neutrons, a main body formed using a material for decelerating neutrons, and a groove formed on the front end surface in the neutron extraction direction of the main body, The sum of the surface area of the surface where the main body forms the groove portion and whose normal is perpendicular to the extraction direction and the surface area of the surface whose normal is parallel to the extraction direction is 50% of the surface area of the entire groove surface It has been found that the number of low-speed neutrons extracted increases when According to the present invention, it is provided with a main body formed using a material for decelerating neutrons, and a groove formed on the front end surface of the main body in the neutron extraction direction, and the main body forms the groove. Of the groove surfaces, the sum of the surface area of the surface whose normal is perpendicular to the extraction direction and the surface area of the surface whose normal is parallel to the extraction direction is 50% or less of the surface area of the entire groove surface. The number of take-outs can be increased.

  A neutron moderator according to the present invention is a neutron moderator that decelerates neutrons, and a main body formed using a material that decelerates the neutrons, and a front end surface of the main body in the neutron extraction direction. And the groove portion has a portion that gradually expands in the take-out direction, and the main body portion is a groove that forms the groove portion in a plan view when viewed from the front in the take-out direction. The area of the portion of the surface that gradually expands in the take-out direction is 50% or more with respect to the area of the entire groove surface.

  The present inventor comprises a neutron moderator for decelerating neutrons, a main body formed using a material for decelerating neutrons, and a groove formed on the front end surface in the neutron extraction direction of the main body, The groove portion has a portion that gradually expands in the take-out direction, and the main body portion has a groove area that is the portion of the groove surface that forms the groove portion that gradually widens in the take-out direction when viewed from the front in the take-out direction. It has been found that the number of low-speed neutrons extracted increases when the area is 50% or more of the entire surface area. According to the present invention, it is provided with a main body formed using a material for decelerating neutrons, and a groove formed on the front end surface of the main body in the neutron extraction direction, and the groove is gradually removed in the extraction direction. The main body portion has an area of a portion gradually expanding in the take-out direction of the groove surface constituting the groove portion in a plan view when viewed from the front in the take-out direction with respect to the area of the entire groove surface. %, The number of low-speed neutrons extracted can be increased.

  In the neutron moderator described above, the main body portion may have a size of the groove portion in the take-out direction of 50% or more with respect to a size in the take-out direction of the entire main body portion.

  In the neutron moderator, the present inventors more effectively increase the number of low-speed neutrons to be extracted when the dimension of the groove part in the extraction direction is 50% or more of the dimension in the extraction direction of the entire body part. I found out that I can. According to the present invention, since the dimension of the groove part in the take-out direction is 50% or more with respect to the dimension in the take-out direction of the entire main body part, the number of low-speed neutrons taken out can be increased more effectively.

  In the neutron moderator described above, the main body portion may be arranged such that the groove surface intersects with a virtual plane perpendicular to the extraction direction at an angle within a predetermined range.

  The present inventor more effectively increases the number of low-speed neutrons to be extracted when the groove surface is inclined at an angle within a predetermined range with respect to a virtual plane perpendicular to the extraction direction in the neutron moderator. I found out that I can. According to the present invention, since the groove surface intersects with a virtual plane perpendicular to the extraction direction at an angle within a predetermined range, the number of low-speed neutrons extracted can be increased more effectively.

  In the neutron moderator described above, the predetermined range may be an angle of 60 ° to 85 °.

  The present inventor has found that the number of low-speed neutrons to be extracted is more effectively increased when the predetermined range is an angle of 60 ° to 85 °. According to the present invention, since the predetermined range is an angle of 60 ° to 85 °, the number of low-speed neutrons to be extracted is more effectively increased.

  In the neutron moderator described above, the groove may have a shape that gradually widens in the extraction direction.

  The present inventor has found that in the neutron moderator, the number of low-speed neutrons extracted can be increased more effectively when the groove portion has a shape that gradually expands in the extraction direction. According to the present invention, the number of low-speed neutrons extracted can be increased more effectively because the groove portion has a shape that gradually expands in the extraction direction.

  In the neutron moderator described above, the main body has a plurality of protrusions formed in a tapered shape in the extraction direction, and the groove may be formed between the plurality of protrusions. Good.

  According to the present invention, since the main body portion has a plurality of projecting portions formed in a tapered shape in the take-out direction, a shape in which the groove portion expands in the take-out direction can be easily formed. Thereby, the number of low-speed neutrons extracted can be increased more effectively with an easy configuration.

  In the neutron moderator described above, the protrusion may be wedge-shaped or conical.

  According to the present invention, since the protruding portion has a wedge shape or a cone shape, it is possible to realize a tapered shape that is easy to manufacture.

  A neutron moderator according to the present invention is a neutron moderator that decelerates neutrons, and a main body formed using a material that decelerates the neutrons, and a front end surface of the main body in the neutron extraction direction. And a groove portion that is formed and gradually expands in the take-out direction.

  The present inventor has found that in the neutron moderator, the number of low-speed neutrons extracted can be increased more effectively when the groove portion has a shape that gradually expands in the extraction direction. According to the present invention, the number of low-speed neutrons extracted can be increased more effectively because the groove portion has a shape that gradually expands in the extraction direction.

  The neutron irradiation apparatus according to the present invention includes an accelerating apparatus that accelerates and ejects charged particles, a target that emits neutrons by being irradiated with the charged particles ejected from the acceleration apparatus, and the neutron generated by the target. And the above-described neutron moderator that irradiates in the extraction direction.

  According to the present invention, since the neutron moderator capable of increasing the number of low-speed neutrons to be extracted is provided, a neutron irradiation apparatus with high neutron irradiation efficiency can be obtained.

  Said neutron irradiation apparatus WHEREIN: The said extraction direction may be a side with respect to the irradiation direction of the said charged particle irradiated to the said target.

  According to the present invention, it is possible to suppress extraction of fast neutrons as compared with the case where the extraction direction is set to a direction along the irradiation direction of the charged particles.

  According to the present invention, it is possible to increase the number of low-speed neutrons extracted.

FIG. 1 is a schematic diagram illustrating an example of a neutron irradiation apparatus according to the present embodiment. FIG. 2 is an enlarged view showing a main part of the neutron irradiation apparatus. FIG. 3 is a perspective view showing an example of a neutron moderator according to the present embodiment. FIG. 4 is a diagram illustrating a neutron moderator according to a modification. FIG. 5 is a diagram showing a neutron moderator according to a modification. FIG. 6 is a diagram illustrating a neutron moderator according to a modification. FIG. 7 is a view showing a neutron moderator according to a modification. FIG. 8 is a diagram illustrating a neutron moderator according to a modification. FIG. 9 is a diagram illustrating a neutron moderator according to a modification. FIG. 10 is a diagram illustrating a neutron moderator according to a modification.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of each embodiment described below can be combined as appropriate. Some components may not be used. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a schematic diagram illustrating an example of a neutron irradiation apparatus 1 according to the present embodiment. The neutron irradiation apparatus 1 irradiates the irradiated object S with neutrons N. The neutron irradiation apparatus 1 is used, for example, for inspection applications, medical applications, radioisotope generation applications, and the like.

  As shown in FIG. 1, the neutron irradiation apparatus 1 includes an acceleration device 2 that accelerates charged particles and emits charged particles P, and an adjustment device 3 that adjusts the irradiation state of the charged particles P emitted from the acceleration device 2. A target 5 that generates neutrons N by irradiation of charged particles P, a neutron moderator 6 that decelerates neutrons N generated by the target 5, a collimator 7 that collimates the neutrons N emitted from the neutron moderator 6, It has. The irradiated object S is irradiated with neutrons N emitted from the collimator 7.

  The acceleration device 2 includes a circular accelerator or a linear accelerator. The acceleration device 2 accelerates charged particles (protons, electrons, or heavy particles), generates charged particles (proton beams, electron beams, or heavy particle beams) P, and emits them in a predetermined irradiation direction. Hereinafter, the irradiation direction of the charged particles P is referred to as a first direction D1.

  The adjustment device 3 includes a plurality of electromagnets, and adjusts the irradiation state of the charged particles P emitted from the acceleration device 2 in the first direction D1. The irradiation state of the charged particles P includes adjustment of the traveling direction of the charged particles P and shaping of the charged particles P. The adjusting device 3 suppresses the divergence of the charged particles P and focuses the charged particles P. The adjusting device 3 guides the charged particles P ejected from the acceleration device 2 to the scanning device 4.

  In the present embodiment, the neutron irradiation apparatus 1 includes a scanning device 4 that scans the charged particles P. The scanning device 4 scans the charged particles P and adjusts the irradiation position of the charged particles P with respect to the target 5. Further, the scanning device 4 shapes the charged particles P irradiated to the target 5. The scanning device 4 may be omitted.

  The charged particles P emitted from the acceleration device 2 and passed through the adjustment device 3 and the scanning device 4 are irradiated to the target 5. The target 5 generates neutrons N by irradiation with charged particles P. In the target 5, for example, high-energy fast neutrons are generated as the neutrons N. The target 5 is a neutron generating member that generates neutrons. The target 5 includes a liquid or solid plate-like member formed of, for example, beryllium (Be), lithium (Li), or a compound containing them. The target 5 may be a circular or rectangular plate-shaped solid member, or heated liquid lithium. For example, liquid lithium that has been continuously flowed so as to have a constant thickness may be used as the target 5.

  The neutron moderator 6 decelerates the neutrons N generated at the target 5. The neutron moderator 6 is disposed between the target 5 and the irradiated object S in the course of the neutron N. The neutron moderator 6 reduces the energy of fast neutrons generated at the target 5 to generate low-speed and low-energy neutrons (thermal neutrons, epithermal neutrons, or cold neutrons).

  The collimator 7 collimates the neutrons N emitted from the neutron moderator 6 in a predetermined extraction direction. Hereinafter, the extraction direction in which the neutrons N are extracted from the neutron moderator 6 is referred to as a second direction D2. In the present embodiment, the second direction D2 is a side of the first direction D1. The irradiated object S is irradiated with neutrons N made parallel by the collimator 7 and emitted from the collimator 7.

  Next, an example of the neutron moderator 6 for neutron N according to the present embodiment will be described. FIG. 2 is an enlarged view showing a main part of the neutron irradiation apparatus 1. As shown in FIG. 2, the neutron moderator 6 is accommodated in the moderator accommodating portion 8. The moderator accommodating unit 8 reflects, scatters, or absorbs neutrons generated by the target 5.

  FIG. 3 is a perspective view showing an example of the neutron moderator 6 according to the present embodiment. As shown in FIGS. 2 and 3, the neutron moderator 6 has a main body 60. The main body 60 is formed using a material such as polyethylene containing hydrogen atoms, for example. In addition, as the main body 60, a configuration in which liquid hydrogen (liquefied hydrogen) composed of a single hydrogen atom is enclosed in a container may be used.

  The main body 60 has a plurality of protrusions 61. The protruding portion 61 is formed in a wedge shape or a triangular prism shape, for example, but is not limited thereto. The plurality of protrusions 61 are arranged, for example, side by side in the first direction D1 without a gap. The projecting portion 61 is disposed so as to project in the second direction D2. The protrusion 61 has a bottom surface 61a and inclined surfaces 61b and 61c. The bottom surface 61a is planar and is disposed at the rear end portion in the second direction D2. For example, the bottom surface 61a is disposed perpendicular to the second direction D2, but the present invention is not limited to this and may not be perpendicular.

  The inclined surfaces 61b and 61c are planar, for example, and are arranged so as to intersect with a virtual plane perpendicular to the second direction D2 at an angle within a predetermined range. Here, the bottom surface 61a will be described as an example of the virtual plane. The inclined surface 61b is arranged to intersect the bottom surface 61a at an angle α1. The inclined surface 61c is arranged to intersect the bottom surface 61a at an angle α2.

  The angles α1 and α2 are set within a predetermined range. In the present embodiment, the predetermined range is set to an angle of 60 ° to 85 °, for example, but is not limited thereto. The angle α1 and the angle α2 may be the same value or different values.

  The inclined surfaces 61b and 61c are disposed from the rear end in the second direction D2, that is, the bottom surface 61a, to the front end in the second direction D2, that is, the front end 61d. For this reason, the protruding portion 61 is gradually tapered from the bottom surface 61a to the tip portion 61d. The tip 61d of the protruding portion 61 has, for example, a pointed shape, but is not limited thereto, and may be formed in a rounded shape.

  Among the plurality of projecting portions 61, the projecting portion 61 arranged at the rearmost in the first direction D1 has an end surface 61e on the rear side in the first direction D1 arranged perpendicular to the first direction D1. In addition, the protrusion 61 that is disposed in the forefront in the first direction D1 has the end surface 61f on the front side in the first direction D1 disposed perpendicular to the first direction D1.

  In the main body 60, a groove 60 p is formed between the plurality of protrusions 61. The groove portion 60p is formed between the inclined surface 61b and the inclined surface 61c of the adjacent protruding portion 61. Therefore, in this embodiment, the inclined surfaces 61b and 61c are groove surfaces that form the groove portion 60p. The groove portion 60p is opened at the front end portion of the main body portion 60 in the second direction D2. Moreover, since the protrusion part 61 becomes a taper shape toward the front-end | tip part 61d as mentioned above, the groove part 60p becomes a shape which expanded toward the 2nd direction D2. The groove part 60p is formed from the front end part of the main body part 60 in the second direction D2 to the rear end part. Therefore, the main body part 60 has the same dimension (depth) of the groove part 60p in the second direction D2 as that of the whole main body part 60 in the second direction D2. In this case, the inclined surfaces 61b and 61c have shapes that are arranged so as to be alternately folded at the front end portion and the rear end portion in the second direction D2 of the main body portion 60.

  The main body 60 configured as described above has a surface area whose normal is perpendicular to the second direction D2 among the inclined surfaces 61b and 61c, which are groove surfaces forming the groove 60p, and the normal is the second direction. The sum of the surface area parallel to D2 is zero. In other words, the entire inclined surfaces 61b and 61c, which are groove surfaces, have shapes in which the normal line is inclined with respect to each of the surface perpendicular to the second direction D2 and the surface normal to the second direction D2. ing.

  The present inventor comprises a neutron moderator for decelerating neutrons, a main body formed using a material for decelerating neutrons, and a groove formed on the front end surface in the neutron extraction direction of the main body, The sum of the surface area of the surface where the main body forms the groove portion and whose normal is perpendicular to the extraction direction and the surface area of the surface whose normal is parallel to the extraction direction is 50% of the surface area of the entire groove surface It has been found that the number of low-speed neutrons extracted increases when

  The neutron moderator 6 according to the present embodiment is formed on the front end surface in the second direction D2 that is the direction in which the neutron N is taken out of the main body portion 60 and the main body portion 60 formed using a material that decelerates neutrons. Of the inclined surfaces 61b and 61c, which are groove surfaces that form the groove 60p, and the normal is the surface area of the surface perpendicular to the second direction D2, and the normal is the second direction. Since the sum of the surface area parallel to D2 is 0, it is 50% or less of the entire surface area of the groove surfaces (inclined surfaces 61b and 61c). Therefore, the neutron moderator 6 according to the present embodiment can increase the number of low-speed neutrons extracted.

  Further, the present inventor, in a neutron moderator that decelerates neutrons, a main body portion formed using a material that decelerates neutrons, and a groove portion formed on a front end surface in the neutron extraction direction of the main body portion, The groove portion has a portion that gradually widens in the take-out direction, and the main body portion has an area of a portion that gradually widens in the take-out direction in the groove surface constituting the groove portion in a plan view when viewed from the front in the take-out direction. It has been found that the number of low-speed neutrons extracted increases when is 50% or more of the entire groove surface area.

  The neutron moderator 6 according to the present embodiment is formed on the front end surface in the second direction D2 that is the direction in which the neutron N is taken out of the main body portion 60 and the main body portion 60 formed using a material that decelerates neutrons. An area of the portion corresponding to the inclined surfaces 61b and 61c in a plan view when the main body 60 is viewed from the front in the take-out direction. Is 100% of the entire area of the groove surface. Therefore, the neutron moderator 6 according to the present embodiment can increase the number of low-speed neutrons extracted.

  The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the configuration in which the groove portion 60p is formed from the front end portion to the rear end portion in the second direction D2 of the main body portion 60 has been described as an example, but the present invention is not limited to this.

  FIG. 4 is a diagram showing a neutron moderator 6A of the neutron irradiation apparatus 1A according to the modification. In the neutron moderator 6A, a groove 60q formed in the main body 60A is formed from the front end in the second direction D2 of the main body 60A to the middle of the rear. In the main body 60A, the depth L3 of the groove 60q is smaller than the dimension L1 in the second direction D2 of the entire main body 60A. The groove 60q has a shape that gradually expands in the second direction D2. In this case, the depth L3 is set to 50% or more with respect to the dimension L1 of the main body 60A. In the neutron moderator 6A, the depth L3 of the groove 60q is 50% or more with respect to the dimension L1 of the main body 60A. For this reason, the number of low-speed neutrons extracted can be increased more effectively.

  The main body portion 60A is arranged so that the inclined surfaces 62b and 62c of the projecting portion 62 do not reach the bottom surface 62a so that the front end portion in the second direction D2 and the rear halfway portion of the main body portion 60A are alternately folded. Shape. Therefore, the strength of the main body 60A is ensured because the plurality of protrusions 62 are reliably connected on the bottom surface 62a side.

  Moreover, FIG. 5 is a figure which shows the neutron moderator 6B of the neutron irradiation apparatus 1B which concerns on a modification. The neutron moderator 6B is similar to the above embodiment in that the groove 60r formed in the main body 60B is formed from the front end to the rear end in the second direction D2 of the main body 60B. It differs from the said embodiment by the point by which the protrusion parts 63 which fit are arrange | positioned at intervals.

  In this configuration, in the main body 60B, the depth L2 of the groove 60r is equal to the dimension L1 in the second direction D2 of the entire main body 60B. The groove 60r has a shape that gradually expands in the second direction D2. In the neutron moderator 6B, the depth L2 of the groove 60r is 50% or more with respect to the dimension L1 of the main body 60B. Therefore, the number of low-speed neutrons extracted can be increased more effectively. In addition, the neutron moderator 6B has a configuration in which the adjacent protrusions 63 are arranged with a space therebetween, so that the degree of design freedom is increased.

  Moreover, although the said embodiment demonstrated and demonstrated the structure in which the protrusion parts 61, 62, and 63 were formed in the wedge shape or the triangular prism shape, it does not limit to this. FIG. 6 shows a neutron moderator 6C according to a modification. As shown in FIG. 6, the neutron moderator 6 </ b> C has a plurality of protrusions 64 having a conical shape. The neutron moderator 6 </ b> C is configured to include a support portion 65 that supports the plurality of protrusions 64. A groove 60s is formed in the main body 60C. Since the plurality of projecting portions 64 have a tapered shape in the second direction D2, the groove portion 60s has a shape that gradually expands from the surface 65a of the support portion 65 in the second direction D2. The surface 65a of the support portion 65 is disposed perpendicular to the second direction D2. Therefore, the surface 65a is a surface whose normal is parallel to the second direction D2. In this configuration, the surface area of the surface 65a is equal to or less than 50% of the entire surface area of the groove surface, and the portion corresponding to the surface of the projecting portion 64 in a plan view when viewed from the front in the take-out direction. The diameter of the protrusion 64 and the dimension (height) in the protrusion direction are set so that the area is 50% or more with respect to the entire area of the groove surface. As a result, the number of low-speed neutrons extracted can be increased.

  FIG. 7 is a diagram showing a neutron moderator 6D according to a modification. As shown in FIG. 7, the neutron moderator 6 </ b> D has a plurality of protrusions 66 having a quadrangular pyramid shape. In the neutron moderator 6D, the plurality of protrusions 66 are arranged without a gap in a plane orthogonal to the second direction D2. A groove 60t is formed in the main body 60D. Since the plurality of protrusions 66 have a tapered shape in the second direction D2, the groove 60t has a shape that gradually expands in the second direction D2. In this configuration, in the main body 60D, the sum of the surface area of the surface whose normal is perpendicular to the second direction D2 and the surface area of the surface whose normal is parallel to the second direction D2 is 0, and the groove surface (protruding portion) 66 surface) is 50% or less of the entire surface area. Further, in a plan view when viewed from the take-out direction, the area of the portion corresponding to the surface of the protrusion 66 is 50% or more (for example, 100%) with respect to the area of the entire groove surface. Therefore, the neutron moderator 6D can increase the number of low-speed neutrons extracted.

  In the above embodiment, the case where the neutron extraction direction is the second direction D2 has been described as an example. However, the present invention is not limited to this. FIG. 8 is a diagram showing a neutron moderator 6E (neutron irradiation apparatus 1E) according to a modification. Like the neutron irradiation apparatus 1E shown in FIG. 8, the structure which made the extraction direction of the neutron the 1st direction D1 may be sufficient. In this configuration, the projecting portion 61 is tapered toward the first direction D1, which is the neutron extraction direction. Moreover, the neutron irradiation apparatus 1E has a configuration in which the moderator accommodating portion 8E has a take-out portion on the first direction D1 side. With this configuration, the neutron NE extracted in the first direction D1 includes the fast neutrons, but the number of low-speed neutrons extracted can be increased.

  Moreover, in the said embodiment, although the structure which has the dimension of the protrusion part about the neutron extraction direction in the main-body part of the neutron moderator was mentioned as an example, it demonstrated, It does not limit to this. FIG. 9 is a diagram showing a neutron moderator 6F according to a modification. Like the neutron moderator 6F shown in FIG. 9, the structure which has the 1st protrusion part 67a and the 2nd protrusion part 67b from which the dimension about the extraction direction (illustrated as 2nd direction D2) differs may be sufficient. In this case, groove portions 60v and 60w having different depths in the second direction D2 are formed. Each of the groove portions 60v and 60w has a shape that spreads in the second direction D2. In the neutron moderator 6F, in the main body 60F, the sum of the surface area of the surface whose normal is perpendicular to the second direction D2 and the surface area of the surface whose normal is parallel to the second direction D2 is 0, and the entire groove surface The surface area is 50% or less. Further, in a plan view when viewed from the take-out direction, the area of the portion corresponding to the surface of the first protrusion 67a and the second protrusion 67b is 50% or more (for example, 100%) with respect to the entire groove surface. ). Therefore, the neutron moderator 6F can increase the number of low-speed neutrons extracted.

  Moreover, in the said embodiment, although the structure which a protrusion part was formed in the inclined surface form was mentioned as an example, it demonstrated, It does not limit to this. FIG. 10 is a diagram showing a neutron moderator 6G according to a modification. In the neutron moderator 6G shown in FIG. 10, the protrusion 68 has a first surface 68a perpendicular to the second direction D2 and a second surface 68b perpendicular to the first surface 68a.

  The protrusion 68 is formed in a minute step shape by alternately arranging the first surface 68a and the second surface 68b in the second direction D2. In the main body 60G, the groove surface of the groove 60x is configured by the first surface 68a and the second surface 68b. Note that FIG. 10 schematically shows the first surface 68a and the second surface 68b with dimensions larger than the actual size in order to make it easy to distinguish the figure, but actually, the first surface 68a and the second surface 68a. 68b is constituted by a minute flat surface or curved surface having a size that cannot be discriminated with the naked eye, for example. In addition, the first surface 68a and the second surface 68b can be discriminated with the naked eye, but may be configured as a flat surface or a curved surface with dimensions such that the overall shape of the protrusion 68 is tapered in the second direction D2.

  In this configuration, the first surface 68a is a surface whose normal is perpendicular to the second direction D2, and the second surface 68b is a surface whose normal is parallel to the second direction D2. For this reason, microscopically, the sum of the surface area of the surface whose normal is perpendicular to the second direction D2 and the surface area of the surface whose normal is parallel to the second direction D2 is the entire groove surface constituting the groove portion 60x. 100% of the surface area.

  However, each of the first surface 68a and the second surface 68b is a minute plane, and as a whole structure of the main body portion 60G, the groove portion 60x is macroscopically shaped to expand in the second direction D2. It is the same as each said structure. Accordingly, as shown in FIG. 10, the shape in which the minute first surfaces 68 a and the second surfaces 68 b are alternately arranged so that the groove portion 60 x gradually spreads in the second direction D <b> 2 as a whole is as the entire groove surface. From a macroscopic viewpoint, it can be regarded as a “portion that gradually expands in the take-out direction”. In this case, in the main body 60G, the area of the portion corresponding to the first surface 68a is 50% or more of the entire groove surface in a plan view when viewed from the take-out direction. Therefore, the neutron moderator 6G according to the present embodiment can increase the number of low-speed neutrons extracted.

1, 1A, 1B, 1E Neutron irradiation device 2 Acceleration device 3 Adjustment device 4 Scanning device 5 Target 6, 6A, 6B, 6C, 6D, 6E, 6F, 6G Neutron moderator 7 Collimator 8, 8E Moderator housing 60, 60A, 60B, 60C, 60D, 60E, 60F, 60G Main body portion 60p, 60q, 60r, 60s, 60t, 60v, 60w, 60x Groove portions 61, 62, 63, 64, 66, 68 Protruding portions 61a, 62a Bottom surface 61b, 61c, 62b, 62c Inclined surface 61d End portion 61e, 61f End surface 65 Support portion 65a Surface 67a First protrusion 67b Second protrusion 68a First surface 68b Second surface α1, α2 Angle D1 First direction D2 Second direction L1 Dimensions N, NE Neutron P Charged particle S Object to be irradiated

Claims (9)

A neutron moderator that decelerates neutrons,
A main body formed using a material for decelerating the neutrons;
A groove formed on the front end surface in the neutron extraction direction of the main body, and
Of the groove surfaces forming the groove portion, the main body portion has a sum of a surface area of a surface whose normal is perpendicular to the extraction direction and a surface area of a surface whose normal is parallel to the extraction direction. A neutron moderator that has a surface area of 50% or less. A neutron moderator that decelerates neutrons,
A main body formed using a material for decelerating the neutrons;
A groove formed on the front end surface in the neutron extraction direction of the main body, and
The groove has a portion that gradually expands in the take-out direction,
In the plan view when viewed from the front in the take-out direction, the main body portion has an area of a portion that gradually expands in the take-out direction of the groove surface constituting the groove portion is 50% of the area of the entire groove surface. This is the neutron moderator.   3. The neutron moderator according to claim 1, wherein the main body portion has a size of the groove portion in the take-out direction of 50% or more with respect to a size in the take-out direction of the entire main body portion.   The neutron moderator according to any one of claims 1 to 3, wherein the main body portion is arranged such that the groove surface intersects with a virtual plane perpendicular to the take-out direction at an angle within a predetermined range.   The neutron moderator according to claim 4, wherein the predetermined range is an angle of 60 ° to 85 °. The main body has a plurality of protrusions formed in a tapered shape toward the take-out direction,
The said groove part is a neutron moderator as described in any one of Claims 1-5 formed between the said some protrusion parts.   The neutron moderator according to claim 6, wherein the protrusion has a wedge shape or a cone shape. An accelerator that accelerates and ejects charged particles;
A target that is irradiated with the charged particles emitted from the accelerator and generates neutrons;
The neutron moderator according to any one of claims 1 to 7, wherein the neutron generated at the target is decelerated and irradiated in the extraction direction;
A neutron irradiation apparatus comprising:   The neutron irradiation apparatus according to claim 8, wherein the extraction direction is lateral to an irradiation direction of the charged particles irradiated to the target.

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