Patent Number: 
Section: claims

1. An apparatus for controlling a neutron beam, comprising a plurality of columnar prisms that are made of a material having a refractive index of less than 1 for a neutron beam, and are arranged so as to be multi-layered. 2. An apparatus for controlling a neutron beam according to claim 1, wherein the columnar prisms 1 each have an approximately right-triangle-shaped section, and are three-dimensionally multi-layered such that respective surfaces of the columnar prisms are in parallel to one another. 3. An apparatus for controlling a neutron beam according to claim 2, wherein oblique surfaces of the multi-layered columnar prisms are in parallel to one another, and face in the same direction so as to approximately form a triangular prism as a whole. 4. An apparatus for controlling a neutron beam according to claim 3, comprising a plurality of said triangular prisms arranged such that oblique surfaces respectively constituting the triangular prism cross each other. 5. An apparatus for controlling a neutron beam according to claim 1, wherein the columnar prisms 1 each have an approximately right-triangle-shaped section,the apparatus for controlling the neutron beam comprises a plurality of horizontal prism plates each of which includes the columnar prisms horizontally arranged such that respective surfaces of the columnar prisms are in parallel to one another, andthe plurality of horizontal prism plates are vertically multi-layered so as to be horizontally turned alternately by 90 degrees. 6. An apparatus for controlling a neutron beam according to claim 1, comprising a positioning member that sets the plurality of columnar prisms at predetermined positions, respectively. 7. A method for manufacturing a neutron beam controlling apparatus, comprising:forming a plurality of columnar prisms that are made of a material having a refractive index of less than 1 for a neutron beam, and each have an approximately right-triangle-shaped section; andthree-dimensionally multi-layering the plurality of columnar prisms such that respective surfaces of the columnar prisms are in parallel to one another. 8. A method for manufacturing a neutron beam controlling apparatus according to claim 7, wherein the forming of the plurality of columnar prisms is performed by any of molding, extruding, cutting, grinding, whetting or any combination thereof. 9. A method for manufacturing a neutron beam controlling apparatus according to claim 7, wherein forming the plurality of prisms comprising:making stick-shaped members of said material;setting the stick-shaped members in a plurality of grooves formed on a jig, the grooves having the same shape; andflattening upper surfaces of the grooves at the same time. 10. A method for manufacturing a neutron beam controlling apparatus according to claim 9, wherein the flattening of the upper surfaces of the grooves is performed by ELID grinding. 11. A method for manufacturing a neutron beam controlling apparatus according to claim 9, wherein the flattening of the upper surfaces of the grooves is performed by a straight grinding wheel, a cup grinding wheel or a lap.