Neutrons are a valuable probe for the study of materials science and bioscience for two major reasons. They penetrate material easily, since they have no electric charge, and they scatter strongly from light elements such as hydrogen atoms by means of nuclear interactions. High-flux neutron beams for materials research are available at research reactors and accelerator-based facilities, but the scope of their research is currently limited by their relatively low intensity.
In collaboration with RIKEN, we are developing a magnetic neutron lens to increase effective beam intensities within the research program "Development and Application of Neutron Optics," supported by the Special Coordination Fund for Promoting the Ministry of Education of the Japanese Government. The magnetic lens is a sextupole magnet in which six magnetic poles are placed around an annular aperture. The neutrons are refracted along the gradient of magnetic field strength and focused onto the magnet axis through the interaction between neutron magnetic dipole moments and the sextupole magnetic field. We have successfully developed a strong magnetic lens with an aperture as large as 50 mm by employing a superconducting sextupole magnet (Fig. 7-10). We have confirmed that the magnetic lens has sufficient power to focus the cold neutron beam from the research reactor JRR-3, as shown in Figs. 7-11 and 7-12. |
