[1I08-12] Neutron Beam

[1I08] Study on a Japanese Sword by Using Neutrons and Muons

*Yoshiaki Kiyanagi^1,8, Kazuhiko Ninomiya², Kenya Kubo³, Kenichi Watanabe⁴, Kenichi Oikawa⁵, Motonobu Tampo⁶, Yoshihiro Matsumoto⁷, Yasuhiro Miyake⁶, Takenao Shinohara⁵ (1. J-NOP, 2. Osaka Univ., 3. ICU, 4. Kyushu Univ., 5. JAEA, 6. KEK, 7. CROSS, 8. Hokkaido Univ.)

Keywords:Neutron, Muon, Japanese sword, Internal structure, Carbon content, Crystallographic structure

Japanese swords are a valuable metal cultural heritage, which have a history more than 1000 years. Their metallurgical characteristics are important since they relate to smithing methods. A systematic study by using non-destructive methods has been desired. Neutron and muon are very effective. Neutron Bragg edge transmission gives crystallographic information, neutron CT reveals internal structure, and muon gives information on carbon content. We studied a Bizen sword by using these methods. CT implied a layered structure. Crystallite size distribution suggested it related to the layered structure. Carbon contents were 0.38% near the edge, 0.20% around center and 0.15% near backside. The results suggest that soft steel (shingane) with low carbon content existed near the surface around the backside.