**Author details**

Masaru Kato

*Department of Mathematical Sciences, Osaka Prefecture University1-1, Gakuencho, Sakai, Osaka, Japan* 

Takekazu Ishida

*Department of Physics and Electronics, Osaka Prefecture University, 1-1, Gakuencho, Sakai, Osaka, Japan* 

Tomio Koyama *Institute of Material Sciences, Tohoku University, Sendai, Japan* 

Masahiko Machida *CCSE, Japan Atomic Energy Agency, Tokyo, Japan* 
