X-ray irradiation effect of double walled carbon nanotube Toshiya Murakami, Kunihito Asai, Yuki Yamamoto, Kenji Kisoda and Chihiro Itoh Eur. Phys. J. B, 86 4 (2013) 187 Published online: 24 April 2013 DOI: 10.1140/epjb/e2013-30591-8