Speaker
Dr
Ichiro Nishinaka
(Japan Atomic Energy Agency, Japan)
Description
An alpha radioactive nuclide 211At with a half-life of 7.2 h is a prospective candidate for utilization in targeted alpha radiotherapy. In a general way, 211At is produced through bombardment of a bismuth target with 28 MeV helium ions in the 209Bi(alpha,2n)211At reaction because of the high yield required for therapeutic purpose [1]. However, the nuclear reactions using lithium ion beams, 6,7Li+Pb and 6,7Li+209Bi, provide the possible production routes of 211At. Excitation functions have been extensively measured for the 6,7Li+ 209Bi reactions to study the reaction mechanism involving complete fusion and breakup reaction of weakly bounded nuclei 6,7Li [2-4]. For 7Li+natPb, however, only reports on production of astatine isotopes 207-210At have been available for radiotherapy [5]. Therefore, we have measured excitation functions of 208-211At in the reaction of 29-57 MeV 7Li+natPb at the tandem accelerator of JAEA-Tokai. The cross sections of radioactive products were determined by alpha- and gamma-ray spectrometry. The cross sections of 211At below 45 MeV are large compared with those of the other astatine isotopes 208-210At. The experimental excitation functions of astatine isotopes have been compared with a statistical calculation to study the reaction mechanism. Besides, a chemical separation of carrier-free radioactive astatine isotopes from an irradiated target has been studied with a dry-chemistry method. Details will be shown in the presentation.
References
[1] S. Lindergren, T. Bäck, H. J. Jensen, Appl. Radiat. Isot., 55 (2001) 157-160; S. Lindegren et al., J. Nucl. Med., 49 (2008) 1537-1545.
[2] H. Freiesleven, H. C. Britt, J. Birkelund, and J. R. Huizenga, Phys. Rev. C, 10 (1974) 245-249.
[3] M. Dasgupta et al., Phys. Rev. C, 66 (2002) 04602-1-4; M. Dasgupta et al., Phys. Rev. C, 70 (2004) 024606-1-20.
[4] Yu. E. Penionzhkevich et al., J. Phys. G, 36 (2009) 025104-1-12.
[5] K. Roy, and S. Lahiri, Appl. Radiat. Isot., 55 (2008) 571-576; M. Maiti and S. Lahiri, Phys. Rev. C84 (2011) 067601.
Primary author
Dr
Ichiro Nishinaka
(Japan Atomic Energy Agency, Japan)
Co-authors
Akihiko YOKOYAMA
(Kanazawa University)
Mr
Eita Maeda
(Kanazawa University)
Dr
Hiroyuki Makii
(Japan Atomic Energy Agency)
Dr
Kazuyuki Hashimoto
(Japan Atomic Energy Agency)
Dr
Kohshin Washiyama
(Kanazawa University)
Mr
Norihiro Yamada
(Kanazawa University)
Dr
Noriko Ishioka
(Japan Atomic Energy Agency)
Prof.
Ryohei Amano
(Kanazawa University)
Dr
Shigeki Watanabe
(Japan Atomic Energy Agency)
