Identification of the new isotopeM. Asai1, K. Tsukada1, S. Ichikawa1, M. Sakama2, H. Haba3, Y. Nagame1, I. Nishinaka1, K. Akiyama1, A. Toyoshima1, T. Kaneko1, Y. Oura4, Y. Kojima5 and M. Shibata6
1 Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195, Japan
2 Department of Radiologic Science and Engineering, University of Tokushima, Tokushima 770-8509, Japan
3 Radioisotope Technology Division, Cyclotron Center, RIKEN, Wako, Saitama 351-0198, Japan
4 Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
5 Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
6 Facility for Nuclear Materials, Nagoya University, Nagoya 464-8603, Japan
(Received: 14 October 2002 / Published online: 17 January 2003)
A new neutron-deficient berkelium isotope 241Bk produced in the 239Pu( 6Li, 4 n) reaction has been identified using a gas-jet coupled on-line isotope separator. Cm K and L X-rays associated with the EC decay of 241Bk were observed in the mass-241 fraction, and three transitions were attributed to the EC decay of 241Bk through X- coincidences. The half-life of 241Bk was determined to be min which is 1/2-1/4 of that of theoretical predictions. The half-life value and the observed transitions can be consistently explained as a consequence of the allowed EC transition of .
23.20.Lv - Gamma transitions and level energies.
23.40.-s - Beta decay; double beta decay; electron and muon capture.
27.90.+b - .
© Società Italiana di Fisica, Springer-Verlag 2003