2020 Impact factor 3.043
Hadrons and Nuclei
Eur. Phys. J. A 16, 17-19 (2003)
DOI: 10.1140/epja/i2002-10112-y

Short Note

Identification of the new isotope $\chem{^{241}Bk}$

M. 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

asai@tandem.tokai.jaeri.go.jp

(Received: 14 October 2002 / Published online: 17 January 2003)

Abstract
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 $\gamma$ transitions were attributed to the EC decay of 241Bk through X- $\gamma$ coincidences. The half-life of 241Bk was determined to be $4.6 \pm 0.4$ min which is 1/2-1/4 of that of theoretical predictions. The half-life value and the observed $\gamma$ transitions can be consistently explained as a consequence of the allowed EC transition of $\pi 7/2^{+}[633] \rightarrow \nu 7/2^{+}[624]$.

PACS
23.20.Lv - Gamma transitions and level energies.
23.40.-s - Beta decay; double beta decay; electron and muon capture.
27.90.+b - $A \geq 220$ .

© Società Italiana di Fisica, Springer-Verlag 2003