Experiments on synthesis of the heaviest elements at RIKEN
K. Morimoto
Nishina Center for Accelerator Based Science
RIKEN (The Institute of Physical and Chemical Research), Japan
In the Institute of Physical and Chemical Research (RIKEN), using high intensity heavy
ion beams from RIKEN Linear Accelerator, productions and decays of isotopes of the
heaviest elements have been investigated by using a gas-filled recoil separator, GARIS.
The isotopes studied were
208
58
Pb( Fe, n),
208
265
Hs,
64
271
Pb( Ni, n)[1],
Ds,
209
272
Rg,
277
112, and
64
Bi( Ni, n)[2],
277
112), and 2 (
113, produced by reactions
208
70
209
Pb( Zn, n),
respectively. The numbers of atoms observed were 10 (
(
278
265
Hs), 14 (
70
Bi( Zn, n)[3],
271
Ds), 14 (
272
Rg), 2
278
113). Based on the observed decay chains consisted of consecutive
alpha decays connected to the previously known alpha decays or spontaneous fissions,
assignments of the initially produced isotopes were done. Our data with the atomic
number from 108 to 112, agree well with the data previously taken. The production
cross section of the isotope
278
113 of the 113th element have leached around 30 fb
which shows simple decrease of the cross section with the increase of the atomic
number. The isotopes were produced, for the first time in the 1n evaporation channel
from heavy-ion induced complete fusion reaction.
References
[1] K. Morita et al., Eur. Phys. J. A21, 257 (2004).
[2] K. Morita et al., J. Phys. Soc. Jpn. 73, 1738 (2004).
[3] K. Morita et al., J. Phys. Soc. Jpn. 73, 2593 (2004).