Excitation function for the production of Bh262 (Z=107) in the odd-Z-projectile reaction Pb208(Mn55, n)

The excitation function for production of Bh262 in the odd-Z-projectile reaction Pb208(Mn55, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from Bh262 and 2 decay chains originating from Bh261 were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540-150+180 pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than five times larger than that expected based on previously reported results for production of Bh262 in the analogous even-Z-projectile reaction Bi209(Cr54, n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the optimum energy rule proposed by Świa̧tecki, Siwek- Wilczyńska, and Wilczyński.