The entry distribution in angular momentum and excitation energy for the formation of ${}^{254}\mathrm{No}$ has been measured after the ${}^{208}\mathrm{Pb}{(}^{48}\mathrm{Ca},2n)$ reaction at 215 and 219 MeV. This nucleus is populated up to spin $22ħ$ and excitation energy $\gtrsim 6\mathrm{MeV}$ above the yrast line, with the half-maximum points of the energy distributions at $\sim 5\mathrm{MeV}$ for spins between $12ħ$ and $22ħ$. This suggests that the fission barrier is $\gtrsim 5\mathrm{MeV}$ and that the shell-correction energy persists to high spin.

• Received 3 January 2000

DOI:https://doi.org/10.1103/PhysRevLett.84.3542