Alpha-gamma decay studies of 255No

The decay of 255No was investigated by means of α-γ spectroscopy. The isotope was produced in the reactions 208Pb(48Ca, n)255No, \(\mathrm{{}^{209}Bi({}^{48}Ca,2n){}^{255}Lr \ {}^{\ensuremath \mathit{EC}}_{\rightarrow}\ {}^{255}No}\), and $238U(22Ne, 5n)255No$. Levels of the daughter nucleus 251Fm were assigned by α-γ coincidence measurements and on the basis of systematics. Level energies were determined precisely using measured γ-rays. The results are compared with the known level schemes of the lighter \(\ensuremath N=151\) isotones 247Cm and 249Cf as well as with data for 253No.