Decay Study of $^{257}$Rf

Excited states in heavy odd-even nuclei allow for the measurement of single-particle energies of orbitals playing a major role in the shell stabilization of superheavy nuclei. In this work we report on decay spectroscopy of $^{257}$Rf. The excited states of $^{257}$Rf and its daughter $^{253}$No can provide information on the single-particle structure near the deformed neutron shell N=152. $^{257}$Rf was produced in the fusion-evaporation reaction $^ {50}$Ti + $^{208}$Pb at the Argonne Tandem Linac Accelerator System, using the Fragment Mass Analyzer. The mass/charge ratio of the recoils was used for the identification of the evaporation residues. The $\alpha$ decays and internal conversion electrons from $^{257}$Rf or its decay products were recorded in a Double-sided Silicon Strip Detector and the gamma rays coincident with the charged particles were detected in four HPGe detectors. The results are compared with those of N=153 isotones and analyzed in a theoretical Macroscopic- Microscopic framework using the universal Woods-Saxon single- particle potential. These data can test the validity of this potential for superheavy nuclei. This work was supported by the U.S. DOE under contract No. DE-AC02-06CH11357 and DE-FG02- 91ER40609.