In-beam spectroscopy with intense ion beams: Evidence for a rotational structure in 246Fm

The rotational structure of 246Fm has been investigated using in-beam γ -ray spectroscopic techniques. The experiment was performed using the JUROGAMII germanium detector array coupled to the gas-filled recoil ion transport unit (RITU) and the gamma recoil electron alpha tagging (GREAT) focal plane detection system. Nuclei of 246Fm were produced using a 186 MeV beam of 40Ar impinging on a 208Pb target. The JUROGAMII array was fully instrumented with Tracking Numerical Treatment 2 Dubna (TNT2D) digital acquisition cards. The use of digital electronics and a rotating target allowed for unprecedented beam intensities of up to 71 particle-nanoamperes for prompt γ -ray spectroscopy at a level of approximately 11 nb. With all these major experimental advances a rotational band is observed in 246Fm.