Two-Quasiparticle Excitation in ¹⁴⁶Eu

The level structure of the odd-odd nucleus ¹⁴⁶₆₃Eu₈₃ should be understandable from the comparison with the neighbouring odd nuclei with Z=63 or N=83. By the radioactive β⁺-decay of the 0⁺ ground state of ¹⁴⁶Gd mainly the low-spin states of ¹⁴⁶Eu are populated. The high angular momentum transfer of the compound nuclear reaction with charged particles offers the possibility of exciting high spin states. Remaev et al. /1/ made use of the (p, 2n) reaction and reported on the existence of an isomeric level with T_½=240±10_μs. They found delayed gamma transitions of 240, 280, 360, 390 and 480 keV energy, but no decay scheme could be established. A measurement /2/ of the K/L ratio of the 276keV transition resulted in the value 6.4±1.5. This value is compatible only with a low multipolarity of this transition, which, therefore, cannot be the isometric transition. In order to establish a decay scheme of the 240_μs isomeric state in ¹⁴⁶Eu we have carried out in-beam experiments at the U-300 Heavy Ion Cyclotron.