Reflection asymmetric states in 146 Nd

Available as short communication only. The 146 Nd nucleus was studied through the reaction 136 Xe(13 C,3 nγ) 146 Nd, at a beam-energy of 54 MeV. The experiment was carried out at the Niels Bohr Institute, Denmark, with the NORDBALL detector array and a cryogenic target developed at the Kernfysisch Versneller Instituut, University of Groningen. These data led to a decay scheme which substantially improve the previous existing information. We established the existence of five bands containing stretched quadrupole transitions. Among them there are two bands of opposite parity (the positive parity ground state band and the negative parity band build on the level E*=1189.6 keV, Jπ=3-) linked by strong interband dipole transitions. In the formalism for reflection asymmetric nuclei, these two opposite parity bands correspond to a simplex quantum number s=+1. An important finding of the present work is the first observation of a similar structure build on the top of the level E*=3245.5 keV, Jπ=10-, corresponding possibly to the simplex quantum number s=-1. From the analysis of the energies and B(E1)/B(E2) ratios we found experimental evidence for the octupole vibrational behavior of the nucleus 146 Nd for the low spin range (J≤8) and for its octupole softness in the medium spin range (J≤16). Averaging the branching ratios for low (J≤8) and medium spins (9≤J≤16) in the octupole deformed bands (s=±1) we obtained for the intrinsic dipole moments D0low=0.19(1) e fm and D0med=0.30(1) e fm, respectively. These values are the largest ones observed in this region of nuclei. (Author) 1 Fig., 2 Refs