Strong enhancement of level densities in the crossover from spherical to deformed neodymium isotopes

Understanding the evolution of level densities in crossover from spherical to well-deformed nuclei has been a long-standing problem nuclear physics. We measure for chain neodymium isotopes $^{142,144-151}$Nd which exhibit such crossover. These results represent date most complete data set an isotopic between neutron shell-closure and towards mid-shell. observe strong increase along with overall by factor $\approx 170$ at excitation energy 7.5 MeV saturation around mass 150. Level calculated shell model Monte Carlo (SMMC) are excellent agreement these experimental results. Based on our theoretical findings, we offer explanation observed dependence terms intrinsic single-particle density collective enhancement.