  We present a probable experimental signature of collective enhancement in the
nuclear level density (NLD) by measuring the neutron and the giant dipole
resonance (GDR) $\gamma$ rays emitted from the rare earth $^{169}$Tm compound
nucleus populated at 26.1 MeV excitation energy. An enhanced yield is observed
in both neutron and $\gamma$ ray spectra corresponding to the same excitation
energy in the daughter nuclei. The enhancement could only be reproduced by
including a collective enhancement factor in the Fermi gas model of NLD to
explain the neutron and GDR spectra simultaneously. The experimental results
show that the relative enhancement factor is of the order of 10 and the fadeout
occurs at $\sim$ 14 MeV excitation energy, much before the commonly accepted
transition from deformed to spherical shape. We also explain how the collective
enhancement contribution changes the inverse level density parameter ($k$) from
8 to 9.5 MeV observed recently in several deformed nuclei.

Nuclear Experiment