Nuclear level-density parameters of nuclei in the Z∼70 and A∼180 mid-shell regions

α-particle evaporation energy spectra have been measured as a function of γ-ray fold for various target-projectile systems leading to residual nuclei in the range of Z∼70 and A∼180 with excitation energy of 30-40 MeV. The inverse level-density parameter K was determined for various nuclei by comparing the high-energy part of the α-particle evaporation spectra with PACE2 predictions. It is observed that the inverse level-density parameter remains constant for all systems studied in this work within statistical errors in the angular momentum range of 15-30 (ℎ/2π). The fold-gated α-particle energy spectra in these systems are well reproduced by the PACE2 code with a level-density parameter value of A/(8.2±1.1) MeV-1.