Alpha decay characteristics of 134 even–even, 243 odd-A and 68 odd–odd heavy nuclei are investigated using the improved Coulomb and proximity potential model (CPPM). The CPPM is improved by introducing an empirical diffuseness parameter (b) that depends upon the isospin and reduced mass of the parent nucleus in the expression for the proximity potential. The predictions of the CPPM with \(b = 1\) fm and that with the calculated values of the diffuseness parameter are compared with the experimental values. Improvement in the predictive power of the CPPM is observed when the empirical diffuseness parameter is included in the calculations. The experimental alpha decay half-lives are well reproduced. The barrier penetrability and alpha preformation factor are also estimated through the CPPM calculations. The importance of the use of an accurate value of the surface diffuseness in the alpha and cluster decay half-life calculations became evident from our study. The calculations are also performed by using the Viola–Seaborg formula and the Horoi formula, two most successful empirical formulae. The lowest standard deviation is obtained for the CPPM calculations with the empirical diffuseness parameter.
