An improved simple model for the α decay half-lives

In the present work, taking the α particle preformation probabilities Pα from Xu et al. [Xu and Ren, Nucl. Phys. A 760,303, 2005], which were extracted by fitting the experimental half-lives of α decay, based on a phenomenological harmonic oscillator potential model (HOPM) [Bayrak, J Phys G 47:025102, 2020], refitting 178 α decay half-lives of even-even nuclei taken from the latest nuclear property table NUBASE2020, we obtain the only one adjustable parameter V0 = 162.6MeV in HOPM i.e. the depth of nuclear potential, while the corresponding root-mean-square (rms) deviation is σ = 0.322. Furthermore, for considering the contribution of centrifugal potential to unfavored α decay half-lives, adding a new term d(l(l+ 1))^0.5 (d and l are the adjustable parameter and orbital angular momentum taken away by emitted α particle) to the logarithmic form of favored α decay half-lives under the HOPM framework, we propose an improved simple model (ISM) for calculating favored and unfavored α decay half-lives. Fitting the experimental half-lives of 205 unfavored α decay, we obtain d = 0.381. Using the improved simple model, the unfavored α decay half-lives of 128 odd-A and 77 odd-odd nuclei are calculated, the results are improved by 54.2% and 53.6%, respectively, compared with HOPM. In addition, we extend ISM to predict the α decay half-lives of 144 nuclei with Z = 117,118,119 and 120. For comparison, the improved model with eight parameters (DUR) proposed by Deng et al. [Deng, Phys. Rev. C 101: 034307, 2020] and the modified universal decay law (MUDL) put forward by Soylu et al. [Soylu, Nucl. Phys. A 1013: 122221, 2021] are also used. The predictions of these models and/or formulas are basically consistent with each other.