Analytic expressions for alpha-decay half-lives and potential barriers (original) (raw)
Related papers
Systematical calculation of α decay half-lives with a generalized liquid drop model
A systematic calculation of α decay half-lives is presented for even-even nuclei between Te and Z = 118 isotopes. The potential energy governing α decay has been determined within a liquid drop model including proximity effects between the α particle and the daughter nucleus and taking into account the experimental Q value. The α decay half-lives have been deduced from the WKB barrier penetration probability. The α decay half-lives obtained agree reasonably well with the experimental data.
ANALYTIC RELATIONS FOR PARTIAL ALPHA DECAY HALF-LIVES AND BARRIER HEIGHTS AND POSITIONS
Int. J. Mod. Phys. E 20 1030, 2011
From an adjustment on a recent selected data set of partial α-decay half-lives of 344 ground state to ground state transitions, analytic formulae are proposed depending on the angular momentum of the α particle. In particular, an expression allows to reproduce precisely the partial α-decay half-lives of even-even heavy nuclei and, then, to predict accurately the partial α-decay half-lives of other very heavy elements from the experimental or predicted Qα. Simple expressions are also provided to calculate the potential barrier radius and height.
International Journal of Modern Physics E
The α decay potential barriers are determined in the cluster-like shape path within a generalized liquid drop model including the proximity effects between the α particle and the daughter nucleus and adjusted to reproduce the experimental Qα. The α emission half-lives are determined within the WKB penetration probability. Calculations using previously proposed formulae depending only on the mass and charge of the alpha emitter and Qα are also compared with new experimental alpha-decay half-lives. The agreement allows to provide predictions for the α decay half-lives of other still unknown superheavy nuclei using the Qα determined from the 2003 atomic mass evaluation of Audi, Wapstra and Thibault.
Systematic study on α-decay half-lives: a new dependency of effective sharp radius on α-decay energy
Eur. Phys. J. A, 2021
Within the framework of the proximity formalism, we present a systematic study to analyze the effects of the α-decay energy through the effective sharp radius parameter on the α-decay half-lives of 227 nuclei in the range 61 ≤ Z ≤ 99. Wentzel-Kramers-Brillouin (WKB) calculations with the proximity potential Zhang 2013 are carried out to obtain the theoretical values of the α-decay half-lives. In this work, we introduce a new Q α-dependent (QD) form of the effective sharp radius which significantly reduces the standard deviation of estimated half-lives using the Zhang 2013 model in comparison with the corresponding experimental data in our selected mass range. We evaluate the validity of this simple formula using the Geiger-Nuttall (G-N) plots and semi-empirical formulas. The modified form of the Zhang 2013 model is also found to work well in α-decay studies of superheavy nuclei (SHN) with Z = 117 − 120. Our results reveal that the calculated half-lives for the use of new proposed form of the effective sharp radius in the proximity potential can reproduce the closed-shell effects at neutron magic number N = 126 and N = 184.
Effective liquid drop description for alpha decay of atomic nuclei
Journal of Physics G: Nuclear and Particle Physics, 1998
Alpha decay half-lives are presented in the framework of an effective liquid drop model for different combination of mass transfer descriptions and inertia coefficients. Calculated half-life-values for ground-state to ground-state favoured alpha transitions are compared with available, updated experimental data. Results have shown that the present model is very suitable to treat the alpha decay process on equal foot as cluster radioactivity and cold fission processes. Better agreement with the data is found when the subset of even-even alpha emitters are considered in the calculation.
An improved empirical formula for α decay half-lives
Physical Review C 101n034307 , 2020
The Royer formulas are often used to calculate the decay half-lives [G. Royer, J. Phys. G 26, 1149 (2000), Nucl. Phys. A 848, 279 (2010)]. In recent years, the number of experimental data on decay has increased and these formulas have been examined again. They describe precisely the favored decays. For unfavoured decays, they are less accurate and important deviations may occur between the calculations and experimental data. The underlying physics of this phenomenon has been revealed and an improved formula with only 8 parameters is proposed. This formula takes into account both the blocking e ect of unpaired nucleons and the contribution of centrifugal potential. Compared with the original formulas and other improvements, our new formula is more simple to use and more accurate. Encouraged by this, the decay half-lives of even-even nuclei and odd-A nuclei with Z = 117, 118, 119 and 120 are predicted using our improved formula and the Universal Decay Law [C. Qi et al., Phys. Rev. Lett. 103, 072501 (2009)] with the extrapolated Q of WS3+ mass model [N. Wang and M. Liu, Phys. Rev. C 84, 051303(R) (2011)]. The predictions of these two formulas are consistent. However, for 293Ts and 294Og, predicted decay half-lives by our improved formula show better agreement with experimental data, indicating that predictions by our improved formula are more reliable and useful for future new superheavy elements and isotopes experimental assignments and identi cations. Meanwhile, the features of predicted decay energy and half-lives imply that N = 184 is the next neutron magic number after N = 126.
Physical Review C, 2007
Theoretical α-decay half-lives of the heaviest odd-Z nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time. Predictions are provided for the α decay half-lives of other superheavy nuclei within the GLDM and VSS approaches using the extrapolated Audi's recent Qα, which may be used for future experimental assignment and identification.
Entrance channels and alpha decay half-lives of the heaviest elements
Nuclear Physics A, 2004
The barriers standing against the formation of superheavy elements and their consecutive α decay have been determined in the quasimolecular shape path within a Generalized Liquid Drop Model including the proximity effects between nucleons in a neck, the mass and charge asymmetry, a precise nuclear radius and the shell effects given by the Droplet Model. For moderately asymmetric reactions doublehump potential barriers stand and fast fission of compact shapes in the outer well is possible. Very asymmetric reactions lead to one hump barriers which can be passed only with a high energy relatively to the superheavy element energy. Then, only the emission of several neutrons or an α particle can allow to reach an eventual ground state. For almost symmetric heavy-ion reactions, there is no more external well and the inner barrier is higher than the outer one. Predictions for partial α decay half-lives are given.
Atomic Data and Nuclear Data Tables, 2002
Half-life values of spontaneous nuclear decay processes are presented in the framework of the effective liquid drop model (ELDM) using the combination of varying mass asymmetry shape description for the mass transfer (VMAS) and Werner-Wheeler's inertia coefficient (WW). The calculated half lives of ground-state to ground-state transitions for proton emission, alpha decay, cluster radioactivity, and cold fission processes are compared with experimental data. These comparisons show that the ELDM is a very efficient model to describe these different decay processes in a same, unified, theoretical framework. A table listing the predicted half-life values, τ c , is presented for all possible cases of spontaneous nuclear breakup such that −7.30 log 10 τ c [s] 27.50 and log 10 (τ/τ c) > −17.0, where τ is the total half life of the parent nucleus.