Roles of tensor force and pairing correlation in two-proton radioactivity of halo nuclei*

Abstract

The tensor force and pairing correlation effects on the two-proton radioactivity of $^{18}$Mg and $^{20}$Si with a pronounced two-proton halo are explored in the framework of the spherical Skyrme-Hartree-Fock-Bogoliubov theory. It is shown that the halo sizes are enhanced with the growth of strength of the tensor force and pairing correlation. Furthermore, the growing halo sizes lead to the enhancement of the diproton emission. Then, it is found the tensor force has a small influence on the two-proton decay energies and the two-proton decay energies calculated with the strong surface pairing are smaller than those with the weak mixed pairing. Because the two-proton decay energies are relatively large, the predicted order of magnitude of half-lives within the effective liquid drop model is not sensitive to the decay energy variation caused by the tensor force and pairing correlation, whose value is about 10$^{-18}$ s.

An improved effective liquid drop model for cluster radioactivity

“…In order to evaluate the half-lives of different radioactivity, the Gamow penetrability factor is obtained by considering the pre-scission phase of the two intersecting spherical fragments in the effective one-dimensional potential barrier based on four kinds of combinations of the mass transfer descriptions and the inertia coefficients. Therefore, the experimental halflives of various radioactivity could be reproduced well [15,[44][45][46][47][48][49][50][51][52].…”

“…These predictions may be helpful for searching for new candidates for cluster radioactivity in future experiments. Finally, it is necessary to point out that the proton radioactivity is an important decay mode for the extremely protonrich nuclei [51,52,[62][63][64][65][66]. So it is interesting to extend our approach to study the proton radioactivity, which is underway.…”

“…In the framework of the ELDM, the decaying nucleus is considered as two spherical molecular shape fragments of different radii in contact [15,[44][45][46][47][48][49][50][51][52], which is shown in figure 1.…”

“…In the framework of the ELDM, the cluster radioactivity is assumed as a super-asymmetric fission process [15,[44][45][46]. Besides the cluster radioactivity, one-proton emission, twoproton radioactivity, α-decay and cold fission can be described in a unified framework of the ELDM [15,[44][45][46][47][48][49][50][51][52]. In order to evaluate the half-lives of different radioactivity, the Gamow penetrability factor is obtained by considering the pre-scission phase of the two intersecting spherical fragments in the effective one-dimensional potential barrier based on four kinds of combinations of the mass transfer descriptions and the inertia coefficients.…”

“…However, for each combination of any type of radioactivity, only two constants (the nuclear charge radius parameter r 0 and the assaulting frequency ν 0 ) are adjusted to obtain the agreement with the experimental half-lives [15,[44][45][46][47][48][49][50][51][52]. As a result, the predictive power of the ELDM is not so strong, owing to the following two reasons: (i) Since the half-life of the charged-particle radioactivity is sensitive to the nuclear charge radius [53][54][55][56][57] a minor change will result in a large deviation of the decay half-life.…”