Properties of fission fragments for $Z=112-116$ superheavy nuclei

The dynamical cluster decay model (DCM) is applied to understand the dynamics of ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U},{}^{244}\mathrm{Pu},{}^{248}\mathrm{Cm}$ reactions at comparable excitation energies across the barrier. To understand the capture stage of ${}^{286}112^{*},{}^{292}114^{*}$, and ${}^{296}116^{*}$ nuclei, the compound nucleus formation probability is calculated. The indication of $P_{CN}<1$ in the DCM framework demonstrates the fact that some competing process such as quasifission may occur at the capture stage of the ${}^{48}\mathrm{Ca}$ induced reactions. To understand this further, the comparative decay analysis of ${}^{286}112^{*},{}^{292}114^{*}$ and ${}^{296}116^{*}$, nuclei is carried out using ${\beta }_{2i}$ deformations within hot optimum orientation criteria, and the calculated fission cross sections find nice agreement with available data. The fission mass distribution shows a double humped structure where a symmetric peak observed around the Sn region appears to find its genesis in a symmetric quasifission component. On the other hand, the emergence of peaks around Pb in the decay of $Z=112$, 114, and 116 nuclei signify the possible presence of asymmetric quasifission. Higher and broader asymmetric quasifission peaks are observed for ${}^{296}116^{*}$ and ${}^{292}114^{*}$ nuclei as compared to ${}^{286}112^{*}$ nucleus. Beside this, the total kinetic energy (TKE) distribution of the decay fragments is also explored by using different proximity potentials, such as Prox-77, Prox-88, and Prox-00. Prox-88 seems to perform better and the calculated TKE values find relatively better comparison at lower angular momentum states. The possible role of different radii of the decaying nuclei is also exercised to understand the $\overline{\mathrm{TKE}}$ dynamics of ${}^{48}\mathrm{Ca}+{}^{238}\mathrm{U},{}^{244}\mathrm{Pu},{}^{248}\mathrm{Cm}$ reactions.

Figure 1

Scattering potential $V$ (MeV) for the entrance channel of ${}^{286}112^{*},{}^{292}114^{*}$, and ${}^{296}116^{*}$ nuclei at $\ell ={\ell }_{\max }$ with an excitation energy of $\sim 39$ MeV.

Figure 2

Fragmentation potentials minimized in mass coordinate $\eta \left(A\right)$ for the decay of ${}^{286}112^{*},{}^{292}114^{*}$, and ${}^{296}116^{*}$ nuclei, plotted at an excitation energy $\sim 39$ MeV and for the highest value of angular momentum $\ell ={\ell }_{\max }$ using the deformed choice of fragmentation.

Figure 3

Variation of preformation probability with the fragment mass for the decay of (a) ${}^{286}112^{*}$, (b) ${}^{292}114^{*}$, and (c) ${}^{296}116^{*}$ superheavy nuclei, by including the ${\beta }_{2i}$-deformation effects within the hot optimum approach, plotted at fixed neck-length parameter and highest value of angular momentum.

Figure 4

Variation of fragmentation potential with the angular momentum for most symmetric fission fragment and Pb-isotopes of asymmetric quasi-fission in the decay of (a) ${}^{286}112^{*}$, (b) ${}^{292}114^{*}$ and (c) ${}^{296}116^{*}$ nuclei.

Figure 5

Variation of penetration probability with the fragment mass for the decay of Z=112, 114 and 116 superheavy nuclei, by including the ${\beta }_{2i}$-deformation effects within the hot optimum approach. Symmetric fission fragments can have fusion-fission and quasi-fission origin. The penetrability of asymmetric quasi-fission fragments are also shown.

Figure 6

Preformation probability plotted with the fragment mass for the decay of (a) ${}^{286}112^{*}$, (b) ${}^{292}114^{*}$, and (c) ${}^{296}116^{*}$ superheavy nuclei with the application of different versions of proximity potentials, namely Prox-77, Prox-88, and Prox-00.

Figure 7

$\overline{\mathrm{TKE}}$ distribution of fragments plotted for the decay of (a) ${}^{286}112^{*}$, (b) ${}^{292}114^{*}$, and (c) ${}^{296}116^{*}$ superheavy nuclei, using hot optimum orientations and ${\beta }_{2i}$ deformations. The calculated $\overline{\mathrm{TKE}}$ values are plotted for Prox-77, scaled Prox-77, and Prox-88 values.

Figure 8

Scattering potential, plotted to observe the TKE (or $\overline{\mathrm{TKE}}$) values with the use of Prox-77, Prox-00, and Prox-88 potentials at fixed neck-length parameter $\left(\mathrm{\Delta }R\right)$ and maximum value of the angular momentum $\left({\ell }_{\max }\right)$.

Figure 9

Variation of $\overline{\mathrm{TKE}}$ with fragment mass for the decay of ${}^{286}112^{*}$, plotted at extreme values of angular momentum, i.e., ${\ell }_{\max }$ and ${\ell }_{\min }$ values, for the Prox-88 potential.

Figure 10

$V\left(R_a\right)$ or TKE values given for different radii used in the Prox-88 potential at $\mathrm{\Delta }R=0$, plotted at different values of angular momentum for the decay of ${}^{286}112^{*}$.

Figure 11

$\overline{\mathrm{TKE}}$ distribution of the fragments, plotted using the Prox-88 potential at $\mathrm{\Delta }R=0.0$ fm and at minimum value of angular momentum, ${\ell }_{\min }$, for ${}^{286}112^{*}$.