Decay analysis of pre-actinide and trans-actinide nuclei formed using various projectiles on a ${}^{197}\text{Au}$ target at $E_{\mathrm{CN}}^{*}=60$ MeV

The collective clusterization approach of the dynamical cluster decay model (DCM) has been applied to study the decay of odd mass nuclei ${}^{215}\text{Fr}^{*},{}^{223}\text{Pa}^{*},{}^{227}\text{Np}^{*}$, and ${}^{233}\text{Am}^{*}$, which are formed in heavy-ion-induced reactions. The aim of this study is to investigate the decay pattern and related behavior of these heavy mass nuclei formed in four distinct reactions involving different projectiles (with mass $A=18\text{–}36$) induced on ${}^{197}\text{Au}$ target nucleus. Further, in order to analyze the role of deformations, the calculations have been done by considering spherical choice of fragmentation as well as with inclusion of quadrupole $\left({\beta }_2\right)$ deformation. For the heavy mass region, with fission being the dominant decay mode, an attempt has been made to investigate the effect of projectile mass in reference to fission decay patterns of the pre-actinide ${}^{215}\text{Fr}^{*}$ nucleus and the trans-actinide nuclei ${}^{223}\text{Pa}^{*},{}^{227}\text{Np}^{*}$, and ${}^{233}\text{Am}^{*}$ formed at common excitation energy, $E_{CN}^{*}=60\mathrm{MeV}$. Besides this, the shell closure effects and the role of orientation have been explored, which suggest the presence of a noncompound nucleus process such as quasifission (QF) for the odd mass nuclei under consideration. For both the compound nucleus and the noncompound nucleus processes, the results obtained using DCM are found to have nice agreement with experimental observations. The isotopic and isobaric analysis is also worked out so as to have a comprehensive idea about the dynamics involved.

Figure 1

The variation of fragmentation potential $V$ (MeV) as a function of fragment mass $A_2$ for the decay of ${}^{215}\text{Fr}^{*},{}^{223}\text{Pa}^{*},{}^{227}\text{Np}^{*}$, and ${}^{233}\text{Am}^{*}$ nuclei, at $\ell ={\ell }_{\max }$ for (a) spherical and (b) ${\beta }_2$-deformed approaches at $E_{CN}^{*}=60\mathrm{MeV}$.

Figure 2

Preformation probability $\left(P_0\right)$ plotted as a function of fragment mass $\left(A_2\right)$ for the decay of ${}^{215}\text{Fr}^{*},{}^{223}\text{Pa}^{*},{}^{227}\text{Np}^{*}$, and ${}^{233}\text{Am}^{*}$ nuclei for (a) spherical and (b) ${\beta }_2$-deformed choice within optimum orientation $\left({\theta }_i^{\mathrm{opt}}\right)$ approach for hot (equatorial) compact configuration at $E_{CN}^{*}=60\mathrm{MeV}$.

Figure 3

Variation of barrier-lowering parameter as a function of (a) fragment mass, $A_2$, and (b) angular momentum, $\ell \left(\hslash \right)$, plotted for the decay of given compound nuclei for ${\beta }_2$-deformed choice of fragmentation at $\ell ={\ell }_{\max }$.

Figure 4

Preformation probability $P_0$ plotted as a function of fragment mass $A_i \left(i=1,2\right)$ for different compound systems (a) ${}^{215}\text{Fr}^{*}$, (b) ${}^{223}\text{Pa}^{*}$, (c) ${}^{227}\text{Np}^{*}$, and (d) ${}^{233}\text{Am}^{*}$ for the ${\beta }_2$-deformed approach, showing the presence of shell effects.

Figure 5

The variation of preformation probability $\left(P_0\right)$ as a function of fragment mass $\left(A_i\right)$ for the decay of (a) ${}^{215}\text{Fr}^{*}$, (b) ${}^{223}\text{Pa}^{*}$, (c) ${}^{227}\text{Np}^{*}$, and (d) ${}^{233}\text{Am}^{*}$ nuclei formed in $X+{}^{197}\text{Au}$ reactions plotted at $\ell ={\ell }_{\max }$ for the use of cold polar orientation.

Figure 6

Comparison of DCM calculated cross section with prediction of Zagrebaev and the measured experimental data [19].

Figure 7

Individual contribution of quasifission cross section $\left({\sigma }_{QF}^{DCM}\right)$ plotted as a function of angular momentum ($\hslash$) for ${\beta }_2$-deformed choice of fragmentation.

Figure 8

Comparison of fragmentation potential and preformation probability of ${}^{227,223}\text{Pa}^{*}$ isotopes plotted in panels (a) and (c) and isobaric nuclei ${}^{227}\text{Pa}^{*}$ and ${}^{227}\text{Np}^{*}$ plotted in panels (b) and (d).