Charge, mass, and angular distributions in ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$

Charge and mass distributions at $E_{lab}=114.4$ and $102.1\text{MeV}$, and the mass-resolved angular distribution at $E_{lab}=102.1\text{MeV}$ in ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$ have been studied using the recoil catcher technique followed by off-line $\gamma$ ray spectrometry. The mass distributions have been found to be symmetric at both energies. The data on the variance of the mass distributions from this work and from literature have been analyzed to investigate the effect of the fissility on the stiffness of mass-asymmetric deformations. The stiffness was found to increase up to $Z^2∕A\sim 34$ and decrease at higher values of $Z^2∕A$. Angular anisotropies of 16 fission products have been measured. The results show that the angular anisotropy is not significantly correlated with the mass asymmetry. The experimentally determined angular anisotropy, averaged over the mass, was found to be significantly higher than that calculated using a statistical saddle point model.

Figure 1

Plot of formation cross sections of fission products in ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$ at $E_{lab}=114.4\text{MeV}$.

Figure 2

Plot of isotopic yield distribution for Sb and I. Solid lines are Gaussian fit to the data.

Figure 3

Primary isotopic yield distribution curves (solid lines) for Sb (a) and I (b). Symbols represent the product yields as calculated from primary isotopic yield distribution. Dashed lines represent the Gaussian fit to the experimentally determined product yields.

Figure 4

Plot of fractional independent yields (FIY) of Sb and I isotopes as a function of their $A∕Z$. Solid line is Gaussian fit to the data.

Figure 5

Plot of fractional independent yields (FIY) of Sb and I isotopes, as a function of $Z-Z_p$. Solid line is Gaussian fit to the data.

Figure 6

Fission product mass distribution for ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$ at $E_{lab}=114.4\text{MeV}$ (a) without charge polarization correction to $Z_{UCD}$ (b) with charge polarization correction to $Z_{UCD}$.

Figure 7

Fission product mass distribution in ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$ at $E_{lab}=102.1\text{MeV}$.

Figure 8

(a) Plot of relative variance ${\left({\sigma }_M∕A\right)}^2$ vs $Z^2∕A$ and (b) plot of relative variance ${\left({\sigma }_M∕A\right)}^2$ vs ${\left(Z^2∕A\right)}_{eff}$.

Figure 9

Plot of $W\left(\theta \right)$ vs ${\cos }^2\theta$ for fission products in ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$ at $E_{lab}=102.1\text{MeV}$. Solid lines are least square fit to the data.

Figure 10

Plot of angular anisotropy of fission products as a function of mass asymmetry in ${}^{20}\mathrm{Ne}$ induced fission of ${}^{208}\mathrm{Pb}$ at $E_{lab}=102.1\text{MeV}$.