Fissionlike events in the ${}^{14}\mathrm{N}+{}^{181}\mathrm{Ta}$ system

Absolute cross sections for 22 fissionlike fragments concerning their decay mode via independent and cumulative cross sections have been measured at four projectile energies, i.e., $82.2\pm 0.8,79.18\pm 0.82,76.8\pm 1.2$, and $72.9\pm 0.91\mathrm{MeV}$. The recoil-catcher activation technique followed by offline $\gamma$-ray spectrometry was employed. The isotopic yield distribution and the variance for indium isotopes have been obtained from the experimental data and were found to be in agreement with the literature values. The fissionlike fragments mass distribution is found to be a single-peaked Gaussian distribution and confirms their population via deexcitation of the compound nucleus. The mass distribution variance is found to be narrower and exponentially increases as compared to relatively heavier systems at above 20% of the Coulomb barrier. A self-consistent approach for determining the isobaric charge dispersion parameters has been adopted. The present paper suggests that fission is one of the competing modes at low energies other than complete fusion and incomplete fusion processes.

Figure 1

Sketch of a typical experimental setup used for the irradiation.

Figure 2

Typical $\gamma$-ray spectrum of ${}^{14}\mathrm{N}+{}^{181}\mathrm{Ta}$ interactions at $E_{\mathrm{lab}}=82.20\pm 0.80\mathrm{MeV}$, where $\gamma$ lines are assigned to the different reaction products expected to be populated via the CF, ICF, complete fusion-fission, and/or incomplete fusion-fission processes.

Figure 3

A typical decay curve of gallium residue at obtained by following 115.01 keV $\gamma$-line.

Figure 4

Ratio of measured and pace calculated cross sections of evaporation residues in the ${}^{14}\mathrm{N}+{}^{181}\mathrm{Ta}$ reaction at $E_{\mathrm{lab}}=82.20\pm 0.80\mathrm{MeV}$. The dashed lines are drawn at unity.

Figure 5

Isotopic yield distribution for (${}^{106,108,109,110}\mathrm{In}$) indium isotopes in the ${}^{14}\mathrm{N}+{}^{181}\mathrm{Ta}$ reaction.

Figure 6

Fractional isotopic yield corresponding to corrected charge distribution.

Figure 7

Mass distribution of fission products in the ${}^{14}\mathrm{N}+{}^{181}\mathrm{Ta}$ reaction at the studied energies. Upward arrows indicate values expected to go up. The lines are drawn through the data points for the Gaussian fit.

Figure 8

Mass variance as a function of excitation energy for ${}^{195}\mathrm{Hg}$. The solid lines show the increase in ${\sigma }^2$ with $E^{*}$. The vertical arrow indicates the excitation energy corresponding to the Coulomb barrier.

Figure 9

Mass asymmetry vs variances for the three projectile-target combinations (Gubbi et al. 1996 [43], Dubey et al. 2016 [50], Rusanov et al. 2008 [51]).

Figure 10

Schematic of fission fragments and compound nucleus evaporation residues at $E_{\mathrm{lab}}=82.20\pm 0.80\mathrm{MeV}$. The solid lines are drawn through the data points to guide the eyes.