Experimental study of the transfer-induced fission fragment angular distribution in the ${}^6\mathrm{Li}+{}^{238}\mathrm{U}$ reaction

Transfer-induced fission fragment angular distribution measurements have been carried out in ${}^6\mathrm{Li}+{}^{238}\mathrm{U}$ reaction at beam energies of 36 and 40 MeV in coincidence with projectile-like fragments. The fission fragment anisotropies for $\alpha$- and deuteron-transfer-induced fission reactions are obtained with respect to the recoil direction. The anisotropy values for transfer-induced fissions are observed to be either similar or lower than the inclusive measurement. In order to quantitatively understand the present experimental data on transfer-induced fission, anisotropy values have been compared with the preequilibrium fission model considering ground-state spin of the projectile and/or target. It is found that the model predicts the inclusive and exclusive anisotropy data reasonably well.

Figure 1

Schematic of the experimental setup showing MWPC's and strip detector positions with respect to beam direction.

Figure 2

Fragment angular distributions for inclusive data at energies 36 and 40 MeV. Solid lines correspond to the polynomial fit.

Figure 3

The typical two-dimensional spectrum of $\mathrm{\Delta }E$ versus $E$ residue for one of the strips of projectile-like fragment detector.

Figure 4

Transfer-induced fragment angular distributions at energies 36 and 40 MeV for $\alpha$ and $d$ transfer with respect to the recoil direction of the fissioning system. Solid lines correspond to the polynomial fit.

Figure 5

The experimental fragment anisotropies with PEF model predictions as a function of $E_{\mathrm{c}}.\mathrm{m}.$ for inclusive and transfer channels.

Figure 6

$K_{\circ }^2$ derived from RFRM [15] for inclusive, $\alpha$ and $d$ transfer represented as stars, circles, and triangles, respectively.