Incomplete fusion in ${}^{16}\mathrm{O}+{}^{89}\mathrm{Y}$ reactions at energies of $\approx 7$ MeV/nucleon

Measurement of forward recoil range distribution (FRRD) of evaporation residues (ERs) populated in the ${}^{16}\mathrm{O}+{}^{89}\mathrm{Y}$ reaction at $E_{\mathrm{lab}}\approx 105$ MeV have been carried out by employing the offline characteristic $\gamma$-ray detection method. The FRRD pattern of ERs populated through $xn$/$pxn$ channels comprises a single peak only whereas ERs populated through $\alpha$ emitting channel have multiple peaks in their FRRD. FRRDs of the observed ERs support the presence of the complete fusion (CF) process in the population of $xn$/$pxn$ channels residues and an admixture of complete and incomplete fusion (ICF) processes in the population of $\alpha$ emitting channel residues. The observed ICF process in the population of $\alpha$ emitting channel residues is explained through the breakup fusion model. The fusion function is derived from the experimental CF cross section data and the extracted fusion function is compared with the universal fusion function to estimate the degree of ICF contribution to the total fusion cross section. An attempt has also been made to explore the dependence of ICF probability on target charge.

Figure 1

A schematic diagram of target-catcher foil arrangement used for the study of the forward recoil range distribution of ERs populated in the ${}^{16}\mathrm{O}+{}^{89}\mathrm{Y}$ reaction at $E_{\mathrm{lab}}\approx 105$ MeV.

Figure 2

Typical $\gamma$-ray energy spectrum of the residues populated in the ${}^{16}\mathrm{O}+{}^{89}\mathrm{Y}$ reaction at $E_{\mathrm{lab}}\approx 105$ MeV recorded for 100 seconds, 15 minutes after the termination of the irradiation.

Figure 3

Half-life decay curve of (a) ${}^{94g}\mathrm{Tc}$ (4.88 h) and (b) ${}^{101}\mathrm{Ag}$ (11.1 min) residues populated in the ${}^{16}\mathrm{O}+{}^{89}\mathrm{Y}$ reaction at $E_{\mathrm{lab}}\approx 105$ MeV.

Figure 4

Experimentally measured FRRD of ERs (a) ${}^{101}\mathrm{Ag}$, (b) ${}^{101}\mathrm{Pd}$, (c) ${}^{99}\mathrm{Pd}$, and (d) ${}^{100g}\mathrm{Rh}$ populated through $4n$, $p3n$, $p5n$, and $\alpha n$ channels, respectively. The solid lines through the data points are the Gaussian fits of the experimental data points (solid circles).

Figure 5

Experimentally measured FRRD of ERs (a) ${}^{99m}\mathrm{Rh}$, (b) ${}^{98}\mathrm{Rh}$, (c) ${}^{95g}\mathrm{Tc}$, and (d) ${}^{94g}\mathrm{Tc}$ populated through $\alpha 2n$, $\alpha 3n$, $2\alpha 2n$, and $2\alpha 3n$ channels, respectively. The relative contributions arising from CF, ${\mathrm{ICF}}^{\alpha }$, and ${\mathrm{ICF}}^{2\alpha }$ processes are also mentioned in the figures. The solid lines through the data points are the Gaussian fits of the experimental data points (solid circles).

Figure 6

Sharp cutoff approximation as well as predicted angular momentum distribution using the code ccfull for the ${}^{16}\mathrm{O}+{}^{89}\mathrm{Y}$ system at $E_{\mathrm{lab}}\approx 105$ MeV. See text for details.

Figure 7

The CF fusion function $F\left(x\right)$ as a function of $x$ for the $\alpha$ cluster projectile ${}^{16}\mathrm{O}$ on different targets. The solid line represents the UFF and the dotted line is the UFF multiplied by a suppression factor of 0.85.

Figure 8

Average fusion suppression as a function of $Z_T$ for the ${}^{16}\mathrm{O}$ induced reaction on different targets. The solid line is an empirical prediction given by Hinde et al. [43]. See text for details.