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The fusion of heavier mass nuclei is a complex process significantly influenced by the entrance channel of the colliding nuclei. Notably, the mass asymmetry of the colliding nuclei can impact the fusion process, with symmetric systems often exhibiting inhibited fusion compared to asymmetric ones, particularly in the mass region around 200 [1,2]. Evaporation residues (ERs) are considered a definitive indicator of fusion, as their formation necessitates the nuclei to traverse the compound nucleus (CN) phase. This makes them a sensitive probe to study the entrance channel effect in the presaddle region. In this work, we aimed to understand these underlying effects through the measurements of ER cross-sections and ER-gated spin distributions [3,4] for two different reactions: $^{48}$Ti + $^{160}$Gd and $^{30}$Si +$^{178}$Hf. Both reactions form the same compound nucleus, $^{208}$Rn. These measurements were conducted using the HYbrid Recoil Mass Analyzer (HYRA) coupled with the TIFR 4$\pi$ spin spectrometer at the Inter University Accelerator Centre (IUAC), New Delhi [5]. Beams of $^{48}$Ti and $^{30}$Si were pulsed to provide the width of $\sim$1 ns with the separation of 250 ns and 2 $\mu$s respectively. Isotopically enriched thin targets of $^{160}$Gd ($\sim$220 $\mu$g/cm$^2$ ) and $^{178}$Hf ($\sim$130 $\mu$g/cm$^2$ ) were bombarded with ion beams at nine different energies. The energies ranged from around the Coulomb barrier to 20$\%$ above the barrier. The magnetic field and gas pressure of the HYRA were optimized to maximize the transmission of ERs to the focal plane. The ERs were detected using the position sensitive multiwire proportional counter (MWPC) positioned at the focal plane of HYRA. The closely packed array of 29 NaI detectors was mounted around the target chamber to capture the gamma rays emitted. The total solid angle covered by the 4$\pi$ multiplicity array is $\sim$86$\%$ [6]. $\\$
ER yields were extracted from the two dimensional coincidence spectrum between energy loss ($\Delta E$) and time of flight (TOF) of ER . From an experimentally measured $\gamma$ fold, ER-gated $\gamma$ multiplicity distribution was extracted. Our initial analysis indicates a significantly lower ER cross-section for the more symmetric system, $^{48}$Ti + $^{160}$Gd , compared to the $^{30}$Si + $^{178}$Hf. This clearly demonstrates that the outcome of the fusion process is influenced by the specific choice of the entrance channel. Further analysis of the spin distribution measurements is currently underway.
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