Fabrication of thin Al-foils using vacuum evaporation technique

Earlier existing studies reveal that Excitation Function (EF) and Forward Recoil Range Distribution (FRRD) Measurements is the sensitive probe to extract the information regarding various entrance channel parameter effects on incomplete fusion reaction dynamics at intermediate energies. As, it is well established that ICF process starts competing with CF process at energies just above the Coulomb barrier and its influence increases with increasing the projectile energies. In order to understand the reaction mechanism of complete (CF) and incomplete fusion dynamics, we have planned to measure the excitation functions (EFs) and recoil range distribution (RRDs) of evaporation residues using stacked foil activation technique. These experiments will be performed using OFF-Line measurement techniques in General Purpose Scattering Chamber (GPSC) at Inter University Accelerator (IUAC), New Delhi. The evaporation residues produced in the projectile-target interactions will be captured in the stopping medium. In present planned experiments, Al-foils will be used as stopping medium to trap the recoiling residues as energy degraders as well as catchers. Generally, aluminum is used as backing material for the preparation of non-self supporting targets, for light and heavy-ion induced reactions. The basic reason behind using the Al-catcher foils is that the background activities produced with aluminum is low. Hence, the yield of evaporation residues produced must be known precisely, especially in off-beam experiments, where the Al-foils are used as stopping medium to trap the evaporation residues with different targets. For EFs measurement, thick Al-foils are required to stop the evaporation residues completely, while in case of FRRD measurement, thin Al-catchers are required. Thick Al-foils used as degraders for EFs measurement are prepared by rolling machine technique of thickness ranging from 1.2-2.5 mg/cm². On the other hand, the fabrication of thin Al-catcher foils of high uniformity and required thickness around 50μg/cm² was not possible by using the rolling machine. For the preparation of thin Al-catcher foil, the vacuum evaporation technique was adopted. In the present work, the fabrication of thin Al-catcher foils was successfully carried out by using the vacuum evaporation is being reported