Fabrication of self-supporting targets of lead (206,208Pb) using evaporation technique

The self-supporting 206,208Pb enriched isotopic targets of thicknesses varying from 500 μg/cm2 to 800 μg/cm2 have been prepared in the high vacuum environment at the target laboratory of Inter University Accelerator Centre (IUAC), by using the resistive heating method. The limited amount of the target material, selection of the parting agent, highly oxidizing tendency of the Pb in the atmosphere and the separation of the lead film from the glass slides were the few major challenges faced in the fabrication of the targets. A limited amount of isotopic material (100 mg) was utilized for the preparation of more than 20 thick self-supporting targets of 206Pb and 208Pb isotopes. Several attempts were made to overcome the difficulty of finding a suitable parting agent to avoid direct contact of water with the target material are discussed, along with the methods adopted for the fabrication of the targets. Further Energy Dispersive X-ray (EDX) analysis was performed to check the elemental purity of the foils. These targets have been successfully used for several nuclear physics experiments using the neutron detector setup known as National Array of Neutron Detectors (NAND) at IUAC, New Delhi.