Fabrication of thin targets for nuclear reaction studies at IUAC

Abstract

Thin, durable, uniform, isotopic targets of 193Ir, 187Re, 182W, 181Ta, 175Lu and 169Tm of thicknesses ∼80 μg/cm2, 60 μg/cm2, 70 μg/cm2, 175 μg/cm2, 110 μg/cm2 and 270 μg/cm2, respectively, have been fabricated on carbon backing by physical vapor deposition technique for nuclear reaction studies at Inter University Accelerator Centre (IUAC), New Delhi. Preparation of very thin self-supporting targets of these elements is non-reproducible. A carbon backing thickness of ∼22 μg/cm2 was achieved. For the targets of refractory metals (193Ir, 187Re, 182W, 181Ta) e-gun evaporation was used. The lanthanide targets (175Lu, 169Tm) were fabricated using: (a) e-gun (for natC backing), (b) resistive heating (for source material deposition) and (c) e-gun evaporation (for natC capping) methods successively, without breaking the vacuum. Fabrication details of these targets, with actions taken against the challenges (peeling off, heat damage etc.) experienced during fabrication, are reported. No high Z contamination is found in any of the targets by RBS and XRF analysis.