Fabrication and characterization of highly enriched thin 176Yb targets for the reaction dynamic studies on fission mass distribution

Abstract

The fabrication, transfer, and storage of a highly enriched isotopic target is very much crucial because of air gases and moistures being chemically active at room temperature. One must limit the amount of time that the target surface is exposed to the atmosphere during the transfer of air sensitive targets. The highly interactive targets are not easy to store for longer time and demand an in-vacuum transfer facility. Getting an alternative technique to remove all such imperative is a need of the hour specially for the nuclear physics community, more particularly for reaction dynamic studies of fission fragment mass distribution induced by stable and radioactive ion beams. Highly enriched materials are rare and very expensive, so an effective and highly efficient technique is needed to deal with such materials. Here, an attempt has been made to fabricate 96.63% enriched thin targets of 176Yb by evaporation techniques enabling ≈129.1 μg/cm2 thickness with a ≈25.93 μg/cm2 carbon backing to increase its stability and durability. Numerous trials have been performed using natural Yb to optimize the evaporation setup and associated growth parameters for efficient Yb isotope deposition with thin film deposition unit and diffusion pump based coating unit at Inter University Accelerator Centre (IUAC), New Delhi. Thickness and elemental composition of the targets have been analysed using characterization techniques such as X-ray diffraction, α-energy loss technique, Rutherford backscattering spectroscopy and energy dispersive X-ray spectroscopy. Essentially no significant impurities are found by these measurements, describing high purity and robustness of the fabricated targets. During the nuclear experiments, 30Si and 16O beams of intensity of the order of ≈1010 particles per second were bombarded on the targets for 5–6 days and no ill effects on the target were observed. Isotopic abundance of the target has been obtained experimentally, which ensured the isotopic purity of the target required for the reaction studies. This article will admire our readers about the qualitative nature of the fabrication technique, measurement and characterization citing valuable insights, aiding in a comprehensive understanding of their quality.