Speaker
Description
The rapid neutron-capture process (r-process) in astrophysical environments is considered to be responsible for the synthesis of approximately half of the elements heavier than iron. Precise experimental mass data for neutron-rich nuclei along the r-process path are essential for elucidating reaction pathways and resulting elemental abundances. We plan precision mass measurements of neutron-rich lanthanoid nuclei produced via the ${}^{136}\text{Xe}+{}^{176}\text{Yb}$ multinucleon transfer (MNT) reaction at the KEK Isotope Separation System (KISS) using a multi-reflection time-of-flight mass spectrograph (MRTOF-MS).
Maximizing production yields in MNT reactions requires the use of thick targets ($\sim 10\,\text{mg/cm}^{2}$). However, the relatively low melting point of metallic ytterbium ($\sim820\,^\circ \text{C}$) makes it susceptible to thermal damage under high-intensity beam irradiation. Consequently, the development of thermally durable targets is essential.
In this study, we developed thick targets using ytterbium oxide ($\text{Yb}_{2}\text{O}_{3}$), which has a high melting point of approximately $2400\, ^\circ \text{C}$. The $\text{Yb}_{2}\text{O}_{3}$ targets were fabricated using a spray deposition method. While this method enabled the deposition of layers with the desired thickness, the resulting films were found to be mechanically fragile, exhibiting easy peeling and crack formation. In this presentation, we report on the fabrication and evaluation of these targets, as well as the current status of ongoing efforts to improve their mechanical durability.