Abstract
Nuclear mass is a fundamental property of atomic nuclei, reflecting the underlying nucleon-nucleon interactions and playing a key role in understanding the astrophysical r-process. We report on the construction of an RF gas cell coupled to a multi-reflection time-of-flight (MRTOF) mass spectrometry for high-precision mass measurements of nuclei in the vicinity of N =126. The gas cell serves as the crucial interface between reaction products and precision low-energy mass spectrometry, where the ions are stopped and thermalized in helium gas according to the Bethe-Bloch energy-loss mechanism. To suppress ion neutralization and improve the extraction efficiency, cryogenic operation and ion-surfing extraction with audio frequency (AF) signals are adopted. This integrated gas cell and MRTOF system provides an effective solution to the long-standing challenge of coupling reaction products to high-precision mass spectrometry. After commissioning, multi-nucleon-transfer reactions with projectile-target combinations of 238U +197Pt/184W/208Pb will be employed to populate neutron-rich nuclei around N =126. The precise mass data obtained in this region will provide neutron separation energies and constraints on neutron-capture properties, thereby contributing to a better understanding of heavy-element production in the astrophysical r-process.
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