Description
The vicinity of ¹⁰⁰Sn is a rich landscape for studying nuclear isomers and exotic decay modes, including super-allowed α, βp, β2p, βα, and βpα emissions. This region is further characterized by enhanced neutron-proton pairing arising from its proximity to shell closure, making it an ideal testing ground for the nuclear shell model. In nuclear astrophysics, the rapid proton capture process (rp-process) follows a path close to the proton-drip line passing through the neighbourhood of 100Sn. Despite considerable interest and significant recent experimental progress [1-4], data on ground and isomeric states of nuclei near the proton-drip line remains missing or partially known. For example, in the silver isotopic chain, the mass of 95Ag was recently measured at the IGISOL facility but the predicted two long-lived isomers were somehow not observed [3]. Additionally, nuclei such as ⁹⁴Ag, ⁹⁶Cd, and ⁹⁸In exhibit N=Z spin-gap isomers, with ⁹⁴Ag standing out due to its multiple decay channels and two long-lived isomeric states—one of which features a uniquely high spin (21+) for a β-decaying isomer. Precise mass measurements of these isotopes are therefore essential to clarify and constrain theoretical predictions of nuclear structure in this region.
Penning trap spectroscopy, combined with the Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique, offers unparalleled resolving power and sensitivity allowing to distinguish states with very low energy differences and measure mass with high precision [5]. In this Letter of Intent, we propose to take advantage of the strengths of the S3LEB and the forthcoming PIPERADE double Penning traps at the DESIR facility to perform high-precision mass measurements of neutron-deficient nuclei near the proton-drip line. In parallel, the production of these nuclei could be carried out using SPIRAL1 via fusion-evaporation reactions in an optimized Target Ion Source System (TISS) coupled to a FEBIAD ion source, within the framework of the TULIP project [6]. The use of the PI-ICR technique in combination with PIPERADE should enable the resolution of states with minimal energy differences and mass measurements at a precision level of up to δM/M ~ 10⁻¹⁰. Additionally, isomers in the vicinity of ¹⁰⁰Sn could be further investigated through post-trap decay spectroscopy. Together, these measurements will not only benchmark theoretical nuclear structure models but also provide critical constraints for rp-process network calculations, thereby advancing our understanding of nucleosynthesis and refining predictions for the N=Z=50 region and beyond.
[1] G. Häfner et al., Phys. Rev. C 100, 024302 (2019)
[2] M. Mougeot et al, Nat. Phys. 17,1099–1103 (2021)
[3] Z. Ge et al., Phys. Rev. Lett. 133, 132503 (2024)
[4] G. Kripkó-Koncz et al., Phys. Rev. Res. 7, L042022 (2025)
[5] S. Eliseev et al, Phys. Rev. Lett. 110, 082501 (2013)
[6] V. Bosquet et al., Nucl. Instrum. Methods Phys. Res. B 541, 106–108 (2023)