Single-particle and collective motions from nuclear many-body correlation (PCM2025)

Investigating Shell Structure at N=32 and 34 in Neutron-Rich Nuclei Using High-Precision Mass Measurements

5 Mar 2025, 15:23

1m

Main Lecture Hall (University of Aizu)

Poster session

Speaker

Shun Iimura (Rikkyo University)

Description

In this study, we discuss the shell structure at $N=32$ and $34$, newly recognized magic numbers in neutron-rich nuclei, in the context of deformation toward $N=40$ based on nuclear mass implications. Mass measurements of isotopes ${}^{55}$Sc, ${}^{55-58}$Ti, and ${}^{55-59}$V were conducted during the first commissioning of the ZD-MRTOF system at the RIBF/RIKEN under the SLOWRI project. The newly installed experimental system, situated downstream of the ZeroDegree (ZD) spectrometer in the BigRIPS experimental area at RIBF/RIKEN, includes a radiofrequency carpet-type helium gas cell (RFGC) coupled with a multi-reflection time-of-flight mass spectrograph (MRTOF). In this initial low-energy experiment at BigRIPS, high-energy products were captured and decelerated in helium gas, then extracted through an aperture using an RF microstructure into a Paul trap ion guide. The cooled, thermalized ions were injected into the MRTOF system as a high-quality beam for high-precision mass measurements. We present the features of the ZD-MRTOF system and share experimental results. These new data allow us to examine the $N=32$ and $34$ sub-shell structures in comparison with predictions from the Monte Carlo shell model (MCSM). Furthermore, we expand our discussion by incorporating recent research trends related to the evolution of nuclear shell structure in neutron-rich isotopes.