Speaker
Description
ACTAR TPC is part of a new generation of active-target detectors specifically designed to meet the requirements of nuclear-structure investigations with radioactive beams in inverse kinematics. Commissioned in 2018 [1], the system has since been used in several experiments [2,3]. This talk will present results from two recent experiments at the GANIL and TRIUMF facilities, aimed at studying several neutron- and proton-rich nuclei.
The first transfer-reaction experiment with ACTAR TPC used an SPIRAL1 beam of $^{20}$O to measure proton-removal (d,$^3$He) [2] and neutron-removal (d,t) reactions. Filled with a gas mixture of 90% CD$_2$ and 10% C$_4$H$_{10}$ at 951 mbar, the TPC was coupled to an array of silicon pad detectors, enabling measurements of the residual energies of the recoiling light particles. By characterising the excited states in the final $^{19}$N and $^{19}$O nuclei, a simultaneous investigation of both proton and neutron shell evolution across the oxygen isotopic chain was performed. The results strongly support an evolution of shell-model magic gaps driven by the tensor component of the nucleon-nucleon force [4].
A more recent experimental campaign was carried out successfully at TRIUMF in 2025. Using proton and deuteron targets, experiments with $^{11}$Li and $^{20}$Mg beams were performed to investigate properties of near-dripline nuclei. This talk will provide an overview of the campaign and present preliminary results for selected physics cases.
References
[1] B. Mauss et al., Nucl. Instrum. Methods Phys. Res. A: Accel. Spectrom. Detect. Assoc. Equip. 940, 498–504 (2019).
[2] J. Lois Fuentes, “Complete spectroscopy of 16C and 20O with solid and active targets using transfer reactions USC”, PhD thesis (Universidade de Santiago de Compostela, 2023).
[3] A. Ortega Moral et al., Phys. Rev. C 112, L061302 (2025).
[4] T. Otsuka et al., Rev. Mod. Phys. 92, 15002 (2020).