Surrogate neutron-capture studies with fission detection in inverse kinematics at the ESR storage ring

arXiv:2602.21256v1 Announce Type: new
Abstract: The NECTAR (Nuclear rEaCTions At storage Rings) experiment at the ESR heavy-ion storage ring at GSI Darmstadt is dedicated to surrogate reaction studies of neutron-induced reactions on heavy nuclei in inverse kinematics. In this work, we report on the implementation and performance of a newly developed fission-fragment detection system integrated into the NECTAR experimental setup. The upgraded detector configuration enables, for the first time in a surrogate experiment, the simultaneous detection of (gamma)-decay residues, multi-neutron-emission residues, and fission fragments. The full setup was used for the first time in an experiment where a stored beam of bare (^{238})U(^{92+}) ions at 17.24~MeV/u interacted with a gaseous deuterium target, populating excited (^{238})U and (^{239})U nuclei via the (^{238})U(d,d’) and (^{238})U(d,p) reactions. We describe the fission detector geometry, design constraints, and simulation-based efficiency determination. The target-like particle identification and beam-like residue spectra demonstrating the performance of the complete setup are also shown.