The BEtA Recoil-ion trap (BEARtrap): An ion trap dedicated to $\beta$-delayed neutron studies using recoil-ion time-of-flight spectroscopy*

Information on the decay properties of isotopes that undergo $\beta$-delayed neutron ($\beta$n) emission, such as the probability of neutron emission and the energy spectrum of the emitted neutron, is needed to gain a better understanding of the production of heavy elements in the cosmos, energy generation in nuclear reactors, and the fission-product signatures used for stockpile stewardship. The BEtA Recoil-ion trap (BEARtrap) at Argonne National Laboratory will be the first apparatus dedicated to studying $\beta$n emission through recoil-ion time-of-flight spectroscopy. This technique involves surrounding a cloud of ions held in a Paul trap with array of microchannel plate detectors, plastic scintillator telescopes, and high purity germanium detectors. This allows information on the neutron in the decay to be inferred by detection of the recoiling daughter and beta particle where both the probability of $\beta$n and the neutron energy spectrum can be obtained. The design of the trap structure and detector system, a summary on detector performance, and a discussion on commissioning plans will be presented.