Design and Construction of a Resonating RF Circuit for the BEtA Recoil-ion Trap (BEARTrap) Experiment at Argonne National Laboratory

Beta-delayed neutron emission occurs in neutron rich isotopes when the precursor undergoes beta decay and the decay kinematics allow the daughter to subsequently emit a neutron. The properties of this neutron emission are important for developing future nuclear reactor technology, as well as understanding r-process nucleosynthesis. Aligning with these motivations, the BEtA Recoil-ion Trap (BEARTrap) is being constructed at Argonne National Laboratory. This experiment is designed to determine the properties of beta-delayed neutron emission of radioactive beams produced by CARIBU. Using a Paul Trap, the precursor nucleus can be confined to the center of the trap. Once the precursor decays, the time of flight of the recoiling daughter nucleus can be measured relative to the beta particle. This will allow for the identification of beta-delayed neutron emission events as well as determining the energy of the delayed neutron. In order to have an accurate time-of-flight measurement, the precursor will be confined to the center of an open-geometry Paul trap. The trap is segmented 5 times along the trap axis. This requires a circuit to apply the required combination of RF and DC voltages to the 20 electrodes comprising the trap. A circuit was designed to provide two phases, 180 degrees apart, of a radiofrequency voltage in the frequency range of 100-900 kHz and a maximum voltage of ~500 V to allow radial confinement. In addition, the circuit couples a DC offset to the five segments to provide confinement along the trap axis. Finally, the circuit will also be able to apply an independent AC pulse across the five segments to enable injection and ejection of ions. The construction and design specifics of this circuit will be discussed in this poster presentation.